Dynamic behavior of rock during its post failure stage in SHPB tests

Zhou, Zilong; Zhao, Yuan; Jiang, Yihui; Yang, Zhen; Cai, Xun; Li, Diyuan

doi:10.1016/s1003-6326(17)60021-9

Cited by 55 publications

(21 citation statements)

References 21 publications

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“…Besides, the lengths of transmitted bar and incident bar were set to 0.75 m and 1.5 m. The density of bars particles and striker particles is 7810 kg/m 3 , and the contact bond strength was selected to be high enough to avoid damage during the impact test. The previous studies have been revealed that these settings are feasible [27,28]. Because the impact velocity of striker in laboratory test was 9.4∼10.2 m/s, and the impact velocity of analogue striker was set to be 10 m/s.…”

Section: Basic Methodology Of Pfcmentioning

confidence: 99%

Dynamic Fracturing Behavior of Layered Rock with Different Inclination Angles in SHPB Tests

Qiu

et al. 2017

Shock and Vibration

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The fracturing behavior of layered rocks is usually influenced by bedding planes. In this paper, five groups of bedded sandstones with different bedding inclination angles are used to carry out impact compression tests by split Hopkinson pressure bar. A highspeed camera is used to capture the fracturing process of specimens. Based on testing results, three failure patterns are identified and classified, including (A) splitting along bedding planes; (B) sliding failure along bedding planes; (C) fracturing across bedding planes. The failure pattern (C) can be further classified into three subcategories: (C1) fracturing oblique to loading direction; (C2) fracturing parallel to loading direction; (C3) mixed fracturing across bedding planes. Meanwhile, a numerical model of layered rock and SHPB system are established by particle flow code (PFC). The numerical results show that the shear stress is the main reason for inducing the damage along bedding plane at = 0 ∘ ∼75∘ . Both tensile stress and shear stress on bedding planes contribute to the splitting failure along bedding planes when the inclination angle is 90 ∘ . Besides, tensile stress is the main reason that leads to the damage in rock matrixes at = 0 ∘ ∼90∘ .

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Section: Basic Methodology Of Pfcmentioning

confidence: 99%

Dynamic Fracturing Behavior of Layered Rock with Different Inclination Angles in SHPB Tests

Qiu

et al. 2017

Shock and Vibration

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“…At present, there are few reports on studies of rock with defects under dynamic loading. Zhou [14,15] analyzed the crack propagation and failure process of prefabricated cracks and holes in layered sandstone and marble, respectively, by using a high-speed camera and described the effects of the crack inclination, hole shape, and size on the dynamic compressive strength. Li et al [16] carried out experiments on prismatic marble specimens containing a single flaw using a modified SPHB and revealed that the geometry of the flaws may have a slight effect on the failure modes of flawed rock under impact loading.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Damage Characteristics and Energy Dissipation of Rocks with a Vertical Hole under Cyclic Impact Loads

Dai

Luo

Chen³

et al. 2020

Advances in Civil Engineering

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This study systematically investigates the failure patterns, energy dissipation, and fracture behavior of rock specimens containing a vertical hole under impact loads. First, an improved damage calculation equation suitable for the analysis of rock specimens with a vertical hole is obtained based on the one-dimensional stress wave theory and the interface continuity condition. After that, the Hopkinson pressure bar (SHPB) device was used to conduct cyclic impact tests with different impact pressures and impact modes (impact pressures with equal amplitude and unequal amplitude). The experimental results suggest that, under the equal-amplitude high pressure and unequal-amplitude pressure, the degree of damage of the rock significantly increased, the bearing capacity greatly reduced, and the rock gradually transitions from having good ductility to experiencing brittle failure. The cumulative specific energy absorption value gradually increases with the increase in the cyclic impact. Compared to that of the equal impact condition, the degree of damage to the rock is more severe for the case of equal-amplitude high pressure and unequal impact, and the failure mode undergoes a transformation from transverse tensile failure to transverse tensile failure-axial splitting failure combination and axial splitting failure. Through the analysis of rock energy changes and rock failure patterns during cyclic impact, it will be helpful to predict and control the fracture caused by local stress concentration during excavation, thus can reduce the cost of support and reinforcement in excavation and improve the stability of surrounding rocks.

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“…A universal integration scheme would, however, be preferable. Finally, also material failure is considered in modern constitutive models for geotechnical materials where hardening or softening behavior can be observerd . The time scale of various creep stages and failure observed in rock salt differ by orders of magnitude, requiring additional considerations for time adaptivity.…”

Section: Introductionmentioning

confidence: 99%

Error‐controlled implicit time integration of elasto‐visco‐plastic constitutive models for rock salt

Zhang

Nagel

2020

Num Anal Meth Geomechanics

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The mechanical behavior of rock salt is rate-dependent at different time scales. Using caverns in rock salt formations for renewable energy storage implies that the underground structures are subjected to both short-term and long-term loads, increasing robustness and flexibility requirements for numerical simulators used to assess the safety of such structures. So far, explicit time integration with model-specific heuristics for time-step size determination dominate in application studies. In this paper, the suitability of error-controlled adaptive time-integration schemes of the diagonally implicit Runge-Kutta type is investigated in comparison with the Backward Euler and Crank-Nicolson schemes when applied to the integration of typical elasto-visco-plastic constitutive models of rock salt. The comparison is made both for monotonic and for cyclic loads as well as taking account of thermo-mechanical coupling. Analyses of the time-integration errors and the time step-size evolution show the suitability of the integration scheme for these material models. The automatic adjustment of the time-step size was found to be robust across all material models and boundary conditions as well as for non-isothermal situations for a single algorithmic parameter set. KEYWORDS error control, implicit Runge-Kutta, rock salt, time adaptivity, viscoplasticity INTRODUCTIONA wide range of time-integration schemes, both implicit and explicit, have been implemented into software packages for the numerical simulation quasi-static and dynamic problems in geotechnics. 1,2 Because a balance has to be sought between using shorter step sizes to increase accuracy and decreasing simulation times by using larger step sizes, 3,4 researchers have paid much attention to the numerical stability and accuracy of different integration schemes depending on the chosen step size. 5-8 The choice of a suitable time-integration scheme depends to a certain degree on the problem modelled. This article is concerned with the integration of complex inelastic constitutive models for rock salt.The mechanical behavior of rock salt is rate-dependent, causing time-dependent stress and strain fields associated with primary, secondary, or tertiary creep or stress-relaxation processes developing at different time scales. 9 These processes are furthermore dependent on the current state of the material, eg, the acting stress, the presence of damage, or the current This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Dynamic behavior of rock during its post failure stage in SHPB tests

Cited by 55 publications

References 21 publications

Dynamic Fracturing Behavior of Layered Rock with Different Inclination Angles in SHPB Tests

Dynamic Fracturing Behavior of Layered Rock with Different Inclination Angles in SHPB Tests

Analysis of the Damage Characteristics and Energy Dissipation of Rocks with a Vertical Hole under Cyclic Impact Loads

Error‐controlled implicit time integration of elasto‐visco‐plastic constitutive models for rock salt

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