Deformation mechanism of surrounding rocks and key control technology for a roadway driven along goaf in fully mechanized top－coal caving face

The variation of the stress in the bolted surrounding rocks structure of the roadway driven along goaf in a fully mechanized top-coal caving face with moderate stable conditions are studied by using numerical calculation. The essential deformation characteristics of the surrounding rocks in this kind of roadway are obtained and the key technology of bolting sup-port used under these conditions is put forward.     

Study on rock burst of fully mechanized sublevel caving mining in deep mine

The theoretical analysis, numerical simulation and field observation were used to study distribution characters of abutment pressure of fully mechanized sublevel caving face in deep mine, fully mechanized sublevel caving and pressure relief in entries along goaf to the influence of rock burst. The results show that： （1） With the increasing of mining depth, the abutment pressure zone is larger, its peak point is transferred to the front of face, the danger area occurring rock burst in the two fully mechanized sublevel caving entries is larger, and its position is far from the face; （2） There is larger failure area in the upper coal in front of the fully mechanized caving face, and strata possibly occurring rock burst transferred to the upwards or far from faces because of the main roof＇s buffer effect to the dynamic pressure burst, then possibility and strength reduced; （3） The position occurring rock burst is stress concentration zones （abutment pressure along the goaf and residual tectonic stress） and zones with geological structure; （4） Strenuous activities of roof is the inducing factor occurring rock burst.     

Study on fasART neuro-fuzzy networks for distinguishing the difficulty degree of top coal caving in steep seam

Introduction The sub-level roadway top coal caving is a new method to mining medium-thick and thick seam in the steep seam mines, and technical characteristics of this method are to divide the coal seam into several fields according to certain height(15~25 m) along inclined direction of the seam. A horizontal caving roadway is laid near the roof of the coal seam at the bottom of each sub-level mining field. Small holes for drawing coal are symmetrically laid at the side of the horizontal roadw…     

Numerical simulation and actual research on safety and suitable position of roadway driving along next goaf

In view of the stress concentration problem left by the joint coal seams mining since the reservation of the coal pillar, it was proposed that non-pillar mining technology be used in Dongrong No.2 coal mine.The numerical simulation software FLAC~(2D) was used to draw the relationship between surrounding rock deformation of roadway driving along next goaf and the size of the coal pillar, so the safety and suitable position of roadway was determined.The distribution of lateral abutment pressure was measure...     

THE BASIC MECHANICS PROBLEMS AND THE DEVELOPMENT OF LONGWALL TOP-COAL CAVING TECHNIQUE IN CHINA

Since the middle of 1980‘s, the longwall top-coal caving technique has developed rapidly in China. At present, it is one of the main approaches in the thick coal seam mining. This paper describes some mechanics problems of the caving technique, such as the damage and failure of the top-coal, the strata behaviors in the caving face, and the relation of the support and the surrounding rock. In order to employ the caving technique in a widespread scope, the problems such as the caving technique in the hard coal seam, the moving and running of the loose top-coal,and the upper floating of the gas etc. should be systematically studied.     

Study on ascending mining roadway layout of close distance coal seams in deep mine

To solve the problems appeared in mining process of No.2 seam, the ascending stress-releasing mining method was adopted. Studying on the reasonable layout of actual mining roadway in upper coal seams is the precondition of successful ascending mining. By using ＂device of leak measuring by blocking up double ends＂, it detected the height of overburden water flowing fractured zone originated from sub-coal seams mining. Thus it proved that the actual mining roadway of No.2 upper ascending seam was located in the smooth sagging zone. On the basis of analyzing the stress-releasing effect of sub-coal seams mining to upper coal seams by using RFPA software, it analyzed the stability of up-face coal seams and the reasonable location of starting cut in up-face coal seams. It also analyzed the reasonable gateway location in upper coal seams, which ensured the crossheading in upper coal seams out of the effect of sub-coal work face mining by using theory of underground pressure. Meanwhile, the reasonable pillars dimensions in upper coal seams by building the structure mechanics model of stope were researched. It can make the roadway driven along next goaf to be located in low stress zone, and be beneficial to keeping roads stable owing to less stress of surrounding rock. Finally, it tested the rationality of the layout method of roads in upper coal seams by engineering field measurement in 3221 working face.     

Mating model on production capacity for the system of cutting coal and drawing top-coal in FMMSC

Being a safe and highly-efficient mining method, fully mechanized mining with sublevel caving （FMMSC） was extensively employed in Chinese coal mines with thick seam. In order to make drawing top-coal furthest to parallel work with shearer cutting coal, decrease failure ratio of rear scraper conveyor and increase safe production capacity of equipments, based on production technology, set up the mating model of safe production capacity of equipments for the system of drawing top-coal and shearer cutting coal in coal face with sublevel caving. It is mean capability of drawing top-coal adapted to the capability of shearer cutting coal in a working circle in the coal face that was deduced. The type selection of equipment of rear scraper conveyor can be tackled with this mating model. The model was applied in FMMSC in Yangcun Coal Mine, Yima Coal Group of China. With the mating light-equipments, the coal output in coal face attained 1.05 Mt in 2004. It gained better technical-economic benefit.     

Analysis on characteristics of damaged field of surrounding rock and face of FMTC

Numerical simulation-FLAC~(3D) and equivalent material simulation were carried out to analyze the damaged patterns and lows, distribution of plastic width of face, and surrounding rock of FMTC during the advance of work face with different thick coal seams based on engineering geology and exploitation technology of 1151(3) fully mechanized top-coal caving (FMTC) face in Xieqiao Colliery.The results show that there is damage,and the destruction characteristics of surrounding rock and coal mass are differe...     

Surrounding rock deformation regularity of roadway under extremely complicated geological conditions in deep mine and its control

By combining the practices of deep mine mining in Changguang Mine field and using the Universal Distinct Element Code 3.0 (UDEC3.0) numerical computing method, the distribution characteristics of deformation field and stress field as well as the surrounding rock deformation regularity of soft rock roadway are analyzed under extremely complicated geolog-ical conditions, a technical principle of bolting to control the surrounding rock of roadway is put forward. And also using a dynamic control for surrounding rocks designing method, the supporting parameters and implement plan are rationally determined. The experimental tests have obtained a good controlling result of surrounding rock.     

Study on gob-side entry retaining technique with roadside packing in longwall top-coal caving technology

Pointed out some technical difficulties of gob-side entry retaining with roadside packing in Iongwall top-coal caving technology (LTCT), and analyzed the function mechanism of roadside filling body. Theory analysis shows the mechanical properties of high water material fit for the feature of deformation of gob-side entry retaining in LTCT, and gob-side entry retaining in LTCT face is one of effective ways to increase the recovery ratio of mining district.     

综放沿空掘巷底板力学机理与控制技术研究

针对谢桥煤矿沿空掘巷底板变形严重问题,在沿空掘巷整体力学环境分析的基础上,建立了底板力学模型,通过对底板失稳机理的分析,指出综放工作面沿空掘巷底板破坏主要是实体煤帮高应力的作用,控制的关键是加强实煤体帮、底角和窄煤柱的支护。这一思想在1101(3)综放面沿空掘巷实践中取得了很好的支护效果。     

特厚煤层综放沿空掘巷小煤柱合理宽度综合确定方法

为解决特厚煤层综放开采大煤柱尺寸下煤炭资源损失量大、沿空掘巷小煤柱合理宽度确定方法单一、研究结果与工程实际存在较大差距的问题,本文以扎赉诺尔矿区灵东煤矿为工程背景,提出了基于JW-6型地下高频电磁波CT系统、钻孔应力监测系统、数值模拟等多手段下特厚煤层综放沿空掘巷小煤柱合理宽度的综合确定方法,并依据此方法分析了灵东煤矿特厚煤层综放开采侧向支承压力分布规律及演化规律、煤柱承载及变形特征,以此确定了灵东煤矿特厚煤层综放沿空掘巷小煤柱合理宽度为6.0～9.0m。工程实践结果表明,该综合分析方法确定的特厚煤层综放开采小煤柱宽度合理,回采期间巷道围岩变形量绝大部分控制在300mm以内,变形量小,满足工作面安全生产需要,提高了煤炭资源回收率。该研究成果对特厚煤层综放沿空掘巷小煤柱合理宽度的确定具有重要参考意义。     

综放沿空掘巷围岩大、小结构的稳定性原理

针对综放沿空掘巷围岩的特点,提出了综放沿空掘巷岩大、小结构的稳定性原理,为锚杆支护的成功应用提供了理论依据。对中老顶中的弧三角形关键块的受力特点、在掘巷期间和回采影响期间的稳定情况以及对其下的沿空掘巷的影响进行了分析。探讨了影响围岩小结构稳定性的主要因素;应用巷道锚杆支护围岩强度强化理论,研究了提高锚杆预紧力和支护强度对保持围岩小结构稳定性的重要意义。     

深井综放工作面沿空顺槽超前支架应用及效果

为了解决深井综放工作面沿空顺槽超前支护难题,分析沿空面侧向岩层结构及综放面沿空顺槽支架–围岩关系,建立确定沿空顺槽超前支护强度的力学模型,针对ZQ5200/21.5/45型超前液压支架的特征、工作阻力变化情况、沿空顺槽表面位移观测结果,验证了支架选型的合理性,可以有效控制沿空顺槽巷道围岩变形。     

上隅角埋管抽放前后采空区瓦斯运移规律研究

针对新安煤矿14211沿空留巷综放开采工作面上隅角瓦斯浓度超限问题,对综放开采工作面采空区瓦斯运移规律进行了研究。根据CFD数值模拟的理论,建立采空区瓦斯渗流的三维非均质模型,并得到了模型中相应参数的确定方法。利用Fluent数值模拟软件,对比分析了沿空留巷综放开采工作面上隅角瓦斯有无情况下的采空区瓦斯运移及浓度分布规律。模拟结果表明:通过上隅角瓦斯抽放可平均减少42%的上隅角和采空区的瓦斯,有效解决了沿空留巷综放开采工作面上隅角瓦斯积聚问题,从而保障了综放开采工作面的安全生产。     

窄煤柱综放煤巷钢梁桁架非对称支护机理及应用

针对王家岭煤矿窄煤柱综放煤巷围岩控制难题,分析指出相邻大型综放工作面覆岩剧烈活动及其基本顶对巷道区域直接顶的倾斜挤压力是导致顶板产生水平移动和非对称破坏的本质原因。建立考虑基本顶对直接顶倾斜挤压应力的窄煤柱综放煤巷直接顶力学模型,得出巷道顶板最大变形区域(7.5≤x≤9.5 m)。研发了以钢梁-槽钢组合结构和多根锚固至顶板纵深处锚索为关键部件的多锚索钢梁桁架系统,阐明其控制原理。建立多锚索钢梁桁架非对称支护的力学模型,得出非对称弯矩减小量分布特征,探讨其与非对称变形的一致性,并结合现场实践确定控制方案。现场实践表明,20103运输巷采用钢梁桁架非对称支护技术后,围岩变形量均控制在安全范围内,实现了对窄煤柱综放煤巷围岩非对称变形破坏的有效控制。     

南阳坡煤矿8800综放工作面临空小煤柱尺寸研究

针对南阳坡煤矿8800综放工作面沿空掘进巷道临空小煤柱合理尺寸进行了深入、系统研究。基于关键层理论,构建临空煤柱顶板关键岩块铰接结构力学模型,数学推导煤柱承载应力,结合Bieniawski提出的煤柱强度线性计算方法,确定沿空掘巷临空小煤柱宽度为7m。采用相似实验模拟沿空掘巷临空7m小煤柱围岩的稳定性,并开展巷道表面位移现场观测试验,结果均较为理想,验证了8800综放工作面沿空掘巷留设7m临空小煤柱的可行性。为类似开采条件沿空掘巷临空小煤柱尺寸确定提供了参考和借鉴。     

特厚硬煤层综放开采合理区段煤柱尺寸研究

 水帘洞煤矿3801综放工作面地质条件极其复杂,合理确定区段煤柱是实际遇到的工程难题。通过采场前后方侧向应力场与位移场在线观测,获得了综放沿空实体煤侧向应力分布规律及变形情况;通过数值模拟得到了不同煤柱尺寸沿空实体煤侧向应力分布变化规律。综合分析得到了合理煤柱留设尺寸,为彬长矿区同煤系特厚硬煤层综放开采确定合理煤柱尺寸提供了科学依据。     

综放沿空巷道不对称破坏特征及其原因分析

随着我国综放条带式开采的推广,留煤柱护巷的沿空留巷技术成为主要布置方式之一,但是也出现了矿压的不对称显现等新的围岩控制问题。在深入调研统计的基础上,详细阐述了宽煤柱护巷和窄煤柱护巷条件下,综放沿空留巷的变形破坏时间和特征,并进一步分析两种情况下的变形破坏原因。宽煤柱护巷不对称变形破坏原因为煤柱宽度留设不足和垂直应力的非对称分布,窄煤柱护巷不对称变形破坏的原因为采动影响形成的水平应力和侧向支承压力的分布不均。