A Comparison of Empirical and Numerical Approaches for Estimating Rock Support Pressure on Permanent Tunnel Lining

In Hong Kong, the rock support pressure acting on the permanent tunnel lining is usually estimated using the empirical equations by Terzaghi's rock arching theory (1946) and Grimstad & Barton’s Q support pressure (1993). However, with the advanced technologies, the assumptions behind these studies may become too conservative and subsequently lead to high construction cost and time. According to the Geoguide 4 (2018 Edition), it is suggested that the rock support pressure should be estimated either by an empirical method or an analytical/numerical assessment. By establishing different comparison models, this paper investigates the difference in estimated rock support pressure acting on the permanent lining using empirical approaches and finite element modelling. The influence of missing parameters in empirical equations and the rock mass behavior around the excavation profile are also studied.