Quantifying the role of wall–plug interface shear in the uplift stability of jet-grouted bottom plugs

Abstract

Jet-grouted bottom plugs are widely adopted in deep excavations to control groundwater inflow and resist hydraulic uplift. Conventional design approaches primarily rely on plug self-weight, often neglecting wall–plug interface shear interaction. This study presents a numerical investigation of interface shear behavior in the uplift performance of jet-grouted bottom plugs using PLAXIS 2D. The numerical model was verified against documented case histories for mechanical and hydraulic responses prior to a parametric study. Key parameters examined include plug thickness, overlying soil thickness, diaphragm wall embedment depth, plug permeability, cohesion, and interface reduction factor. Results indicate that accounting for wall–plug interface shear consistently increases uplift resistance, with the magnitude of the improvement varying with the investigated parameter range and the reference geometry. Within the investigated parametric ranges, plug thickness, overlying soil thickness, and wall embedment depth produced comparatively larger variations in the computed uplift response than plug material properties and the interface reduction factor. These observations represent comparative trends within the adopted numerical framework and should not be interpreted as a generalized sensitivity ranking. Permeability primarily influences seepage behavior, while the remaining parameters affect mechanical response to varying degrees within the adopted modeling framework. Based on these findings, a conceptual performance-informed design approach is outlined in which conventional preliminary design is refined through numerical modeling to account for soil–structure interaction and interface behavior. Results are derived from a two-dimensional plane strain framework and should be interpreted within the limitations of the adopted modeling assumptions.