摘要
借鉴强度折减法计算边坡安全系数的思路,提出采空区安全顶板预测的厚度折减法.不断调整顶板厚度,直到其达到临界破坏状态,此时对应的顶板厚度即为安全顶板厚度.当顶板达到临界状态时,其位移将发生突变,计算不收敛,因此,将静力平衡方程组是否有解、计算是否收敛作为顶板破坏的标准.采用同时考虑拉伸和剪切破坏的Mohr-Coulomb准则,对某一采空区顶板安全厚度进行预测,并对采空区周围的应力和变形进行分析,结果表明:当采空区跨度分别为4,7,10,15,20,25 m时,顶板安全厚度为2.1,5.2,9.2,12.3,16.6,22.9 m;采空区跨度较小时,塑性区范围较小,顶板主要破坏形式为冲切破坏;随着跨度的增大,塑性区面积增加,破坏形式转变为垮落;当顶板发生破坏时,计算的不平衡力无法收敛,位移不断发展,位移最大值区域位于采空区正上部.
According to the idea of slope safety factor calculated by the method of strength reduction, the thickness reduction method was proposed to forecast the safety roof thickness of gob area. In the procedure of thickness reduc- tion method, the roof thickness was reduced gradually until it reached the critical failure state, which marked the minimum safety thickness. If roof reached the critical failure state, displacement of the grid in the roof would mutate, and the calculation would be divergent. So whether or not the static equilibrium equations was of solvability and the calculation was of convergence can be chosen as the standard of roof failure. The proposed method was ap- plied in the forecasting of one roof safety thickness in the gob area. In the calculation, the Mohr - Coulomb criterion was adopted, which can consider the tensile failure as well as shear failure of material. And the stress and deformation of the gob area were analyzed. The results show that the roof safety thickness are 2. 1, 5.2, 9. 2, 12. 3, 16. 6, 22.9 m, responding to the gob area span of 4, 7, 10, 15, 20, 25 m; area of plastic zones is small and failure mode is clicking for small span of gob area; with the increase of span, the area of plastic zones increases at the same time, while the failure mode transfers to caving; while the failure of roof takes place, the unbalance force of calculation can not convergent with the perpetual increase of displacement, and the maximum displacement zones are in the gob upper areas.
出处
《煤炭学报》
EI
CAS
CSCD
北大核心
2009年第1期53-57,共5页
Journal of China Coal Society
基金
国家自然科学基金资助项目(50774093)
高等学校博士学科点专项科研基金资助项目(20060533071)
中国博士后科学基金资助项目(20060400264)
中南大学博士后科学基金资助项目
关键词
安全顶板
厚度折减法
临界状态
破坏标准
safety roof
thickness reduction method
critical state
failure standard
