Mesoscopic Damage Mechanics Research Articles

Investigation on the dynamic mechanical properties and mesoscopic damage mechanism of alkali-activated seawater and sea sand concrete in marine corrosive environments

The dynamic mechanical behavior of alkali-activated seawater and sea sand concrete (ASSC) in marine corrosive environments were investigated by splitting Hopkinson pressure bar (SHPB) impact experiment. This study investigated how corrosion age, strain rate, and various corrosion environments influence the mechanical characteristics and macroscopic failure behavior of ASSC. Furthermore, a three-dimensional (3D) mesoscopic model was employed to investigate mesoscopic damage mechanism of ASSC. The outcomes indicate that increasing corrosion age intensifies the corrosion effect on concrete, with the dry-wet cycling having a more pronounced erosive impact compared to solution immersion. The dynamic mechanical properties and failure morphology exhibit a pronounced strain-rate effect. Microscopic analysis showed that cracks first developed in the interfacial transition zone (ITZ) before propagating into mortar. As smaller cracks coalesced into larger ones, their progression ultimately led to the fragmentation of the aggregates.

The Mesoscopic Damage Mechanism of Jointed Sandstone Subjected to the Action of Dry–Wet Alternating Cycles

The effect of the dry–wet cycle, characterized by periodic water level changes in the Three Gorges Reservoir, will severely degrade the bearing performance of rock formations. In order to explore the effect of the dry–wet cycle on the mesoscopic damage mechanism of jointed sandstone, a list of meso-experiments was carried out on sandstone subjected to dry–wet cycles. The pore structure, throat features and mesoscopic damage evolution of jointed sandstone with the action of the dry–wet cycle were analyzed using a-low-field nuclear magnetic resonance (NMR) technique. Subsequently, the impact on the mineral content of dry–wet cycles was studied by small angle X-ray scattering (SAXS). Based on this, the mesoscopic damage mechanism of sandstone subjected to dry–wet cycles was revealed. The results show that the effects of the drying–wetting cycle can promote the development of porous channels within sandstone, resulting in cumulative damage. Besides, with an increase in dry–wet cycles, the proportion of small pores and pore throats decreased, while the proportion of medium and large pores and pore throats increased. The combined effects of extrusion crush, tensile fracture, chemical reaction and dissolution of minerals inside the jointed sandstone contributed to the development of mesoscopic pores, resulting in the increase of porosity and permeability of rock samples under the dry–wet cycles. The results provide an important reference value for the stability evaluation of rock mass engineering under long-term dry–wet alternation.

Investigation on the evolution of concrete pore structure under freeze-thaw and fatigue loads

Hydraulic concrete structures in seasonal frozen regions serve under freeze-thaw cycles and cyclic loading conditions which cause notable alterations in the concrete pore structure and a significant reduction in the mechanical properties and durability of concrete. To understand the macroscopic and mesoscopic damage processes and mechanism of concrete subjected to freeze-thaw cycles and cyclic loading lead, the compressive experiment and computed tomography test of concrete after freeze-thaw and fatigue loading tests were conducted. And the influences of freeze-thaw cycle damage and cyclic loading damage on the pore structure of concrete were analyzed. The relationships between concrete pore fractal dimension, compressive strength, and elastic modulus were revealed. The concrete average pore size can be regarded to grows linearly under freeze-thaw and cyclic loading. The porosity, pore volume, and pore surface area increase with the increase in freeze-thaw cycles, and their relationship can be represented by a quadratic function. However, they first decrease and then increase with the increase of loading cycles after a specific freeze-thaw cycles number. Under the combined action of freeze-thaw cycles and cyclic loading, the non-uniformity degree of concrete pore distribution decreases, and the overall structure is more regular. The distribution of single pore morphology tends to be spherical and banded, respectively. The cyclic loading promotes the extension of the internal pores and cracks of freeze-thaw-damaged concrete which aggravates damage of concrete. Under freeze-thaw cyclic loading, the concrete compressive strength and elasticity modulus is linearly and positively correlated with fractal dimension. With the increase of loading cycles number after freezing and thawing, the fractal dimension and compressive strength decrease, and the elasticity modulus has a larger dispersion. The relationship model between concrete compressive strength and fractal dimension can well describe the macroscopic and mesoscopic evolution of concrete under freeze-thaw and cyclic loading. The results can provide a scientific basis for improving the design and maintenance of concrete and benefit extending the long-term service life of hydraulic concrete structures in cold climates.

Mesoscopic damage mechanism of multiple freeze–thaw cycles of cement gravel based on particle flow theory

Mesoscopic damage mechanism of multiple freeze–thaw cycles of cement gravel based on particle flow theory

Experimental and Numerical Analysis of Flexural Properties and Mesoscopic Failure Mechanism of Single-Shell Lining Concrete

Despite ongoing research efforts aimed at understanding the structural response of steel fiber reinforced concrete (SFRC), there is very limited research on the failure characteristics and mesoscopic damage mechanism of SFRC, specifically when under flexure. In this study, a four-point bending test of plain concrete (PC) and SFRC with different fiber contents is carried out to investigate the flexural performance of SFRC. The crack propagation process, cracking load, ultimate load, and load-deflection curves of PC and SFRC beams are obtained. Additionally, the discrete element method (DEM), using PFC2D 6.0 software, is adopted to explore the mesoscopic properties of PC and SFRC. The test and simulation results of PC and SFRC beams are compared and analyzed, and some conclusions are drawn. The results show that steel fiber can efficiently improve the compressive strength of concrete when the fiber content is 30 kg/m3, and significantly improve the deformation resistance, crack resistance, and flexural capacity of concrete. The refined numerical models of PC and SFRC beams are established based on compressive strength and aggregate screening results. Through the numerical four-point bending test, the mesoscopic mechanical behaviors of models reveal the damage mechanism of SFRC. The horizontally distributed steel fibers bridge both sides of the cracks to resist crack development, and the vertically distributed steel fibers guide the cracks to the place with strong contact, thus resisting crack height development. The test results show that, for flexural properties, the optimal steel fiber content of SFRC is 31 kg/m3.

Mesoscopic Damage Mechanism of Red-bed Mudstone Based on Geometric and Mechanical Representative Elementary Areas

Mesoscopic Damage Mechanism of Red-bed Mudstone Based on Geometric and Mechanical Representative Elementary Areas

Study on mechanical properties and damage mechanism of alkali-activated slag concrete

The cement industry has become one of the important sources of greenhouse gas emissions, and the alkali-activated slag (AAS) has the same mechanical properties and lower carbon emissions as cement in the production process. Therefore, it can be used as an alternative binder for low-carbon buildings. The effect of alkali concentration (mass ratio of Na2O to binder) on the macro-mechanical properties and meso-damage mechanism of alkali-activated slag concrete (AASC) under uniaxial compression was investigated in this work. Six kinds of concrete with alkali concentration of 2 %, 4 %, 6 %, 8 %, 10 % and 12 % were prepared. The microscopic characteristics of AASC were characterized by nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), x-ray diffraction (XRD) and x-ray energy dispersive spectroscopy (EDS); the meso-damage evolution mechanism of AASC was discussed by statistical damage theory. The results showed that the peak stress and elastic modulus of AASC specimens increased, and the microstructure became denser with the increase of alkali concentration. However, the mechanical properties of the specimen deteriorated to some extent when the alkali concentration exceeded 6 %; for example, the peak stress decreased by 24.00 MPa when the alkali concentration was increased from 6 % to 12 % at the age of 28d. Based on the statistical damage theory, the effective stress concept was introduced to quantitatively analyze the mesoscopic damage evolution of AASC. Both fracture and yielding damage modes were considered. By exploring the regular changes of the mesoscopic parameters, the connection between the macroscopic mechanical properties and the mesoscopic damage mechanism was established. Based on the above mechanical properties and mesoscopic damage results, the alkali concentration of 6 % can be used as the best mixture proportions of AASC.

Study on multi-scale dynamic mechanical properties of metakaolin modified recycled aggregate concrete under coupling conditions of sulfate attack and dry-wet cycles

To explore the potential of modified recycled aggregate concrete for use in construction projects, the evolution of its properties in the combined effects of environment and loading was investigated. This paper considered various factors, including the replacement amount of metakaolin (0 %, 15 %), dry-wet cycles (0, 20, 60, and 120 cycles), and the dynamic strain rate (ε˙ = 10−5/s, 10−4/s, 10−3/s, and 10−2/s), and conducted uniaxial compression, scanning electron microscopy (SEM), and X-ray diffraction (XRD) tests. The experimental findings demonstrated that the peak stress and elastic modulus of recycled aggregate concrete (RAC) exhibited a pattern of initial increase followed by a decrease before and after 20 dry-wet cycles, a concurrent upward trend was observed in both parameters with an escalation in strain rate and the incorporation of metakaolin (MK), and no uniform trend was observed for the peak strain. The test results from SEM and XRD revealed that the persistent formation of sulfate crystals and expansive substances like gypsum and ettringite were the primary factors contributing to the deterioration of specimen damage as cycle counts escalated. A quantitative analysis was conducted to investigate the mesoscopic damage mechanism associated with the dynamic mechanical properties and durability evolution process of metakaolin-based RAC under sulfate erosion. The correlation between the macroscopic mechanical properties and the microscopic changes of RAC was explored using statistical damage theory.

Study on mechanical properties and mesoscopic damage mechanism of metakaolin modified recycled aggregate concrete

This research explored the effect of water-binder ratio (w/b) and curing age on the mechanical properties, microstructure, and damage mechanism of modified recycled aggregate concrete (RAC) with metakaolin (MK). The consequence appeared that the mechanical properties of the specimens were positively correlated with curing age, but negatively correlated with w/b. In addition, the incorporation of MK increased the peak stress and peak strain of the specimens with w/b of 0.65 by an average of 17.46% and 8.42% at six ages. Through microscopic test, it was found that the mechanical properties of the specimen were related to the hydration reaction, and the continuously generated gel products made the matrix structure more compact. Based on the statistical damage theory, the influence of w/b, age and MK on the damage evolution of mesoscopic fracture and yield were quantitatively analyzed, and a correlation between macroscopic mechanical properties and the mesoscopic damage mechanism was established.

Numerical Simulation Study on the Constitutive Model of Fully-Graded Concrete Based on Statistical Damage Theory

A statistical damage model (SDM) of fully-graded concrete was created using statistical damage theory, based on the mechanical properties of axial tension and axial compression of the material. The SDM considers two damage modes, fracture and yield, and explains the intrinsic connection between the mesoscopic damage evolution mechanism and the macroscopic nonlinear mechanical behavior of fully-graded concrete. The artificial bee colony (ABC) algorithm was used to obtain the optimal parameter combination through an intelligent search of parameters εa, εh, εb and H in the constitutive model by taking the test data as the target value, and the sum of the squares of the differences between the target value and the predicted value as the objective function. The SDM numerical simulation model of fully-graded concrete is proposed by compiling subroutines in FORTRAN by constructing two modules of data model and damage analysis. The numerical results under uniaxial and biaxial forces are in agreement with the experimental results, which verifies the accuracy of the program. The model also analyzes the characteristics of mesoscopic damage evolution and predicts the mechanical properties under triaxial forces. The results show that the proposed numerical simulation model can reflect the salient features for fully-graded concrete under uniaxial, biaxial and triaxial loading conditions, and the evolution law of mesoscopic parameters. Therefore, the proposed model serves as a basis for the refined finite element analysis of hydraulic fully-graded concrete structures and reveals the mesoscopic damage mechanism of concrete under different load environments.

Method of defining rock damage variable on the basis of wave impedance

AbstractA method of determining rock damage variable from wave impedance, which is suitable for the study of dynamics, is presented. The determined variable provides a more reasonable quantitative description of the degree of rock damage. First, the Taylor model of mesoscopic damage mechanics is used to derive the relationship between the velocity of longitudinal waves and the density of rock materials. Based on the measured data of rock samples with different lithology and the same lithology, the relationship between the longitudinal wave velocity and density of rock materials is studied. It is demonstrated that using the wave impedance to define the rock damage variable has advantages over using the P‐wave velocity. Second, the relationship between the wave impedance and degree of damage to the rock material is studied using an electron microscope and ultrasonic testing technology, and the microstructure of rock samples with a wave impedance gradient and time–frequency‐domain characteristics of the ultrasonic signals are compared and analyzed. It is found that it is feasible to determine the damage degree of the rock from the wave impedance. Finally, a method of defining rock damage variable with the wave impedance is further proposed and its rationality verified. The research results show that there is a good positive correlation between the longitudinal wave velocity and density of rock materials, and there is a strong correlation between the degree of rock damage and its wave impedance. The damage variable defined by wave impedance can better reflect the damage state and damage evolution process of rock.

Study on macroscopic mechanical properties and mesoscopic damage mechanism of recycled concrete with metakaolin under sodium sulfate erosion environment

The sodium sulfate resistance of recycled concrete (RC) under dry-wet (DW) cycle was studied, and the mesoscopic damage mechanism of RC under uniaxial compression was revealed by using statistical damage theory. The substitution rate of metakaolin (MK) and the number of DW cycles were considered in the test variables. The microstructure of RC was characterized by acoustic emission (AE), scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray fluorescence spectrometer (XRF). The results showed that with the increase of the number of DW cycles, the peak stress and elastic modulus of the specimen increased at first and then decreased, and the peak strain and mass change rate tended to increase. When the cycle times extended from 0 to 120, the peak stress of MK0 increased from −37.2 MPa to −50.7 MPa and then decreased to −29.1 MPa. The deterioration degree and mechanical properties of RC were improved by adding MK. The peak stress of MK15 increased by 26.4% and 16.4% respectively when it was cycled for 0 and 120 times compared with that of MK0. Based on the statistical damage theory, it was considered that there were 2 mesoscopic damage modes of fracture and yield, and the effective stress dominated the damage evolution of specimen during the failure process. The peak state and critical state were distinguished, and the mean values of σcr/σp and εcr/εp were 0.884 and 1.392 respectively. This paper provided experimental support for improving the sulfate resistance of RC, and provided theoretical basis for the use of in erosive environments.

Study on mechanical properties and damage mechanism of recycled concrete containing silica fume in freeze–thaw environment

In order to study the uniaxial compressive mechanical properties and damage evolution of recycled aggregate concrete (RAC) containing silica fume (SF) under freeze–thaw cycles, the RAC with SF replaced partial cement was prepared. The replacement rates were 0% and 9%. The RAC were subjected to 0, 50, 75, 100, 125 freeze–thaw cycles and uniaxial compression tests. The microstructure, micro-crack propagation process and reaction products were observed by acoustic emission (AE) and scanning electron microscope (SEM). The statistical damage theory was used to explore the mesoscopic damage evolution mechanism of RAC. The results showed that the peak stress and modulus of elasticity of the specimen tended to decrease, the peak strain and mass loss rate gradually increased with the increase of the number of freeze–thaw cycles(N). The compressive strength of RAC with S = 0% decreases from −41.52MPa to −11.23MPa when N increases from 0 to 125. The addition of SF produced additional volcanic ash reactions, resulting in an increase in ettringite (AFt), which reduces the porosity of RAC and is able to increase the compressive strength at different N significantly. Compressive strength increases by 21.84% and 12.06% at N = 0 and 125, respectively. Considering the existence of two mesoscopic damage modes of fracture and yield, the deformation failure mechanism of RAC was analyzed from the perspective of effective stress. The all five characteristic parameters characterizing the mesoscopic damage show significant regular change with increase of the number of cycles. The relationship between the macroscopic mechanical properties of RAC and the mesoscopic damage mechanism was established by analyzing the evolution law for the characteristic parameters.

Numerical simulation on hydraulic fracture propagation in laminated shale based on thermo-hydro-mechanical-damage coupling model

The temperature of a deep shale reservoir may reach more than 100°C, and the effect of thermal shock on shale hydraulic fracturing has rarely not been considered in previous studies. Based on mesoscopic damage mechanics and the finite element method, a thermo-hydro-mechanical-damage (THMD) coupling model considering temperature, seepage, stress, and damage fields was constructed to investigate the effects of reservoir temperature, convective heat transfer coefficient ( h), in-situ stress difference and bedding plane angle ( αθ) on shale hydraulic fracturing. The results show that multiple hydraulic fractures (HFs) can occur under thermal shock and that HFs control the distribution of seepage, temperature, and stress fields. Reservoir temperature, in-situ stress difference and αθ are primary factors affecting hydraulic fracturing, whereas h is a secondary factor. When the reservoir temperature rises from 50°C to 150°C, the initiation and breakdown pressures decrease by 65.5% and 16.7%, respectively. HFs cross the bedding plane more easily, and fracture complexity is obviously enhanced. A higher h is favourable for slightly reducing the initiation and breakdown pressures, but it has little influence on the fracture complexity. Once the in-situ stress difference is low, there is a high fracture complexity, but HFs are more easily captured by bedding planes to limit the propagation of fracture height. When the in-situ stress difference is high, HFs are more likely to form bi-wing fractures. Whether αθ is too large or small, it is not conducive to improving the fracture complexity. In this study, when αθ is 30°, HFs and bedding planes intersect to form a fracture network. Essentially, thermal shock plays a key role in reducing the initiation pressure and forming multiple HFs during the fracturing process, and fracture propagation mainly depends on the injection pressure. The results can serve as reasonable suggestions for the optimization of shale hydraulic fracturing.

Experimental study on uniaxial compression mechanical properties of recycled concrete with silica fume considering the effect of curing age

• Stress-strain curve characteristics of RAC at different curing ages. • Two damage modes of mesoscopic fracture and yield were considered. • The peak nominal stress state and the critical state were distinguished. • The mesoscopic damage evolution mechanism of RAC under loading was analyzed. • The critical state was recommended as the limit state of the constitutive model. Using recycled coarse aggregate (RCA) instead of natural coarse aggregate (NCA) to produce recycled coarse aggregate concrete (RAC) can alleviate the environmental problems caused by the demolition of buildings and reduce the dependence on natural resources. In order to improve the inherent defects such as low compressive strength and elastic modulus of RAC, silica fume (SF) was used to replace part of cement to prepare RAC. Uniaxial compression test was carried out to explore the effects of curing age and SF on the properties of RAC. The microstructure of the specimen was characterized by nuclear magnetic resonance (NMR), acoustic emission (AE), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Statistical damage theory was used to explore the mesoscopic damage evolution mechanism of RAC. The results showed: with the growth of age, the hydration reaction was further sufficient, and the peak stress and elastic modulus were increased; The addition of SF improved the microstructure and mechanical properties of RAC. Considering the existence of two mesoscopic damage modes of fracture and yield, the deformation failure mechanism of RAC was analyzed from the perspective of effective stress. The relationship between the macroscopic mechanical properties of RAC and the mesoscopic damage mechanism was established by analyzing the evolution law for 5 characteristic parameters.

Mesoscopic damage mechanism and a constitutive model of shale using in-situ X-ray CT device

With the continuous development of shale gas engineering in China, an accurate and adequate understanding of shale damage mechanism has become a critical scientific problem addressed by rock mechanics. So far, many researchers have studied the fracturing process and mechanism of shale in multi-scales. The mesoscopic structural characteristics of shale during loading can be obtained using the in-situ X-ray computed tomography (CT) technology. Some scholars have observed the structure evolution of shale under in-situ uniaxial compression conditions, but the quantitative investigation of damage evolution and constitutive model of shale still requires further studies. Given this, the in-situ micro-CT device was adopted to study the macroscopic mechanical response and the mesoscopic structural evolution of Longmaxi shale under uniaxial compression conditions. The evolution law of the damage variable with the axial strain was analysed according to the characterisation of the damage variable based on the CT image grey variance. In combination with the macroscopic stress-strain curve shape, evolution stage of the mesoscopic void, evolution of the damage variable, mesoscopic mechanism of the macroscopic mechanical response was investigated, and a damage constitutive model of shale under the uniaxial compression test was proposed. The conclusion of this study can provide a foundation for further research into the multi-scale failure mechanism of shale and exert theoretical guidance significance on shale gas fracturing engineering practice.

Stress–Strain Behavior of FRC in Uniaxial Tension Based on Mesoscopic Damage Model

Fiber-reinforced concrete (FRC) is widely used in the field of civil engineering. However, the research on the damage mechanism of FRC under uniaxial tension is still insufficient, and most of the constitutive relations are macroscopic phenomenological. The aim is to provide a new method for the investigation of mesoscopic damage mechanism of FRC under uniaxial tension. Based on statistical damage theory, the damage constitutive model for FRC under uniaxial tension is established. Two kinds of mesoscopic damage mechanisms, fracture and yield, are considered, which ultimately determines the macroscopic nonlinear stress–strain behavior of concrete. The yield damage mode reflects the potential bearing capacity of materials and plays a key role in the whole process. Evolutionary factor is introduced to reflect the degree of optimization and adjustment of the stressed skeleton in microstructure. The whole deformation-to-failure is divided into uniform damage phase and local failure phase. It is assumed that the two kinds of damage evolution follow the independent triangular probability distributions, which could be represented by four characteristic parameters. The validity of the proposed model is verified by two sets of test data of steel fiber-reinforced concrete. Through the analysis of the variation law of the above parameters, the influence of fiber content on the initiation and propagation of micro-cracks and the damage evolution of concrete could be evaluated. The relations among physical mechanism, mesoscopic damage mechanism, and macroscopic nonlinear mechanical behavior of FRC are discussed.

Numerical simulation of hydraulic fracturing of hot dry rock under thermal stress

The hot dry rock (HDR) hydraulic fracturing is a complex physical process coupling the effects of seepage, stress, temperature, and damage. The high temperature and brittleness of the HDR leads to the great thermal stress, and the rock is possibly thermally damaged, thus promoting hydraulic fracture (HF) extension and significantly improving the permeability around the HF. In this paper, a thermo-hydro-mechanical-damage (THMD) coupling model is established based on elastic thermodynamics, Biot's classic seepage mechanics and mesoscopic damage mechanics, and its accuracy is evaluated through case study and verification with theoretical models and experiments. The evolution of multi-physics during hydraulic fracturing of HDR is studied, and the effects of rock thermophysical parameters, temperature difference, rock heterogeneity, Young's modulus, permeability, and injection rate on HF extension in the HDR are investigated. The results show that initially, due to the severe temperature variation near the borehole, the higher thermal expansion coefficient leads to the greater thermal tensile stress and facilitates rock damage, thus reducing the fracture pressure. The research results provide theoretical basis and technical support for fracturing design of geothermal system.

Simulation of Crack Initiation and Propagation in the Crystals of a Beam Blank

Surface cracking seriously affects the quality of beam blanks in continuous casting. To study the mechanism of surface crack initiation and propagation under beam blank mesoscopic condition, this study established a polycrystalline model using MATLAB. Based on mesoscopic damage mechanics, a full implicit stress iterative algorithm was used to simulate the crack propagation and the stress and strain of pores and inclusions of the polycrystalline model using ABAQUS software. The results show that the stress at the crystal boundary is much higher than that in the crystal, cracks occur earlier in the former than in the latter, and cracks extend along the direction perpendicular to the force. When a polycrystalline model with pores is subjected to tensile stress, a stress concentration occurs when the end of the pores is perpendicular to the stress direction, and the propagation and aggregation direction of the pores is basically perpendicular to the direction of the tensile stress. When a polycrystalline model with impurities is subjected to force, the stress concentrates around the impurity but the strain here is minimal, which leads to the crack propagating along the impurity direction. This study can provide theoretical guidance for controlling the generation of macroscopic cracks in beam blanks.

Dynamic mechanical properties of artificial jointed rock samples subjected to cyclic triaxial loading

The mechanical behavior of artificial jointed rock samples with different joint dip angles was analysed on the basis of the results of cyclic triaxial tests with 1.0Hz frequency under different stress amplitudes and different confining pressures. It was found that the dynamic strength decreases with increasing joint dip angles and increases with increasing confining pressures. The stress ratio (the ratio of the maximum stress of the cyclic loading to the static triaxial compressive strength) can comprehensively reflect the influences of joint dip angles, confining pressures and stress amplitudes. For all samples with different joint dip angles, confining pressures and stress amplitudes, the number of cycles at failure decreases with increasing stress ratios. And the evolutionary characteristics of the residual axial strain and residual dilatancy with loading cycles, as well as the evolution law of damages, are determined by the stress ratios. As the stress ratio changes, the evolution laws of the residual strain and the damages form three kinds of situations. A damage variable is defined using the sum of absolute values of the volumetric contraction and dilatancy, which can consider the initial fatigue damage of jointed rocks under cyclic loading and reflect laws of the dynamic damage evolution. During each loading cycle, the samples are slightly compacted and then dilate largely in the reloading stage, while dilate slightly and are largely compacted when unloading. The volumetric strain exhibits a series of significant changing rule within a cycle and with the increasing number of cycles, which contributes to reveal the mesoscopic damage mechanism in the cyclic loading condition. Finally, the confining pressure and the joint dip angle strongly influence the dynamic deformation and failure mechanism of jointed rock samples by affecting the generating of the weak zone along the joint plane and the initiation and propagation of micro-cracks.