Fatigue damage variable and evolution of rock subjected to cyclic loading

Xiao, Ji; Ding, Dexin; Jiang, Fuliang; Xu, Guan

doi:10.1016/j.ijrmms.2009.11.003

Cited by 335 publications

(117 citation statements)

References 13 publications

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“…e increase of these variables causes the second stage to be shortened, which is related to the whole fatigue process [17]. Figure 11 shows the relationship between the deformation modulus and relative cycle times.…”

Section: Fatigue Damage Evolution Characteristicsmentioning

confidence: 99%

Effects of Cyclic Loading on the Mechanical Properties of Mature Bedding Shale

Guo

Yang

Wang

et al. 2018

Advances in Civil Engineering

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We investigated the mechanical properties of mature bedding shale under cyclic loading conditions, with an application to the design of hydraulic fracturing in shale gas wells. Laboratory experiments were conducted on shale samples under two principal loading orientations. Testing results showed that accumulated fatigue damage occurs in a three-stage process. Analysis of fatigue damage at different maximum stress levels shows that fatigue life increases as a power-law function with maximum stress decreasing. And the maximum stress significantly affects the fatigue life. Further, the elastic part of shale rock deformation was recovered in the unloading process, whereas the irreversible deformation remained. e irreversible deformation, growth trend, and accumulation of the total fatigue were directly related to the fatigue damage. is process can be divided into 3 stages: an initial damage stage, a constant velocity damage stage, and an accelerated damage stage, which accounted for about one-third of the fatigue damage. Shale rock is a nonhomogeneous material, and the bedding is well developed. Its fatigue life differs greatly in two principal loading orientations, even under the same loading conditions. All of these drawn conclusions are of great importance for design of hydraulic fracturing in shale gas wells.

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Section: Fatigue Damage Evolution Characteristicsmentioning

confidence: 99%

Effects of Cyclic Loading on the Mechanical Properties of Mature Bedding Shale

Guo

Yang

Wang

et al. 2018

Advances in Civil Engineering

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“…According to the results from cyclic loading test on the shale rock, the damage variable can be calculated by using (3). Figure 11 shows the relationship between the calculated damage variables and the strain at peak stress.…”

Section: Damage Evolution Of Shale Rock Under Cyclic Loadingmentioning

confidence: 99%

“…It is clear that the mechanical properties of rock under cyclic loading differ dramatically from those under static loads [2,3]. erefore, it is necessary to understand the response of rock mass under cyclic loading condition.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Behavior of Shale Rock under Uniaxial Cyclic Loading and Unloading Condition

Zhao

Liu

et al. 2018

Advances in Civil Engineering

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In order to investigate the mechanical behavior of shale rock under cyclic loading and unloading condition, two kinds of incremental cyclic loading tests were conducted. Based on the result of the short-term uniaxial incremental cyclic loading test, the permanent residual strain, modulus, and damage evolution were analyzed firstly. Results showed that the relationship between the residual strains and the cycle number can be expressed by an exponential function. e deformation modulus E 50 and elastic modulus E S first increased and then decreased with the peak stress under the loading condition, and both of them increased approximately linearly with the peak stress under the unloading condition. On the basis of the energy dissipation, the damage variables showed an exponential increasing with the strain at peak stress. e creep behavior of the shale rock was also analyzed. Results showed that there are obvious instantaneous strain, decay creep, and steady creep under each stress level and the specimen appears the accelerated creep stage under the 4th stress of 51.16 MPa. Based on the characteristics of the Burgers creep model, a viscoelastic-plastic creep model was proposed through viscoplastic mechanics, which agrees very well with the experimental results and can better describe the creep behavior of shale rock better than the Burgers creep model. Results can provide some mechanics reference evidence for shale gas development.

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“…Given the lifespan of the rock structure, the maximum number of cycles or the maximum amplitude that could be sustained must be assessed. Models able to reproduce evolution of rock strength with cyclic loading are very limited (Li et al, 2003;Xiao et al, 2009Xiao et al, , 2010Bastian et al, 2014;Liu et al, 2014). They mostly consist in predicting strength or strain evolution of triaxial or uniaxial laboratory tests for a given material with respect to the number of cycles.…”

Section: List Of Symbols αmentioning

confidence: 99%

Validation of a New Elastoplastic Constitutive Model Dedicated to the Cyclic Behaviour of Brittle Rock Materials

et al. 2017

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Old mines or caverns may be used as reservoirs for fuel/gas storage or in the context of large scale energy storage. In the first case, oil or gas is stored on annual basis. In the second case pressure due to water or compressed air varies on a daily basis or even faster. In both cases a cyclic loading on the cavern's/mine's walls must be considered for the design. The complexity of rockwork geometries or coupling with water flow requires finite element modelling and then a suitable constitutive law for the rock behaviour modelling. This paper presents and validates the formulation of a new constitutive law able to represent the inherently cyclic behaviour of rocks at low confinement. The main features of the behaviour evidenced by experiments in the literature depict a progressive degradation and strain of the material with the number of cycles. A constitutive law based on a boundary surface concept is developed. It represents the brittle failure of the material as well as its progressive degradation. Kinematic hardening of the yield surface allows the modelling of cycles. Isotropic softening on the cohesion variable leads to the progressive degradation of the rock strength. A limit surface is introduced and has a lower opening than the bounding surface. This surface describes the peak strength of the material and allows the modelling of a brittle behaviour. In addition a fatigue limit is introduced such that no cohesion degradation occurs if the stress state lies inside this surface. The model is validated against three different rock materials and types of experi-

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Fatigue damage variable and evolution of rock subjected to cyclic loading

Cited by 335 publications

References 13 publications

Effects of Cyclic Loading on the Mechanical Properties of Mature Bedding Shale

Effects of Cyclic Loading on the Mechanical Properties of Mature Bedding Shale

Mechanical Behavior of Shale Rock under Uniaxial Cyclic Loading and Unloading Condition

Validation of a New Elastoplastic Constitutive Model Dedicated to the Cyclic Behaviour of Brittle Rock Materials

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