The collapsing load of the key stratum is obtained by adopting the plastical limit analysis method structure.Based on the collapsing load,the posotion of key stratum can be estimated approximatively.

• 并且采用结构塑性极限分析方法解析得出了关键层失稳时的极限荷载,依据此极限荷载可以近似判断出覆岩中关键层的位置。