Abstract:

With the development of geomechanics and the requirements of many large-scale engineering projects, especially in road, water conservancy, etc., the soil and rock aggregate mixture has been regarded as a special type of soil and rock material which attracts more and more attention for geotechnical engineers. Based on three dimensional particle flow code PFC3D, the direct shear test model of soil and rock aggregate mixture is established; and the simulation with different rock contents and different rock properties is carried out. According to the simulation results, the rock content and properties control the shear strength to a large extent. The friction angle of hard soil and rock aggregate mixture is 6°-7°larger than that of soft soil and rock aggregate mixture; and the largest friction angle occurs under about 60%-80% rock content. The shear surface of soil and rock aggregate mixture is no longer a flat surface; and the surface band increases with the increase of rock content. In the shear process, the soft rock mixture exhibits dilatancy under low normal stress, shear contraction under high normal stress and strain softening; while the hard rock mixture displays dilatancy and plasticity. The energies are mainly kinetic energy and strain energy for soft rock mixture; while the energies are mainly friction energy and kinetic energy for hard rock mixture.

Key words: soil and rock aggregate mixture, particle flow code, mesomechanics, direct shear test, shear surface