Creep constitutive model considering nonlinear creep degradation of fractured rock

• Published in: International journal of mining science and technology Vol. 34; no. 1; pp. 105 - 116
• Main Authors: Chunping, Wang, Jianfeng, Liu, Liang, Chen, Jian, Liu, Lu, Wang, Yilin, Liao
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2024; Beijing Research Institute of Uranium Geology,Beijing 100029,China; School of Architecture and Civil Engineering,Xihua University,Chengdu 610039,China; CAEA Innovation Center for Geological Disposal of High-Level Radioactive Waste,Beijing 100029,China%State Key Laboratory of Hydraulics and Mountain River Engineering,Sichuan University,Chengdu 610065,China%State Key Laboratory of Hydraulics and Mountain River Engineering,Sichuan University,Chengdu 610065,China; Elsevier
• Subjects: Beishan granite; Creep; Damage; Fractured rock; Geological disposal; Beishan granite; Geological disposal; Creep; Damage; Fractured rock
• ISSN: 2095-2686
• DOI: 10.1016/j.ijmst.2023.11.008

Stability analysis of underground constructions requires a model study of rock masses’ long-term performance. Creep tests under different stress conditions was conducted on intact granite and granite samples fractured at 30° and 45° angles. The experimental results indicate that the steady creep strain rates of intact and fractured rock present an exponential increase trend with the increase of stress level. A nonlinear creep model is developed based on the experimental results, in which the initial damage caused by fracture together with the damage caused by constant load have been taken into consideration. The fitting analysis results indicated that the model proposed is more accurate at identifying the full creep regions in fractured granite, especially the accelerated stage of creep deformation. The least-square fit error of the proposed creep model is significantly lower than that of Nishihara model by almost an order of magnitude. An analysis of the effects of elastic modulus, viscosity coefficient, and damage factors on fractured rock strain rate and creep strain is conducted. If no consideration is given to the effects of the damage, the proposed nonlinear creep model can degenerate into to the classical Nishihara model.