STUDY ON MICROSTRUCTURE UNIT CHARACTER AND ITS SWELL-SHRINK PROPERTY FOR PHYSICO-CHEMICAL SOFT ROCK
物化型软岩微结构单元特征及其胀缩性研究

The physicochemical soft rock is a rock containing a great amount of clay minerals. Under engineering disturbance conditions, it is easy to swell and shrink by wetting and drying and to reduce rapidly its engineering properties. It is one of the biggest rock mechanics problems in geotechnical engineering. Because the physicochemical soft rock is of such physical and mechanical properties as hydrate swelling, strength dropping down and softening break etc.; it has brought a great influence on the stability of many important projects. Based on the analysis of the composition of the physicochemical soft rock, the microstructure shape change and swell-shrink mechanism in the drying-wetting process of the clay minerals, the swell-shrink geometrical model and its corresponding equation of the tetrahedral microstructure unit consisting of hard sand and clay minerals tactic strata in the physicochemical soft rock are put forward. This equation offers a theoretical foundation for the quantitative research of the swell-shrink property of soft rock. But it is necessary to do further study in the composition, mineral microstructure and mineral swell-shrink parameters etc. for its application in practice.