Growth Pattern Study of Closed Surface Flaw under Compression

2007 ◽  
Vol 353-358 ◽  
pp. 158-161
Author(s):  
Y.S.H. Guo ◽  
Wei Shen Zhu ◽  
Shu Cai Li ◽  
R.H.C. Wong ◽  
B. Sin
Keyword(s):  
Rock Mass ◽  
Three Dimensional ◽  
Closed Surface ◽  
Growth Patterns ◽  
Surface Flaw ◽  
Mode Iii ◽  
Surface Flaws ◽  
Crack Zone ◽  
Polyester Film ◽  
Brittle Fracture Mechanics

Under extra compressive stress, some phenomena of rock spallings and fractures often exist on rock mass located in sidewalls of underground house and tunnels. It is the reason that the crack growth and coalescence initiation from original flaws (or faults) in rock mass. In the previous studies, many researchers took a flaw as a through flaw (2-dimentional model), but the flaws are not always through the whole rock mass in fact, most of them are only near the surface of rock mass, These are so named as surface flaws. They belong to three dimensional (2-D) flaws. Now, the reports on initiation and growth of 3-D surface flaw are few. So, for the investigation on growth patterns of 3-D surface flaw, a series of samples containing a surface flaw were carried out using frozen casting resin material at about -30°C temperatures. The surface flaw was made of a polyester film was used to model a single closed flaw on rock mass. The experimental results show that the wrapping wing crack (Mode I) initiated at the ends (or tips) of surface flaw first, and then formed a kinking zone (mixed crack zone) at a certain place at the middle of surface flaw region. Some petal cracks (Mode III) and shell-shaped cracks (Mode III) would grow at the middle place of flaw. A big fin crack (Mixed Mode) also emerged in middle of flaw and grown along loading direction. Finally, a team of large cracking curved faces deformed inside the resin specimen; the whole specimen would be splitted off by the initiation and growth of the cracks. The reasons lead to the fracture patterns of 3-D closed surface flaw were provided with brittle fracture mechanics theory in the article, preliminarily.

Impact of deposition borehole geometry on mechanical spalling in nuclear waste repositories

2020 ◽  
Author(s):  
Maria Cristina Saceanu ◽  
Adriana Paluszny ◽  
Robert Zimmerman ◽  
Diego Mas Ivars
Keyword(s):  
Rock Mass ◽  
Elevated Temperatures ◽  
Domain Boundary ◽  
Three Dimensional ◽  
Growth Patterns ◽  
Spent Fuel ◽  
Stress Concentrations ◽  
Pillar Stability ◽  
Growth Step ◽  
Fracture Growth

<p>Predictions of rock spalling around deep-drilled boreholes and tunnels in underground geologic repositories in crystalline rocks remain a significant challenge, due to the heterogeneities present in the rock mass, uncertain stress fields, and the complex thermo-mechanical behaviour of the rock mass at elevated temperatures.</p><p>This study presents a three-dimensional numerical analysis of multiple fracture growth leading to spalling around a deposition borehole. The mechanical spalling due to stress amplification after drilling is simulated using a finite element-based discrete fracture growth simulator. Fractures are grown by computing stress intensity factors at each fracture tip, and the mesh is adapted to accommodate the changing fracture geometries at every growth step. The model is validated using the Äspö Pillar Stability Experiment (APSE), calibrated to simulate the drilling of a borehole in the Forsmark granite, and subjected to a far-field anisotropic triaxial stress, corresponding to the <em>in situ</em> stress model from Forsmark. The deposition tunnel is implicitly simulated by attaching the deposition borehole to a free domain boundary.</p><p>The effect of borehole geometry on the predicted spalling around a typical deposition borehole is studied. The cylindrical borehole is modified at the top to provide an access ramp for the spent fuel canisters, which can effectively improve the repository design by reducing the height of the deposition tunnel. Three cases are investigated, in which the borehole top is cylindrical, conical, and wedge-shaped, respectively. Numerical results show that spalling occurs in all cases, but the borehole geometry affects fracture nucleation and growth patterns. The enlargement of the borehole top induces higher stress concentrations at the borehole-tunnel junction, increasing the severity of spalling at the top of the borehole. The final spalled zone and the fractures-borehole interaction are illustrated for each stress and geometry scenario.</p>

scholarly journals Detecting the Mechanism behind the Transition from Fixed Two-Dimensional Patterned Sika Deer (Cervus nippon) Dermal Papilla Cells to Three-Dimensional Pattern

2021 ◽  
Vol 22 (9) ◽  
pp. 4715
Author(s):  
Guanning Wei ◽  
Hongmei Sun ◽  
Haijun Wei ◽  
Tao Qin ◽  
Yifeng Yang ◽  
...  
Keyword(s):  
Culture Condition ◽  
Sika Deer ◽  
Three Dimensional ◽  
Cervus Nippon ◽  
Dermal Papilla ◽  
Growth Patterns ◽  
The Self ◽  
Dermal Papilla Cells ◽  
Aggregative Behavior ◽  
Cell Pattern

The hair follicle dermal papilla is critical for hair generation and de novo regeneration. When cultured in vitro, dermal papilla cells from different species demonstrate two distinguishable growth patterns under the conventional culture condition: a self-aggregative three dimensional spheroidal (3D) cell pattern and a two dimensional (2D) monolayer cell pattern, correlating with different hair inducing properties. Whether the loss of self-aggregative behavior relates to species-specific differences or the improper culture condition remains unclear. Can the fixed 2D patterned dermal papilla cells recover the self-aggregative behavior and 3D pattern also remains undetected. Here, we successfully constructed the two growth patterns using sika deer (Cervus nippon) dermal papilla cells and proved it was the culture condition that determined the dermal papilla growth pattern. The two growth patterns could transit mutually as the culture condition was exchanged. The fixed 2D patterned sika deer dermal papilla cells could recover the self-aggregative behavior and transit back to 3D pattern, accompanied by the restoration of hair inducing capability when the culture condition was changed. In addition, the global gene expressions during the transition from 2D pattern to 3D pattern were compared to detect the potential regulating genes and pathways involved in the recovery of 3D pattern and hair inducing capability.

Three-dimensional stromatolites from Maastrichtian–Danian Yacoraite Formation, Argentina: modelling and assessing hydrodynamic controls on growth patterns

2021 ◽  
pp. 1-17
Author(s):  
Patricio Guillermo Villafañe ◽  
Carlos Cónsole-Gonella ◽  
Paolo Citton ◽  
Ignacio Díaz-Martínez ◽  
Silvina de Valais
Keyword(s):  
Environmental Factors ◽  
Methodological Approach ◽  
Three Dimensional ◽  
Growth Patterns ◽  
External Morphology ◽  
Water Dynamics ◽  
Microbial Composition ◽  
Depositional Processes ◽  
Run Off ◽  
Internal Arrangement

Abstract Stromatolites are biogenic sedimentary structures formed by the interplay of biological (microbial composition) and environmental factors (local hydrodynamic conditions, clastic input and/or water chemistry). Well-preserved, three-dimensional (3D) fossil stromatolites are key to assessing the environmental factors controlling their growth and resulting morphology in space and time. Here, we report the detailed analysis of well-exposed, highly informative stromatolite build-ups from a single stratigraphic horizon within the Maastrichtian–Danian Yacoraite Formation (Argentina). This study focuses on the analysis of depositional processes driving intertidal to shallow subtidal stromatolites. Overall depositional architecture, external morphology and internal arrangement (mega, macro, meso and microstructures) of stromatolite build-ups were analysed and combined with 3D photogrammetric models, allowing us to decipher the links between stromatolite structure and tidal dynamics. Results suggest that external morphology and architecture of elongated and parallel clusters grew under the influence of run-off channels. The internal morphology exhibits columnar structures where the space between columns is interpreted as recharge or discharge channels. This work supports the theory that stromatolites can be used as a high-resolution tool in the assessment of water dynamics, and provides a new methodological approach and data for the dynamic reconstruction of intertidal stromatolite systems through the geological record.

scholarly journals Joint Investigation and 3D Visual Evaluation of Rock Mass Quality

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Haiping Yuan ◽  
Chenghao Chen ◽  
Yixian Wang ◽  
Hanbing Bian ◽  
Yan Liu
Keyword(s):  
Rock Mass ◽  
Quality Evaluation ◽  
Evaluation Method ◽  
Three Dimensional ◽  
Rock Mass Classification ◽  
National Standard ◽  
Ratio Method ◽  
Rock Mass Quality ◽  
Close Range ◽  
Mass Classification

In order to realize the high efficiency quality classification and three-dimensional visualization of engineering rock mass and to solve the technical difficulties of the traditional rock mass quality evaluation method such as high labor intensity, long process time consumption, many intervention processes such as scale measurement and manual calculation, and nonintuitive classification results, this paper puts forward a 3D visual rock mass quality evaluation method and system based on close-range photography, which optimizes the traditional rock mass quality evaluation method, makes the rock mass classification three-dimensional and visible, and realizes the estimation of unrevealed rock mass quality evaluation index. The research results show the following: (1) The method of storing joint information by close-range photography and extracting joint information by human-computer interaction improves the working efficiency and the process is safe and controllable compared with the traditional method of collecting fracture parameters. (2) Based on the statistical analysis of 97 groups of roadway survey data, the comprehensive statistical regression formula between BQ value of Chinese national standard and RMR value is given, and there is a good correlation between BQ value and RMR value of rock mass quality index. (3) Based on the power-inverse ratio method, the three-dimensional model of rock mass classification of the mine was established, and the cutting model obtained the current distribution diagram of rock mass quality grade, providing scientific reference for drilling, blasting, support, and other production design optimizations.

Stochastic Three-Dimensional Joint Geometry Model and the Properties of REV for a Jointed Rock Mass

2014 ◽  
Vol 1079-1080 ◽  
pp. 266-271
Author(s):  
Wen Hui Tan ◽  
Zhong Hua Sun ◽  
Ning Li ◽  
Xiao Hong Jiang
Keyword(s):  
Rock Mass ◽  
Probability Distributions ◽  
Three Dimensional ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Open Pit ◽  
Mechanical Parameters ◽  
Geometry Model ◽  
Joint Geometry ◽  
3D Network

The lithology of rock mass isnon-homogeneity，anisotropy, andexists size effect. The mechanical parameters of rock mass gotten by engineeringapproaches cannot reflect these properties. Therefore, a newmethod of determining the mechanical parameters of jointed rock mass isproposed: gneiss in Shuichang open-pit mine was selected as a case, thefracture system of the rock mass was measured and analyzed by non-contactmeasuring system of 3GSM and probabilisticmethod,the probability distributions of geometry parameters were analyzed and a 3Djoint geometry model was made by using the program of 3D network modeling.Cubes with different sizes were selected to be tested by tri-axial compressionof numerical simulation with 3DEC based on the 3D network model of joints,thus, the REV and its mechanical parameters were determined, which providedcredible parameters for slope stability analysis.

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