Research And Application Of Constitutive Model Of Hydrous Rock Considering Water-Rock Interaction

In the construction of underground engineering, the existence of pore water in hydrous rock not only affects the physical and mechanical properties and instability, but also further influences the stability of rock engineering. Therefore, how to evaluate the stability of hydrous rock under the interaction of water rock has become the focus of research in rock mechanics and engineering. In this paper, the deteriorate effect of water rock interaction and failure mechanism of effective stress control were studied systematically by means of theoretical analysis, laboratory test, and numerical secondary development. The damage constitutive model of hydrous rock is established and the failure mechanism of hydrous rock is discussed. The main work is as follows.First of all, tri-axial compression tests were carried out to study the degradation law of rock cohesion, compressive strength and elastic modulus. And the damage mechanism of water rock interaction is analyzed. Then, the formation mechanism and influencing factors of pore water pressure in hydrous rock are studied by numerical simulation,and the effects of different saturation and pore structure on pore water pressure is analyzed. According to the effective stress principle, based on the Gassmann equation, the stress state of the rock under the action of the body stress and deviatoric stress is analyzed, and effective stress coefficient is established and the effective relationship between stress coefficient and pore structure is obtained. This can reveal the water rock interaction in the effective stress mechanism.Then, by using the deformation parameters and the evolution law of the effective stress coefficient, and based on the Mohr-Coulomb criterion,the incremental form of governing equation of water rock interaction is derived. The yield function and strength criterion are used to modify the stress, and the constitutive model of the hydrous rock under the action of effective stress is developed by using the VC language. The developed model can comprehensively consider the influence of pore water on the strength and deformation parameters and the effect of strain on the effective stress coefficient, which can reflect the deformation and failure characteristics of the rock.Finally, the mechanical properties of rock under different compression conditions and different water content are studied by using the constitutive model of hydrous rock, and compared with laboratory tests, the strength damage mechanism of hydrous rock under effective stress is further explained. Combined with engineering practice, the stability of surrounding rock in water rich tunnel is studied, and through the analysis of the displacement field, stress field, evolution of plastic zone, shows that the damage constitutive model which considering the water-rock interaction, can reflect the water rich rock excavation disturbance influence. And it meet the engineering site, can provide the basis for the stability control of the tunnel.