CAJ | 학술논문

脆性大理岩的变形破裂与其内部微裂纹的扩展贯通密切相关，其宏观力学响应取决于细观结构构造；因岩石内部的封闭性，难以掌握其内部微裂纹的发育演化机制。基于三维颗粒流理论，通过引入 BPM 模型和超级单元clump技术，并依据锦屏一级地下厂房大理岩的SEM矿物成份检测结果，建立基于矿物形状的大理岩细观结构模型，在对细观力学参数敏感性分析的基础上，根据室内单轴和三轴压缩试验结果确定大理岩的细观力学参数，构建大理岩的细观力学数值模型，对不同应力状态和应力路径下大理岩的变形破裂演化及扩容孕育过程进行数值模拟分析。研究结果表明：大理岩细观力学数值模型所描述的宏观力学响应与室内试验结果具有很好的一致性；单轴或低围压时微裂纹呈缓慢-急增的指数型增长趋势，高围压时微裂纹呈缓慢-急增-缓慢的近似S型增长趋势；随着围压的增加，张拉裂纹所占比例逐渐减少，剪切裂纹所占比例逐渐增加；与相同初始围压时的加载应力路径相比，卸载应力路径下岩石峰值应力对应的轴向应变小，张拉裂纹所占比例高，且随卸载过程逐渐起主控作用，最终形成张性宏观破裂面，体现了大理岩卸荷扩容效应更为显著且脆性更强。在不同应力状态和应力路径下，张性裂纹扩展控制机制和剪切裂纹摩擦控制机制相互作用，此减彼增逐步过渡。研究结果从细观尺度上揭示锦屏一级大理岩扩容孕育机制，为正确认识和把握锦屏一级地下厂房洞室群施工期围岩大变形形成机制以及岩体卸荷破裂规律提供基础。
취성대리암적변형파렬여기내부미렬문적확전관통밀절상관，기굉관역학향응취결우세관결구구조；인암석내부적봉폐성，난이장악기내부미렬문적발육연화궤제。기우삼유과립류이론，통과인입 BPM 모형화초급단원clump기술，병의거금병일급지하엄방대리암적SEM광물성빈검측결과，건립기우광물형상적대리암세관결구모형，재대세관역학삼수민감성분석적기출상，근거실내단축화삼축압축시험결과학정대리암적세관역학삼수，구건대리암적세관역학수치모형，대불동응력상태화응력로경하대리암적변형파렬연화급확용잉육과정진행수치모의분석。연구결과표명：대리암세관역학수치모형소묘술적굉관역학향응여실내시험결과구유흔호적일치성；단축혹저위압시미렬문정완만-급증적지수형증장추세，고위압시미렬문정완만-급증-완만적근사S형증장추세；수착위압적증가，장랍렬문소점비례축점감소，전절렬문소점비례축점증가；여상동초시위압시적가재응력로경상비，사재응력로경하암석봉치응력대응적축향응변소，장랍렬문소점비례고，차수사재과정축점기주공작용，최종형성장성굉관파렬면，체현료대리암사하확용효응경위현저차취성경강。재불동응력상태화응력로경하，장성렬문확전공제궤제화전절렬문마찰공제궤제상호작용，차감피증축보과도。연구결과종세관척도상게시금병일급대리암확용잉육궤제，위정학인식화파악금병일급지하엄방동실군시공기위암대변형형성궤제이급암체사하파렬규률제공기출。
Deformation and fracture of brittle marble is closely related to the extension of internal microcracks,and the macroscopic mechanical response of marble depends on its mesoscopic structures. Because the micro cracks are sealed in rock bodies,it is very difficult to grasp the development mechanism of the internal microcracks. With the help of the three-dimensional theory of particle flow and introducing the BPM model and the technology of super unit clump,a mesoscopic structure model of marble in terms of the mineral configurations was established on the basis of the testing result of SEM on the mineral contents of marble from the underground powerhouse of Jinping I hydropower station. The mesoscopic mechanical parameters of marble based on the sensitivity analysis was determined according to the indoor testing results of the uniaxial and triaxial compression and the mesoscopic numerical model of marble was also constructed. The deformation and fracture and the expansion process of marble under different stress states and stress paths were analyzed through numerical simulations. The numerical results of the macroscopic mechanical response of marble were found to agree well with the laboratory testing results. The numbers of microcracks grew slowly initially and soon exponentially under the condition of uniaxial and low confining pressures,however,the growth curve was approximately an “S” shape under the condition of high confining pressure. As the increasing of the confining pressure,the proportion of the tensile cracks reduced gradually,and the shear cracks increased. Under the identical initial confining pressure,the axial strain at the peak strength of rock was smaller and the proportion of tensile cracks was higher in the unloading stress path than the ones in the loading stress path. The tensile cracks played the leading role in the unloading process and eventually caused the tensile macro fracture surface to be formed,indicated that the volume expansion effect of marble under unloading was more significant and the brittle characteristics was more obvious. Under the different stress states and stress paths,the control mechanism of tensile crack propagation interacted with the one of shear crack friction,one grew slowly,the other grew fast.