针对我国西部矿区浅埋近距离煤层房采煤柱下开采时易发生工作面压架、地表台阶塌陷以及矿震灾害的现象，采用物理模拟及数值模拟方法对下煤层工作面采动时上覆房采煤柱群的动态失稳过程及工作面压架机理开展研究。实测统计榆阳区部分矿井本煤层房式开采后，只有当房采煤柱的弹性核区比例大于31%时，房采煤柱才能处于长期稳定。下煤层采后的模拟结果表明:上覆房采煤柱的破坏形式及其失稳次序同其与下煤层工作面相对位置密切相关，房采煤柱依次从工作面开切眼位置、工作面位置、采空区中部位置发生破坏及失稳，且工作面开切眼和工作面位置处煤柱多发生顺向采空区的斜切破坏，而采空区中部煤柱则发生垂向压裂破坏。根据石圪台煤矿数值模拟结果显示，上部2-2煤层房采后煤柱支承应力峰值由原岩应力28 MPa增大至12 MPa，应力集中系数为428;当下部3-1煤层工作面采后，上覆2-2煤层房采煤柱的支承应力峰值增大至30 MPa，应力集中系数达1071;下煤层工作面开切眼侧与工作面正上方的房采煤柱呈现垂向不均匀承载特征以及受水平拉伸变形影响，是导致边界处房采煤柱易出现对角斜切破坏模式的主因。两侧边界煤柱失稳后，其顶板岩层瞬间发生整体拉剪破断从而引发矿震，顶板多层岩层以“整体运动”的形式急剧快速下沉并撞击底板，将采空区中部上方的房采煤柱压垮压塌，同时巨大的冲击力进而导致上下煤层间的岩层发生全厚切落，造成下煤层工作面发生切顶压架。实验发现从上覆房采煤柱群首个煤柱发生破坏至整体失稳运动并达到稳定，历时仅约为0.45 s，其中，上下煤层之间的岩层发生全厚切落历时仅约为0.05s。

In the western part of China,mine disasters such as support failure,surface stepped subsidence and mine earthquake,are prone to occur when lower coal seam is extracted which is closely beneath the coal pillars left after room-and-pillar mining with shallow overburden. In this paper,physical modelling and numerical simulation method were adopted to investigate the dynamic instability process of upper coal pillar group and the mechanism of support failure under the influence of lower coal seam mining. According to the measured statistics in some mines after coal mining of Yuyang District,only when the proportion of elastic core area of the coal pillars is greater than 31% can the room coal pillars keep long-term stability. The simulation result after mining lower coal seams shows that the failure form and instability sequence of the upper coal pillars have close relations with the positions relative to the lower coal seam working face. The damage and instability of room coal pillar occur in the positions of open-off cut,working face, and the middle of goaf successively. Furthermore,the coal pillars in the open-off cut and working face mostly show hor- izontal shear failure,while the coal pillars in the middle of the goaf show vertical fracturing damage. According to the numerical simulation results of Shigetai Coal Mine,the peak abutment pressure of coal pillar in upper 2-2 coal seam in- creases from in-situ stress 2. 8 MPa to 12 MPa after coal mining with the stress concentration factor at 4. 28. After the lower 3-1 coal seam working face mined,the peak abutment pressure of the retained pillar in upper 2-2 coal seam con- tinually increases to 30 MPa with the stress concentration factor up to 10. 71. The open-off cut side of the lower coal seam working face showed uneven horizontally bearing with the coal pillar directly above the lower coal seam working face and the influence of horizontal tensile deformation are the main reasons for the diagonal failure mode of the boundary coal pillars. After the instability of two sides coal pillars,the roof instantaneously occur overall shear break- age,causing mine earthquake,and multi-layered strata in the roof settled suddenly in the form of " rigid body motion" and hit against the floor,leading to the collapse of the room coal pillars in the middle of goaf. At the same time,the huge impact force further leads to the full cutting of the strata between the upper and lower coal seams,which results in the roof cutting and support failure in the lower coal seam working face. It was found in the experiment that there was only about 0. 45 seconds from the failure of the first coal pillar in the overlying coal pillar group to the overall unstable movement and the final stability,among them,the full cutting of the strata between the upper and lower coal seams on- ly took about 0. 05 seconds.