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实际工程中,岩体的应力变化状态非常复杂,并不只是简单的加载或者卸荷,如水利工程中的大坝,当坝基开挖时其力学条件主要表现为开挖方向的卸荷(其他方向有可能卸荷,也有可能加载),而坝体修筑以后,力学条件又主要表现为加载。因此,对卸荷损伤后的岩体再次加载时的力学性质进行研究具有十分重要的工程意义。通过三轴卸荷及卸荷损伤后加载破坏试验,研究了不同围压下,含断续预制节理岩体经过不同程度卸荷损伤后再次加载时的力学特性。研究结果表明:围压对于含断续节理岩体变形模量影响不明显,岩体弹性模量与围压没有明显关系,相同围压下节理岩体弹性模量和变形模量均显著低于完整岩体:节理岩样峰值应变随着围压的增大线性增大,二者之间有较好的相关性,相比于完整岩样,节理岩体峰值应变随围压增大增长更快:围压越低,卸荷对岩体强度的影响越大,随着围压增加,卸荷量不同造成岩样的损伤差异逐渐减小。
In practical engineering, the state of stress change of rock mass is very complicated, not just a simple loading or unloading, such as a dam in water conservancy project. When the dam foundation is dredged, the mechanical conditions mainly show as the unloading in the excavation direction The direction of unloading may also be possible to load), and after the dam is built, the mechanical conditions are mainly manifested as loading. Therefore, it is very important engineering significance to study the mechanical properties of rock mass after unloading and reloading. Through three-axis unloading and post-damage unloading damage test, the mechanical properties of the rock mass under intermittent prefabricated jointed joints under different confining pressure after being reloaded with different degrees of unloading damage were studied. The results show that the confining pressure has no obvious effect on the deformation modulus of discontinuous jointed rock mass, and the elastic modulus of rock mass has no obvious relationship with confining pressure. The elastic modulus and deformation modulus of jointed rock mass under the same confining pressure are significantly lower than In intact rock mass, the peak strain of jointed rock mass increases linearly with the increase of confining pressure, and there is a good correlation between the two. Compared with intact rock mass, the peak strain of jointed rock mass increases with the increase of confining pressure Fast: the lower the confining pressure, the greater the impact of unloading on the rock mass strength. With the increase of confining pressure and the different unloading amount, the damage difference of rock samples gradually decreases.