Study On Construction Optimization Of The Layered Rock Tunnel And Its Engineering Method Based On Contact Analysis

Layered rock mass are widely distributed in our country.It is very common for tunnel constructed to cross the layered rock.The soft and hard interbed rock is the most typical.The near horizontal soft and hard interlayer rock mass is widely distributed in the western region.The bedding will affect the whole process of tunnel construction.The bedding effect makes poor adhesion strength between the horizontal strata interlayer,that will go against the stability of surrounding rock in the process of tunnel excavation.For supporting,the bolt support technology is difficult,low reliability and inappropriate when bedding exists.This paper based on the Simianshan mountain tunnel engineering which is surrounded with sand mud interbed rock at the level of V.Firstly,for the near-horizontal soft and hard interlayer surrounding rock tunnel excavation,a new simulation method based on contact analysis was put forward,which can also simulated the complete process of tunnel construction.The influence on the stability of the surrounding mountain tunnel with different construction methods were also studied,and proposed the preliminary construction suggestions.Then,on the basis of the simulation method,the deformation and structural stress characteristics of the Simianshan tunnel on the effect of different construction ways was studied.Further more,the construction parameters of the Simianshan tunnel were optimized.At last,the construction method applicable to the near horizontal soft and hard interlayer tunnel was put forward.The main research content and conclusions were as follows:1)Combined with the Simianshan mountain tunnel project summary,a new tunnel construction simulation method based on contact analysis put forward,and the characteristics of tunnel deformation,bedding displacement and linning structure stress of the hard and soft interbed surrounding rock were obtained,and the excavation method was simulated,then the comparison of different excavation methods for the Simianshan mountain tunnel was carried out,and.the field construction was carried out to verified.2)From the view of economy,used the enumeration method to optimize the initial supporting parameters for the Simianshan mountain tunnel engineering from the aspects of the amount of the bolt,then put forward the corresponding design suggestions for the primary support.3)From the view of construction efficiency,used intelligent optimization method to optimize the construction technology for the hard and soft interbed surrounding rock of Simianshan mountain tunnel engineering,optimized the stairs lead length,the time to excavate the down steps and the second lining support time,then put forward the corresponding design suggestions for the construction technology.4)For the optimized parameters of tunnel construction,field test verification was carried out.According to the measured value of tunnel deformation during the monitoring period.Extract the simulation value of the tunnel site monitoring time which was realized by the method of numerical calculation.Making comparision between the both,and conclude that the optimization scheme is feasible.5)Combined with the tunnel construction process,from the quality,safety,environmental protection and other aspects,the corresponding suggestions were put forward,and the relevant technical and economic benefits were analyzed,then the construction method for the tunnel engineering surrounded with hard and soft interbed rock was put forward.