Study On Seasonal Coupling Of Sand Channel Foundation

There are many seasonal frozen soil regions in Northwest my country,Northeast China,Ningxia and Gansu.The area of seasonal frozen soil accounts for about 53.5%of the country’s land area.In the seasonally frozen soil area,in winter,when the ambient temperature is lower than the freezing temperature of the soil,the pore water inside the soil undergoes phase transformation to form pore ice.At this time,in-situ freezing occurs because the volume of pore ice is larger than the pore water.Therefore,the soil volume expands and squeezes the soil particles to form frost heave;in spring,the ambient temperature rises,causing the pore ice inside the soil to melt to form pore water,which leads to saturation or supersaturation of the soil,thereby reducing the bonding between the soil particles.Under the action of the upper load,the phenomenon of melting and sinking occurs.Mainly manifested in the uneven subsidence of roads,railways,various infrastructure roadbeds,pavement tumbling and mud,various foundation engineering slopes instability,and the cracking of the supporting structure of cave tunnels.On the whole,my country’s research on frost heave and thawing settlement of frozen soil has a relatively extensive environmental background and engineering background.Therefore,in this paper,for a project in Yulin area,the physical parameters of the test sand are determined through laboratory tests,combined with the ground temperature and meteorological data in Yulin area,the cold end and warm end freezing temperatures of the test are selected,as well as the moisture content of the sample.In order to monitor the normal frost heave force,normal displacement and real-time water replenishment of silty sands in Yulin area,based on previous studies,a set of self-developed sets that can realize top-down one-way freezing and bottom-up The frost heave device required for pressure less water supplement.This article discusses and studies the water-heat migration and thermo-mechanical coupling of artificially frozen silty sands.The main contents are as follows:(1)Based on the indoor one-way freezing test,4 different cold end temperatures(-10℃,-15℃,-20℃,-25℃)and 3 moisture contents were carried out on the artificially frozen sand cylindrical samples.(10%,17%,25%)unidirectional freezing test,analyzed the influence of different cold end temperature and initial moisture content on the temperature field,moisture field and displacement field of frozen sand.(2)Based on the second development of the COMSOL Multiphysics software PDE module,derive an unsaturated positively frozen sand hydrothermal coupling model,establish a frozen sand hydrothermal coupling numerical simulation and a thermomechanical coupling numerical simulation,and compare the simulation results with the experimental results.Analyze the adaptability of this model.(3)In this paper,based on the indoor one-way freezing test on the hydro-thermal and thermo-mechanical coupling analysis of silty sand,the inversion analysis method is used to analyze the side channel with silty sand as the foundation.Numerical simulation of hydro-thermal coupling at the rate.This paper is based on the study of the mechanical properties of artificially frozen silty sand in a certain area of Yulin area,which can provide a certain theoretical basis for the artificial freezing method of the silt Provide a certain reference value for the prevention and control of frost heave and thaw sedimentation.Figure[41]table[8]reference[65]...