Abstract
With the increase in rainfall, landslides occur on many gentle slopes in the mountainous areas of southeast China. Gentle slopes have a particular dual geological structure, i.e., the lower part is a gravel soil layer with good water permeability, and the surface layer is clay soil with relatively poor water permeability. Under conditions of heavy rainfall, a gentle slope with this structure is likely to collect temporary confined water. The intermittent creep of the upper slope is caused by the floating force of the temporary confined water, which causes landslide disasters. The conditions that bring about temporary confined water are related not only to the stratum structure, but also to the rainfall intensity and the initial height of the water table level. On the basis of the characteristics of the stratum of the gentle slope landslide on the front of Fanshantou Mountain, we constructed a hydrological model in GEO-STUDIO. We investigated the effect of different rainfall intensities and initial water table levels on confined water under continuous rainfall conditions and conducted a corresponding stability analysis. The results show that when both the initial water table level and the rainfall intensity are high, temporary confined water is formed rapidly, increasing the chance of a landslide disaster. The research results provide a theoretical basis for the treatment of landslides on similar gentle slopes in the mountainous areas of southeast China.
Highlights
The results show that the Fanshantou landslide has typical stratigraphic features that are favorable to the formation of confined water, i.e., the upper part of the mountain is steep with a gravel soil layer; the middle and lower parts are widely covered with loose Quaternary sediments, which form a gentle slope on front of the mountain
It is generally believed that a gentle slope on the front of a mountain is equivalent to a loading berm, which is beneficial to the stability of the slope
It was found that this gentle slope has a special geological structure, i.e., the surface layer is impermeable clay soil, and the lower layer is gravel soil, which is conducive to the accumulation and occurrence of groundwater
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The results show that the Fanshantou landslide has typical stratigraphic features that are favorable to the formation of confined water, i.e., the upper part of the mountain is steep with a gravel soil layer; the middle and lower parts are widely covered with loose Quaternary sediments, which form a gentle slope on front of the mountain. The upward floating force generated by the temporary confined water causes the creep displacement of the upper slope body, and landslides occur. This type of confined water only exists when rainfall occurs and is related to the rainfall intensity and initial groundwater table level. The influences of different rainfall conditions and different initial groundwater table levels on accumulation landslides are analyzed using a numerical simulation
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