| In the process of earthquake,the foundation soil is subjected to the coupling action of horizontal shear stress in different directions,and the stress path of soil is extremely complex.In addition,the mudflat soil foundation which has not yet reached the state of complete consolidation deforms greatly,and is easily unstable under static and dynamic loads.Therefore,it is extremely necessary to study the static and dynamic response characteristics of soft clay with low degree of consolidation under different stress paths.It can provide some reference basis for the design and construction of the structures on the beach land foundation in the coastal area.In this paper,a series of static and dynamic tests were carried out on Wenzhou remolded soft clay by using direct shear apparatus and dynamic single shear apparatus.The static and dynamic response characteristics of Wenzhou remolded soft clay under different degree of consolidation were analyzed.The main contents are as follows:(1)Strain-controlled direct shear tests were carried out on Wenzhou soft clay with different degree of consolidation,and the effects of different vertical consolidation stress,shear rate and degree of consolidation on the shear characteristics of Wenzhou soft clay were analyzed.The test results show that the shear strength of soft clay increases with the degree of consolidation,showing a significant nonlinear relationship.When the degree of consolidation is low,the shear strength increases rapidly with the degree of consolidation.When the degree of consolidation is high,the shear strength of soil tends to be gentle with the increase of degree of consolidation.Based on this,the concept of critical degree of consolidation of soil were obtained,and the critical degree of consolidation for Wenzhou soft clay is between 0.65?0.85.Further results show that the critical degree of consolidation is independent of the vertical consolidation stress and shear rate.(2)A series of unidirectional cyclic stress path single shear tests were carried out on soft clay with different degree of consolidation,and the effects of degree of consolidation,cyclic stress ratio and number of cycles on the cyclic characteristics of soil were discussed.The results show that there is a critical cyclic stress ratio under the path of one-way horizontal shear stress.When the shear stress applied is less than the critical cyclic stress ratio,the shear strain increases slowly at the beginning of loading,and then reaches a stable value,and the generated shear strain is far less than the failure criterion of soil.When the shear stress applied is greater than the critical cyclic stress ratio,the soil can reach the failure point at fewer cycles.The further study results show that the degree of consolidation has a great influence on the critical cyclic stress ratio of soil,and the higher the degree of consolidation causes a greater the critical cyclic stress ratio of soil.(3)Dynamic single shear tests were carried out on Wenzhou soft clay under twoway horizontal shear stress coupling.The effects of stress path,degree of consolidation and cyclic stress amplitude under circular stress path on the dynamic response of soft clay were studied.The development rules of shear strain,strain path,hysteresis cycle and shear modulus of soil were analyzed.It is found that the larger phase difference of shear stress results in larger the shear strain,and the faster growth rate of the strain.When the phase difference is the same,with the increases of the degree of consolidation,the shear strain gradually decreases,and soils need more cycles to reach the failure point.With the increase of the cyclic stress ratio,the area of the hysteretic loop gradually increases and approaches to the transverse axis,which indicates that the attenuation response of soil stiffness is intensified.In addition,the hysteretic cycle difference between samples with different degree of consolidation increases with the increase of cyclic stress ratio. |
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