## 5 Three-Dimensional Numerical Simulations of the Huaipa Landslide
### Landslide Creep Deformation and Disaster Evolution Mechanism  
To simulate the catastrophic creeping process of the Huaipa landslide under excavation and rainfall, a three-dimensional geological model of the landslide was established according to the field investigation and engineering geological survey, as shown in Figure 13. In \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Moisture** & **Bulk Modulus** & **Cohesion** & **Friction** & **Kelvin Shear** & **Kelvin** & **Maxwell** & **Maxwell** \\
**Condition** & **(lrPa)** & **(lrPa)** & **(\({}^{\circ}\))** & **Modulus** & **Viscosity** & **Modulus** & **Viscosity** \\
**Natural** & \(1.38\times 10^{5}\) & \(0.094\times 10^{3}\) & 23 & \(8.44\times 10^{3}\) & \(7.2\times 10^{5}\) & \(0.24\)-\(0.7\times 10^{4}\) & \(1.728\times 10^{9}\) \\
**Saturated** & \(1.03\times 10^{5}\) & \(0.021\times 10^{3}\) & 24 & \(8.84\times 10^{3}\) & \(9.61\times 10^{4}\) & \(0.09\)-\(0.53\times 10^{4}\) & \(4.69\times 10^{8}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Parameters determined using simulations of the triaxial creep tests. Figure 12: Fitting curves under a confining pressure of 300 kPa. (**a**) Saturated state, (**b**) Natural state. the calculation process, the elastic-plastic model was first used to analyze the deformation characteristics of the slope after the excavation of bauxite at the front edge of the slope in March 2013. The Burgers-Mohr model was used for the sliding zone to calculate the creep deformation of the slope under the condition of natural water content until April 2014. The creep deformation of the slope under the condition of sliding zone saturation caused by rainfall was then calculated until 2 May 2014. The calculated parameters are shown in Table 7.  
Figure 14 shows the deformation evolution process of the slope from the natural state to the saturated state, as a result of the excavation of bauxite at the front edge and rainfall. The results demonstrate that the excavation of the bauxite mine at the leading edge of the slope in March 2013 destroyed the support at the slope foot. This caused unloading and produced large bulge deformation at the slope foot; however, the slope did not experience significant overall sliding at that time. Owing to the creep characteristics of the sliding zone in the natural state, the trailing edge of the slope was later damaged by tension and the slope foot sheared out. The deformation of the middle and rear of the slope increased significantly, with a maximum slope displacement of 15 cm over the 390 days prior to April 2014. Continuous rainfall in April 2014 caused the sliding zone to become saturated, and the slope deformation began to significantly accelerate. By 2 May 2014, the 422-day maximum displacement reached 21 cm. Finally, the slope began to slide as a whole and the large-area landslide occurred. According to the landslide body displacement deformation, the landslide can be divided into a front edge bulging zone (anti-slide section), a central sliding zone (main slide section), and a trailing edge tension zone. The simulation results are fully consistent with the field geological survey analysis shown in Figure 3.