| As the rise and development of geothermal energy development and utilization,more and more problems of soil heat and moisture transfer are encountered in engineering practice,and related research has become a hotspot of academic research.The soil heat and moisture migration is affected and restricted by many factors,so it is necessary for different influence factors were studied.In this paper,a one-dimensional soil column experiment platform is built based on the heated soil in actual stratum.Based on the experimental bench,the one-dimensional soil moisture and heat transfer experiments were carried out in different soil types,different thermal heat(cold)source temperatures,different initial water content,different compaction times(porosity),and different initial temperatures.The soil types include: gravelly sand,coarse sand,medium sand,fine sand,silt and clay.The heat(cold)source temperature include : 30℃,40℃,50℃(15℃,10℃,5℃).The initial water content include : 5%,10%,15%.The compaction times include : 5 times,10 times and 15 times.The initial temperature include: 15℃,21℃,25℃.The experimental results show that in the soil heating(cooling)process,the temperature curve can be divided into four periods: pre temperature change period,temperature upheaval period,temperature stabilization period,temperature stability period.And moisture content curve can be divided into two periods: moisture content moisture upheaval period,moisture content moisture stabilization period.In addition,the temperature distribution along the axial direction of 24 h heating(cooling)is fitted by power function,and the correlation coefficient is greater than 0.9 which is a high fitting degree.In the different soil types,the heat and moisture transfer law of gravel sand,coarse sand,silt and clay are close,the law of medium sand and fine sand are close.Compared with other soil samples,the moisture migration of silt and clay are more obvious.With the increase of heat source temperature,the soil temperature influence radius,the time of temperature upheaval period,the temperature of stability period and the amplitude of moisture content curve all increase;a value increases,b value decreases;the phenomenon of soil heat and moisture migration is more obvious.With the decrease of cold source temperature,the soil temperature influence radius,the time of temperature upheaval period,and the amplitude of moisture content curve all increase,the temperature of stability period decrease;the a value decrease,b value increase;the phenomenon of soil heat and moisture migration is more obvious.The effect of initial moisture content on soil moisture and heat transfer is relatively small.With the increase of initial water content,except for the expanding of the soil temperature influence radius;the time of temperature upheaval period,the temperature of stability period,a,b value and the amplitude of moisture content curve all change little.With the decrease of porosity,the soil temperature influence radius,the time of temperature upheaval period and the temperature of stability period all increase;a,b value and the amplitude of moisture content curve all change little.In the heat source condition,with the decrease of initial temperature,the temperature difference between the heat source temperature and the initial temperature expands,the soil temperature influence radius changes little;the time of temperature upheaval period and the temperature of stability period all increase;the temperature of stability period decreases;the a value increases,b value decreases. |
