Study On The Stability Of Surrounding Rock Of Ji Jia Po Tunnel In Wu Shen Speedway

This article relies on Wushen speedway Jijiapo tunnel project, in finishing the project area’s geological data base tunnel design support program, combined with the geological prediction, monitoring, measurement and numerical simulation analysis of three aspects to a comprehensive analysis.Predict geological conditions ahead is to ensure construction safety, a prerequisite for the stability of surrounding rock of the construction process, the first comparison of various types of geological prediction method found a single and advanced geological prediction means not very good on forecast the front of the geological, often require a variety of detection methods The integrated use to make up for their shortcomings, to form a more complete address ahead of forecasts, provide strong protection for construction safety. Ji jia po tunnel the main use the method of Geological sketch, TGP, and geological radar three kinds of method.Monitoring and measurement is an important method to guide the construction, through the analysis of data processing, can effectively carry out a general anticipation on the stability of surrounding rock, and the collected data is often associated with time and space has a certain regularity, the change curve of four kinds of. On the basis of the provisions in the judge the stability of surrounding rock, analysis of surrounding rock stability can be obtained through the tunnel on the collation of data, and the working face is about 3 times of the diameter of the tunnel, can do the second lining.This paper mainly through the software of finite element numerical simulation analysis of small clear distance tunnel in different cover thicknesses, shallow buried section of different excavation sequence effect, deep buried different rock, deep buried sections with different spacing and the influence of different construction methods for the deep buried. The following conclusions can be obtained: the deformation of surrounding rock increases with the coating thickness increases; the first excavation deep cavern excavation of shallow buried side after side cavern is more conducive to the stability of surrounding rock; rock deformation decreases with the increase of the level of the surrounding rock; 14 m may be the best of the small spacing tunnel clear distance; CRD method is the best construction methods and steps the construction method is the most simple method.At the same time, due to the poor stability of surrounding rock will seriously affect the second lining work safety, and in the process of construction, at the top and shoulder of second lining,because of concrete filling density, the thickness is not enough. The innovation of this paper lies in the security analysis of unequal thickness the second lining of shallow bias section, analysis shows that with the decrease of vault and spandrel position, thickness, axial force of the second lining showed increasing trend, but the moment is showing a decreasing trend, the safety coefficient and the second lining all decreased, lining damage range increased. The conclusions can provide a reference for practical engineering design and construction, timely support and prevention work.