Study On Comprehensive Construction Technology Of Large Section Tunnel In Third Water Rich Fine Sand Formation

Based on the construction of Lanzhou-Chongqing railway Tao Shu Ping tunnel with large cross section,studies the comprehensive construction technology of large section of passenger dedicated tunnel crossing third lines of water rich silty sand layer,to solve the problem of precipitation and construction stability existing in tunnel construction,the main work and achievements are as follows:(1)Through the analysis of the Tao Shu Ping tunnel hydrogeological conditions,determined the precipitation measures can be used in tunnel construction;through the construction practice of the scene,eventually using the vacuum light well point precipitation,precipitation of deep well dewatering scheme,comprehensive advanced precipitation combined with each other,to achieve the effective precipitation in water rich sand stratum,excavation for tunnel to create a favorable environment for construction.(2)According to the geological condition of Tao Shu Ping tunnel,and construction method of large section tunnel,initially identified the next cross,double heading ahead of the three kinds of construction schemes and double column method.(3)By using the numerical simulation analysis of construction process of the construction of the three methods,the change of different construction of surrounding rock displacement in the stress variation and stress and deformation characteristics of supporting structure changes.The numerical analysis shows that the double heading advance method excavation of the vault settlement is far less than the CRD method and the settlement method of double column vault,double heading advance method of settlement of vault settlement is 58% CRD,is the 73% generation of double column settlement method.Based on numerical simulation analysis,it is confirmed that the double hole advance method is the best construction scheme.(4)The construction of track tunnel,selection of typical section for monitoring dynamic response of tunnel construction;on-site monitoring data analysis shows that the double heading advance method has a good effect on the stability of surrounding rock,can adapt to the construction of water rich sand stratum is very good.