Predictions of changes in pore-water pressure around tunnels in clay

Any underground construction causes changes to the stress state in the ground and this change generally causes the generation of excess pore-water pressures in saturated fine grained soils. Subsequent dissipation of these pressures can lead to settlements and potential damage and hence there is a need to understand and predict these changes in pore-water pressure. Simple plasticity and non-linear elastic solutions have been used to calculate pore-water pressure changes as a tunnel is constructed in clay. These are compared with previous centrifuge tests involving the simulation of tunnel excavation as well as new tests specifically designed to investigate the generation and subsequent dissipation behaviour of excess pore-water pressures. The paper reports on the new tests, presents the findings within the simple plasticity and non-linear elastic analysis framework