When the effect of intermediate principal stress was considered in different degrees , the dimensions and shapes of surrounding rock mass is rather different , and this phenomenon will be more obvious with the increase of the difference of horizontal stress and vertical stress 當(dāng)不同程度地考慮中間主應(yīng)力的影響時,圍巖塑性區(qū)形狀和大小有較大不同,且隨水平應(yīng)力與垂直應(yīng)力差異性的增大,這種影響趨于明顯。