中文摘要：

采用有限元强度折减法，求得煤层开采后底板岩体破坏滑移面，并给出底板塑性区贯通过程，得出其滑移线与理论形态相近，底板塑性滑移形状类似Prandtl型，并与滑移线理论计算结算进行了对比，两者误差在10％以内，说明了采用有限元法求解煤层底板破坏情况是可行的。并用于模拟上保护层开采过程中底板及下伏煤层卸压范围，为保护层工作面回采过程中瓦斯来源提供理论依据。说明有限元强度折减法可用于确定承压水体上煤层开采其底板所需的临界厚度和上保护层开采过程中的有效层间距。

英文摘要：

The plastic characteristics of the coal seam floor has been explored with the finite element strength reduction software of ANSYS; and its plastic area perforation process is given; and that the slip lines given by this methods are much close to theoretical solution; the plastic failure fields depth of the coal seam floor similar to Prandtl type; some parameters are compared with that by theoretical solution; the error is less than 10% so as to show that used the finite element intensity reduction method to solve floor damage situation is feasible. The scope of its plastic area can be used to reserve the safe thickness in water inrush from coal seam floor and the maximum effective spacing of liberated seam; then further utilizes in liberated seam to obtain its plastic area and slip lines.