Analytical Approach of the Arching Dual Effect Describing the Stability of Slurry-Wall Trenches in Cohesionless Soil

Abstract

Stability of slurry trenches is an important issue during the construction of groundwater cutoff and diaphragm walls and, thus, has gradually drawn additional attention. With the aim of controlling the stability and collapse mechanism of slurry walls better, an analytical approach based on interactions between horizontal and vertical arching effects was conducted to estimate the stability factors for general and local stability of a slurry-supported trench panel in cohesionless soils. The results show that arching has certain characteristics that affect soil behavior near the trench, including directions of loading and unloading of soil, variation of active pressure coefficient on the sidewall interface, and a created downward load transfer mechanism. The trench stability depends on two types of safety factors; the first factor prevents sliding collapse (overall stability), and the second factor prevents collapse of the soil interface (local stability) because local interface instability triggers overall trench collapse in cohesionless soil. The solution was compared with field measurements and three-dimensional (3D) finite-element analyses (with the effect of the third dimension), which permitted study of the influence of the arch located in the third direction. The satisfactory correspondence validates this approach and shows that the 3D analytical analysis perfectly describes the phenomenon.