Deformation Behavior of Diaphragm Wall of a Deep Excavation Case in Luzhou Area
Date Issued
2008
Date
2008
Author(s)
Wen, Ting-Rui
Abstract
This study selected a deep excavation case in Luzhou area to investigate the deformation behavior of diaphragm wall during the whole process of construction. By using the data measured from inclinometers buried in the wall and strain gages installed on the strut, the history of load~deformation of diaphragm during various stages of construction can be thoroughly investigated. During the period of ground improvement before the excavation, the wall experienced significant outward displacement by jet grouting. The maximum deformation occurred at the depth near the top of grouting area. After the grouting, the wall deformation would rebound gradually with time. During the process of braced excavation, the total deformations of wall at each stage of excavation can be separated into four parts, resulted from the periods of standing-by(P1), excavating soils(P2), installing struts(P3) and preloading of struts(P4), respectively. At P1 stage, there is likely an increasing trend of wall movements and the strut loads remain unchanged. At P2 stage, the maximum displacement usually occurs below the excavation surface and the strut load is increased accordingly. At P3 stage, the wall deflection will increase continuously with time. Due to the effect of preload in P4 stage, the wall will move inwardly and the loads at upper struts will decrease simultaneously. The results of back analysis demonstrate that the estimated earth pressures deduced from the strut loads are larger than the theoretically predicted values. The leakage of water from wall surface caused the wall deformation and strut load increased immediately. Then the action of water refilling slows down the wall deformation and provides lateral support simultaneously. However the actions of seal-off grouting will result the increase of wall deformation and strut load. By simplification analysis, the pressure on the wall due to grouting is estimated to be around 1/6 of the grouting pressure.
Subjects
deep excavation
wall deformation
strut load
earth pressure
Type
thesis
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