The gradual settlement above old goaf threatens the safety of surface buildings.

采空区造成地层缓慢沉陷，严重威胁地表建筑物的安全。

youdao

The gradual settlement above old goaf threatens the safety of surface buildings.

采空区造成地层缓慢沉陷，严重威胁地表建筑物的安全。

youdao