| The water-rock interaction has become one of important direction with rock mechanics field. The existence and change of water-rock interaction are one of reasons for the instability of geotechnical engineering. Further more, the link between the mineral particles is weakened and the microstructure of rock mass is changed because of chemical corrosion effect. At the same time, the deformation of rock increases and the strength decreases. The result of water-rock interaction is that the mechanical properties of rock are changed due to the change of micro-components and the destruction of micro-structure in rock. Deformation, failure and its stability of engineering rock mass under the equivalent system of these factors are the commen problems confronted by many engineering subjects. The mechanism of water-rock interaction is very complex. The investigations on this project have pervasive theoretical meaning and practical value.This project is come from National Science Foundation Project (grant number: 50774093):Coupling theory of rheology-damage-fracture in fractured rock masses and application under water-rock interaction and Graduate Innovation Project of CSU (grant number:2009ssxt299- Study on subcritical crack growth and control of structure reduction). The research work involving several aspects as follows:(1) The conventional mechanical properties of water-rock interaction were tested. The expansion deformation of rock was increased in time, and approached a stable value by the end. The weakening of rock strength is obviously,η(?)<0.75. After water-rock interaction, the failure load, shear stress, normal stress and cohesive force all decreased, meanwhile, the variation of internal friction angle is not so obvious.(2) Five kinds of rock under water-rock interaction were tested using three-dimensional topography measurement instrument of Talysurf CLI 2000 type with high precision to achieve 0.5μm The test results conclude that the deviation degree of datum plane, the discreteness of rock's surface height and the roughness are increased after water-rock interaction. The distribution probability of highness is more concentrated. The process of Hydration, Hydrolysis and Dissolution is simultaneous. Lithology has played a leading role:Lherzolite> Migmatie> Peridotite> Amphibolite> Dolomite marble.(3) By using Instronl 1342 type electro hydraulic servo test machine, the constant displacement load relaxation method of double torsion(DT) specimens made of five kinds of rock were applied to study subcritical crack growth. The DT specimens were divided into two groups which one group was immersed in groundwater and the other in air. The results conclude that 1gK1-1gV curves of specimens after chemical corrosion locate top left corner of those of air specimens. The slope of curve is smaller and the intercept is bigger. It suggests that the subcritical crack growth speeds up because of water-rock chemical corrosion. Meanwhile, the fracture toughness KIC also decreased obviously due to water-rock interaction, for instance, the KIC of amphibolite decreased 39.46% and for marble,27.19%.(4) The stability of tunnel surrounding rock in the excavation process was calculated by using MIDAS/GTS software. The analysis capability of fluid-solid coupling can calculate the effects with or without seepage. In considering the seepage effect, the pore water pressure around tunnel decreased with the drop of water pressure in the cutting surface. The graph of decreased value range presented ribbon. After excavation the vertical stress fell about 30%, the level of X direction displacement changed little while the level of Z displacement changed greatly. So the surrounding rock will have the effect ofradial convergence. |
PDF Full Text Request