The Study On Large Deformation Causes And Control Technology Of Carbonaceous Schist Tunnel In Xiangfan-Chongqing ? Railway

With the engineering background of large deformation of carbonaceous schist tunnel in Xiangfan-Chongqing ?railway,based on field measurement,laboratory test and analysis of rock mechanics by elastic-plastic theory,this paper researches and analyzes about nature of carbonaceous schist and characteristics of thick carbonaceous schist mechanics,deformation characteristics of tunnel,factors influencing deformation and deformation mechanism.At the same time,the original design and the initial supporting parameters optimized were studied in detail by using shear-slip method,this paper also studied construction site management for the carbonaceous schist tunnel.Taking advantage of the in-site monitoring data of underground engineering,the carbonaceous schist deformation rules are concluded including the deformation lasts long,the part of secondary lining still exist deformation,asymmetry of deformation,horizontal convergence which is significantly greater than the vault crown settlement,the deformation rate which is relatively large,larger deformation of horizontal convergence and various supporting destructive forms.This paper analyzes through the mineral composition in carbonaceous schist,the section shape,the original design supporting parameters,construction method,the mode of contractor management and other factors to find the main factors.The supporting parameters is determined by the engineering analogy method,and using the elastic-plastic theory of rock mechanics,rationality of design parameters are calculated through shear-slip method,the reinforcement layer thickness is determined so as to avoid the limitations of the engineering analogy method.Through the optimization of management mode,we can further strengthen the site management and successfully control large deformation of carbonaceous schist tunnel.Based on the analysis of the measured data,the reasonable construction step size and secondary lining construction time are determined.Combining the engineering case of controlling the large deformation of carbonaceous schist and research about geological factors,measured data,Design parameters,construction method,project management and so on,this paper develops a successful technical measures and management measures,it provides an important technical support for the successful construction of the project,and also provides some reference for the construction of soft rock large deformation tunnel.