Thermal And Electrical Characteristics Of Sand In Salt Solution Environment

The subsurface freshwater resources of the island,which are endowed inside the coral reef and float above the seawater,are important resources to maintain the life and ecosystem of island plants and animals.Coral reef sand with special biological genesis,irregular morphology,rich in pores and endopores,adsorbs different salt ions,and intergranular pore water also has high salinity.The process of salt ion removal by reef sand adsorption and freshwater replacement by intergranular saline pore water are important factors that influence and restrict the process of groundwater desalination.The paper presents the corresponding relational equations and prediction models to characterize the dynamic changes of moisture and salinity and evaluate the state of groundwater desalination in the island by testing and analyzing the thermophysical and electrical properties of sandy soil under different water content and salinity solutions.A new idea of predicting groundwater desalination process based on thermal and electrical parameters is provided.The main research contents and results are as follows:1、Based on the tests of thermal conductivity,volumetric specific heat capacity and thermal diffusion coefficient of coral fine sand in South China Sea islands under different dry density and water content,12 sand and soil thermophysical parameter models are compared,and an empirical model of coral fine sand thermal conductivity with suitable and higher prediction accuracy is proposed,which lays a theoretical foundation for the analysis of sand and soil thermal performance under salt solution environment.2、The results show that there is a negative correlation between salt solution concentration and geotechnical thermophysical parameters,and there is a correlation between thermophysical parameters and geotechnical medium and particle morphology,and the coupling of the two factors affects the thermophysical parameters of marine medium and terrestrial medium to The degree of influence of the coupling of the two factors on the thermal and physical parameters of the marine and terrestrial media varies.The prediction model of thermal conductivity of sandy soil in salt solution environment is proposed to realize the rapid characterization of thermal and physical parameters of sandy soil in the process of water-salt transport.3、Based on the obvious differences in the thermal characteristics of the marine medium and the terrestrial medium,the interrelationships and differences between the volumetric conductivity of the sandy soil and the water content,salt content and grain size are analyzed by comparing the electrical indexes of the sandy soil under different water content and salt content conditions.The results show that the volumetric conductivity of sandy soil gradually increases with increasing water content under the determined salinity conditions,and the volumetric conductivity of coarse sand is larger than that of medium sand and fine sand due to its larger pore space and connectivity;under the same water content,the volumetric conductivity of sandy soil gradually increases with increasing salinity,and the higher the salinity of sandy soil,the more significant the effect of increasing water content on volumetric conductivity;the estimated conductivity of sandy soil is derived The equation for estimating the conductivity of sandy soil was derived,which provides a reference for evaluating the desalination state of groundwater and analyzing the salinization degree of sandy soil.