Study On Thermal Properties Of Clay Based On Digital Image Processing Technology

Soil pore parameters are one of the important factors affecting soil thermal properties.The quantity and shape determine soil water retention capacity and soil heat transfer capacity.Due to the complexity and variety of soils,their physical properties are also different.Extremely complicated.Currently limited by measurement technology,the results are often not convincing,so that they do not meet the practical requirements of engineering.The current research on soil thermal conductivity mainly focuses on macroscopic thermodynamic experimental research,revealing the thermodynamic properties of soil from the surface,which can not reveal its intrinsic essential mechanism.Therefore,quantifying the soil mesostructure through experiments can help us to fully understand the internal structure of the soil and lay a foundation for studying the thermal properties of soil.Taking Wuhan typical clay as the research object,a thermal conductivity measurement test and analysis of remolded clay was carried out by using a soil pore quantification system.The soil samples were scanned by CT,and the pore parameters of the samples were analyzed by MATLAB and ImageJ software.Quantify.The following conclusions were obtained:Test part: In the case of a certain dry density,the thermal conductivity of clay increases with the increase of consolidation pressure.When the pressure level is 0-50 kPa,the thermal conductivity increases due to the smaller consolidation pressure.Small(0.34% ~ 0.79%);when the pressure level is 200 ~ 800 kPa,the consolidation pressure is large(0.75% ~ 3.58%),the thermal conductivity of clay increases a lot.When the consolidation pressure is constant,the thermal conductivity of clay increases with the increase of dry density.When the pressure grade is 50 kPa,200kPa,800 kPa,the thermal conductivity increases by 2.34%~10.8%,4.48%~11.26.%,between 4.52% and 12.2%.The reason is that as the pressure level increases,the air between the clay particles is discharged along with the pores,the soil is compacted,the dry density increases,and the porosity decreases.The heat transfer between the soils mainly depends on the solid particles for heat transfer,so the effect of the change of dry density on the thermal conductivity of the clay is significantly higher than the change of the consolidation pressure.Analysis: After quantification of clay by CT scan,MATLAB and ImageJ software,it can be concluded that the change of thermal conductivity of clay is mainly affected by the pore structure of soil: the number of pores,the number of pores of samples with small dry density is small,It shows that the sample area has a small pixel point image ratio,low pixel coverage,high porosity and low thermal conductivity of the clay.The pore area is small,although the dry density is small,the average pore area is relatively Larger,a single pore occupies more pixels,the porosity is still larger,and the thermal conductivity of the clay is lower.It can be found that the influence of the number,area and porosity of the pores in the mesostructure of the clay on its thermal properties is due to the influence of mutual influence and restriction on the thermal conductivity.