岩石热黏弹塑性模型研究

RESEARCH ON THERMO-VISCO-ELASTOPLASTIC MODEL OF ROCK

温度作用下岩石的本构行为研究对于深部资源开采、核废料地下处置、地热资源开发以及地下军事防护设施建设等岩石工程问题具有重要意义。以西原体模型为基础,引入热膨胀系数、黏性衰减系数和损伤变量,综合考虑温度对岩石弹性变形、黏性流动以及结构损伤的共同影响,建立岩石热黏弹塑性本构模型,推导考虑温度效应的岩石蠕变方程和卸载方程。研究结果表明,在应力低于屈服极限的情况下,模型初始变形较快,然后趋于稳定蠕变,卸载曲线存在瞬时弹性变形、弹性后效和由温度引起的黏性流动;在应力高于屈服极限的情况下,变形逐渐转化为不稳定蠕变,卸载曲线存在瞬时弹性变形、弹性后效和由温度和应力共同引起的黏性流动。该模型较全面反映了岩石在温度作用下的黏弹塑性和损伤性质,适用于温度和载荷作用下岩石流变与稳定性分析。

The study of the thermal constitutive behavior of rock under temperature has guiding significances in rock engineering such as supporting of deep and soft rock roadway, disposal of nuclear waste underground, exploitation of geothermal resources and construction of military underground defensive facility. The differential thermo-visco-elastoplastic constitutive equation of rock which considers the influence of temperature on elasticity, viscosity and damage has been established based on the Nishihara rheological model by using thermal expanding coefficient, viscosity attenuation coefficient and damage variable. Creep equation and unloading equation of rock considering temperature effect have also been deduced. The results show that when stress is lower than yield stress, the model is in a fast deformation at beginning, then in a stable creep; and the unloading curve contains instantaneous elasticity, elastic aftereffect and viscosity flow induced by temperature. When stress is higher than yield stress, the model is in an unstable creep; and the unloading curve contains instantaneous elasticity, elastic aftereffect and the viscosity flow induced by the temperature and stress. This model reflects the visco-elastoplastic properties of rock, and can be used for analysis of rheology and stability of rock engineering.