Laboratory Investigation on Thermal Conductivity of Geotextile- Reinforced Soils

Abstract

The design of thermally active ground structures such as energy geo-structures and shallow and deep geothermal systems requires knowledge of the thermally geological properties of soils and rocks. Soil thermal conductivity is a critical parameter of geological formation for designing geothermal energy foundations. This paper presents the results of thermal conductivity of soil reinforced with geotextile layers with transient method (needle probe test). Effects of different volumes of soil, sand granulation, geotextiles positions and numbers in soil, various densities, and water contents on thermal conductivity were investigated in detail. The results demonstrated that the thermal conductivity varies with the water content, soil density, different granulation, the number of geotextile layers and their positions in the test cylindrical container, and soil volume. It has been found that thermal conductivity with one geotextile layer at 1/3 of the container bottom with coarse-grained soil at the top and fine-grained at the bottom is minimum. In addition, coarser-grained soils encapsulated between geotextile layers have lower thermal conductivity than the similar case when fine-grained soils are used. Moreover, by increasing the soil mass density and decreasing the void ratio, the thermal conductivity of the soil increases.