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Earthquake Engineering and Engineering Vibration 2014年第2期13卷 215-222页

作者： Liu Shi Xu Jinyu Lv Xiaocong Department of Airfi eld and Building Engineering Air Force Engineering University College of Mechanics and Civil Architecture Northwest Polytechnic University

In order to investigate the dynamic mechanical properties of amphibolite and sericite-quartz schist under confi ning pressure, two rocks are subjected to impact loadings with different strain rates and confi ning pressures by using split Hopkinson pressure bar equipment with a confi ning pressure device. Based on the experimental results, the stress-strain curves are analyzed and the effects of confi ning pressure and strain rates on the dynamic compressive strength, peak strain and failure mode are summarized. The results show that:(1) The characteristics of two rocks in the ascent stage of the stressstrain curve are basically the same, but in the descent stage, the rocks gradually show plastic deformation characteristics as the confi ning pressure increases.(2) The dynamic compressive strength and peak strain of two rocks increase as the strain rate increases and the confi ning pressure effects are obvious.(3) Due to the effect of confi ning pressure, the normal stress on the damage surface of the rock increases correspondingly, the bearing capacity of the crack friction exceeds the material cohesion and the slippage of the fractured rock is controlled, which all lead to the compression and shear failure mode of rock. The theoretical analysis and experimental methods to study the dynamic failure mode and other related characteristics of rock are useful in developing standards for engineering practice.

关键词： rock mechanics SHPB with confi ning pressure device confi ning pressure strain rate impact loading

SEMI-ELLIPTIC SURFACE CRACK IN AN ELASTIC SOLID WITH FINITE SIZE UNDER impact loading

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Acta Mechanica Solida Sinica 2006年第2期19卷 122-127页

作者： Guo Ruiping Liu Guanting Fan Tianyou Academy of Equipment Command and Technology Beijing 101416 China Department of Mathematics Inner Mongolia Normal University Huhhot 010022 China Department of Physics Beijing Institute of Technology Beijing 100081 China

In this paper a semi-elliptic surface crack problem in an elastic solid of finite size under impact loading is investigated. An analysis is performed by means of fracture dynamics and the finite element method, and a three-dimensional finite element program is developed to compute the dynamic stress intensity factor. The results reveal that the effects of the solid＇s boundary surface, crack surface, material inertia and stress wave interactions play significant roles in dynamic fracture.

关键词： surface crack solid of finite size impact loading dynamic stress intensity factor,finite element method

Reinforcing effects of polypropylene on energy absorption and fracturing of cement-based tailings backfill under impact loading

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International Journal of Minerals,Metallurgy and Materials 2024年第4期31卷 650-664页

作者： Jiajian Li Shuai Cao Erol Yilmaz School of Civil and Resources Engineering University of Science and Technology BeijingBeijing 100083China State Key Laboratory of High-Efficient Mining and Safety of Metal Mines of Ministry of Education University of Science and Technology BeijingBeijing 100083China Department of Civil Engineering Geotechnical DivisionRecep Tayyip Erdogan UniversityFenerRize TR53100Turkey

Polypropylene(PP)fiber-reinforced cement-based tailings backfill(FRCTB)is a green compound material with superior crack resistance and has good prospects for application in underground ***,FRCTB exhibits susceptibility to dynamic events,such as impact ground pressure and blast *** paper investigates the energy and crack distribution behavior of FRCTB under dynamic impact,considering the height/diameter(H/D)*** Hopkinson pressure bar,industrial computed tomography scan,and scanning electron microscopy(SEM)experiments were carried out on six types of *** outcomes confirmed fiber aggregation at the bottom of *** H/D was less than 0.8,the proportion of PP fibers distributed along theθangle direction of80°-90°*** the total energy,all samples presented similar energy absorption,reflectance,and ***,a rise in H/D may cause a rise in the energy absorption rate of FRCTB during the peak phase.A positive correlation existed between the average strain rate and absorbed energy per unit *** increase in H/D resulted in a decreased crack volume fraction of *** the H/D was greater than or equal to 0.7,the maximum crack volume fraction of FRCTB was observed close to the incidence *** cracks were present only in the FRCTB with an H/D ratio of *** with H/D ratios of 0.5 and 0.6 showed similar distributions of weakly and heavily damaged *** fibers can limit the emergence and expansion of cracks by influencing their *** observations revealed considerable differences in the bonding strengths between fibers and the *** that adhered particularly well to the substrate were attracted together with the hydration products adhering to *** results show that FRCTB is promising as a sustainable and green backfill for determining the design properties of mining with backfill.

关键词： cement-based tailings fiber-reinforced backfills fracture energy absorption impact loading

Effect of roughness on the shear behavior of rock joints subjected to impact loading

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第2期15卷 339-349页

作者： Feili Wang Shuhong Wang Wei Yao Xing Li Fanzheng Meng Kaiwen Xia College of Science Qingdao University of TechnologyQingdao266033China School of Resource and Civil Engineering Northeastern UniversityShenyang110819China State Key Laboratory of Hydraulic Engineering Simulation and Safety School of Civil EngineeringTianjin UniversityTianjin300072China Department of Civil and Mineral Engineering University of TorontoTorontoOntarioM5S 1A4Canada

The shear behavior is regarded as the dominant property of rock joints and is dramatically affected by the joint surface *** date,the effect of surface roughness on the shear behavior of rock joints under static or cyclic loading conditions has been extensively studied,but such effect under impact loading conditions keeps *** address this issue,a series of impact shear tests was performed using a novel-designed dynamic experimental system combined with the digital image correlation(DIC)*** dynamic shear strength,deformability and failure mode of the jointed specimens with various joint roughness coefficients(JRC)are comprehensively *** show that the shear strength and shear displacement characteristics of the rock joint under the impact loading keep consistent with those under static loading ***,the temporal variations of shear stress,slip displacement and normal displacement under the impact loading conditions show obviously different *** elastic rebound of the slip displacement occurs during the impact shearing and its value increases with increasing joint *** identifiable stages(*** and dilation)are observed in the normal displacement curves for the rougher rock joints,whereas the joints with small roughness only manifest normal compression ***,as the roughness increases,the maximum compression tends to decrease,while the maximum dilation gradually ***-over,the microstructural analysis based on scanning electron microscope(SEM)suggests that the roughness significantly affects the characteristics of the shear fractured zone enclosing the joint surface.

关键词： Rock joint impact loading Joint roughness Shear strength Shear deformability

Dynamic response characteristics of dry and watersaturated schist under impact loading

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Journal of Mountain Science 2020年第12期17卷 3123-3136页

作者： ZHOU Yang SU Sheng-rui CHEN Jian-xun School of Geological Engineering and Geomatics Chang’an UniversityXi’an 710064China School of Highway Chang’an UniversityXi’an 710064China

Many geological engineering hazards are closely related to the dynamic mechanical properties of rock ***,most existing studies on the dynamic mechanical properties of rock materials were conducted on the hard rocks such as sandstone,granite,limestone,and marble,whereas soft rocks,such as schist,are less ***,in this study,a series of triaxial impact tests were conducted on dry and saturated schist by employing a modified triaxial split Hopkinson pressure bar system to reveal the coupling effects of water,strain rate,and triaxial confining pressure on the mechanical properties of *** results show that schist is a type of watersensitive rock and the stress-strain curve of saturated schist has apparent *** effects of strain rate on dynamic strain,deformation modulus and peak stress were *** results also show that the dynamic peak stress is affected by the combined softening effect and viscous effect of water under impact ***,it was found that the failure mode of schist belongs to typical axial tensile failure under uniaxial impact tests,and shear failure is the main failure mode under triaxial impact *** the increase in confining pressure,the failure modes of schist change from tensile failure to shear *** research can provide useful parameters for geological engineering hazard prevention in mountain areas.

关键词： Dry and water-saturated schist Triaxial stress constraint Modified triaxial split Hopkinson pressure bar Dynamic mechanical behavior impact loading

Responses of jointed rock masses subjected to impact loading

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Journal of Rock Mechanics and Geotechnical Engineering 2018年第4期10卷 624-634页

作者： Shabnam Aziznejad Kamran Esmaieli John Hadjigeorgiou Denis Labrie Lassonde Institute of Mining University of Toronto CanmetMINING Natural Resources Canada

impact-induced damage to jointed rock masses has important consequences in various mining and civil engineering applications. This paper reports a numerical investigation to address the responses of jointed rock masses subjected to impact loading. It also focuses on the static and dynamic properties of an intact rock derived from a series of laboratory tests on meta-sandstone samples from a quarry in Nova Scotia, Canada. A distinct element code(PFC2D) was used to generate a bonded particle model(BPM) to simulate both the static and dynamic properties of the intact rock. The calibrated BPM was then used to construct large-scale jointed rock mass samples by incorporating discrete joint networks of multiple joint intensities into the intact rock matrix represented by the BPM. Finally, the impact-induced damage inflicted by a rigid projectile particle on the jointed rock mass samples was determined through the use of the numerical model. The simulation results show that joints play an important role in the impactinduced rock mass damage where higher joint intensity results in more damage to the rock mass. This is mainly attributed to variations of stress wave propagation in jointed rock masses as compared to intact rock devoid of joints.

关键词： Jointed rock mass impact loading Microcracks Rock damage

Crack dynamic propagation properties and arrest mechanism under impact loading

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第6期12卷 1171-1184页

作者： Yuqing Dong Zheming Zhu Li Ren Lei Zhou Peng Ying Meng Wang State Key Laboratory of Hydraulics and Mountain River Engineering School of Architecture and EnvironmentSichuan UniversityChengdu610065China MOE Key Laboratory of Deep Earth Science and Engineering School of Architecture and EnvironmentSichuan UniversityChengdu610065China

Crack dynamic propagation and arrest behaviors have received extensive attention over the ***,there still remain many questions,*** what conditions will a running crack come to arrest?In this paper,drop weight impact(DWI)tests were conducted to investigate crack arrest mechanism using single cleavage triangle(SCT)rock *** sandstone was selected to prepare the SCT *** stress intensity factors(DSIFs)were calculated by ABAQUS code,and the critical DSIFs were determined by crack propagation speeds and fracture time measured by crack propagation gauges(CPGs).The test results show that the critical DSIF at propagation decreases with crack propagation *** simulation for SCT specimens under different loading waves was performed using AUTODYN *** reflected compressive wave from the incident and transmitted plates can induce crack arrests during propagation,and the number of arrest times increases with the wave *** order to eliminate the effect of the incident and transmitted plates,models consisting of only one SCT specimen without incident and transmitted plates were established,and the same trapezoid-shaped loading wave was applied to the SCT *** results show that for the SCT specimen with transmitted boundary(analogous to an infinite plate),the trapezoid-shaped loading wave cannot induce crack arrest *** numerical results can well describe the occurrence of crack arrest in the experiments.

关键词： Crack arrest Stress wave Fracture toughness Reflected wave impact loading

Dynamic Responses of Cellular Metal-Filled Steel Beam-Column Joint Under impact loading

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Journal of Shanghai Jiaotong university(Science) 2020年第3期25卷 384-393页

作者： DING Kewei LIU Jianhua REN Jianwei MA Wei College of Civil Engineering Anhui Jianzhu UniversityHefei 230601China Provincial Key Laboratory for Architectural Structure and Underground Engineering Anhui Jianzhu UniversityHefei 230601China

Taking the excellent energy absorption performances of cellular structures into consideration,three beam-column steel joints are proposed to analyze the effect of cellular metallic fillers on impact mechanical responses of beam-column *** on the existing experimental results,the finite element models of the associated joints are established by using finite element method *** deformation mode,the bearing capacity and energy absorption performance of various joints subjected to impact loadings with the loading velocities from 10 to 100 m/s are analyzed,*** dynamic responses of cellular metal-filled beamcolumn joints are quantitatively analyzed by means of displacements of central region,nominal impacting stress and energy absorption *** results can be concluded that the filling of cellular filler weakens the stress concentration on joints,alleviates the occurrence of tearing in connection region among column and beam,and reduces the displacement caused by impact *** absorption efficiency of filled joints subjected to impact loading increases as the impacting velocity increases,and the cellular metallic filler improves their impact resistance of beam-column *** energy absorption efficiency of fully filled joints is superior to that of *** study can provide a reference for steel structural design and post-disaster repair under extreme working conditions.

关键词： steel beam-column joint cellular metal material impact loading dynamic responses impact energy absorption

Dynamic Mechanical Properties of EPS Concrete Under impact loading

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Journal of Shanghai Jiaotong university(Science) 2019年第1期24卷 94-100页

作者： HU Jun REN Jianwei WU Deyi College of Civil Engineering Anhui Jianzhu University Provincial Key Laboratory of Building Structure and Underground Engineering of Anhui Anhui Jianzhu University

The finite element method(FEM) models of expanded polystyrene(EPS) concrete were established to study the relationships among dynamic damage, energy absorption and efficiency of buffering materials with varied flexible aggregate contents and impact speeds based on the existing split Hopkinson pressure bar(SHPB)experiments. Applied material indexes including damage degrees, crack rates and energy absorption capacities,and the dynamic responses of EPS concrete under impact loading were investigated. The results show that the failure types of these materials evolve from quasi-brittle destruction to flow-plastic destruction, the damage degree of EPS concrete increases with the enhancement of flexible aggregate content, and the peak of crack rate exists around the extreme point of shock velocities. The energy-absorption efficiency of EPS concrete increases nonlinearly when the EPS beads increase and the shock speed enhances, respectively.

关键词： EPS concrete dynamic damage crack rate energy absorption impact loading

Constitutive model for concrete subjected to impact loading

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Journal of Southeast University(English Edition) 2012年第1期28卷 79-84页

作者：刘海峰宁建国宁夏大学土木与水利工程学院银川750021 北京理工大学爆炸科学与技术国家重点实验室北京100081

To better design and analyze concrete structures, the mechanical properties of concrete subjected to impact loadings are investigated. Concrete is considered to be a two-phase composite made up of micro-cracks and solid parts which consist of coarse aggregate particles and a cement mortar matrix. The cement mortar matrix is assumed to be elastic, homogeneous and isotropic. Based on the Moil-Tanaka concept of average stress and the Eshelby equivalent inclusion theory, a dynamic constitutive model is developed to simulate the impact responses of concrete. The impact compression experiments of concrete and cement mortar are also carried out. Experimental results show that concrete and cement mortar are rate-dependent. Under the same impact velocity, the load-carrying capacity of concrete is higher than that of cement mortar. Whereas, the maximum strain of concrete is lower than that of cement mortar. Regardless of whether it is concrete or cement mortar, with the increase in the impact velocity, the fragment size of specimens after experiment decreases.

关键词： concrete micromechanics dynamic constitutivemodel impact loading