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Seepage flow around twin circular tunnels in anisotropic ground revealed by an analytical solution

Underground Space 2023年第3期10卷 1-14页

作者： Fengran Wei Huaning Wang Guangshang Zeng Mingjing Jiang School of Aerospace Engineering and Applied Mechanics Tongji UniversityShanghai 200092China School of Urban Construction and Safety Engineering Shanghai Institute of TechnologyShanghai 201418China State Key Laboratory of Disaster Reduction in Civil Engineering Tongji UniversityShanghai 200092China

A new analytical solution is proposed for steady seepage flow around twin circular tunnels in fully saturated anisotropic *** solution is an exact one that fully satisfies all the boundary conditions and precisely considers the different permeabilities along two direc-tions and the interactions between twin *** solution provides a fast approach for the estimation of the seepage field and a useful tool for design *** solution is successfully addressed using problem equivalence and the Schwartz alternating method com-bined with a mapping *** a coordinate transformation of the governing equation,the anisotropic problem of circular tunnels is first equivalent to that of isotropic elliptical tunnels,and the length of the ellipse along the anisotropic axis depends on the anisotropic permeability *** Schwartz alternating method is then employed to address the solution of equivalent elliptical twin tunnel prob-lems,where a mapping function,with which an elliptical tunnel in the half-plane can be mapped into an annulus in the image plane,is introduced to solve the single tunnel problems in each iterative *** iterative procedure is quite simple and efficient in its calculations and achieves good convergence,and the analytical solution agrees very well with the numerical results to reflect its high precision in the entire ***,parametric studies are performed to investigate the influences of the anisotropic permeability and tunnel spacing on the seepage *** is the first study to provide the exact analytical solution of the seepage field of twin tunnel problems in aniso-tropic ground,and the procedure can be extended to multiple tunnel problems.

关键词： Underwater tunnel Seepage field Anisotropy Schwartz alternating method Conformal mapping method

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A Deep Learning Approach to Shape Optimization Problems for Flexoelectric Materials Using the Isogeometric Finite Element Method

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Computer Modeling in engineering & Sciences 2024年第5期139卷 1935-1960页

作者： Yu Cheng Yajun Huang Shuai Li Zhongbin Zhou Xiaohui Yuan Yanming Xu College of Architecture and Civil Engineering Xinyang Normal UniversityXinyang464000China Henan Unsaturated Soil and Special Soil Engineering Technology Research Center Xinyang Normal UniversityXinyang464000China College of Intelligent Construction Wuchang University of TechnologyWuhan430223China College of Civil Engineering and Architecture Dalian UniversityDalian116622China Henan International Joint Laboratory of Structural Mechanics and Computational Simulation School of Architecture and Civil EngineeringHuanghuai UniversityZhumadian463000China

A new approach for flexoelectricmaterial shape optimization is proposed in this *** this work,a proxymodel based on artificial neural network(ANN)is used to solve the parameter optimization and shape optimization *** improve the fitting ability of the neural network,we use the idea of pre-training to determine the structure of the neural network and combine different optimizers for *** isogeometric analysis-finite element method(IGA-FEM)is used to discretize the flexural theoretical formulas and obtain samples,which helps ANN to build a proxy model from the model shape to the target *** effectiveness of the proposed method is verified through two numerical examples of parameter optimization and one numerical example of shape optimization.

关键词： Shape optimization deep learning flexoelectric structure finite element method isogeometric

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Spatio-temporal evolution of pore and fracture structures in coal induced by initial damage and creep behavior:A real-time NMR-based approach

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International Journal of Mining Science and technology 2024年第10期34卷 1409-1425页

作者： Lei Zhang Yimeng Wang Mingzhong Gao Wenhao Jia Senlin Xie Wei Hou Xiangyu Wang Hao Zhang College of Safety&Emergency Management Engineering Taiyuan University of TechnologyTaiyuan 030024China School of Energy and Mining Engineering China University of Mining and Technology-BeijingBeijing 100083China State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering Shenzhen UniversityShenzhen 518060China School of Mechanics and Civil Engineering China University of Mining and Technology-BeijingBeijing 100083China School of Applied Science Taiyuan University of Science and TechnologyTaiyuan 030024China

Understanding the impact of mining disturbances and creep deformation on the macroscopic deformation and the microscopic pore and fracture structures(MPFS)of coal is paramount for ensuring the secure extraction of coal *** study conducts cyclic loading-unloading and creep experiments on coal using a low-field nuclear magnetic resonance(NMR)experimental apparatus which is equipped with mechanical loading units,enabling real-time monitoring the *** experiments indicated that cyclic loading-unloading stress paths initiate internal damage within coal *** identical creep stress conditions,coal samples with more initial damages had more substantial instantaneous deformation and creep deformation during the creep *** undergoing nearly 35 h of staged creep,the total strains for coal samples CC01,CC02,and CC03 reach 2.160%,2.261%,and 2.282%,*** the creep stage,the peak area ratio of seepage pores and microfractures(SPM)gradually diminishes.A higher degree of initial damage leads to a more pronounced compaction trend in the SPM of coal *** the porosity evolution of SPM during the creep process,this study proposes a novel fractional derivative model for the porosity evolution of *** efficacy of the proposed model in predicting porosity evolution of SPM is substantiated through experimental ***,an analysis of the impact mechanisms on key parameters in the model was carried out.

关键词： Coal Microscopic pore and fracture structures Initial damage Creep behavior Fractional porosity model of seepage pores and microfractures Nuclear magnetic resonance

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A Novel Passive Over-Current Trip Device for Seismic Resilience

IEEE Open Access Journal of Power and Energy

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IEEE Open Access Journal of Power and Energy 2024年 11卷 254-265页

作者： Hsu, Lai-Wan Liu, Jian-Hong Chen, Kun-Long Chen, Pei-Ching Lian, Kuo Lung Chiang, Hong-En Fan, Zhi-Kai Chen, Zhao-Yin Cheng, Chung-Liang Chung, Chi-Feng Tu, Yuan-Ching Long Men Technology Company Ltd. New Taipei24242 Taiwan National Taiwan University of Science and Technology Department of Electrical Engineering Taipei106 Taiwan National Taiwan University of Science and Technology Department of Civil and Construction Engineering Taipei106 Taiwan

The seismic resilience has become a critical concern for power systems for high-impact, low-probability disasters such as severe earthquakes. In order to enhance seismic resilience for power systems, a novel protective device, the Passive Over-Current Trip (POCT), has been designed in this paper. In the design, the POCT integrates a fuse and a mechanical switch, able to trigger the breaker to interrupt the circuit to ensure effective protection. The POCT has the trip-free feature as it fulfills its protective function without the need for an electric relay requiring a continuous power supply. The proposed POCT provides an immediate and reliable solution for the protection in high and ultra-high voltage applications. To validate the effectiveness of the proposed POCT, shockproof and tripping tests were conducted. A seismic test waveform from the Fukushima earthquake that occurred on March 11, 2011 was used to test POCT. Under such a severe earthquake, no structural or mechanical damage on the associated components in the POCT was found. Also, the POCT is also in compliance with IEEE 693 standard. Finally, various tripping tests show that the POCT can operate within 18 ms when a fault occurs in a power system, which is much shorter than that of a typical high-voltage fuse. © 2023 IEEE.

关键词： Electric circuit breakers

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Effects of Environment-friendly Polymer Composite Modifiers on the Modulus and Pavement Performance of Asphalt Mixtures

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Current Materials Science 2024年第5期17卷 498-512页

作者： Wang, Yu Liu, Wenyi Chang, Xinyue Zhang, Wengang Tianjin South Railway Station Technology Business District Development Co. Ltd Tianjin300380 China Tianjin Engineering & Construction Corporation Tianjin300384 China School of Civil Engineering and Geomatics Shandong University of Technology Zibo255049 China

Background: In the current context of low-carbon environment, it is particularly important to use waste plastics to prepare modifiers that increase the modulus of the bituminous mixture. Objectives: The study aimed to find out the influence of environment-friendly polymer composite modifier (E-FPCM) on modulus and pavement performance of bituminous mixture. Method: The influence of the optimum component E-FPCM on the dynamic modulus (DM) has been explored. The E-FPCM content’s effect on the rheological properties of bitumen has been analyzed. Also, the influence of E-FPCM on pavement performance has been analyzed. Results: The degree of influence on SR of bituminous mixture has been in the order of recycled low-density polyethene (R-LDPE) > aromatic oil > lignin fiber. The optimum composition of E-FPCM has been found to be 10% aromatic oil, 4.8% C9, 62% R-LDPE, 7.0% lignin fiber, 0.2% antioxidant 1076, 2% silane coupling agent, and 14% mineral powder. By using E-FPCM with the optimum components, the SBS bituminous mixture or 90# bituminous mixture has been found to meet the standard of a high-modulus bituminous mixture (HMBM). E-FPCM has been found to reduce the phase angle (δ) of bitumen and increase the complex shear modulus (G∗) and rutting factor [G∗/sin(δ)], which may help improve the rutting resistance (RR). Conclusion: E-FPCM is beneficial for improving the RR of the bituminous mixture, and reasonable content of E-FPCM has a great role in improving the water stability (WS) and low-temperature crack resistance (LTCR) of the bituminous mixture. © 2024 Bentham Science Publishers.

关键词： Asphalt mixtures

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Comparative Study of the Rock-breaking Mechanism of a Disc Cutter and Wedge Tooth Cutter by Discrete Element Modelling

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Chinese Journal of Mechanical engineering 2023年第3期36卷 269-285页

作者： Hua Jiang Huiyan Zhao Xiaoyan Zhang Yusheng Jiang Yaofu Zheng School of Mechanics and Civil Engineering China University of Mining and TechnologyBeijing 100083China Beijing Urban Construction Group Co. Ltd.Beijing 100088China

The operation of a shield tunnel boring machine(TBM)in a high-strength hard rock stratum results in significant cutter damage,adversely affecting the thrust and torque of the cutter ***,it is very important to carry out the research on the stress characteristics and optimize the cutter parameters of cutters break high-strength hard *** this paper,the rock-breaking performance of cutters in an andesite stratum in the tunnel of Qingdao Metro Line No.8 was investigated using the discrete element method and theoretical *** rock-breaking processes of a disc cutter and wedge tooth cutter were simulated by software particle flow code PFC^(3D),and the rock-breaking degree,stress of the cutter,and rock-breaking specific energy were *** rock damage caused by the cutter in a specific section was divided into three stages:the advanced influence,crushing,and stabilizing *** rock-breaking degree and the tangential and normal forces of the wedge tooth cutter are larger than that of the disc cutter under the same *** disc cutter(wedge tooth cutter)has the highest rock-breaking efficiency at a cutter spacing of 100 mm(110 mm)and a penetration depth of 8 mm(10 mm),and the rock-breaking specific energy is 11.48 MJ/m^(3)(12.05 MJ/m^(3)).Therefore,two types of cutters with different penetration depths or cutter spacing should be *** number of teeth of wedge tooth cutters can be increased in hard strata to improve the rock-breaking efficiency of the *** research results provide a reference for shield cutterhead selection and cutter layout in similar projects.

关键词： Qingdao andesite Rock breaking with cutter Wedge tooth cutter Specific energy PFC^(3D)

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Assessment of the Influence of Tunnel Settlement on Operational Performance of Subway Vehicles

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Structural Durability & Health Monitoring 2024年第1期18卷 55-71页

作者： Gang Niu Guangwei Zhang Zhaoyang Jin Wei Zhang Xiang Liu China Communications Construction Rail Transit Subsidiary Beijing100000China China Communications Construction Strait Construction Investment Development Co. Ltd.Fuzhou350000China School of Civil Engineering Fujian University of TechnologyFuzhou350118China

In the realm of subway shield tunnel operations,the impact of tunnel settlement on the operational performance of subway vehicles is a crucial *** study introduces an advanced analytical model to investigate rail geometric deformations caused by settlement within a vehicle-track-tunnel coupled *** model integrates the geometric deformations of the track,attributed to settlement,as track irregularities.A novel“cyclic model”algorithm was employed to enhance computational efficiency without compromising on precision,a claim that was rigorously *** model’s capability extends to analyzing the time-history responses of vehicles traversing settlement-affected *** research primarily focuses on how settlement wavelength,amplitude,and vehicle speed influence operational *** findings indicate that an increase in settlement wavelength can improve vehicle performance,whereas a rise in amplitude can degrade *** study also establishes settlement thresholds,based on vehicle operation comfort and *** insights are pivotal for maintaining and enhancing the safety and efficiency of subway systems,providing a valuable framework for urban infrastructure management and long-term maintenance strategies in metropolitan transit systems.

关键词： Settlement running performance subway tunnel dynamic analysis track irregularity threshold

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Experimental and reliability assessment of fire resistance of glue laminated timber beams

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Resilient Cities and Structures 2025年第1期4卷 101-114页

作者： Navaratnam, Satheeskumar Munmulla, Thisari Rajeev, Pathmanthan Ponnampalam, Thusiyanthan Tesfamariam, Solomon Federation University Australia BallaratVIC3353 Australia School of Engineering RMIT University Melbourne3000 Australia Department of Civil & Construction Engineering School of Engineering Swinburne University of Technology Australia Ronnie & Koh Consultants Pte Ltd 573972 Singapore Department of Civil and Environmental Engineering University of Waterloo WaterlooONN2L 3G1 Canada

Glue-laminated timber (GLT) is an engineered wood product widely used in mass timber construction for its strong structural and fire-resistant properties. However, the fire performance of GLT varies significantly due to the natural and uncertain phenomena (moisture, exposure time, isotropic, homogenous properties, etc.) of fire and timber. This makes it difficult to predict the fire behaviour of the GLT structural elements. To ensure building safety, it is crucial to assess GLT's fire behaviour and post-fire structural integrity during the design stages. This study conducted the experimental tests of GLT beams (280 mm × 560 mm) without loading (1.4 m) and under a four-point bending load (5.4 m). Tests identified thermal behaviour and charring rates of GLT beam. Then, the residual stiffness of the GLT beam was calculated, and the charring rates of the beams were compared with Australian and European standards. Reliability analysis was conducted for beams for a fire exposure of 120 min, considering the charring rates observed through the analysis and simulating the fire insulations. Results show that the charring rate of GLT made with spruce pine timber varied between 0.43 and 0.81 mm/min, with a mean rate of 0.7 mm/min, aligning with both Australian and European standards. However, considering timber density and moisture content, the charring rates in Australian standards were conservative. The study also found that structural capacity significantly degrades under fire, with a 22 % reduction in flexural stiffness after 120 min of exposure. Additionally, GLT beams can safely function for 30 min under 75 % of their design moment capacity and for 60 min under 50 % capacity. © 2025 The Author(s)

关键词： Glues

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Failure Envelopes of Single-Plate Rigid Helical Anchors for Floating Offshore Wind Turbine

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China Ocean engineering 2023年第6期37卷 1000-1010页

作者： CHEN Hong-zhen WANG Le TIAN Ying-hui ZHANG Chun-hui SHEN Zhi-chao LIU Meng-meng State Key Laboratory of Hydraulic Engineering Intelligent Construction and Operation Tianjin UniversityTianjin 300072China State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China Department of Infrastructure Engineering Faculty of Engineering and Information Technology The University of MelbourneVictoria 3010Australia School of Civil Engineering Hebei University of Science and TechnologyShijiazhuang 050018China Hebei Technological Innovation Center of Disaster Prevention and Mitigation Engineering of Geotechnical and Structural System Shijiazhuang 050018China School of Marine Science and Engineering South China University of TechnologyGuangzhou 511442China Institute of Ocean Energy and Intelligent Construction Tianjin University of TechnologyTianjin 300384China

Helical anchor is a kind of novel foundation for floating offshore wind turbines,which should be subjected to combined tensile loading caused by wind,wave and ***,the research about the capacity of helical anchor was mainly examined under uniaxial loading and scarcely explored under combined *** this study,three-dimensional finite element limit analysis is adopted to assess the bearing capacities of single-plate rigid helical anchors with different ratios of helix to shaft diameter,D_(H)/D_(S) and embedment ratios L/D_(S).Result shows that the vertical,horizontal and moment bearing capacities increase with increasing D_(H)/D_(S) and L/D_(S).The normalized V-H failure envelopes expands with increasing L/D_(S),while the normalized V-M failure envelopes tend to contract with the increase of D_(H)/D_(S).With increasing D_(H)/D_(S) or decreasing L/D_(S),the normalized H-M failure envelopes expand when the horizontal and moment loading act in the same direction and contract when they act in the opposite *** effect of D_(H)/D_(S) and L/D_(S) on the shape of H-M failure envelope become insignificant when L/D_(S)≥4.A series of failure mechanisms under different loading conditions were observed and can be used to explain the ***,a series of approximate expressions were proposed to fit the uniaxial bearing capacities and the failure envelopes.

关键词： helical anchors bearing capacity failure envelope clay

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Research Progress on the Influence of Varying Fiber Contents on Mechanical Properties of Recycled Concrete

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Structural Durability & Health Monitoring 2023年第3期17卷 239-255页

作者： Zhenqing Shi Guomin Sun Jianyong Pang College of Civil and Architecture Engineering Chuzhou UniversityChuzhouChina Engineering Research Center of Underground Mine Construction Ministry of Education(Anhui University of Science and Technology)HuainanChina

Applying recycled concrete for engineered projects not only protects the ecological environment but also improves the utilization rate of waste concrete to satisfy sustainable development ***,the mechanical properties of recycled concrete are not as good as those of ordinary *** enhance the former’s performance and increase its popularity and application in engineeringﬁelds,notable advances have been made by using steel,synthetic,plant,and mineralﬁber *** materials are added to recycled concrete to improve its mechanical *** have shown that(1)steelﬁbers have a distinct reinforcing effect and improve the strength,toughness,and elastic modulus of recycled concrete;(2)the addition of syntheticﬁbers can improve the tension,crack resistance,and durability of concrete,but the size effect needs to be further explored and elaborated;(3)plantﬁber concrete is lightweight and environmentally friendly and provides high toughness and good thermal insulation,but theﬁbers corrode in alkaline environments;in addition,plantﬁbers have high water absorption capacity,which leads to wet expansion and dry shrinkage phenomena,which need to be further studied;and(4)the cost of basaltﬁber,a mineralﬁber,is relatively low,and a suitable basalt content can improve the mechanical properties of recycled concrete to a certain extent.

关键词： Recycled concrete fibers mechanical properties overview

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