Study on internal erosion and structural evolution mechanism of soil–rock mixture

In mountainous areas, soil–rock mixture (SRM) is very prevalent and is frequently used to fill embankments. The safety of people's lives and property, however, is seriously threatened by the seepage characteristics of SRM, which frequently result in diseases such as uneven settlement and subgrade instability. This paper used a combination of experimental and numerical methods to study the particle erosion characteristics and structural evolution mechanism on SRM under seepage. It was based on the three-dimensional particle flow code (PFC3D) and computational fluid dynamics (CFD) theory. The findings demonstrate that migration velocity fluctuations on SRM particles with different particle sizes have different amplitudes and frequencies. The essence of the variation in SRM stability and mechanical properties, on the other hand, is the variation in porosity and gradation composition of fillers in different parts as a result of particle migration. Additionally, the soil–rock interface has a significant impact on the structural evolution characteristics of SRM. The number of contacts between particles under seepage erosion decreases over time, with a decreasing range of 8.73%. However, the contact force value exhibits an upward trend, and the model's bottom was where the contact force abruptly changed to its top value. Initial failure, erosion, and relative stability stages make up the SRM erosion failure mode of the seepage simulation. Due to the interlocking effect between them, the rocks do not move around much, and the fine particles cause the filler skeleton to move from the bottom to the top, which has an impact on the overall stability and mechanical characteristics of SRM. This study will significantly advance the creation and use of SRM materials that perform well on roads, bringing about significant engineering and financial gains for the building sector.