Research On Prediction Of Ground Movement Due To Excavation In Soft-soil Area

In the process of excavation in soft-soil area, the excavation will not only lead to the bottom heave and the displacement of retaining wall, but also lead to the horizontal and vertical displacement around the excavation which will have an important impact on the surrounding environment. Especially for the excavation in the heart of the city, the surrounding buildings, municipal roads and pipelines require very strict deformation and a high level of environmental protection. Therefore, in order to ensure the smooth progress of construction and the safety of the surrounding environment, it is necessary to study the the soil displacement, in particular the ground surface settlement.On the basic of the summary on the characteristics, mechanism and influential factors of the excavation deformation, the characteristics of the empirical prediction methods of the soil displacement outside the excavation are analyzed. The excavation -induced displacement of the soil is studied using numerical analysis method in this paper. The main tasks include:(1) The numerical simulation of the excavation shows that, for each basic deformation modes of the retaining wall, for example the forward rotation, reverse rotation and deflection, the ground surface settlement shows more obvious laws of distribution, which can be fitted by the exponential curve with a unified format. At the same time, for the three basic deformation modes, the distribution of the horizontal and vertical displacement of the soil can be fitted by experience curves.(2) Arbitrary displacement pattern envelope of the retaining wall can be fitted using the three basic deformation modes above, and the maximum displacement value for each basic deformation mode can be obtained. Using the experience curve above, the corresponding component of the ground surface settlement for each basic deformation mode can be calculated. Then superimpose the three settlement component and obtain the distribution curve of ground surface settlement.(3) Similar to the above method, arbitrary displacement pattern envelope of the retaining wall can be fitted using the three basic deformation modes above, and the maximum displacement value for each basic deformation mode also can be obtained. Using the experience curve calculated by the numerical analysis method, the corresponding component of the horizontal and vertical displacement for each basic deformation mode can be calculated. Then superimpose the three component of the horizontal and vertical displacement and obtain the distribution curve of the horizontal and vertical displacement of deep soil.(4) Based on the analysis of measured data of the ground surface settlement, the timing - projection pursuit regression model is proposed, which can be considered both time series and the highly nonlinear fitting performance. With good practicality, the method provides a better way to predict the ground surface settlement dynamically, and is an important referee to the dynamic design and informative construction for the excavation engineering.