Soil conditioning for EPB shield tunnelling

The use of conditioning agents that change the mechanical and hydraulic behavior of a cohesionless soil into an impervious and plastic paste is the key point for the correct management of EPB (Earth Pressure Balance) shield tunneling. The design of soil conditioning sets and the choice of the best products to be used require special laboratory tests. These tests should be carried out already at the design stage to allow to check if the needed results can be achieved in the soil to be excavated. In the paper an overview of the different type of laboratory tests that can be used on cohesionless soils are presented and the most important results that can be obtained are discussed.