【摘要】 为研究地下深部洞室围岩的蠕变力学特性,以甘肃北山深部地质处置地下实验室为研究背景工程,开展不同加卸载应力路径下的三轴蠕变试验,有效揭示洞室花岗岩的蠕变变形特征与破坏机制,提出一个确定花岗岩长期强度的方法。研究结果表明:1)不同加卸载应力路径下的花岗岩均具有蠕变阀值;2)蠕变速率受围压和偏应力水平的影响较大,且横向变形相较于轴向变形更为敏感,这一规律在卸荷蠕变时最为明显,导致卸荷蠕变扩容比加载蠕变更加突出;3)加载蠕变岩样的破坏模式主要为剪切破坏,卸荷蠕变的破坏模式主要为拉剪破坏;4)岩石长期强度可以通过岩石的变形模量-时间曲线来确定,得到的流变长期强度与流变破坏强度的比值即σ∞/σf为0.626～0.717,比传统方法减少4%左右。更多还原

【Abstract】 In order to study the rheological mechanical properties of the surrounding rock of the deep underground caverns, the triaxial rheological tests of hard brittle diabase in different stress paths were carried out by using granite specimens from deep geological disposal underground laboratory in Beishan, Gansu Province. The tests reveal the creep deformation characteristics and failure mechanism of granite. A method for determining the long-term strength of granite was proposed. The results show that: 1) threshold effect exists both in the unloading confining pressure rheological tests and the triaxial loading rheological tests; 2) creep rate is influenced by confining pressure and deviatoric stress level, and unloading rheolog dilatation is more prominent than loading rheolog; 3) the diabase specimens all show brittle failure in unloading and loading rheological tests, and the failure pattern in triaxial loading rheological tests is mainly in the form of shear failure while it is the tensile shear failure in unloading confining pressure rheological tests; 4) the long-term strength of rock can be determined by the deformation modulus-time curve of rock. σ∞/σf is 0.626-0.717, which is about 4% less than that of the traditional method.更多还原