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

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 of Influence of Mudstone Interlayer on Compressive Strength of Salt Rock

2012 ◽  
Vol 512-515 ◽  
pp. 1953-1956
Author(s):  
Feng Shan Han ◽  
Song Li
Keyword(s):  
Numerical Simulation ◽  
Compressive Strength ◽  
Natural Gas ◽  
Radioactive Waste ◽  
Mechanical Behavior ◽  
Uniaxial Compressive Strength ◽  
Failure Process ◽  
Physical Experiment ◽  
Salt Rock ◽  
Oil And Natural Gas

Salt rock is think of ideal storage location for oil and natural gas and radioactive waste deposited, interlayer has negative effect on stability of cavern of storage for oil and natural gas and radioactive waste deposited in salt rock, It is difficult to make complete specimen layered salt rock with interlayer. In this paper Based on Rock Failure Process Analysis Code RAFP2D, influence of mudstone interlayer on uniaxial compressive strength of salt rock is investigated by numerical simulation. Numerical simulation shown that when mechanical parameters such as elastic modulus poison’s ratio and uniaxial compressive strength for salt rock and pure mudstone interlayer and content of mudstone interlayer in salt rock are known, compressive strength and mechanical behavior for salt rock with mudstone interlayer can be effectively and accurately analyzed using RFAP2D. The results for numerical simulation are agreement with true physical experiment of salt rock with mudstone interlayer. It should be noticed that the true physical experimental uniaxial compressive strength of rock is in range of 30% mean uniaxial compressive strength of rock element in RFPA2D，in this case the results for numerical simulation can reflect phenomenon and behavior for true physical experiment of salt rock with mudstone interlayer. That provides new method and avenue to analyze and investigate mechanical behavior for multilayer rock mass based on RAFP2D

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.

Study of the Effect of Joint Trace Lengths on Failure Strength of Rock

2014 ◽  
Vol 501-504 ◽  
pp. 603-606
Author(s):  
Yun Jie Zhang ◽  
Tao Xu
Keyword(s):  
Compressive Strength ◽  
Process Analysis ◽  
Failure Process ◽  
Strain Curve ◽  
Peak Stress ◽  
Experimental Results ◽  
Peak Strain ◽  
Joint Orientation ◽  
Trace Length ◽  
Failure Patterns

Numerical simulations the different rock sample in the uniaxial compression have been conducted using Rock Failure Process Analysis program (RFPA2D) to evaluate the effects of joint trace lengths on the overall mechanical behaviour of jointed rock masses in this paper. Numerically simulated stress-strain curve, peak stress, peak strain and failure patterns were compared with the corresponding experimental results. We found that for a series of partially-spanning joint geometries with the same joint orientation, the projected area will be proportional to the square of the trace length. Thus, the relationship between compressive strength and partially-spanning joint geometry for the tests carried out to explore the influence of joint trace length may be expressed as a linear correlation between compressive strength and projected area.Numerical simulations agree well with experimental results.

Numerical Study of Elastic-Brittle Failure of Notched Openings in Rocks

2005 ◽  
Vol 297-300 ◽  
pp. 2605-2611
Author(s):  
Shan Yong Wang ◽  
S.K. Au ◽  
K.C. Lam ◽  
Chun An Tang
Keyword(s):  
Numerical Study ◽  
Progressive Failure ◽  
Process Analysis ◽  
Failure Process ◽  
Confining Pressure ◽  
Numerical Code ◽  
Tunnel Wall ◽  
Model Studies ◽  
Borehole Breakout ◽  
Rock Failure Process

Borehole breakout is the process by which portions of borehole or tunnel wall fracture or spall when subjected to compressive stresses. The stress-strain characteristics of rock during loading and unloading confining pressure are studied firstly. To overcome the difficulties in analytical model studies, a numerical code, RFPA2D (Rock Failure Process Analysis), developed by CRISR, Northeastern University, China, is used to investigate the progressive failure of breakout around tunnel. The heterogeneity of rock was also taken into account in the software. The numerical simulation reproduces the formation notch in rocks by the growth, interaction and coalescence of randomly distributed macrocracks. It is illustrated from the numerical simulated results that breakout direction of tunnel is parallel with the minor stress tensor in the plane perpendicular to the borehole axis. Specifically due to the inclusion of heterogeneity, some peculiarities are studied both in the evolution of fracture and the influence of borehole on the peak intensity of specimen as well as the AE event patterns.

Producing Mechanism and Distribution Laws of Remote Cracks for Geotechnical Engineering Structure

2011 ◽  
Vol 50-51 ◽  
pp. 869-874
Author(s):  
Hou Quan Zhang ◽  
Xing Gen Huang ◽  
Li Bing Xue ◽  
Yan Feng Zhang
Keyword(s):  
Shear Crack ◽  
Process Analysis ◽  
Geotechnical Engineering ◽  
Failure Process ◽  
Pressure Coefficient ◽  
Confining Pressure ◽  
Necessary Condition ◽  
Engineering Structure ◽  
Rock Failure Process ◽  
Distribution Laws

The purpose of this paper is to investigate producing mechanism and distribution laws of remote cracks for geotechnical engineering structure. The fracture modes of geotechnical material containing a hole with different lateral confining pressure coefficients of 0, 0.05, 0.1, 0.15, 0.25, 0.33, 0.75 and 1 were numerically simulated using RFPA2D (rock failure process analysis) code. The results indicate that under a certain confining pressure, three types of cracks, i.e., primary crack, remote crack and shear crack, can be observed simultaneously in the same sample. When the lateral pressure coefficient is satisfied that 0<k<0.33, the remote cracks in en echelon forms occur in the remote region from the hole. The minimum distance of remote crack from the hole boundary is more than 0.5r (“r” denotes the radius of hole). Remote cracks are resulted by the connection of many micro vertical tensile cracks. The distribution laws of remote cracks are followed by the modulus r (i=1, 2, 3, 4). A primary tensile crack is one necessary condition for the occurrence of remote cracks for circular geotechnical engineering structure.

Numerical Study on the Fracture Evolution around Cavities in Rock

2005 ◽  
Vol 297-300 ◽  
pp. 2598-2604
Author(s):  
Shan Yong Wang ◽  
S.K. Au ◽  
K.C. Lam ◽  
Chun An Tang
Keyword(s):  
Shear Fracture ◽  
Model Simulation ◽  
Numerical Study ◽  
Process Analysis ◽  
Failure Process ◽  
Confining Pressure ◽  
Numerical Code ◽  
Tensile Fracture ◽  
Fracture Evolution ◽  
Rock Failure Process

By using numerical code RFPA2D (Rock Failure Process Analysis), the evolution of fracture around cavities subjected to uniaxial and polyaxial compression is examined through a series of model simulation. It is shown from the numerical results that the chain of events leading to the collapse of the cavity may involve all or some of the fractures designated as primary tensile, shear and remote fracture. Numerical simulated results reproduce the evolution of three types of fractures. Under the condition of no confining pressure, the tensile mode dominates with collapse coinciding with the sudden and explosive appearance of the secondary tensile fracture; at moderate higher confining pressure, the tensile mode is depressed, comparatively, the shear effect is strengthened. Nevertheless, tensile fractures especially in remote fractures stage still play a role; at higher pressure, the shear fracture dominates the remote fractures. In addition, the evolution and interact of fractures between multiple cavities is investigated, considering the stress redistribution and transference in compressive and tensile stress field.

scholarly journals Numerical simulation study on rheological failure characteristics of rock mass under high stress

2020 ◽  
Vol 192 ◽  
pp. 04003
Author(s):  
Liming Qiu ◽  
Xueqiu He ◽  
Dazhao Song ◽  
Zhenlei Li
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Failure Process ◽  
High Stress ◽  
Sudden Change ◽  
Confining Pressure ◽  
Simulation Software ◽  
The Body ◽  
Failure Characteristics ◽  
Rock Failure Process

This paper uses the RFPA numerical simulation software to establish a numerical model of the rheological failure of the rock mass under stress. Rheological failure characteristics of the body was researched, and the results shows: (1) The rupture sequence of rock rupture is from the corner to the middle. When the rock loses stability under pressure, the rock often ruptures from the corner. The corner gradually collapses and cracks. Then the cracks spread to the middle of the rock. Many cracks extending from the corners are in the rock. The central part intersects each other and eventually causes the rock to break. (2) Rock samples of different lithologies have different stress values when they break under the same confining pressure. From the experimental process, we know that granite>sandstone>mudstone. Therefore, the higher the strength of the rock, the harder the rock will be broken. (3) The weaker the plasticity at rupture, the stronger the brittleness and the stronger the sudden change of rupture. In the deep mining process, the greater the confining pressure, the more obvious the rheological characteristics of the rock, and the greater the total energy released during the rock failure process.

Strength and Deformation Characteristics of Stabilized Silty Soil

2012 ◽  
Vol 594-597 ◽  
pp. 512-515
Author(s):  
Zheng Rong Zhao ◽  
Hong Xia Yang
Keyword(s):  
Internal Friction ◽  
Brittle Failure ◽  
Yellow River ◽  
Strain Curve ◽  
Friction Angle ◽  
Confining Pressure ◽  
Alluvial Plain ◽  
The Yellow River ◽  
Stress Strain Curve ◽  
Silty Soil

Combined with the silty soil characteristics of the Yellow River alluvial plain and the subgrade filling of Ji-He expressway, the paper discusses silty soil, stabilized silty soil strength and stress-stain characteristics through the indoor triaxial shear test. The results show that the remodeling silty soil has obvious peak, brittle failure, low residual strength after being destroyed and the stress-strain curve shows a softening type in confining pressure 100kPa lower stress level. In the confining pressure 400kPa higher stress level, soil samples peak is not obvious,mainly plastic failure and the stress-strain curve is close to a hardening type. Compared to mixed with 8% lime, stabilized silty soil of mixed with 4% cement and 4% lime shows that the partial stress peak is more obvious when destroyed and the residual strength is drastically reduced and more incline to brittle failure. In different the age, compared to mixed with 8% lime, stabilized silty soil of mixed with 4% cement and 4% lime shows that internal friction angle becomes larger and cohesion improves gradually whose amplitude is much larger than internal friction angle. Therefore, a more effective way to stabilize the silty soil of the Yellow River alluvial plain is to select silty soil mixed with 4% cement and 4% lime.

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.

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