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triviaggukcore · 5 years

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her blooming flower | one

prologue / one / two

→summary: you’ve known him since you were just a young girl during his trainee days. He watched you grow into a woman, but he’s always hated you from day one for whatever reason it may be. To you, he thought of you as a nobody. But what you weren’t aware of was a secret that he never wanted you to know.

→pairing: enemy!jungkook x dancer!reader

→word count: 7.6k

→genre: angst, fluff, maybe smut??, some humor

→warning: implied smut

→a/n: hi guys, it’s finally here! I’m so sorry it’s been almost two months! It’s been super hectic from having family over the break and having no time to write. And it became even more hectic as my schedule became packed when coming back to second semester of school. I had theatre rehearsals every day after school until 6pm to prepare for our musical back in January with so much homework and chores to do, and then I was gone with my dance team at Disney World for 4 days which also didn’t give me any time to write, and missing three school days. I had to make up a bunch of work to bring up failing grades which had me super stressed out. Now that it’s February, it’s competition season and this past Saturday was the second contest. I’ve just been constantly tired physically, mentally, and emotionally where I just lost so much motivation to write. But I definitely took time in between my spare time to try the best I could. So thankfully, it is now here and the good news, I have a two week break before last contest. I will say this series will have a bit of slow updates. It just all depends on how packed my schedule is. But most of all, I would like to thank you all for being super patient with me, I really appreciate it sweeties! I would also like to thank @9uk and @stxrrysuga for being wonderful helpers into keeping me motivated and writing just a few small details that’ll help me get going.

Another side note, I’d like to credit and thank @dearmyjimin for granting me permission to use a concept she made on her blog which I was desperate and in such need for this series since I felt like it could absolutely be perfect for the storyline. Once again thank you!! The concept is based on 3J! That is all I have to say as you all should read and find out what it is.

So here it is finally! Chapter one! Enjoy!

It was dawn when you had woken up, your eyes drowsy from the lack of sleep you had been getting the last few days. The constant late nights because of work had kept you up at ungodly hours of the night. You tried to get fewer hours but you knew you needed the money so you stuck with the long hours and your days dragged on, each one seemed longer than the next. You sat up and sighed softly as you climbed out of bed while grabbing your glasses and putting them on. Your mind clouded with thoughts of what was going to take place later today, so you walked over to your desk and took a glimpse of your planner that you created almost a year ago.

Today, at 8am, you have breakfast with your best friend Jess, a contemporary lesson at noon, then lunch at 1pm, and then game night at Taehyung’s, including a no work shift today.

Okay, not so much to do today. Thank God. You grabbed your phone and put some music on shuffle with your mini speaker, then made your way over to the bathroom. You did your daytime skincare routine after doing your business on the toilet. While washing your face, you wondered how could you get this far in life. No, you’re not famous. You thought it would be kind of a scary career. But you still wanted to dance and create amazing pieces for artists for the wish of sharing your work to the world. Plus, you have choreographed for some artists before.

You’re not always booked for appointments with idols, but your schedule does get tight due to the fact that you work. You basically have a job at this cafe in Seoul, and you’re still working at your mom’s studio, hosting classes every Monday, Tuesday, and Thursday night. You usually teach contemporary and ballet but you have taught some hip hop classes too, due to the fact that you’ve choreographed for some idols as an example. It’s been requested by many residents who take your classes for you to teach more hip hop. And you might as well take that chance to balance all the styles out.

Looking at your face in the mirror after washing your face, you also thought about how life was for you when you moved to Korea. You missed your friends from back home, but you also love it here too. And you made some decent close friends here too, especially Jess being the closest friend you see literally every day. And of course, you can’t forget the Bangtan boys. You grew close with the boys over the years, they basically became your family. You always had fun with them, whether it was game nights or through video chat. And you have a very special bond with each of the boys, nothing was ever different from how you all acted with each other.

They adore you a lot, and you were like their very own little sister that they look out for. They all found you sweet and sincere, prestigious, intelligent, and super adorable. Well, except Jungkook. He, being the only one who disagrees, finds you as the exact opposite. He’s got one hell of a grudge against you. All because of a damn smoothie you accidentally spilled on him a couple years ago. You find it super confusing and a little dumb that he treats you like shit over that incident. Although, it saddens you too as you took the blame upon yourself, coming up with the many excuses in your head. Maybe he was having a really bad day and you just so happened to ruin it even more. If you were paying a little more attention, you would have caught yourself and not spilled your smoothie on him. Then maybe, just maybe, you could have had a better introduction with each other and become friends.

Jungkook loves to criticize and pick on you. Everyday. That’s no surprise to you. But you don’t usually conduct to anything he does to you, and it made him full of annoyance from how you wouldn’t try defending yourself (more so, argue). But there’s a reason why you don’t. If you ever stood up against Jungkook, you’re sure that he will probably laugh his ass off at your pathetic self. You don’t think you could ever try to face him with defense. It doesn’t work that way for you. Sure, it hurts you. But you find it useless to do so. And being the sweet person you are, you’re not gonna want to come out as some bitch.

No matter how much you respect him and treat him nicely, your presence is what makes him irritated. The man has got a grudge against you.

Sliding out of your pajamas, you threw on a random outfit and then you sat down at your vanity set and decided how you were going to look upon your face and hair. After 30 minutes, you were already putting on a pair of shoes at your front door. You grabbed your bag and car keys, and you were out the door of your apartment. Shortly then, you were on the road.

“Okay, so here are all my ideas for the boys’ next comeback. I’ve been working on this for a couple of days now and I thought I’d share them with you!” Your friend Jess said, dropping a plain journal in front of you next to your plate full of breakfast. You picked up the journal once you set your vanilla latte down and opened the journal, flipping through the ridiculous full pages of notes and ideas followed up for BTS’ comeback.

You gave her a glance, “You are crazy. Are you seriously helping them find new concept ideas? I thought they already figured that out.”

She shrugged, “Not exactly. Besides, they asked for my help so I could have better ideas on what music to produce with Yoongi and Namjoon.”

“A sexy comeback darker than the Love Yourself: Tear and Wings era?” You read aloud, “Sounds kinda…”

“Kinda good right? I think it’s time they now get into that, and besides, they’re all adults now that Jungkook became one.” She mentioned.

“You do know he’s been an adult for a few years now.”

Jess glared at you, “And him being an expert shirt lifter was only the beginning of his little bad boy era.”

The thought of Jungkook and his image only made you feel weird. He grew up drastically and puberty hit him harder than a truck. Instead, it was more like god and the devil worked together to mix cute and hot in their mixing bowl but decided to go with he’s gonna make every person gush in adoration and suddenly they get down on their knees and are thirsty hoes. But, there’s no denying that he really had you gawking at him. After all, you do like the man.

You nodded, “Wow, how logical.” Your sarcasm erupted as you took a sip of your latte. She hummed, “You know it’s true. Anyways, what’s going on for you today? Are you coming to game night?”

“Yeah, I am. I have a contemporary class to teach at noon, then lunch, and then I have a whole day to myself until game night. I think I might do some shopping, maybe go to the book store and read a few novels since my package arrived there. If I have time, I might just work on my poetries.” Yes, you write since you found your love for novels. Thanks to your dad’s career. He’s the best selling author in the country and back in yours.

“Speaking of dance,” Jess started, “Did you hear about 3J Studio?’

Yes, 3J as in J-Hope, Jimin, and Jungkook, the BTS dance line. They built a dance studio for those who want to have exclusive dance lessons with the boys. Millions of people have signed up for classes just so they can stand a chance to be coached by the boys. You were yet excited and definitely going to their first class on Saturday.

You nodded, “I did. Jimin and Hoseok told me about it. I’m really excited about this Saturday.” You smiled. “Me too!” Jess gushed, “Are you planning on attending?” She asked. “Of course! For sure I’m taking Jimin and Hoseok’s class.”

“Oh, but not Jungkook’s?” She raised an eyebrow. You sighed, “I mean, I’m not sure if I want to. I know he’s a great dancer and I’m certain he’s going to be an amazing coach but do you really think I want to feel the awkward tension where his blood literally boils around me? I’m not sure if I even want people to be speculating his hate for me. That’ll just put him at risk.” You fiddled with the thin straw in your latte, stirring it.

“But it’s not like he would ever talk to you in front of his students, would he? He’s an asshole, don’t get me wrong. Yet, I’m pretty sure he’s not an ass to treat you like crap.” Jess stated, “There’s no way he would do that to you in front of many people.”

“I guess you’re right.” You shrugged. The guy always puts you down and even humiliates you, he probably wouldn’t do that in public otherwise it would defame his image. The people wouldn’t even know who you are anyways. You’re only specified as, BTS’ friend, BTS’ music producer, Jess’ friend, Min Yoongi’s wife’s friend. It’s pretty much anything with you labeled as a friend of the band.

“He’s such a dumbass.” Jess shook her head. You looked up at her, “Hey, don’t say that about him. You know that’s not nice.”

She rolled her eyes and glared at you, “Really? Y/N, You’re defending him when all he ever does is bitch at you? He’s one hell of a brat who’s still stuck up on that smoothie mess! He makes me want to shove my foot in his face.”

“But you know he doesn’t have to like me right? Come on, Jess. Besides, the accident was my fault anyway.” You said softly as your eyes wandered somewhere else. “You really like him, don’t you?”

Your head snapped back at her, “Just because I like him doesn’t mean that has to do with what happened in the past.”

“Oh, so defending him and constantly worrying about his health along with your care and support in every accomplishment he achieves doesn’t mean anything to the way you feel about him?” Jess caught you there. “It’s not that I… I don’t know, Jessica.” You sighed, holding your cup firmly with both hands, “I respect him whether he doesn’t like me or not. My feelings don’t matter. He would never feel anything romantic for me. Besides, he has a girlfriend who’s definitely prettier and has a more slammin’ body than me.” You awkwardly locked a piece of your hair behind your ear.

“And this is where I call you stupid.” Jess looked at you, “That girl could never compare. She’s only got a pretty face but not a nice personality. Plus, you’re freaking gorgeous. More than she is. I don’t think you have any idea on that she’s only dating Jungkook for the attention and the fame.” She ate a bite of her egg sandwich, speaking in a mouthful, “The girl is a hooker but Jungkook being his gullible dumbass self believes she loves him for him.

You sighed, “Of course.” He loves her.

“And 5, 6, 7, TILT. Excellent!” You complimented, watching through the mirror as everyone in the studio did a tilt from the floor and rolled into fetus position. “So that whole 8-piece, just remember that it’s very very subtle, not too much energy until after the tilt, which you want to push your legs up and extend them like a whip but as light as a feather. Have grace with the tilt. 5, 6, 7, UP!” You demonstrated by being an example and showing your students the technique.

“She’s good isn’t she?” Jimin said with his arms crossed as he observed your teaching skills and your charismatic moves. “I’m really surprised she declined the trainee offers from the entertainment industries.” Hoseok nodded in agreement. A chuckled then came along, “I’m not.” Jungkook smirked.

“Dude, you’ve been going against every word we say about her.” Hoseok crossed his arms to face Jungkook. “Since day one.” He specifically added. Jungkook narrows his eyes as if he couldn’t comprehend what Hoseok was trying to get at.

But only the blind wouldn’t be able to tell that Jungkook bears a deep, stubborn grudge on you. And his attitude towards you contrasted too much from his members for them to not notice his behavior. It was an issue constantly swept under the carpet to not escalate things given Jungkook’s temper, but the matter has finally rose from dust. “Yeah that’s right, did she do something to offend you or something?” Jimin looks at Jungkook worriedly. The both of them kept going on about the issue of you, pressing Jungkook to the end of wits.

“Yo, if you have seen...another side of her she’s not showing to us,” The three of them slowly spin to watch you conduct the dance class. The smile on your face when you teach, and the way you go about asking every student about their struggles and issues—make Hoseok doubted the words that came out of his mouth. You looked genuinely passionate in this company, and it couldn’t be that you put up an act in front of evil intentions for so long. As long as however many years. Jungkook remains his gaze on you for a while, before his hands are coming up to rip off his hair from his scalp in frustration as he groans. “I-It’s not like that..! It’s just.. just the sight of her irks me!” He knew he sounded like a brat hating on someone as innocent as you for no reason at all. But before he could save himself from further embarrassment, you are strolling towards his triangle of friends with an anticipated look cast on your features.

“What are you guys talking about?” Your voice interrupts his rant. The three men stare at you in expressions you can’t make out—you couldn’t tell what they were thinking. Then the both Hoseok and Jimin shot Jungkook looks.

“Uh…” Jimin darts his gaze back and forth his two friends, before pulling you by the arm away from them. “Come on, let’s get a drink.”

And with that, you and Jimin walked out into the hallway to the studio kitchen where there were a few staff eating lunch. “So are you going to join us this Saturday at our studio?” You took out a bottle full of cold water from the refrigerator when you opened as Jimin leaned on the wall next to him. “Definitely. I’m excited what you guys have in store for your lessons and I’ll be taking them all too.” You took a couple sips from the water. Jimin looked at you with a raised eyebrow, recalling that you are taking ALL the lessons, “And by all, you mean you’re going to participate in Jungkook’s class too?”

You clenched your lips together in awkwardness, “It wouldn’t be fair if I didn’t take his but yours and Hoseok’s would it?” You sighed, “And besides, even if he cared, he’ll forget I’m even there. He’s going to have a class filled with people, and his main focus is his students.” Leaning against the counter backward, you always felt awkward talking about him with his members, and it wasn’t because you didn’t want to say the wrong thing at all. His hyungs were always lecturing him about you and never accepted the behavior he acted upon you. They didn’t know what really happened the day of the stupid incident because he never liked to talk about it or else he would have been made fun of or worse. They don’t even know why he’s held a grudge against you for so long. So what is the problem? When will he man up and get over it?

Jimin sighed, “At least you’re not an asshole like him.”

“Truth or dare?” Taehyung looked over at Jess as he popped the question.

“Dare.” She smirked.

After playing Jenga, Uno, checkers, and a whole bunch of other games in Taehyung’s house, everyone, including some of the boys’ girlfriends, are sitting in a circle on the floor with beers and snacks playing truth or dare. And unfortunately, Jungkook’s girl, Yuna couldn’t be there. But you felt relieved and happy about it. She’s just as worse as Jungkook. Pretty yet mean and nasty to you.

“Funny you guys are bickering but since you all ate my jjigae, I haven’t gotten a single bowl of it you hungry ass pigs!” Jin exclaimed just when Taehyung and Jess bickered over who has the best shoes.

“It was some good shit though.” Taehyung’s mouth waters, “I wish I could have more.”

Jin mumbles something under his breath and takes one huge gulp of his beer.

“Okay moving on. Truth or dare, Y/N?” Jimin turns to you. You kept your knees close to your chest, looking down as you weren’t prepared for your answer. You were always unsure and nervous about whatever choice you choose. You could feel everyone’s eyes on you, especially Jungkook with his little smirk.

“Ummm… truth?” You weren’t sure but went with it anyway. “Who was your first kiss?”

And that question almost made you shit yourself, “W-What?” You could feel your eyes widened.

How the hell were you going to tell that you’ve never kissed anyone before without feeling embarrassed?

“I’m sure she doesn’t want to reveal her privacy.” Namjoon noticed the nerves just by the position you were in. You were hugging your knees which were up to your chest. Jess even looked over at you in such worry since she’s the only one who knows you haven’t had the experience.

You gulped and stuttered, pushing up your glasses, “I uh… I actually never kissed anyone before.” You said softly as you looked down.

Taehyung raised his eyebrows in surprise, “What? No way. Seriously?” You looked up at Taehyung and looked at all the other reactions. They seemed just as surprised as him.

“That’s surprising.” Yoongi nodded in agreement. Jungkook rolled his eyes in annoyance, “Not a surprise to me, I mean look at her.” He looked over at you in disgust and you only looked down in shame. You felt so embarrassed and disgusted with your own self with not having any experience with a guy at all.

Jess glared over at him just as her blood was boiling, she could beat his ass at any second now, “Shut the fuck up, you ass. She doesn’t need your nasty opinions.”

Jungkook shrugged, “Like I care.”

“I think it’s great that she’s never kissed anyone, Jungkook.” Nari, Taehyung’s girlfriend, spoke in regards to defending you. Nari is sweet and soft, and even a creative person. She’s a cosmetologist in makeup and is definitely talented in making so many makeup combinations. She’s short and a few years older, around the same age as Taehyung. She has gorgeous glowing honey skin with long black colored curly hair, and lovely blue eyes. She’s just as beautiful as Taehyung and to you, they’re considered the most beautiful couple ever.

“It’s a good thing, stop being an ass Jungkook,” Jimin glared at him. You sat there awkwardly but you gave a little smile at Nari for giving her defense.

“Don’t mind him, Y/N. It’s good that you haven’t had your first kiss. You don’t need one, not even a guy. You’re a strong independent woman who doesn’t need a man.” Hoseok, who was sitting beside you, smiled at you with a good rub on your shoulder, “And you are also a beautiful woman.” He added, being sweet and full of sunshine as always. You could feel yourself blush and get shy at his compliment, “Thank you.” You nodded.

Of course, Jungkook shook his head unsatisfied. He knew that you never had a boyfriend. Everyone knew. And he was sure that you weren’t ever going to get one. But what he didn’t know was that you were definitely talking to someone as opposed to be dating soon.

“What do you mean she’s talking to Jonghoon?” He asked Taehyung as he looked at him in disbelief. It was the next morning and the two boys were in the kitchen making themselves some breakfast.

Taehyung glanced over at Jungkook from where he was cutting tofu, “What do you think I mean?”

While sighing, Jungkook bit his lip in question while he shook his head, “You’re kidding me right? He’s a frat! Does she not know that?” Was he actually for real? There’s no way you could be talking to some player. Jonghoon is a friend of Taehyung’s who used to be a trainee at BigHit. He’s damn beautiful and looks like he could be related to Taehyung. Tall, caramel skin, built, an unreal God like face, yet he’s definitely one hell of a man who only hooks up and has one night stands, leaving girls the very next day. Jungkook wasn’t very fond of him because he knows he isn’t the type of guy himself to play around with women.

“Apparently not.” Taehyung shrugged, “I tried telling her that he’s not what she thinks he is, but she didn’t listen.”

“She’s stupid! You could have told Jonghoon to back off! He can’t talk to her! She’s not realizing that fucker could slip his hand in her panties and fuck her! She’s not into those things! She’s not ready and she shouldn’t be anywhere near him” He exclaimed in anger.

“And why all of a sudden are you sounding like you care about Y/N?” Taehyung raised an eyebrow at him, he could sense the protection Jungkook had for you.

“You’re fucking crazy. I don’t give a crap about her. I’m just saying that she shouldn’t be talking to him because he’s not good for her at all.”

Taehyung hummed, but he wasn’t convinced, “Okay, whatever you say. But I can’t forget to add that she’s going on a date with him later this afternoon.” He smirked.

“WHAT?!” Jungkook looked at Taehyung as if his eyes could pop out of his sockets.

“Yeah, you heard me. A date. Where two people who are attracted to each other go and hang out to be romantic and shit like that.” Taehyung kept his little smile, waiting for Jungkook’s major defense mode.

“It’s definitely not an attraction or going to be romantic when really he’s gonna take her home and get in her pants.” He growled and his tongue poked out of his cheek, “She’s not going on that date. I have to go tell her this after I eat breakfast.”

It was around two o’clock in the afternoon and Jungkook took forever to find out where you were going on your date with Jonghoon. Jess could not answer his calls from her being occupied in the studio with Yoongi, Jonghoon wouldn’t tell Taehyung exactly where he was meeting with you, Jimin, Jin, and Namjoon had no idea of you going on a date. That was left with Hoseok who had been stuck in the 3J studio finishing his choreography for his first class tomorrow, had known exactly where you were going to meet Jonghoon. The Lounge Cafe.

It was a twenty minute drive but he didn’t care. He needed to find you and prevent you from hanging out with Jonghoon. When he arrived, the cafe was definitely modernized although that wasn’t the point. His eyes roamed the cafe from sitting in his parked car and that’s where they landed on a familiar girl wearing a cream floral dress, sitting alone outside at a table while reading a book. It was you.

With honesty, Jungkook thought you looked stunning. Maybe because he’s never seen you all dressed up. But your presence somewhat attracted him. His eyes read your look. The way your hair flowed from the light breeze, your adorable wide eyes blinking as you flipped a page, the way your posture is. Undoubtedly yet not realization, Jungkook always had thought you were beautiful without even saying you are. You are just naturally attractive. He wondered what life would have been if you weren’t so irking… or if maybe just things went the right way between you two. Would you two have become friends? Would there have been any feelings of? Well, that’s not that he would know of.

Before his thoughts could go any further to drive him away distractedly, he snapped out of them since he was here for a reason. Jungkook got out of his car, taking his keys, phone, and wallet and slipping them into his sweatpants as his made his way over to you, knowing of the arrangement with Jonghoon. When he reached you, he was already infuriated just as he took a seat in front of you, “Why are you wasting your time?”

You looked up from the page you were reading of your book to find Jungkook sitting right there with an incensed expression on his face. What the hell was he talking about? “Excuse me?” You questioned.

He let out a hollow laugh, “The guy isn’t worth the time, Y/N. Are you blind?” Your eyebrows knitted together in confusion, “You mean Jonghoon? How do you even know him?” Most of all, how did he know about this? Jungkook shook his head, “He is a friend of a friend I have. And he has a reputation Y/N. He doesn’t take too fondly to girls… that aren’t experienced.” His thumbs circled around each other as his fingers were interlocked.

You sighed, “And why do you care? You don’t know if he’s really like that, Jungkook.”

His eyes rolled in exasperation and looked at you, “Look Y/N, I know what I’m saying. I know that douche too well and you are just walking into one of his traps.” He nodded in assurance. “How did you even know about this?” You asked, “First of all, this is my business that you’re barging into. I don’t think he’ll even do such thing to hurt me.”

Jungkook leaned towards you, “He will use you for a bad purpose and break your heart, Y/N.” His voice deepened, “So don’t cry when he leaves you stranded and broken.”

You giggled, not believing him, “Please, he won’t.” You crossed your arms while leaning back on the chair, “And if that doesn’t work out and I end up wrong, then lesson learned. I like him.” You shrugged in yet confidence. Jungkook studied you in distaste with a hum, “You are so blind huh? Not just in sight but in judgment.”

That’s when you just had enough. What rights does he have to be telling you this? You were done kissing his ass, “Judgement? Who are you to tell me this? Why can’t I just like anyone for crying out loud? Are you that surprised at the fact I’m probably going to start dating?” You asked.

Jungkook nodded with no expression, “Obviously yes, as no guy would ever be interested in you anyways.” He shrugged as he sat back. You looked down in distress. It was true, but yet you just had a strong feeling that Jonghoon was actually interested in you, “At least it feels nice when someone is interested in me...” You said quietly.

“As if any guy would.” He said expressionlessly. You have yet nothing to say and he got the message that you were done listening. He got up from his seat as he looked at you with no sympathy, “Don’t blame me if he tears you apart.” And with that, he walked off. You sat there, not knowing what to think. You didn’t want to believe him because you were already over with him being an ass. He couldn’t be telling the truth… right?

The clear skies with shining sun soon faded when dark and grey clouds have flown into them. It would have been much better as a delight to maybe brighten up the day a little and not ruin it for you after what just clearly happened.

Jungkook on the other hand just did not care about what was going on with you and Jonghoon. Or does he because of the guy’s reputation with girls? No, that didn’t matter to him. If Jonghoon did anything to mess with you, then it was your fault for not listening to Jungkook. And he basically told you so. No fucks were given in the end.

At the end of practice at BigHit’s dance studio, Jungkook sat down on the floor with his back against the wall and grabbed his phone. Seeing an odd countless amount of messages from Jess, he was confused. She seemed worried and angry, but why was she?

Jess (4:33pm): Jungkook, idk where you are right now and honestly i don’t care but y/n hasn’t come home and i’m fucking worried.. Like seriously.

Jess(4:33pm): Can you look around and see if you can find her?

Jess(4:36pm): If you don’t, just know your hair won’t make it to the morning :)

Jungkook groaned in annoyance and responded.

Jungkook(5:02pm): Are you serious?? Do I really have to do this? Why can’t you just ask any of the other guys?

Jess(5:07pm): For one, Yoongi is at the studio but he is working on your comeback so he is out of the question. Hoseok is with Family at the moment, Jin is probably asleep, Jimin is out with Taehyung somewhere and Namjoon… I’m not sure where he is but you’re in her area and I need someone asap as my car is out of gas unless I’d be doing this shit my fucking self.

Jungkook(5:08pm) I could just give you money or bring gas to you. I literally have no idea where she is and I am nowhere in any mood to even find her.

Jess(5:12pm): See you’re the last fucking person I want to ask anyway but I need you to do this cause I’m working on something for Mr. Bang and if it’s not finished I am screwed. So just text Namjoon as he was the last one to talk to her after you decided to be an ass before her fucking date. Which I'm tempted to smack you for doing but you’re right about this guy which is why I'm extra worried… so just for my fucking sanity please jungkook. I’ll pay you back in whatever the fuck you ask for, games etc. just do it.

Jungkook(5:14pm): fine, but let this be the last fucking time you ask me to do something with y/n involved. I give no fucks about her or whatever she does with that douche just an FYI.

Jess(5:15pm): you can say that all you want but I know you Jungkook. Just find her, and if that fucker has hurt her tell me so I can plan his fucking funeral.

Jungkook(5:17pm): What is this, you’re not believing me now? In what aspect do you mean by knowing me? As if. But whatever, you can do whatever you want. If she ends up hurt, I’ll tell you. But it’s her fault and I don’t care anyway. She’s a stubborn pain in the ass and is the last person I ever want to put in my car no offense.

Jess(5:18pm): Whatever Jungkook, you act like a douche on purpose but I won’t argue with you as you’re just as hardhead as yoongi. So just find her, I have shit too before Mr. Bang has my head on a pike.

Jungkook(5:19pm): alright fine. I’ll keep you updated if I find her or not.

Jess(5:21pm): Thank you... You really don’t understand how much I am thankful that you are doing this. She is like a daughter to me. So yeah I gtg Mr. Bang is yelling at me now lmao

Jungkook(5:22pm): I mean I guess lol… I’m only doing this for you.

Jess(5:23pm): it won’t only be me in the end, but thanks.

Jungkook(5:23pm): no problem

Jungkook sighed in annoyance and hung up slipped his phone in his pocket. Do I really have to do this? Yes, of course, he does. He’s not that much of an ass to reject doing a favor for someone who needs it. And if Jess is that damn worried about you, then he may as well go out and find you. Jungkook grabbed his backpack and carries it on his back after putting his sweaty towel in and zipping it up. Walking out to his car, he thought to himself, what happens if he doesn’t find you at all?

During the car ride, he went to various places that he could in order to find you. Locations that may seem where you might be based on where you probably like to go. And he even went to the most random places too. He’s driven around everywhere in Seoul basically trying to find just you.

An hour passed and you were not found. Jungkook was in utter anger and stress that he’s wasted on time looking for you. He just wanted to go home badly to rest, and at that point for finding you everywhere, he’s given up. He shook his head and turned his car around to his way home. How was he going to tell Jess that he didn’t find you?

Although it was one question that he was focused on, there was another one that he just couldn’t help but keep thinking about the most. Is she okay?

The thought if it makes him worry a little. And it was odd. Where could you possibly be that you suddenly disappeared all day? Then suddenly while driving down a road, he found someone familiar walking on the sidewalk with their head down. Their outfit just seemed to look too much like what you were wearing earlier. Your figure and the way you walk even caught him off guard. With curiosity and hope, Jungkook slowly drove up close to get a better look of you, and as soon as he was just there, it was suddenly and thankfully you, walking with your head down.

To be sure of it, Jungkook rolled down his window and slowed down next to you, “Y/N?” The familiar voice caught you off guard and caused you to turn. Surprisingly, you found Jungkook in his black luxurious car right next to you. And it was definitely bad that he could see your face full of sadness and regret.

Jungkook, who was ready to pop off his madness and yell at you, studied your face. Your eyes were puffy and watery, your nose was red and cheeks were a peachy color. You had been crying and for some reason, his face softened. It was weird seeing you cry and it didn’t make him feel good inside at all.

“Go ahead, laugh at me.”

Jungkook stood there with trying to keep no expression on his face, but he only blinked, “I… I’m not going to,” he said quietly and he took a deep breath with his chest rising, “Get in, it’s gonna rain soon and Jess is worried sick.”

You shook your head with your arms still locked, and making no eye contact with him, “No thanks, I’m fine.” You turned to walk off in the same direction you were heading. That wasn’t until “Y/N please.” Jungkook watched you walk away. But you just kept walking. You knew you didn’t want to deal with him. But he wasn’t going to let you walk away from him.

“Y/N please stop.” His voice arose and it sounded quite like a demand. But that didn’t stop you from turning around with a pissed look on your face with tears streaming down your cheeks. “And why do you care?” And at that, Jungkook stays silent for a while.

You couldn’t be bothered to turn around to face him properly, for your insides were seething with rage and your heart felt empty to the core. Jungkook was right, he always was. The things he said to your face, how badly he spoke of you, and now this, about the guy who you thought was pretty decent—and something about Jeon Jungkook being right about everything is making your jaw clench in anger as you recall the buried grudge he has for you. Why must he keep meddling in your life? Right now, you wished he just disappeared off the face of earth. That way, your life would be much, much easier. You wouldn’t have to keep caring about your stupid feelings getting hurt and being the constant target and Jungkook’s antics.

And that’s the worst part. Feelings.

You’ve been harboring them for him god knows since when and you are afraid to open up about it to him. There’s this side of you Jungkook always fails to see and you doubt he ever will. Even if he does, it is highly unlikely that he would even care. And that is the question bothering you most as of the moment.

Why did he fucking care?

With your back facing him, you missed how he churns on his inner cheek and doesn’t know where to put his gaze. The rain pattering on the concrete floor didn’t provide him with the answers he needed. He directed the question back to himself and he realized he could not give closure as well.

With a sigh, he spoke, “Because I hate seeing you sad when it’s because of someone else hurting you like no one should or I shouldn’t.”

“I know you’re upset but can you please get in the car for my own good sake to get you home and save you from being sick at least?” Without a word, or looking at him, you walked past him and your shoulders barely touched as you walked to the passenger side of his car. That gave him a slight tingle in himself as he’s rarely been that close to you.

On the way back home, it was pure silence in the thin atmosphere. Jungkook gave glances to you here and there but you never once took a glimpse at him. And your position was obvious. You were sitting with your legs tightly closed and your fingers were brushing against each other as you only looked out the window, keeping your emotions as stable as you could. But it was so difficult to just give in and not cry. Then you realized, how could you be so stupid to not listen to him? He was right. You were angry. Not at Jungkook. But yourself. You felt bitchy. So bitter. Yet it was wrong to be that way to him. Although he has had a big hatred for you, you just can’t ever treat him the same. It just doesn’t work that way for you, which is a big problem. You’re too nice.

“He hurt you didn’t he?” His soft voice snapped you out of your thoughts, that you didn’t even realize he was already parked in front of your apartment. You gazed over at him and by the look on your face, Jungkook felt a little pang in his heart. Eyes puffy and glossy, your nose and cheeks peachy. He has never seen you cry once before, not even has he seen you express a sad or depressing emotion. He’s always seen you smile.

“Yes. And I let him.” Your voice cracked as if it hit the flu. Jungkook clenches his lips as he caught your eyes blink with tiny little tears, “What did he do?” You shook your head, “Just something that I learn my mistake from. It’s nothing-“

“Y/N” He started, “What did he do?” He stared at you with a straight face, almost like a demand. And it wasn’t that he was forcing you. He needed to know.

You sighed quietly as you could feel the slight order from him and you just couldn’t say no to him. “He groped me.” You vocalized in a shaky tone. Jungkook could feel his blood boil fast and kept calm, “Where did he touch you, Y/N?” His voice lowered.

“I c-can’t tell you-“

“If you can’t tell me, then point to where did he touch you.”

You gulped and your heart thumped rapidly, “Um…” You didn’t want any trouble at all and you were so hesitant in just telling him Jonghoon’s attempt to getting in your pants. But Jungkook could tell what he tried to do when you stuttered and look down at your most private area. As soon as you picked your head up at him, your tears were already swimming around your eyes, “H-He-“ you tried to speak but you were cut off by Jungkook’s hand grabbing you and pulling you onto his lap with your legs straddling him, in which you began to let out a breathy cry. His arms engulfed around your fragile figure and he held you tight in his arms, your response with burying your face in his neck with your hands on his hard chest as you sobbed in his neck.

But this was weird. You’re sitting on your enemy’s lap and he’s comforting you. He’s practically holding you in his own arms and you’re letting him. Ye his comfort made you feel safe… and you didn’t want to pull away. You didn’t even dare to. His soothing fingers stroking your hair as his hand rubbed your back slowly but keeping a light grip on you.

Jungkook on the other hand, he didn’t know what in the hell is he doing or what he was thinking. Why is he holding you? Why did he grab you and suddenly felt that he needed to protect you? He was in rage deeply inside and one of these days when he finds Jonghoon, he’ll make sure he doesn’t have his perfectly straight teeth.

You were glued to each other, the steady beat of his heart making you never want to open your eyes. Some nights, you’d lie awake just thinking about what he would say if he ever felt guilty about what he did and here it was. And somehow, it was so much more than what you asked for. But you also were wary. The bigger part of you, though, knew he was being sincere, that he held this crushing guilt over his head over what happened between you two for the past five to six years.

”You don’t deserve this,” he softly spoke up along a sigh, “You’re too special and fragile…” He added.

Wait what? You pulled away from his neck and looked at him, “What?” Your cold soft voice barely could be audible. Jungkook got a better glimpse of you up close—broken and terrified. And it sure damn stabbed his own heart deeply. He locked a piece of your hair behind your ear as he stared at you, “I know I was an ass to you earlier but I know that what I’m about to tell you is what I really mean to say. You’re too unique and wonderful for him. He’s nothing but a scumbag looking for a just a fuck and you don’t need that. You need and will get a guy who will treat you loyally and kindly with all of his love for who you are. Any guy would be lucky to have you, Y/N. Wait for him…the right one will sweep you off your feet.” His thumb rubbed your hip softly and the feeling warmed your skin.

You blinked. Is he really telling you this or are you just dreaming?

He sighed, “Just trust me.” He said softly. Jungkook reached his hand up to your face and wiped your tears gently with his thumb, “You’re so beautiful…” And it was true to him. Being this up close to you, he was able to see your flaws but they resembled how gorgeous you are. You shook your head, you didn’t believe that “I’m not that-“

“Yes, you are.” He cut you off, “Honestly, you’re so attractive and stunning, don’t tell yourself you’re not beautiful when you have seen yourself in the mirror.” He looked into your eyes, deep into them.

And you just didn’t know what else to say because his brown doe eyes caught you off guard. Neither of you could look away and it’s like your eyes were having a never lasting conversation with each other. You could feel your own pupils dilate the more you looked closely into his, and you could have sworn that his eyes looked at your lips then at you. But you also didn’t think he did. And at that moment, it was when you come to the realization of what was going on, causing you to clear your throat, “Um..” you hummed, which had Jungkook probably get the memo too. You looked down awkwardly as your mind was going crazy but you remained calm, “Thanks for the ride… and listening.” You said softly. Jungkook eyes darted elsewhere but you with a blank expression on his face, “Yeah,” he started, “No problem.” He said and he just sat there, his tongue poking out of his.

You slowly got off his lap to the passenger side and got out his car, grabbing your bag as you fixed yourself and closing the door afterward without saying a word. Making your way into your apartment, you didn’t dare to look back. After locking the front door, you leaned your back against it, questioning what just happened.

You almost kissed your enemy.

#jungkook x reader #jeongguk x reader #jungkook imagine #jungkook #jungkook smut #jungkook au #BTS jungkook #bts imagine #bts scenarios #enemies to lovers au #bts smut #her blooming flower #hbf

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juniperpublishers-imst · 3 years

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Caveability Assessment of a Hanging Overlying Massive Deccan Trap and its Effect on Underground

Abstract

Efficient and safe extraction of coal from underground mines require regular/smooth caving of the hanging overlying strata in goaf which is intended to fall. Sometimes presence of extremely difficult to cave massive strata (EDTCMS) having higher strength and thickness as immediate roof delays the natural caving and affect adversely the depillaring operation in underground mines. Such EDTCMS are found globally (India, China, United States, Czech Republic) with thickness varying to hundreds of meters characterised as igneous/sedimentary formations. It is found to be lying either just immediately above or after a certain parting from the coal seam. The latter is found more frequent to the former in coalfields of the world including India. Bulking factor plays a major role in filling the void by the falling of the partition between coal seam and EDTCMS. When a large overhang of EDTCMS is created in the void then their sudden breakage may generate issues like dynamic weighting, floor heaving, pillar spalling, coal bump/rock burst, goaf encroachment/pillar failure and air blast in and around the face. Dynamic weighting by a dolerite sill in the roof destroyed the integrity of almost half of the chock shields in less than 4 second at Churcha West Colliery, India. Various techniques have been adopted worldwide to deal with the issues due to EDTCMS like their pre-fracturing, induced blasting, leaving wider barrier pillars at the face, back filling and injection of grouting material into the mining-induced overburden. This paper presents a case study discussing issues of spontaneous heating and pre-mature collapse of pillars due to EDTCMS at Mathani Underground Mine.

Keywords: EDTCMS, Depillaring, Immediate Roof, Caving, Dynamic Weighting

Introduction

Usually, it is found that the immediate roof in underground coal mines mostly consists of shale, clay, sandstone and their intercalation with thickness varying from 0.1-10m. When coal is extracted below such roof then it keeps hanging in the void space (goaf) created. Such strata caves easily and regularly without creating high induced stresses after a certain exposure as experienced in Pinoura underground mine in India [1]. Initially, the hanging roof in goaf is supported from all the sides and acts as a strong beam, inhibits caving. After a certain exposure, the strong beam fails/caves in goaf to become cantilever which keeps caving regularly. It is the story when working under easily to moderate caveable strata where roof fall takes place regularly on certain exposure of roof span. Sometimes extremely difficult to cave massive strata (EDTCMS) of sedimentary/igneous rock type is present in the roof having higher strength and thickness in hundreds of metres, delays the natural caving and affect adversely the depillaring operation in underground mines. Such strata keep extending their span without caving in the void space created and leads to a major accident in the mine. It is found to be lying either just immediately above or after a certain parting from the coal seam (Figure 1). EDTCMS located after a parting from coal seam have lesser chances to affect towards the working due to the filling of the void by caving of the partition (Figure 1a). When EDTCMS is found just immediate of the coal seam then it keeps hanging over a large span in the void without any failure and transfers load towards the working resulting into issues of coal bump/rock burst (Figure 1b). Mostly it is found after a parting from the coal seam. When a large overhang of EDTCMS is created in the void then their sudden breakage may generate issues like dynamic weighting, floor heaving, pillar spalling, coal bump/rock burst, goaf encroachment/pillar failure and air blast in and around the face. There is an incident of dynamic weighting by a dolerite sill in the roof which destroyed the integrity of almost half of the longwall chock shields supports in less than 4 second at Churcha West Colliery, India (Table 1). Another incident of water inrush occurred followed by a coal and gas outburst during the drivages of the gate roads at the Haizi Coal Mine in China (Table 1). Load of the EDTCMS is mostly shared by the coal pillars and the parting between it and the coal seam keeps falling regularly. EDTCMS starts building high abutment load towards the working causing the premature collapse of coal pillars. Goodrich et al. [2] has studied the load transfer distance by EDTCMS in United States coal mines. Less studies are available on measurement of mining induced stress under EDTCMS in Indian coal mines.

The parting between the coal seam and EDTCMS caves in the void by the stress-induced fracturing or goaf blasting technique or fall under gravity. Further, when the hanging rock fragments’ separate from the overlying rock mass, there are likely chances of rotating these irregular sized and shaped fragments’ in the void space. As a result of falling on to the ground there is possibility of reduction in size of rock fragments. It results into an increase in volume as broken rock fragments do not lock with each other perfectly causing inefficient packing due to air gaps between them. This increase in volume of rock mass to the actual volume is called bulking factor (BF). Height of caved zone is mostly dependent upon the BF of overlying strata during depillaring of coal pillars. Bulking of rock by blasting is completely different phenomenon from the natural caving of rock. As per previous studies, BF of different rock mass is found to be ranging between 1.05 and 1.84. Thus, if the parting is enough to fill the void created by coal extraction then there is least effect of EDTCMS towards the working. Sometimes, bulking of the parting is not enough or thickness parting is not enough to fill the void after their caving in the goaf. In this case, EDTCMS keeps hanging over a large span creating several issues towards the working. Various techniques have been adopted worldwide to deal with issues due to EDTCMS like their pre-fracturing by high pressure water injection [3] or induced blasting [4] (Figure 2), leaving wider barrier pillars at the face, back filling and injection of grouting material into the mining-induced overburden [5] (Figure 2).

Mine Details

Mathani underground mine lies in the Thesgora block ‘A’ between the latitude 78054’37” to 78057’36” and longitudes 22013’17” to 22014’55”, located at Chhindwara district of Madhya Pradesh, India. This underground mine was explored during 1992 and mining activity started in 1994. It is situated about 27 km east of Parasia town in the Pench valley. The area exhibits a rugged terrain comprising hills and valleys. Seasonal nallah runs in the block and drains to either Gunar or Pench river. Mathani village has a population around 350 persons, which lies in the middle of the Mathani underground mine’s property in the northern boundary. The seam of Mathani underground mine has Degree II gassiness level with an incubation period of 3 months. A total of 11 coal seams/section viz seam/sections-IA, I(B+C), IIA, II/IIB, IIIB, IVA, VA, VB1, VB2, VB and VC in descending or der at different depths of cover are present in Mathani underground mine. Among these coal seams only three coal seams i.e. I(B+C), IIIB and VA are workable, and rest are unworkable due to their poor thickness and less span. Seam VA is present throughout the property and found in almost every borehole, whereas seams I(B+C) and IIIB are absent or having unmineable thickness in few boreholes. Depth of cover for seam I(B+C) is found to be varying between 60-168m and seam IIIB is between 69-162m. The parting between seam I(B+C) and IIIB is less than 9m (varying between 2-7m) and is being worked contiguously with superimposition (Figure 3). The parting between the Deccan Trap and Seam I(B+C) is varying from 2-60m and thickness of the Deccan Trap is varying from 40-150m as per the various available boreholes data. Seams I(B+C) and IIIB are contiguously developed into various panels with pillar size 21.30m x 25.50m and gallery size 4.2m x 3.0m. Depillaring with caving approach by conventional drilling and blasting method is being carried out in contiguous section at the Mathani underground mine, leaving a rib of 2.3m width in both the seams which is further reduced judiciously during retreat. Around 9 panels (1A, 1B, 1C, 1G, 1H, 1I, 1J, 1K, 1L) of seam I(B+C) (Figure 4) and 9 panels (3A, 3B, 3C, 3G, 3H, 3I, 3J, 3K, 3L) of seam IIIB (Figure 5) are depillared successfully. Deccan Trap (basaltic sill) having thickness varying between 40-150m (Figure 6), lying as overhanging roof in the caved goaves of seam I(B+C). Problem of goaf encroachment causing overriding of pillars, faced while caving of Panel 1M of seam I(B+C) which further caused pre-mature closure of this panel and subsequently 3M Panel of seam IIIB also. Further, it kept affecting the barrier pillars by inducing fracture from corners and subsequently working pillars in the Panel 1N. Barrier and working pillars are under continuous deformation (from the dip most side) due to the incidences happened in previous Panel 1M. It has encroached up to two rows of barrier pillars in Panel 1N creating issue of reserve loss and strata control. It is guesstimated that the Deccan Trap is almost unbreakable to cave for the formed void and the mining induced stress created by the depillaring of previous 9 panels of the seam I(B+C) is causing the instability issues of natural supports during the working in Panel 1N. Accordingly, it is planned to study the caveability of hanging overlying massive Deccan Trap in the goaf of seam I(B+C) and its effect at this mine. It is found during the working in seam I(B+C) is difficult due to the mining induced disturbance in the Deccan Trap. It is diluting the strength of the working and barrier pillars and encroaching and affecting the working area. This encountered problem of the mine forced to leave two rows of barrier pillars between the depillared Panel 1M and working Panel 1N. Further, it is also found that the working in Panel 3M of seam III B is becoming difficult due to failure of the parting between seam I(B+C) and IIIB but the pillars are still intact. Geo-mining details and required information are collected for assessment of caveability of hanging overlying massive Deccan trap in the inbye goaves and its effect at Mathani underground mine. Details of the studied problem is mentioned in this report.

Details of the Problem

The pillars are found to be spalling up to 1-1.5m from all the sides and it is more visible in the dip most side, when compared to that of rise side in the pillar. Further, it is increasing gradually, causing the gallery width to increase from 4.2m to more than 6m. The parting between Deccan Trap of thickness 40-150m and Coal Seam I(B+C) is varying between 2-60m. However, the thickness of this parting at the present working is around 10m only and the height of the working is 3m. This parting is mostly consisting of arenaceous (sandy) clay and coarse to medium grain sandstone with less bulking factor (BF). There is no evidence of goaf packing by caving of fragmented overlying strata. Usually, BF for coal measure formation is 1.1. Field investigation noticed in Panel 1N of coal seam I(B+C) that the roof deterioration is in V-shape form along dip-rise galleries (Figure 7) and is found to be a simple manifestation of instability in the gallery. Extraction of coal by conventional drilling and blasting further deteriorates and dilutes the competency of roof and pillar. There is no observation of any mining induced movement in the Deccan Trap but overriding of pillar and goaf encroachment has been experienced in Panel 1M after extraction of 5 pillars in a panel of 12 pillars. It is guesstimated that the observed dilution of barrier pillar strength in Panel 1N has happened due to the load transferred by the Trap. Further the same incident continued and caused to leave two rows of barrier pillars between Panel 1M and 1N. Local fall regularly occurred up to a height of 3 m after a goaf exposure varying from 77-87m2 and the goaf is found to be filled partially. Panel 1M started on 18-06-2018 and the working discontinued due to pillar crushing and then panel was sealed on 23-08-2018 (Figure 8). Only local fall was observed during working in this panel. No monitoring is being carried out by any instrument, which makes the study incomplete for understanding of the strata mechanics. Seam IIIB is a low height seam at a parting varying from 2-7m between seam I(B+C) and IIIB. It is being worked in contiguous section. This parting mostly contains coal seam II with alternating bands of shale sandstone. This parting is not stable due to its poor competency, mainly due to poor thickness of laminated formation (shaly sandstone and coal seam II). During the mine visit it is found that the roof (parting between the two seams) of seam IIIB is getting detached even around the intact pillar. The working in Panel 3M (Figure 8) is abandoned due to the encountered problems in Panel 1M of seam I(B+C).

Geology of the Area

The geology of the area is based on the geological report on exploration for coal in Thesgora Block ‘A’ P.K. Valley Coalfield, District Chhindwara Madhya Pradesh prepared by MECL in January 1989. The entire area is covered by basalt, Jabalpur moturs and barakars are concealed under the cover of basalt flows. The area exhibits a rugged terrain comprising many hills and valleys. The maximum and minimum elevation being 791.22 m to 727.61m respectively above MSL. The general geological succession has been proved by sub-surface details as obtained by boreholes drilled from time to time. Based on borehole data, the lithological formations present in the area under consideration have been summarised in Table 2. The exploration in Thesgora Block ‘A’ has confirmed existence of a total of 11 coal seams/ sections viz seam/sections-IA, I(B+C), IIA, II/IIB, IIIB, IVA, VA, VB1, VB2, VB and VC in descending order. The general sequence, thickness of coal seams and parting ranges are given in Table 3.

Description of coal seams

Seam I(B+C) is the youngest seam in the area. The depth range of the floor of this seam varies between 60.45-139.91m with thickness varying between 5.17-7.31m (most prevalent range being 6-7 m). Immediate roof contains dominantly shale and immediate floor contains sandstone mostly. Dirt bands varying from 0-0.3m is present in this coal seam. Seam II/IIB underlies seam I(B+C), at a parting range between 0.47-2.47m consisting mostly of sandstone with shale band. The parting of seam II/II B with underlying seam III B varies from 1.20-3.71m.

The depth of cover varies between 66.04-142.79m with seam thickness ranging between 1.50-3.50m (mostly 1.50-2.50 prevalent). Immediate roof and floor contain shale mostly. This seam is generally devoid of any dirt bands. Seam IIIB underlies seam I (B+C) at a parting ranging between 5-7m consisting mostly of shale with sandstone bands and coal seam-II/IIB. The parting of seam IIIB with overlying seam II/IIB is varying from 1.20-3.71m, which is dominantly consists of shale. Its depth range varies between 67.86-147.4m with seam thickness variation 1.74-2.28m (most prevalent 1.5-2.0m). Immediate roof and floor contain shale and sandstone respectively. No dirt band is present in this coal seam. Seam VA underlies seam IIIB at a parting ranging between 10-20 m generally. The parting in the considered area varies between 13-16m and is mostly consist of sandstone with thin shale bands. This coal seam lies below depth of cover ranging between 83.02-164.81 m with seam thickness varying from 2.37-6.82 m (most prevalent is 4-6 m). Immediate roof and floor of this seam are sandstone and shale respectively. No dirt band is present in this coal seam. From the above Table, it can be seen that out of these 11 coal seams/sections only four I(B+C), II/IIB, IIIB and VA attain workable thickness.

Method of Working

Based on geo-mining and financial considerations, the mine management has decided that all seams would be extracted by Bord and Pillar method, seam I (B+C) and III B would be worked contiguously and seam II is being left out due to low inter-seam parting. Parting between floor of seam VA and IIIB is about 16m and that of between seam IIIB and I(B+C) is about 8 m. This brings out a drift length of 60m up to III B and 90 m up to seam I(B+C). Upper seam I(B+C) is approached by two intakes drifts and two return drifts from the main dips via III B seam. Main dips are driven in seam V A from the surface. The working panels in both the seams are opened from these drifts and dips. Seam I(B+C) and IIIB are being worked contiguously as the parting between these two seams is less than 9m and thus the workings are developed as per Coal Mines Regulation 104 (CMR 1957) by prior permission from DGMS. Pillars in upper seam I(B+C) are coinciding vertically with the pillars of lower seam III B. Size of the pillars and galleries in these panels are developed as per Regulation 99 of CMR 1957. The length of a panel is kept around 600-800m, but the panel is divided into different sub-panels of around 100 m length and 75 m width based on the estimated production and incubation period. Seam III B is around 2.0m (a low height) thickness and is being extracted by B&P method. Seam I(B+C) is having thickness from 5-7m with relatively inferior coal in roof. The method of extraction adopted here in this seam is to split the pillar in two halves by a level split of 4.8m x 3.0m dimension. Dip slice of 3m height and 4.5m width is to be driven leaving a rib of 1.8m against the goaf. Coal in roof is blasted by drilling of holes on retreat with an interval of 1.2-1.5m spacing similar like Blasting Gallery method. Rib is also being reduced judiciously on retreat along with the roof coal.

Rock Mass Rating

As per the available documents with the mine management, the RMR of immediate roof for seam VA is 30.60 belongs to poor roof category and seam II is 31.5 belongs to poor roof category. RMR of immediate roof for seam I(B+C) is 37.26 belongs to poor roof category and seam IIIB is 34.02 belongs to poor roof category. The compressive strength of shaly sandstone present in immediate roof of seam I(B+C) is 12.00 MPa. The compressive strength of moist coarse-grained sandstone present in immediate roof of seam VA is 0.80 MPa. The compressive strength of shaly sandstone present in immediate roof of seam II is 2.70 MPa. The compressive strength of shaly sandstone present in immediate roof of seam II is 7.22 MPa.

Support System

In addition to the basic purpose of the support system, it is supposed to give sufficient free space for the movement of machineries. Accordingly, all development galleries are being supported by roof bolts with or without roof stitching. Few hydraulic props of 10t capacity are provided to cater the urgent need supports at the faces. All the galleries lying within 3 pillars from the pillar under extraction are kept supported by 1.5m long full column grouted roof bolts at spacing of 1.0 m between the bolts in a row and 1.0 m between the rows of bolts and strengthened with W-straps at a matrix 1.0m x 1.0m. The junction is supported by 25 % extra bolting along with four numbers of W-straps. Also, one wooden/steel chock at a suitable location without hindering in movement of LHDs is provided at the junction. To prevent side spalling the sides of 3 pillars from pillar under extraction including split and slices are supported with fixing of bolts of 1.5m length in the side wall at a grid spacing of 0.75m x 2.0m in three horizons all along. Whole pillar is strengthened with rope stitching and kept tightened with wooden laggings from the side. All the split and slice galleries are kept supported by 1.5m long full column grouted roof bolts strengthened with W-strap at a matrix 1.0m x 1.0m. In addition to the above supports, wooden chock or steel chocks topped with at least 30% wooden slippers are set alongside of the rib side at an interval of 2.4 m and one rows of props are provided in between the chocks in each slice. Ledges (V-shaped deformation) formed are supported by three bolts of 1.5m length with W-straps.

Caveability Index

Assessment of caveability of overlying strata is vital for the method of extraction and design of underground structures during pillar extraction. The caving nature of overlying roof strata during depillaring of a coal seam depends on their thickness and the uniaxial compressive strength. Previous experiences of working in underground mines have revealed that a thick, strong and massive stratum caves after a large suspension inside the goaf and develops large mining induced stress transfer distance towards the working. Whereas, a weak/laminated roof stratum caves regularly and smoothly without their much overhang.

Based on different field studies, the caving characteristics of overlying strata are quantified in terms of Caveability Index (I) [6], which is defined as:

Where,  = Uniaxial compressive strength in kg/cm2, l = Average length of core in cm and T = Thickness of the strong bed in m and the factor n has a value of 1.2 in the case of uniformly massive rocks with a weighted average of RQD of 80% and above. In all other cases n = 1. This value of I is to be calculated for roof thickness equal to 10 times of the height of extraction and the corresponding values are matched with the indices provided in Table 4 to decide the nature of caveability of a stratum. Generally, fresh core samples of the roof strata are procured and subjected to laboratory testing for an assessment of I to understand the caving nature of overlying strata. However, an assessment of I at different depillaring panels of mine is undertaken to judge the caveability of roof on the basis of the data provided by the mine management. Provided values of the physico-mechanical properties of overlying formations indicate that the strata between seam I(B+C) and Deccan Trap is easily caveable. However, Deccan Trap is difficult to cave due to their inherent strength and thickness.

Caveability of massive deccan trap and bulking factor

Based on the above-mentioned formulation, the Caveability of massive Deccan Trap comes to be around 5400, which is under category III (Roof caveable with difficulty). Further, looking at the thickness of the Trap, a considerable section of the overlying strata is found to be caveable with difficulty, which makes the final extraction under the shadow of dynamic loading too. In fact, if sufficient dimension of the void is provided to break the Trap under the condition then there is a strong possibility of dynamic loading, otherwise the pillar extraction in the seam going to constantly encounter excessive loading and an impending threat of global instability. The caveability of roof i.e. parting between seam I(B+C) and Deccan Trap comes to be around 1800 falls under category I (Easily caveable roof). Usually, bulking factor for Indian coal measure formations are taken around 1.1. The average thickness of coal seam extracted during depillaring is 6m including the extraction at the time of retreat in slices. The parting between seam I(B+C) and Deccan Trap varies between 2-60m. Generally, the thickness of parting between the coal seam and the Trap over the present working is estimated to around 10m only. However, as per the bulking factor estimation, the upper limit of the parting thickness is not away from the influence zone. Thus, it can be said that there is an effect of the Deccan Trap during depillaring with caving on the working for the existing parting thickness between seam I(B+C) and Trap. Such a geo-mining condition can be dealt by effective management of the Trap. This can be achieved either through its caving or through adoption of narrow panel extraction with a good design of the natural support. It is important to note here that the indirect increase in height of the pillars (especially pillar at the goaf edge and barrier pillar) during retreat for full height working is also a point to be considered during the design [7].

Effect of Deccan Trap on Mathani Underground Mine

Deccan Trap is a major issue in this mine due to its inherent strength and thickness and remains overhanging inside the goaf after caving of the immediate roof of seam I(B+C). The observed caving does not fill the entire cavity generated due to extraction of the thick seam under the massive Deccan Trap. The overhang of Trap is generating considerable potential energy, which in turn is causing excessive stress over the natural supports like barrier pillars. As the trap is still intact over different voids of the previous depillaring panels, the ongoing system of depillaring at this mine will keep facing the problem of pillar instability. The approach to overcome such situation can be implemented through design of squat barrier pillars for the heightened goaf and induced caving of the overhang Trap inside the goaf through long hole drilling and blasting also called destress blasting. As the coal seams are extensively developed, the scope of design of pillars is limited and the requirement of the squat pillars can be achieved through packing/filling some of the selected galleries by incombustible material like sand. A proper design of manner and dimension of extraction along with an increase in the efficacy of the barrier pillars may prove to be an immediate solution for the mine. Experienced local instability of the parting requires to be dealt with appropriate design of support system as the quality of the inter-burden strata is poor. Around 6m thick coal seam has been extracted (full thickness) in the previous 9 panels of the seams, which has changed the nature of barrier pillars from squat to slender (reduced width to height ratio). In Panel 1N, the parting between seam I(B+C) and Deccan Trap comes to be around 10m, and thickness of Trap is around 90 m. Such a less parting can play major role in creating dangerous condition of overhanging Deccan Trap causing pillars to fail (due to abutment load) and encroachment of goaf. Overriding of pillar and goaf encroachment has been experienced in Panel 1M after extraction of 5 pillars among 12. Further the same incident is repeated with two rows of barrier pillars of Panel 1N. Local fall occurred regularly up to a height of 3 m after a goaf exposure varying from 77-87 m2 and the goaf is found to be filled partially. Panel 1M started on 18-06-2018 and working discontinued due to pillar crushing then panel sealed on 23-08-2018, where the massive overlying Trap has played significant role [8].

Conclusion

Although underground coal mining requires site specific design from very beginning, the encountered geo-technical issues in depillaring at the Mathani underground mine is, mainly, twofold:

(i) indirect increase in extraction height (heightened goaf) and

(ii) difficulties involved in destressing the mined-out area as the existing Deccan Trap keeps overhanging inside the goaf.

As the coal seams are extensively developed so the design of natural support has slim scope for any major improvement in their efficacy. Deccan Trap is a massive formation whose thickness varies from 40-150 m, lying in the roof of seam I(B+C) in the mine. The parting between seam I(B+C) and Deccan Trap is varying from place to place. In Panel 1N, the parting between seam I(B+C) and Deccan Trap comes to be around 10 m and thickness of Trap is around 90 m. Such a less parting plays major role in creating dangerous condition of overhang, which in turn is causing pillars to fail and encroachment of goaf inside working, Further, it is found that partial extraction (2-3 m of coal seam thickness) to control the height of caving would help in avoiding any movement to be induced in Trap when parting between seam I(B+C) and Deccan Trap is less than 60 m. However, in this situation, the excessive loading of the pillar will exist. The other approach would be destressing of the worked-out area by breaking the Trap for caving. This can be achieved by a suitably designed larger dimension of the void and adopting induced fracturing through long hole drilling and blasting. The blasting can be done from the existing underground openings but requires special equipment and effort to execute it. The attempt of caving/destressing should be practiced in presence of the competent natural supports, especially the barrier pillars. The competency of the existing natural support can be achieved through introducing a favourable tri-axial confinement condition as the discrete side support of pillars may not be effective. Reduction in the height of the final extraction (i.e. depillaring) is also an option to overcome the strata control issues of the depillaring.

Previously, Panel 1M of seam I(B+C) has been abandoned after extraction of 50% coal (from 12 pillars) due to overriding of pillar by goaf encroachment. Parting displacement in roof of seam IIIB can be restricted by proper installation of supports for which goal-post type support and/or W-straps with roof stitching may prove to be a better option. Further understanding about the goaf encroachment could be established through field instrumentation and strata monitoring. When the mine management planned to extract coal from Panel 1N of the same seam, they experienced failure of barrier pillars, which could have been avoided through the presence of a squat barrier pillars. It caused to leave one more row of barrier pillars in Panel 1N. Any induced movement in Deccan Trap may create apprehensive condition in the working leading to loss of men, coal and machinery but it is not confirmed yet whether movement in Deccan Trap has been considerably been initiated or not. It is required to install geo-technical instruments like stress meters, auto warning tell-tale, multi-point extensometers, load cells, instrumented roof bolts in the workings at selected locations to avoid any dangerous situation due to movement of the Deccan Trap. Further, a strata control team to look after the recordings of the installed instrument to give warning about any dangerous and risky condition in the mine would help in strata management. Depillaring with stowing is another option for the site but it will affect productivity along with associated operational and financial implications.

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