## 2 Project Profile  
The Huaipa landslide is located on the mountain to the southeast of the Huaipa Yellow River water-raising project in Chencun Township, Mianchi County, Sanmerxia City, Henan Province, west of Xipo gully, south of the Coal Kiln gully fault and the steep wall of the mountain front to the south, and north of the loess terraces on the banks of the Yellow River. The Huaipa landslide has a length of 550 m from north to south and a width of 450 m from east to west, with a total volume of approximately 400 \(\times\) 104 m\({}^{3}\). The elevation of the trailing edge is 437 m, and the lowest elevation of the leading edge is 295 m (Figure 1). The landslide includes seven small coal and bauxite kilns and shafts, the lower part of which is mostly excavated by mining and is relatively gentle. The large pits formed by mining have resulted in a gentle topography at the leading edge and a slightly steeper topography in the center and rear, with a natural slope angle of approximately 30\({}^{\circ}\). The upper colluvium deposit strata consist of haphazard gravelly soil strata with uneven gravel content, locally high gravel contents, and incorporated rolled stones. The main slip direction of the landslide is approximately 324\({}^{\circ}\), and the gully (Xipo gully) on the west side is \"V\"-shaped in cross-section, with deeper cuts, and the south side of the Coal Kiln gully fault on the upstream side of the gully has been completely blocked by mine slag. On the east side, a shallow gully has developed, with a bottom elevation of 301-350 m.  
Cracks of the Huaipa landslide were mostly 18-106\({}^{\circ}\), with width ranging from 0.5 m to 5.0 m. Most were transverse tensile cracks perpendicular to the main sliding direction.  
At the leading edge of the Huaipa landslide, because of the antisliding effect of the rock strata, the shearing outlet is exposed (Figure 2a), the ground is bulging (Figure 2b), and the top strata of rock and soil is obviously disintegrated, with densely distributed cracks appearing in clusters. In the central part of the Huaipa landslide, there are mainly shearing cracks and first-shear-then-tension cracks in the northeast area, with many soil strips and soil wedges, and the relative displacement on both sides of the cracks is obvious (Figure 2c,d). In the eastern area, there are many large longitudinal cracks, which are first-shear-then-tension and parallel to the direction of sliding, with many soil strips, which are wider at the top and narrower at the bottom (Figure 2e). The trailing edge of the landslide contains mainly tensile cracks, and drunk men woods and bent trees are distributed in this  
Figure 1: Engineering geology plane.  
area (Figure 2f,g). The surface cracks are crisscrossed, with tensile cracking forming a soil lattice and soil wedge; the cracks are wide at the top and narrow at the bottom (Figure 2h) and are distributed in a branching shape.  
The slide zone soil of the Huaipa landslide is fully weathered mudstone and sandstone strata located in the soil-rock contact zone, which is 0.2-0.5 m thick. The Huaipa landslide slide surface is shown in Figure 3. There are many cypress trees growing on the slope, and the stratigraphic lithology is mostly residual slope sediments and fully weathered bedrock, with the inclination angle of the slide zone (bed) ranging from 17.8\({}^{\circ}\) to 52\({}^{\circ}\), mostly around 35\({}^{\circ}\); the thickness of the slide zone is from 13 m to 29 m. The sliding mass is a Quaternary slope colluvial and alluvial gravel soil with bedrock of interbedded anticlinal sandstone and mudstone. A profile of the Huaipa landslide is shown in Figure 4.  
Figure 3: Sliding surface.  
Figure 2: The distribution of cracks.