Analysis Of Mechanical Properties Of Utility Tunnel And Soil Under Traffic Load

The utility tunnel,also called the common ditch and the municipal comprehensive ditch,is a public infrastructure containing more than two different functions.According to statistics,our buried pipeline accidents happen every day as high as 5.6 in average causing huge direct or indirect economic losses,therefore,our country is energetically promoting the construction of utility tunnel.however,due to the geographical conditions and economic,many utility tunnels are laying in soft soil.Soft soil has low strength,high compressibility,small permeability and rheological property,which makes it difficult to build utility tunnel in soft soil foundation.Utility tunnels that embedded in soft soil are easy deformation and destabilization caused by excessive differential settlement under interaction of soil and traffic load.As a result,the reliability and safety research of utility tunnel under traffic load and soil is of great significance for social development and engineering.Research of utility tunnel is mainly focused on its seismic response,rarely consider the influence of traffic load.Based on the the domestic and foreign research of utility tunnel and traffic load,using ABAQUS to study on traffic load,structure-soil and pile interaction,the dynamic and static response of utility tunnel,then compare the results with the theoretical analysis to verify the correctness of the theoretical analysis and the rationality of the model.The contents of the study are as follows:(1)Analyze soil pressure around the utility tunnel by upper bound method of limit,construct multi rigid blocks translational failure line to determine the failure mode,theoretically deriving the additional stress under traffic load.The calculation results show that the theoretical results match well with simulation results,The method can be used for the initial design so as to improve the construction of the utility tunnel correspondingly.(2)Using ABAQUS build a three-dimensional solid model,explaining the constitutive relation selection,failure criterion and contact between soil material andconcrete material.Analyze the dynamic and static responses of the model under traffic load,then discussing different effects of vehicle speed,depth,soft substratum modulus and load time.(3)Based on the idea of controlling settlement caused by strain and delaying consolidation of foundation,using cement soil pile to solve the large settlement.Comparing the results we can know that foundation treatment can effectively reduce the settlement caused by traffic load and uneven settlement of utility tunnel and surrounding soil.Methods and results presented in this paper will provide some theoretical basis and reference for further research on mechanical properties of utility tunnel in soft soil area under traffic load.