Abstract
The present study used PFC numerical software to examine the mechanical properties and fracture propagation characteristics of the fractured rock mass under coupling of heavy rainfall infiltration and mining unloading. Based on the engineering background of the Dexing mine, the pore water pressure is set to 0, 0.5, 1.0, 1.5, and 2.0 mpa, the true triaxial lateral unloading rate is 0.3 mpa/level and 0.6 mpa/level, and the water content state of rock is dry, natural, and saturated. Then, the true triaxial compression numerical simulation test is carried out, and the results showed that with the increase of the water content, the rock compaction stage increases, the elastic stage shortens, and the yield stage becomes more obvious. The faster the unloading rate is, the greater the influence on the rock strain is. After unloading, the stress jump point appears and the strain increase rate becomes larger, the volume of the rock increases and occurs as large s in the unloading direction, and finally it leads to severe brittle failure of the rock. With the increase of rock pore water pressure, the compressive strength and the peak strain of the rock decrease, and the pore water pressure accelerates the process of rock failure.
Highlights
Since the 21st century, with the rapid development of modern mine technology, the scale and depth of mine rock mass projects have been continuing to grow rapidly
4.1.1 Fractured Rock Mass Model The size of the true triaxial simulation specimen is 70 mm × 70 mm × 70 mm cube, and the parallel bond model is usually used when particle flow code (PFC) simulates the high bond strength and the bending moment load of rock, while the plane joint model is used in the meso-structural plane (Shi et al, 2018)
Three sets of initial stress levels (σ1 and σ3 take three sets of values, that is, three drill-hole sampling points) are selected according to a representative set of pore water pressure measured in site and the distribution characteristics of typical fractured rock mass, under the condition that the specimen is saturated with water, the pore water pressure and the initial fracture distribution of the specimen are certain, and the unloading stress is adopted by plan A and plan B
Summary
Since the 21st century, with the rapid development of modern mine technology, the scale and depth of mine rock mass projects have been continuing to grow rapidly. Mechanical excavation, and weathering, a large number of secondary fissures have been generated inside the high-steep rock slope, which further aggravates the fracture and instability of the rock mass In this area, the geological disasters induced by heavy rainfall are becoming more and more serious In-depth analysis of the mechanical properties and crack propagation characteristics of the fractured rock mass of high and steep rock slopes was carried out under the coupling of heavy rainfall infiltration and mining unloading. It can provide necessary theoretical support for open-pit slope mining and underground surrounding rock support
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