受工艺和安全因素限制，我国露天煤矿端帮边坡角较缓，正常情况下仅为20°~35°，全国范围内数十亿吨的煤炭资源被端帮边坡压滞，随着内排及复垦工作的完成，这些压滞资源多数将无法回收。随着煤炭资源的日益减少和采矿技术的不断进步，煤炭开采逐渐由易采资源开采向深部资源和复杂难采资源开采过渡，露天矿端帮压煤及残煤回收逐步得到重视。工程实践表明，端帮采煤机开采技术是一种快速灵活、安全高效、经济环保的露天矿端帮压煤开采工艺，该技术的实质是在边坡下部煤层出露位置沿煤层施工一系列垂直于边坡走向的巷硐，开采全程无支护，通过各巷硐之间保留的支撑煤柱来支承上覆岩土体重量，致使“露采”和“巷采”2种开采方式的采动效应相互叠加、相互影响，最终形成了一个动态的空间形态多元化的复合系统，一旦支撑煤柱发生破坏，很可能诱发煤柱群的连锁失稳，从而导致端帮采场的大面积滑坡。因此，端帮采场安全的重要性不言而喻，而支撑煤柱和采场边坡的稳定性问题是保证端帮采场安全的关键。针对以上问题，以鄂尔多斯地区端帮采煤为背景，综合考虑“露采”与“巷采”2种采动效应叠加对边坡稳定的影响，构建了近水平条件下端帮采场岩土体变形破坏的3DEC数值分析模型，模拟研究了端帮压煤开采全过程采场覆岩的变形移动和应力分布规律。研究结果表明，根据岩土体移动变形特征，可以将采动边坡变形破坏过程划分为表生改造、结构改造、时效变形和最终失稳(稳定)4个阶段，结构改造阶段是边坡发生变形破坏的关键阶段，边坡上部区域是端帮采场边坡发生变形失稳的关键区域，可能的失稳模式为散体物料内部的圆弧滑动或沿软弱岩层的顺层滑动。通过研究，揭示了巷道群上覆岩体“扩大压力拱”的形成过程及其演化规律，提出了基于巷间煤柱合理留设的端帮采场覆岩稳定控制方法和永久隔离煤柱尺寸参数的确定方法，结合数值分析与工程实践，对理论公式的适用性进行了验证。

Due to the limitation of technology and safety factors,the end side slope angle of open pit coal mine in China is relatively low,which is only 20°-35° under normal circumstances,therefore,billions of tons of coal resources are trapped under the end side slopes,and after the completion of internal drainage and reclamation,most of these trapped resources will not be recovered.With the decrease of coal resources and the progress of mining technology,coal mining is gradually transferring from shallow coal resources to deep coal resources and complex and difficult coal resources,and more attention has been paid to the coal under end side slope and residual coal recovery in open pit coal mine.Engineering practice shows that the mining technology of end side shearer is a fast,flexible,safe,efficient,economical and environmentally friendly end side coal mining process in open pit coal mine.The essence of this technique is to construct a series of roadways along the coal seam at the exposed position of the coal seam at the lower part of the slope,and the roadways are perpendicular to the slope.There is no support in the whole mining process,and the weight of the overburden is supported by the supporting coal pillars retained between each roadway.As a result,the mining effects of “surface mining” and “roadway mining” are superimposed and influenced each other,and finally formed a dynamic complex system with diversified spatial forms.Once the supporting coal pillar is damaged,it is likely to induce the chain instability of the pillar group,which will lead to the large area landslide at the end side coal mining area.Therefore,it is of great importance to ensure the safety of the mining area,and the stability of supporting coal pillar.Slope is the key to ensure the safety of the mining area.To overcome the problems above,taking the end slope coal extraction of an open pit mine in Erdos area in China as the background,the influence of the superposition of “surface mining” and “roadway group mining”,which effects on slope stability,is investigated comprehensively.The 3DEC numerical analysis model for the deformation and failure of rock and soil mass in the coalface of end slope under near horizontal condition is constructed,the deformation movement and stress distribution characteristics of overlying rock in the whole process of coal mining are simulated.The research results show that according to the moving deformation characteristics of rock and soil mass,the deformation and failure process of mining slope can be divided into four stages:supergene transformation stage,structure modification stage,time dependent deformation stage and final instability (stability) stage.the structure modification stage is the critical stage of slope deformation and failure,and the upper part is the key area of deformation and instability in the process of end side coal mining,and the possible instability modes are the circular sliding inside the bulk material or the bedding sliding along the soft rock layer.Through the research,the formation process and evolution law of “distensible pressure arch” in the overlying strata of roadway groups are revealed,a method for the stability control of overburden rock of the coalface in end slope based on reasonable supporting coal pillars reservation is presented,and a method for determining the size parameters of permanent isolation pillar is established,finally,the applicability of the theoretical formula is verified by numerical analysis and engineering practice.

1 端帮采场覆岩移动破坏的数值模拟分析

   1.1 模型构建与分析方案

   1.2 采动边坡岩体变形移动特征

   1.3 采动边坡岩体应力分布特征

2 端帮采场覆岩移动破坏过程的阶段划分

   2.1 表生改造阶段

   2.2 结构改造阶段

   2.3 时效变形阶段

3 基于巷间煤柱合理留设的端帮采场覆岩稳定控制方法

   3.1 巷道群上覆岩体“扩大压力拱”的形成演化规律

   3.2 巷间煤柱的合理留设方法

4 结论