Slurry tunnelling uses a water based slurry to aid in tunnel face support and transportation of the excavated material. Unlike other tunnelling methods this requires expensive surface separation plant to remove the excavated ground from the slurry. Incorrect specification of this plant can lead to significant delays and added cost to a tunnel drive. Due to the tight budgets and space constraints this can cause contracts to become unprofitable, in particular where small diameter slurry tunnels are excavated by pipe jacking. For this reason accurate prediction of the size distribution of the soil particles and lumps in the disaggregating slurry is required. This research concerns the development of test procedures and methods of soil classification that will enable improved predictions of the degree to which soils/weak rocks will disaggregate during the slurry tunnelling process
