Dynamic Behavior Of Artificial Freeze-thaw Soft Clay Under Cyclic Loading

The construction of the coastal port city of underground rail traffic is greatly affected by the soft clay and groundwater,with the large-scale development and utilization of underground space,the artificial freezing method has apparently become a commonly used construction method of underground space development and utilization in soft soil area.The artificial freezing method construction process,control and evaluation of the soil strength of frozen soil displacement caused by frost heave,are key problems in engineering application,and the frozen soil excavation after the construction of a large number of residues around the tunnel in permafrost,with residual permafrost melts,the physical and mechanical properties of soil will occur significant change,focus on the effects of the changes are the scholars has been built on the structure and stability of the future will be built..Study on freezing conditions the engineering characteristics of saturated soft clay in Wenzhou area,underground space in Wenzhou area of artificial freezing construction has a very important guiding role.So far,there are few people in this research,this paper takes Wenzhou silt clay as the research object,the needle of artificial freezing engineering properties under construction in the area and the analysis of the following aspects:(1)samples of soft clay preparation has been a difficult problem,how to ensure the uniformity of style,isotropic ultra has always been a thorny problem,a new high-pressure consolidation apparatus used in this paper can solve this problem very well.But the changes in the structure of soft clay frozen thawed,so in order to prepare the sample prepared to move three axis to still have some difficulty,this paper designed a device for preparing frozen thawed soil system,greatly improve the freeze and thaw soil preparation success rate.(2)through different confining pressure of soil under undrained shear test,the freeze-thaw soft clay pore pressure,shear strength,stress-strain relationship.Soil after freeze-thaw,strength is significantly increased under low confining pressure,improve the strength of influence is especially remarkable.Also,can also be found in the hole the pressure of development,experienced soil freezing and thawing under different confining pressure has been lower than the untreated soil freezing and thawing.The strain development law and the regularity of pore pressure is similar.(3)through the preliminary.research on soft clay static test,the dynamic characteristics of the soft clay was also studied by dynamic triaxial test,three in sine wave loads the cumulative strain,pore pressure,stress-strain hysteretic curves,modulus of resilience development characteristics,found that after freezing and thawing soil with the consolidation characteristics,the indicators have been confirmed.(4)In order to better simulate the traffic load stress path,this paper adopts a hollow torsion shear apparatus,but because of freezing and thawing soil samples to prepared hollow shear,so this paper uses the same and thawing soil with super soft clay consolidation properties test,strain accumulation so as to put forward the prediction equations for calculation of settlement of overconsolidated soft clay in the traffic load.