Numerical Studies on the Failure Process of Heterogeneous Rock Material with Preexisting Fracture under Uniaxial Compression

Zhang, Qi; Ma, Dawei; Liu, Jiangfeng; Zhang, Kai; Fan, Zhiqiang

doi:10.1155/2018/9203549

Cited by 10 publications

(7 citation statements)

References 42 publications

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“…In statistical modeling, the Weibull distribution function is considered a suitable function to reflect the mesoheterogeneity of rock and is usually used to describe heterogeneous rock. In previous studies, some simulation methods can already simulate the rock heterogeneity, such as the RFPA, DEM, and DDA method [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Based on the assumption that the rock mesoelement parameters meet the Weibull distribution, Tang et al [6,7] introduced the heterogeneity model in the RFPA method, which was proven to be feasible.…”

Section: Introductionmentioning

confidence: 99%

DDA Simulation Study on Mechanical Failure of Heterogenous Rock

Ning

Yang

2021

Geofluids

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Heterogeneity is an important characteristic that affects the mechanical behavior of rock. In the present work, a statistical rock mesoheterogeneity model based on the Weibull distribution function is introduced into the discontinuous deformation analysis (DDA) method to simulate the mechanical failure of heterogeneous rock, in which the general heterogeneity degree is controlled by a heterogeneity index and the mechanical property of each subblock element is randomly assigned. Brazilian disc and uniaxial compressive rectangular specimens are simulated as examples. Results show that it is more reasonable to consider the heterogeneity of elasticity properties (the elastic modulus and Poisson’s ratio) and strength properties (the tensile strength, cohesion, and friction angle) simultaneously in the heterogeneity model. It is also shown that with a larger heterogeneity index, which means a lower degree of heterogeneity, the reproducibility of the macroscopic response curves of a specimen gets better, while the exact cracking always differs but with less scattered cracks, and the global fracturing failure pattern and mode are weakly influenced by the heterogeneity. Moreover, with the increase in the heterogeneity index, the macroscopic equivalent modulus and strength get larger and approach those of a homogeneous specimen. This work indicates the importance of heterogeneity for rock mechanical behaviors including the macroscopic equivalent response and the fracturing failure. By the subblock DDA method to simulate fracturing realistically, the fracturing failure process of heterogeneous rock can be successfully reproduced, which builds good foundation for the simulation study of heterogeneous rock fracturing in practical problems, e.g., coal and rock fracturing in fluidization mining in the future.

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Section: Introductionmentioning

confidence: 99%

DDA Simulation Study on Mechanical Failure of Heterogenous Rock

Ning

Yang

2021

Geofluids

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“…e evolution process is the precursor and prerequisite for the localization and instability of the rock mass, and it plays a decisive role in the ultimate failure mode of the rock mass [2][3][4]. Specifically, these initial defects are considered to be especially important structures that control the strength of a rock.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of the Dynamic Tensile Mechanical Properties of a Coal Sandstone Disc with a Central Hole

2020

Advances in Civil Engineering

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Deep mine rocks are often subjected to rock burst induced by dynamic load. The existence of initial holes will reduce the mechanical properties of rocks and affect the stability and safety of the tunnel excavating. In order to study the effect of the ratios of inner and outer diameter on disc specimen dynamic mechanical properties and failure modes, we use cylindrical sandstone specimens of Φ50 × 25 mm to process center holes of different diameters, and a series of dynamic splitting test were carried out with a system of split Hopkinson pressure bar (SHPB) with the diameter of Φ50 mm when the pressure is 0.15 MPa, 0.3 MPa, and 0.5 MPa. The results show that (1) the dynamic tensile stress-time-history curve exhibited double peak phenomena, and the second peak value is less than the first peak value, (2) the dynamic tensile stress peaks decrease nonlinearly with the increasing of the ratios of inner and outer diameter, and the dependence is more obvious when the pressure is higher, and (3) there is a tensile crack running along the loading direction in the failure modes of the five samples with the ratio of inner to outer diameter under three kinds of impact pressure. Under the same impact pressure, when the ratio of inner diameter to outer diameter is greater than the critical ratio of inner diameter to outer diameter, there is an obvious empty hole effect; that is, the sample develops secondary tensile cracks that develop from the upper and lower ends of the pore disc to the center of the inner hole. With the increase of the ratio of inner diameter to outer diameter, the width of the penetration crack increases. With the increase of impact pressure, the critical ratio of inner diameter to outer diameter decreases gradually. The research results have certain significance for understanding the mechanical properties of porous rocks.

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“…In addition, shale reservoirs always contain kinds of joints caused by the geological deposition and folding [25][26][27]. The existing joints have a significant influence on the initiation and propagation of the induced hydraulic fractures [28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulations of Fracture Propagation in Jointed Shale Reservoirs under CO₂ Fracturing

Zhang

Liu

et al. 2019

Geofluids

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Water-based hydraulic fracturing for the exploitation of shale gas reservoirs may be limited by two main factors: (1) water pollution and chemical pollution after the injection process and (2) permeability decrease due to clay mineral swelling upon contact with the injection water. Besides, shale rock nearly always contains fractures and fissures due to geological processes such as deposition and folding. Based on the above, a damage-based coupled model of rock deformation and gas flow is used to simulate the fracturing process in jointed shale wells with CO 2 fracturing. We validate our model by comparing the simulation results with theoretical solutions. The research results show that the continuous main fractures are formed along the direction of the maximum principal stress, whilst hydraulic fractures tend to propagate along the preexisting joints due to the lower strength of the joints. The main failure type is tensile damage destruction among these specimens. The preexisting joints can aggravate the damage of the numerical specimens; the seepage areas of the layered jointed sample, vertical jointed sample, and orthogonal jointed sample are increased by 32.5%, 29.16%, and 35.05%, respectively, at time t = 39 s compared with the intact sample. The preexisting horizontal joints or vertical joints promote the propagation of hydraulic fractures in the horizontal direction or vertical direction but restrain the expansion of hydraulic fractures in the vertical or horizontal direction.

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Numerical Studies on the Failure Process of Heterogeneous Rock Material with Preexisting Fracture under Uniaxial Compression

Cited by 10 publications

References 42 publications

DDA Simulation Study on Mechanical Failure of Heterogenous Rock

DDA Simulation Study on Mechanical Failure of Heterogenous Rock

Experimental Study of the Dynamic Tensile Mechanical Properties of a Coal Sandstone Disc with a Central Hole

Numerical Simulations of Fracture Propagation in Jointed Shale Reservoirs under CO₂ Fracturing

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Numerical Studies on the Failure Process of Heterogeneous Rock Material with Preexisting Fracture under Uniaxial Compression

Cited by 10 publications

References 42 publications

DDA Simulation Study on Mechanical Failure of Heterogenous Rock

DDA Simulation Study on Mechanical Failure of Heterogenous Rock

Experimental Study of the Dynamic Tensile Mechanical Properties of a Coal Sandstone Disc with a Central Hole

Numerical Simulations of Fracture Propagation in Jointed Shale Reservoirs under CO2 Fracturing

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Numerical Simulations of Fracture Propagation in Jointed Shale Reservoirs under CO₂ Fracturing