Influences of Pore-Water Pressure on Slope Stability considering Strength Nonlinearity

The pore-water pressure is a vital factor in determining the slope stability. To deal with the stability of slopes undergoing pore-water pressures, this paper used the pore-water pressure coefficient to develop the three-dimensional limit analysis method for slope stability evaluation with a nonlinear strength envelope. For numerical slope examples, the critical heights and corresponding critical slip surfaces associated with linear and nonlinear envelopes were derived by using a numerical optimization procedure. The influences of pore-water pressures on the slope stability were addressed by comparing the upper-bound solutions derived by linear and nonlinear strength envelopes (the linear and nonlinear results for short). The obtained two critical inclinations between the linear and nonlinear results both decrease and gradually approach with increasing pore-water pressure coefficient. For most slopes subjected to pore-water pressures, using the linear Mohr–Coulomb envelope will obviously overestimate the slope critical height. The overestimation resulted from the linear criterion will become more distinct for slopes with smaller widths. Besides, the presented results showed that the equivalent internal friction angle tends to have a weaker increasing trend for steeper slopes as pore-water pressure coefficient increases. Hence, when pore-water pressure coefficient increases, the critical slip surfaces of gentle slopes with nonlinear strength criteria become shallower, but the critical slip surfaces of steep slopes seem to have no consistent change law. These results and analyses can illustrate the significance of the application of nonlinear strength envelopes in slope stability evaluation considering pore-water pressures and provide certain reference advice in slope engineering design and landslide prevention