Methods for determining shear resistance by a system of cracks and old slip surfaces with the purpose to evaluate the stability of landslides

Abstract

On slopes, landslide displacements mainly occur along bedding boundaries, lithogenetic and tectonic fractures, as well as along existing ancient slip surfaces, which are the weak zones and potential slip surfaces for new landslides. According to experimental studies to determine the shear resistance by the standard and double cut test methods: a) without wetting the sliding surface, and b) by the wetting the sliding surface, we can conclude: when double- cutting the clay soils of a solid, semi-solid and tightplastic consistency, the cohesion is mainly reduced, but the internal friction factor is slightly changed. Double-cut tests of soft-plastic and flow-plastic clay soils have shown the cohesion and the internal friction factors are being changed insignificantly. At the same time, taking into account the fact that under the condition τ > σ tan ϕ the soft-plastic and flowing-plastic clay soils undergo viscous-plastic deformations, we come to the following conclusion. When developing the anti-landslide measures, independent of the consistency of the soils forming the slope, the τf = σ tan ϕ component should be taken as the slip resistance index in the formula for calculating the slip resistance taking into account the condition Cc + Σw = 0.