Study On The Law Between Ground Deformation And Tunnel Face Support Pressure In Construction Of Shallow Cable Tunnel In Clay Formation

With the rapid development of the current construction of urban power grid,shallow cable tunnel has gradually become the main power transmission and distribution carrier of the urban power project which is 220 kV and above due to its big capacity,excellent heat dissipation and green environmental protection.The main method of cable tunnel construction in city is shallow construction whose major mean is pipe jacking.However,the surrounding soils will be disturbed in the process of construction,and one of the major influence factors is the pressure on tunnel face.Tunnel face pressure and ground deformation behavior in shallow cable tunnel construction are studied,the main work is as follows:(1)Survey and analyze the calculation methods of the pressure on tunnel face and the stratum deformation due to the pressure in shallow cable tunnel construction.On this basis,a modified formula considering the point location of earth pressure is derived.In addition,rationality of the modified formula is verified by combining with face support pressure and deformation calculation of an engineering project.(2)Numerical researches of tunnel face are done by the finite element analysis software ABAQUS.The effect law between tunnel face support pressure and tunnel face stability is studied by adjusting tunnel depth,diameter and soil properties.Through the analysis of tunnel face active and passive failure mode,the reasonable support pressure control range is preliminarily determined.(3)A large-scale geotechnical centrifuge model test which contains active and passive failure on tunnel face is carried out by applying the support pressure respectively.Changing laws of soil stress field and displacement field with support pressure are recorded.Relationship between different tunnel face support pressure and strata disturbance is studied.(4)The tunnel face stability and failure mechanism are studied by comprehensively analyzing the results of theoretical analysis,numerical simulation and centrifuge model test.The reasonable support pressure control range is determined.The research results can provide reference for tunnel construction technology which applied in the underground cable engineering.