中文摘要：

利用FLAC^3D软件建立双层空区数值计算模型,根据厚度折减理论分析开挖后空区的安全顶板厚度和应力、变形、塑性区的分布情况,得到：安全顶板厚度与空区跨度之间符合线性关系;当跨度较小时,上部空区处于压应力状态,下部空区处于拉应力状态,最大拉应力随跨度的增大而增大;当系统达到临界状态时,上、下空区顶板的竖直位移最大,上空区的大位移区域面积明显大于下空区的大位移区域面积;空区对整体位移存在一定影响,如水平方向对整体位移的影响范围大致为跨度的1.5倍,且两空区之间存在相互作用,在大位移区域两空区显示出相互接近的趋势;当跨度较小时,上部空区顶板主要发生剪切破坏,下部空区两侧帮发生拉剪破坏,随着跨度的增大,此范围破坏形式转变为冲切破坏,整体塑性区面积明显增大,下部空区顶板塑性区逐渐发展,并延伸至上空区。

英文摘要：

The numerical calculation model of double gob area was founded by FLAC^3D software. According to the thickness reduction theory, the safety roof thickness, stress, deformation, and plastic zones of gob area after excavation, analysis was made. The results show that the relationship between roof thickness and span of gob area is in accordance with the linear equation; when span of gob area is small, the area surrounding upper gob shows the compressive stress field, while the lower shows the tensile stress field, the maximum tensile stress increases with the increase of gob span; when the system reaches the critical state, the largest vertical displacement exhibits in the roof of gob, and the magnitude for the upper gob area is larger than that of lower gob area; excavation of rock mass has great impact on the displacement contour of whole system, the impact area is about 1.5 gob span in the horizontal direction; the two gob areas have the mutation effect to each other, which makes the big displacement area of each other move together; when span is small, the failure mode of upper gob consists mainly of shear failure, and rock mass in both side of lower gob area shows the compound failure mode consists of shear and tensile failure; with the increase of span, the failure mode changes to shear failure, and area of plastic zones becomes larger and larger; the plastic zones in the lower gob develop gradually to the upper gob.