明确荷载作用下的岩石损伤演化特性是分析岩石破坏机理的关键。通过引入与应变相关的宏观模量数学模型,建立了砂岩应变相关变形本构模型;基于损伤力学理论,结合所建立的本构模型,进一步分析了砂岩损伤演化规律;最后,使用岩石三轴加载系统,开展了不同加载速率和围压条件下的岩石单轴和三轴压缩试验,系统地验证了砂岩损伤演化模型的合理性。基于所建立的损伤模型,得到了砂岩初始损伤ω0,破坏损伤ωf和总损伤ωt。结果表明:在加载速率处于0.0~0.5 mm/min范围内变化时,加载速率对3种损伤的演化影响较小;围压在0~10 MPa范围内变化时,随着围压的增大,砂岩的初始损伤和总损伤不断减小,破坏损伤则几乎保持不变;破坏损伤作为岩石损伤阈值,受加载速率及围压影响较小且在一定范围内波动,这表明岩石内部裂纹扩展是使其破坏的诱因。最后,结合所提出的本构模型和损伤理论,确定了一种估算岩石原位模量的方法,可为相关工程提供理论参考。
Abstract
Defining the damage evolution characteristics of rocks under load is the key to analyze the damage mechanism of rocks. In this paper, a strain-related deformation intrinsic model of sandstone was developed by introducing a strain-related macro-modulus mathematical model. On the basis of the damage mechanics theory, the sandstone damage evolution law was analyzed by using the established intrinsic structure model. Moreover, uniaxial/triaxial compression tests were performed on rocks under different loading rates and surrounding pressure conditions using a rock triaxial loading system to systematically verify the rationality of the sandstone damage evolution model. The initial damage ω0, loading damage ωf and total damage ωt of sandstone were obtained. Results demonstrate that loading rate has a small effect on the evolution of the three types of damage when loading rate is varied in the range of 0.0-0.5 mm/min. When surrounding pressure changes in the range of 0-10 MPa, the initial damage and total damage of the sandstone keep decreasing with the increase of surrounding pressure, while loading damage remains almost constant. The loading damage, as the rock damage threshold, is less influenced by loading rate and surrounding pressure and fluctuates within a certain range, which indicates that the crack expansion within the rock is the causative factor of damage. Finally, a method for estimating the in-situ modulus of rocks is proposed by combining the intrinsic model and damage theory presented in this paper, providing theoretical references for related projects.
关键词
初始损伤 /
应变相关 /
变形本构模型 /
损伤演化 /
单轴和三轴压缩试验 /
岩石原位模型
Key words
initial damage /
strain dependence /
deformation constitutive model /
damage evolution /
uniaxial and triaxial compression test /
rock in-situ model
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基金
省部共建国家重点实验室开放课题(HJGZ2021206);高铁联合基金重点项目(U1934208);江西省科技合作专项项目(20212BDH81034)
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