Numerical study on micro-reinforcement mechanism and environmental control of gravel soil under dynamic compaction

This paper focused on the reinforcement mechanism of gravel soil under dynamic compaction and the impact of vibration on the environment from a microscopic perspective. Based on the in-site dynamic compaction test data of Guiyang Longdong Airport, China, and the theory of discrete element method, numerical models were built by the two-dimensional discrete element program PFC 2D to simulate the impact loading process of dynamic compaction. The fabric change of gravel soil before and after dynamic compaction and the effect of vibration isolation trench on the stress and deformation of soil were studied from the microscopic point of view. The results show that the coordination number of soil particles increased and the porosity decreased; thus, the gravel soil was compacted under dynamic compaction. The changes of contact forces generated by dynamic compaction firstly appeared in the soil under the tamper and gradually spread out in all directions, and finally formed a particle force network in a certain area. The vibration isolation trench can effectively reduce the stress level and ground deformation of gravel soil caused by dynamic compaction. However, there was a critical depth, beyond which the isolation effect was weakened. The findings in this work provide a new idea for the study of the micro-reinforcement mechanism of gravel soil and vibration prevention measures by dynamic compaction.