In-situ direct shear test and numerical comparative research on mudstone gravel slope reinforced by polymer grouting

This study investigates the shear strength characteristics of mudstone gravel slope following polymer grouting reinforcement through in-situ direct shear test. A corresponding numerical model was developed to analyze stress distribution. The findings indicate that shear stress initially increases and then stabilizes with horizontal displacement during the pre-grouting shear test. Post-grouting, a distinct stress peak emerges on the stress-displacement curve, signifying a substantial enhancement in overall shear strength. The peak shifts with increasing vertical stress, delaying the onset of yield strength. Moreover, a direct correlation exists between shear strength and the density of grout injected. Numerical simulations reveal an H-shaped stress distribution around the shear plane. Upon severing the grouting column, the stress distribution becomes intricate, with stress appearing to circumvent the column. The discrepancy between simulation and experimental data is minimal, with the simulated internal friction angle deviating by -0.97-1.5% from the experimental values and the simulated cohesion being marginally lower, with an error range of 3.9-5%. These results offer valuable insights for engineering applications.