The John Mitchell Lecture 2022: Thinking conceptually about groundwater problems

Overview

Many excavations and tunnels experience problems and instability caused by uncontrolled groundwater inflows or pressures. Groundwater control measures are used to overcome these problems and create stable and workably dry conditions below groundwater level.

A key challenge for designers is that the performance of the various techniques is strongly influenced by the hydrogeological conditions at a site. Furthermore, the available ground investigation data may have gaps or be subject to considerable uncertainty regarding key parameters such as permeability or hydraulic boundary conditions. This means that there are some groundwater problems where analysis involves so many assumptions and uncertainties that the design outcomes are of little practical value.

This lecture will discuss how thinking conceptually about groundwater problems can be of great benefit when developing of groundwater control schemes, and that a robust conceptual model helps reduce the risk of designs being developed using inappropriate techniques. Examples will be given of cases where conceptual understanding of groundwater conditions proved vital in developing practical engineering solutions.