垂直节理影响的黄土隧道洞口段稳定性分析

通过模拟节理发育位置和数量的不同,在考虑隧道洞口段上覆土层厚度及洞周土体含水量变化的条件下,对黄土隧道洞口稳定性进行了计算分析。计算结果表明:在隧道洞口宽度范围之内,节理在拱顶中部时对拱顶沉降的影响较小,节理位置越偏离中部,拱顶沉降越大。节理位置位于隧道洞口段某侧时,节理发育一侧土体的相对剪应力水平和屈服区域面积均大于另一侧,说明节理对隧道洞口段有不利影响。当节理在洞顶两侧同时出现时,土体塑性区沿着节理面迅速发展,拱顶中部土体被节理充分切割,形成危险滑体。

Stability Analysis of Loess Tunnel Entrance Section Considering the Impact of Vertical Joints

This paper mainly focuses on the stability analysis of the loess tunnel entrance section by numerical analysis method with the factor including the different vertical joints position and numbers,upper soil thickness and body water content of the tunnel entrance section.The results show that within the span of tunnel entrance,the joint has little effect on the vault settlement when it is at the middle of the vault;but the more joints deviate from the middle,the greater the vault settlement happens.When the joints develop at one side departing from the midline of the tunnel entrance arch,both the relative shear stress level and the area of plastic zone size of this side is greater than the other side,showing that the joints have adverse effect to the tunnel entrance section.When the joints occur on both sides of the arch,the plastic zone develops rapidly through the joints,and the central soil of the roof is cut by joints totally to form a dangerous landslide.