Compression strength and damage model of frozen silty clay in Xing'an Baikal permafrost under temperature effects

The Daxing'anling, situated within the high-latitude transition zone between continuous and sporadic permafrost, mark the southern boundary of the Northern Hemisphere's permafrost distribution. The thermally sensitive Xing'an Baikal permafrost in this region was investigated through uniaxial compression tests on remolded silty clay under controlled freezing temperatures (- 7.5 to - 0.5 °C). Results revealed a triphasic strength-temperature relationship: strength increased at 79.99 kPa/°C between - 0.5 and - 2.0 °C, surged to 1842.00 kPa/°C from - 2.0 to - 3.0 °C, then declined to 316.20 kPa/°C below - 3.0 °C. A brittle-ductile transition occurred at - 3.0 °C, shifting failure modes from plastic to brittle deformation. Building on Lemaitre's strain equivalence principle and Weibull statistics, we developed a dual-variable damage model integrating thermal and mechanical damage, enabling quantitative cryogenic damage assessment, coupled damage evolution equations, and full temperature-regime stress-strain predictions. This work advances theoretical tools for engineering stability evaluation in the Xing'an Baikal permafrost environments.