Numerical Investigation for Fracture Saturation in Multilayer Sedimentary Rock in Unsymmetrical Case

2013 ◽  
Vol 690-693 ◽  
pp. 3050-3053
Author(s):  
Feng Shan Han ◽  
Li Song
Keyword(s):  
Numerical Simulation ◽  
Layer Thickness ◽  
Sedimentary Rock ◽  
Process Analysis ◽  
Failure Process ◽  
Bottom Layer ◽  
Thickness Ratio ◽  
Fracture Spacing ◽  
Layer Thickness Ratio ◽  
Rock Failure Process

Opening mode fractures in multilayer sedimentary rock often are periodically distributed with fracture spacing scaled to the thickness of the fractured layer. In this paper, based on Rock Failure Process Analysis Code RFPA2D, a three layer model with a central layer and with the different thickness top and bottom layer, progressive formation in multilayer sedimentary rock at fracture saturation in unsymmetrical case is simulated. We investigate the change of the critical fracture spacing to layer thickness ratio as a function of the thickness of the top layer where the bottom layers is much thicker (5 times) than the fractured layer called the unsymmetrical case, in this unsymmetrical case, fracture saturation is simulated. By numerical simulation of RFPA2D, the critical spacing to layer thickness ratio decreases and tend to the same constant value as the thickness of the top layer increases. Numerical simulation shown that for the unsymmetrical case, if the adjacent layers are thicker than 1.5 times the thickness of the fractured layer, the multilayer sedimentary rock can be treated approximately as a system with infinitely thick top and bottom layers at fracture saturation.That should be useful in the design of engineering systems and in the prediction of fracture spacing in hydrocarbon reservoirs and groundwater aquifers.

Numerical Simulation of Fracture Saturation in Multilayer Materials in Symmetric Case

2011 ◽  
Vol 704-705 ◽  
pp. 641-644
Author(s):  
Feg Shan Han
Keyword(s):  
Numerical Simulation ◽  
Layer Thickness ◽  
Process Analysis ◽  
Failure Process ◽  
Bottom Layer ◽  
Symmetric Case ◽  
Thickness Ratio ◽  
Central Layer ◽  
Layer Thickness Ratio ◽  
Multilayer Materials

Using Realistic Failure Process Analysis Code RFPA2D, a three layer materials model with a central layer and with the same thickness top and bottom layer, progressive formation of fracture saturation in multilayer materials is simulated in all case by numerical simulation. Our numerical simulation recurrence the phenomenon of fracture saturation in multilayer materials. numerical simulation shown that for the symmetric case the spacing of these fractures at fracture saturation are approximately the same and lineally related to thickness of the fractured layer. We investigate that the critical fracture spacing to layer thickness ratio is function of the thickness ratio of the top and bottom layers to central layer at fracture saturation. numerical simulation shown that for the symmetric case the critical spacing of fractures to layer thickness ratio decreases rapidly and tends to a constant value.

Numerical Approach to Fracture Spacing in Two Layered Material

2005 ◽  
Vol 297-300 ◽  
pp. 750-755
Author(s):  
Xu Chang ◽  
Junjie Liu ◽  
Chun An Tang ◽  
Yong Bin Zhang ◽  
Juan Xia Zhang
Keyword(s):  
Layer Thickness ◽  
Process Analysis ◽  
Failure Process ◽  
Fracture Initiation ◽  
Horizontal Stress ◽  
Numerical Approach ◽  
Thickness Ratio ◽  
Fracture Spacing ◽  
Layer Thickness Ratio ◽  
Constant State

Equally spaced opening-mode fractures always evolve in top layer attached to underlying layer. With a newly developed Material Failure Process Analysis code (MFPA2D), we have firstly investigated the stress distribution between two adjacent fractures as a function of the fracture-spacing-to-layer-thickness ratio using a two-layer model with a fractured top layer. The numerical results indicate the horizontal stress perpendicular to the fractures near the top surface changes from tensile to compressive when the fracture-spacing-to-layer-thickness ratio changes from greater than to less than a critical value. Then, the process from fracture initiation to fracture saturation is numerically modeled. The modeling of fracture process shows that the fractures initiate at the top surface and propagate to the interface between the two layers in the first stage. In the following stage, new fractures can infill between the earlier formed fractures and they always initiate at the interface and propagate to the top surface. Numerical simulation clearly demonstrates that the stress state transition precludes further infilling of fractures and the fracture spacing reaches a constant state, i.e. the so-called fracture saturation.

Numerical Simulation of Compressive Experiment for Rock with a Natural Interlayer

2012 ◽  
Vol 217-219 ◽  
pp. 1389-1392
Author(s):  
Feng Shan Han ◽  
Li Song
Keyword(s):  
Numerical Simulation ◽  
Compressive Strength ◽  
Process Analysis ◽  
Failure Process ◽  
Peak Load ◽  
Strain Curve ◽  
Confining Pressure ◽  
Physical Experiment ◽  
Stress Strain Curve ◽  
Rock Failure Process

It is difficulty to make physical experiment for compressive experiment of rock with a natural interlayer I Natural interlayer affect greatly on mechanical property of rock. In this paper, Rock Failure Process Analysis Code RFPA is used to simulate influence of natural interlayer to compressive strength of rock by numerical simulation under compression. Through numerical simulation complete stress strain curve and peak load can be obtained for compressive experiment of rock with a natural interlayer. RFPA can be effectively used to investigate anisotropy of compression for rock with natural interlayer under different confining pressure. Numerical simulation show that anisotropy of compressive strength of rock with a natural interlayer varies with inclination of natural interlayer, as the confining pressure increase, the compressive strength, the plasticity and ductility increase for rock with a natural interlayer. That provides new method to analyze and investigate mechanical behavior for multilayer composite material such as rock mass with a natural interlayer，finally Index of Anisotropy for rock with a natural interlayer are put forward

Tuning Negative Capacitance in PbZr0.2Ti0.8O3/SrTiO3 Heterostructures via Layer Thickness Ratio

2021 ◽  
Vol 16 (3) ◽  
Author(s):  
Yifei Hao ◽  
Tianlin Li ◽  
Yu Yun ◽  
Xin Li ◽  
Xuegang Chen ◽  
...  
Keyword(s):  
Layer Thickness ◽  
Thickness Ratio ◽  
Negative Capacitance ◽  
Layer Thickness Ratio

Numerical Analysis of Faults on Deep-Buried Tunnel Surrounding Rock Damaged Zones

2011 ◽  
Vol 90-93 ◽  
pp. 74-78 ◽  
Author(s):  
Jun Hu ◽  
Ling Xu ◽  
Nu Wen Xu
Keyword(s):  
Numerical Analysis ◽  
Mechanical Response ◽  
Progressive Failure ◽  
Process Analysis ◽  
Failure Process ◽  
Water Inrush ◽  
Surrounding Rock ◽  
Factors Affecting ◽  
Rock Failure Process ◽  
Tunnel Instability

Fault is one of the most important factors affecting tunnel instability. As a significant and casual construction of Jinping II hydropower station, when the drain tunnel is excavated at depth of 1600 m, rockbursts and water inrush induced by several huge faults and zone of fracture have restricted the development of the whole construction. In this paper, a progressive failure progress numerical analysis code-RFPA (abbreviated from Rock Failure Process Analysis) is applied to investigate the influence of faults on tunnel instability and damaged zones. Numerical simulation is performed to analyze the stress distribution and wreck regions of the tunnel, and the results are consistent with the phenomena obtained from field observation. Moreover, the effects of fault characteristics and positions on the construction mechanical response are studied in details. Some distribution rules of surrounding rock stress of deep-buried tunnel are summarized to provide the reasonable references to TBM excavation and post-support of the drain tunnel, as well as the design and construction of similar engineering in future.

scholarly journals Numerical Simulation of Rock Failure Process with a 3D Grain-Based Rock Model

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Zengwei Zhang ◽  
Fan Chen ◽  
Chao Zhang ◽  
Chao Wang ◽  
Tuo Wang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Mechanical Characteristics ◽  
Failure Process ◽  
Wellbore Stability ◽  
Rock Excavation ◽  
Rock Failure Process ◽  
Rock Model ◽  
Walled Cylinder

A grain-based rock model was developed and applied to study mechanical characteristics and failure micromechanics in thick-walled cylinder and wellbore stability tests. The rock is represented as an assembly of tetrahedral blocks with bonded contacts. Material heterogeneity is modeled by varying the tensile strength at the block contacts. This grain-based rock model differs from previous disk/sphere particle-based rock models in its ability to represent a zero (or very low) initial porosity condition, as well as highly interlocked irregular block shapes that provide resistance to movement even after contact breakage. As a result, this model can reach higher uniaxial compressive strength to tensile strength ratios and larger friction coefficients than the disk/sphere particle-based rock model. The model captured the rock fragmentation process near the wellbore due to buckling and spalling. Thin fragments of rock similar to onion skins were produced, as observed in laboratory breakout experiments. The results suggest that this approach may be well suited to study the rock disaggregation process and other geomechanical problems in the rock excavation.

Numerical Simulation on Failure Patterns of Rock Discs and Rings Subject to Diametral Line Loads

2004 ◽  
Vol 261-263 ◽  
pp. 1517-1522 ◽  
Author(s):  
Wan Cheng Zhu ◽  
K.T. Chau ◽  
Chun An Tang
Keyword(s):  
Tensile Strength ◽  
Standardized Test ◽  
Process Analysis ◽  
Failure Process ◽  
Brazilian Test ◽  
Rock Failure ◽  
Numerical Code ◽  
Failure Patterns ◽  
Rock Failure Process ◽  
Indirect Tensile

Brazilian test is a standardized test for measuring indirect tensile strength of rock and concrete disc (or cylinder). Similar test called indirect tensile test has also been used for other geomaterials. Although splitting of the disc into two halves is the expected failure mode, other rupture modes had also been observed. More importantly, the splitting tensile strength of rock can vary significantly with the specimen geometry and loading condition. In this study, a numerical code called RFPA2D (abbreviated from Rock Failure Process Analysis) is used to simulate the failure process of disc and ring specimens subject to Brazilian test. The failure patterns and splitting tensile strengths of specimens with different size and loading-strip-width are simulated and compared with existing experimental results. In addition, two distinct failure patterns observed in ring tests have been simulated using RFPA2D and thus this verifies the applicability of RFPA2D in simulating rock failure process under static loads.

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