It gives the scientific voice way of horizontal crustal stress by gravity. 給出了重力所致水平地應力的科學表達方式。
Vertical stress makes rock stratum reforming voussoir beam, horizontal in-situ stress is the main source to cause the voussoir beam crushed. 豎直方向地應力使頂板岩層形成鉸接拱結構,水平地應力是拱鉸壓碎的主要力源。