CASRock—a code to simulate THMC processes in fractured geological media

2021 ◽  
Author(s):  
Pengzhi Pan
Keyword(s):  
Numerical Study ◽  
Fractured Rock ◽  
Failure Process ◽  
Coupling Scheme ◽  
State Variables ◽  
Heterogeneous Rock ◽  
Rock Failure Process ◽  
Coupled Thm Processes ◽  
High Level ◽  
Cracking Process

<p>This work presents the advancement of a self-developed Cellular Automata Software for engineering Rockmass fracturing processes (CASRock, http://en.casrock.cn/) in the applications of thermo-hydro-mechanical-chemical (THMC) processes in fractured geological media. It contains a series of previous developed numerical systems, namely EPCA for simulation of heterogeneous rock failure process, VEPCA for visco elastoplastic analysis, D-EPCA for rock dynamic response simulation, THMC-EPCA for coupled THMC processes in geological media and RDCA for simulation of rock cracking process from continuity to discontinuity. In CASRock, the non-isothermal, unsaturated fluid flow, mechanical process and chemical reaction are sequentially coupled by updating all the state variables using cellular automaton technique and finite difference method on spatial and temporal scale, respectively. The Lagrangian method is used to simulate the particle transport. The control equations, coupling scheme and numerical implementation are briefly introduced. Several applications, including  in the background of high level nuclear waste disposal are provided to show the abilities of CASRock in the simulation of coupling processes between physical fields. These applications include, (1) stability analysis of engineering rockmass under mechanical loading, (2) numerical study on coupled TM processes in hard rock pillar, (3) study on coupled THM processes in engineering barrier, (4) simulation of the THMC process in fractured rock.</p>

Numerical Study on Cracking Process of Masonry Structure

2005 ◽  
Vol 9 ◽  
pp. 117-126 ◽  
Author(s):  
Shu Hong Wang ◽  
Yong Bin Zhang ◽  
Chun An Tang ◽  
Lian Chong Li
Keyword(s):  
Numerical Analysis ◽  
Damage Mechanics ◽  
Numerical Study ◽  
Process Analysis ◽  
Failure Process ◽  
Masonry Structure ◽  
Heterogeneous Structure ◽  
Two Phase ◽  
Masonry Material ◽  
Cracking Process

Masonry structure is heterogeneous and has been widely used in building and construction engineering. The study on cracking pattern of masonry structure is significant to engineering design. Many previous investigations on the failure process of masonry structure are usually based on the homogenization technique by selecting a typical unit of masonry to serve as a representative volume. This kind of numerical analysis neglects the mesoscopic heterogeneous structure, which cannot capture the full cracking process of masonry structures. The cracking process of masonry structure is dominantly affected by its heterogeneous internal structures. In this paper, a mesoscopic mechanical model of masonry material is developed to simulate the behavior of masonry structure. Considering the heterogeneity of masonry material, based on the damage mechanics and elastic-brittle theory, the new developed Material Failure Process Analysis (MFPA2D) system was put forward to simulate the cracking process of masonry structure, which was considered as a two-phase composite of block and mortar phases. The crack propagation processes simulated with this model shows good agreement with those of experimental observations. The numerical results show that numerical analysis clearly reflect the modification, transference and their interaction of the stress field and damage evolution process which are difficult to achieve by physical experiments. It provides a new method to research the forecast theory of failure and seismicity of masonry. It has been found that the fracture of masonry observed at the macroscopic level is predominantly caused by tensile damage at the mesoscopic level.

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.

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.

Migration of Solutes in Unsaturated, Fractured Rock at Yucca Mountain: Measurements, Mechanisms, and Models

1995 ◽  
Vol 412 ◽  
Author(s):  
A. V. Wolfsberg ◽  
B. A. Robinson ◽  
J. T. Fabryka-Martin
Keyword(s):  
Solute Transport ◽  
Transport Model ◽  
Alternative Hypothesis ◽  
Fractured Rock ◽  
Yucca Mountain ◽  
Nuclear Waste Repository ◽  
Transport Studies ◽  
And Performance ◽  
High Level ◽  
A Site

AbstractCharacterization and performance assessment (PA) studies for the potential high-level nuclear waste repository at Yucca Mountain require an understanding of migration mechanisms and pathways of radioactive solutes. Measurements of 36C1 in samples extracted from boreholes at the site are being used in conjunction with recent infiltration estimates to calibrate a site-scale flow and solute transport model. This exercise using the flow and solute transport model, FEHM, involves testing different model formulations and two different hypotheses to explain the occurrence of elevated 36Cl in the Calico Hills unit (CHn) which indicates younger water than in the overlying Topopah Spring unit (TSw). One hypothesis suggests fast vertical transport from the surface via fractures in the TSw to the CHn. An alternative hypothesis is that the elevated 36C1 concentrations reflect rapid horizontal flow in the CHn or at the interface between the CHn and the TSw with the source being vertical percolation under spatially isolated regions of high infiltration or at outcrops of those units. Arguments in favor of and against the hypotheses are described in conjunction with the site-scale transport studies.

scholarly journals Thermo-hydro-mechanical processes in fractured rock formations during a glacial advance

2015 ◽  
Vol 8 (7) ◽  
pp. 2167-2185 ◽  
Author(s):  
A. P. S. Selvadurai ◽  
A. P. Suvorov ◽  
P. A. Selvadurai
Keyword(s):  
Rock Mass ◽  
Fractured Rock ◽  
Fluid Pressure ◽  
Computational Modelling ◽  
Fracture Zones ◽  
Saturated Rock ◽  
Rock Formations ◽  
Geological Formation ◽  
High Level Nuclear Waste ◽  
High Level

Abstract. The paper examines the coupled thermo-hydro-mechanical (THM) processes that develop in a fractured rock region within a fluid-saturated rock mass due to loads imposed by an advancing glacier. This scenario needs to be examined in order to assess the suitability of potential sites for the location of deep geologic repositories for the storage of high-level nuclear waste. The THM processes are examined using a computational multiphysics approach that takes into account thermo-poroelasticity of the intact geological formation and the presence of a system of sessile but hydraulically interacting fractures (fracture zones). The modelling considers coupled thermo-hydro-mechanical effects in both the intact rock and the fracture zones due to contact normal stresses and fluid pressure at the base of the advancing glacier. Computational modelling provides an assessment of the role of fractures in modifying the pore pressure generation within the entire rock mass.

Numerical Study on Influence of Joint Characters on Rock Mechanical Parameters

2011 ◽  
Vol 201-203 ◽  
pp. 2909-2912
Author(s):  
Yan Feng Feng ◽  
Tian Hong Yang ◽  
Hua Wei ◽  
Hua Guo Gao ◽  
Jiu Hong Wei
Keyword(s):  
Rock Mass ◽  
Compression Strength ◽  
Numerical Study ◽  
Process Analysis ◽  
Failure Process ◽  
Deformation Modulus ◽  
Rock Joints ◽  
Structured Surfaces ◽  
Trace Length ◽  
The Impact

Rock mass is the syntheses composed of kinds of structure and structured surfaces. The joint characters is influencing and controlling the rock mass strength, deformation characteristics and rock mass engineering instability failure in a great degree. Through using the RFPA2D software, which is a kind of material failure process analysis numerical methods based on finite element stress analysis and statistical damage theory, the uniaxial compression tests on numerical model are carried, the impact of the trace length of rock joints and the fault throws on rock mechanics parameters are studied. The results showed that with the gradual increase of trace length,compression strength decreased gradually and its rate of variation getting smaller and smaller, the deformation modulus decreased but the rate of variation larger and larger; with the fault throws increasing, the compression strength first increases and then decreases, when the fault throw is equal to the trace length, the deformation modulus is the largest. When the joint trace length is less than the fault throw, the rate of the deformation modulus is greater than that of trace length, but the deformation modulus was not of regular change.

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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