scholarly journals A new SPH-based continuum framework with an embedded fracture process zone for modelling rock fracture

2019 ◽  
Vol 159 ◽  
pp. 40-57 ◽  
Author(s):  
Yingnan Wang ◽  
Ha H. Bui ◽  
Giang D. Nguyen ◽  
P.G. Ranjith
Keyword(s):  
Fracture Process ◽  
Fracture Process Zone ◽  
Process Zone ◽  
Rock Fracture

scholarly journals Influence of Water–Oil Saturation on the Fracture Process Zone: A Modified Dugdale–Barenblatt Model

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2882 ◽  
Author(s):  
Yuanxun Nie ◽  
Guangqing Zhang ◽  
Yuekun Xing ◽  
Shiyuan Li
Keyword(s):  
Hydraulic Fracturing ◽  
Capillary Pressure ◽  
Fracture Process ◽  
Fracture Process Zone ◽  
Process Zone ◽  
Rock Fracture ◽  
Peak Load ◽  
Image Correlation ◽  
Influence Of Water ◽  
Water Saturated

The wetting and nonwetting fluid saturations in porous reservoirs always change during long-term injection and production. The fracture process zone (FPZ) is a prominent feature in the rock fracture process. If the FPZ properties are influenced by pore fluids, the process of hydraulic fracturing will change greatly. The existing models do not consider the role of pore fluid when characterizing the FPZ. In this paper, a modified Dugdale–Barenblatt (D–B) model with capillary pressure is proposed. The model reflects the fact that the FPZ length decreases nonlinearly with the increase in capillary pressure, and it reveals the mechanism of capillary pressure on the equivalent fracture cohesion in the FPZ, which affects the FPZ length. Three-point bending tests were carried out on sandstone under various fluid saturations through digital image correlation (DIC), acoustic emission (AE), and scanning electron microscope (SEM). It was found that the FPZ length of the water–oil-saturated samples was 30–50% smaller than that of water-saturated/oil-saturated samples due to the capillary pressure effect, and the modified D–B model was well consistent with the experiments. The AE behaviors of different saturated samples were not the same: The cumulative AE signals changed abruptly at 90% of the peak load for the water–oil-saturated samples and at 50% of the peak load for water-saturated samples. This demonstrated that the effect of capillary pressure was more obvious than the weakening effect of microstructural damages. The significant influence of capillary pressure on FPZ requires continuous recognition in hydraulic fracturing design.

scholarly journals The crack opening displacement of rock fracture process zone

2019 ◽  
Vol 23 (3 Part A) ◽  
pp. 1479-1486
Author(s):  
Sheng Zhang ◽  
Yang Qiao ◽  
Hong-Bao Zhao
Keyword(s):  
Distribution Function ◽  
Fracture Process ◽  
Fracture Process Zone ◽  
Process Zone ◽  
Rock Fracture ◽  
Image Correlation ◽  
Crack Model ◽  
Opening Displacement ◽  
Growth Trend ◽  
Non Linear

The original displacement value of fracture process zone can be obtained by digital image correlation technology. According to the virtual crack model, the formula to obtain the opening displacement is given in the experiment. Basing on the damage Mechanics theory and the actual deformation characteristics of fracture process zone, the traditional opening displacement distribution function of fracture process zone is modified by defining the wave coefficient and the damage factor of the horizontal elastic modulus. The measured opening displacement is compared with the opening displacement of the traditional theoretical function and modified function, and the results show that the opening displacement is non-linear fluctuation characteristic distribution influenced by damage. The revise distribution function not only reflects the overall growth trend of the opening displacement, but also reflects the local fluctuation characteristics. It has an important theoretical significance for understanding the non-linear characteristics of rock fracture process.

Experimental study on development characteristics and size effect of rock fracture process zone

2021 ◽  
Vol 241 ◽  
pp. 107377
Author(s):  
Sheng Zhang ◽  
Hongyue Wang ◽  
Xiaojun Li ◽  
Xulong Zhang ◽  
Dingchao An ◽  
...  
Keyword(s):  
Experimental Study ◽  
Size Effect ◽  
Fracture Process ◽  
Fracture Process Zone ◽  
Process Zone ◽  
Rock Fracture

Analysis of Energy Balance When Using Cohesive Zone Models to Simulate Fracture Processes

2002 ◽  
Vol 124 (4) ◽  
pp. 440-450 ◽  
Author(s):  
C. Shet ◽  
N. Chandra
Keyword(s):  
Cohesive Energy ◽  
Cohesive Zone ◽  
Strain Energy ◽  
Fracture Process ◽  
Fracture Process Zone ◽  
Process Zone ◽  
Elastic Strain Energy ◽  
Inelastic Strain ◽  
External Work ◽  
Cohesive Zone Models

Cohesive Zone Models (CZMs) are being increasingly used to simulate fracture and fragmentation processes in metallic, polymeric, and ceramic materials and their composites. Instead of an infinitely sharp crack envisaged in fracture mechanics, CZM presupposes the presence of a fracture process zone where the energy is transferred from external work both in the forward and the wake regions of the propagating crack. In this paper, we examine how the external work flows as recoverable elastic strain energy, inelastic strain energy, and cohesive energy, the latter encompassing the work of fracture and other energy consuming mechanisms within the fracture process zone. It is clearly shown that the plastic energy in the material surrounding the crack is not accounted in the cohesive energy. Thus cohesive zone energy encompasses all the inelastic energy e.g., energy required for grainbridging, cavitation, internal sliding, surface energy but excludes any form of inelastic strain energy in the bounding material.

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