中文摘要：

为研究缓倾斜中厚矿体采空区稳定性，在研究采空区失稳机理以及收集矿床资料、采矿进程及进行室内岩石力学实验的基础上，利用数值模拟软件FLAC对磨坊矿五号井2号矿体4号采场的开采活动进行了模拟．通过对采空区竖向应力分布，塑性区发展趋势以及剪应变增量的分析，得出了空区的稳定性程度及破坏发展趋势：（1）在空区顶板与地板中心处出现了拉应力的集中；（2）空区剪切破坏首先发生在角隅与矿柱的中下部，导致矿柱的失稳，然后再向空区边缘顶板上部发展，最终导致顶板整体塌陷；（3）一、二步开挖后空区处于稳定状态，最后一步开挖后，采空区失稳．

英文摘要：

In order to study the goaf stability of gentle dipped and medium thickness ore body, based on studying the mechanism mechanism of goafs, collecting the ore deposit data, mining process and the laboratory experiments of rock mechanics, the numerical simulation software FLAC is applied to simulate the mining work of 4th stope of the NO. 2 ore body in Mofang mine. According to the analysis of the goaf vertical stress distribution, the increasing tendency of plastic zones and the distribution of shear strain increment, the goal stability and failure tendency is concluded. The stability and tendency can be described as ： （ 1 ） Tensil stress concentration is induced at the middle of goaf roof and footwall; （2）The existing of shear failure at the corners and the bottom of pillars leading to the failure of pillars, and then spreading of the failure to the rim of goaf roof and the upper zones results in the total collapse of the roof, and （3）The goaf stays stable after excavationl and excavations, but goes to unstable after the last step of excavation.