中文摘要：

煤层底板突水的实质是采动应力诱发底板岩体变形破坏,引发煤层底板突水.掌握底板岩层的破坏规律是承压水体上安全开采的首要问题.根据开采过程中回采工作面前后方支承压力分布规律,利用弹性力学理论,建立了煤层底板应力计算模型,分析了随着回采工作面推进煤层底板沿深度方向的最大主应力和最小主应力分布规律与底板剪切破坏形式.运用工程中常用的莫尔库伦准则,提出了煤层底板岩体的破坏判据.煤层底板的破坏易从回采工作面附近开始,向回采工作面后方采空区由浅而深发展,破断面呈抛物状弧面.应用直流电阻率法CT技术,在淮北孙瞳煤矿1028工作面风巷中煤层底板位置施工2个钻孔,在孔中埋置一定数量电极,形成孔间探测剖面,对煤层底板采动裂隙演化过程中的岩层电阻率响应特征和1028工作面底板破坏深度进行了动态综合探测.探测结果表明：1028工作面煤层底板在支承压力和底板承压水水压共同作用下,煤层底板的破坏范围在0～17m 在此范围内煤层底板岩层中垂向裂隙和层向裂隙发育明显,超过17m后底板岩层受采动影响较小,底板最大破坏深度约17m.通过直流电阻率法CT技术现场实测验证了理论分析是正确的和可行的.

英文摘要：

The paper is engaged in a study of effect of coal-mining on the bottom floor stress and its kinetic mechanism. As is well-known, mining stress is often likely to induce deformation and failure in the floor rock mass, which may in turn induce the bottom-floor water-inrush. Thus, there comes primary necessity for safe mining on the confined aquifer to grasp the deformation and failure regularity of the floor rock mass. According to the distribution regularity of abutment pressure in the front and rear of the mining surface, with the mining face gradually progressing, it is necessary to establish a coal floor stress calculation model based on the elasticity. In this paper, we have done thorough analysis on the stress distribution of the maximum and minimum principal stress along the depth bearing with a detailed discussion of the Shear failing forms of the coal floor as the mining face advances. Based on our study, the paper has worked out the cri- teria of coal floor rock mass failure in applying the Mobr-Coulomb cri- terion. Starting from the general failure rule of the mining floor from the front face and then progressing towards the rear face and from shallow to deep, we have worked out a parabolic camber shape of the failure face. Then, we have constructed two bores in the mining floor of No. 1028 working face in the Suntuan Coal Mine with a few elec- trodes set in the bores and the measurement sections between the bores. At the same time, the paper has also measured the failure depth and fissure dynamical evolution of No. 1028 working face in the Mine by means of DC resistivity method. The measured results show the floor of No. 1028 working face was split from 0 to 17 m by the abutment pressure associated with the floor confined water pres- sure while vertical fracture and horizontal fracture has also been well developed in the scope of floor failure. The maximum failure depth is 17 m deep because the effect of mining stress on the floor strata proves a little over 17 m. The field measurement with DC resistivi