Influence of intrusive granite dyke on rainfall-induced soil slope failure

Intrusive granite dykes and their weathered layers can have great effects on seepage into slopes and on their stability. However, few studies of this topic have been reported. Using the Zhonglincun landslide as an example, we investigate the impact of a dyke and its weathered layer on the formation mechanism of a rainfall-induced residual soil slope failure. The sliding mass of Zhonglincun landslide is mainly composed of residual soils of both tuff and an intrusive granite dyke. We used laboratory soil column tests to obtain rainfall infiltration characteristics of the two residual soils. The SEEP/W mode of Geo-studio software was then used to replicate the above soil column tests to back-analyze unsaturated hydraulic parameters of the two soils, which were later used to simulate seepage fields and stress-strain fields of the slope under Typhoon Tailim. The results indicate that the movement of rainwater in the residual soil of the granite dyke is much faster than that of the residual soil of the tuff. Rainwater infiltrates rapidly into the granite soil, and then flows laterally into the tuff residual soil, raising the groundwater table in the slope, especially near the contact between the two residual soils. This leads to a rapid increase in pore-water pressure and initiates the serious deformation of the landslide. The granite dyke and its residual soil have played a key role in the formation of Zhonglincun landslide.