高应力区域煤层巷道耦合支护数值模拟试验研究

为了研究耦合支护控制巷道变形的效果,根据耦合支护原理,使用FLAC3D有限差分数值模拟软件对某矿11010工作面回风巷在不同支护参数下巷道的顶板、底板、左帮和右帮深部基点位移与围岩最大位移进行了研究.结果表明,当支护体与围岩以及支护体之间在强度、刚度、结构满足耦合支护时,巷道深部基点位移与围岩最大位移均较小,且巷道处于稳定状态所需时间较短.通过工程实例进一步说明了耦合支护能有效地控制巷道围岩变形,维护巷道稳定.     

煤层干式钻孔粉尘质量浓度分布规律的数值模拟

干式钻孔过程中,风力排渣系统将钻屑沿钻孔环状狭缝高速排出,会产生高浓度粉尘.为有效地控制煤层干式钻孔粉尘污染,探寻影响粉尘分布的主要因素,确定出粉尘质量浓度较低的钻孔工艺参数配置,运用SolidWorks联合DesignModeler建模、Mesh划分网格、Fluent解算、CFD-Post后处理等手段,对不同边界条件下煤层干式钻孔粉尘质量浓度分布进行数值模拟,并与现场实测数据对比分析,两者基本吻合.研究结果表明:压风自环状狭缝喷出后速度急剧衰减,整体呈锥体分布,大颗粒钻屑喷出孔口后就地沉降,细小颗粒悬浮在空气中并随风流继续扩散;钻场内粉尘质量浓度沿程先急剧上升至一个最大值,后快速下降,再逐步缓慢降低;水平方向上,机道中央粉尘质量浓度最高、巷道中央次之、人行道中央最低;竖直方向上,粉尘质量浓度呈现出中间高、上下两侧低的分布规律;钻场风速、钻杆转速、供气压力、钻杆型式及钻孔类型是影响粉尘分布的5个主要因素;当钻场风速为0.5 m/s、钻杆转速为2 r/s、供气压力为0.8 MPa时,采用外平钻杆钻进斜平行预抽钻孔,可取得良好的减尘效果.研究成果可有效地指导现场钻孔作业和防尘装置研发.     

顺煤层钻孔聚氨酯长距离快速封孔测压技术

顺煤层长钻孔采用聚氨酯封孔必须解决聚氨酯初始发泡时间、注入方式、封堵方式等关键工艺问题.通过在南庄12号煤层的现场试验,采用35 m封孔段长度、1∶1.25的聚氨酯黑白料配比、两堵一注封孔方式,测得煤层瓦斯压力为0.39～0.74 MPa,成功解决了顺煤层钻孔测不出煤层瓦斯压力的问题,其最大测值比瓦斯压力反演值低19.57％,说明聚氨酯封孔本煤层测压仍存在技术难度大、测值偏低等问题,但研究结果对于同类条件下瓦斯压力的准确测定具有指导意义.     

“三软”煤层回采巷道钻孔卸压参数研究

回采巷道围岩控制一直是"三软"煤层开采高产高效的制约因素之一.根据永华一矿的地质条件,针对传统支护方式无法解决"三软"煤层回采巷道支护的难题,采用理论分析、现场试验的方法,提出了钻孔卸压与U型钢支架耦合支护技术.即通过在巷道U型钢支架之间打卸压钻孔,为巷道围岩变形留设变形空间,降低围岩应力,达到巷道稳定的目的.试验表明,U型钢支架耦合支护和钻孔卸压能够有效地控制巷道围岩变形,支护效果良好,为"三软"煤层回采巷道围岩控制提供了实践和理论依据.     

基于定向声波扫描的钻孔围岩结构探测方法

在大型水利水电、能源交通等基础设施的建设中,查明岩体结构中存在的不良地质特征是保证工程顺利建设的重要基础,而常规物探方法很难探测到钻孔围岩结构的精细特征以及异常区域的范围和走向,为此,本文在实验室岩样缺陷检测方法的基础上,提出了一种基于定向声波扫描的钻孔围岩结构探测方法,该方法为了适用于钻孔围岩结构特征探测,采用了定向声波探头、旋转部件以及定位装置相结合的技术方法来实现。首先,根据扫描探测数据建立了环形扫描矩阵,提出了构建环形扫描图的数据处理方法;随后,构建了声波数据和环形扫描矩阵的映射关系,将对应的声波处理数据按照映射关系进行对应匹配,形成了钻孔围岩结构断面图,在叠加深度信息之后实现了钻孔围岩结构的立体图重建;最后,针对钻孔围岩缺陷区域的岩石声速及缺陷位置参数难确定问题,通过利用不同频率声波在岩石中传递的相位特征关系,构建了声速维和距离维二维扫描向量,采用数值分析方法来求解岩石的声速以及异常区域的位置,实现了钻孔围岩的结构特征立体呈现和参数提取,并将该方法应用到了实际工程中,验证了方法的可行性和准确性。     

高瓦斯煤层千米定向钻孔煤与瓦斯共采机理

结合最新引进的德国DDR-1200型千米定向钻机,提出在工作面顶板裂隙带内打千米定向钻孔抽采瓦斯的新方法,构建千米定向钻孔煤与瓦斯共采体系.结果表明,工作面上覆岩层存在大量横向间隙和竖向裂隙,裂隙带高度为34m左右,最大离层裂隙发生在主关键层下方,距离工作面顶板22m左右,最大离层量240mm,形成瓦斯富集区域;工作面倾向方向,回采巷道向采空区方向0～60m范围内裂隙最发育,并能长期稳定存在.据此在14301工作面进行工业性试验,试验结果表明,钻孔布置在14301工作面上方顶板22m左右,倾向方向距运输巷15m处,抽采浓度达70%以上,抽采时间在120d以上,取得最佳瓦斯抽采效果,实现煤与瓦斯共采.     

直墙拱形巷道围岩应力场分析

为得出直墙拱形巷道围岩应力分布规律,应用复变函数弹性理论推导了直墙拱形巷道围岩应力分布的解析表达式。对直墙拱形巷道边界的围岩应力和巷道水平线方向的围岩应力分布规律进行分析,并考虑直墙拱形巷道断面高宽比和侧压系数对其影响规律。研究表明：在不同巷道断面高宽比、侧压系数下,直墙拱形巷道围岩应力集中区域主要集中在直墙底部底角处、拱形顶板中点附近和底板中部3个位置。不同巷道断面高宽比下,直墙拱形巷道沿水平线的应力分布规律基本相同。侧压系数大于1时,采用巷道断面高宽比小于1较有利于巷道稳定;侧压系数小于等于1时,采用巷道断面高宽比大于1较有利于巷道稳定。     

Analysis of stability of support and surrounding rock in mining top coal of inclined coal seam

The study analyzes the characteristics of roof movement in mining top coal of inclined coal seam, and establishes the mechanical model of support and surrounding-rock stability in inclined coal seam. Besides, this study carries out the numerical calculation and field observation of roof movement and support stability, and provides the critical control measures. The results show that the fracture firstly appears in middle-upper roof and extends upwards in top coal caving in inclined coal seam; regular and irregular caving zones appear in middle-upper stress concentration region, and the asymmetric caving arch is finally formed. Support load of middle-upper working face is larger than that of the middle-lower face; dynamic load coefficient of upper support is large, and the load on the front of support is larger than that on the rear of it, which leads to poor support stability. Stability of support and surrounding-rock system depends mainly on upper-support stability.     

Test studies of gas flow in rock and coal surrounding a mined coal seam

An analysis of the variation rule of abutment pressure at the mining working face in a single coal seam and the mechanical behavior of surrounding rock during stoping is presented. Consideration of the elastic and plastic deformation zones that develop during the mining process allowed the determination of a relationship between horizontal stress and vertical stress. Based on this, a confined pressure unloading test was conducted by the use of the “gas-containing coal thermo-fluid-solid coupling 3-axis servo seepage” experimental apparatus. Thus, gas flow patterns in the elastic and plastic zones were derived from an experimental point of view. Darcy’s law and the Klinkenberg effect were used to derive a gas flow equation for the elastic and plastic stress fields. The study of gas flow phenomena at the working face during coal mining is of great importance for the study of gas migration and enrichment patterns.     

松软煤层穿层钻孔水力压裂实验研究

分析了煤层水力压裂增透的原理,设计了两个穿层钻孔(一个压裂对象为构造软煤,另外一个为软煤的坚硬顶板)的压裂方案,在淮北矿业(集团)有限责任公司临焕煤矿进行了现场试验,采用压裂后钻孔瓦斯抽采浓度与流量等指标考察压裂效果.试验表明,水力压裂对松软煤层效果甚微.针对这一问题,提出了对松软煤层的坚硬顶板进行压裂以达到对该煤层卸压增透的目的,现场结果表明松软煤层顶板压裂能大幅增加松软煤层的渗透率,增强瓦斯抽放的效果.     

Experimental and measured research on three-dimensional deformation law of gas drainage borehole in coal seam

Using self-researched gas drainage borehole stability dynamic monitoring device, three-dimensional deformation characteristics of borehole under steady vertical load were researched experimentally and systematically. This research indicated that under the action of steady loading, the mechanical deformation path of the simulated gas drainage borehole is gradually complicated, and the decay of the borehole circumferential strain is an important characterization of the prediction and early warning of borehole instability and collapse. The horizontal position of borehole occurs compressive strain, and the vertical of which occurs tensile strain under the action of vertical stress. At the initial stage of loading, the vertical strain is more sensitive than that in the horizontal direction. After a certain period of time, the horizontal strain is gradually higher than the vertical one, and the intersection of the borehole horizontal diameter and the hole wall is the stress concentration point. With the increase of the depth of hole, the strain shows a gradual decay trend as a whole, and the vertical strain decays more observably, but there is no absolute position correlation between the amount of strain decay and the increase in borehole depth,and the area within 1.5 times the orifice size is the borehole stress concentration zone.     

Numerical simulation and damage analysis of fissure field evolution law in a single coal seam mining

Based on the different deformation and failure laws of coal and rock materials under tensile or compressive loads, the damage variable was defined to divide three phases from the damage and rupture point of view in order to reveal the fissured field evolution characteristics and spatial distribution of coal and rock in the single coal seam mining with low permeability and rich methane. According to the corresponding damage constitutive equations, the secondary development of the finite element program was completed. The fissures field evolution law of a coal mine with single coal seam mining was calculated and analyzed by this new program and the distribution areas and failure degree of the surrounding coal and rock structures with damage, fissure or rupture are given on the condition of mining. This paper provides a scientific basis for quantitative research and evaluation of the safe simultaneous production of coal and gas.     

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．     

煤层断层构造演化应力场分布特征数值模拟研究

采用有限元数值模拟软件ADINA,模拟了一次构造作用下煤层断层构造的形成过程以及煤层断层形成后受现代构造应力场作用下煤层的破坏情况及地应力的分布规律.模拟结果表明,一次构造作用下煤层断层构造的形成过程中,在接近断层面的下盘煤层底部和接近断层面的上盘顶部,煤体容易遭到破坏;断层构造形成后在不同的铅直应力和水平应力组合情况下,正逆断层的下盘断层面附近区域均存在应力集中现象,逆断层的应力场方向主要由最大应力的方向决定,而正断层仅在水平应力与铅直应力比较接近时,应力场方向主要由铅直应力决定.     

Similarity simulation of bolt support in a coal roadway in a tectonic stress field

In order to study the mechanism of bolt support and the behavior of strata in a coal roadway under tectonic stress,deformation and destruction of a roof,floor and sides were studied using an experiment in similarity simulation.We also studied the mechanism and types of bolt support functions in the coal roadway.The results show that with an increase in horizontal tectonic stress,the strata in the roof and floor of the roadway gradually separate and become shear failure areas.Coal in side walls moves,but its integrity remains intact.Side bolts are mainly affected by tension and roof bolts by the effect of shear.     

A study of fire propagation in coal seam with numerical simulation of heat transfer and chemical reaction rate in mining field

Spontaneous combustion of coal is a problem that affects the mining operation and generates environmental, economic, social and geotechnical impacts. This phenomenon has been divided into two processes: ignition and propagation. Fire propagation develops in coal seams because of a set of factors such as direction and wind speed, fracturing and temperature. In this work, heat transfer and chemical kinetics are studied from conservation equations of energy and species, respectively, using the software COMSOL Multiphysics to simulate the propagation of fires in coal seams. Two possible scenarios were analyzed that usually occur in the walls of the coal seams, such as fire focus and fire complete screens. It was found that the propagation kinetics of the fire changes depending on the temperature, the fracturing of rock mass and the area of fire influence. For temperature values lower than 300 °C, there is consumption around 250 cm³/h, values around 700 °C, the consumption is 1500 cm³/h, and for fires of 1200 °C have values of 3000 cm³/h. Depending on the speed of propagation can vary from 4 to 17 cm/day, considering on the level and fracturing of the final wall of the open pit.