Immersion test on the mixed sliding zone soil in tuff formation considering environmental factors in evolution process

Tuff formations are widely distributed, and the contact zone between shallow weathered tuff and overlying cohesive soil is prone to forming sliding zone. The development of shallow sliding zones in tuff strata involves the combined effects of multi-dimensional environmental factors, e.g., mixing of different soil components, changes in sand content due to rock weathering and seepage, pre-rainfall moisture conditions, immersion depth of surface runoff, and seasonal water temperature variations. To elucidate the roles of these factors in the formation and evolution of sliding zones, immersion tests were conducted to investigate the disintegration characteristics of completely weathered tuff-silty clay mixtures under various environmental conditions. The experimental results demonstrate that: An increase in sand content accelerates the disintegration progress of mixed soil during immersion. Drier initial conditions lead to significantly faster disintegration compared to pre-wetted or fully saturated soils. The influence of immersion depth on disintegration behavior depends on soil composition. Elevated water temperature markedly enhances the disintegration rate of mixed soils, though seasonal temperature variations show negligible effects on pure completely weathered tuff. The impact of environmental factors on the aqueous disintegration of mixed soils correlates with their microstructural characteristics.