TOUGH-RFPA: Coupled thermal-hydraulic-mechanical Rock Failure Process Analysis with application to deep geothermal wells

Li, Tianjiao; Tang, Chun’an; Rutqvist, Jonny; Hu, Mengsu

doi:10.1016/j.ijrmms.2021.104726

Cited by 31 publications

(7 citation statements)

References 72 publications

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“…where 𝜎 𝑖𝑗 is the stress tensor, 𝜀 𝑖𝑗 is the strain tensor, 𝐹 𝑏𝑖 is the body force, 𝛼 is the thermal expansion coefficient, ∆𝑇 is the temperature difference, 𝛿 𝑖𝑗 is the Kronecker function, 𝐺 is the shear modulus, 𝜆 is the Lame constant, E is the elastic modulus, and 𝜈 is the Poisson's ratio [33,34,39]. Reproduced from [37] with permission from Elsevier.…”

Section: Deformation Compatibility Equationmentioning

confidence: 99%

Numerical Study on Thermal Damage Behavior and Heat Insulation Protection in a High-Temperature Tunnel

Kang

Tang

et al. 2021

Applied Sciences

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Deepening our understanding of temperature and stress evolution in high-temperature tunnels is indispensable for tunnel support and associated disaster prevention as the rock temperature is remarkably high in hot dry rock (HDR) utilization and similar tunnel engineering. In this paper, we established a two-dimensional thermal–mechanical coupling model through RFPA2D-thermal, by which the temperature and stress field of the surrounding rock in a high-temperature tunnel with and without thermal insulation layer (TIL) were studied, followed by the evolution of thermal cracks. The associated sensitivity analysis of the TIL and airflow factors were then carried out. We found that (1) the tunnel rock is unevenly cooled down by the cold airflow, which induces thermal stress and damages the rock element when it exceeds the tensile strength of the rock mass. Those damaged rock elements accumulate and coalesce into visible cracks in the tunnel rock as the ventilation time goes, reducing the tunnel stability. (2) TIL effectively reduces the heat exchange between the airflow and tunnel rock and weakens the cold shock by the airflow, delaying the crack initiation which provides efficient time to adopt engineering measures for tunnel supporting. (3) TIL parameters are of pivotal importance to the long-term cold shock by the airflow. Increasing the TIL thickness and reducing the TIL thermal conductivity both significantly enhance the thermal insulation effect. The results cover the gap in the study of cold shock in high-temperature tunnels, which is helpful in designs to prevent thermal damage in high-temperature tunnels.

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Section: Deformation Compatibility Equationmentioning

confidence: 99%

Numerical Study on Thermal Damage Behavior and Heat Insulation Protection in a High-Temperature Tunnel

Kang

Tang

et al. 2021

Applied Sciences

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“…The most popular technique in THM models is a continuum approach, which is based on a mathematical framework linking sets of differential equations to explain thermodynamic, solid, and fluid mechanics laws, such as finite element [19,26,31,36,39,52], or finite difference implementations [37]. Even though they are appealing for macro-scale applications, continuum modelling approaches based on the finite element method (FEM) or the finite volume method (FVM) have significant computational and continuity limitations when applied to discontinuous and highly deformable media like packed or fluidized beds and fractured granular porous materials.…”

Section: Introductionmentioning

confidence: 99%

A novel DEM-based pore-scale thermal-hydro-mechanical model for fractured non-saturated porous materials

2022

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For fracture propagation, a novel DEM-based pore-scale thermal-hydro-mechanical model of two-phase fluid flow with heat transfer in non-saturated porous materials with low porosity was developed. Numerical computations were performed for bonded granular specimens, using a DEM fully coupled with CFD (based on a fluid flow network) and heat transfer, which integrated discrete mechanics with fluid mechanics and heat transfer at the meso-scale. Both the fluid (diffusion and advection) and bonded particles (conduction) were involved in heat transfer. The numerical findings of the coupled thermal-hydraulic-mechanical (THM) model were first compared to the analytical solution of the classic 1D heat transport problem. The numerical and analytical outcomes were in perfect agreement. Advection's impacts on the cooling of a bonded particle assembly were next numerically demonstrated for low and high Peclet numbers. Finally, the THM model's utility was proved in a thermal contraction test employing a bonded particle assembly during cooling, which resulted in the creation of a macro-crack. The effects of a macro-crack on the distribution of fluid pressure, density, velocity, and temperature were studied.

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“…Therefore, a RFPA 3D program is adopted in this study to investigate the flexural behavior and to optimize the design of FGUHPCC. 26 With a numerical model test established to simulate four-point bending based on the experimental parameters, the load-deflection curves, equivalent flexural strength, and corresponding deflection capacity were obtained. The crack evolution, horizontal displacement of specimen surface, acoustic emission (AE) activities, and the principal stress were also analyzed.…”

Section: Introductionmentioning

confidence: 99%

“…According to previous researches, 21–25 numerical simulation method is proved to be useful in further explore the failure process and pattern of structures. Therefore, a RFPA 3D program is adopted in this study to investigate the flexural behavior and to optimize the design of FGUHPCC 26 . With a numerical model test established to simulate four‐point bending based on the experimental parameters, the load–deflection curves, equivalent flexural strength, and corresponding deflection capacity were obtained.…”

Section: Introductionmentioning

confidence: 99%

Optimization design of functionally graded ultra‐high performance cementitious composite on flexural behavior

Bao

Zhang

Líu

et al. 2022

Structural Concrete

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The research aims to investigate and optimize the flexural behavior of functionally graded ultra‐high performance cementitious composite (FGUHPCC), and to optimize the design of FGUHPCC by using a numerical simulation program named RFPA3D. The equivalent flexural strength and corresponding deflection capacity of double‐ and single‐layered FGUHPCC beams were analyzed by carrying out four‐point bending test. Furthermore, with the numerical model set in RFPA3D, the crack evolution and acoustic emission (AE) event of specimens at limit of proportionality (LOP) point, modulus of rupture (MOR) point, and 30% of MOR are, therefore, discussed. The results indicate that functionally graded design can help to improve the flexural capacity and fracture toughness of all specimens. In addition, the main crack of FGUHPCC looks more irregular and larger damage areas are formed. Higher principal stress and more AE events can be identified in FGUHPCC than that of single‐layer UHPCC. Based on the recorded test data, the influence of bottom layer thickness was also investigated with respect to the peak flexural load and the AE energy. The results indicate that the optimum load capacity and flexural energy can be obtained when layer thickness ratio is about 0.6.

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TOUGH-RFPA: Coupled thermal-hydraulic-mechanical Rock Failure Process Analysis with application to deep geothermal wells

Cited by 31 publications

References 72 publications

Numerical Study on Thermal Damage Behavior and Heat Insulation Protection in a High-Temperature Tunnel

Numerical Study on Thermal Damage Behavior and Heat Insulation Protection in a High-Temperature Tunnel

A novel DEM-based pore-scale thermal-hydro-mechanical model for fractured non-saturated porous materials

Optimization design of functionally graded ultra‐high performance cementitious composite on flexural behavior

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