Study on Multi-stage Static Compaction Deformation and Prediction Model of Coarse-grained Soil in Western Mountainous Regions

In order to reveal the compaction characteristics of accumulation slopes in mountainous areas of western China, multi-level static-loading orthogonal tests were used to analyze the effects of overlying load, fine-grained content, and water content on the compaction deformation of coarse-grained soils from high-altitude accumulation slopes. The results showed that: ① the specimen under a single-level overlying load experienced four deformation stages, namely rapid, fast, slow, and stable settlement. Under multi-level static loads, the settlement deformation of the specimen exhibited a continuous stepped pattern. For the first-stage load, both the stage settlement and deformation rate were the largest, followed by a stage-by-stage nonlinear attenuation trend. ② The dry density of the specimen increased rapidly first and then slowly with increasing load, and the amplitude of increase under the first-stage loading was as high as 8.6%. Water content had a nonlinear promoting influence on the dry density of soil specimens, while fine-grained content showed an attenuating influence, with the latter being stronger. ③ Based on compaction theory and experimental observations, a multi- parameter density prediction model for coarse-grained soil considering the influences of overlying load, water content, and fine-grained content was established. The good applicability of the theoretical model was verified by experimental values. These studies will provide a theoretical basis for the scientific prevention of accumulative layer disasters in the western region and the quality control of coarse-grained filling engineering.