Study On The Cracking Mechanism And Reinforcement Scheme Of Bell Tunnel Support Structure On HighwayS302in Sichuan

With the advance of China’s economic construction, transport requirement of the central and western regions dramatic increase, leading to the emergence of a variety of high-grade road and rail. Because of the central and western regions of complex terrain and geological conditions, road or rail routes often pass through poor geological sections, and improvement of tunnel scheme itself is linear, shorten the mileage and trave time, improve operation efficiency, therefore the construction of the railway and highway in the right place uses a lot of tunnels, so contribute significantly to the construction of the tunnel, For various reasons, many tunnels there are different degrees of disease, seriously affecting the normal operation of the line. In this paper, a method of reinforcement is proposed when tunnel lining produced a wide range of ring cracks as a result of the axial tension, this paper systematically study the reinforcement structure, the main contents and results are as follows:(1) According to the characteristics of the tunnel crack cracking the mechanism has been analyzed, the geo-mechanical models are summaried; on this basis, this paper proposes a new reinforcement structure. The reinforcement principle of new structure is fully use tunnel lining, this reinforcement means use anchors through broken rock to let tunnel fix in stable bedrock, cable into a small angle with the tunnel axis direction, so that cable can provide the axial direction more contribute to resist lining axial tension applied by the broken rock s urrounding the tunnel, change the root causes of the unfavorable state of the force lining(2) This paper analyzes the struture of the new reinforcement struture, the influence of the new reinforcement structure internal forces has a correlation analysis by the change of the main parameters, results show that:the displacement and internal force of the tunnel structure increases; the displacement and internal force of the lining have a significant change with the cable angle change; the displacement and internal force of the lining have a small change with the cable length change and the anchor stiffness change.(3) This paper calculates the displacement and internal force of the tunnel structure by use the numerical software to simulate the new structural to reinforce the SiChuan bell tunnel, the results show that the new structure is effective and feasible, the internal force and displacement of reinforcement structure is very small..