Shear strength attenuation law and mechanism of gravel-soil under immersion

After a reservoir is filled with water, the gravel-soil of a slope is immersed, and the mechanical properties are changed, which affects the stability of the slope. To investigate the influence of immersion on the mechanical properties of gravel-soil, the gravel-soil at the back edge of the slope that has not been immersed was used and large-scale direct shear tests were performed to obtain the shear mechanical properties of gravel-soil after different immersion days. The test results show that after 40 days of immersion, the cohesion of gravel-soil decreases by 39% and the internal friction angle decreases by 8.3%; the cohesion of gravel-soil decreases significantly in the initial stage of immersion and the decay rate decreases with the increasing number of days of immersion.After 20 days of immersion, the cohesion does not decrease significantly with the increase of immersion days. To reveal the reason and mechanisms of shear reduction in gravel-soil, triaxial shear tests, laser particle size analysis and l