摘要
为了分析层状页岩巴西劈裂力学行为,开展龙马溪页岩巴西劈裂试验,采用全局嵌入零厚度黏聚单元法,建立层状页岩巴西圆盘二维有限元模型,对比数值模拟与巴西劈裂试验结果,并分析层理间距和强度对层状页岩巴西劈裂力学行为及破坏模式的影响。研究结果表明:数值模拟和试验得到的巴西劈裂强度和破坏模式吻合较好,两者的最大相对误差低于10%。数值模拟和试验得到的页岩巴西劈裂强度各向异性比分别为2.18和2.00,说明龙马溪页岩各向异性特征显著。巴西劈裂强度和破坏模式对层理面加载角度具有较强的依赖性,随着加载角度增加,巴西劈裂强度大致呈现出线性增长趋势,巴西圆盘破坏模式先由沿层理面的拉伸破坏转变为沿层理面和基质的拉伸-剪切复合破坏,再转变为沿基质的拉伸破坏。层理强度是影响巴西圆盘力学行为的关键因素:低层理强度导致巴西劈裂强度大幅降低,破坏模式主要受层理强度控制,主要产生沿层理面的拉伸或剪切破坏;高层理强度导致巴西劈裂强度大幅增加,破坏模式主要受基质强度控制,主要产生岩石基质拉伸或拉伸-剪切复合破坏。研究结果可为油气开采、采矿、隧道、边坡及地下工程的设计和施工提供依据和参考。
In order to analyse the mechanical behaviours of the Brazilian splitting of layered shale,the Brazilian splitting tests were carried out on the Longmaxi shale.A two-dimensional finite element model of the Brazilian disc(BD)of layered shale was established using the globally embedded zero-thickness cohesive element method.The numerical simulation and the Brazilian splitting testing results were then compared.The effects of bedding spacing and bedding strength on the mechanical behaviours and failure modes of the BD specimen of layered shale were analysed.The results indicate that the Brazilian splitting strength and failure modes obtained by numerical simulation and experiment are in good agreement,with the maximum error in the Brazilian splitting strength being lower than 10%.The anisotropy ratios of Brazilian splitting strength obtained by numerical simulation and experiment are 2.18 and 2.00,respectively,which indicates that the anisotropy characteristics of Longmaxi shale are significant.The Brazilian splitting strength and failure mode are significantly influenced by the loading angle of the bedding plane.As the loading angle increases,the Brazilian splitting strength exhibits a linear increase trend.The failure mode of the Brazilian disc undergoes a transition from tensile failure along the bedding plane to tensile-shear mixed failure along the bedding plane and the matrix,and subsequently to tensile failure along the matrix.The bedding strength is a crucial factor influencing the mechanical behaviours of the Brazilian disc.The low bedding strength leads to a notable decline in the Brazilian splitting strength,with the failure mode primarily determined by bedding strength,which predominantly results in tensile or shear failure along the bedding surface.The high bedding strength results in a significant increase in the Brazilian splitting strength,with the failure mode primarily determined by matrix strength,which predominantly causes tensile or tensile-shear mixed failure along the rock matrix.The findings of the research may serve as a foundation for the design and construction of oil and gas extraction,mining,tunnelling,slope,and underground engineering projects.
作者
马天寿
王浩男
FADHEL A M
刘阳
MA Tianshou;WANG Haonan;FADHEL A M;LIU Yang(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,China;MOE Key Laboratory of Oil&Gas Equipment,Southwest Petroleum University,Chengdu 610500,China)
出处
《中南大学学报(自然科学版)》
北大核心
2025年第2期702-715,共14页
Journal of Central South University:Science and Technology
基金
四川省自然科学基金资助项目(2024NSFSC0023)
四川省科技计划项目(2020JDJQ0055)。
关键词
层状页岩
巴西劈裂
各向异性
黏聚单元
层理面
破坏模式
layered shale
Brazilian splitting
anisotropy
cohesive element
bedding plane
failure mode
