Experimental research on deformation and crack coalescence properties of sandstone containing two pre-existing fissures under multistage time-dependent loading
YANG Chao1，FENG Zhenhua1，WANG Xin1，HUANG Da2
(1. Key Laboratory of Geological Hazards on Three Gorges Reservoir Area，Ministry of Education，China Three Gorges University，Yichang，Hubei 443002，China；2. Key Laboratory of New Technology for Construction of China in Mountainous Area，
Chongqing University，Chongqing 400045，China)
Abstract：Rocks in engineering projects experience usually the multistage time-dependent loading before reaching the final stress state. The triaxial compression experiments in laboratory were performed in order to investigate the effect of multistage time-dependent loading on the strength failure and crack coalescence behavior. The tests results showed that all the strengths of sandstone samples with three types of preexisting closed flaw pairs respectively under the multistage time-dependent loading decreased to some extent compared with those under conventional triaxial compression tests. For the type of specimens with high-low angle and high-high angle，the values of the strength under the multistage time-dependent loading were between the initiation stress level ?ci and the critical stress of dilation ?cd. Under the same stress loading path，the fractured rock showed the strong characteristics of shear failure with the increase of confining pressure. All of the low-low angle type of specimens showed the mode of rock bridge failure，indicating that the failure mode of the low-low angle type of specimens is mainly controlled by the distribution of the fracture itself，the influence of stress level and loading path is small. Under the multistage time-dependent loading，the failure of high-low angle and high-high angle type of specimens showed the mode of tensile failure. Burgers model for damage creep was used to analyze the relationship of these rock masses.
[1] 李永盛. 单轴压缩条件下四种岩石的蠕变和松弛试验研究[J]. 岩石力学与工程学报，1995，14(1)：39–47.(LI Yongsheng. Creep and relaxation of 4 kinds of rock under uniaxial compression[J]. Chinese Journal of Rook Mechanics and Engineering，1995，14(1)：39–47.(in Chinese))
[2] 杨 超. 硬质裂隙岩体三轴加载及卸荷蠕变特性研究[博士学位论文][D]. 重庆：重庆大学，2015.(YANG Chao. Study on the triaxial loading and unloading creep properties of fractured hard rock[Ph. D. Thesis][D]. Chongqing：Chongqing University，2015.(in Chinese))
[3] 陈德基，余永志，马能武，等. 三峡工程永久船闸高边坡稳定性研究中的几个主要问题[J]. 工程地质学报，2000，8(1)：7–15.(CHEN Deji，YU Yongzhi，MA Nengwu，et al. Some main problems on the stability of high permanent shiplock slope for three-gorges project[J]. Journal of Engineering Geology，2000，8(1)：7–15.(in Chinese))
[4] 黄润秋，黄 达，段绍辉，等. 锦屏I级水电站地下厂房施工期围岩变形开裂特征及地质力学机制研究[J]. 岩石力学与工程学报，2011，30(1)：23–35.(HUANG Runqiu，HUANG Da，DUAN Shaohui，et al. Geomechanics mechanism and characteristics of surrounding rock mass deformation failure in construction phase for underground powerhouse of Jinping I hydropower station[J]. Chinese Journal of Rook Mechanics and Engineering，2011，30(1)：23–35.(in Chinese))
[5] 邓广哲，朱维申. 蠕变裂隙扩展与岩石长时强度效应实验研究[J]. 实验力学，2002，17(2)：178–183.(DENG Guangzhe，ZHU Weishen. An Experiment research on the crack propagation in rockmass[J]. Journal of Experimental Mechanics，2002，17(2)：178–183.(in Chinese))
[6] 赵延林，万 文，王卫军，等. 类岩石裂纹压剪流变断裂与亚临界扩展实验及破坏机制[J]. 岩土工程学报，2012，34(6)：1 050–1 059. (ZHAO Yanlin，WAN Wen，WANG Weijun，et al. Compressive-shear rheological fracture of rock-like cracks and subcritical crack propagation test and fracture mechanism[J]. Chinese Journal of Geotechnical Engineering，2012，34(6)：1 050–1 059.(in Chinese))
[7] LI X，KONIETZKY H. Numerical simulation schemes for time-dependent crack growth in hard brittle rock[J]. Acta Geotechnica，2014，DOI：10.1007/s11440–014–0337–9.
[8] 黄 达，杨 超，黄润秋，等. 分级卸荷量对大理岩三轴卸荷蠕变特性影响规律试验研究[J]. 岩石力学与工程学报，2015，34(增1)：2 801–2 807.(HUANG Da，YANG Chao，HUANG Runqiu，et al. Experimental research of unloading triaxial rheological characteristics of marble affected by different step unloading values[J]. Chinese Journal of Rock Mechanics and Engineering，2015，34(Supp.1)： 2 801–2 807.(in Chinese))
[9] HUANG D，CEN D F，MA G W，et al. Step-path failure of rock slopes with intermittent joints[J]. Landslides，DOI：10.1007/ s10346–014–014–0517–6.
[10] 杨 超，黄 达，黄润秋，等. 断续双裂隙砂岩三轴卸荷蠕变特性试验及损伤蠕变模型[J]. 煤炭学报，2016，41(9)：2 203–2 211. (YANG Chao，HUANG Da，HUANG Runqiu，et al. Experimental research on the triaxial unloading creep characteristics of stone with two pre-existing cracks and its damage creep model[J]. Journal of China Coal Society，2016，41(9)：2 203–2 211.(in Chinese))
[11] HUANG D，GU D，YANG C，et al. Investigation on mechanical behaviors of sandstone with two preexisting flaws under triaxial compression[J]. Rock Mechanics and Rock Engineering，2016，49(2)：375–399.
[12] 闫子舰，夏才初，李宏哲，等. 分级卸荷条件下锦屏大理岩流变规律研究[J]. 岩石力学与工程学报，2008，27(10)：2 153–2 159.(YAN Zijian，XIA Caichu，LI Hongzhe，et al. Study on rheological rules of marble in Jinping Hydropower Station under conditions of step unloading[J]. Chinese Journal of Rock Mechanics and Engineering，2008，27(10)：2 153–2 159.(in Chinese))
[13] 朱维申，齐银萍，郭运华，等. 锦屏I级水电站地下厂房围岩变形破裂的三维损伤流变分析[J]. 岩石力学与工程学报，2012，31(5)：865–872.(ZHU Weishen，QI Yinping，GUO Yunhua，et al. 3D damage rheology analysis of deformation and fracture of surrounding rocks in Jinping I hydropower station underground powerhouse[J]. Chinese Journal of Rock Mechanics and Engineering，2012，31(5)：865–872.(in Chinese))
[14] 徐 鹏，杨圣奇. 循环加卸载下煤的黏弹性蠕变本构关系研究[J]. 岩石力学与工程学报，2015，34(3)：537–545.(XU Peng，YANG Shengqi. Study of voscp-elastic-plastic constitutive model of coal under cyclic loading[J]. Chinese Journal of Rock Mechanics and Engineering，2015，34(3)：537–545.(in Chinese))
[15] 赵延林，唐劲舟，付成成，等. 岩石黏弹塑性应变分离的流变试验与蠕变损伤模型[J]. 岩石力学与工程学报，2016，35(7)：1 297–1 308. (ZHAO Yanlin，TANG Jinzhou，FU Chengcheng，et al. Rheological test of separation between viscoelactic-plastic strains and creep damage model[J]. Chinese Journal of Rock Mechanics and Engineering， 2016，35(7)：1 297–1 308.(in Chinese))
2017, Vol. 36 
