Limit Analysis Of Shallow Tunnel Grouting Reinforcement Stability In Clay

With the continuous development of world economy, the transportation plays a positive role in promoting the national economy, but due to the decrease of land resources, the tunnel engineering in the construction of transport infrastructure in the proportion is growing. Therefore, the security problem is the question of the tunnel must be considered in the construction process,which includes the deformation and stability of these two major issues. This paper is to study the stability of shallow clay tunnel.The main research contents are:① Through analysis of relevant literature to determine the stability of the tunnel as the research method of upper bound method and analytic method, the reinforced and unreinforced tunnel is studied using the above methods, and the tunnel was strengthened with small pipe grouting technology, strengthening scheme for the "120°dome reinforcement".② The upper bound method is used to optimize the failure mechanism of reinforced and unreinforced tunnel to obtain the critical state stability coefficient for the evaluation of the tunnel and the shear strength of the known prerequisite for tunnel critical support pressure surface under additional pressure distribution =0Ss.③ According to the reinforced and unreinforced unnel displacement formula get vertical and horizontal displacement variation and draw the displacement vector picture of soil around the tunnel. The reinforcement and unreinforced tunnel stability coefficient, variation of the vertical and horizontal displacement and displacement vector picture comparison, summed to obtain a small pipe tunnel grouting reinforcement to improve the stability of the vertical and horizontal displacement constraint changes.④ The analytical solution of the optimization of reinforced and unreinforced tunnel failure mechanism, that is integral to the polar coordinates difference equation to get the critical support pressure when the additional surface pressure distribution =0Ss in the known shear strength, and the tunnel stability coefficient of the critical state.⑤ According to the study, it were obtained with the variation of the tunnel cave largest settlement Sm-Ts and volume loss rate VL-Ts under the reinforced and unreinforced tunnel. Then their settlement patterns and volume loss rate comparison, reinforced tunnel subsidence and volume loss rates are relatively small, description of advanced small pipe grouting reinforcement to enhance the stability of the tunnel.⑥ The reinforcement of the tunnel stability coefficients were compared, it was found the optimum value of the maximum method, analytical solution is the upper limit, consistent with the actual research project illustrates the effectiveness of these two methods.In this paper, through optimizing the solution process on the stability of the tunnel with upper bound method and analytic method, and study the soil around the tunnel cave settlement laws, and discusses the rationality of the optimized method of settlement, it has the reference significance on study the stability of the tunnel and the soil around the tunnel for the future.