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基于向家坝砂岩的常规三轴压缩试验和三轴压缩流变试验成果,分别通过应变等时曲线簇、稳态蠕变速率与应力水平的关系、裂纹损伤应力、流变荷载与破坏时间关系确定砂岩的长期强度,并比较这4种方法的适用性。结果表明:砂岩体积应变等时曲线簇的拐点比轴向应变、侧向应变等时曲线的拐点更为明显,而且其对应力水平和时间的反应更敏感;轴向稳态蠕变速率和侧向稳态蠕变速率与应力的关系符合指数函数关系,采用给定稳态蠕变速率阈值确定岩石长期强度比利用稳态蠕变速率-应力曲线的拐点确定长期强度更为合理;岩石的裂纹体积应变等时曲线簇以及其稳态蠕变速率与应力的关系也可以作为确定岩石长期强度的一种方法;岩石的裂纹损伤应力反映长期强度所在应力水平,为蠕变试验荷载分级提供依据。
Based on the results of conventional triaxial compression tests and triaxial compression rheological tests of Xiangjiaba sandstone, the relationship between steady creep rate and stress level, the relationship between crack damage stress, rheological load and failure time Determine the long-term strength of sandstone and compare the applicability of these four methods. The results show that the inflexion point of the isochronous curve of volumetric strain of sandstone is more obvious than the inflexion of axial strain and lateral strain isochronous curve, and it is more sensitive to stress level and time response. The steady axial creep rate and lateral The relationship between steady-state creep rate and stress accords with the exponential function. It is more reasonable to determine the long-term rock strength by using the threshold value of steady-state creep rate than the inflection point of steady-state creep rate-stress curve to determine the long-term strength. The volume-strain isochronous curve cluster and its relationship with the steady-state creep rate and stress can also be used as a method to determine the long-term strength of rock. The crack damage stress of rock reflects the stress level of long-term strength and provides the basis for creep test load classification.