Study On Tunnel Construction In Watery And Weak Stratum Of Completely Decomposed Quartzite

With the development of construction in the engineering field, more and more tunnels are constructed in the layers of rich water, weak or fractured-surrounding rock and geological/hydrological conditions. In this case, some auxiliary measures like reinforcement treatment to ensure excavating smoothly are needed. Based on the tunnel crossing through fully weathered quartzite layer in rich water, the construction technology for excavating in rich water and weak rock has been studied, which can provide reference for other tunnel project. The main achievements are:(1) In order to know some mechanical parameters and geological characteristics of surrounding rock, physical mechanical performance has been analyzed by means of field sampling. As a result, the parameters used for numerical calculation or model test are acquired.(2) The effects of Horizontal-Jet-Grouting pre-reinforcement are analyzed and the construction methods applied after reinforcement are selected for comparison. The calculation result shows that the method of Horizontal-Jet-Grouting pre-reinforcement can reduce surrounding rock settlement effectively.(3) Based on the tunnel surrounding rock conditions of weak and fractured and developed ground water, a scheme of Horizontal Jet Grouting pre-reinforcement has proposed. The construction effect shows that Horizontal-Jet-Grouting pre-reinforcement can largely improve self-bearing ability of surrounding rock, which has ensured the excavation and construction safely.(4) The designing and construction method for the tunnel crossing through weak and rich water surrounding rock have been analyzed, which include designing scheme and parameters of waterproofing measures, pre-reinforcement of surrounding rock, the excavation of tunnel, supporting structure and so on. Thus, a kind of construction control technology for the tunnel excavate through the layers of rich water and weak surrounding rock has acquired.