含偏心裂隙类岩石劈裂强度及破坏特征试验  

Experimental study on tensile strength and splitting failure characteristics of rocks⁃like with eccentric cracks

作　　者：黄耀光 李杨杨 杨晚霞 HUANG Yaoguang;LI Yangyang;YANG Wanxia(College of Science,Xi'an University of Science and Technology,Xi'an,Shaanxi 710054,China)

机构地区：[1]西安科技大学理学院,陕西西安710054

出　　处：《采矿与安全工程学报》2024年第4期824-835,共12页Journal of Mining & Safety Engineering

基　　金：国家自然科学基金项目(51604214);陕西省自然科学基金项目(2019JQ-381);中国博士后科学基金项目(2016M592818)。

摘　　要：为探究偏心裂隙对岩石拉伸力学性能的影响机制,利用自主设计的加工装置制备了具有不同偏心距和倾角的预制裂隙类岩石试样,对其开展平台巴西劈裂试验和非接触全场应变监测试验,并基于载荷⁃位移曲线和表面应变场演化,分析了偏心距和倾角对变形、拉伸强度和劈裂破坏的影响,揭示了拉伸强度劣化规律及劈裂破坏原因。结果表明:试样表面应变在压密和近似线弹性变形阶段基本不变,在裂纹稳定扩展和非稳定扩展阶段发生从缓慢增加到急剧增加的变化;相同裂隙倾角下,偏心裂隙试样的拉伸强度随偏心距增大而增大,且偏心距对拉伸强度的劣化影响远大于裂隙倾角的影响;预制裂隙的偏心距是影响试样劈裂破坏的主控因素,随着偏心距的增大,劈裂主破坏外的横向和竖向次生破坏越少,破坏模式越简单,可分为“Z”字型、“一”字型和中心劈裂破坏3类;拉伸应力诱使试样产生劈裂主破坏和竖向次生破坏,而横向次生破坏则由压缩应力诱发,且偏心距越小,预制裂隙尖端的应力集中对劈裂破坏的影响越显著。In order to explore the mechanism of eccentric cracks influence on the tensile mechanical properties of rock,some rock⁃like samples containing pre⁃crack with different eccentric distances and dip angles are prepared by a self⁃designed processing device.The flattened Brazilian splitting test and non⁃contact full⁃field strain monitoring test on these rock⁃like samples are carried out.Based on the load⁃dis⁃placement curve and strain field evolution characteristics,the effects of eccentric distances and dip angles of pre⁃crack on deformation,tensile strength and splitting failure are analyzed to reveal the deterioration law of tensile strength and the causes of splitting failure.The results show that the surface strain of the sample is basically unchanged in the compression and approximate linear elastic deformation stages,which changes from slow increase to sharp increase occurring in the stable and unstable crack propagation stages.Under the same crack dip angles,the tensile strength of the rock⁃like samples contai⁃ning eccentric pre⁃crack increases with the increase of the eccentric distance.In addition,the effect of the eccentric distances on the deterioration of tensile strength is much greater than that of the crack dip angles.The eccentricity of prefabricated cracks is the main control factor affecting the splitting failure of the sample.With the increase of eccentric distance,the less horizontal and vertical secondary damage and failure outside the main damage and failure,and the simpler the failure mode,which can be classi⁃fied into three types:Z⁃shaped,one⁃shaped and central splitting failure.The tensile stress induces the splitting main failure and the vertical secondary failure,while the horizontal secondary failure is induced by the compressive stress.Moreover,the smaller the eccentric distance,the more significant the effect of stress concentration on the tip of the pre⁃crack on the splitting failure.

关 键 词：偏心裂隙 应变演化 抗拉强度 劈裂破坏 破坏模式 裂隙倾角 

分 类 号：TU45[建筑科学—岩土工程]