This paper presents an improvement on a previous model for predicting the Marsh funnel (MF) test that is used in slurry shield tunneling for evaluating the rheological properties of bentonite slurries. The improvement focuses on the prediction of the dynamic part for fluids with small MF times. The velocity profile of the Herschel-Bulkley fluid in a laminar pipe flow condition is first investigated and a correction factor is introduced in the improved model. Comparisons of results from experiments and calculations with the previous model confirm the improved performance over the existing model. The rheological parameters obtained from the improved model show good resemblance to those obtained from a laboratory viscometer. The work also provides a reference to similar applications such as fluid transportation through pipelines where dynamic pressure dominates and therefore should be correctly predicted considering its velocity profile in a laminar condition.

Tunnel-boring machine (TBM) tunnelling through an aquifer will generate excess pore water pressures in the soil around the tunnel face. Accurately predicting the magnitude of the excess pore water pressures is significant because it directly determines the effective face support pressure. In this study, an analytical solution for transient cylindrical flow caused by TBM tunnelling considering the elastic storage of the aquifer is developed. Furthermore, a quasi-static solution to couple the effect of slurry infiltration with the elastic storage is presented. It is shown that the pore water pressures derived from the analytical solution match quite well with the measurements obtained in proximity to as well as far away from the TBM. The coupled quasi-static solution also agrees with the measurements for the places close to the tunnel face, but underestimates the observations far away from the tunnel face. The results also show that a larger infiltration distance leads to a slower dissipation of excess pore water pressures, which does not make a difference during excavation (when excavation velocity is faster than the pore fluid velocity).