Study On Reserved Deformation Of Shallow - Buried Soft Rock Tunnel With Large Section

With the development of economic and investment of national infrastructure. Highway construction has entered a new period of development. Combined with the national One Belt One Road strategy, Southwest is the hub of transportation network will gradually constitute. Construction of high grade highway in southwest mountainous area, tunnel has been widely used, because the Advantages of ensure operational safety and to avoid damaging the ecological environment and shorten the mileage. The large deformation of soft surrounding rock tunnel is one of the important problems which threaten the safety of tunnel, To solve the problem of large deformation of surrounding rock, in addition to supporting measures, there is a way to solve this problem, that is to determine the reasonable amount of reserved deformation, so that the release of the surrounding rock deformation and stress, in order to ensure the safety of the two lining. Compared with the complex control of large deformation of surrounding rock, the surrounding rock has a reasonable amount of deformation, and in the process of tunnel excavation to do a good job in the deformation is more economical and reasonable. In this paper, take the zhongHe tunnel as the engineering research object, We study the tunnel buried under different depths and different levels of conditions surrounding rock deformation variation with time and space and get set aside the amount of deformation range, hoping to provide reference for the design and construction process similar projects.(1) Rheological properties of the surrounding rock has found the actual monitoring process,In the use of MIDAS/GTS to build a tunnel model, the choice of elastoplastic-viscoelastic constitutive model coupled to V Tunnel with simulated excavation, elastoplastic model with paragraph Ⅳ surrounding rock tunnel excavation simulation. In the depth of 30m, 60m,90m,120m under the circumstances, and analysis of tunnel surrounding rock deformation of the deformation range, and set aside in order to determine the magnitude of the deformation range.(2) According to on-site monitoring data, V surrounding rock by statistical analysis of large amounts of data segment, Adopt a certain guarantee rate conditions to determine the tunnel reserved for the amount of deformation value, Then combined with numerical simulation results to determine the V surrounding rock section of tunnel reserved deformation of 30～35cm, and in the next V surrounding rock tunnel excavation process, through on-site monitoring and analysis found that the reserved amount is better, the phenomenon of tunnel surrounding rock is greatly reduced.(3) In the tunnel excavation to the IV surrounding rock mass, the method of guarantee rate cannot be used to determine the amount of the reserved deformation because of the monitoring data. In this case, according to the numerical simulation results and combined with the design data to set the value of the amount of deformation, and finally to determine the value of the IV surrounding rock 15-20cm, Engineering verification of the reserved deformation by monitoring the measurement method, It is found that the amount of deformation is feasible. The results show that the results of numerical simulation can be used for reference.