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Performance and environmental impacts of deep foundation excavation in soft soils:A field and modeling-based case study in Nanjing,China

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Underground Space 2024年第5期18卷 218-238页

作者： Chenhe Ge Meng Yang Pengfei Li Mingju Zhang Zhonghao Zhang Key Laboratory of Urban Security and Disaster Engineering Ministry of EducationBeijing University of TechnologyBeijing 100124China China construction Second Engineering Bureau Ltd. Beijing 100070China The Third construction Engineering Company Ltd.of China construction Second Engineering Bureau Beijing 100070China

This paper focuses on the performance of a braced deep excavation in soft soil based on field monitoring and numerical *** tests were conducted to determine the soil parameters used in the modified Cam–Clay(MCC)*** field monitoring means were adopted and a three-dimensional model was *** and temporal effects induced by the excavation are investigated for the deep-large foundation pit in soft *** characteristics of the enclosure structure and the surrounding environment throughout the excavation process are *** behaviors of diaphragm walls,columns,the maximum wall deflection rate,ground surface settlement,and utility pipelines were focused on and investigated during the whole excavation ***,the axial forces of the internal supports are *** on the measured and simulated data,the following main conclusions were obtained:the numerical simulation results are in good agreement with the measured values,which proves the accuracy of the model parameters;the wall and the ground surface showed the maximum displacement increment at stage 9,which was a coupled product of the"creep effect"of the soft soil in Nanjing,China and the"depth effect"of the excavation;as the excavation progressed,the ground settlement changed from a"rising"to a"spoon-shaped"trend,dvm was measured betweenδ_(vm)=0.0686%H andδ_(vm)=0.1488%H;the rebound deformation curve of the pit bottom was corrugated,and the depth of disturbance of the pit bottom after the completion of soil unloading was 2–3 times the excavation depth;the closer the pipeline is to the corner of the pit,the less the excavation process will affect the settlement of the pipeline and the less the obvious pit corner effect will occur;the support strength of the buttress and the longest corner brace should be strengthened during the actual construction process to ensure the stability of the foundation deformation.

关键词： Deep excavation Modified Cam-Clay Deformation characteristics Creep effect Corner effect

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Dynamic response of a thermal transistor to time-varying signals

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Chinese Physics B 2024年第5期33卷 13-19页

作者：阮琴丽刘文君王雷 department of Physics Beijing Key Laboratory of Opto-electronic Functional Materials and Micro-nano Devicesand Key Laboratory of Quantum State Construction and Manipulation (Ministry of Education)Renmin University of ChinaBeijing 100872China

Thermal transistor,the thermal analog of an electronic transistor,is one of the most important thermal devices for microscopic-scale heat *** is a three-terminal device,and the heat current flowing through two terminals can be largely controlled by the temperature of the third *** response plays an important role in the application of electric devices and also thermal devices,which represents the devices’ability to treat fast varying *** this paper,we systematically study two typical dynamic responses of a thermal transistor,i.e.,the response to a step-function input(a switching process)and the response to a square-wave *** role of the length L of the control segment is carefully *** is revealed that when L is increased,the performance of the thermal transistor worsens *** the relaxation time for the former process and the cutoff frequency for the latter one follow the power-law dependence on L quite well,which agrees with our analytical ***,the detailed power exponents deviate from the expected values *** implies the violation of the conventional assumptions that we adopt.

关键词： phonon phononics thermal transistor dynamic response heat conduction

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Vibration attenuation performance of wind turbine tower using a prestressed tuned mass damper under seismic excitation

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Earthquake Engineering and Engineering Vibration 2024年第2期23卷 511-524页

作者： Lei Zhenbo Liu Gang Wang Hui Hui Yi School of Civil Engineering Chongqing UniversityChongqing 400045China Key Laboratory of New Technology for construction of Cities in Mountain Area Chongqing UniversityMinistry of EducationChongqing 400045China

With the rapid development of large megawatt wind turbines,the operation environment of wind turbine towers(WTTs)has become increasingly *** particular,seismic excitation can create a resonance response and cause excessive vibration of the *** investigate the vibration attenuation performance of the WTT under seismic excitations,a novel passive vibration control device,called a prestressed tuned mass damper(PS-TMD),is presented in this ***,a mathematical model is established based on structural dynamics under seismic ***,the mathematical analytical expression of the dynamic coefficient is deduced,and the parameter design method is obtained by system tuning ***,based on a theoretical analysis and parameter design,the numerical results showed that the PS-TMD was able to effectively mitigate the resonance under the harmonic basal ***,the time-history analysis method is used to verify the effectiveness of the traditional pendulum tuned mass damper(PTMD)and the novel PS-TMD device,and the results indicate that the vibration attenuation performance of the PS-TMD is better than the *** addition,the PS-TMD avoids the nonlinear effect due to the large oscillation angle,and has the potential to dissipate hysteretic energy under seismic excitation.

关键词： wind turbine tower prestressed tuned mass damper vibration control seismic excitation numerical simulation

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Semiclassical approach to spin dynamics of a ferromagnetic S = 1 chain

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Chinese Physics B 2024年第6期33卷 95-100页

作者：李承晨崔祎于伟强俞榕 department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials and Micro-nano Devices Renmin University of ChinaBeijing 100872China Key Laboratory of Quantum State construction and Manipulation(Ministry of education) Renmin University of ChinaBeijing 100872China

Motivated by recent experimental progress on the quasi-one-dimensional quantum magnet Ni Nb2O6, we study the spin dynamics of an S = 1 ferromagnetic Heisenberg chain with single-ion anisotropy by using a semiclassical molecular dynamics approach. This system undergoes a quantum phase transition from a ferromagnetic to a paramagnetic state under a transverse magnetic field, and the magnetic response reflecting this transition is well described by our semiclassical *** show that at low temperature the transverse component of the dynamical structure factor depicts clearly the magnon dispersion, and the longitudinal component exhibits two continua associated with single-and two-magnon excitations,respectively. These spin excitation spectra show interesting temperature dependence as effects of magnon interactions. Our findings shed light on the experimental detection of spin excitations in a large class of quasi-one-dimensional magnets.

关键词： one-dimensional ferromagnetism spin dynamics magnon excitation molecular dynamics

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Effect of local openings on bearing behavior and failure mechanism of shield tunnel segments

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Underground Space 2024年第3期16卷 183-205页

作者： Xiaojing Gao Pengfei Li Mingju Zhang Haifeng Wang Ziqi Jia Wu Feng Key Laboratory of Urban Security and Disaster Engineering Ministry of EducationBeijing University of TechnologyBeijing 100124China Nantong Railway construction Component Co. LtdNantong 226000China

Local failures(loss of concrete or reinforcement)can severely compromise the bearing capacity of shield segments,damaging the tunnel *** investigate the effects of local openings on the bearing behavior and failure mechanism,four full-scale bending tests were conducted on specimens with different opening positions and diameters;monitoring of load,displacement,and concrete strain was performed during *** test results reveal that both the opening position and diameter significantly influence the bearing characteristics of the *** failure process includes four sequential stages distinguished by three critical loads,namely the cracking,failure,and ultimate ***,the numerical model of the local failure segment was established using the elastoplastic damage constitutive relation of the concrete and verified by inversing the full-scale test *** on the numerical model,parametric analyses were performed to comprehensively investigate the influences of the opening position,concrete loss,and reinforcement loss on the bending ***,an analytical model was proposed,indicating that the opening position is the primary factor decreasing the bearing capacity,followed by the opening diameter and reinforcement *** results of this study can provide a theoretical basis for the safety assessment and remedial design of subway shield tunnels under extreme breakthrough conditions.

关键词： Shield tunnel Local opening segment Bearing behavior Failure mechanism

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Numerical manifold method for steady-state nonlinear heat conduction using Kirchhoff transformation

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Science China(Technological Sciences) 2024年第4期67卷 992-1006页

作者： ZHANG LiMei KONG Heng ZHENG Hong Key Laboratory of Urban Security and Disaster Engineering Ministry of EducationBeijing University of TechnologyBeijing 100124China Beijing Municipal construction Co. Ltd.Beijing 100048China

The numerical manifold method(NMM)introduces the mathematical and physical cover to solve both continuum and discontinuum problems in a unified *** this study,the NMM for solving steady-state nonlinear heat conduction problems is presented,and heat conduction problems consider both convection and radiation boundary ***,the nonlinear governing equation of thermal conductivity,which is dependent on temperature,is transformed into the Laplace equation by introducing the Kirchhoff *** transformation reserves linearity of both the Dirichlet and the Neumann boundary conditions,but the Robin and radiation boundary conditions remain ***,the NMM is employed to solve the Laplace equation using a simple iteration procedure because the nonlinearity focuses on parts of the problem domain ***,the temperature field is retrieved through the inverse Kirchhoff *** examples are analyzed,demonstrating the advantages of the Kirchhoff transformation over the direct solution of nonlinear equations using the NewtonRaphson *** study provides a new method for calculating nonlinear heat conduction.

关键词： numerical manifold method nonlinear heat conduction temperature-dependent thermal conductivity Kirchhoff transformation convection and radiation boundary conditions

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Relationship between disorder,magnetism and band topology in Mn(Sb_(1-x)Bi_(x))_(2)Te_(4) single crystals

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Chinese Physics B 2024年第6期33卷 102-107页

作者：席明雷和畅 department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials&Micro-nano Devices Renmin University of ChinaBeijing 100872China Key Laboratory of Quantum State construction and Manipulation(Ministry of education) Renmin University of ChinaBeijing 100872China

We investigate the evolution of magnetic properties as well as the content and distribution of Mn for Mn(Sb_(1-x)Bi_(x))_(2)Te_(4) single crystals grown by large-temperature-gradient chemical vapor transport *** is found that the ferromagnetic MnSb_(2)Te_(4) changes to antiferromagnetism with Bi doping when x≥*** analysis implies that the occupations of Mn ions at Sb/Bi site Mn_(Sb/Bi) and Mn site Mn_(Mn) have a strong influence on the magnetic ground states of these *** the decrease of Mn_(Mn) increase of Mn_(Sb/Bi),the system will favor the ferromagnetic ground *** addition,the rapid decrease of T_(C/N) with increasing Bi content when x ≤0.25 and the insensitivity of T_(N) to x when x> 0.25 suggest that the main magnetic interaction may change from the Ruderman-Kittel-Kasuya-Yosida type at low Bi doping region to the van-Vleck type in high Bi doped samples.

关键词： magnetic topological insulator magnetic properties antisite defects chemical vapor transport

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Langmuir-Schaefer Film Investigation and Density Functional Theory Band Gap Calculations of Calix[n]arene-Para-Aminobenzoic Acid for Drug Nanosensor Application

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Journal of Wuhan University of Technology(Materials Science) 2024年第5期39卷 1311-1318页

作者： WONG Yeong Yi F L Supian A Radzwan M Musa N F N Abd Karim department of Physics Sultan Idris Education UniversityTanjong Malim 35900Malaysia department of Chemistry Sultan Idris Education UniversityTanjong Malim 35900Malaysia

Calix[n]arenes was utilized to detect PABA,the primary sunscreen *** study investigates the interaction of calix[4]arene(C4),calix[6]arene(C6),and PABA using the Langmuir method and first-principle density functional theory(DFT).Using the Langmuir-Schaefer(LS)technique,an ultrathin film composed of calix[n]arenes and their complexes with PABA was deposited on various *** on the Langmuir study,the PABA molecule was bonded to the lower rims of both C4 and C6 with the host-guest ratio of 1:*** of the LS films formed were then characterized by ultravioletvisible spectroscopy(UV-Vis),Fourier-transform infrared spectroscopy(FTIR)and carbon,hydrogen,nitrogen,sulfur elemental analyzer(CHNS).The band gap reduction obtained in the DFT study denotes the charge transfer interaction with promising reactivity between the calix[n]arenes and *** sensing of PABA by C4 and C6 is successful based on the formation of bonding between them due to the hosts’effective trapping *** outcomes of this study could be applied to drug delivery systems for future pharmaceutical and medical applications.

关键词： calix[n]arenes band gap density functional theory Langmuir-Schaefer PABA sensor

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On the calibration of a shear stress criterion for rock joints to represent the full stress-strain profile

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第2期16卷 379-392页

作者： Akram Deiminiat Jonathan D.Aubertin Yannic Ethier department of construction Engineering École de Technologie Supérieure(ÉTS)MontréalCanada

Conventional numerical solutions developed to describe the geomechanical behavior of rock interfaces subjected to differential load emphasize peak and residual shear *** detailed analysis of preand post-peak shear stress-displacement behavior is central to various time-dependent and dynamic rock mechanic problems such as rockbursts and structural instabilities in highly stressed *** complete stress-displacement surface(CSDS)model was developed to describe analytically the pre-and post-peak behavior of rock interfaces under differential *** formulations of the CSDS model required extensive curve-fitting iterations which limited its practical applicability and transparent integration into engineering *** present work proposes modifications to the CSDS model aimed at developing a comprehensive and modern calibration protocol to describe the complete shear stressdisplacement behavior of rock interfaces under differential *** proposed update to the CSDS model incorporates the concept of mobilized shear strength to enhance the post-peak ***’s concepts of joint roughness coefficient(JRC)and joint compressive strength(JCS)are incorporated to facilitate empirical estimations for peak shear stress and normal closure ***/uniaxial compression test and direct shear test results are used to validate the updated model and exemplify the proposed calibration *** results illustrate that the revised model successfully predicts the post-peak and complete axial stressestrain and shear stressedisplacement curves for rock joints.

关键词： Full shear profile Post-peak shear behavior Rock joint Joint roughness coefficient(JRC) Axial stress-strain curve

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Public perception of connected and automated vehicles:Benefits,concerns,and barriers from an Australian perspective

Journal of Intelligent and Connected Vehicles

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Journal of Intelligent and Connected Vehicles 2024年第2期7卷 108-128页

作者： Ali Matin Hussein Dia department of Civil and construction Engineering Swinburne University of TechnologyMelbourne 3122Australia

This study investigates the attitudes and concerns of the Australian public toward connected and autonomous vehicles(CAVs),and the factors influencing their willingness to adopt this *** a comprehensive survey,a diverse group of respondents provided valuable insights toward various CAV scenarios such as riding in a vehicle with no driver,self-driving public transport,self-driving taxis,and heavy vehicles without *** results highlight the significant impact of safety concerns about automated vehicles on individuals’attitudes across all *** levels of concern were associated with more negative attitudes,and a strong correlation between concerns and opposition underlines the necessity of addressing these apprehensions to build public trust and promote CAV ***,nearly 70%of respondents felt uncomfortable driving next to a CAV,but they displayed more confidence in adopting automated public transport in the near ***,around 40%of participants indicated a strong willingness to purchase a CAV,primarily driven by the desire to reduce their carbon footprint and safety ***,respondents with health conditions or disability exhibited heightened interest(almost double those without health conditions)in CAV *** differences emerged in attitudes and preferences toward CAVs,with women expressing a greater level of concern and perceiving higher barriers to CAV *** emphasizes the importance of employing targeted approaches to address the specific concerns of different *** study also underscores the role of trust in technology as a significant barrier to CAV deployment,ranking high among respondents’*** overcome these challenges and facilitate successful CAV deployment,various strategies are suggested,including live demonstrations,dedicated routes for automated public transport,adoption incentives,and addressing liability *** findings from this st

关键词： connected and automated vehicles(CAVs) autonomous vehicles public acceptance stakeholder consultations road safety

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