Investigation of Three-Dimensional Deformation Behavior due to Long and Large Excavation in Soft Clays

Chunhui Lou,Nianwu Liu,Xiaonan Gong,Tangdai Xia

doi:10.1155/2019/4187417

Chunhui Lou, Nianwu Liu + Show 2 more

Open Access

https://doi.org/10.1155/2019/4187417

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Abstract

By analyzing the extensive field data from a long and large excavation in soft clay, this study investigates the three-dimensional deformation behavior induced by excavation. Significant inhibition effects of corner on both wall deflections and ground settlements were observed and quantified. Thus, a modified function for estimating the distribution of deformation parallel to the excavation is proposed and evaluated. Further analyzing shows that the pipeline settlement can be well estimated by the modified function combining with settlements profile proposed by Hsieh and Ou, and the reduction coefficient is about 0.8; the calculated maximum distortion of the pipeline can provide reliable reference. In addition, it is found that the cement-soil partition walls can also considerably reduce the wall deflections and ground settlements even after the part that is above the excavation base were removed.

Highlights

A lot of large-scale excavations are designed and constructed in an urban environment due to the demand for underground space
Lots of the early work had been done to analyze the performances of deep excavations [1,2,3,4,5] and the mechanical properties of soft clay [6, 7], a number of databases have been developed, and plane strain conditions are usually assumed in designing and estimation based on these studies
The limited quantity of the monitoring point may affect the accuracy of the calculated pipeline maximum distortion, the results suggest that using the ERFC curve to estimate the maximum distortion and the location of the occurrence has certain rationality

Summary

Introduction

A lot of large-scale excavations are designed and constructed in an urban environment due to the demand for underground space. It is important to ensure the stability and safety of excavations and the adjacent structures, especially in soft soil areas In this regard, lots of the early work had been done to analyze the performances of deep excavations [1,2,3,4,5] and the mechanical properties of soft clay [6, 7], a number of databases have been developed, and plane strain conditions are usually assumed in designing and estimation based on these studies. Numerical parametric analyze [14, 15] and centrifuge modeling [16] were adopted by some researchers to simulate the three-dimensional deformation performance of the excavation and its impact on adjacent tunnels. Some researchers have demonstrated that buried pipelines are vulnerable to damage by adjacent deep excavations [22,23,24]. us the settlement of a pipeline adjacent to this excavation was monitored and analyzed

Site Condition

Observed Deformation Behavior

Modified ERFC Fit Based on Survey Data from the Lotus Port Excavation

Prediction of Pipeline Settlement along the East Wall

Conclusions