Quantitative estimation of swelling and slaking characteristics for soft rockmass

Swelling and slaking of soft rocks have close relationships with the extrusion of tunnel wall, rapid weathering of cutting slope, landslide and so on. So it is important to grasp the characteristics. However, becsuse of the facts that much time has to be put in the experiment and it is difficult to lay hold of the properties quantitatively, experiments and surveys have not been made sufficiently. The authors have proposed some simple and rapid tests to solve this problem(Kojima et al 1977). We can divide the factors which govern swelling and slaking of soft rocks into two different types. One is the internal factors based on the rock itself, and the other the external ones such as moisture content in rocks. In the former factors, latent possibility of swelling and slaking determined by the grain size distribution of rock itself and species of clay minerals, and extent of compaction are important, especially in soft rocks, special considerations have to be given to so called extent of solidification based on texture and cementation of grains. In simple and rapid test, these factors can be expressed by the following variables.