A New Equation for Estimating the Required Face Support Pressure in EPB Machine
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ORIGINAL PAPER
A New Equation for Estimating the Required Face Support Pressure in EPB Machine Sadegh Haji . Hamid Chakeri
Received: 26 October 2019 / Accepted: 25 September 2020 Springer Nature Switzerland AG 2020
Abstract Tunnel face instability and the potential surface settlement are the most hazardous factors that should be considered in all tunneling methods applied in urban areas. There are several published relationships concerned with field measurements and analytical solutions to estimate the amount of the required face support pressure value due to tunneling. The first purpose of this study is to determine the effective parameters such as geotechnical factors (cohesion, internal friction angle, density, Young’s modulus, and Poisson’s ratio), and engineering factors (tunnel depth and tunnel diameter) on the required face support pressure value. In this study, three metro project constructions, namely Tabriz, Istanbul, and Mashhad, were chosen in the Middle East. The main aim of this study is to present better equations for estimating the required face support pressure based on actual data sets from several tunnel projects and numerical modeling. The results from the new estimation equation are compared with the results of empirical and field observations. The required face support pressure values obtained from the new equation have good agreement with the actual results for three different metro case studies.
S. Haji H. Chakeri (&) Department of Mining Engineering, Sahand University of Technology, Tabriz, Iran e-mail: [email protected]
Keywords Numerical modeling Shield tunneling Face support pressure Empirical-analytical method
1 Introduction Considering population growth and urbanization, it is effective to build underground metro tunnels to reduce traffic congestion in urban areas. These tunnels tend to be at shallow depths and near urban infrastructures. So the ground movements and surface settlements induced by these tunnels are essential for the safety of surface structures. Therefore, engineers have always have sought to use better excavation methods such as mechanized methods to stabilize the tunnel face and minimize movements and surface settlements. Earth pressure balance (EPB) tunneling is a mechanized excavation method widely used for tunneling in urban areas because of its excellent characteristics such as fast and safe excavation, tunnel face stability and lower surface settlement effect, etc. The EPB method has some advantages over other methods, such as better control of face stability and lower surface settlement. However, in some metro projects, face instability and surface settlement problems can be seen. There are many effective parameters, including soil properties, tunnel depth, and tunnel diameter, to estimate the required face support pressure and surface settlement values.
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Geotech Geol Eng
Although, some researchers have proposed various relationships to estimate the required amounts of face support pressure
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