采放比对煤与瓦斯突出危险性的影响

发布时间：2018-03-15 09:40

本文选题：放顶煤开采　切入点：采放比　出处：《安徽理工大学》2013年博士论文　论文类型：学位论文

【摘要】：放顶煤开采是十分重要的厚煤层采煤方法。煤与瓦斯突出(简称“突出”)煤层放顶煤开采在我国至今仍存在有利于抑制和增加突出危险性两种截然相反的学术观点；现行《煤矿安全规程》禁止突出煤层放顶煤开采及其采放比’确定依据也欠充分。本论文针对长壁式放顶煤开采采高一定不同采放比对突出危险性的影响进行了研究,以探索突出厚煤层放顶煤开采的安全性、可行性、存在问题及其防治对策,为其安全开采提供技术基础理论与依据。在调查突出厚煤层放顶煤开采及研究现状基础上,从瓦斯地质、工程技术两方面分析了突出影响因素,发现该采煤方法的采放比技术参数对突出的影响效应复杂。放顶煤、采煤机割煤及炮采落煤工艺对突出影响存在差异,采放比是主要敏感安全参数,而放顶煤工作面宽度、支架高低位顶煤方式、回采速度等因素处于从属地位。在总结长壁式放顶煤开采支承压力分布一般规律研究成果基础上,对初采期首轮放煤应力分布采用FLAC3D软件进行模拟,得到顶板来压前的初采期放顶煤围岩应力重新分布会导致采煤分层前、后方煤壁附近应力集中且工作面应力梯度有增大趋势；这与顶板来后的正常期随采高或采放厚度增加卸压区及集中应力区宽度增加、峰值应力集中系数及工作面应力梯度降低的趋势不同。针对放顶煤开采复杂动、静态力学作用过程,基于瞬态动力运动方程采用有限元ANSYS10.0瞬态分析模块分析了某矿煤系条件采高2.5m、采放比1：3的初采期和及正常期放顶煤的应力、应变及弹性能释放演化分布等力学特征,以及不同采放比、顶板来压对其力学特征效应,发现初次放煤过程附近10m应力随时间变化,不同采放比应力峰值分布在放煤附近6m左右,工作面前、后方煤壁附近应力梯度增大。初采期首次放煤所释放弹性能是第二次放煤的3.5倍左右；采放比增加,放煤口附近20m范围内释放弹性能增加。初采期首次放顶煤在相同时间内采放比在1：3范围内增加不明显；超过1：3范围,其弹性能释放增加显著。放顶煤在顶板初次来压、周期来压和正常回采期弹性能释放分别分布在工作面前方25m、30m、40m,工作面中部较两侧释放多,且随采放比增加而增大。顶板来压时弹性能释放具有集中性,初次来压是正常回采的两倍多,且比周期来压时多；工作面附近煤体位移在顶板初次、周期来压期间显著增加。正常回采过程弹性能释放集中在工作面前方20m,且随采放比增加增幅减缓、释放范围有增加趋势；同时,工作面卸压区宽度增大、应力峰值集中系数减小。基于初采期切眼简化为圆形巷道弹塑性、流变等理论分析：顶煤及切眼巷道两侧煤壁附近一定范围内产生卸压带；小采放比的顶煤处于切眼巷道卸压影响范围内时,放顶煤对突出危险影响小；反之,大采放比的顶煤处于切眼巷道产生的集中应力影响范围内时,放顶煤则增加了突出危险。此外,基于煤层瓦斯含量满足朗格缪尔方程、瓦斯流动过程等温且符合达西定律条件,建立了工作面煤层支承压力与瓦斯渗流随时间变化的三维方程,采用ANSYS10.0热分析模块对放顶煤工作面切眼巷道、初采期放顶煤瓦斯流动场时空演化分布特征进行模拟,发现切眼巷道瓦斯排放宽度约为采高3倍,初采期首次放煤过程附近产生的瓦斯压力梯度比第二次放煤的瓦斯压力梯度大,首采放煤突出危险较第二次放煤突出危险大。根据放数值模拟、理论分析及现场资料统计分析等综合研究,发现了采放比对煤与瓦斯突出危险性的影响规律。初采期,煤层厚度10m、采放比1：3以内,采放比对突出危险影响不大；超过此范围,采放比增加,突出危险性增大。正常回采期,采放比增大可以一定程度缓解地应力主导型突出危险。基于突出矿井两级“四位一体”综合防治技术体系,初步总结出突出煤层放顶煤开采合理巷道布置、开采工艺参数等安全开采技术,提出了放顶煤开采工作面预测新要求,并在现场应用取得了良好效果。放顶煤工作面预测钻孔应间隔10-15m布置两排分别控制顶煤与采煤分层,在切眼两帮及初次期工作面前方预测孔深不少于10m、正常回采期测孔6-8m。初采期放煤与采煤分别留10m、5m安全煤柱；正常回采过程预测超前及措施超前距较一般采煤工作面有所增加。
[Abstract]:The top coal caving mining in thick coal seam mining method is very important. The coal and gas outburst (referred to as "outstanding") top coal mining in our country there are still conducive to curb and increase the outburst of two opposite academic point of view of coal seam; coal mine safety regulations prohibit the current < > outburst coal seam caving coal mining and mining ratio "according to the paper. Also due to the full longwall top coal caving ratio of different high tsetse outburst danger was studied, in order to explore the thick seam caving coal mining safety, feasibility, problems and countermeasures, provide the technical basis for the theory and basis of the exploitation of its safety.
In the investigation of thick seam caving mining and research based on the current situation, from the two aspects of gas geology, engineering and technical analysis of the prominent influence factors, the method of mining caving ratio technology parameters on the effect of highlighting the complex influence of top coal caving, shearer coal mining and coal blasting mining technology on the influence of prominent differences the caving ratio is the main safety sensitive parameters, and coal caving face width, stand high and low top coal mining methods, factors of speed in a subordinate position.
At the conclusion of longwall top coal caving mining abutment pressure distribution of the general law on the basis of the results of the first round of the initial mining stage coal stress distribution by using FLAC3D software to simulate rock caving mining period, get the roof pressure before the initial stress redistribution will lead to stratification before coal mining, the coal wall near the rear of stress concentration and work the surface stress gradient increases; the normal period and after the roof caving mining with high or increasing the thickness of the pressure relief area and stress concentration zone width increases, the peak stress concentration coefficient and surface stress gradient decreasing trend is different.
For the top coal caving mining complex dynamic and static mechanical process, transient dynamic motion equation by finite element transient analysis of ANSYS10.0 module analysis of coal mine based on the condition of a high 2.5m, caving stress ratio 1:3 and the initial mining stage and normal period caving, strain and elastic energy release distribution mechanical characteristics and different caving ratio, the roof pressure on the mechanical characteristics of the effect, found the initial caving process near 10m stress varies with time, different mining ratio peak stress distribution in coal caving near 6m, in front of the working face, stress gradient near the rear wall. The increasing of coal caving mining period for the first time at the beginning of the release the elastic energy is about 3.5 times of the second coal caving; caving ratio increased, the release of elastic coal near the mouth of the range of 20m can be increased. The initial mining period for the first time top coal caving ratio is not obvious increase in the range of 1:3 at the same time; the scope of more than 1:3, the bomb The performance of the release increased significantly. Caving in the roof first weighting and periodic weighting and normal recovery period elastic energy release respectively in front of the working face of 25m, 30m, 40m, in the middle of working face is on both sides of the release of more than, with mining ratio increasing. The roof pressure when the elastic energy release is concentrated, the first time the pressure is two times more than the normal mining, and the ratio of cycle to pressure; working face coal displacement near the roof at the first time, during the period pressure increased significantly. Normal mining process of elastic energy release in front of the working face of 20m, and with the increase of mining ratio slowed down, release range is increased; at the same time working face, pressure relief zone width increases, the peak value of the stress concentration coefficient decreases.
The initial mining stage cut is simplified as a circular tunnel elastic-plastic analysis based on rheological theory: top coal and cut near the roadway on both sides of the coal wall within a certain range of pressure relief zone; small mining caving ratio in cut roadway pressure relief range, top coal caving has little influence on the anti outburst danger; the caving ratio in cut roadway the stress influence range of large mining caving coal increased outburst danger.
In addition, the seam gas content meet on the basis of the Langmuir equation, the gas flow during isothermal and conform to Darcy law, three-dimensional equation working face support pressure and coalbed gas seepage changes over time was established, using ANSYS10.0 thermal analysis module of the top coal caving working face roadway caving period, gas flow field distribution was simulated at the beginning of evolution mining, found cut Roadway Gas Drainage mining width is about 3 times higher, the gas pressure gradient of gas pressure gradient in the initial mining stage first coal caving process generated near more than second coal, the first mining caving coal outburst risk is second times the coal outburst danger.
Based on the comprehensive study of numerical simulation, theoretical analysis and field data statistical analysis, found the influence of mining on coal and gas outburst hazard ratio. The initial mining period, coal seam thickness 10m, caving ratio less than 1:3, caving ratio has little effect on outburst danger; more than this range, the caving ratio increases, the outburst danger increased. Normal mining period, caving ratio can be alleviated to some extent stress oriented outburst.
System of comprehensive prevention and control technology of outburst coal mine two "four in one" based on the preliminary summary of the outburst coal seam caving coal mining roadway layout reasonable, safe mining technology parameters of mining technique, the top coal caving mining working face prediction of the new requirements, and achieved a good effect in field application.
Caving drilling prediction interval should be 10-15m two row layout control of top coal and coal mining in two layers, and the initial period to help cut in front of the working face prediction of hole depth of not less than 10m, normal mining period measuring hole 6-8m. at initial mining period of coal and coal mining were 10m, 5m security coal pillar; normal mining process forecast and measures from the more general mining face increased.

【学位授予单位】：安徽理工大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TD713

【参考文献】