高速公路泥岩隧道围岩压力试验研究

以宝天高速公路天水过境段梁家山泥岩隧道为工程背景,通过现场测试,研究了围岩拱顶下沉、围岩与初期支护接触压力、钢拱架应力和初衬与二衬接触压力随时间变化规律及分布特征,并应用现有的理论和方法对实际工程安全状态进行评估。研究结果表明:以隧道开挖空间效应和Chern经验公式两种理论方法对拱顶沉降数据进行分析处理,所得到的隧道极限位移相差较小;围岩与初期支护压力的分布具有不均匀性特点;钢拱架外缘应力平均值大于内缘,拱顶处应力大于其他部位,按其推算得到的拱顶沉降极限位移更接近于实际情况;初衬与二衬间接触压力先迅速增加后逐渐较小最后趋于稳定,其稳定值整体偏小。

Test Study on Ground Pressure of Mudstone Highway Tunnel

Taking Liangjiashan Tunnel seated in mudstone of the Tianshui section of the highway from Baoji to Tianshui as an example, a comprehensive in-situ monitoring measurement was carried out for crown settlement, ground pressure between surrounding rock and primary support, stress in steel centering and contact pressure between primary support and secondary lining. The development and distribution characteristics of deformation and pressures of ground and structures were discussed based on measured data. The tunnel construction safety was then evaluated by using the analytical solutions. The results indicated that the ultimate crown settlement displacements calculated according to the methods proposed by Guan(1993)and Chern et al (2000)did not differ too much. The ground pressure and contact pressure were not uniformly distributed. The stresses on the exterior margin of steel centering were much larger than those on the inner margin with the peak values developed on the crown. Another calculation of ultimate displacement of tunnel crown settlement based on maximum stress on the inner margin of steel centering seemed to give a better assessment much closer to in-situ conditions. The contact pressures were increased quickly after lining concrete was poured and molded, but gradually decreased with time until they reached certain stable values which were slightly low.