Thermal effects on the shear behaviour of saturated coarse-grained soils with reference to post-earthquake deposits

Recently, the dependency of post-earthquake landslides on temperature variation has been increasingly discovered, where the slope deposits at risk are often enriched with loose and nearly saturated coarse soils, i.e., landslides after 2008 Wenchuan earthquake. To reveal the thermal effects on the shear behaviour of such materials, a series of temperature-controlled triaxial tests were carried out on soils obtained from post-earthquake deposits. Various temperature conditions were investigated, including temperature level and heating–cooling cycles. It is found that shear strength is slightly increased with rising temperature. At low confining pressure, the gain in strength mainly comes from the enhanced interlock among particles due to thermal expansion, while the thermal densification at soil skeleton level also contributes to strength increase at high confining pressure. Moreover, the contractive strain accumulates as heating–cooling cycles progress, which results in an increasing shear strength. Under a low confining pressure, both expansion during heating and contraction during cooling were minor and reversible. With high confining pressure, the volumetric strain during thermal cycles is significantly increased (up to one order of magnitude) compared to results of other coarse soils in the literature, which indicates that the influence of grain size on thermal deformation cannot be neglected.