This document discusses methods for improving soil properties through temperature control, including heating and freezing the ground. It describes how the thermal conductivity, heat capacity, and latent heat of soils are affected by temperature. Heating soil can increase its strength and durability by decreasing compressibility and increasing cohesion, internal friction angle, and elasticity. Specific applications of in situ thermal stabilization include landslide prevention, improving collapsible soils, building mat foundations, and reducing lateral pressures on retaining walls.