A thesis submitted in partial fufillment of the requirements for the degree of Master of Engineering, School of Civil Engineering

Thesis (M.Eng.) - Asian Institute of Technology, 1999

This study focuses on the braced deep excavation in metropolitan Bangkok metropolitan using finite element program. Elastic-perfectly plastic Mohr-Coulomb soil model was adopted to simulate the soil behaviors involved in analysis. Firstly, Bangkok Subsoil profile is simplified and the associated soil properties were determined. Secondly, reference case of deep excavation were designed and modeled. Factors affecting the behavior of braced deep excavation were studied, which include: (1) wall stiffness; (2) strut (steel and concrete floor slab floor) stiffness; (3) horizontal spacing of strut; (4) vertical spacing of strut; (5) unsupported cantilever depth; (6) strut preloading; (7) friction angle of clay layers; (8) stiffness of clay layers. A series of influence charts obtained from numerical calculation are plotted and employed to estimate the maximum wall movement, maximum ground settlements, maximum bending moment, maximum shear force in deep excavation in Bangkok. 25 cases of deep excavation in metropolitan Bangkok were collected, compiled and analyzed. Estimations of maximum lateral wall movement of 20 cases, maximum ground settlement of 7 cases, maximum bending moment of 11 cases and maximum shear force of 4 cases of deep excavation projects have been performed in this study. Comparisons are also made for the of influence chart estimation, FEM prediction and field observation. It is shown that the estimation by using established influence chart are acceptable in the preliminary prediction analysis of deep excavation.