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numerical analysis of anisotropic stiffness and strength for geomaterials

Journal of Rock Mechanics and Geotechnical engineering 2023年第2期15卷 323-338页

作者： Fei Song Manuel A.González-Fernández Alfonso Rodriguez-Dono Leandro R.Alejano Department of Civil and Environmental Engineering Universitat Politècnica de Catalunya(UPC)Barcelona08034Spain CINTECX GESSMin GroupDepartment of Natural Resources and Environmental EngineeringUniversity of VigoVigo36310Spain International Centre for Numerical Methods in Engineering(CIMNE) Barcelona08034Spain

In numerical modelling,selection of the constitutive model is a critical factor in predicting the actual response of a *** use of oversimplified or inadequate models may not be sufficient to reproduce the actual geomaterial *** selection is especially relevant in the case of aniso-tropic rocks,and particularly for shales and slates,whose behaviour may be affected,*** stability in geothermal or oil and gas production *** this paper,an alternative anisotropic constitutive model has been implemented in the finite element method software CODE_BRIGHT,which is able to account for the anisotropy of shales and slates in terms of both deformability and *** this purpose,a transversely isotropic version of the generalised Hooke’s law is adopted to represent the stiffness anisotropy,while a nonuniform scaling of the stress tensor is introduced in the plastic model to represent the strength ***,a detailed approach has been proposed to determine the model parameters based on the stressestrain results of laboratory ***,numerical analyses are performed to model uniaxial and triaxial tests on Vaca Muerta shale,Bossier shale and slate from the northwest of Spain(NW Spain slate).The experimental data have been recovered from the literature in the case of the shale and,in the case of the slate,performed by the authors in terms of stress-strain curves and strengths.A good agreement can be generally observed between numerical and experi-mental results,hence showing the potential applicability of the approach to actual case ***,the presented constitutive model may be a promising approach for analysing the anisotropic behaviour of rocks and its impact on well stability or other relevant geomechanical problems in aniso-tropic rocks.

关键词： Rock mechanics Anisotropy numerical modelling CODE_BRIGHT Shale Slate

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In-situ measurements of corrosion rate: methods and observed values 2nd

In-situ measurements of corrosion rate: Methods and observed...

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2nd Workshop on Capacity Assessment of Corroded Reinforced Concrete Structures, CACRCS DAYS 2020

作者： Andrade, C. CIMNE: International Center for Numerical Methods in Engineering-UPC Spain

ISBN: (纸本)9782940643103

Measurement of the corrosion on site has been approached mainly by visual inspection complemented by the determination of the chloride content or the carbonation depth in the concrete. The measurement of the loss in diameter of the bar, which is the crucial parameter for structural assessment has very seldom aroused interest, and even less the question of which are the possible variations in the same structure. in the present communication will first be commented the methods for on-site determination of the corrosion penetration and the corrosion rate as indicated in Rilem Recommendation on the Measurement of the Polarization Resistance. Typical levels of corrosion in function of the type of concrete and its level of contamination will be presented. The effect of climatic conditions will be underlined as in this is another critical aspect when site assessment is made. Details on how many samples to take and how to interpret the results will be commented together with recommendations on how to generalize measurements on a single visit. © 2021, Fédération internationale du Béton – international Federation for Structural Concrete.

关键词： Corrosion rate

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A coarse-grained bonded particle model for large-scale rock simulation

Rock Mechanics Bulletin

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Rock Mechanics Bulletin 2024年第4期3卷 58-69页

作者： Chengshun Shang Liping Li Kaiwei Chu Zongqing Zhou Guillermo Casas Wenfeng Tu Yuxue Chen Shangqu Sun School of Qilu Transportation Shandong University250061JinanChina International Center for Numerical Methods in Engineering(CIMNE) 08034BarcelonaSpain Universitat Politecnica de Catalunya(UPC) 08034BarcelonaSpain Geotechnical and Structural Engineering Research Center Shandong University250061JinanChina College of Civil Engineering and Architecture Shandong University of Science And Technology266590QingdaoChina

For solving the computationally intensive problem encountered by the discrete element method(DEM)in simulating large-scale engineering problems,it is essential to establish a numerical model that can effectively simulate large-scale *** this study,the coarse-graining effect of a linear-Mindlin with bonding model was studied in the unconfined compression strength(UCS)and Brazilian tensile strength(BTS)*** found that the main reason for the coarse-graining effect of the BTS tests is that the type I fracture toughness is positively correlated with the size of the *** on the results analysis and fracture mechanics,the coarse-grained(CG)modeling theory was combined with a bonded particle model(BPM)for the first time and a coarse-grained bonded particle model(CG-BPM)was developed,which can be effectively used to model the tensile strength of large-scale rocks with different particle *** excavation damage zone(EDZ)in an underground research laboratory(URL)was selected as an application case,which shows that the coarse-grained bonding model presented in this paper is more accurate and reliable than the traditional one in large-scale rock simulation,at least in the scenario where tensile failure is dominant.

关键词： numerical simulation Discrete element method(DEM) Coarse-grained bonded particle model(CGBPM) Large-scale rock

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Advances in the description of corrosion induced cracking (Key-note lecture) 2nd

Advances in the description of corrosion induced cracking (K...

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2nd Workshop on Capacity Assessment of Corroded Reinforced Concrete Structures, CACRCS DAYS 2020

作者： Andrade, Carmen Anaya, Pablo CIMNE: International Center for Numerical Methods in Engineering-UPC Spain UPM-Politechnical University of Madrid Spain

ISBN: (纸本)9782940643103

The steps in the corrosion development from depassivation of the reinforcement until cracking of the concrete cover, has been studied mainly through computer simulations, although also some very interesting papers have been published on the steel/concrete interface in the preliminary steps of corrosion. In the lecture, based in new tests made by the authors on bond strength of wires, it will be presented some advances on the description of the corrosion processes progressively developed after corrosion initiation and which are the most accessible influencing factors. The parameters that whose calibration is described are: a) the oxide expansion, b) the rust bulk modulus, c) the "porous zone" thickness, d) the generated empty space of the incipient cracks in the diffusion of the oxides. © 2021, Fédération internationale du Béton – international Federation for Structural Concrete.

关键词： Steel corrosion

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Documenting rock mass failure with UAV during an emergency phase: Castell de Mur case study 13

Documenting rock mass failure with UAV during an emergency p...

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13th Landslides and Engineered Slopes. Experience, Theory and Practice, ISL

作者： Roger, Ruiz-Carulla Corominas, Jordi CIMNE International Centre for Numerical Methods in Engineering Spain UPC Universitat Politècnica de Catalunya-BarcelonaTech Spain

The understanding of the conditioning factors and of the mechanisms involved in rockfalls are requirements for a successful risk assessment and for the prevention of future events. In that respect, the detailed documentation of past event may contribute to this goal. This communication presents methodologies based on UAV surveys to collect detailed documentation of a rock failure as fast as possible to allow the opening of the affected road. The Castell de Mur rock mass failure was a catastrophic mass movement involving around 18.000 m3 and causing 2 fatalities. We use this case to show the possibilities of immediate UAV surveys to create products and models to characterize and document a rock mass failure. The photogrammetric products (orthophoto, Digital Elevation Model, 3D Point cloud and 3D texturized mesh) are used to characterize the rock failure obtaining: high-resolution topographic maps;the block size distribution of fragments in the deposit;the total mobilized volume estimated;the distribution of rock bridges from scar image analysis;and finally, the identification of the involved joint sets and interpretation of the failure mechanism. These products may be used to characterize the failure and to identify the key features for subsequent stability analysis. The realization of the UAV flight has allowed us to collect detailed information about the failure scar and the rockfall debris that would otherwise have been lost after the clean-up of the site and implementation of the remedial works. © 2021 Landslides and Engineered Slopes. Experience, Theory and Practice

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Statistical considerations of corrosion initiation and propagation 2nd

Statistical considerations of corrosion initiation and propa...

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2nd Workshop on Capacity Assessment of Corroded Reinforced Concrete Structures, CACRCS DAYS 2020

作者： Andrade, Carmen Izquierdo, David CIMNE: International Center for Numerical Methods in Engineering Madrid Spain UPM: Politechnical University of Madrid Spain

ISBN: (纸本)9782940643103

Active corrosion initiates when the pH on the rebar surface decreases. This decrease is produced either by the arrival of the carbonation front or by the local depassivation due to the chloride attack. The progression of this corrosion would depend on several variables which are function of the variability of the material itself, of its aging with time and of the external climatic conditions. All of them produce an "intrinsic" variability which is necessary to be characterized for the accuracy of the predictions of service life. In the present communication, the statistical analysis made for the characterization of chloride threshold is discussed, as well as the spatial and temporal variability of the corrosion arte in real exposure conditions. © 2021, Fédération internationale du Béton – international Federation for Structural Concrete.

关键词： Corrosion

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A coarse-grained bonded particle model for large-scale rock simulation

岩石力学通报（英文）

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岩石力学通报（英文） 2024年第4期3卷 58-69页

作者： Chengshun Shang Liping Li Kaiwei Chu Zongqing Zhou Guillermo Casas Wenfeng Tu Yuxue Chen Shangqu Sun School of Qilu Transportation Shandong University250061JinanChina International Center for Numerical Methods in Engineering(CIMNE) 08034BarcelonaSpain Universitat Politecnica de Catalunya(UPC) 08034BarcelonaSpain School of Qilu Transportation Shandong University250061JinanChina Geotechnical and Structural Engineering Research Center Shandong University250061JinanChina School of Qilu Transportation Shandong University250061JinanChina International Center for Numerical Methods in Engineering(CIMNE) 08034BarcelonaSpain College of Civil Engineering and Architecture Shandong University of Science And Technology266590QingdaoChina

For solving the computationally intensive problem encountered by the discrete element method(DEM)in simulating large-scale engineering problems,it is essential to establish a numerical model that can effectively simulate large-scale *** this study,the coarse-graining effect of a linear-Mindlin with bonding model was studied in the unconfined compression strength(UCS)and Brazilian tensile strength(BTS)*** found that the main reason for the coarse-graining effect of the BTS tests is that the type I fracture toughness is positively correlated with the size of the *** on the results analysis and fracture mechanics,the coarse-grained(CG)modeling theory was combined with a bonded particle model(BPM)for the first time and a coarse-grained bonded particle model(CG-BPM)was developed,which can be effectively used to model the tensile strength of large-scale rocks with different particle *** excavation damage zone(EDZ)in an underground research laboratory(URL)was selected as an application case,which shows that the coarse-grained bonding model pre-sented in this paper is more accurate and reliable than the traditional one in large-scale rock simulation,at least in the scenario where tensile failure is dominant.

关键词： numerical simulation Discrete element method(DEM) Coarse-grained bonded particle model(CG-BPM) Large-scale rock

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A deterministic pathogen transmission model based on high-fidelity physics

arXiv

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arXiv 2022年

作者： Löhner, Rainald Antil, Harbir Gimenez, Juan Marcelo Idelsohn, Sergio Oñate, Eugenio Center for Computational Fluid Dynamics College of Science George Mason University FairfaxVA22030-4444 United States Department of Mathematical Sciences George Mason University FairfaxVA22030 United States CIMNE International Center for Numerical Methods in Engineering Barcelona Spain ICREA Catalan Institution for Research and Advanced Studies

A deterministic pathogen transmission model based on high-fidelity physics has been developed. The model combines computational fluid dynamics and computational crowd dynamics in order to be able to provide accurate tracing of viral matter that is exhaled, transmitted and inhaled via aerosols. The examples shown indicate that even with modest computing resources, the propagation and transmission of viral matter can be simulated for relatively large areas with thousands of square meters, hundreds of pedestrians and several minutes of physical time. The results obtained and insights gained from these simulations can be used to inform global pandemic propagation models, increasing substantially their accuracy. Copyright © 2022, The Authors. All rights reserved.

关键词： Finite element method

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Free surface flow through rigid porous media - An overview and comparison of formulations

arXiv

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arXiv 2021年

作者： Düsterhöft-Wriggers, Wibke Larese, A. Oñate, E. Rung, T. Hamburg University of Technology Hamburg Germany Università degli Studi di Padova Padova Italy International Center for Numerical Methods in Engineering CIMNE Universitat Politécnica de Catalunya Barcelona Spain

In many applications free surface flow through rigid porous media has to be modeled. Examples refer to coastal engineering applications as well as geotechnical or biomedical applications. Albeit the frequent applications, slight inconsistencies in the formulation of the governing equations can be found in the literature. The main goal of this paper is to identify these differences and provide a quantitative assessment of different approaches. Following a review of the different formulations, simulation results obtained from three alternative formulations are compared with experimental and numerical data. Results obtained by 2D and 3D test cases indicate that the predictive differences returned by the different formulations remain small for most applications, in particular for small porous Reynolds number ReP Copyright © 2021, The Authors. All rights reserved.

关键词： Porous materials

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Towards real time assessment of earthfill dams via model order reduction

arXiv

引用

arXiv 2021年

作者： Nasika, Christina Díez, Pedro Gerard, Pierre Massart, Thierry J. Zlotnik, Sergio Avenue F.D. Roosevelt 50 BrusselsB-1050 Belgium LaCàN Universitat Politècnica de Catalunya Campus Nord UPC BarcelonaE-08034 Spain International Centre for Numerical Methods in Engineering CIMNE Barcelona Spain

The use of Internet of Things (IoT) technologies is becoming a preferred solution for the assessment of tailings dams’ safety. Real-time sensor monitoring proves to be a key tool for reducing the risk related to these ever-evolving earth-fill structures, that exhibit a high rate of sudden and hazardous failures. In order to optimally exploit real-time embankment monitoring, one major hindrance has to be overcome: the creation of a supporting numerical model for stability analysis, with rapid-enough response to perform data assimilation in real time. A model should be built, such that its response can be obtained faster than the physical evolution of the analyzed phenomenon. In this work, Reduced Order Modelling (ROM) is used to boost computational efficiency in solving the coupled hydro-mechanical system of equations governing the problem. The Reduced Basis method is applied to the coupled hydro-mechanical equations that govern the groundwater flow, that are made non-linear as a result of considering an unsaturated soil. The resulting model’s performance is assessed by solving a 2D and a 3D problem relevant to tailings dams’ safety. The ROM technique achieves a speedup of 3 to 15 times with respect to the full-order model (FOM) while maintaining high levels of accuracy. Keywords: Model Order Reduction, Reduced Basis Method, Hydro-mechanical, Coupled problem, Non-linear problems, Tailings dam © 2021, CC BY-NC-ND.

关键词： Internet of things

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