Existing methodologies for calculating frictional resistance are often inadequate in capturing the strain softening effect in clay and rate effect at interfaces by Abaqus/Explicit accurately. A contact algorithm by subroutine is developed to enhance the structure-clay interaction model to overcome these limitations. Based on the Coulomb friction law, the relevant parameters are captured and used to the Coulomb’s friction coefficient calculation by the subroutine. The reliability of simulation results is corroborated using a novel ring shear model. A one to two orders of magnitude in-crease in shear velocity leads to a 1.36 to 1.85-fold increase of frictional resistance by the rate effect. When the rate effect is integrated into the strain softening process, the clay within the shear band experiences a degradation of strength. The shear rate is inversely related to the degradation time. A reduction of the ultimate frictional resistance to between 45% and 50% of its peak value. The ultimate frictional resistance does not descend to the theoretical mini-mum due to the incomplete degradation of soil within the shear band.