Study On Constitutive Model For Hard Rock Under High Geostress Condition And Its Applications In Engineering

Numerical simulation has been an important research method for the design, optimization and stability analysis of large underground caverns under high geostress condition, but the precision of numerical simulation is not believable if we can not define the model and parameter exactly.Aiming at unique of mechanics behavior of hard rock under high geostress condition, using the large caverns of Laxiwa Hydropower Station as the applied engineering background, adopting new idea, basing on experimental study combined with theoretically analysis, numerical method, intelligent rock mechanics, a new method of studying constitutive model of hard rock under high geostress condition is proposed.The complicated evolvement of stress load,which is produced by excavating underground engineering under high geostress condition,is simulated through true triaxial experiment, and the strength and deformation character of hard rock under high geostress condition is obtained. A new Three Shear strength criterion and new Elastic-Brittle-Plastic constitutive model, which can describe the strength and deformation character of hard rock under high geostress condition, are established using theoretically analysis combined with numerical method and intelligent rock mechanics, basing on experimental study. The parameter of Elastic-Brittle-Plastic constitutive model is also obtained. Finally, applying the research fruits mentioned above to the numerical simulation of excavation and support schemes of the large caverns of Laxiwa Hydropower Station, the results show the rationality of Elastic-Brittle-Plastic constitutive model and it can be used in the design, optimization and stability analysis of large hard rock underground caverns under high geostress condition. Several aspects have been studied including:1. In response to the complicated evolvement of stress load,which is arised by excavating underground engineering under high geostress condition,true triaxial experiment is fulfilled to simulate the evolvement of stress load. Combining with uniaxial compression experiment, conventional triaxial compression experiment and acoustic emission inspection, the strength and deformation character of hard rock under high geostress condition are systemic researched.2. Aiming at the problem, that is, traditional strength criterion, including Mohr- Coulomb strength criterion, Griffith strength criterion, Drucker-Prager strength criterion, Two Shear strength criterion and Hoek-Brown strength criterion, has not been successful in predicting the strength of hard rock under high geostress condition, A new Three Shear strength criterion, which can reflect the strength character of hard rock under high geostress condition, is proposed based on analysis the establishing method of traditional strength criterion, the strength character of hard rock under high geostress condition obtained by experiment and intelligent rock mechanics method.3. Aiming at the problem that traditional elastic-plastic constitutive model has not been successful in predicting the failure depth and extent of hard rock under high geostress condition, a new Elastic-Brittle-Plastic constitutive model, which can reflect the mechanics character of hard rock under high geostress condition, is proposed based on traditional elastic-plastic constitutive model, the deformation character of hard rock under high geostress condition obtained by experiment and intelligent rock mechanics method.4. Applying the research fruits mentioned above to the numerical simulation of excavation and support schemes of the large caverns of Laxiwa Hydropower Station, the results show the rationality of Elastic-Brittle-Plastic constitutive model and it can be used in the design, optimization and stability analysis of large hardd rock underground caverns under high geostress condition.5. A new research method, which combining with experimental study, theoretically analysis, numerical method and intelligent rock mechanics method, is proposed, which can be used for reference when studying mechanics character of complicated geomaterial.