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Study on the long-term performance of shield tunnel passing through the gas-bearing strata

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Underground Space 2023年第2期9卷 1-19页

作者： Jie He Xiangyang Wei mei yin College of Civil Engineering Tongji UniversityShanghai 200092China State Key Laboratory for Disaster Reduction in Civil Engineering Tongji UniversityShanghai 200092China Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji UniversityShanghai 200092China Civil and Environmental Engineering Department Brunel University LondonLondon UB83PHUK Recei

When the shield tunnel passes through the gas-bearing strata,gas and water leakage may occur depending on the sealing performance of the segment *** process involves the complex multiphase seepage flow phenomenon in unsaturated *** this study,a fully coupled solid-liquid-gas model of the GIL Utility Tunnel was established to investigate the influence of the high-pressure gas on the mechanical properties of the tunnel segments and *** constitutive model of the Extended Barcelona Basic Model was imple-mented to simulate the effect of the seepage process on soil *** results show that significant upward displacement occurred in the gas reservoir and its overlying strata,and the maximum displacement reached 30 *** addition,during the leakage of the gas and the water,an increase in the average soil effective stress was *** would induce a reduction in the suction and expansion of the yield *** tunnel tended to be stable from 20 years onwards,thus the soil deformation due to the water leakage only occurred at the early *** addition,the joint opening under the most unfavorable internal force combination was 0.69 mm,and the correspond-ing bolt stress was 119.5 MPa,which is below the yield *** results of this study help to understand the influence of high-pressure gas on tunnel safety and the sealing performance of the joints.

关键词： A coupled solid-liquid-gas model Unsaturated soil Multiphase seepage Gas-bearing strata Shield tunnel FEM

Optimization of pipe circuits in energy tunnels

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Underground Space 2023年第6期13卷 166-182页

作者： Jie He mei yin Xiangyang Wei Zhenhuang Wu College of Civil Engineering Tongji UniversityShanghai 200092China Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji UniversityShanghai 200092China Department of Civil and Environmental Engineering Brunel UniversityUxbridgeLondon UB83PHUK

Geothermal energy is a kind of green and renewable ***,ground source heat pumps can be used to harvest geothermal energy from the *** reduce the initial investment,a good solution is to use tunnel linings as heat exchangers to extract/dump *** special infrastructure is called an energy *** addition to the thermal performance,the impact of pipe network configuration on thermal efficiency is still challenging in the design of energy *** solve this problem,this study makes the first attempt to carry out research on the optimization of pipe circuits in energy tunnels by a series of numerical analyses.A fully coupled thermo-hydraulic 3D finite element model is established to investigate the response of tunnel-soil interaction under cyclical thermal loading(initial soil temperature varies from 8C to 18C),as well as the thermal transient interactions among air,absorber pipe,tunnel linings and ground,to quantify the amount of useful heat that can be extracted from the tunnel and the *** the other hand,the influence of 3 various heat-carrying pipes layout is also *** is found that higher heat transfer efficiency can be obtained when the entrance and exit of pipelines are located below the tunnel in the *** spatial location of pipelines will also affect the exchanged heat output.

关键词： Energy tunnel Thermal efficiency Finite element model Heat transfer

Prediction of three-dimensional elastic behavior of filament-wound composites based on the bridging model

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Defence Technology（防务技术） 2021年第2期17卷 609-616页

作者： Dong-mei yin Bao-ming Li Hong-cheng Xiao National Key Laboratory of Transient Physics Nanjing University of Science&TechnologyNanjing210094China

This work provides a method to predict the three-dimensional equivalent elastic properties of the filament-wound composites based on the multi-scale homogenization *** the meso-scale,a representative volume element(RVE)is defined and the bridging model is adopted to establish a theoretical predictive model for its three-dimensional equivalent elastic *** results obtained through this method for the previous experimental model are compared with the ones gained respectively by experiments and classical laminate theory to verify the reliability of this *** addition,the effects of some winding parameters,such as winding angle,on the equivalent elastic behavior of the filament-wound composites are *** rules gained can provide a theoretical reference for the optimum design of filament-wound composites.

关键词： Lightweight design Filament-wound composites Bridging model Three-dimensional elastic properties

Analysis for the residual prestress of composite barrel for railgun with tension winding

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Defence Technology（防务技术） 2020年第4期16卷 893-899页

作者： Dong-mei yin Bao-ming Li Hong-cheng Xiao National Key Laboratory of Transient Physics Nanjing University of Science&TechnologyNanjing210094China

Based on the elastic theory of cylindrical shells and the theory of composite laminates,a prediction model for the residual prestress of the simplified round composite barrel for railgun is *** the fibre pretension is considered in this model.A three dimensional numerical simulation for the residual prestress in the railgun barrel is carried out,by combining the temperature differential method with the element birth and death *** results obtained by the two methods are *** reveals that the distribution trends of residual prestress are *** the difference for residual prestress in the filament wound composite housing of barrel is relatively *** same finite element method is used to analysis the residual prestress in the non-simplified composite barrels for railgun,which are under different control modes of winding *** results mean that the residual prestress in barrel will increase while the taper coefficient for winding is ***,the sealing performance in bore is improved,but the strength of the filament wound composite housing *** addition,the axial and circumferential residual prestress in the filament wound composite housing with constant torque winding are close to the ones in iso-stress design for barrel.

关键词： Railgun Barrel Composite materials Filament winding Winding tension Residual prestress

Electrodynamic response study on railgun launcher based on electromechanical coupling model

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Defence Technology（防务技术） 2019年第4期15卷 655-665页

作者： Hong-cheng Xiao Dong-mei yin Bao-ming Li National Key Laboratory of Transient Physics Nanjing University of Science and Technology

The electrodynamic behavior of a medium caliber railgun launcher has been studied based on an electromechanical coupling model,which uses a unified modeling method for both electromagnetic and electromechanical *** model adopts a material equivalent method to simulating the sliding contact behavior for the in-bore *** embedded node encoding program during field meshing operation provides good load transfer accuracy between electromagnetic field and mechanical *** properties of in-bore magnetic field are firstly simulated and a subsequent dynamic analysis is conducted by mapping element results from electromagnetic analysis step to structure analysis *** electromechanical-elastic response of the barrel is studied under the excitation *** numerical model has shown reliability compared to experimental results.

关键词： Railgun launcher Sliding contact Dynamic properties Elastic response

Novel Nano-composites SDC–LiNaSO_4 as Functional Layer for ITSOFC

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Nano-Micro Letters 2015年第3期7卷 268-275页

作者： Weiming Lv Ze Tong Yi-mei yin Jiewei yin Zi-Feng Ma Shanghai Electrochemical Energy Devices Research Center School of Chemistry and Chemical Engineering Shanghai Jiao Tong University Shanghai Research and Development Center for Polymer Materials

As an ionic conductive functional layer of intermediate temperature solid oxide fuel cells(ITSOFC), samarium-doped ceria(SDC)–Li Na SO4nano-composites were synthesized by a sol–gel method and their properties were investigated. It was found that the content of Li Na SO4 strongly affected the crystal phase, defect concentration, and conductivity of the composites. When the content of Li Na SO4 was 20 wt%, the highest conductivity of the composite was found to be, respectively, 0.22, 0.26, and 0.35 S cm-1at temperatures of 550, 600, and 700 °C, which are much higher than those of SDC. The peak power density of the single cell using this composite as an interlayer was improved to, respectively, 0.23, 0.39, and 0.88 W cm-2at 500, 600, and 700 °C comparing with that of the SDC-based cell. Further, the SDC–Li Na SO4(20 wt%)-based cell also displayed better thermal stability according to the performance measurements at 560 °C for 50 h. These results reveal that SDC–Li Na SO4 composite may be a potential good candidate as interlayer for ITSOFC due to its high ionic conductivity and thermal stability.

关键词： Nano-composite SDC–Li Na SO4 Ionic conductor Solid oxide fuel cell

Interference Pattern of Density-Density Correlation for Incoherent Atoms with Vortices Released from an Optical Lattice

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Chinese Physics Letters 2011年第1期28卷 26-29页

作者： XU Zhi-Jun ZHANG Dong-mei LIU Xia-yin College of Science Zhejiang University of Technology Hangzhou 310023

For a series of incoherent condensate atomic clouds with vortices （an orbital angular momentum） released from an optical lattice, the density-density correlation function of this freely expanding ultracold gases is theoretically investigated. It is shown that the nonzero angular momentum of the atoms has an important effect on the fringe pattern of density-density correlation. Particularly, for a short expansion time, even the rotation direction of the atoms could have an observable effect on the fringe pattern. Observation of this specific fringe pattern would constitute experimental evidence for the presence of a vortex in an atomic condensate.

关键词： Quantum gases, liquids and solids Optics, quantum optics and lasers Statistical physics and nonlinear systems

Distributed fiber optic monitoring of a CFA pile with a central reinforcement bar bundle

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Frontiers of Structural and Civil Engineering 2021年第1期15卷 167-176页

作者： Yi RUI Nicholas de BATTISTA Cedric KECHAVARZI Xiaomin XU mei yin Centre for Smart Infrastructure and Construction Department of EngineeringUniversity of CambridgeCambridge CB21TNUK Department of Engineering University of CambridgeCambridge CB21TNUK

In this paper,we present an application of distributed fiber optic sensor(DFOS)technology to measure the strain of a continuous flight auger(CFA)test pile with a central reinforcement bar bundle,during a static load test carried out in *** distributed in nature,DFOS gives much more information about the pile performance as compared to traditional point sensors,such as identifying cross-sectional irregularities or other *** strain profiles recorded along the depth of the piles from the DFOS were used to calculate pile deformation(contraction),shaft friction,and tip resistance under various *** on this pile load test,a finite element(FE)analysis was performed using a one-dimensional nonlinear load-transfer *** by the shaft friction and tip resistance derived from the monitored data,the FE model was able to simulate the pile and soil performance during the load testing with good *** effect of the reinforcement cage and central reinforcement bar bundle were investigated,and it was found that the addition of a reinforcement cage would reduce the pile settlement by up to 20%.

关键词： continuous flight auger pile static load test central reinforcement bar bundle distributed fiber optic sensor finite element load transfer

Numerical and experimental analyses of methane leakage in shield tunnel

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Frontiers of Structural and Civil Engineering 2023年第7期17卷 1011-1020页

作者： Jie HE Hehua ZHU Xiangyang WEI Rui JIN Yaji JIAO mei yin College of Civil Engineering Tongji UniversityShanghai 200092China State Key Laboratory for Disaster Reduction in Civil Engineering Tongji UniversityShanghai 200092China Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji UniversityShanghai 200092China d Department of Civil and Environmental EngineeringBrunel UniversityLondon UB83PHUK

Tunnels constructed in gas-bearing strata are affected by the potential leakage of harmful gases,such as methane *** on the basic principles of computational fluid dynamics,a numerical analysis was performed to simulate the ventilation and diffusion of harmful gases in a shield tunnel,and the effect of ventilation airflow speed on the diffusion of harmful gases was *** the airflow speed increased from 1.8 to 5.4 m/s,the methane emission was diluted,and the methane accumulation was only observed in the area near the methane leakage *** influence of increased ventilation airflow velocity was dominant for the ventilation modes with two and four *** addition,laboratory tests on methane leakage through segment joints were *** results show that the leakage process can be divided into“rapid leakage”and“slight leakage”,depending on the leakage pressure and the state of joint *** on the numerical and experimental analysis results,a relationship between the safety level and the joint deformation is established,which can be used as guidelines for maintaining utility tunnels.

关键词： shield tunnel harmful gas leakage numerical analysis laboratory test