Three Dimensional Analysis of Earth Pressure Balance (EPB) Shield Tunneling in Soft Bedrock

Abstract

There are a numbers of factors influencing the bedrock deformation caused by shield tunneling. Although many domestic and foreign scholars from the field of geotechnical engineering have conducted theoretical researches on the deformation thereof at the present time, engineering formulas and empirical statistics cannot be solely applied to complex fractured bedrock with discontinuous deformation, as complex calculation and thoughtlessness can result in an error in model adaptability and calculation applications. Thanks to the development of Plaxis 3D, a finite element method (FEM) program, we are able to simulate complicated deformation issues in a non-linear model and to analyze the stress and strain thereof. By taking the “CM01 Construction Contract Project of Taoyuan International Airport Access MRT System extended to Zongli Train Station” as an example, this study simulates the ground surface settlement deformation induced by shield tunneling and compares the longitudinal and vertical deformation curves thereof with the results of on-site monitoring equipment. The HOEK-BROWN model is also adopted to provide more precise results than the traditional Mohr-Coulomb model. In the simulation of shield tunneling, it is a must to take the shield tail grouting, shield jack thrust force and cutter head pressure into consideration by having a rather stable longitudinal settlement curve. This helps to explore ideal simulations of bedrock tunneling, to which other projects with similar conditions can be referred. Keywords—Tunneling, Rock mass, Ground Settlement, FEM