Flexible PANI-Polyethersulfone (PES) fibers were fabricated using the wet-spinning technique.PANI particles were uniformly distributed within the matrix and micropores formed by the phase separation of PES,which preve...Flexible PANI-Polyethersulfone (PES) fibers were fabricated using the wet-spinning technique.PANI particles were uniformly distributed within the matrix and micropores formed by the phase separation of PES,which prevented PANI particles aggregation and facilitated the formation of continuous ion transport channels.The experimental results reveals that the electrochemical performance of the fiber electrode material is optimal when the concentration of PES in the spinning solution is 15wt%.The assembled supercapacitor exhibits a commendable specific area capacitance of 162.75 mF·cm^(-2) at a current density of 0.5 mA·cm^(-2) and achieves an energy density of 14.47 mWh·cm^(-2) at a power density of 321.69 mW·cm^(-2).The capacitor retains 98.1% of its capacitance after 1 000 bending cycles.Therefore,the prepared fibers have good electrochemical properties and flexibility,and this simple and efficient preparation method is promising for the scalable production of flexible electrodes.展开更多
There are two major challenges faced by modern society:energy security,and lowering carbon dioxide gas emissions.Thermo-active diaphragm walls have a large potential to remedy one of these problems,since they are a re...There are two major challenges faced by modern society:energy security,and lowering carbon dioxide gas emissions.Thermo-active diaphragm walls have a large potential to remedy one of these problems,since they are a renewable energy technology that uses underground infrastructure as a heat exchange medium.However,extensive research is required to determine the effects of cyclic heating and cooling on their geotechnical and structural performance.In this paper,a series of detailed finite element analyses are carried out to capture the fully coupled thermo-hydro-mechanical response bf the ground and diaphragm wall.It is demonstrated that the thermal operation of the diaphragm wall causes changes in soil temperature,thermal expansion/shrinkage of pore water,and total stress applied on the diaphragm wall.These,in turmn,cause displacements of the diaphragm wall and variations of the bending moments.However,these effects on the performance of diaphragm wall are not significant.The thermally induced bending strain is mainly governed by the temperature differential and uneven thermal expansion/shrinkage across the wall.展开更多
Calcareous sand is widely observed in the foundation of off-shore infrastructure.Although a lot of research has been carried out on the mechanical properties of calcareous sand,study into the influence of the stress–...Calcareous sand is widely observed in the foundation of off-shore infrastructure.Although a lot of research has been carried out on the mechanical properties of calcareous sand,study into the influence of the stress–strain path on the mechanical behaviour of calcareous sand is very limited.In this study,a series of triaxial tests were performed on calcareous sand under three different stress paths.The particle morphology of calcareous sand before and after the tests,the stress–strain relationship under different stress paths,and the char-acteristics of shear strength and deformation were investigated.The results show that the consolidation pressure and stress path have significant effects on the volume strain,strength,and particle breakage of calcareous sand.In addition,the underlying mechanisms of the different behaviours of calcareous sand observed in this study were discussed.展开更多
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 t...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 London.Being 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 anomalies.The 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 loads.Based on this pile load test,a finite element(FE)analysis was performed using a one-dimensional nonlinear load-transfer model.Calibrated 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 accuracy.The 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%.展开更多
Geothermal energy is a kind of green and renewable energy.Conventionally,ground source heat pumps can be used to harvest geothermal energy from the subsurface.To reduce the initial investment,a good solution is to use...Geothermal energy is a kind of green and renewable energy.Conventionally,ground source heat pumps can be used to harvest geothermal energy from the subsurface.To reduce the initial investment,a good solution is to use tunnel linings as heat exchangers to extract/dump heat.This special infrastructure is called an energy tunnel.In addition to the thermal performance,the impact of pipe network configuration on thermal efficiency is still challenging in the design of energy tunnels.To 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 ground.On the other hand,the influence of 3 various heat-carrying pipes layout is also investigated.It is found that higher heat transfer efficiency can be obtained when the entrance and exit of pipelines are located below the tunnel in the study.The spatial location of pipelines will also affect the exchanged heat output.展开更多
When the shield tunnel passes through the gas-bearing strata,gas and water leakage may occur depending on the sealing performance of the segment joints.This process involves the complex multiphase seepage flow phenome...When the shield tunnel passes through the gas-bearing strata,gas and water leakage may occur depending on the sealing performance of the segment joints.This process involves the complex multiphase seepage flow phenomenon in unsaturated soil.In 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 joints.The constitutive model of the Extended Barcelona Basic Model was imple-mented to simulate the effect of the seepage process on soil deformation.The results show that significant upward displacement occurred in the gas reservoir and its overlying strata,and the maximum displacement reached 30 mm.In addition,during the leakage of the gas and the water,an increase in the average soil effective stress was observed.It would induce a reduction in the suction and expansion of the yield surface.The tunnel tended to be stable from 20 years onwards,thus the soil deformation due to the water leakage only occurred at the early stage.In 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 limit.The results of this study help to understand the influence of high-pressure gas on tunnel safety and the sealing performance of the joints.展开更多
Tunnels constructed in gas-bearing strata are affected by the potential leakage of harmful gases,such as methane gas.Based on the basic principles of computational fluid dynamics,a numerical analysis was performed to ...Tunnels constructed in gas-bearing strata are affected by the potential leakage of harmful gases,such as methane gas.Based 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 evaluated.As 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 channels.The influence of increased ventilation airflow velocity was dominant for the ventilation modes with two and four fans.In addition,laboratory tests on methane leakage through segment joints were performed.The 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 deformation.Based 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.展开更多
基金Funded by the Hubei Integrative Technology and Innovation Center for Advanced Fiberous Materials Open Fund (No.XC202425)。
文摘Flexible PANI-Polyethersulfone (PES) fibers were fabricated using the wet-spinning technique.PANI particles were uniformly distributed within the matrix and micropores formed by the phase separation of PES,which prevented PANI particles aggregation and facilitated the formation of continuous ion transport channels.The experimental results reveals that the electrochemical performance of the fiber electrode material is optimal when the concentration of PES in the spinning solution is 15wt%.The assembled supercapacitor exhibits a commendable specific area capacitance of 162.75 mF·cm^(-2) at a current density of 0.5 mA·cm^(-2) and achieves an energy density of 14.47 mWh·cm^(-2) at a power density of 321.69 mW·cm^(-2).The capacitor retains 98.1% of its capacitance after 1 000 bending cycles.Therefore,the prepared fibers have good electrochemical properties and flexibility,and this simple and efficient preparation method is promising for the scalable production of flexible electrodes.
文摘There are two major challenges faced by modern society:energy security,and lowering carbon dioxide gas emissions.Thermo-active diaphragm walls have a large potential to remedy one of these problems,since they are a renewable energy technology that uses underground infrastructure as a heat exchange medium.However,extensive research is required to determine the effects of cyclic heating and cooling on their geotechnical and structural performance.In this paper,a series of detailed finite element analyses are carried out to capture the fully coupled thermo-hydro-mechanical response bf the ground and diaphragm wall.It is demonstrated that the thermal operation of the diaphragm wall causes changes in soil temperature,thermal expansion/shrinkage of pore water,and total stress applied on the diaphragm wall.These,in turmn,cause displacements of the diaphragm wall and variations of the bending moments.However,these effects on the performance of diaphragm wall are not significant.The thermally induced bending strain is mainly governed by the temperature differential and uneven thermal expansion/shrinkage across the wall.
基金supported by the National Natural Science Foundation of China(Grant Nos.41877260,41772336).
文摘Calcareous sand is widely observed in the foundation of off-shore infrastructure.Although a lot of research has been carried out on the mechanical properties of calcareous sand,study into the influence of the stress–strain path on the mechanical behaviour of calcareous sand is very limited.In this study,a series of triaxial tests were performed on calcareous sand under three different stress paths.The particle morphology of calcareous sand before and after the tests,the stress–strain relationship under different stress paths,and the char-acteristics of shear strength and deformation were investigated.The results show that the consolidation pressure and stress path have significant effects on the volume strain,strength,and particle breakage of calcareous sand.In addition,the underlying mechanisms of the different behaviours of calcareous sand observed in this study were discussed.
基金The authors thank the EPSRC and Innovate UK for funding this research through the Cambridge Centre for Smart Infrastructure and Construction(CSIC)Innovation and Knowledge Centre(EPSRC grand reference number EP/L010917/1)We thank Professor Kenichi Soga(UC Berkeley)for providing valuable input to this research.We would also like to acknowledge the contribution of Angus Cameron from Environmental Scientifics Group.
文摘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 London.Being 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 anomalies.The 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 loads.Based on this pile load test,a finite element(FE)analysis was performed using a one-dimensional nonlinear load-transfer model.Calibrated 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 accuracy.The 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%.
基金supported by the Royal Society Inter-national Exchange,China(Grant No.IES\R1\211092)the China Postdoctoral Science Foundation(Grant No.2019M651580).
文摘Geothermal energy is a kind of green and renewable energy.Conventionally,ground source heat pumps can be used to harvest geothermal energy from the subsurface.To reduce the initial investment,a good solution is to use tunnel linings as heat exchangers to extract/dump heat.This special infrastructure is called an energy tunnel.In addition to the thermal performance,the impact of pipe network configuration on thermal efficiency is still challenging in the design of energy tunnels.To 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 ground.On the other hand,the influence of 3 various heat-carrying pipes layout is also investigated.It is found that higher heat transfer efficiency can be obtained when the entrance and exit of pipelines are located below the tunnel in the study.The spatial location of pipelines will also affect the exchanged heat output.
文摘When the shield tunnel passes through the gas-bearing strata,gas and water leakage may occur depending on the sealing performance of the segment joints.This process involves the complex multiphase seepage flow phenomenon in unsaturated soil.In 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 joints.The constitutive model of the Extended Barcelona Basic Model was imple-mented to simulate the effect of the seepage process on soil deformation.The results show that significant upward displacement occurred in the gas reservoir and its overlying strata,and the maximum displacement reached 30 mm.In addition,during the leakage of the gas and the water,an increase in the average soil effective stress was observed.It would induce a reduction in the suction and expansion of the yield surface.The tunnel tended to be stable from 20 years onwards,thus the soil deformation due to the water leakage only occurred at the early stage.In 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 limit.The results of this study help to understand the influence of high-pressure gas on tunnel safety and the sealing performance of the joints.
基金funded by the China Postdoctoral Science Foundation(No.2019M651580)the Research Project of the Chinese National Major Scientific Instrument and Equipment Development(No.41827807)。
文摘Tunnels constructed in gas-bearing strata are affected by the potential leakage of harmful gases,such as methane gas.Based 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 evaluated.As 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 channels.The influence of increased ventilation airflow velocity was dominant for the ventilation modes with two and four fans.In addition,laboratory tests on methane leakage through segment joints were performed.The 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 deformation.Based 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.
