隧道原位单侧扩挖围岩力学特性解析分析

Mechanical Characteristics Analysis of Surrounding Rock of Unilateral Expansion Tunnels in Situ

为通过解析计算分析隧道单侧扩挖围岩力学特性的特点,考虑到围岩支护对隧道围岩的稳定起到重要作用,针对已有的隧道围岩力学解析解,在考虑支护反力作用的情况下,结合Schwarz交替法进行求解,提出了隧道原位扩挖围岩力学特性计算的解析算法。经大帽山隧道原位扩挖工程的围岩变形监测数据与abaqus数值模拟验证,结果表明:在考虑支护情况下隧道原位扩挖Schwarz交替法能得到较精确的围岩力学性质,该方法有较好的适用性。随着扩挖宽的的增加其围岩特性如下:(1)在相切处即原隧道在开挖施工部分应力值变化较大,扩挖部分的环向应力在拱顶处有拉应力产生。(2)原隧道竖向,水平位移值变化较小,较稳定。扩挖部分的竖向位移有增大趋势,水平位移有收敛趋势。(3)相较于无支护的情况,有支护力作用下,隧道扩挖水平位移变形趋向于稳定,竖向位移变化较小。

In order to analyze the mechanical characteristics of tunnel side wall rock mass by means of analytical calculation,considering the tunnel lining plays an important role to keep the stability of surrounding rock in practical engineering,according to the analysis of the existing tunnel surrounding rock mechanics solutions,in the case of considering supporting force,combined with Schwarz alternating method,a calculation analysis algorithm of the surrounding rock deformation was provided. Construction between the surrounding rock deformation monitoring data and ABAQUS numerical simulation of the Damaoshan tunnel engineering show: in the case of considering support, tunnels expansion in situ Schwarz alternating method can get more precise surrounding rock mechanics properties of the expansion tunnel,the method has a better applicability. With the enlarging widths of the tunnel,its features are as follows: ( 1) At the tangent place of hole1 and hole 2 i. e. excavation construction part,the stress changes of the original tunnel is bigger. At the hole 2 i.e. expansion digging part,hoop stress has tensile stress in the vault. ( 2) Along the vertical,horizontal displacement of the original tunnel values change little,which is relatively stable. At the digging part,the vertical displacement has increasing trend,expanding horizontal displacement has a trend of convergence. ( 3) Compared with no supporting force,when there is supporting force,the tunnel expansion horizontal displacement tends to be stable,and the vertical displacement change is smaller.