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Rock Mechanics Bulletin 2024年第2期3卷 78-86页

作者： Qingsheng Bai Max Friedel heinz konietzky Geotechnical Institute TU Bergakademie FreibergGustav-Zeuner-Straße 109599 FreibergGermany

This study investigates the impact of intermediate(σ_(2))and minimum(σ_(3))principal stress unloading on damage behavior and the confining pressure influence on crack initiation stress(σci)in true triaxial stress conditions,utilizing large-scale cubic *** distinct true triaxial tests were executed,examining the effects of confining stress(σ_(2)andσ_(3))unloading on porous sandstone damage and the correlation between confining stress andσ*** emission(AE)parameters,signal characteristics,and wave velocity variations were utilized to elucidate cracking mechanisms and damage development in the *** tests reveal consistent ve-locities in three orthogonal directions(V_(11),V_(22),and V_(33))during the initial two unloading *** the subse-quent three stages,confining stress unloading leads to a decrease in wave velocity in the corresponding direction,while velocities in the other two directions remain nearly ***,σ_(2)unloading generates higher amplitude AE signals compared toσ_(3)unloading,with over 70%of the micro-cracks categorized as *** the incremental loading tests,σ_(ci) is found to be contingent on confining pressure,withσ_(2)playing a crucial ***σ_(1) loading,V_(33) decreases,indicating additional crack formation;conversely,σ_(3)loading results in V33 increase,signifying the continuous closure of existing *** of the experiments are summarized and prospects in this domain are outlined.

关键词： Stress unloading Damage behavior True triaxial stress environments Wave velocity Crack initiation stress

Numerical simulation of flooding induced uplift for abandoned coal mines:simulation schemes and parameter sensitivity

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International Journal of Coal Science & Technology 2021年第6期8卷 1238-1249页

作者： Jian Zhao heinz konietzky Martin Herbst Roy Morgenstern Geotechnical Institute TU Bergakademie FreibergGustav-Zeuner-Straβe 109599 FreibergGermany

Numerical simulation approaches have been widely applied to study mining induced subsidence,and they are potential methods to study the flooding induced uplift for abandoned *** paper gives an overview about different numerical approaches to simulate uplift induced by flooding abandoned underground mines,including three different hydraulic conditions,considering both unconfined and confined water *** basic simulation schemes using 1-dimensional rock column models verified by analytical solutions demonstrate these *** results reveal that flooding induced uplift is mainly related to the pore pressure in the mine *** parameter study documents that height and stiffness of the mine goaf have the strongest influence on maximum surface uplift.

关键词： Surface uplift Abandoned mine flooding Numerical simulation Analytical solution Parameter sensitivity

Mechanical behaviour of medium-grained sandstones exposed to differential cyclic loading with distinct loading and unloading rates

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第6期14卷 1849-1871页

作者： Zhengyang Song heinz konietzky Yunfeng Wu Kun Du Xin Cai Department of Civil Engineering School of Civil and Resource Engineering University of Science and Technology Beijing Geotechnical Institute TU Bergakademie Freiberg School of Resources and Safety Engineering Central South University

This work aims to investigate the mechanical behaviour of medium-grained sandstones under cyclic loading with different loading/unloading rates. This type of cyclic loading is called differential cyclic loading(DCL) and is considered for testing rock behaviour. In the experiments, constant amplitude and multi-level cyclic loadings were performed. Three loading modes were designed to consider different relationships between loading and unloading rates. Axial strain evolution and energy dissipation were analysed for different loading/unloading rates and maximum cyclic load level. The correlations between P-wave velocities and strengths of rocks deduced from this research are compared with existing published data. The relationships between final strength and axial strain at failure under different loading patterns were also discussed and a rough assessment of the remaining fatigue life is introduced using the predicted value by fitting the axial peak strain.

关键词： Differential cyclic loading (DCL) Rock fatigue Loading/unloading rate Energy dissipation Damage accumulation

含层理构造的非均质片麻岩巴西劈裂试验及离散单元法数值模拟研究

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岩石力学与工程学报 2014年第5期33卷 938-946页

作者：谭鑫 heinz konietzky 湖南大学土木工程学院湖南长沙410082 弗莱贝格工业大学岩土工程系

为了研究岩石各向异性及非均质性对其破坏形式的影响,对含层理构造的非均质片麻岩进行了多组加载角度的巴西劈裂试验,获得不同层理方向片麻岩试件"抗拉强度"。其计算"抗拉强度"随着层理方向与加载方向夹角减小而迅速减小,当层理方向平... 详细信息

为了研究岩石各向异性及非均质性对其破坏形式的影响,对含层理构造的非均质片麻岩进行了多组加载角度的巴西劈裂试验,获得不同层理方向片麻岩试件"抗拉强度"。其计算"抗拉强度"随着层理方向与加载方向夹角减小而迅速减小,当层理方向平行于加载方向时,计算"抗拉强度"可认为是片麻岩软弱层理面间的抗拉强度;当层理方向垂直于加载方向时,计算"抗拉强度"可认为是片麻岩岩石矿物基质的等效抗拉强度;当层理方向与加载方向夹角小于90°时,则属于拉–剪复合破坏形式,是片麻岩各向异性和非均质性共同作用的结果,此时对计算"抗拉强度"的应用需要特别谨慎。用UDEC程序建立离散单元数值模型,利用随机分布的条状块体集合,通过设置层理界面和矿物颗粒之间的接触参数,模拟层理构造对片麻岩破坏的影响。数值模拟与试验结果吻合较好,解释了劈裂破坏形式产生的机制,揭示岩石在荷载状态下的破裂过程是裂纹从萌生初期的无序分布,到受微观构造影响而有序集中的自组织过程。

关键词：岩石力学巴西劈裂试验各向异性非均质性离散单元法数值模拟层理构造

Effect of heterogeneity on mechanical and micro-seismic behaviors of sandstone subjected to multi-level cyclic loading: A discrete element method investigation

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第10期15卷 2556-2581页

作者： Zhengyang Song Zhen Yang Min Zhang Fei Wang Martin Herbst heinz konietzky Joint National-Local Engineering Research Centre for Safe and Precise Coal Mining Anhui University of Science and TechnologyHuainan232000China Department of Civil Engineering University of Science and Technology BeijingBeijing100083China Geotechnical Institute TU Bergakademie FreibergFreiberg09599Germany Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines Northeastern UniversityShenyang110819China

In numerical simulation of the mechanical responses and acoustic emission(AE)characteristics of rocks under cyclic loading,the impacts of compositional heterogeneities of mineral grains have barely been *** will lead to a poor reproduction of rock’s behaviors in terms of stress-strain relationship and micro-seismic characteristics in numerical *** work aims to analyze and reveal the impact of parameter heterogeneity on the rock’s fatigue and micro-seismic properties based on *** distribution patterns(uniform and Weibull distributions),are implemented to assign four critical parameters(*** strength,cohesion,parallel bond stiffness and linear stiffness)for 32 sets of numerical *** results show that the models with high heterogeneity of tensile strength and cohesion can better reproduce the stress-strain relationship as well as the patterns of cumulative AE counts and energy *** evolution of the proportion of three-level AE events in the laboratory test is consistent with the numerical results when the highly heterogeneous tensile strength and cohesion are *** numerical results can provide practical guidance to the PFC-based modeling of rock heterogeneity when exposed to multi-level cyclic loading and AE monitoring.

关键词： Discrete element method(DEM) Heterogeneity Weibull distribution PFC3D Cyclic loading Acoustic emission(AE)

Shear strength behavior of geotextile/geomembrane interfaces

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Journal of Rock Mechanics and Geotechnical Engineering 2015年第6期7卷 638-645页

作者： Belén M.Bacas Jorge Caizal heinz konietzky Terrasolum S.L.Geotechnical Engineering Technology Development Center of University of Cantabria(CDTUC) School of Civil Engineering University of Cantabria Geotechnical Institute TU Bergakademie Freiberg

This paper aims to study the shear interaction mechanism of one of the critical geosynthetic interfaces,the geotextile/geomembrane, typically used for lined containment facilities such as landfills. A largedirect shear machine is used to carry out 90 geosynthetic interface tests. The test results show a strainsoftening behavior with a very small dilatancy （〈0.5 mm） and nonlinear failure envelopes at a normalstress range of 25e450 kPa. The influences of the micro-level structure of these geosynthetics on themacro-level interface shear behavior are discussed in detail. This study has generated several practicalrecommendations to help professionals to choose what materials are more adequate. From the threegeotextiles tested, the thermally bonded monofilament exhibits the best interface shear strength underhigh normal stress. For low normal stress, however, needle-punched monofilaments are *** the regular textured geomembranes tested, the space between the asperities is an important *** closer these asperities are, the better the result achieves. For the irregular textured geomembranestested, the nonwoven geotextiles made of monofilaments produce the largest interface shear strength.

关键词： Geotextiles Geomembranes Landfills Fiber length Roughness Shear strength Friction angle

Dynamic compressive strength and failure mechanisms of microwave damaged sandstone subjected to intermediate loading rate

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Transactions of Nonferrous Metals Society of China 2022年第11期32卷 3714-3730页

作者： Pin WANG Tu-bing YIN Xi-bing LI heinz konietzky School of Resources and Safety Engineering Central South UniversityChangsha 410083China Geotechnical Institute TU Bergakademie FreibergFreiberg09596Germany

To investigate the influence of microwave heating on the dynamic behavior and failure mechanisms of rock,dynamic compression tests were conducted on microwave-irradiated sandstone specimens using a modified split Hopkinson pressure bar(SHPB)*** results show that microwave radiation can effectively weaken the compressive strength of *** specimens show three different failure modes under impact load:tensile failure,tensile−shear composite failure and compressive−shear *** dynamic Poisson’s ratio,calculated using the measured P-and S-wave velocities,is introduced to describe the deformation characteristics of *** the increase in microwave power and heating time,the Poisson’s ratio declines first and then increases slightly,and the turning point occurs at 244.6℃.Moreover,the microstructural characteristics reveal that microwave radiation produces dehydration,pore expansion,and cracking of the *** damage mechanisms caused by microwave radiation are discussed based on thermal stress and steam pressure inside the rock,which provides a reasonable explanation for the experimental results.

关键词： sandstone microwave radiation thermal cracking dynamic compressive strength failure patterns split Hopkinson pressure bar

基于离散元方法对走滑拉分盆地演化及次级断裂扩展过程研究

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地质力学学报 2019年第5期25卷 840-852页

作者：刘源 konietzky heinz 长安大学地球科学与资源学院陕西西安710054 Geotechnical Institute TU Bergakademie FreibergFreiberg 09599Germany

拉分盆地是一种与走滑断裂带密切相关的特殊拉张构造,因其重要的构造意义,及其与火山活动、中小地震群集、特殊的成矿作用间的伴生关系而受到研究者的高度重视。关于拉分盆地的形成演化过程,已有较多的研究成果,但是由于研究手段的限制... 详细信息

拉分盆地是一种与走滑断裂带密切相关的特殊拉张构造,因其重要的构造意义,及其与火山活动、中小地震群集、特殊的成矿作用间的伴生关系而受到研究者的高度重视。关于拉分盆地的形成演化过程,已有较多的研究成果,但是由于研究手段的限制,缺少对盆地演化中次级断裂扩展过程的研究。基于离散元的数值计算方法是研究断裂扩展方式的理想方法。本文采用基于离散元的颗粒流方法,揭示纯走滑拉分盆地发育过程中的断裂扩展和连接过程,为拉分盆地演化机理和断裂扩展提供新的研究方法。同时,根据主走滑断层与块体运动方向的夹角不同,建立不同的张扭性拉分盆地模型,系统研究张扭性盆地的断裂扩展和演化机理。将上述理论研究结果与死海盆地等经典拉分盆地实例相结合,探讨了死海盆地、土耳其Cinarcik盆地、哥伦比亚ElParaiso盆地等的形成演化机理和断裂扩展方式。

关键词：数值模拟拉分盆地张扭性盆地断裂扩展离散元方法

Numerical modeling to investigate slopes and mass flow phenomena

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Global Geology 2006年第2期9卷 180-188页

作者： heinz konietzky Lei NIE Youhong SUN Technical University Bergakademie Freiberg Freiberg 09596 Germany College of Construction Engineering Jilin University Changchun 130026 China

An overview is given about up-to-date techniques for slope stability and deformation analysis as well as mass flow phenomena *** paper concentrates on a few aspects in respect to the use of numerical modeling techniques,especially in relation to the shear strength reduction techniques,discontinuum modeling,probabilistic concepts,the combination of GIS and numerical modeling as well as sophisticated hydro-mechanical coupling with time-dependent material *** present these topics are preferred topics of scientific and technical research.

关键词： discontinuum approaches numerical modeling GIS probabilistic concepts

Physical and mechanical properties of Beishan granite after different high temperature treatments

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Journal of Central South University 2022年第6期29卷 1957-1972页

作者： WANG Zi-hui ZHOU Hong-wei heinz konietzky LI Shu-min WANG Ting-zheng State Key Laboratory of Mining Disaster Prevention and Control Cofounded by Shandong Province and the Ministry of Science and Technology Shandong University of Science and TechnologyQingdao 266590China College of Energy and Mining Engineering Shandong University of Science and TechnologyQingdao 266590China School of Energy and Mining Engineering China University of Mining and TechnologyBeijing 100083China Geotechnical Institute TU Bergakademie FreibergGustav-Zeuner-Str.109596 FreibergGermany Jinan Engineering Polytechnic Jinan 250200China China Construction Eighth Engineering Division Corp.Ltd.Construction Branch Qingdao 266100China

In China,Beishan granite is chosen as a potential host surrounding rock of a high-level radioactive waste(HLW)*** this research,Beishan granite specimens were heated up to 300℃,400℃ and 500℃,*** conventional triaxial compression tests were conducted after cooling down the *** results show that after 300℃,400℃ and 500℃ heating treatment,the diameter of samples increases by 0.066%,0.143%and 0.409%,respectively,which is a little larger than the axial length *** tests show that peak strength increases slightly with increasing ***,the dilatancy threshold is lower than that observed for samples which have not experienced heating *** strain and dilatancy threshold strain show a strong temperature *** higher the temperature,the greater the ***,increasing temperature has negative influence on threshold elastic modulus E_(c) and tangent elastic modulus E_(t).Poisson ratio decreases when temperature increases from 300℃ to 500℃,but it is still larger than that observed for samples which have not experienced heating *** addition,AE monitoring shows a quiet period in the initial loading stage,which proves that the micro cracks are closed during heating and contribute to the increase of peak strength.

关键词： Beishan granite heating treatment deformation thermo-mechanical properties acoustic emission