Abstract
Deep excavations are prone to result in excessive ground surface settlement displacement of surrounding existing structures, which could cause severe economic damage, even casualties. Hence, the optimization of pile parameters and evaluation of the stability of the excavation are of paramount importance. This paper aims to evaluate the security of deep excavation and optimize the parameters of supported piles in granular soils. An excavation case in granular soils is used to evaluate the stability of deep excavation using displacement least squares method. The stability of case history, Changqingqiao subway station, using pile and inner support system is evaluated by using the least square method. Subsequently, the finite element method is used to optimize the critical parameters of the supported piles, and it needs to be emphasized that the correctness and reasonability of the finite element (FE) models are evaluated according to field measurements. The optimum pile diameter and embedment ratio for single‐ and double‐row retaining pile are 1.0 m and 0.4. The maximum vertical displacement of surrounding soil and horizontal displacement of piles can be calculated by the equations obtained in this research which can provide useful guidance for the designing of deep excavation.
Highlights
With the proliferation of high-rise building and subway construction, deep excavations are commonplace in day-today geotechnical engineering projects
Deep excavations are prone to resulting in problems such as excessive ground surface settlement [1, 2], excessive displacement of surrounding facilities which could result in high economic damage and even loss of lives. erefore, the correct estimation of the ground displacements and evaluation of the stability of the excavation are of paramount importance
A quartic polynomial expression is introduced to fitting the settlement rule, as shown in equation (8). e RCL and LCL criteria are further applied to evaluate the ground settlement, and the results prove that the excavation is in a safe condition: y −1.59e− 7x4 + 6.03e− 5x3 − 0.0075x2 + 0.26x + 2.04
Summary
With the proliferation of high-rise building and subway construction, deep excavations are commonplace in day-today geotechnical engineering projects. Wei and Tan [12] investigated the performance of the deep excavation and the associated effect on the adjacent utility pipelines, and deflections of pile walls, ground surface settlements, and deflection of the existing structures. Han et al [15] investigated the design process and mechanical performances of deep excavation retained by tieback anchored pile walls using the finite element method and the elastic theory. The evaluation method for the stability of deep excavation induced by construction is scarce in the abovementioned literature, especially for deep excavation in granular soils. In this investigation, displacement least squares method is proposed to conduct a real-time evaluation of the stability of the excavation.
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