Abstract: The strength properties of deep clay are crucial for developing deep strata. However, the direct shear test remains a preferred method for determining the engineering strength of deep clay due to challenges with triaxial tests under high pressure, which can be time-consuming and prone to failure. Whether the upper limit of shear rate in the slow direct shear test and the shear rate range in the consolidation quick direct shear test recommended by national codes are suitable for deep clay with very low permeability needs further study. Using a constitutive model that accounts for anisotropic effects, a seepage-stress coupling numerical model of the direct shear test was developed, and it was validated by the consistency between numerical and experimental results of deep clay in East China. Based on this model, direct shear tests were simulated for clay under three different consolidation pressures and three shear rates. The results show that due to the nonlinear pore pressure variations within the shearing band with shear rate and consolidation pressure, the shear stress at failure decreases nonlinearly with increasing shear rate, and the decrease is more pronounced with higher consolidation pressure. For the simulated remolded deep clay with a permeability coefficient around 10^-12 m·s^-1, the internal friction angle from simulations at 0.5 times the upper limit shear rate is close to the one obtained from undrained triaxial shear tests. In contrast, using the recommended shear rate for consolidation quick direct shear tests results significantly underestimated internal friction angle.