Half Of The River Sub-tunnel Through The Rock Contact Zone Of The Construction Risk Control

There are mainly mountainous and hilly areas in southern China with topographic and geological conditions rather complex. The construction for highway tunnel encounters a number of complicated geological problems, and the tunnel rock contact zone is prone to geological disasters, under which engineering problems like how to ensure quality and reduce losses need to be solved. Set on RuCheng to Chenzhou Highway Banjiangzi tunnel, the construction risk of tunnel cut through the rock contact zone had been analysis and assessed based on the research on the rock contact zone of physical and mechanical properties, and corresponding risk control measures had been put up. Furthermore, the risk had been tracked. The main research contents as fellows:(1) Through indoor microscopic analysis of on-site rock samples, combined with field mapping of geological sketch profiles of rock contact zone, and the geological forecast results of the rock contact zone, the paper studies the gradual change feature analysis of tunnel surrounding rock in rock contact zone. Through the tensile compressive strength tests of rock contact zone's on-site rock samples, this paper analyzes the rock mechanical properties of the rock contact zone in Ban Jiangzi tunnel.(2) Combined the hydrogeology conditions, design and construciton of Banjiangzi tunnel and all kinds of researched results, this paper studies and assess the risk when Ban Jiangzi tunnel passed the rock contact zone.(3) Based on the risk analysis and assessment of Banjiangzi tunnel whick passed through the rock contact zone,construction and design measures had been taken to reduce the risk level with the Geological prediction. And the corresponding risk contingency plans was established for key points of the construction risk.(4) In order to evaluate the efficiency of risk control measures, this paper selects the typical profile to test the fall of roof, perimeter denection and steel arch's inner force. According to the results of test, It can guarantee requirement of rock stability and surpport structure forced after taking the design and contruction risk control measures when Ban JiangZi tunnel pass the rock contact zone, Consequently, to avoid the risk accident.