黄土隧道围岩含水率变化及拱架受力特征研究

Research on the Characteristics of Steel Arch Stress and Variation of Water Content of Loess Tunnel Surrounding Rock

为了研究黄土隧道围岩含水率和钢拱架应力在施工期间的变化规律,以在建银西高铁董志塬区上阁村隧道为例,采用现场监测方法,对黄土隧道围岩体积含水率变化规律和钢拱架受力特征进行分析研究。结果表明:黄土隧道围岩含水率在时间上呈先增长后平稳的两阶段变化,在空间上表现为拱顶和拱腰位置的含水率总体小于拱脚和仰拱底部的含水率;钢拱架应力在施工期内呈先非线性增大后出现波动最后趋于平稳的三阶段变化规律,在施工期内钢拱架对承受围岩压力、确保大断面黄土隧道围岩稳定性方面发挥着重要作用。建议对大断面黄土隧道在施工期内形成"勤测含水率、重视防排水、加强初支"的管理理念。

In order to research the change laws of the water content of the surrounding rock and the steel arch frame stress of the loess tunnel during construction period,the variation of water content of the surrounding rock and stress characteristics of the steel arch frame are analyzed and studied based on field monitoring with reference to Shangge Village Tunnel of Yinchuan-Xi’an High-speed Railway in Dongzhiyuan region. The results show that the water content of the surrounding rocks of the loess tunnel increases firstly and then changes steadily,and the water content of the vaults and haunch is generally less than that of the skewback and the bottom. The steel arch stress shows a three-stage change of nonlinear increment first,then fluctuation and gradual stability in the construction period,and the steel arch frame plays an important role in bearing the pressure of the surrounding rock and ensuring the stability of loess tunnels of large section. The management concept of 'diligent measurement of water content,emphasis on water prevention and drainage,strengthening of initial support'is recommended for loess tunnels of large section during the construction period.