Abstract
Many researchers have investigated the effect of basement excavation on tunnel deformation. However, the influence of consolidation on the interaction of basement-tunnel-soil is rarely considered or systematically studied in clay. In this study, three-dimensional coupled-consolidation finite element analyses were conducted to investigate the effect of consolidation on the tunnel response to excavation. An advanced nonlinear constitutive model was adopted, and numerical parametric investigations were conducted to study the effect of the excavation depth, tunnel stiffness, soil permeability coefficient, and consolidation time on the tunnel response. The results revealed that the basement excavation led to stress release, which caused tunnel heave. Owing to the dissipation of excess negative pore water pressure, the tunnel heave further increased to become approximately twice as large compared with that observed when the foundation pit excavation had just been completed. As the consolidation time increased, the longitudinal tunnel heave and tunnel diameter change caused by the foundation pit excavation gradually increased, but the growth rate was slower down. When the consolidation time changed from 50 days to 150 days, the maximum tunnel heave at the crown and the maximum tunnel diameter change increased by 1.18 and 1.48 times, respectively. The soil’s permeability coefficient did not have a significant effect on the tunnel heave at the crown nor on the tunnel diameter change. The results obtained by this study are expected to be useful as an engineering reference for the analysis of soil structure problems in clay.
Highlights
With the further progress of urbanization, the foundation pit engineering appears constantly, most of which are located in structures and densely populated areas
Based on the centrifugal model test, this paper investigated the effect of basement excavation on long-term tunnel deformation using the clay hypoplasticity model, which considers the small-strain, stress-path dependence, and soil consolidation characteristics
The main conclusions drawn from this study are summarized as follows: (a) The unloading of the basement excavation resulted in stress release, which caused tunnel heave
Summary
With the further progress of urbanization, the foundation pit engineering appears constantly, most of which are located in structures and densely populated areas. In current foundation pit engineering design, the effect of adjacent structures on the foundation pit and the effect of foundation pit excavation on adjacent structures should be considered The former is mainly to ensure that reasonable measures are taken to ensure the safety of foundation pit excavation and foundation construction, while the latter is to consider the excessive deformation of adjacent buildings caused by the excessive deformation of foundation pit, affecting the safety of structures. As a major engineering problem in urban underground space construction, it is essential to predict and evaluate the interaction between foundation pit excavation and adjacent structures. The deformation of adjacent tunnels as a result of basement excavation is such a typical problem in this kind of major engineering problems. To investigate the effect of tunnels due to a nearby basement excavation, numerous studies have been conducted using field tests [1,2,3,4,5], centrifuge model tests [6,7,8,9,10], and analytical and numerical methods [11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27]
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