Study On Deformation Characteristics Of Soft Clay Under Multi-directional Coupled Stress Paths Caused By Traffic Load

Deep saturated soft clay is widely distributed in the southeast coastal areas of China.Such as expressway,railway,airport runway and so on,which are established on the soft clay foundation,causing strain accumulation and strength degradation of the subgrade clays soil,excessive deformation and instability under the static action of the static load of the embankment and the repeated dynamic action of the traffic load.A series of problems threat to the people's property and life safety.Therefore,it is urgent to study the effective control of soft clay foundation settlement technology,in order to improve the long-term service performance of traffic engineering,reduce the loss of national production.In this paper,ABAQUS finite element software is used to analyze the stress of soft clay foundation under the action of traffic load.Then,a series of experimental studies which the dynamic characteristics of the traffic load stress path are conducted on through GDS hollow cylinder system by using the hollow cylindrical specimen which is prepared by reconstructing the soft clay prepared by the soft clay in Wenzhou.The detailed work and achievements are as follows:According to the actual stress conditions of soft clay subgrade under the action of traffic load,the 3D pavement-subgrade model is established by ABAQUS finite element software.The static load and dynamic load are applied to the road surface to obtain the stress state in the subgrade soil.The whole vehicle passes through a unit in the subgrade,the vertical stress is changed into half sine wave,and the horizontal stress is first rises after falling to 0,rising from 0 in the downward trend,while the shear force is expressed as a complete sine wave.The variation of the vertical additional stress is linearly related to the magnitude of the load and obtained the stress ratio at different depths,It is used to determine the test scheme.Based on the results of ABAQUS finite element software research,the experimental study on the stress path from easy to complex traffic load is carried out.The results show that the strain,cumulative pore pressure and resilient strain of the specimen increase with the increase of the CSR,and the modulus of resilience is negatively related to the CSR whether it is the cyclic triaxial test,cyclic torsional shear test,the circulating confining test and multi-direction stress coupled cycle test.The strain and cumulative pore pressure of the specimen increases with the increase of t? and d? in multi-direction stress coupled cycle test,there is a special case when the shear stress is 0.the empirical equation of cumulative strain under long-term cyclic loading is established in the experiment considering the c oupling of stress.Consideration of the factor of load frequency.Respectively,at three frequencies(f=1,0.1,0.01)considered the cyclic torsional shear test,the cycle confining test and the multi-direction stress coupled cycle test,there is deep analysis of the strain,cumulative pore pressure,resilient strain and resilient modulus in the different frequency and different stress path test,the strain and cumulative pore pressure of specimen is increased at low frequency,and the resilient behavior is discussed according to the difference of stress path of the specimen.