Effects of Pile Installation on Existing Tunnels Using Model Test and Numerical Analysis with Medium Density Sand

Suk-Min Kong,Dong-Wook Oh,Seong-Won Lee,Chang-Yong Kim,Yong-Joo Lee

doi:10.3390/app11156904

Abstract

Vital underground structures such as sewers, power transmission lines, subways, and underpasses are potentially vulnerable to adverse effects from aboveground construction. In this study, the influence of pile installation on nearby existing tunnels was investigated. Both a laboratory model test and finite-element numerical analysis were conducted. Twelve different combinations of horizontal and vertical offsets between the pile and the tunnel were investigated. Different surcharge loads (allowable and ultimate) were also considered. In this way, the appropriate separation distance between the existing tunnel and the piles was established for sandy, medium-compaction soil. Although this study considers simple ground conditions, it facilitates safe construction by confirming the appropriate separation distance and comparing the areas that cannot be penetrated by the structures of each standard.

Highlights

Ground-space constraints in urban areas have led to the use of underground spaces for transportation, water supply, sewage, and power transmission
The mutual interaction of tunnels, piles, and soil following the installation of a pile in the soil above an existing tunnel by applying allowable and ultimate loads was analyzed through a laboratory model test and a finite-element numerical analysis
The conclusions of the study are as follows: 1. A laboratory model test was conducted to measure the effect on an existing tunnel of installing a pile nearby

Summary

Introduction

Ground-space constraints in urban areas have led to the use of underground spaces for transportation, water supply, sewage, and power transmission. Yao et al [2] used centrifuge tests to monitor the deformation of an existing tunnel lining due to pile loading; they found less deformation at larger pile–tunnel separation distances. They found that an increase in the length of the pile had a significant influence on the lining, regardless of tunnel size and excavation depth. Lueprasert et al [4] numerically analyzed the deformation of a tunnel with a vertical pile–tunnel offset of 3.0 Dt (where Dt is the outer diameter of the tunnel) at the top of the tunnel, varying the horizontal offset from 0.5 to 4.5 m under soft-clay and stiff-clay soil conditions They found that the positions of the pile tips and the stiffness of the ground layer are the main factors determining the deformation of the tunnel: when the horizontal Appl. A hole with a diameter of 100 mm was prepared at the center of the chamber for the

Model Test Equipment

Pretest for the Laboratory Model Test

Numerical Analysis

Findings

Discussion

Conclusions