PARAMETRIC AND MECHANISM-BASED EVALUATION OF ANCHORED DIAPHRAGM WALL DISPLACEMENT IN SOFT CLAY

Abstract

Anchored diaphragm walls are widely used to control ground deformation and maintain stability in deep excavations in soft ground. Motivated by these challenges, this study investigates the lateral displacement of an anchored diaphragm wall system in soft clay in Thu Duc City, Ho Chi Minh City. The system consists of 800-mm-thick barrette diaphragm walls and prestressed ground anchors installed within a 13-m-thick soft clay layer, where the undrained shear strength ranges from 15 to 25 kPa. A two-dimensional finite element model using 15-node triangular elements in PLAXIS 2D is employed to simulate staged excavation and soil–structure interaction. A parametric study is conducted by varying prestressing force (0–100% of design load), anchor spacing (1.5–3.0 m), inclination angle (25°–45°), and the number of anchor levels. To support interpretation, an integrated FEM–XGBoost framework is adopted to quantify parameter importance and provide a mechanism-consistent ranking using a surrogate model. The results indicate that prestressing force is the dominant factor controlling wall displacement, reflecting the mobilization of tensile resistance. Displacement decreases significantly with increasing prestress, but improvement becomes marginal beyond approximately 80% of the design load. Inclination angle also has a strong influence through the horizontal component of anchor force, whereas spacing and number of anchor levels have limited effects within the investigated ranges. These findings provide a rational basis for optimizing anchor design in soft clay. The results are derived from two-dimensional numerical analysis and should be interpreted as indicative trends rather than exact field predictions.