Water-rock /soil interaction reflected by the chemical characteristics of groundwater of Jichang landslide in Guizhou Province

The water-rock/soil interaction of a landslide is a complex physical and chemical synthesis, which seriously affects the stability of the slope. Research on the water-rock/soil interaction of a landslide on the occurrence of geological disasters is relatively weak. This article takes the Jichang landslide as the research object, analyzes the characteristics of the mineral composition and chemical composition of the rock and soil in the landslide area, combines the compositional changes of bedrock fissure water and atmospheric precipitation in the area, and uses the principal component analysis method to study the water-rock of the Jichang landslide The process of action and the influence of water and rock evolution on the stability of landslides are analyzed. The results show that: (1) The weathering process of basalt in the sliding body is a water-rock interaction coupled by mechanical crushing-mineral alteration, occurring on “micro-micro-macro” three scales. (2) The first three factors, accounting for 49.365%, 27.135%, and 15.092% of the total variance, respectively, are selected to analyze the chemical characteristics of groundwater. The main factor Z₁ reflects the control effect of the dissolution of basalt primary minerals on the chemical composition of the groundwater, the main factor Z₂ reflects the evaporation of groundwater and the precipitation of minerals in which the solubility of SiO₂ changes with pH, and the main factor Z₃ reflects the ion exchange between groundwater and rock (soil) with the main participating ions being Mg²⁺ and K⁺. (3) The products of water-rock interaction are mainly clay minerals such as illite, smectite and chlorite, which increase the content of clay minerals in the structural plane of the rock mass, deteriorate and damage the rock mass, significantly influcing the formation of slip zones and the disintegration of landslides. The results of principal component analysis of groundwater can reflect the main process of interaction between landslide groundwater and rock/soil.