New Experiment System for the Interaction Between Soft Rock and Water : A Case Study on the Mogao Grottoes Support Rock

Abstract

The strength of rock strongly depends on the water content especially when the rocks contain clay materials. The interaction between soft rock and water always threaten the soft rock engineering projects. For this problem, new sets of laboratory experiment systems are developed to simulate the interaction between soft rock and water or vapor. In this paper, the principles of experiment systems are introduced with particular reference to the application on soft rock in Mogao Grottoes, one of the world famous ancient sites in China. Two kinds of rock samples, the sandstone and muddy sandstone, are obtained by insitu sampling system. Then the laboratory experiments are performed under different environment conditions. By the specific boundary conditions design, the physical-chemical effect and mechanic effect on water absorption of rock samples are separated for further mechanism study by the experiment system, and the different hydrological actions of water and vapor under variable experiment environment are obtained. The interaction mechanism is discussed with assistant methods, such as SEM (Scanning Electron Microscope), mercury injection test, X-ray diffraction analysis and etc. With the relation between water content and soft rock strength, the study may provide guidance and basis for the soft rock engineering in the future.