PFC^3D Mesoscopic Simulation of Self-Boring In-Situ Shear Pressure-Meter Model Test

The self-boring in-situ shear pressure-meter test can obtain the strength and deformation parameters directly through its unique multi-level loading mode; however, the deformation mechanism of the soil surrounding the probe has seldom been studied. To reveal the deformation mechanism of the sand sample surrounding the probe of the self-boring in-situ shear pressure-meter (SBISP) during the loading process, the SBISP model test is simulated by PFC^3D (particle flow code in three dimensions) program in this study. The development of the displacement and stress field of the soil surrounding the probe, as well as the deformation modulus of each grade of the numerical sample and the motion trails of the soil particles, are studied under multi-level loading process. The results of numerical experiments show that the displacement of particles in central area increases with the shear stress imposed stepwise, and the direction of displacement vector shows a clearly preferred direction. Several radial stress cores of approximately symmetrical distribution have formed near both sides of the probe. At the same time, the vertical stress has formed flat stress zones, and it has produced some stress concentration areas in the shoulder of the probe. The motion trails of the particles are step-like lines in the central area which can be divided into three characteristic zones as the distance to the probe increases. The vertical and horizontal displacements of particles descend in a negative exponential form, but the vertical displacement has a faster attenuation rate.