煤矿采空区地表重力异常效应模拟研究

地下大规模采煤形成的空洞效应导致重力场发生变化,通过地面重力变化来反演采空区上方空洞特征及其演变对于煤矿安全生产和地面保护具有实际意义。长期以来,煤矿地下采空导致的地表重力异常效应因量级较小而被忽视。基于布格重力理论采用数值模拟方法得到采空区地表的重力异常分布特征,建立采空区深度、宽度、厚度及开采边界与地表重力异常分布的关系,并使用三阶紧致差分逼近算法得到采空区地表重力异常的一次差分曲线。通过加入随机误差模拟得到采空区地表重力异常值,采用不同拟合方法进行曲线平滑处理,依据其一次差分曲线的峰值来推断采空区的边界位置,为现有技术条件下利用重力变化反演煤矿采空区演变提供了可行性。

Simulation and study on ground gravity anomaly effect in goaf of coal mine

The goaf effect formed by the large-scale underground coal mining will change ground gravity field.Therefore,it is of practical significance to inverse the evolution and characteristics of variation of the hollow above the coal mine goaf by ground gravity survey for the safety of coal mine and ground protection.For a long time,due to its small magnitude,this kind of gravity anomaly effect caused by coal mine goaf is neglected.Based on the Bouguer gravity theory,the author uses numerical simulation method to obtain ground gravity anomaly distribution characteristics of the goaf in longwall face,and establish the corresponding relationship between depth,width,thickness,mining boundary of working face and the distribution of gravity anomalies,use third-order compact difference scheme to acquire its first derivative curve.Different kinds of fitting methods are adopted to smooth the distribution curve of the ground gravity anomaly in the goaf,which is simulated by adding random errors of different sizes.Also,according to the peak point of the first order difference curve,the boundary position of the goaf is deduced,which provides the feasibility of using the gravity method to inverse the change of coal mine goaf under the existing technical conditions.