No abstract

Purpose It is well-known that consolidation rate of prefabricated vertical drain (PVD)-installed ground is closely related to the discharge capacity of PVD, which decreases with an increase in effective stress. This paper aims to present consolidation behaviors of PVD-improved ground considering a varied discharge capacity of PVD. Design/methodology/approach A simple equivalent vertical hydraulic conductivity (k′ve method) was proposed in plane strain numerical analysis, in which the effect of decreased discharge capacity with depth was considered. Numerical analysis was applied to analyze field behaviors of test embankment of soft mucky deposit. Findings Finite element method results indicated that consolidation behaviors of PVD-improved soil with a nonlinear distribution of discharge capacity with depth were in a good agreement with the observed field behaviors, compared with those with a constant discharge capacity and a linear distribution of discharge capacity. At a given time and depth, the consolidation rate in the case of discharge capacity with a nonlinear distribution is lower than that of a linear or constant distribution. Practical implications A geotechnical engineer could use the proposed method to predict consolidation behaviors of drainage-installed ground. Originality/value Consolidation behaviors of PVD-installed ground could be reasonably predicted by using the proposed method with considering effect of discharge capacity reduction.

In this paper, effects of antecedent rainfall on stability of the unsaturated weathered granite slope at Inje, Korea were investigated. Effect of antecedent rainfall was considered in the numerical analysis using initial condition of matric suction, which was induced from field measurement. We also investigated case histories of slope failure, rainfall data, geotechnical properties, soil-water characteristic curve (SWCC) and hydraulic conductivity in those areas. Several sets of numerical stability analysis were performed on unsaturated slope with different initial matric suction. Result of the analyses indicated that the higher initial matric suction (less antecedent rainfall) of the unsaturated weathered granite slope delayed the slope failure. Also, unsaturated slope with higher saturated permeability is more vulnerable to rainfallinduced landslide than that with lower saturated permeability due to rainfall infiltration. Numerical analysis also indicated that a slope with wetting SWCC reached the failure condition earlier than a slope with drying SWCC.