Nonlinear degradation of stability of Q2 loess slopes in northern Shaanxi considering rainfall conditions

Abstract

Objective Rainfall disasters are one of the most common disasters on loess slopes in northern Shaanxi, and revealing the effects of rainfall on loess slope stability is beneficial for preventing and controlling such disasters. Methods This research studied the mechanical properties of Q2 loess in northern Shaanxi under rainfall conditions through a series of tests. Combined with numerical simulation technology, the influence of these changes on the stability of loess slopes in northern Shaanxi was analyzed.Firstly, the drying-wetting cycles test (cyclic path and the number of cycles) was designed to simulate rainfall conditions (such as intensity, frequency, etc.).Secondly, a triaxial shear test was performed to obtain the variation law of the mechanical properties of the Q2 loess in northern Shaanxi.Finally, taking a loess slope in northern Shaanxi region as an example, finite element calculations were carried out, by which the change characteristics of the slope safety coefficients and plasticity zones under different rainfall conditions were analyzed. Results The results show that (1) the shear strength of Q2 loess after the action of drying-wetting cycles has nonlinear deterioration characteristics. When the number of drying-wetting cycles exceeds a specific range, the marginal effect of the deterioration of the physical and mechanical property parameters of loess is weakened and tends to stabilize. (2) The stability of loess slopes decreases under the effect of rainfall, and it decreases with the increase of rainfall frequency or intensity. (3) The plastic zone of Q2 loess slopes in northern Shaanxi increases with the continuous deterioration of the mechanical properties of the Q2 loess, which reveals a nonlinear characteristic of the influence of rainfall on the stability of the loess slopes. Conclusion The research results can provide a reference for preventing rainfall-induced landslide.

Keywords

• rainfall condition
• q2 loess
• drying-wetting cycles effect
• shear strength
• safety factor
• loess slope
• nonlinear degradation
• northern shaanxi