In this paper, a discontinuous numerical model, namely SDDARF3D(three-dimensional spherical discontinuous deformation analysis for rock failure), is proposed for simulating the whole process of rock failure. Firstly, ...In this paper, a discontinuous numerical model, namely SDDARF3D(three-dimensional spherical discontinuous deformation analysis for rock failure), is proposed for simulating the whole process of rock failure. Firstly, within the framework of the classical discontinuous deformation analysis(DDA) method, the formulation of three-dimensional spherical DDA(3D SDDA) is deduced; secondly, a bonding and cracking algorithm is constructed and the SDDARF3 D model is proposed; thirdly, corresponding VC++ calculation code is developed and some verification examples are calculated. The simulated results can intuitively reproduce the failure phenomena of rock mass, indicating that the proposed SDDARF3 D numerical model is correct and effective.展开更多
Through investigating and comparing the mechanical behavior of an as-rolled Mg-3%Al-1%Zn(wt%)alloy before and after annealing treatments,it was revealed that the formation of annealing-tailored bimodal grain structure...Through investigating and comparing the mechanical behavior of an as-rolled Mg-3%Al-1%Zn(wt%)alloy before and after annealing treatments,it was revealed that the formation of annealing-tailored bimodal grain structure ensured the 330℃/4 h samples having a good combination of tensile strength and plasticity.Failure analysis demonstrated that for the as-rolled and 330℃/1 h samples with fine grain structure,their plastic deformation was mainly attributed to basal slips,whereas the deformation mechanism in the bimodal grain-structured samples was dominated by basal slips in fine grains and twinning in coarse grains.For the 330℃/8 h samples with coarse grain structure,high densities of twins were activated.Meanwhile,basal slips occurred in the twinned and un-twinned areas of coarse grains and could pass through twin boundaries.For differently treated samples,cracking preferentially occurred along slip bands,resulting in their transgranular fractures.展开更多
To analyze and predict the mechanical behaviors of deep hard rocks,some key issues concerning rock fracturing mechanics for deep hard rock excavations are discussed.First,a series of apparatuses and methods have been ...To analyze and predict the mechanical behaviors of deep hard rocks,some key issues concerning rock fracturing mechanics for deep hard rock excavations are discussed.First,a series of apparatuses and methods have been developed to test the mechanical properties and fracturing behaviors of hard rocks under high true triaxial stress paths.Evolution mechanisms of stress-induced disasters in deep hard rock excavations,such as spalling,deep cracking,massive roof collapse,large deformation and rockbursts,have been recognized.The analytical theory for the fracturing process of hard rock masses,including the three-dimensional failure criterion,stress-induced mechanical model,fracturing degree index,energy release index and numerical method,has been established.The cracking-restraint method is developed for mitigating or controlling rock spalling,deep cracking and massive collapse of deep hard rocks.An energy-controlled method is also proposed for the prevention of rockbursts.Finally,two typical cases are used to illustrate the application of the proposed methodology in the Baihetan caverns and Bayu tunnels of China.展开更多
基金supported by the Key Research Program of the Chinese Academy of Sciences(Grant No.KZZD-EW-05-03)the National Basic Research Program of China("973"Project)(Grant No.2011CB710602)the National Natural Science Foundation of China(Grant Nos.51139004&40972201)
文摘In this paper, a discontinuous numerical model, namely SDDARF3D(three-dimensional spherical discontinuous deformation analysis for rock failure), is proposed for simulating the whole process of rock failure. Firstly, within the framework of the classical discontinuous deformation analysis(DDA) method, the formulation of three-dimensional spherical DDA(3D SDDA) is deduced; secondly, a bonding and cracking algorithm is constructed and the SDDARF3 D model is proposed; thirdly, corresponding VC++ calculation code is developed and some verification examples are calculated. The simulated results can intuitively reproduce the failure phenomena of rock mass, indicating that the proposed SDDARF3 D numerical model is correct and effective.
基金supported financially by the Project from the Strategic New Industry Development Special Foundation of Shenzhen (No.JCYJ20170306141749970)National Natural Science Foundation of China Projects under Grant [Nos.51871211 and 51701129]+2 种基金the funds of International Joint Laboratory for Light Alloys,the National Key Research and Development Program of China under Grant [No.2017YFB0702001]Liaoning BaiQianWan Talents Programthe Innovation Fund of Institute of Metal Research (IMR),Chinese Academy of Sciences (CAS)
文摘Through investigating and comparing the mechanical behavior of an as-rolled Mg-3%Al-1%Zn(wt%)alloy before and after annealing treatments,it was revealed that the formation of annealing-tailored bimodal grain structure ensured the 330℃/4 h samples having a good combination of tensile strength and plasticity.Failure analysis demonstrated that for the as-rolled and 330℃/1 h samples with fine grain structure,their plastic deformation was mainly attributed to basal slips,whereas the deformation mechanism in the bimodal grain-structured samples was dominated by basal slips in fine grains and twinning in coarse grains.For the 330℃/8 h samples with coarse grain structure,high densities of twins were activated.Meanwhile,basal slips occurred in the twinned and un-twinned areas of coarse grains and could pass through twin boundaries.For differently treated samples,cracking preferentially occurred along slip bands,resulting in their transgranular fractures.
基金financial support from the National Natural Science Foundation of China(Grant Nos.51839003 and 41827806)Liaoning Revitalization Talents Program of China(Grant No.XLYCYSZX1902)。
文摘To analyze and predict the mechanical behaviors of deep hard rocks,some key issues concerning rock fracturing mechanics for deep hard rock excavations are discussed.First,a series of apparatuses and methods have been developed to test the mechanical properties and fracturing behaviors of hard rocks under high true triaxial stress paths.Evolution mechanisms of stress-induced disasters in deep hard rock excavations,such as spalling,deep cracking,massive roof collapse,large deformation and rockbursts,have been recognized.The analytical theory for the fracturing process of hard rock masses,including the three-dimensional failure criterion,stress-induced mechanical model,fracturing degree index,energy release index and numerical method,has been established.The cracking-restraint method is developed for mitigating or controlling rock spalling,deep cracking and massive collapse of deep hard rocks.An energy-controlled method is also proposed for the prevention of rockbursts.Finally,two typical cases are used to illustrate the application of the proposed methodology in the Baihetan caverns and Bayu tunnels of China.
