Diaphragm wall lateral movement in deep excavations in Bangkok clays: impacts and influencing factors

Abstract

Deep excavation in Bangkok clay layers involving diaphragm walls can cause ground movement, potentially affecting nearby structures. Understanding the magnitude and profile of this movement is crucial for assessing its impact on adjacent buildings. This study examines factors influencing the lateral displacement of rigid diaphragm walls in Bangkok’s deep excavations, including construction methods, excavation duration, depth ratios, soft clay depth, and system stiffness. The research data were collected from 230 dataset of lateral movement in diaphragm walls with a thickness ranging from 0.60 to 1.50 m. These walls had toe depths between 14 and 65 m, across various excavation depths ( H e ) from 6 to 35 m. Maximum lateral wall displacements ranged from 0.10% H e to 0.27% H e for the top-down method, and from 0.20% H e to 0.50% H e for the bottom-up method. If the system stiffness is sufficient, variations in wall thickness and construction method have minimal impact on wall deflection. However, with the bottom-up method and 1.0 m thick walls, long excavation times can lead to displacements up to 0.60% H e . This is mainly due to consolidation and creep in the clay beneath the area where the base slab construction is delayed.