检索结果-南通市图书馆

Rate-dependent mechanical behavior of jointed rock with an impersistent joint under different infill conditions

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2022年第5期14卷 1380-1393页

作者： Sachin Kumar Gaurav Tiwari Venkitanarayanan Parameswaran Arghya Das Department of Civil Engineering Indian Institute of TechnologyKanpurIndia

Transition in the rate-dependent mechanical response of rock was investigated due to the presence of impersistent joint with different infill conditions.Four types of samples,i.***.intact,jointed with no grouting,jointed and grouted with cement,and jointed and grouted with epoxy,were fabricated using model material.A series of dynamic split Hopkinson pressure bar(SHPB) tests was conducted on prepared samples with strain rates varying between 53-130 salong with static uniaxial compression tests(10s).Progression of fracture/failure along samples was monitored using high-speed imaging and digital image correlation(DIC).Strength was observed to be significantly lower for jointed samples as compared to intact samples.However,the increasing trend of strength with strain rates remained similar for all types of samples.Epoxy was observed to be a better grout due to greater improvement in the strength of epoxy grouted jointed samples than cement grouted samples under both static and dynamic conditions.Significant changes were observed in fracture behavior(initiation,pattern and mechanism)with strain rate for intact and jointed unfilled/grouted samples.Fracturing was dominated by shear and tensile cracks at high strain rates compared to tensile cracks at low strain rates in all samples.Unlike static loading conditions,the location of cracks initiation shifts away from joint tips with increasing strain rate and depending upon existing infill conditions(unfilled/grouted).

关键词： Jointed rocks Grouted joint Dynamic loading strain rates

Analysis of recent Antarctic plate kinematics based on GNSS data

在线全文

学校读者我要写书评

暂无评论

Geodesy and Geodynamics 2023年第2期14卷 99-110页

作者： Ihor Savchyn Ivan Brusak Korneliy Tretyak Lviv Polytechnic National University Institute of GeodesyUkraine

The research aims to study recent Antarctic plate kinematics based on Global Navigation Satellite System(GNSS)data.The research covers 60 continuous GNSS stations located on the Antarctic plate during 1994-2021.We determine the components of horizontal displacement vectors of these GNSS stations and construct the schematic map of their distribution.The results indicate that the direction of velocity vectors of horizontal displacements has a rotational nature in clockwise order.The analysis of deformation processes shows that a gradual decrease in the horizontal strain rates,maximum shear strain and area strain is taking place from west to east,in the direction of West Antarctica-the Transantarctic Mountains-East Antarctica.The absolute rotation pole of the Antarctic plate in the ITRF2014/IGS14 reference frame has been determined,and the obtained values are in good agreement with recent plate models.

关键词： Continuous GNSS station Horizontal velocity strain rates Rotation pole The Antarctic plate

A strain Rate Dependent Constitutive Model for the Lower Silurian Longmaxi Formation Shale in the Fuling Gas Field of the Sichuan Basin,China

在线全文

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2019年第4期93卷 972-981页

作者： HOU Zhenkun LI Xianwen ZHANG Yanming LIANG Huqing GUO Ying CHENG Hanlie GAO Ruchao Guangzhou Institute of Building Science Co. Ltd.Guangzhou 510440China School of Materials Science and Engineering South China University of TechnologyGuangzhou 510640China Oil and Gas Technology Research Institute Changqing Oilfield Branch Company of PetroChinaXi’an 710018China Institute of Geology and Paleontology Linyi UniversityLinyi 276000ShandongChina LandOcean Energy Services Co. Ltd.Beijing 100084China CCCC Second Harbour Engineering Co. Ltd.Wuhan 430040China

Shale,as a kind of brittle rock,often exhibits different nonlinear stress-strain behavior,failure and timedependent behavior under different strain rates.To capture these features,this work conducted triaxial compression tests under axial strain rates ranging from 5×10-6 s-1 to 1×10-3 s-1.The results show that both elastic modulus and peak strength have a positive correlation relationship with strain rates.These strain rate-dependent mechanical behaviors of shale are originated from damage growth,which is described by a damage parameter.When axial strain is the same,the damage parameter is positively correlated with strain rate.When strain rate is the same,with an increase of axial strain,the damage parameter decreases firstly from an initial value(about 0.1 to 0.2),soon reaches its minimum(about 0.1),and then increases to an asymptotic value of 0.8.Based on the experimental results,taking yield stress as the cut-off point and considering damage variable evolution,a new measure of micro-mechanical strength is proposed.Based on the Lemaitre’s equivalent strain assumption and the new measure of micro-mechanical strength,a statistical strain-rate dependent damage constitutive model for shale that couples physically meaningful model parameters was established.Numerical back-calculations of these triaxial compression tests results demonstrate the ability of the model to reproduce the primary features of the strain rate dependent mechanical behavior of shale.

关键词： strain rates triaxial compression tests damage variable constitutive model Longmaxi Formation shale

Analysis of temporal and spatial variation of crustal strain around Longmenshan Fault based on GNSS observation

在线全文

学校读者我要写书评

暂无评论

Analysis of temporal and spatial variation of crustal strain...