# Factors Affecting the Stability of Loess Landslides: A Review
## 3 Comprehensive Analysis of Loess Landslides
### Analytical Factors  
Collapsibility is an important characteristic that distinguishes loess from other soil types, and it is this characteristic that distinguishes loess landslides from rock landslides and normal soil landslides. Under a certain pressure, the soil structure is quickly damaged and characterized by subsidence because it is wetted by water. The stability of various parameters is therefore significantly affected by this property. Not all types of loess are collapsible. The thickness of collapsible loess is not great. It is usually about 10-15 m in the upper part. Its specific granular framework structure determines the collapsibility of loesses [27]. At the peak of the collapsibility coefficient, the structural weakening induced by water saturation reaches its maximum [98]. The collapsibility of loess samples can be visualized under a scanning electron microscope. It is a macroscopic manifestation resulting from changes in intergranular cementation. In addition, continued wetting also causes the fracture to widen further [96]. In the humidification test, the softening effect of water exceeds its fracturing effect on the soil, especially when the water content is high [97]. The inherent structural strength of loesses and the external pressure applied strongly influence the deformation damage characteristics of loesses caused by the humidification process [89]. The main blocky nature of sand particles and the flaky nature of silt particles are shown in Figure 7. Flaky particles have flat surfaces with clean edges and irregular fractures. Bulk particles have rough surfaces, uneven edges, and jagged fractures. Lamellar particles are \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Analytical Factors** & **Measured Parameters** & **Methods** & **Application** & **References** \\ \hline \multirow{6}{*}{\begin{tabular}{c} pore water pressure \\ \end{tabular} } & \multirow{3}{*}{\begin{tabular}{c} tensile cracks, volumetric \\ moisture content, matric suction \\ \end{tabular} } & model test, early warning & \multirow{3}{*}{\begin{tabular}{c} survey and monitor \\ (loess) \\ \end{tabular} } & \multirow{3}{*}{[29; 30]} \\  & & threshold model, field & \\  & tensile cracks, volumetric & experiments, numerical & & \\  & moisture content, matric suction & simulation, soil moisture & & \\  & sensors, tensiometers, & & \\  & & earth pressure cells & & \\ \cline{2-5}  & shear strength & shear tests & \begin{tabular}{c} survey \\ (non-loess) \\ \end{tabular} & [13] \\ \hline \multirow{6}{*}{\begin{tabular}{c} creep \\ \end{tabular} } & \multirow{3}{*}{\begin{tabular}{c} long term strength, peak \\ strength, moisture content, \\ stratum lithology, rainfall \\ \end{tabular} } & creep model tests, triaxial & \multirow{3}{*}{\
\begin{tabular}{c} survey \\ (loess) \\ \end{tabular} } & \multirow{3}{*}{[14; 91; 97]} \\  & & creep tests, steady-state & \\  & & creep rate slope & & \\  & method (SCRSM) & & \\ \cline{1-1} \cline{2-5}  & line-of-sight & hot spot analysis, optical &
\begin{tabular}{c} survey and monitor \\ (non-loess) \\ \end{tabular} & [26] \\ \cline{1-1} \cline{2-5}  & deformation velocity & satellite image analysis & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._mainly horizontally stacked. Only a few are found in the spacing or intergranular pores formed by both particle types. Furthermore, silt particles are observed enveloped in clay sheets. The clay particles fill the interstitial and intergranular pores and bind the sand and silt together to strengthen the particle bonds and form the overall structure [96]. It is therefore clear that both internal and external factors are involved in causing loesses to collapse. The interaction between loess collapsibility and water is vividly illustrated under microscopic conditions. Experimental data suggest that loess collapsibility correlates with water content. Loess landslide parameters (e.g., fractures, volume, resistivity, shear, water content, etc.)