热力耦合作用下花岗岩流变模型的本构关系研究

STUDY OF CONSTITUTIVE EQUATION OF GRANITE RHEOLOGICAL MODEL WITH THERMO-MECHANICAL COUPLING EFFECTS

热力耦合作用下岩石的微观结构的变化是引起宏观力学变化的主要原因,从热力耦合作用下花岗岩的流变机制研究出发,建立热力耦合作用下花岗岩的流变模型,从而推导流变本构方程是一种可行的方法。通过热力耦合作用下花岗岩的流变机制研究可知:(1)花岗岩是一种由多种成分构成的具有多晶复合介质特点的脆性坚硬岩石,具有很大的非均质性,内部微观结构可分为晶粒、晶粒边界、晶间胶结物及晶间孔隙,这样的组分和结构将决定花岗岩在热力耦合作用下的流变特性。(2)热力耦合作用下花岗岩流变现象主要是热力耦合作用下岩体内晶间胶结物及晶粒内部产生的位错及微破裂过程,即温度产生的热破裂和应力产生损伤破裂的复合破裂过程,微观结构上的变化使得标志着热力耦合作用下宏观力学特性的力学参数成为温度的函数。因此,将岩石现象流变学与物理流变学结合起来,提出热力耦合作用下岩石热黏弹塑性流变元件力学元件,在广义西原模型的基础上建立热力耦合作用下花岗岩流变模型,推导出可描述150MPa及600℃以内花岗岩的流变本构方程,用试验结果验证了其适用性和合理性。热力耦合作用下花岗岩流变模型的本构方程的建立为高温岩体地热开发钻井施工及其稳定性研究提供了依据。

The change of rock microstructure with thermo-mechanical coupling effects is the main cause for transformation of macroscopic mechanics of rock. The rheological mechanism of granite with thermo-mechanical coupling effects; and rheological model of granite are researched. As a result, it is a kind of feasible way for building rheological constitutive equation. According to the research on rheological mechanism of granite with thermo-mechanical coupling effects, it knows： （1） Granite is a sort of brittleness and hardness rock constituted with multi-ingredient; it is provided with polycrystal multiple medium and prodigious anisotropic. Microstructure inside of granite can be divided into grain, boundary of grain, intercrystalline cement and intercrystalline pore; such ingredient and structure determine the rheological properties of granite with thermo-mechanical coupling effects. （2） The rheological phenomenon is induced by dislocation and cracking of grain and cement of grain with thermo-mechanical coupling effects, which is a compound rupture process with thermal cracking by temperature and damage cracking by stress. So macro-mechanical properties of mechanical parameters become a function of temperature. Therefore, the viscoelasto-plastic rheological elements of mechanical model combining the phenomenon of rock rheology and physical rheology are proposed; and the rheological model of granite with thermo-mechanical coupling effects on the basis of generalized Nishihara rheological model is constructed. The evolution model is deduced, which can describe 150 MPa and 600 ℃ granite within the evolution of the constitutive equation; and experimental results show its application and rationality. Granite model of the constitutive equation with thermo-mechanical coupling effects provides a basis for the establishment of high- temperature geothermal development drilling rock of stability.