Evaluation of Performance of Diaphragm Walls by Wall Deflection Paths for Deep Excavations in Central Ha Noi

Abstract

The objective of this paper is to evaluate the performance of diaphragm walls by wall deflection paths for deep excavations in Central Ha Noi. The commercial software PLAXIS 2D was used as a numerical tool for 2D finite element analyses in this paper. A deep excavation in Central Ha Noi is adopted as a basis for numerical analyses in this study. A benchmark analysis was firstly conducted on the excavation to verify the validity of material models and their input parameters for predicting wall deflections; following that the reference envelopes of wall deflection paths were delivered for various conditions of deep excavations in Central Ha Noi. Considering the current prediction, up to 72 mm of the maximum lateral wall displacement for an excavation have a 21.9 m of excavation depth. However, some assumptions made have to be further confirmed by comparing data observed later on. Reference envelopes of excavations have been developed and discussed in various conditions of the excavation. It is first found that the maximum lateral wall displacement at the first stage of excavation is roughly inversely proportional to the Young’s moduli of soils. In conclusion, changing wall thickness leads to the limited difference in reference envelope at shallow excavation stage, but it may not be true when the excavation goes deeper.