Fracture evolution and failure behaviour of marble specimens containing rectangular cavities under uniaxial loading

Zhou, Zilong; Tan, Lihai; Cao, Wenzhuo; Zhou, Zhiyong; Cai, Xun

doi:10.1016/j.engfracmech.2017.08.029

Cited by 83 publications

(36 citation statements)

References 36 publications

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“…Li et al investigated the failure properties of Iddefjord granite samples containing prefabricated holes under uniaxial compression tests at laboratory and numerical scales and rockburst phenomena such as rock block ejection, and slabbing failure similar to in situ measurements was observed around the prefabricated holes under high compressive stress. Zhou et al analyzed the crack evolution law and failure behavior of marble specimens containing rectangular cavities under uniaxial loading. It was found that the number of holes and layout have a significant influence on the mechanical behavior of marble specimens.…”

Section: Introductionmentioning

confidence: 99%

Analysis of fractures of a hard rock specimen via unloading of central hole with different sectional shapes

Fan

Chen

et al. 2019

Energy Science & Engineering

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Hard rock failure and rockburst hazards under high in situ stresses have been the subject of deep rock mechanics and engineering. Previous investigations employed cubic rock specimens with a central hole for simulation of rock fracturing around deep tunnels at a laboratory scale, while the failure characteristics and crack evolution behavior around different shapes of holes induced by excavation unloading response have been barely considered. A commercially combined finite‐discrete element method (combined FEM/DEM) was used to investigate the failure characteristics and crack propagation process of typical hard rock specimens (marble) via the unloading of central hole with different shapes. Rock heterogeneity was also considered in the model in combination with the engineering reality. The combined FEM/DEM approach was first validated by simulating uniaxial compression and Brazilian tests. Then, the parametrical analysis was conducted in detail on the basis of five different sectional shapes of central holes, including a circle, ellipse, U‐shape, trapezoid, and cube, and two lateral pressure coefficients. Analysis of crack propagation paths, released strain energy, displacement, and average velocity distribution of the monitoring points around the central hole suggests that the failure degree and destruction intensity are strongly related to the sectional shape and lateral pressure coefficients. Hard and brittle rock failure induced by the excavation unloading effect can be classified as stable failure (slabbing failure) and unstable failure (strain rockburst). The cubic, trapezoidal, and U‐shaped holes within the specimen are the most likely to induce unstable failure, while stable failure is the dominant failure pattern around circular and elliptical holes. The lateral pressure coefficient λ was also found to affect failure position and intensity (only for the axisymmetric section) around the central hole. The influence of rock heterogeneity on failure intensity and range around the central hole within the specimen was also discussed. This study emphasizes the importance and necessity of the excavation unloading effect when evaluating surrounding rock failure around deep tunnels.

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Section: Introductionmentioning

confidence: 99%

Analysis of fractures of a hard rock specimen via unloading of central hole with different sectional shapes

Fan

Chen

et al. 2019

Energy Science & Engineering

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“…The movements of particles are computed based on Newton's laws of motion. Here the parallel bond model (PBM) developed by Potyondy and Cundall [28] was employed for its excellent performance of reproducing the realistic mechanical behavior of rock-like materials, which has been proved by many studies [29][30][31][32][33].…”

Section: Numerical Model In Pfcmentioning

confidence: 99%

Water Infusion on the Stability of Coal Specimen under Different Static Stress Conditions

2020

Self Cite

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Underground coal mines are frequently subjected to water infusion, resulting in many mining hazards. This study investigated the effect of water infusion on the stress and energy evolution characteristics of coal specimens representing isolated pillars under different initial axial stress conditions using the discrete element method. A water infusion distribution model was developed, in which random functions were employed to describe water distribution for the purpose of realizing the dispersion of results for a better reliability. Based on the results, a stress-level classification was presented to evaluate the water effect on pillars’ instability. For the investigated coal specimens, the water weakening effect on stress and energy remains stable when the axial geo-stress on pillars is less than 65% of uniaxial compressive strength (UCS). In contrast, when the axial stress coefficient is greater than 65%, pillars become unstable eventually. A higher axial stress coefficient is more likely to introduce a lower critical instability point of the water saturation coefficient for pillars in the process of water infusion. However, the instability point remains random to some extent for specimens following the same water distribution rule under the identical test condition. Two instability types, which also happened randomly, were observed in the numerical results for damaged coal specimens under different water saturation coefficients and axial geo-stresses, namely free-falling and step-falling.

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“…Afterwards, the randomly distributed speckles with good quality on the surfaces were formed. Based on the principle that the grayscale value of pixel stays constant during the test [33,34], the movements of speckles can be tracked through the comparison of the deformed images and the reference image. e calculation procedure of displacement and strain can be operated by GOM correlate software, including the following steps ( Figure 3): (1) choose the speckle image before deformation as a reference and a deformed image as the target, and then select the same observation region in two images; (2) divide the region into many subsets with certain sizes, and determine the initial locations of the subsets;…”

Section: Experimental Apparatusmentioning

confidence: 99%

Experimental Investigation on Fracture Evolution in Sandstone Containing an Intersecting Hole under Compression Using DIC Technique

Zhao

Liang

et al. 2019

Advances in Civil Engineering

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Failure of underground structures, especially intersections, becomes more severe as the depth increases, which poses a new challenge for the safe construction and operation of deep rock engineering. To investigate the mechanical properties and fracture behavior of rock with an intersecting hole under compressive loads, a series of uniaxial compression tests was carried out on cuboid red sandstone specimens containing an intersecting hole with three types of shapes by digital image correlation (DIC) technique. The results showed that the existing hole inside specimens leads to almost a 50% reduction of mechanical parameters from that of intact ones, and this weakening effect is associated with the shapes of holes. Failure of specimens is a progressive process in which cracks, i.e., primary tensile cracks, secondary tensile cracks, and shear cracks, initiate from stress concentration zones, propagate along certain direction, and coalesce with each other into macrofractures. Both the real-time principal strain fields and horizontal displacement fields of specimens under compression could be visually displayed by DIC system, and they were in good consistency in characterizing the fracture behavior. Moreover, the propagation characteristics of primary tensile cracks were studied further by quantitatively analyzing the strain variation during the loading process, and the propagation mechanism of “open-close-reopen” of primary tensile cracks was explained in detail.

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Fracture evolution and failure behaviour of marble specimens containing rectangular cavities under uniaxial loading

Cited by 83 publications

References 36 publications

Analysis of fractures of a hard rock specimen via unloading of central hole with different sectional shapes

Analysis of fractures of a hard rock specimen via unloading of central hole with different sectional shapes

Water Infusion on the Stability of Coal Specimen under Different Static Stress Conditions

Experimental Investigation on Fracture Evolution in Sandstone Containing an Intersecting Hole under Compression Using DIC Technique

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