覆岩运动演化是井下动力灾害孕育发生的根本原因,掌握具体地层条件下覆岩运动规律及其演化致灾机理对实现动力灾害防控具有重要意义。以 3301 工作面为工程背景,综合运用相似模拟、理论分析与现场实测相结合的方法,研究了表土层−基岩不同厚度组合变化下基岩、表土层及地表下沉盆地的整体破坏形态与联合运移演化规律,揭示了 2 类典型表土层−基岩组合条件下的覆岩结构运移演化规律及采动应力传递形成机制,推导获得了巨厚表土薄基岩条件下的支承压力定量表达式,并提出了高应力突变致灾宏观判别准则,现场工程实践验证了模型合理性。得到主要结论如下:① 煤层开采后软弱基岩呈现非对称“类梯形”破坏形态,巨厚松散表土层呈现“倾斜漏斗 形 ” 破 坏 形 态 , 表 土 层 运 移 演 化 具 有 响 应 速 度 快 、 运 移 范 围 广 、 下 沉 系 数 大 的 特 点 ;② 表土层−基岩双层介质在不同厚度组合条件下的运移演化规律具有较大差异,厚表土层薄基岩(I 型) 条件下,基岩自下而上发生塑性破裂,破断岩体块度小,难以形成稳定结构;厚表土层厚基岩 (Ⅱ型) 条件下,基岩由塑性破裂逐渐转化为块式破断,破断步距逐步增大,关键层效应逐渐突显,破断后形成结构的承载能力提高,能阻止上覆表土层的运移和沉降,地表下沉量出现一定程度的减小;③ 深厚表土薄基岩条件下,工作面前方大范围表土层向采空区发生运移,载荷集中作用在工作面上方基岩和超前煤体内,同时由于基岩软弱、破断岩块尺寸较小、无法形成规模悬顶的特点,限制了载荷向煤壁前方更远处传递,致使呈现应力峰值大、影响范围小、波动性大特点;④ 建立了考虑深厚表土大范围运移、基岩塑性破裂特征的支承压力估算模型,获得了支承压力计算方法,并以 3301 工作面具体参数为例,估算出其支承压力影响范围为 72 m,峰值为 44.2 MPa,应力峰值距煤壁 23 m,具有一定冲击风险;现场地表沉降特征与采动应力监测结果验证了理论分析与相似模拟结果的科学性。

The evolution of overburden movement is the basic reason for the occurrence of underground dynamic disasters. It is important to know the law of overburden movement under specific stratum conditions and the mechanism of itsevolution and disasters for the prevention and control of dynamic disasters. Based on 3301 panel as engineering background, this paper studies the overall failure morphology and combined migration evolution law of bedrock, surface soillayer and subsidence basin under different thickness combinations of topsoil-bedrock, and reveals the migration evolutionlaw of overburden structure under two typical topsoil-bedrock combinations, as well as the mechanism and mechanism ofmining stress transfer. The quantitative expression of bearing pressure under the condition of thick topsoil and thin bedrock is deduced, and the macro criterion for disasters caused by high stress mutation is presented. The rationality of themodel is verified by engineering. The main conclusions are as follows: ① After coal mining, the weak bedrock showsasymmetric “trapezoid-like” failure pattern, the huge thick and loose surface soil presents “inclined funnel” failure pattern,and the surface soil migration evolution has the characteristics of fast response, wide migration range and large subsidence factor; ② The movement and evolution rules of the surface-bedrock double-layer media under different thicknesscombinations are quite different. Under the condition of thick surface layer and thin bedrock (type I), the bedrock plasticfracture occurs from bottom to top, the fragmentation of rock mass is small, and it is difficult to form a stable structure; under the condition of thick topsoil thick bedrock (type II), the bedrock is gradually transformed from plastic fracture toblock fracture, the breaking step is gradually increasing, the key layer effect is gradually highlighted, the bearing capacityof the structure formed after breaking is increased, which can prevent the movement and subsidence of the overlying topsoil layer, and the subsidence of the surface is reduced to a certain extent; ③ Under the condition of deep and thick topsoiland thin bedrock, a large range of topsoil layer in front of the panel moves to the mined-out area, and the load concentrates on the bedrock above the panel and the coal body ahead. Due to the characteristics of weak bedrock, small size ofbroken rock blocks and the inability to form large-scale suspended roof, the load is restricted to be transferred fartherahead of the coal wall, resulting in the characteristics of large peak stress, small influence range and large fluctuation;④ An estimation model of support pressure considering large-scale movement of deep topsoil and plastic fracture of bedrock is established. The calculation method of support pressure is obtained. Taking 3301 panel body parameter as an example, the influence range of support pressure is estimated to be 72 m, the peak value is 44.2 MPa, and the peak stress is23 m from the coal wall, which has certain impact risk. The ground subsidence characteristics and mining stress monitoring results verify the scientific results of theoretical analysis and similar simulation.