Model tests on landslide dam materials improved by dynamic compaction

In order to enrich the development and utilization theories of landslide dams and guide the shallow compaction reinforcement projects, based on the similarity law, the dynamic compaction model tests on landslide dam materials with different energy levels are carried out, and the development and propagation law of dynamic stress caused by dynamic compaction energy, the displacement characteristics as well as the particle breakage and reinforcement effects are analyzed by using the macro-meso-method. The test results show that with the increasing tamping times, the peak value of dynamic pressure within the effective reinforcement range of the rammer exhibits a fluctuating upward trend as a whole due to the increasing compactness of landslide dam materials and the superposition effects of particle breakage, rearrangement and filling. During the process of dynamic compaction, the energy is transferred from the surface one to the deep layer gradually. Meanwhile, the energy dissipates greatly with the depth, and the peak value of dynamic stress decreases rapidly with the depth. Due to severe weathering, obvious particle breakage is caused by the dynamic compaction. The reinforcement effects of the dynamic compaction is obvious for loose- and wide-graded landslide dam materials. The cone tip resistance of the dynamic compaction with different energy levels greatly increases, but the reinforcement effects are limited by increasing the tamping energy when it exceeds a certain value. Based on the model tests on the Yigong landslide dam materials, the best tamping energy is about 6000 kN·m.