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深部岩体工程处于高应力环境中,开挖破裂后的工程岩体在持续的高地应力作用下具有很强的时间效应,深入研究其峰后蠕变特性,具有重要的理论和实际应用价值。先采用RMT-150B型岩石力学试验系统对完整岩样进行单轴峰前屈服、峰后破裂卸载试验,制备出具有不同破裂损伤程度的峰前屈服、峰后破裂的损伤岩样;再采用RLW-2000型微机伺服岩石三轴流变仪对其进行单轴蠕变试验,研究其单轴蠕变力学特性。研究结果表明:损伤岩样波速与完整岩样相比,均出现了不同程度的降低;损伤岩样各级应力水平下,瞬时应变量均是随着应力水平的增加而逐步增加,且均符合线性函数关系;相同应力水平下,峰后破裂损伤岩样瞬时应变明显大于峰前屈服损伤岩样;各级应力水平下,总体上各蠕变量随着应力水平的增加而逐步提高,且均符合指数函数关系;相同应力水平下,峰后破裂损伤岩样蠕变量明显大于峰前屈服损伤岩样,且随着荷载水平的进一步提高,两者差异程度增加;损伤岩样各瞬时变形模量随着应力水平的增加均逐步提高,两者之间符合线性函数关系;各应力水平下对应的瞬时变形模量存在明显差异,岩样损伤程度越高,瞬时变形模量越低;各损伤岩样在各级应力水平下,改进的西原模型能够较好地模拟其单轴蠕变特征。
Deep rock engineering is under high stress environment. The engineering rock mass after excavation and rupture has strong time effect under the action of continuous high ground stress. It is of great theoretical and practical value to deeply study its post-peak creep characteristics. First, the intact rock samples were subjected to uniaxial peak yielding and post-peak-breakage unloading tests by using the RMT-150B rock mechanics test system to prepare the damaged rock samples with different degrees of rupture before peak yielding and post-peak rupture. The RLW -2000 microcomputer servo rock triaxial rheometer for its uniaxial creep test to study its uniaxial creep mechanical properties. The results show that compared with intact samples, the velocity of damaged rock samples decreases in different degrees. The instantaneous strain increases gradually with the increase of stress level at all stress levels of damaged rock samples, Under the same stress level, the instantaneous strain of the post-peak cracked rock specimen is obviously larger than that of the pre-peak yielding rock specimen. At all levels of stress level, the creep amount gradually increases with the increase of stress level Which accorded with the exponential function. Under the same stress level, the creep amount of rock samples after the post-peak fracture was obviously larger than that of the rock samples before yield peak, and the difference between them increased with the further increase of load level. With the increase of stress level are gradually increased, the two line with the linear function between the corresponding stress levels corresponding to the instantaneous modulus of deformation there is a significant difference, the higher the degree of rock sample damage, the lower the instantaneous modulus of deformation; the damage Under the stress level of rock samples, the improved Nishihara model can simulate its uniaxial creep characteristics well.