It is pointed that the thick unconsolidated layers above roof have effect on post-buckling behaviors of key stratum, the equilibrium path of roof is unstable from breaking to final subsidence.

• 研究发现，顶板上覆厚松散沙层对关键层的后屈曲性态有影响；顶板从破断至极限下沉其平衡路径不稳定。