多级时效荷载下双裂隙砂岩变形与破裂特征试验研究  

Experimental research on deformation and crack coalescence properties of sandstone containing two pre-existing fissures under multistage time-dependent loading

作　　者：杨超[1] 冯振华 王鑫 黄达[2] 

机构地区：[1]三峡大学三峡库区地质灾害教育部重点实验室,湖北宜昌443002 [2]重庆大学山地城镇建设与新技术教育部重点实验室,重庆400045

出　　处：《岩石力学与工程学报》2017年第9期2092-2101,共10页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(41602301;41502291;41172243)~~

摘　　要：实际工程中,岩体在进入最终应力状态前会经历多级时效荷载的作用。为研究该荷载下裂隙岩体强度、裂纹扩展和变形特征等的变化规律,以通过对砂岩切割并充填水泥砂浆制备的裂隙试样为对象,开展多级时效荷载下的三轴压缩试验。试验结果表明:多级时效荷载下,3种不同裂隙组合试样的强度较常规压缩均有一定程度的降低,陡缓和陡陡裂隙岩体的强度均在起裂强度σci和扩容应力σcd之间。裂纹扩展特征方面,在相同应力路径下,随着围压的增大,裂隙岩体的破坏呈现更强的剪切性质;缓缓裂隙组合岩体的破坏形式主要受裂隙本身的分布形态所控制,受应力水平和加载路径的影响较小,在试验中均以裂隙岩桥直接贯通发生破坏;相同围压条件下,陡缓和陡陡裂隙组合岩体在时效荷载作用下的破坏较常规压缩下的破坏表现出更强的张拉性质。利用Burgers蠕变损伤模型分析各岩体间的关系,指出岩体间变形的差异主要由裂隙特征导致的初始损伤差别和岩体处于不同强度区间而导致的不同时效损伤引起,为建立岩体时效损伤模型的进一步研究提供了参考。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 ？ciand 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.

关 键 词：岩石力学 双裂隙砂岩 多级时效荷载作用 裂纹扩展 时效损伤模型 

分 类 号：TU45[建筑科学—岩土工程]