石膏矿矿柱-护顶层支撑体系的流变力学模型分析

采用房柱法开采石膏矿体,将石膏矿柱简化为满足西原模型的黏弹塑性体流变模型,采空区上部留设的护顶层简化为弹性矩形薄板,建立了石膏矿矿柱-护顶层支撑体系的流变力学体模型。在此模型的基础上推导了矿柱支撑下采空区护顶层受流变作用的挠度微分方程,并根据其在不同阶段的边界条件采用伽辽金方法对该微分方程进行了求解。研究结果表明:当作用在矿柱上的应力σ大于极限摩阻力σ_s时,石膏矿柱的塑性流变大变形将随时间逐渐增大,极易导致石膏矿柱-护顶层支撑体系破裂直至坍塌;所建立的考虑矿柱流变特性的石膏矿采空区矿柱-护顶层支撑体系力学模型,可以对支撑体系的稳定时间进行预测。     

机械施工动荷载-采空区顶板失稳判据

针对机械施工荷载作用下采空区顶板失稳破坏具有突发性及受力过程复杂的特点,将机械施工荷载简化为移动简谐力,采用力学分析建立了机械施工荷载-采空区顶板力学模型。基于动力学理论,形成了机械施工荷载-采空区顶板的双尖点突变模型,由系统失稳的充分条件和必要条件,获得了机械施工荷载-采空区顶板失稳判据。基于能量原理,推导了机械施工荷载-采空区顶板总能量方程,根据系统临界失稳判据,构建了临界机械施工荷载计算模型。对建立的两种失稳判据分别进行实例验证,结果表明采用突变理论计算得到的理论状态与实测状态一致;采用能量原理计算得到的临界机械施工荷载理论值与实测值较吻合,平均误差为11. 01%。研究可为露天开采下机械施工荷载大小控制、采场结构参数设置、采空区失稳控制与治理等提供参考。     

基于颗粒离散元的矿柱群连锁失稳机理分析

矿矿柱群连锁失稳是破坏后果最为严重的采空区失稳模式。本文利用颗粒流离散元PFC2D研究了矿柱群连锁失稳的动态过程以及不同的矿柱安全系数、不同的诱发位置、不同的顶板刚度对矿柱群连锁失稳的影响。结果表明:(1)矿柱群的连锁失稳从诱发矿柱开始,失稳矿柱的应力传递到相邻未失稳的矿柱上造成相邻矿柱失稳,由此引发连锁效应;(2)矿柱的储备安全系数与载荷传递量的相对关系是决定矿柱群是否发生连锁失稳的关键;(3)矿柱群大规模失稳与诱发位置有关,诱发矿柱位于采空区的中心位置更容易形成大规模失稳,而位于采空区的边界位置,由于边界矿柱约束支撑作用则不容易诱发大规模失稳;(4)顶板的刚度显著地影响矿柱群的连锁失稳过程,刚度小的软弱顶板条件下,载荷传递从诱发位置向空区边界依次传递,失稳过程具有显著的"多米诺骨牌效应",而刚度大的坚硬顶板条件下,载荷传递与矿柱失稳不再表现出显著的"多米诺骨牌效应"。本文的研究成果可供开展相关工作借鉴。     

基于突变理论的小煤窑采空区失稳判据及应用

小煤窑采空区突发性垮塌灾害是榆神府矿区重大地质灾害问题之一。采用工程地质分析及数理推导的方法,分析了小煤窑采空区成灾条件及致灾机理,构建了顶板–残留煤柱岩石力学系统,推导了基于尖点突变模型的采空区系统失稳力学判据。以枣稍沟小煤窑为例进行分析,结果表明,该方法简便实用,计算结果可靠,为小煤窑采空区稳定性定量评价提供了一种新途径。      

多因素组合影响阶段矿柱上采顶板临界厚度研究

采用散体充填法的矿山,由于充填体无法直接暴露,阶段矿柱回采临界厚度的保留成为残矿回收的突出难题。基于传统弹性梁理论,结合实际情况,将阶段矿柱简化为均布载荷下两端固定的弹性梁力学模型,推导了其弹性应力解,揭示了 是阶段矿柱上采过程的第1破坏应力。理论分析表明：影响矿柱上采顶板临界厚度的主要因素为：散体载荷、回采跨度和岩体抗拉强度。利用FLAC3D完成了多因素组合影响阶段矿柱上采过程数值模拟正交试验,分析了单一影响因素与顶板临界厚度的关系,利用多元非线性回归的数学方法,建立了上采过程三因素组合影响下阶段矿柱临界厚度数学预测公式。最终,实现了散体介质下阶段矿柱上采临界厚度的预测。结合凤凰山铜矿-240 m阶段矿柱回采实际,表明了该预测公式的适用性。     

大冶铁矿大采空区动力稳定性研究

针对大冶铁矿尖林山1~#矿体大采空区(顶板水平暴露面积6434平方米,高45米)的特点,进行地质调查、振动测量、岩石力学试验、三维空间边界元分析及光弹性试验、动力模型试验。各项资料经综合研究后得出的结论是:该采空区基木稳定,在监测和限制爆破作业条件下,可以不放顶进行强采。现大冶铁矿尖林山1~#矿体已全部安全强采完毕,采终后大采空区空间尺寸为:长200米、宽78米、高73米,顶板水平最大暴露面积达9850平方米,该大采空区仍基本稳定。实践证明,本研究所作出的结论是正确的,它已取得显著的经济效益,它是岩石动力学应用于工程的一个典例,对于类似矿山的大采空区稳定性评价有借鉴意义。     

采空区块体稳定性的模糊随机可靠性研究

在介绍块体稳定可靠性分析各种方法的基础上,分析了采空区块体稳定状态的随机性和模糊性的特点,根据块体理论与模糊分析学中的模糊测度理论,提出了块体稳定性的模糊随机可靠性分析方法,建立了块体稳定性模糊概率测度计算公式,并将该方法应用于浙江遂昌金矿采空区顶板围岩块体稳定性分析的工程实践中,计算结果表明,块体稳定性较差,采空区残留矿柱回采前,需采取相应的安全措施。     

马达岭滑坡室内岩石力学试验研究

马达岭滑坡所在的自然边坡为一典型的缓倾斜横向斜坡,岩层近南北走向,呈软硬互层状结构。岩性以砂岩为主,坡体内存在大量软岩夹层和裂隙。斜坡下120m处发育有2层可采煤层,且煤层开采后留下大量采空区。斜坡的变形及稳定性主要受采空区顶板砂岩和坡脚煤岩的强度特性控制,本文以室内岩石力学试验为基础,系统研究了砂岩的基本力学属性及煤岩的抗剪强度特性,并分别分析了两种岩石的变形破坏特征。综合分析实验结果表明,砂岩的抗拉强度在坡体稳定性评价中起着控制性作用;煤岩的抗剪强度对斜坡稳定性影响最为直接;受层面控制,煤岩抗剪强度值较小,而其残余强度较峰值强度更是减小了60%;2种岩石的变形破坏特性受其风化程度不同,都存在较大差异。     

永川煤矿须六段砂岩力学性质与冲击倾向性实验研究

为了认识永川煤矿三叠纪上统须家河六段(T3xj6)地层砂岩的力学性质和冲击倾向性,以美国MTS815岩石力学测试系统作为动力设备,对砂岩力学性质和冲击倾向性进行了测试,并利用Origin7.5中的面积工具箱对冲击倾向性指标进行了计算,避免了曲线下面积计算不准确的缺点。实验研究结果表明:永川煤矿T3xj6砂岩具有杨氏模量较低、强度不高、变形曲线上的塑性变形表现不明显的力学特性;T3xj6砂岩具有冲击倾向性,但是冲击倾向性整体上较弱,局部有强烈冲击倾向性。研究结论为永川煤矿延深工程过三叠纪上统须家河六段(T3xj6)砂岩体发生动力灾害的治理工作提供了理论基础。     

金属矿山阶段嗣后充填胶结充填体矿柱力学模型分析

矿柱宽度和充填体自立高度是阶段嗣后充填顺利实施的重要影响因素。基于弹性力学平面应变基本假设,建立阶段嗣后胶结充填体矿柱力学模型并进行理论求解。以某铁矿为工程分析实例,采用控制变量法（CVM）研究矿柱不同宽度、高度条件下,水平应力和剪应力的变化规律。研究表明：矿房极限宽度和高度分别为19.8 m和103.2 m。胶结充填体矿柱水平应力随矿柱高度的增高而逐渐增大;剪应力在矿柱中心位置达到最大,且高度越大,剪应力值也越大。在胶结充填体矿柱与非胶结充填体接触侧剪应力趋于定值。矿柱宽度分别为15、18、20 m时,其剪应力分别为243.8、292.6、325.1 kPa。而产生剪应力的主要原因是非胶结充填体受水平应力作用在与胶结充填体矿柱接触面产生滑动摩擦力所致。     

Research on reasonable coal pillar width of roadway driven along goaf in deep mine

Driving roadway along a goaf is commonly adopted for mining face of thick seam in a deep mine. Determining a reasonable width of coal pillar is a key scientific problem for driving roadway along a goaf in a deep mine. The paper took a roadway driven along a goaf at Zhaolou coal mine which is a typical kilometer-deep mine in China as engineering background. Field monitoring, model test, and numerical experiment are conducted. Stress and displacement evolution mechanism are analyzed with different pillar widths. The test results show that with the increase of coal pillar width, the peak stress value at the coal pillar working slope and integrated coal beside the roadway increases firstly and then tends to be stable, its position is transferred to the side of the roadway, and the deformation of coal pillar decreases gradually during roadway excavation. The coal pillar deformation and roadway vertical displacement increased as the coal pillar width increases under high abutment pressure. In order to reduce the waste of non-renewable resources and meet the requirements of bearing capacity and stability of coal pillars, a method is proposed for setting a reasonable width of coal pillars and the specific width of coal pillars is designed and applied in engineering practices based on the above research. All the tests are significant in the study of driving roadway along a goaf in a deep mine.     

Study of roof stability of the end of working face in upward longwall top coal

Low recovery of longwall top coal caving (LTCC) remains one of the most difficult engineering problems in this mining method and impedes its application. The top coal left in the gob at face end accounts for a large portion of the total coal loss, and the instability of the leftover triangle coal at face end has long been a threat to the safety of miners and the mining equipment. In this paper, based on the engineering background of Ruilong mine, we explore the stability of the roof at the end of the face by using theoretical analysis, numerical simulation, and field measurement. Results reveal that in the inclined longwall top coal caving face, the immediate roof forms an “arch” structure, and the basic roof forms a “masonry beam” structure after the roof collapses; working resistance of the support calculated by the method of ultimate bearing capacity was adequate to meet the requirement of roof load; roof load of coal pillar was related to the length of key block and fracture position; and increasing the size of coal pillar could ensure the stability of both coal pillar and roof.     

下伏采空区对水库坝基稳定性和渗漏性的影响

结合延安某拟建水库的工程地质条件及采空区赋存状况,在分析房柱式采空区变形破坏形式及机理的基础上,分析了房柱式采空区对拟建水库坝基的稳定性及渗漏性的影响。稳定性分析认为:拟建场地采空区处于不稳定状态,在坝体荷载作用下,将引起采空区"活化",采空区对坝基及泄水涵洞等附属构筑物的稳定存在严重影响。渗漏分析认为,下伏采空区对拟建水库渗漏存在严重影响。在采空区未发生大面积拱冒、切冒破坏的前提下,采空区引起拟建水库的渗漏量为1 671.9 m3/d,约占水库年平均流域径流量的17.9%。当采空区发生大面积拱冒、切冒破坏条件下时,采空区产生的切冒破坏将引起坝基及两侧坝肩的绕流,在切冒陷落区与不扰动区接触带出现台阶,垂直坝基轴线方向形成上下游贯通裂缝或空洞,形成管涌破坏,导致坝体失稳。鉴于此,应对坝基采空区进行有效治理,以确保建设工程安全。      

Analysis on Roadside Support Method with Constant Resistance Yielding-Supporting Along the Goaf Under Hard Rocks

Under hard roof in mining, the roadside support body of gob-side entry retaining bears high pressure, and is easy to damage and fracture. It puts forward the new roadside support method with constant resistance yielding limit supporting. And through establishing mechanical model of the roadside support body in different stages of the sinking of the roof rotation, it discusses the force of supporting, deduces the parameters about the initial constant resistance and the lower limited deformation body in late stage. It is a mine 16209 working face track tunnel as the background and analysis the mechanism of the roadside under hard roof. In this mine the pressure height of the constant resistance body is 0.5 m, and the constant support resistance is 15 MPa. The width of the lower body is 1.8 m, and the compressive strength is 25 MPa. And by using reliability theories and engineering tests, research results show that the limited deformation body is stable; the support structure can guarantee the stability of the surrounding rock of roadway. Field tests show that the roadside support structure can ensure good effects roadway maintained along the goaf, the roadway can meet the needs of rocks safety.     

布筋尾砂胶结充填体顶板力学性状试验研究

胶结充填体顶板的稳定性是决定下向分层胶结充填回采断面尺寸的主要因素,结合武山铜矿工程实际,采用相似模拟与现场监测手段,研究了下向分层胶结充填法充填体顶板的破坏模式、变形特征、充填体内钢筋受力特征等。相似模拟试验结果表明,钢筋布置方式不影响顶板的最终破坏形式,竖直布置钢筋与水平布置钢筋相比,更有利于提高顶板整体稳定性。应变监测结果表明,充填体顶板应变状态十分复杂,与通常将下向胶结充填体顶板简化为梁的计算结果有较大不同,垂直方向上应变表现为拉伸应变,而沿分条和垂直分条方向应变均呈现拉、压交错变化。在竖直布置的8根钢筋上布置了24个钢筋测力计,得到了钢筋受力与开采时间的关系曲线,据此将钢筋受力划分为4个阶段,即起始受拉阶段、相对稳定阶段、拉压变化阶段、承载阶段,其中承载阶段钢筋首先承受最大压力,充填体暴露为顶板后,钢筋由受压状态变为受拉状态,并急剧上升到最大拉力,即表现出悬吊作用,并且,进路与分条连接处钢筋承受拉力最大。     

坚硬顶板强矿压动力灾害演化机理与超前区域防治技术

工作面上覆坚硬顶板往往不易垮落,破断后易形成动压灾害。以神东矿区布尔台煤矿为背景,针对典型坚硬顶板造成的强矿压动力灾害问题,采用数值模拟、理论分析的方法分析并揭示坚硬顶板弱化前后的应力演化特征及顶板破断机理,提出超前区域防治技术并应用于现场实践。结果表明:坚硬顶板破断演化特征分为3个阶段,即“长悬臂梁”阶段—“砌体梁滑落失稳”阶段—重新压实阶段,其中“长悬臂梁”阶段支架上方顶板应力显著增大至6.8 MPa,破断前支架上方顶板应力为破断后的2倍,其临界破断产生的应力释放是引起强矿压的根本原因,这也是弱化改造控制的主要阶段。基于坚硬顶板灾害发生机理,提出“广域大空间”超前区域防治技术,阐述了绿色、精准、广域的防治优势,以及钻孔轨迹控制、封孔质量控制、多孔联动效应的关键技术及治理评价体系。结合数值模拟进一步验证防治技术的可靠性,当“长悬臂梁”结构弱化后,其破断前支架上方顶板应力为4.6 MPa,降幅32.4%,顶板破断演化特征3个阶段演变为来压前阶段—“砌体梁滑落失稳”阶段—重新压实阶段,弱化后顶板各阶段支架上方顶板应力降幅达到32.4%~79.4%,表明预成裂隙弱面和降低坚硬层完整性能够有效改变顶板破断结构,显著降低来压强度。实践表明:压裂过程产生多次压降,降幅均达到3 MPa以上,探测裂缝发育长度达到30 m以上,压裂前后工作面周期来压步距降幅44.9%,支架来压载荷降幅18.1%,治理效果良好。研究结果可为类似矿区动力灾害治理提供借鉴。      

Study on Progressive Instability Characteristics of Coal-Rock Composite Structure with the Different Height Ratios

Geotechnical and Geological Engineering - To ensure the safety of coal mining, lots of coal pillars were reserved in the coal mine. The stability of coal pillar and roof composite structures...     

Creep Failure of Roof Stratum Above Mined-Out Area

By taking into account the rheological behavior of the rock mass, the creep failure of a roof stratum seated on pillars in mined-out area is analyzed through a newly developed visco-elastic model. The time-dependent deflection of the roof stratum is obtained by numerical inversion of Laplace transform. The study shows that when creep properties of both the pillars and roof stratum are considered, the expected deflection in the roof stratum increases with time. Consequently, the roof would fail when the critical tensile stress is reached as the result of the increased deflection. To demonstrate the present analytical procedure, the failure time of roof stratum of the Xingtai Gypsum Mine in China was estimated, and the results obtained agreed with the observation. The case study indicates that the analytic approach provides a new way to assess the potential impact of the time-dependence of the roof stratum deformation and is useful in predicting its stability above a mined-out area.     

Investigation of Instability and Blasting Caving Technology of Composite Support Structure in the Goaf of Gypsum Mine

According to the structure form of room and pillar goaf in gypsum mine, the mechanical model of pillar roof composite supporting structure was established in this research. Based on the cusp catastrophe theory and energy dissipation theory, the energy dissipation relationship of the support structure was analyzed, and a new instability criterion of the support system was derived by introducing the control parameters α and β. On this basis, the study of blasting caving was carried out. The influence of row spacing and hole depth on blasting caving was analyzed using ANSYS/LS DYNA software. The blasting influence range, stress wave attenuation and vibration velocity attenuation indices are obtained, and the blasting parameters such as the optimal distance and depth of blast holes between pillars and roof were optimized. Based on the results of theoretical analysis and numerical, combined with the engineering geological conditions of Dahan gypsum mine, the practical study of blasting caving was carried out. The caving scheme and caving sequence was determined, then the blasting caving effect was analyzed. The caving effect was found to be good, and the applicability of the theoretical model is verified.