急倾斜多煤层开采地表沉陷分区与围岩破坏机理——以木城涧煤矿大台井为例

为了研究急倾斜多煤层开采条件下地表及围岩移动变形特点,以木城涧煤矿大台井急倾斜多煤层开采为研究对象,进行了相似材料模拟研究.揭示了地表移动变形规律和围岩垮落、破坏机理,得出了不同区域移动变形的大小及主要特点,并与实地观测数据进行了对比分析.结果表明:该条件下开采,地表沉陷盆地可分为露头塌陷区、整体沉陷区、渐变沉陷区和轻微沉陷区,浅部开采形成的地表分区格局对整个采动影响区的地表移动变形起到了控制作用,浅部开采覆岩破坏以陷落和张裂为主要特征,深部开采以离层带裂隙顺层通达地表和台阶错落下沉为主要特征.     

挂帮矿开采对露天矿边坡稳定性的影响

为了避免挂帮矿开采过程中露天矿最终边坡失稳现象的发生,以一个大型铁矿区的露天矿为研究背景,构建了露天矿挂帮矿开采边坡稳定性数值计算模型.通过数值计算分析,得出受挂帮矿开采扰动影响,露天矿边坡从采空区所在台阶依次向上发生滑移现象,最大水平移动区域位于挂帮矿开采采空区的上一台阶,逐步向边坡内部和上部台阶减缓,总体移动趋势是由边坡上部台阶和内部向露天矿边坡移动;采空区上部台阶位移规律相似,即随着开采的进行,采空区上部台阶由下至上依次发生位移;受开采扰动影响,采空区顶部形成了不同方向的应力集中现象,这可能会使得边坡内部的覆岩向露天矿采场发生滑移,从而影响边坡的稳定性.     

PTS采动沉陷模型研究

在厚积冲层条件下，采动沉陷盆地基岩上表面形成的下沉空间可以认为是采空区向上传播的结果，也是地表得以下沉的必要条件，由于冲积层结构松散，抗弯能力低，与基岩相比，属于软弱层，而基岩对整个上覆岩层的移动变形及破坏过程起着控制作用，因此，基岩可 地表沉陷的控制层，本文采用不同的思路和方法来建立厚冲积层条件下的采动沉陷的控制层。本文采用不同的思路和方法来建立厚冲积层条件下的采动沉陷模型，并推导出了计算公式最     

采动区铁路桥沉陷加固治理

根据煤矿采动区地表沉陷变形规律，建立合理的数值计算模型，研究地下开采引起的地表移动变形对原设计的桥体结构和地基产生的附加内力和附加变形规律，提出了有效地加固治理方案，确保在采动引起的地表不均匀、大幅度沉陷过程中桥体的安全可靠和正常使用。     

采空区地表移动监测与规律分析

本文阐述了在矿井采空区首采工作面在采动过程中,通过地表移动变形监测、数据处理,分析出地表变形观测点的下沉与水平变形规律,并求得地表移动的部分参数,可为后续的矿井开采过程提供安全可靠的依据。     

PTS采动沉陷模型研究

在厚冲积层条件下，采动沉陷盆地中基岩上表面形成的下沉空间可以认为是采空区向上传播的结果，也是地表得以下沉的必要条件。由于冲积层结构松散，抗弯能力低。抗剪强度也小，与基岩相比，属于软弱层，而基岩对整个上覆岩层的移动变形及破坏过程起着控制作用，因此，基岩可认为是地表沉陷的控制层。本文采用不同的思路和方法来建立厚冲积层条件下的采动沉陷模型，并推导出了计算公式最后用实例进行了验证。     

不同原岩应力下厚度对急倾斜矿体开采岩移规律的影响

为研究不同原岩应力环境下厚度对急倾斜矿体开采岩体移动规律的影响,基于三维离散元软件3DEC,对比分析了自重应力和构造应力(σ_h/σ_ν=1.5)条件下,五种不同矿体厚度开采引起的地表与围岩移动变形规律.结果表明:在两种不同原岩应力环境下,围岩与地表移动量及采动影响范围均随矿体厚度的增大呈非线性增加,但是二者在地表沉陷盆地形态及变形速率、采空区围岩移动特征、变形影响范围等方面存在较大差异.原岩应力场中作为特征量的最大主压应力的方向对岩体移动行为的影响是引起这种差异的根本原因.     

“三软”特厚煤层开采地表沉陷规律研究

洛阳常村煤矿开采煤层为"三软"特厚煤层,井田范围内村庄较多.为了合理回采村庄下煤柱、提高资源采出率,需要掌握该地质条件下的地表移动变形规律及参数.在该矿"三软"特厚煤层工作面建立了地表移动观测站,对地表沉陷进行现场观测,获得了大量的地表沉陷观测资料.通过对实测资料的分析,得出常村煤矿"三软"特厚煤层开采地表沉陷规律及其参数.研究结果表明:与一般地质采矿条件相比,"三软"特厚煤层放顶煤开采具有地表移动角量参数偏小、影响范围大、下沉系数大等特点,地表沉陷呈现塌陷坑及台阶裂缝形态.     

露天煤矿端帮残煤开采及边坡暴露时间分析

为了提高露天开采的煤炭资源回收率，掌控露天煤矿端帮残煤开采工程安排，提出了水平和近水平大型露天煤矿汽车运输内排条件下，露天煤矿端帮露井联采、端帮陡帮开采、减少露天煤矿端帮边坡暴露时间的措施．结果表明：采掘工作帮帮坡角越大、内排土场工作帮帮坡角越大、工作线推进强度越大、内排土场下部水平排土台阶高度越大、采场坑底宽度越小露天煤矿端帮边坡的暴露时间越短；当露天煤矿端帮实行陡帮开采时，汽车运输内排通路可设在采场中部回填搭建。     

采动引起的地表变形对框剪结构的影响

利用通用有限元计算软件ANSYS进行分析,采用固定支座模型,人为地给柱脚支座以支座沉陷,以此模拟不均匀沉降.对框剪结构在采动引起的3种不同地表变形作用下进行了计算,得出了结构在不同地表变形作用下,上部结构内力的变化及分布规律.为研究采动影响下地表变形对建筑物的影响提供参考.     

拉斗铲作业实体高台阶安全稳定性研究

采用极限平衡法和FLAC3D数值模拟法对不同高度、坡面角、载荷情况下,以及岩石台阶下留不同宽度的煤柱等状态下,拉斗铲作业实体高台阶的安全稳定性进行了系统地研究.用赤平极射投影法确定黑岱沟露天煤矿拉斗铲作业实体高台阶的破坏形式为楔形体单面滑动和楔形体双面滑动.研究成果经现场实际应用证明,黑岱沟露天煤矿拉斗铲作业实体高台阶采用高38m、坡面角65°、留4m煤柱的参数是安全稳定和合理可行的.     

深部条带开采下沉系数与采厚关系的数值模拟

以峰峰万年矿的地质采矿条件为原型,利用FLAC3D数值模拟软件,建立了深部大采宽条带开采数值模拟模型,对开采厚度与下沉系数的关系进行了研究.结果表明：在采深和采出率等条件相同的情况下,地表下沉值和水平移动值均随采厚的增加而增大,而下沉系数随采厚的增加以非线性关系逐渐减少.下沉系数与开采厚度关系的确立,对深部大采宽条带开采地表移动变形预计及优化设计具有指导作用.     

深部条带开采下沉系数与采厚关系的数值模拟

以峰峰万年矿的地质采矿条件为原型,利用FLAC3D数值模拟软件,建立了深部大采宽条带开采数值模拟模型,对开采厚度与下沉系数的关系进行了研究.结果表明:在采深和采出率等条件相同的情况下,地表下沉值和水平移动值均随采厚的增加而增大,而下沉系数随采厚的增加以非线性关系逐渐减少.下沉系数与开采厚度关系的确立,对深部大采宽条带开采地表移动变形预计及优化设计具有指导作用.     

含水松散层固结对地表沉陷影响的数值分析

为了研究含水松散层固结对地表沉陷的影响,基于固结沉降量对预计参数确定的重要性,分析了影响含水层固结的因素,包括渗透系数、松散层厚度、采动程度和采煤方法.在分析现场实测资料的基础上,采用FLAC3D流-固耦合计算的方法,对覆岩内部位移场和渗流场进行了分析,研究了含水层固结压缩对地表沉降的影响.结果表明不考虑冲积层含水时,地面最大沉陷值为1220mm,考虑冲积层含水时,最大沉陷值为1306mm,下沉量增加86mm.地面沉陷盆地的外缘,沉陷量显著增加,增加量为160mm,最大沉降增加量为7%;走向方向和倾向方向松散层含水条件下均比不含水条件下水平移动量大,走向方向最大相差122 mm,倾向最大相差105 mm.     

FLAC3D在张集煤矿开采沉陷预测中的应用分析

利用FLAC~(3D)数值分析软件,分析了高潜水的张集煤矿巨厚松散层下12171工作面重复开采对上部17278工作面移动变形区的走向位移、垂直应力分布和塑性破坏区的影响。分析结果表明:数值模拟结果与实测数据基本相符;多煤层重复采动地表下沉具有特殊性,下沉量相比于初次采动是逐渐增大的,随着重复采动次数的增加,下沉量逐渐趋于稳定;同时随着工作面累计推进距离的增加,地面沉陷范围逐渐增加,并形成塌陷盆地;两工作面顶板围岩以剪切破坏为主,局部发生拉伸破坏。     

厚松散层下煤层开采地表沉陷模拟研究

以国内某大型煤矿为原型,采用FLAC3D有限差分软件对厚松散层下,内部煤矿开采过程中地表沉陷进行数值模拟,并对模拟结果进行了分析和探讨.研究表明：随着煤炭资源的采出,地表沉陷不断增大,并且相比于一般条件,厚松散层下煤炭开采所产生的地表沉陷影响范围变大.     

Probabilistic assessment of rock slopes stability using the response surface approach——A case study

This paper examines the stability condition of a jointed rock slope in the south western region of Saudi Arabia using deterministic and probabilistic approaches, under both dry and wet conditions. The study area is characterized by complex geology in rugged terrains. The stability analysis is carried out using the code FLAC3 D to generate a 3-dimensional, ubiquitous joint model, to determine the influence of the dominant, unfavourable discontinuity orientation with respect to the slope face. The deterministic analysis is first implemented using the mean values of the selected random variables, namely the dip,dip direction and friction angle of the dominant discontinuity set, and the stability condition is assessed with a factor of safety based on the classical frictional joint constitutive model. A Box-Behnken design(BBD) approach is then adopted to create the surface response function as a second order polynomial for the factor of safety. To do so, fifteen FLAC3 D models are generated in accordance with the BBD.Based on this, 10,000 simulations of different slope realizations are carried out using Monte-Carlo simulation technique, and the probability of unsatisfactory of performance of the rock slope is assessed. It is shown that the probabilistic approach provides more insight and confidence in the stability condition of the rock slope, both under dry and steady state heavy rainfall conditions. A discussion is presented on the significance of accepting lower safety factors when heavy rainfall conditions are encountered.     

Improved slope safety analysis by new Druker-Prager type criterion

Based on Mohr-Coulomb (M-C) criterion, the parameters of Druker-Prager (D-P) criterion for geomaterial were determined under non-associated flow rule, and thus a new D-P type criterion was presented. Two assumptions were employed during the derivation: 1) principal strains by M-C model and D-P model are equal, and 2) the material is under plane strain condition. Based on the analysis of the surface on π plane, it is found that the proposed D-P type criterion is better than the D-P criterion with M-C circumscribed circle or M-C inscribed circle, and is applicable for stress Lode angle less than zero. By comparing the predicted results with the test data of sand under plane strain condition and other D-P criteria, the proposed criterion is verified and agrees well with the test data, which is further proved to be better than other D-P type criteria in certain range of Lode angle. The criterion was compiled into a finite difference package FLAC3D by user-subroutine, and was used to analyze the stability of a slope by strength reduction method. The predicted slope safety factor from the proposed criterion agrees well with that by Spencer method, and it is more accurate than that from classic D-P criteria.     

广西洞巴水电站溢洪道边坡稳定性分析

洞巴水电站溢洪道边坡为粉砂岩与页岩互层,地质构造发育,在开挖及泄洪雨雾情况下的稳定性,对水电站施工及运行非常重要.采用赤平极射投影、理正岩土和FLAC3D等方法对该边坡稳定性进行分析对比,边坡在开挖过程中处于整体稳定状态,但可能局部失稳,得出的结论与实际情况吻合,为溢洪道的设计和施工提供了有益的参考.     

Effect of longwall-induced subsurface deformations on shale gas well casing stability under deep covers

This paper presents the results of a 2017 study conducted by the National Institute for Occupational Safety and Health(NIOSH), Pittsburgh Mining Research Division(PMRD), to evaluate the effects of longwall-induced subsurface deformations within a longwall abutment pillar under deep cover. The 2017 study was conducted in a southwestern Pennsylvania coal mine, which extracts 457 m-wide longwall panels under 361 m of cover. One 198 m-deep, in-place inclinometer monitoring well was drilled and installed over a 45 m by 84 m center abutment pillar. In addition to the monitoring well, surface subsidence measurements and underground coal pillar pressure measurements were conducted as the 457 m-wide longwall panel on the south side of the abutment pillar was being mined. Prior to the first longwall excavation, a number of simulations using FLAC3D~(TM) were conducted to estimate surface subsidence, increases in underground coal pillar pressure, and subsurface horizontal displacements in the monitoring well. Comparisons of the pre-mining FLAC3D simulation results and the surface, subsurface,and underground instrumentation results show that the measured in-place inclinometer casing deformations are in reasonable agreement with those predicted by the 3D finite difference models. The measured surface subsidence and pillar pressure are in excellent agreement with those predicted by the 3D models.Results from this 2017 research clearly indicate that, under deep cover, the measured horizontal displacements within the abutment pillar are approximately one order of magnitude smaller than those measured in a 2014 study under medium cover.