Model for increment of static earth pressure of unsaturated silty clay under wetting conditions

In excavation and retaining wall engineering, wetting of unsaturated soil can result in significant increment of lateral soil pressure and even structural damage. To assess this effect, the tests with different initial saturation degrees and varying overburden loads are conducted, and the relevant model is established. The results show that: (1) After wetting saturation, the static soil pressure coefficient K₀ remains constant and is not affected by the initial saturation degree or overburden load. (2) The samples with lower initial saturation degrees exhibit greater increment in static soil pressure after wetting saturation. (3) The increment of the static soil pressure after wetting saturation increases with higher overburden loads. (4) Based on the experimental data and mechanical analysis, a bilinear model considering the overburden load and initial saturation degree under wetting conditions is established. The model shows that the wetting soil pressure can exceed the initial soil pressure by over 1.8 times and emphasizes the need to consider wetting in design.