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Creep damage constitutive model of rock based on the mechanisms of crack-initiated damage and extended damage

Underground Space 2024年第5期18卷 295-313页

作者： Tianbin Li Chao Chen Feng Peng Chunchi Ma Mou Li Yixiang Wang State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu 610059China College of Environment and Civil Engineering Chengdu University of TechnologyChengdu 610059China School of Urban Construction Chengdu PolytechnicChengdu 610218China Shudao Investment Group Co. LtdChengdu 610094China

Since the classical element model cannot describe the nonlinear characteristics of rock during the entire compressive creep process,nonlinear elements and creep damage are generally introduced in the model to resolve this ***,several previous studies have reckoned that creep damage in rock only occurs in the accelerated creep stage and is only described by the Weibull ***,the creep damage mechanism of rocks is still not clearly *** this study,a reasonable representation of the damage variables of solid materials is ***,based on the Gurson damage model,the damage state functions reflecting the constant creep stage and accelerated creep stage of rock are ***,the one-dimensional and three-dimensional creep damage constitutive equations of rock are derived by modifying the Nishihara ***,the creep-acoustic emission tests of phyllite under different confining pressures are conducted to examine the creep damage characteristics of *** the proposed constitutive model is verified by analyzing the results of creep tests performed on saturated ***,this study reveals the relationship between the creep characteristics of rocks and the corresponding damage evolution pattern,which bridges the gap between the traditional theory and the quantitative analysis of rock creep and its damage pattern.

关键词： Rock Creep damage Constitutive model Damage state function Indoor tests

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Characterization of geological uncertainties from limited boreholes using copula-based coupled Markov chains for underground construction

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Underground Space 2024年第3期16卷 94-105页

作者： Fan Wang Heng Li Gang Li Zheng-Jun You Elton J.Chen National Center of Technology Innovation for Digital Construction Huazhong University of Science and TechnologyWuhan 430074China Department of Civil and Hydraulic Engineering Huazhong University of Science and TechnologyWuhan 430074China Department of Building and Real Estate The Hong Kong Polytechnic UniversityKowloon 999077Hong KongChina Shanghai Tunnel Engineering Co. Ltd.Shanghai 200032China Wuhan Metro Group Co.Ltd. Wuhan 430070China

This paper proposes an efficient method for quantifying the stratigraphic uncertainties and modeling the geological formations based on *** Markov chains are used to describe the soil transitions along different directions,and the transition probability matrices(TPMs)of the Markov chains are analytically expressed by *** copula expression is efficient since it can represent a large TPM by a few unknown *** to the analytical expression of the TPMs,the likelihood function of the Markov chain model is given in an explicit *** estimation of the TPMs is then re-casted as a multi-objective constrained optimization problem that aims to maximize the likelihoods of two independent Markov chains subject to a set of parameter *** the method which determines the TPMs by counting the number of transitions between soil types,the proposed method is more statistically ***,a random path sampling method is presented to avoid the directional effect problem in *** soil type at a location is inferred from its nearest known neighbors along the cardinal directions.A general form of the conditional probability,based on Pickard’s theorem and Bayes rule,is presented for the soil type *** proposed stratigraphic characterization and simulation method is applied to real borehole data collected from a construction site in Wuhan,*** is illustrated that the proposed method is accurate in prediction and does not show an inclination during simulation.

关键词： Geological stratigraphy Markov chain Transition probability matrix Statistical method Copula

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Study on the structure of offshore wind and solar hybrid power generation device under the background of green energy

Study on the structure of offshore wind and solar hybrid pow...

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2023 International Conference on Mechatronics and Smart Systems, CONF-MSS 2023

作者： Wang, Hansheng Yang, Yanbin Zhang, Shujun Department of Construction Management Xi'an University of Architecture and Technology Xi'an China Department of Civil Engineering Tianjin University Tianjin China Department of Civil Engineering Chang'an University Xi'an China

There are sufficient solar and wind energy in the sea, which can be used as a good power generation energy and obtain great energy value. Therefore, the development of offshore green energy has become the mainstream trend. This paper mainly focuses on the study of offshore wind solar energy generation structures. This paper first introduces the principle of wind power generation and photovoltaic power generation and the existence of a large amount of energy offshore, and then leads to the basic structure of wind-solar hybrid power generation structure. Then it further studies the power generation, wind load, wave load, initial stability and economic type. Finally, the advantages and future environmental benefits of the structure are summarized, and the structure is reformed reasonably. The results show that the structure has good stability, load bearing capacity and economy, and the construction difficulty of the improved structure has been reduced. © 2023 Institute of Physics Publishing. All rights reserved.

关键词： Solar energy

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Performance evaluation and factors influencing a drinking water treatment plant, Shire Indassilassie, Ethiopia

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Water-Energy Nexus 2024年第1期7卷 235-242页

作者： Mesfun, Nguse Mekonen Derib, Sisay Demeku College of Engineering Department of Civil Engineering Addis Ababa Science and Technology University Addis Ababa EthiopiaP.O. Box: 16417 Ethiopia Construction Quality and Technology Center of Excellence Addis Ababa Science and Technology University Addis Ababa EthiopiaP.O. Box: 16417 Ethiopia Faculty of Water Technology Department of Water Supply and Environmental Engineering Aksum University Shire Indassilassie Tigray Ethiopia P.O. Box: 314 Ethiopia

This research assesses the efficacy of the water treatment plant in Shire Indassilassie, Tigray, Ethiopia, focusing on the slow sand filtration system. Despite the inclusion of horizontal roughing filtration and a sedimentation tank, the water treatment plant struggles with an inadequate and turbid water supply. This study evaluates the water treatment plant's performance through field evaluation, interviews, and laboratory experiments, concentrating on major treatment processes to identify performance-limiting factors. The water source had an average turbidity of 29.70 ± 1.03 NTU in the dry season and 94.27 ± 16.71 NTU in the summer. Results indicate that horizontal roughing filtration, sedimentation tank, and slow sand filtration achieve average turbidity removal efficiencies of 42.02% ± 4.00%, 5.67% ± 3.15%, and 83.51% ± 8.75%, respectively, during the dry season. In the summer or wet season, these treatment units achieve efficiencies of 40.06% ± 3.26%, 28.17% ± 4.62%, and 77.07% ± 4.61%, respectively. Additionally, the average run times for slow sand filtration are 22 days in the dry season and 13 days in the summer. Total and fecal coliform removals were effective, except in the sedimentation tank. A one-way ANOVA confirms a significant difference in turbidity among treatment units. Factors such as fine filter sand particles causing faster clogging, pipe misconnections, inadequate cleaning practices, irregular filtration rates, air binding due to a lack of backfilling at startup, and a lack of periodic monitoring and emergency response lead to suboptimal turbidity removal and shorter slow sand filtration run times. The study underscores the need for corrective measures to address these issues, enhancing water treatment plant sustainability in the region. © 2024

关键词： Water filtration

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Structural Damage Identification Using Ensemble Deep Convolutional Neural Network Models

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Computer Modeling in engineering & Sciences 2023年第2期134卷 835-855页

作者： Mohammad Sadegh Barkhordari Danial Jahed Armaghani Panagiotis G.Asteris Department of Civil and Environmental Engineering Amirkabir University of TechnologyTehranIran Department of Urban Planning Engineering Networks and SystemsInstitute of Architecture and ConstructionSouth Ural State UniversityChelyabinskRussian Department of Computational Mechanics Laboratory School of Pedagogical and Technological EducationAthensGreece

The existing strategy for evaluating the damage condition of structures mostly focuses on feedback supplied by traditional visualmethods,which may result in an unreliable damage characterization due to inspector subjectivity or insufficient level of *** a result,a robust,reliable,and repeatable method of damage identification is *** learning algorithms for identifying structural damage are evaluated in this article,which use deep convolutional neural networks,including simple averaging,integrated stacking,separate stacking,and hybridweighted averaging ensemble and differential evolution(WAE-DE)*** identification is carried out on three types of *** proposed algorithms are used to analyze the damage of 4585 structural *** effectiveness of the ensemble learning techniques is evaluated using the confusion *** the testing dataset,the confusion matrix achieved an accuracy of 94 percent and a minimum recall of 92 percent for the best model(WAE-DE)in distinguishing damage types as flexural,shear,combined,or undamaged.

关键词： Machine learning ensemble learning algorithms convolutional neural network damage assessment structural damage

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Theory and Numerical Analysis of b Non-Equivalent Cast-in-Siteb Prefabricated Concrete Shear Wall 7

Theory and Numerical Analysis of b Non-Equivalent Cast-in-Si...

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7th International Conference on civil Architecture and Structural engineering, ICCASE 2023

作者： Zhang, Zhongwei Bai, Guoliang Luo, Fajiang Lu, Huayong Xu, Guangxing Ren, Leping School of Civil Engineering Xi'an University of Architecture and Technology China China Construction Third Engineering Bureau Group Northwest Co. Ltd China

ISBN: (纸本)9781643684123

'Equivalent cast-in-site' is the current consensus on the seismic performance of fabricated buildings from home and overseas, that is, through reliable construction and connection measures, the macroscopic seismic performance of fabricated buildings is not lower than that of cast-in-place reinforced concrete structure. However, the research shows that the failure mechanism, damage forms and seismic performance indexes of prefabricated structures are different from those of cast-in-site structures, and the theory of 'non-equivalent cast-in-site' is more consistent with the characteristics of stress, force transmission and connection deterioration of prefabricated structures. In this paper, a macroscopic 'non-equivalent' numerical calculation method is proposed for the fabricated shear wall connected by grouting sleeve. First, a numerical calculation model of shear wall without considering the influence of sleeve connection and one that can consider the influence of sleeve connection are established, respectively, and the difference in carrying capacity between the two models is compared and analyzed. Furthermore, the strain values of concrete, reinforcement and joints in the calculation model of 'non-equivalent' shear wall under nonlinear push over analysis are obtained, and the material properties and failure mechanism are analyzed. It is hoped that the research results can be valuable for the calculation and analysis of assembled walls. © 2023 The Authors.

关键词： Shear walls

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IMPACT OF GROUNDED LOW CALCIUM FLY ASH ON THE STRENGTH OF GEOPOLYMER CONCRETE

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Indian Concrete Journal 2025年第2期99卷 34-39页

作者： Ojha, Avinash Agrawal, Unnati S. Daiya, Rahul Jain, Aman Ahlawat, Aman Aggarwal, Praveen Department of Civil Engineering Sir Padampat Singhania University Udaipur India School of Construction NICMAR University Pune India Sir Padampat Singhania University Udaipur India Jaipur India University of Science and Technology Haryana India Kurukshetra India

This research investigates the influence of the fineness of low-calcium fly ash on the compressive strength of geopolymer concrete. Fly ash was procured from two different thermal power plants and subjected to grinding in a Los Angeles Abrasion Testing Machine for 250 and 500 revolutions to achieve finer particle sizes. Geopolymer concrete was synthesized by activating these fly ashes with a 14M sodium hydroxide (NaOH) and sodium silicate (Na₂SiO₃) solution mixed in the ratio of 1:2.5, respectively, to produce the alkaline activator solution. The activated fly ash was then combined with fine and coarse aggregates and water to form the concrete mix. Specimens were heat-cured at 80°C for 24 hours to enhance geopolymerization. Compressive strength tests revealed that increased fly ash fineness led to a significant enhancement in strength, with improvements of approximately 7 % for chabra low calcium fly ash (CLCF)-based concrete and 9 % for kota low caclium fly ash (KLCF)-based concrete. These findings highlight the importance of fly ash fineness in enhancing geopolymer concrete’s mechanical properties, confirming its potential for sustainable construction Future research could explore the impact of varied curing conditions, different fly ash sources, and long-term durability tests to further enhance the understanding and applicability of geopolymer concrete. © 2025, Associated Cement Companies Ltd.. All rights reserved.

关键词： Fly ash

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Deformation Properties of Used Mortar and Recycled Brick Aggregate

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Journal of Wuhan University of technology(Materials Science) 2025年第2期40卷 462-475页

作者： WANG Lei LIANG Zhuoran YONG Yi CAO Feng TANG Wenlong HUANG Zhuqin Guangxi Key Laboratory of Green Building Materials and Construction Industrialization Guilin 541004China School of Civil Engineering Guilin University of TechnologyGuilin 541004China CCCC First Highway Xiamen Engineering Co.Ltd. Xiamen 361021China CCCC-SHEC Seventh Highway Engineering Co.Ltd. Nanning 530220China Guangxi Mesda Engineering Machinery Co.Ltd. Nanning 530201China

In order to study the effects of the contents of used mortar recycled aggregate(OMRA)and brick recycled aggregate(BRA)on the deformation properties of recycled aggregate concrete(RAC),under uniaxial compression conditions,The RAC of OMRA(0%,5%,10%,and 15%)and BRA(0%,3%,6%,9%,12%,and 15%)were *** experimental results show that,under uniaxial compression,the interfacial relationships of RAC containing OMRA and BRA between different materials are more complex,and the failure mechanism is also more *** content of OMRA and BRA had significant influence on the deformation behavior of *** the content of OMRA and BRA is high,it is difficult for existing formulas and models to accurately represent the actual *** this study,the influence of OMRA and BRA content is taken into account,and the existing formulas for calculating concrete deformation are modified,so that these formulas can more accurately calculate the elastic modulus,peak strain and ultimate strain of recycled *** stress-strain formula of Guo concrete fits the stress-strain curve of concrete very *** modified the formula on the basis of Guo formula to make the formula more suitable for the stress-strain curve of recycled concrete containing old mortar and brick,and the theoretical model proposed has better fitting *** study provides a valuable reference for nonlinear analysis of recycled aggregate concrete structures under different proportions of OMRA and BRA.

关键词： recycled aggregate concrete old mortar brick elastic modulus peak strain stress-strain curve

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Energy characteristics of saturated Jurassic sandstone in western China under different stress paths

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Deep Underground Science and engineering 2025年第1期4卷 158-168页

作者： Yi Yang Jian Lin Yun Wu Shilong Peng Wanhang Shao Lining Yang Anhui Provincial Key Laboratory of Building Structure and Underground Engineering Anhui Jianzhu UniversityHefeiChina College of Civil Engineering Anhui Jianzhu UniversityHefeiChina State Key Laboratory of Intelligent Construction and Healthy Operation&Maintenance of Deep Underground Engineering China University of Mining and TechnologyXuzhouChina Department of Earth and Environmental Sciences The University of ManchesterManchesterUK

To study the energy evolution and failure characteristics of saturated sandstone under unloading conditions,rock unloading tests under different stress paths were *** energy evolution mechanism of the unloading failure of saturated sandstone was systematically explored from the perspectives of the stress path,the initial confining pressure,and the energy conversion *** results show that(1)before the peak stress,the elastic energy increases with an increase in deviatoric stress,while the dissipated energy slowly increases *** the peak stress,the elastic energy decreases with the decrease of deviatoric stress,and the dissipated energy suddenly *** energy release intensity during rock failure is positively correlated with the axial stress.(2)When the initial confining pressure is below a certain threshold,the stress path is the main factor influencing the total energy *** the axial stress remains constant and the confining pressure is unloading,the total energy is more sensitive to changes in the confining *** the axial stress remains constant,the compressive deformation ability of the rock cannot be significantly improved by the increase in the initial confining *** initial confining pressure is positively correlated with the rock's energy storage limit.(3)The initial confining pressure increases the energy conversion rate of the rock;the initial confining pressure is positively correlated with the energy conversion rate;and the energy conversion rate has a high confining pressure *** increase in the axial stress has a much greater impact on the elastic energy than the confining pressure.(4)When the deviatoric stress is small,the confining pressure mainly plays a protective *** with the case of triaxial compression paths,the rock damage is more severe under unloading paths,and compared with the case of constant axial stress,the rock damage is more severe under increasing axial stress.

关键词： energy evolution failure characteristics sandstone stress path unloading

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An end-to-end 3D seismic simulation of underground structures due to point dislocation source by using an FK-FEM hybrid approach

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Frontiers of Structural and civil engineering 2022年第12期16卷 1515-1529页

作者： Zhenning BA Jisai FU Zhihui ZHU Hao ZHONG State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China School of Civil Engineering Tianjin UniversityTianjin 300350China National Engineering Research Center of High Speed Railway Construction Technology Central South UniversityChangsha 410075China School of Civil Engineering Central South UniversityChangsha 410075China

Based on the domain reduction idea and artificial boundary substructure method,this paper proposes an FK-FEM hybrid approach by integrating the advantages of FK and FEM(i.e.,FK can efficiently generate high-frequency three translational motion,while FEM has rich elements types and constitutive models).An advantage of this approach is that it realizes the entire process simulation from point dislocation source to underground *** with the plane wave field input method,the FK-FEM hybrid approach can reflect the spatial variability of seismic motion and the influence of source and propagation *** approach can provide an effective solution for seismic analysis of underground structures under scenario of earthquake in regions where strong earthquakes may occur but are not recorded,especially when active faults,crustal,and soil parameters are *** Daikai subway station as an example,the seismic response of the underground structure is simulated after verifying the correctness of the approach and the effects of crustal velocity structure and source parameters on the seismic response of Daikai station are *** this example,the influence of velocity structure on the maximum interlayer displacement angle of underground structure is 96.5%and the change of source parameters can lead to the change of structural failure direction.

关键词： source-to-structure simulation FK-FEM hybrid approach underground structures point dislocation source

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