Feasibility Study On The Application Of Phase Change Materials In Anti-freezing Expansion Of Tower Foundation

Under the trend of China's economic growth,the power industry has made great achievements,and the power grid project has also grown stronger.Therefore,more and more transmission line projects are running in frozen areas.The problem of frost heave failure of the tower foundation also follows.As a new type of energy-saving temperature control raw material,phase change materials use themselves to absorb heat energy or release stored energy in a specific temperature range during phase transformation operation.Introduced into the field of anti-freezing expansion of the tower foundation,it can achieve the performance of controlling the ambient temperature.In theory,phase change materials can control the temperature of the soil around the tower foundation well.The research results have theoretical significance for reference in the application of phase change materials in the field of anti-freezing expansion of tower foundations.Based on the foundation engineering of 500kV transmission line tower in seasonally frozen ground,this paper studies the application of phase change materials in the anti-frost expansion of the tower foundation through experiments and simulations.The results are as follows:(1)This article selects the PCM-3 type phase change material produced by Shanghai Joule Wax,and uses ceramsite and slag as the carrier material.In the preparation experiment of phase change energy storage particles,the adsorption effect of ceramsite is better through the adsorption test results.And through the freeze-thaw cycle test,the encapsulation effect of epoxy resin-wrapped cement is better.(2)Make two box models,add ordinary soil and mixed soil mixed with a certain amount of phase change ceramsite inside the box,and measure the inside of the two boxes with a large volume concrete temperature tester.The results show that the internal temperature of the soil containing the phase-change ceramsite is higher than that of the ordinary soil,and the temperature of the soil containing the phase-change energy storage carrier tends to be stable without temperature mutation.(3)The ANSYS finite element simulation software was used to simulate and analyze the temperature field of the soil around the tower foundation,and analyze its change mechanism and the change of maximum freezing depth.The analysis shows that the freezing depth of the ordinary soil is 1.65m,and the freezing depth of the soil around the tower foundation after the replacement is 1.39m.At the same time,in order to obtain a reasonable replacement range,this article takes the foundation as the center and performs a replacement simulation analysis on the surrounding soil.The replacement range is 2.0m×2.0m×1.8m,2.5m×2.5m×1.8m and 3.0m×3.0m×1.8m,The simulation results show that it is reasonable to perform replacement in the range of 2.5m×2.5m×1.8m.(4)According to the principle foundation of elastic mechanics and the stress and strain finite element control equations of the soil around the tower foundation and the foundation,combined with the calculation results of the temperature field,an indirect coupling analysis model is established.By analyzing the stress on the tower foundation under two working conditions,the mechanism of stress change of the foundation after the phase change material is introduced into the soil around the tower foundation is obtained.