红黏土隧道围岩含水率变化及变形特征分析

银西高速铁路庆阳隧道洞身主要围岩为红黏土。本文通过现场监测,对庆阳隧道从初期支护开始近2个月内围岩含水率、钢拱架应力及围岩变形的变化规律进行分析。结果表明:红黏土隧道围岩含水率、钢拱架应力和围岩变形先增大而后趋于稳定;含水率和钢拱架应力的增长波动期一般为2~4周,围岩变形增长期一般为2周;含水率趋于稳定后拱顶和拱腰处围岩含水率明显小于拱脚和仰拱处;增长期围岩变形线性增大,变形基本稳定后拱顶沉降大于水平收敛;钢拱架承受围岩压力,对确保红黏土隧道围岩的稳定起着重要作用。

Analysis of Water Content Change and Deformation Characteristics of Surrounding Rock of Red Clay Tunnel

The main surrounding rock of Q ingyang tunnel in Yinchuan-Xi an high speed railway is red clay.Through on-site monitoring,the change rules of surrounding rock water content,steel arch stress and surrounding rock deformation of Q ingyang tunnel in nearly two months from the initial support were analyzed in this paper.The results show that the water content of surrounding rock,the steel arch stress and the surrounding rock deformation of red clay tunnel increase f irst and then stabilize.The growth f luctuation periods of surrounding rock water content and steel arch stress are generally 2~4 weeks,and the growth period of surrounding rock deformation is generally 2 weeks .When the water content tends to be stable,the water contents of the surrounding rock at the vault and waist are obviously less than that at the arch foot and inverted arch.The deformation of surrounding rock increases linearly during the growth period and the vault settlement is larger than the horizontal convergence after the deformation is basically stable.Steel arch bears the pressure of surrounding rock,which plays an important role in ensuring the stability of surrounding rock of red clay tunnel.