Numerical Simulation of Geogrid-reinforced Flexible Support for Treating Expansive Soil Cut Slopes

The influence of various interface strength parameters, different reinforcement spacing, and types of slope (enveloped or not) with a geogrid on flexible-support-reinforced expansive soil cut slopes was investigated by numerical simulation. The simulation considered the attenuation of the shear strength of expansive soil due to rainfall, evaporation, and other long-term atmospheric weathering actions in combination with shear strength parameters determined by a laboratory-measured expansive soil nonlinear strength envelope. Results showed that the geogrid can effectively restrain horizontal slope displacement and decrease the soil expansion softening effect to a certain extent, such that the sliding surface of the slope became deep. The change in maximum axial force was small due to a change in interface strength parameters between the geogrid and soil, but the safety factor increased with the increase in maximum axial force. The changes in maximum axial force along the height for different geogrid reinforcement spacing values were basically similar; the values increased initially and then decreased. Small reinforcement spacing equated to a small maximum value. The stability of the expansive soil slope was significantly influenced by reinforcement spacing; small spacing meant good slope stability. The enveloped geogrid indirectly improved the safety, resistance to erosion, and integrity of the slope.