Study On The Influence Of Mechanical Properties Of Frozen Soil On Bearing Capacity Of Pile Under Freeze-thaw Cycles And Temperature

With the global warming,the rate of degradation of permafrost was accelerated,and the influence of the mechanical properties of frozen soil on the bearing capacity of pile is becoming more and more significant.At present,the influence of the mechanical parameters on the bearing capacity of the frozen soil under the influence of the freeze-thaw cycle and the temperature has not yet reached the conclusion.In this paper,the silty clay in the high temperature permafrost region was selected to carry out the laboratory test,and the freezing and thawing cycles were analyzed.The results showed that the freezing temperature of the frozen soil was higher than that of the frozen soil.The influence of freezing and thawing cycle and temperature on the bearing capacity of pile foundation is studied by means of numerical analysis method,and the working results are as follows: the effect of freezing and thawing cycle and temperature on the bearing capacity of pile foundation is studied by using ABAQUS software.:For the freeze-thaw cycle,the mechanical properties of the soil would be changed.The reconstructed soils were subjected to 0,1,3,5,7,10,20 freeze-thaw cycles respectively.The effect of freezing and thawing cycles on the shear strength index was studied.The results show that owing to the increase of the number of freeze-thaw cycles,the cohesion of the soil decreases nonlinearly and the internal friction angle was slightly increased.After the freezing and thawing times,the cohesion and internal friction angle of the soil were kept constant.The soil strength parameter degradation model was established based on the Mohr-Coulomb 's law,and the geotechnical parameters were provided for the subsequent numerical analysis.In order to solve the problem that the shear strength of permafrost in high temperature permafrost area was significantly changed by temperature,the temperature was at-4 ?,-3 ?,-2 ?,-1.5 ?,-1 ?,-0.3 ? and 0 ?.The effect of temperature on the strength parameters of remolded soil samples was studied by direct shear test.The results show that the cohesion and internal friction angle of soil increased with the decrease of temperature,and the effect of temperature on internal friction angle was much less than that on cohesion.When the temperature decreases from-0.3 ? to-1 ?,soil cohesion increased by 50.1% because of ice content increasing and soil structural changed.Based on the shear strength parameters obtained from the laboratory test,ABAQUS software was used to analyze the influence of the number of freeze-thaw cycles and the temperature of permafrost on the bearing capacity of pile foundation.With the increase of the number of freeze-thaw cycles,the freezing force of the pile side increases and then decreases in the depth direction of the pile,reaching the maximum at the height of the pile body,the ultimate bearing capacity of the single pile is gradually reduced,and the freezing-The ultimate bearing capacity of single pile is reduced by 32.26% when the temperature rises from-1 ? to-0.3 ?,and the ultimate bearing capacity of single pile decreases with the increase of formation temperature.