矩形断面巷道的稳定性判别

A study on the stability of rectangular cross-section tunnel

为了研究矩形断面巷道的稳定性,采用强度折减法,运用有限元软件ADINA,对不同断面特征的模型进行仿真模拟分析。结果表明:矩形围岩切向应力分布与圆形断面类似,但最大切向应力并不在开挖面,而在围岩某一深度处;同面积而不同高跨比的矩形断面的安全系数很接近,当侧压力系数不同时总会有一个最大高跨比安全系数,该高跨比值在1附近;不同面积而相同高跨比,安全系数随着面积的增加越来越小。据此方法可确定矩形断面最佳高跨比。

In order to study the stability of rectangular cross-section tunnels,the strength reduction method and the finite element software ADINA were used to carry out simulation analysis for different sectional characteristics of the tunnels.The analysis results showed that the tangential stress distribution of the rectangular surrounding rock is similar to that of the circular one,but the maximum tangential stress is located at a certain depth in the surrounding rock rather than at the excavation face;for the rectangular sections of the same area but different depth-span ratios,the safety coefficients are very close,and there is always a largest safety coefficient of the depth-span ratio（about 1） when the lateral pressure coefficient is changed;for the rectangular sections of the same depth-span ratio but different areas,the safety coefficients decrease with the increase of the area.The optimum depth-span ratio can be determined according to this method.