Development of 3D top coal caving angle model for fully mechanized extra-thick coal seam miningOA

During high-intensity, fully mechanized mining of extra-thick coal seam, the top coal would cave to a certain 3D form. Based on the data collected during drilling, a 3D model of top coal caving surface space was established to determine the relationship between the location of the stope roof and the caving surface,enabling the mathematical computation of the top caving angle(φ). The drilling method was employed to measure the top caving angle on two extra-thick fully mechanized coal caving faces...     

“三软”极不稳定煤层综采技术研究

偃龙矿区开采的山西组二．煤层属于“三软”极不稳定煤层,其突出特征为煤层松软、厚度和倾角变化大,顶板及底板松软、破碎,赋存条件复杂,开采极其困难．嵩山煤矿以多项支护技术专利为支撑,采用底板岩巷的“一巷三用”,合理选择高强度轻型放顶煤支掩式液压支架,以及综采防片帮和防冒顶等技术,实施综采机械化开采,实现了“三软”煤层的安全高效开采,取得了显著效果．     

Effect of protective coal seam mining and gas extraction on gas transport in a coal seam

A gas–solid coupling model involving coal seam deformation,gas diffusion and seepage,gas adsorption and desorption was built to study the gas transport rule under the effect of protective coal seam mining.The research results indicate:(1) The depressurization effect changes the stress state of an overlying coal seam and causes its permeability to increase,thus gas in the protected coal seam will be desorbed and transported under the effect of a gas pressure gradient,which will cause a decrease in gas pressure.(2) Gas pressure can be further decreased by setting out gas extraction boreholes in the overlying coal seam,which can effectively reduce the coal and gas outburst risk.The research is of important engineering significance for studying the gas transport rule in protected coal seam and providing important reference for controlling coal and gas outbursts in deep mining in China.     

软煤层巷道支护数值模拟研究

针对新义煤矿11011工作面回采巷道煤层松软、围岩变形大、现有微拱工字钢支护难以满足生产安全需要的问题,利用FLAC数值模拟软件分别对微拱工字钢和外扎腿U型钢支护下的巷道位移矢量特征、应力特征及塑性区范围进行了分析．结果表明,外扎腿u型钢支护,能有效地改善围岩的应力状态和控制围岩的变形量,适合该矿软煤层特征;通过对12011皮带运输巷进行的工业性试验的实测变形数据分析表明,外扎腿u型钢支护,降低了顶板与两帮收敛速度与位移,提高了软岩巷道围岩强度和自承能力,维护了巷道围岩的稳定性,支护效果良好,能满足新义煤矿安全生产的要求,可为类似条件下的巷道支护提供参考．     

碱土加固注浆材料试验及其工程应用

在碱土注浆加固的基础上,对一种注浆加固材料的主要性能参数及其在静水条件下的材料特性进行室内试验研究。基于现场施工对材料胶凝时间和加固强度的要求,测定材料在不同配比下的胶凝时间,结合力学性能试验测定材料的净浆结石体强度及岩土固结体强度;针对加固治理的材料要求,测定材料在不同静水条件下的耐久性和稳定性,并与其他注浆材料进行了比对分析。依据材料性能和张马屯铁矿泥质破碎带的特点,系统阐述了材料的应用方法与效果。研究结果表明,该材料的胶凝时间精确可调,净浆结石体强度及岩土固结体强度均较高,耐久性和稳定性良好。     

煤层注水促抽瓦斯及其影响因素的数值模拟

为有效预防煤矿瓦斯灾害,获取煤层注水促抽瓦斯的合理参数,以常村煤矿2103工作面为例,依据多相渗流理论,采用Fluent软件的VOF模型及多孔介质模型耦合求解,对煤层注水促抽瓦斯技术及其影响因素进行数值模拟,并将模拟结果应用于现场,对比分析数值模拟与现场实测数据,二者基本吻合.研究结果表明:煤层瓦斯含量以注水孔为中心径向逐步降低,以抽采孔为中心径向逐步升高;注水前抽采阶段,随着抽采时间的增加,抽采范围逐渐增大,抽采孔瓦斯流量先快速下降,后逐步缓慢降低;注水促抽阶段,随着注水时间的增加,注水范围逐渐增大,注水流量逐步降低,煤层瓦斯含量缓慢升高,抽采孔瓦斯流量逐渐增加;注水后抽采阶段,随着抽采时间的增加,压力水覆盖范围持续增大,煤层瓦斯含量逐渐降低,抽采孔瓦斯流量逐渐减小.注水时机、注水时间、注水压力、注水方式、布置方式及钻孔间距是影响煤层注水促抽瓦斯效果的6个主要因素.瓦斯正常抽采20 d后,按照一注一抽方式及5 m间距布置注抽钻孔,在8 MPa煤层注水压力下间歇注水10 d,煤层注水促抽瓦斯效果较好.     

Feasibility analysis of gob-side entry retaining on a working face in a steep coal seam

Based on the decline in exploitation of coal resources, steep coal seam mining and mining face tensions continue to explore the feasibility analysis of steeply inclined faces in the gob. One of the key factors in utilizing the technology of gob-side entry retaining in steep coal seams is to safely and effectively prevent caving rock blocks from rushing into the gob-side entry by sliding downwards along levels. Using theoretical analysis and field methods, we numerically simulated the mining process on a fully-mechanized face in a steep coal seam. The stress and deformation process of roof strata has been analyzed, and the difficulty of utilizing the technology is considered and combined with practice in a steep working face in Lvshuidong mine. The feasibility of utilizing the technology of gob-side entry retaining in a steep coal seam has been recognised. We propose that roadways along the left lane offshoot body use a specially-made reinforced steel dense net to build a dense rock face at the lower head. The results show that the lane offshoot branch creates effective roof control, safe conditions for roadway construction workers, and practical application of steeply inclined gob.     

Rock parameters inversion for estimating the maximum heights of two failure zones in overburden strata of a coal seam

In order to enter effective parameters of rock mass in a numerical model, the relationships between mechanical parameters of rock and rock mass were obtained by an inversion method and an orthogonal test, given our measurements of the maximum heights of two failure zones in the Longdong coal mine.Using the maximum heights of the caving zone and the water-conducting fractured zone as test indices the modulus of elasticity, the Poisson ratio, cohesion and tension strength as test factors and different values of reduction enhancement factors as test levels, an orthogonal test was designed to obtain an optimum simulation scheme. From the analysis of different values of reduction enhancement factors which affect the test indices, an optimum factor combination for modification of parameters could be inferred. By using modified parameters in our numerical simulation, the maximum heights oftbe caving zone and the water-conducting fractured zone in the extensive Xiyi area were determined as 15.06 m and 36.92 m. These values were almost the same as those obtained by similar material simulation (8.5 m and 37.0 m) and empirical prediction (8.4 m and 34.4 m). These results indicate that the modification of parameters is a rational method.     

晋城矿区东部9号煤层及其顶底板岩性的研究

通过对 9号煤层及其顶底板岩性的研究 ,得出如下结论 :9号煤层煤层厚度变化很大 ,但层位稳定 ,在现代开采技术条件下应属大部可采煤层 ;9号煤层顶板K4灰岩厚度不稳定、相变大 ,须注意小于 0 .5m厚度顶板范围及相变部位的顶板管理 ;9号煤层底板为高岭石粘土岩 ,遇水易膨胀底鼓 ,对综采机械化生产可造成影响     

Arch structure effect of the coal gangue flow of the fully mechanized caving in special thick coal seam and its impact on the loss of top coal

Based on the characteristics of the top coal thickness of the fully mechanized caving in special thick coal seam,the long distance of coal gangue caving,as well as the different sizes of the coal gangue broken fragment dimension and spatial variation of drop flow,this paper uses laboratory dispersion simulation experiment and theoretical analysis to study the arch structure effect and its influence rule on the top coal loss in the process of coal gangue flow.Research shows that in the process of coal gangue flow,arch structure can be formed in three types:the lower arch structure,middle arch structure,and upper arch structure.Moreover,the arch structure has the characteristics of dynamic random arch,the formation probability of dynamic random arch with different layers is not the same,dynamic random arch caused the reduction of the top coal fluency;analyzing the dynamic random arch formation mechanism,influencing factors,and the conditions of instability;the formation probability of the lower arch structure is the highest,the whole coal arch and the coal gangue arch structure has the greatest impact on top coal loss.Therefore,to prevent or reduce the formation of lower whole coal arch structure,the lower coal gangue arch structure and the middle whole coal arch structure is the key to reduce the top coal loss.The research conclusion provides theoretical basis for the further improvement of the top coal recovery rate of the fully mechanized caving in extra thick coal seam.     

Pressure relief, gas drainage and deformation effects on an overlying coal seam induced by drilling an extra-thin protective coal seam

Numerical simulations and field tests were used to investigate the changes in ground stress and deformation of, and gas flow from, a protected coal seam under which an extra-thin coal seam was drilled. The geological conditions were: 0.5 meter min-ing height, 18.5 meter coal seam spacing and a hard limestone/fine sandstone inter-stratum. For these conditions we conclude: 1) the overlying coal-rock mass bends and sinks without the appearance of a caving zone, and 2) the protected coal seam is in the bending zone and undergoes expansion deformation in the stress-relaxed area. The deformation was 12 mm and the relative defor-mation was 0.15%. As mining proceeds, deformation in the protected layer begins as compression, then becomes a rapid expansion and, finally, reaches a stable value. A large number of bed separation crannies are created in the stress-relaxed area and the perme-ability coefficient of the coal seam was increased 403 fold. Grid penetration boreholes were evenly drilled toward the protected coal seam to affect pressure relief and gas drainage. This made the gas pressure decrease from 0.75 to 0.15 Mpa, the gas content de-crease from 13 to 4.66 m3/t and the gas drainage reach 64%.     

Evaluation of gas production from multiple coal seams: A simulation study and economics

Gas production from multiple coal seams has become common practice in many coal basins around the world. Although gas production rates are typically enhanced, the economic viability of such practice is not well studied. In order to investigate the technical and economic feasibility of multiple coal seams production, reservoir simulation integrated with economics modelling was performed to study the effect of important reservoir properties of the secondary coal seam on production and economic performance using both vertical and horizontal wells. The results demonstrated that multiple seam gas production of using both vertical and horizontal wells have competitive advantage over single layer production under most scenarios. Gas content and permeability of the secondary coal seam are the most important reservoir properties that have impact on the economic feasibility of multiple seam gas production. The comparison of vertical well and horizontal well performance showed that horizontal well is more economically attractive for both single well and gas field. Moreover, wellhead price is the most sensitive to the economic performance, followed by operating costs and government subsidy. Although the results of reservoir simulation combined with economic analysis are subject to assumptions, multiple seam gas production is more likely to maintain profitability compared with single layer production.     

Experimental research of overburden movement and subsurface water seeping in shallow seam mining

Shallow seam coal field has the largest coal reserve in China. Mining in shallow depth causes serious problems, and sub- surface dewatering is a major issue. In this paper, the physical simulating models were prepared to study overburden movement and aquiclude stability in the shallow seam mining of Yushuwan Coalfield, China. According to the characteristic of clay aquiclude and bedrock in the overburden, the proper simulation materials for simulating the plastic clay aquiclude layers and brittle bedrock layers were determined by the stress-strain tests and hydrophilic tests. The physical simulating models of solid medium and two phases of solid-liquid medium were carried out to simulate the failure and caving process of the roof and overburden, as well as the subsurface water seeping. Based on the simulation, it was found that the movement of clay aquiclude follows the movement of the underlying bedrock layers. The stability of aquiclude is mainly affected by cracks in fracture zone. The tests also showed that the best way to control the stability of aquiclude is to reduce the subsiding gradient, and there is a possibility of ground water conservation under longwall mining in Yushuwan Mine. This research provides a foundation for further study on mining dewatering and water conserva- tion.     

分形理论及其在材料科学研究中的应用

从分形的一般概念、分形体的数学构造、分形的维数、分形的自相似4个方面简要介绍了分形理论,综述了分形理论在材料学中的断裂、磨损、疲劳方面的应用。     

Dynamic destabilization analysis based on AE experiment of deep-seated, steep-inclined and extra-thick coal seam

No. 5 coal seam in Huating Coal Mine is a deep-seated, steep-inclined extra-thick coal seam where excavation disturbance is quite frequent. The maximum and minimum principal stresses differ widely. During mining, dynamical destabilization happens frequently and induce tragedies. Based on the comparison between the acoustic emission （AE） experiment on dynamical destabilization of coal rock and the related in situ testing results, this article provides comprehensive analysis on the regular quantificational AE patterns （energy rate, total events） of coal rock destabilization in complex-variable environment. The comparison parameters include dynamic tension energy rate, deformation resistance to compression, and shear stress.     

掺入工业废料的改性生土材料抗压试验

为合理利用废弃材料改善生土材料力学性能,通过在素土中掺入糯米浆、废玻璃渣和橡胶,形成改性土体材料,设计5种配合比方案,制作Φ102 mm×116 mm圆柱体试块。通过对其进行轴心抗压强度试验,对比不同配比试件的试验现象、抗压强度、变形能力、荷载位移曲线,分析不同掺合料的作用机理、研究不同掺料不同掺量对抗压强度的影响规律,提出了玻璃渣和橡胶掺量的合理范围。试验结果表明,在素土中掺入糯米浆能提高素土抗压强度,掺入糯米浆、玻璃渣和橡胶,可提高抗压强度和变形能力,但其抗压强度随玻璃渣和橡胶掺量的增多增至3.12 MPa后下降。     

岩石隧道渗流模型试验相似材料的研制及应用

为提高岩石隧道渗流场分析的合理性,通过大量以控制渗透系数为核心的配比试验,提出适用于岩石隧道渗流模型试验的围岩、注浆圈及初衬等新型相似材料及其原料配比.试验以黏土、细砂和玻璃纤维为原料配制围岩相似材料,以水泥和炭渣配制注浆圈相似材料,由多层编织土工布模拟初衬相似材料.结果表明:随细砂含量加大,围岩相似材料渗透系数呈非线性增长,稳定性逐渐降低,改变玻璃纤维的含量对其渗透系数影响不明显;注浆圈相似材料渗透系数值随炭渣含量增加近于线性增长,2.5 m水头下的试验值较1.35 m水头时更大;随着编织土工布叠加层数增加,初衬相似材料平均渗透系数呈快速减小并逐渐收敛的趋势,且单次渗透系数测试结果也趋于稳定;相同隧道排水量时,二衬外拱底处水压力远大于拱顶,逐步减小隧道排水量后,拱顶水压力值上升幅度大于拱底,调水阀接近闭合时,拱顶和拱底位置的水压力接近初始水压力.研制的相似材料工作性能稳定,并成功应用于工程渗流试验中.     

Gas seepage equation of deep mined coal seams and its application

In order to obtain a gas seepage law of deep mined coal seams, according to the properties of eoalbed methane seepage in in-situ stress and geothermal temperature fields, the gas seepage equation of deep mined coal seams with the Klinkenberg effect was obtained by confirming the coalbed methane permeability in in-situ stress and geothermal temperature fields. Aimed at the condition in which the coal seams have or do not have an outcrop and outlet on the ground, the application of the gas seepage equation of deep mined coal seams in in-situ stress and geothermal temperature fields on the gas pressure calculation of deep mined coal seams was investigated. The comparison between calculated and measured results indicates that the calculation method of gas pressure, based on the gas seepage equation of deep mined coal seams in in-situ stress and geothermal temperature fields can accurately be identical with the measured values and theoretically perfect the calculation method of gas pressure of deep mined coal seams.     

混凝土小砌块配筋砌体抗压性能的试验研究

通过22个混凝土小砌块灌芯砌体试件及其3个配筋砌体墙片的抗压试验，研究了作为配筋砌体结构基本性能的混凝土小砌块灌芯砌体抗压破坏特征和抗压强度，并在此基础上对配筋砌体的破坏特征和轴心抗压承载力进行了研究，分别提出了混凝土小砌块灌芯砌体抗压强度和配筋砌体墙片轴心抗压承载力计算公式，并进行了试验值和公式计算值的对比分析。