Tea flavor is a comprehensive representation of its aroma and other characteristics.The formation of volatile odor compounds during tea processing depends on a variety of enzymatic and non-enzymatic activities.(Z)-3-h...Tea flavor is a comprehensive representation of its aroma and other characteristics.The formation of volatile odor compounds during tea processing depends on a variety of enzymatic and non-enzymatic activities.(Z)-3-hexenol is considered the primary source of the green odor and is also the most important component in tea aroma,significantly affecting the overall aroma.However,the biosynthesis and accumulation of(Z)-3-hexenol during tea processing have not been fully analyzed.In this study,we found that withering treatment at different times and withering plus shaking treatment at different degrees promoted the accumulation of important volatile components of green tea odor,especially(Z)-3-hexenol by GC-MS.The RNA-seq and qRT-PCR results showed that withering and withering plus shaking treatments enhanced the expression of(Z)-3-hexenol-related genes in tea leaves,including synthetic pathway 1 genes(CsLOX3,CsHPL1,CsADH4,and CsAHD1),synthetic pathway 2 genes(CsGLU),and synthetic pathway 3 genes(CsCXEs).Correlation analysis of the key odorants and important genes in the three synthetic pathways revealed that some CsCXEs were positively correlated with green odor compounds.The in vitro enzyme activity results showed that rCsCXE3(GWHTASIV011658),and rCsCXE6(GWHTASIV031480)exhibited hydrolytic activity against three tea acetate compounds[hexyl acetate,(E)-2-hexyl acetate,and(Z)-3-hexyl acetate],resulting in the production of corresponding alcohol compounds.In summary,withering and shaking treatment during tea processing promoted the expression of CsCXE3 and CsCXE6,thereby enhancing the production of hexenol compounds.These compounds play a crucial role in increasing the green odor of tea.展开更多
The present study investigates the influence of embedment depth of isolated footing supporting moment-resisting frame buildings through scaled-down tests.These experiments utilize scaled models representing different ...The present study investigates the influence of embedment depth of isolated footing supporting moment-resisting frame buildings through scaled-down tests.These experiments utilize scaled models representing different building aspect ratios and footing embedment depths.All the model tests are subjected to scaled-down input ground motions of different intensities and magnitudes.These model tests are performed in laminar shear containers through shake table testing.The results obtained for different cases of soil-foundation-structure systems and fixed-base conditions are expressed in terms of natural frequency,peak spectral acceleration,frequency response,lateral deformation,inter-storey drifts,and rocking of the foundation.The analysis reveals that the natural frequency of the coupled system on isolated footings diminishes by 27.52%–58.21%relative to fixed-base conditions,highlighting the significance of accounting for soil-foundation-structure interaction effects.Moreover,a notable increase of 52.97%in the natural frequency of the coupled system is observed as the embedment depth of the footing increases from 0.75 to 6.Additionally,the study demonstrates that the inter-storey drift of the 5-storey building remains well within acceptable limits under dense soil conditions.Consequently,within the parameter range explored in this research,the study concludes that soil-foundation-structure interaction effects are insignificant for low-rise buildings(H≤15 m)supported on isolated footings during seismic events.展开更多
Seismic-induced landslides critically threaten infrastructure and human safety,especially in sandy slopes where conventional stabilization methods often fail under dynamic loading.This study evaluates circular open-en...Seismic-induced landslides critically threaten infrastructure and human safety,especially in sandy slopes where conventional stabilization methods often fail under dynamic loading.This study evaluates circular open-ended anti-slide pipe piles embedded in a two-layer sandy slope with differing geotechnical properties.Ten physical models,including five freefield and five pile-reinforced slopes,were tested on a shaking table.Key seismic responses—acceleration,soil displacement,and bending moments—were monitored using accelerometers,strain gauges,and Digital Image Correlation(DIC).Complementary numerical simulations using Abaqus with a Mohr–Coulomb model validated experimental results.Soil displacement in free-field models under 0.25g shaking was about 3.5 times greater than in reinforced slopes.Bending moments increased with seismic intensity,peaking at depths around five times the pile diameter.Limitations including simplified two-layer soil representation,idealized seismic inputs,and boundary effects inherent to laboratory models restrict direct field application but enable controlled analysis.By combining physical experiments with numerical modeling,the study provides a robust and validated framework for seismic slope stabilization.This integrated approach enhances understanding of soil–pile interaction under seismic loads and offers targeted insights for developing safer and more reliable geotechnical design strategies in earthquake-prone areas.展开更多
This article primarily establishes a two-soliton system and employs the Lewis-Riesenfeld invariant inverse control method to achieve shortcuts to adiabaticity(STA)technology.We study an atomic soliton Josephson juncti...This article primarily establishes a two-soliton system and employs the Lewis-Riesenfeld invariant inverse control method to achieve shortcuts to adiabaticity(STA)technology.We study an atomic soliton Josephson junctions(SJJs)device and subsequently compare and analyze it with atomic bosonic Josephson junctions.Moreover,we use higher-order expressions of the auxiliary equations to optimize the results and weaken the detrimental effect of the sloshing amplitude.We find that in the adiabatic shortcut evolution of two systems with time-containing tunnelling rates,the SJJs system is more robust over a rather short time evolution.In comparison with linear ramping,the STA technique is easier to achieve with the precise modulation of the quantum state in the SJJs system.展开更多
Weak interlayers play a crucial role in the seismic performance of bedding slopes;however,the effects of structural surface development within these layers remain underexplored.This study presents two scaled models of...Weak interlayers play a crucial role in the seismic performance of bedding slopes;however,the effects of structural surface development within these layers remain underexplored.This study presents two scaled models of bedding slopes,each with different weak interlayers:one with a homogeneous weak layer and another with discontinuous interfaces.Shaking table tests were conducted to compare their seismic performance.The results show that the peak ground acceleration(PGA)values above the weak interlayer in model A were significantly higher than those in model B,with the differences increasing as the input wave amplitude increased.The peak earth pressure(PEP)values at the tensile failure boundary at the rear edge of model A were also higher,whereas those within the weak layer at the toe of model A were lower than those in model B.Deformation analysis revealed that the maximum principal strain in model A initially appeared at the upper part of the tensile failure boundary,while the maximum shear strain was concentrated near the rear edge within the weak layer.In contrast,model B exhibited the opposite strain distribution.These findings provide insight into the impact of weak interlayers on the dynamic response and deformation of bedding slopes,highlighting the importance of considering this factor in seismic landslide investigations and failure mode predictions.展开更多
A fault is a geological structure characterized by significant displacement of rock masses along a fault plane within the Earth's crust.The Yunnan Tabaiyi Tunnel intersects multiple fault zones,making tunnel const...A fault is a geological structure characterized by significant displacement of rock masses along a fault plane within the Earth's crust.The Yunnan Tabaiyi Tunnel intersects multiple fault zones,making tunnel construction in fault-prone areas particularly vulnerable to the effects of fault activity due to the complexities of the surrounding geological environment.To investigate the dynamic response characteristics of tunnel structures under varying surrounding rock conditions,a three-dimensional large-scale shaking table physical model test was conducted.This study also aimed to explore the damage mechanisms associated with the Tabaiyi Tunnel under seismic loading.The results demonstrate that poor quality surrounding rock enhances the seismic response of the tunnel.This effect is primarily attributed to the distribution characteristics of acceleration,dynamic strain,and dynamic soil pressure.A comparison between unidirectional and multi-directional(including vertical)seismic motions reveals that vertical seismic motion has a more significant impact on specific tunnel locations.Specifically,the maximum tensile stress is observed at the arch shoulder,with values ranging from 60 to 100 k Pa.Moreover,NPR(Non-Prestressed Reinforced)anchor cables exhibit a substantial constant resistance effect under low-amplitude seismic waves.However,when the input earthquake amplitude reaches 0.8g,local sliding occurs at the arch shoulder region of the NPR anchor cable.These findings underscore the importance of focusing on seismic mitigation measures in fault zones and reinforcing critical areas,such as the arch shoulders,in practical engineering applications.展开更多
Seismic-induced liquefaction of sandy soils can fail foundations in the vicinity of buildings.To investigate the effect of a non-free field subsurface seismic history on the ability of saturated sandy soils to resist ...Seismic-induced liquefaction of sandy soils can fail foundations in the vicinity of buildings.To investigate the effect of a non-free field subsurface seismic history on the ability of saturated sandy soils to resist liquefaction,four shaking events with different accelerations were input to the sandy soils in the non-free-field.The results of the study revealed that:(1)Shallow soils that are not free-field undergo acceleration amplification effects after being subjected to seismic loading.(2)Building overburden pressure reduces the sensitivity of the shallow soils directly below in small and moderate earthquakes,which are more prone to rearranging and forming unstable structures under strong seismic effects.The excess pore pressure response on the load side resembles that of a free site,with the depth range of the liquefaction strength of soils affected by the seismic history,increasing progressively as input seismic intensity increases.(3)After experiencing earthquakes of different intensities,the excess pore pressure directly below the building overburden pressure at 0.1 m and 0.2 m is greater than that at the side.At the same time,the side of the building structure is more prone to liquefaction than the soil directly below it.展开更多
Structures modelled with flexible-base assumptions,incorporating soil effects,generally exhibit longer natural periods and higher damping compared to fixed-base models that exclude soil-structure interaction(SSI).Howe...Structures modelled with flexible-base assumptions,incorporating soil effects,generally exhibit longer natural periods and higher damping compared to fixed-base models that exclude soil-structure interaction(SSI).However,the beneficial or detrimental nature of SSI remains contentious in current earthquake damage analyses and research findings.This study introduces a numerical modelling technique,validated by experimental shaking table tests,to examine the effects of SSI on high-rise buildings.The study considers various substructure parameters,including foundation types,soil types,and bedrock depths.Both advantageous and adverse impacts of SSI are identified and analysed.Numerical simulations reveal that increased subsoil stiffness significantly amplifies the base shear of structures compared to bedrock depth effects.Additionally,increased foundation rocking results in higher inter-storey drifts and reduced base shear.Overall,SSI tends to amplify inter-storey drifts,indicating detrimental effects.Specifically,the study found that the inclusion of SSI increased maximum inter-storey drifts by up to 38%,particularly in softer soils,while reducing base shear by up to 44%in structures with classical compensated foundations on D_(e)and E_(e)soil types.In contrast,piled foundation systems experienced an increase in base shear of up to 27%under the same conditions.Conversely,SSI has beneficial impacts on base shear for structures with classical compensated foundations on soil types of D_(e)and E_(e),as it reduces the base shear.For structures with piled foundations and those with classical compensated foundations on C_(e)soil,SSI effects are detrimental.C_(e),D_(e),and E_(e)soils correspond to geotechnical classifications per AS1170,representing stiff,medium,and soft soils respectively.The study also presents minimum base shear ratios considering SSI reduction effects for various foundation types.展开更多
The biocemented coral sand pile composite foundation represents an innovative foundation improvement technology,utilizing Microbially Induced Carbonate Precipitation(MICP)to consolidate a specific volume of coral sand...The biocemented coral sand pile composite foundation represents an innovative foundation improvement technology,utilizing Microbially Induced Carbonate Precipitation(MICP)to consolidate a specific volume of coral sand within the foundation into piles with defined strength,thereby enabling them to collaboratively bear external loads with the surrounding unconsolidated coral sand.In this study,a series of shaking table model tests were conducted to explore the dynamic response of the biocemented coral sand pile composite foundation under varying seismic wave types and peak accelerations.The surface macroscopic phenomena,excess pore water pressure ratio,acceleration response,and vertical settlement were measured and analysed in detail.Test results show that seismic wave types play a decisive role in the macroscopic surface phenomena and the response of the excess pore water pressure ratio.The cumulative settlement of the upper structure under the action of Taft waves was about 1.5 times that of El Centro waves and Kobe waves.The most pronounced liquefaction phenomena were recorded under the Taft wave,followed by the El Centro wave,and subsequently the Kobe wave.An observed positive correlation was established between the liquefaction phenomenon and the Aristotelian in-tensity of the seismic waves.However,variations in seismic wave types exerted minimal influence on the ac-celeration amplification factor of the coral sand foundation.Analysis of the acceleration amplification factor revealed a triphasic pattern-initially increasing,subsequently decreasing,and finally increasing again-as burial depth increased,in relation to the peak value of the input acceleration.This study confirms that the biocemented coral sand pile composite foundation can effectively enhance the liquefaction resistance of coral sand foundations..展开更多
Bedding parallel stepped rock slopes exist widely in nature and are used in slope engineering.They are characterized by complex topography and geological structure and are vulnerable to shattering under strong earthqu...Bedding parallel stepped rock slopes exist widely in nature and are used in slope engineering.They are characterized by complex topography and geological structure and are vulnerable to shattering under strong earthquakes.However,no previous studies have assessed the mechanisms underlying seismic failure in rock slopes.In this study,large-scale shaking table tests and numerical simulations were conducted to delineate the seismic failure mechanism in terms of acceleration,displacement,and earth pressure responses combined with shattering failure phenomena.The results reveal that acceleration response mutations usually occur within weak interlayers owing to their inferior performance,and these mutations may transform into potential sliding surfaces,thereby intensifying the nonlinear seismic response characteristics.Cumulative permanent displacements at the internal corners of the berms can induce quasi-rigid displacements at the external corners,leading to greater permanent displacements at the internal corners.Therefore,the internal corners are identified as the most susceptible parts of the slope.In addition,the concept of baseline offset was utilized to explain the mechanism of earth pressure responses,and the result indicates that residual earth pressures at the internal corners play a dominant role in causing deformation or shattering damage.Four evolutionary deformation phases characterize the processes of seismic responses and shattering failure of the bedding parallel stepped rock slope,i.e.the formation of tensile cracks at the internal corners of the berm,expansion of tensile cracks and bedding surface dislocation,development of vertical tensile cracks at the rear edge,and rock mass slipping leading to slope instability.Overall,this study provides a scientific basis for the seismic design of engineering slopes and offers valuable insights for further studies on preventing seismic disasters in bedding parallel stepped rock slopes.展开更多
Actuator dynamics introduce a synchronization disparity between commanded displacements transmitted to the actuator and the actual displacements generated by the actuator,thereby affecting its precision and potentiall...Actuator dynamics introduce a synchronization disparity between commanded displacements transmitted to the actuator and the actual displacements generated by the actuator,thereby affecting its precision and potentially leading to instability in real-time hybrid simulation(RTHS).This study aims to elucidate the relationship between calculated and measured displacements by analyzing their magnitude and phase in the frequency domain via transformations.The physical implications of these relationships are explored in the context of frequency domain evaluation indices(FEI),the transfer function of actuator dynamics,and delay compensation.Formulations for achieving perfect compensation of actuator dynamics are developed,and an enhanced compensation approach,termed improved windowed frequency domain evaluation index-based compensation(IWFEI),is introduced.The efficacy of IWFEI is assessed using a RTHS benchmark model,with perturbed simulations conducted to validate its robustness.Uncertainties inherent in actuator dynamics are represented as random variables in these simulations.Comparative analysis of the mean values and variances of evaluation criteria demonstrates that IWFEI enables more accurate and robust compensation.Furthermore,strong correlations observed among criteria in the time and frequency domains underscore the effectiveness of the proposed frequency domain-based compensation method in mitigating amplitude errors and phase delays in RTHS.展开更多
Transmission tower-line systems(TTLSs)play a crucial role in the long-distance transmission of electrical energy,often necessitating their crossing through active fault areas.However,previous studies have given limite...Transmission tower-line systems(TTLSs)play a crucial role in the long-distance transmission of electrical energy,often necessitating their crossing through active fault areas.However,previous studies have given limited attention to the seismic performance of fault-crossing transmission TTLSs,particularly in terms of considering the impact of permanent ground motion displacements(PGMDs).This study attempts to address this concern by evaluating the seismic performance of TTLSs exposed to fault earthquakes.Three strike-slip ground motions are carefully selected,and the corresponding PGMDs are accurately replicated through baseline adjustment.A meticulously designed and fabricated reduced-scale experimental model of a TTLS is then employed to investigate the influence of the fault crossing location(FCL)on its seismic performance.The shake table tests conducted unequivocally demonstrate that PGMDs significantly amplify the seismic responses of the TTLS and identify the most unfavorable FCL.Furthermore,a finite element model(FEM)is developed and its accuracy is validated by comparing it with the experimental results.Parametric analyses are conducted to explore the effects of fault crossing angles(FCAs)and PGMD amplitudes on the seismic performances of TTLSs.This study is expected to contribute valuable insights for the seismic design and performance analysis of TTLSs crossing fault areas.展开更多
The relative stiffness between underground structures and surrounding soil may significantly influence the dynamic response of such structures.In this study,two underground pipelines were fabricated using rubber joint...The relative stiffness between underground structures and surrounding soil may significantly influence the dynamic response of such structures.In this study,two underground pipelines were fabricated using rubber joints with varying stiffness,and the corresponding dynamic response was evaluated.Model soils were prepared based on similarity ratios.Next,reduced-scale shaking table tests were conducted to investigate the impact of circular underground structures with varying stiffness joints on the amplification of ground acceleration,dynamic response,and deformation patterns of the underground pipelines.The comparative analysis showed that structures with lower stiffness exert less constraint on the surrounding soil,resulting in a higher amplification factor of ground acceleration.The seismic response of less stiff structures is generally 1.1 to 1.3 times the response of the stiffer structures.Therefore,the seismic response of the variable stiffness pipeline exhibits pronounced characteristics.Rubber joints effectively reduce the seismic response of underground structures,demonstrating favorable isolation effects.Consequently,relative stiffness plays a crucial role in the seismic design of underground structures,and the use of rubber materials in underground structures is advantageous.展开更多
In this study, shaking table tests were performed to investigate the dynamic characteristics of a mold transformer. Based on the test results, rotary friction dampers were developed to mitigate the excessive lateral d...In this study, shaking table tests were performed to investigate the dynamic characteristics of a mold transformer. Based on the test results, rotary friction dampers were developed to mitigate the excessive lateral displacement that occurred along the direction of the weak stiffness axis of the mold transformer. In addition, shaking table tests were performed by attaching friction dampers to both sides of the mold transformer. Based on the shaking table test results, the natural frequency, mode vector, and damping ratio of the mold transformer were derived using the transfer function and half-power bandwidth. The test results indicated that the use of friction dampers can decrease the displacement and acceleration response of the mold transformer. Finally, dynamic structural models were established considering the component connectivity and mass distribution of the mold transformer. In addition, a numerical strategy was proposed to calibrate the stiffness coefficients of the mold transformer, thereby facilitating the relationship between generalized mass and stiffness. The results indicated that the analytical model based on the calibration strategy of stiffness coefficients can reasonably simulate the dynamic behavior of the mold transformer using friction dampers with regard to transfer function, displacement, and acceleration response.展开更多
In this study,the design and development of a sensor made of low-cost parts to monitor inclination and acceleration are presented.Αmicro electro-mechanical systems,micro electro mechanical systems,sensor was housed i...In this study,the design and development of a sensor made of low-cost parts to monitor inclination and acceleration are presented.Αmicro electro-mechanical systems,micro electro mechanical systems,sensor was housed in a robust enclosure and interfaced with a Raspberry Pi microcomputer with Internet connectivity into a proposed tilt and acceleration monitoring node.Online capabilities accessible by mobile phone such as real-time graph,early warning notification,and database logging were implemented using Python programming.The sensor response was calibrated for inherent bias and errors,and then tested thoroughly in the laboratory under static and dynamic loading conditions beside high-quality transducers.Satisfactory accuracy was achieved in real time using the Complementary Filter method,and it was further improved in LabVIEW using Kalman Filters with parameter tuning.A sensor interface with LabVIEW and a 600 MHz CPU microcontroller allowed real-time implementation of highspeed embedded filters,further optimizing sensor results.Kalman and embedded filtering results show agreement for the sensor,followed closely by the lowcomplexity complementary filter applied in real time.The sensor's dynamic response was also verified by shaking table tests,simulating past recorded seismic excitations or artificial vibrations,indicating negligible effect of external acceleration on measured tilt;sensor measurements were benchmarked using highquality tilt and acceleration measuring transducers.A preliminary field evaluation shows robustness of the sensor to harsh weather conditions.展开更多
Shaking table tests are widely used to evaluate seismic effects on railway structures,but accurately measuring rail displacement remains a significant challenge owing to the nonlinear characteristics of large displace...Shaking table tests are widely used to evaluate seismic effects on railway structures,but accurately measuring rail displacement remains a significant challenge owing to the nonlinear characteristics of large displacements,ambient noise interference,and limitations in displacement meter installation.In this paper,a novel method that integrates the Kanade-Lucas-Tomasi(KLT)feature tracker with an extended Kalman filter(EKF)is presented for measuring rail displacement during shaking table tests.The method employs KLT feature tracker and a random sample consensus algorithm to extract and track key feature points,while EKF optimally estimates dynamic states by accounting for system noise and observation errors.Shaking table test results demonstrate that the proposed method achieves an acceleration root mean square error of 0.300 m/s^(2)and a correlation with accelerometer data exceeding 99.7%,significantly outper-forming the original KLT approach.This innovative method provides a more efficient and reliable solution for measuring rail displacement under large nonlinear vibrations.展开更多
As an important part of nonstructural components,the seismic response of indoor water supply pipes deserves much attention.This paper presents shaking table test research on water supply pipes installed in a full-scal...As an important part of nonstructural components,the seismic response of indoor water supply pipes deserves much attention.This paper presents shaking table test research on water supply pipes installed in a full-scale reinforced concrete(RC)frame structure.Different material pipes and different methods for penetrating the reinforced concrete floors are combined to evaluate the difference in seismic performance.Floor response spectra and pipe acceleration amplification factors based on test data are discussed and compared with code provisions.A seismic fragility study of displacement demand is conducted based on numerical simulation.The acceleration response and displacement response of different combinations are compared.The results show that the combination of different pipe materials and different passing-through methods can cause obvious differences in the seismic response of indoor riser pipes.展开更多
Seismic isolation effectively reduces seismic demands on building structures by isolating the superstructure from ground vibrations during earthquakes.However,isolation strategies give less attention to acceleration-s...Seismic isolation effectively reduces seismic demands on building structures by isolating the superstructure from ground vibrations during earthquakes.However,isolation strategies give less attention to acceleration-sensitive systems or equipment.Meanwhile,as the isolation layer’s displacement grows,the stiffness and frequency of traditional rolling and sliding isolation bearings increases,potentially causing self-centering and resonance concerns.As a result,a new conical pendulum bearing has been selected for acceleration-sensitive equipment to increase self-centering capacity,and additional viscous dampers are incorporated to enhance system damping.Moreover,the theoretical formula for conical pendulum bearings is supplied to analyze the device’s dynamic parameters,and shake table experiments are used to determine the proposed device’s isolation efficiency under various conditions.According to the test results,the newly proposed devices have remarkable isolation performance in terms of minimizing both acceleration and displacement responses.Finally,a numerical model of the isolation system is provided for further research,and the accuracy is demonstrated by the aforementioned experiments.展开更多
基金supported by the Natural Science Foundation of China(Grant Nos.U21A2023 and 32072621)the earmarked fund for CARS-19 and the Youth Science and Technology Talents Support Program(2020)by Anhui Association for Science and Technology(Grant No.RCTJ202010).
文摘Tea flavor is a comprehensive representation of its aroma and other characteristics.The formation of volatile odor compounds during tea processing depends on a variety of enzymatic and non-enzymatic activities.(Z)-3-hexenol is considered the primary source of the green odor and is also the most important component in tea aroma,significantly affecting the overall aroma.However,the biosynthesis and accumulation of(Z)-3-hexenol during tea processing have not been fully analyzed.In this study,we found that withering treatment at different times and withering plus shaking treatment at different degrees promoted the accumulation of important volatile components of green tea odor,especially(Z)-3-hexenol by GC-MS.The RNA-seq and qRT-PCR results showed that withering and withering plus shaking treatments enhanced the expression of(Z)-3-hexenol-related genes in tea leaves,including synthetic pathway 1 genes(CsLOX3,CsHPL1,CsADH4,and CsAHD1),synthetic pathway 2 genes(CsGLU),and synthetic pathway 3 genes(CsCXEs).Correlation analysis of the key odorants and important genes in the three synthetic pathways revealed that some CsCXEs were positively correlated with green odor compounds.The in vitro enzyme activity results showed that rCsCXE3(GWHTASIV011658),and rCsCXE6(GWHTASIV031480)exhibited hydrolytic activity against three tea acetate compounds[hexyl acetate,(E)-2-hexyl acetate,and(Z)-3-hexyl acetate],resulting in the production of corresponding alcohol compounds.In summary,withering and shaking treatment during tea processing promoted the expression of CsCXE3 and CsCXE6,thereby enhancing the production of hexenol compounds.These compounds play a crucial role in increasing the green odor of tea.
基金fellowship received from the Department of Science and Technology(DST)under a unique scheme,“Innovation in Science Pursuit for Inspired Research(INSPIRE),”under the file number 20190000871,during the present work。
文摘The present study investigates the influence of embedment depth of isolated footing supporting moment-resisting frame buildings through scaled-down tests.These experiments utilize scaled models representing different building aspect ratios and footing embedment depths.All the model tests are subjected to scaled-down input ground motions of different intensities and magnitudes.These model tests are performed in laminar shear containers through shake table testing.The results obtained for different cases of soil-foundation-structure systems and fixed-base conditions are expressed in terms of natural frequency,peak spectral acceleration,frequency response,lateral deformation,inter-storey drifts,and rocking of the foundation.The analysis reveals that the natural frequency of the coupled system on isolated footings diminishes by 27.52%–58.21%relative to fixed-base conditions,highlighting the significance of accounting for soil-foundation-structure interaction effects.Moreover,a notable increase of 52.97%in the natural frequency of the coupled system is observed as the embedment depth of the footing increases from 0.75 to 6.Additionally,the study demonstrates that the inter-storey drift of the 5-storey building remains well within acceptable limits under dense soil conditions.Consequently,within the parameter range explored in this research,the study concludes that soil-foundation-structure interaction effects are insignificant for low-rise buildings(H≤15 m)supported on isolated footings during seismic events.
基金the support from the Outstanding Youth Foundation of Shandong Province(ZR2021YQ31)the National Natural Science Foundation of China(42277135)+5 种基金National Foreign Experts Individual Program(Category Y)(Grant No.Y20240084)the National Natural Science Foundation of China Joint Fund Key Project(U2006225)Special Fund for Taishan Scholar Projectthe Youth Project of Open Funding from Engineering Research Center of Concrete Technology under Marine Environment,Ministry of Education(Grant No.TMduracon202217)the funding from Key Laboratory of Ministry of Education for Coastal Disaster and Protection,Hohai University(Grant No.202206)Shandong Provincial Overseas High-Level Talent Workstation,China。
文摘Seismic-induced landslides critically threaten infrastructure and human safety,especially in sandy slopes where conventional stabilization methods often fail under dynamic loading.This study evaluates circular open-ended anti-slide pipe piles embedded in a two-layer sandy slope with differing geotechnical properties.Ten physical models,including five freefield and five pile-reinforced slopes,were tested on a shaking table.Key seismic responses—acceleration,soil displacement,and bending moments—were monitored using accelerometers,strain gauges,and Digital Image Correlation(DIC).Complementary numerical simulations using Abaqus with a Mohr–Coulomb model validated experimental results.Soil displacement in free-field models under 0.25g shaking was about 3.5 times greater than in reinforced slopes.Bending moments increased with seismic intensity,peaking at depths around five times the pile diameter.Limitations including simplified two-layer soil representation,idealized seismic inputs,and boundary effects inherent to laboratory models restrict direct field application but enable controlled analysis.By combining physical experiments with numerical modeling,the study provides a robust and validated framework for seismic slope stabilization.This integrated approach enhances understanding of soil–pile interaction under seismic loads and offers targeted insights for developing safer and more reliable geotechnical design strategies in earthquake-prone areas.
基金supported by the National Natural Science Foundation of China(Grant nos.12075145 and 12211540002)the Science and Technology Commission of Shanghai Municipal(Grant no.2019SHZDZX01-ZX04)。
文摘This article primarily establishes a two-soliton system and employs the Lewis-Riesenfeld invariant inverse control method to achieve shortcuts to adiabaticity(STA)technology.We study an atomic soliton Josephson junctions(SJJs)device and subsequently compare and analyze it with atomic bosonic Josephson junctions.Moreover,we use higher-order expressions of the auxiliary equations to optimize the results and weaken the detrimental effect of the sloshing amplitude.We find that in the adiabatic shortcut evolution of two systems with time-containing tunnelling rates,the SJJs system is more robust over a rather short time evolution.In comparison with linear ramping,the STA technique is easier to achieve with the precise modulation of the quantum state in the SJJs system.
基金funding support from the National Nature Science Foundation of China(Grant No.41931296)the Open Research Project of Sichuan Provincial Key Laboratory for Major Hazard Source Monitoring and Control(Grant No.KFKT2023-4)the 57#Project(Grant No.JH2024015).
文摘Weak interlayers play a crucial role in the seismic performance of bedding slopes;however,the effects of structural surface development within these layers remain underexplored.This study presents two scaled models of bedding slopes,each with different weak interlayers:one with a homogeneous weak layer and another with discontinuous interfaces.Shaking table tests were conducted to compare their seismic performance.The results show that the peak ground acceleration(PGA)values above the weak interlayer in model A were significantly higher than those in model B,with the differences increasing as the input wave amplitude increased.The peak earth pressure(PEP)values at the tensile failure boundary at the rear edge of model A were also higher,whereas those within the weak layer at the toe of model A were lower than those in model B.Deformation analysis revealed that the maximum principal strain in model A initially appeared at the upper part of the tensile failure boundary,while the maximum shear strain was concentrated near the rear edge within the weak layer.In contrast,model B exhibited the opposite strain distribution.These findings provide insight into the impact of weak interlayers on the dynamic response and deformation of bedding slopes,highlighting the importance of considering this factor in seismic landslide investigations and failure mode predictions.
基金funded by the National Natural Science Foundation of China(Grant No.42377195)。
文摘A fault is a geological structure characterized by significant displacement of rock masses along a fault plane within the Earth's crust.The Yunnan Tabaiyi Tunnel intersects multiple fault zones,making tunnel construction in fault-prone areas particularly vulnerable to the effects of fault activity due to the complexities of the surrounding geological environment.To investigate the dynamic response characteristics of tunnel structures under varying surrounding rock conditions,a three-dimensional large-scale shaking table physical model test was conducted.This study also aimed to explore the damage mechanisms associated with the Tabaiyi Tunnel under seismic loading.The results demonstrate that poor quality surrounding rock enhances the seismic response of the tunnel.This effect is primarily attributed to the distribution characteristics of acceleration,dynamic strain,and dynamic soil pressure.A comparison between unidirectional and multi-directional(including vertical)seismic motions reveals that vertical seismic motion has a more significant impact on specific tunnel locations.Specifically,the maximum tensile stress is observed at the arch shoulder,with values ranging from 60 to 100 k Pa.Moreover,NPR(Non-Prestressed Reinforced)anchor cables exhibit a substantial constant resistance effect under low-amplitude seismic waves.However,when the input earthquake amplitude reaches 0.8g,local sliding occurs at the arch shoulder region of the NPR anchor cable.These findings underscore the importance of focusing on seismic mitigation measures in fault zones and reinforcing critical areas,such as the arch shoulders,in practical engineering applications.
基金National Natural Science Foundation of China under Grant No.U21A20164National Science Fund for Distinguished Young Scholars of China under Grant No.51825904。
文摘Seismic-induced liquefaction of sandy soils can fail foundations in the vicinity of buildings.To investigate the effect of a non-free field subsurface seismic history on the ability of saturated sandy soils to resist liquefaction,four shaking events with different accelerations were input to the sandy soils in the non-free-field.The results of the study revealed that:(1)Shallow soils that are not free-field undergo acceleration amplification effects after being subjected to seismic loading.(2)Building overburden pressure reduces the sensitivity of the shallow soils directly below in small and moderate earthquakes,which are more prone to rearranging and forming unstable structures under strong seismic effects.The excess pore pressure response on the load side resembles that of a free site,with the depth range of the liquefaction strength of soils affected by the seismic history,increasing progressively as input seismic intensity increases.(3)After experiencing earthquakes of different intensities,the excess pore pressure directly below the building overburden pressure at 0.1 m and 0.2 m is greater than that at the side.At the same time,the side of the building structure is more prone to liquefaction than the soil directly below it.
文摘Structures modelled with flexible-base assumptions,incorporating soil effects,generally exhibit longer natural periods and higher damping compared to fixed-base models that exclude soil-structure interaction(SSI).However,the beneficial or detrimental nature of SSI remains contentious in current earthquake damage analyses and research findings.This study introduces a numerical modelling technique,validated by experimental shaking table tests,to examine the effects of SSI on high-rise buildings.The study considers various substructure parameters,including foundation types,soil types,and bedrock depths.Both advantageous and adverse impacts of SSI are identified and analysed.Numerical simulations reveal that increased subsoil stiffness significantly amplifies the base shear of structures compared to bedrock depth effects.Additionally,increased foundation rocking results in higher inter-storey drifts and reduced base shear.Overall,SSI tends to amplify inter-storey drifts,indicating detrimental effects.Specifically,the study found that the inclusion of SSI increased maximum inter-storey drifts by up to 38%,particularly in softer soils,while reducing base shear by up to 44%in structures with classical compensated foundations on D_(e)and E_(e)soil types.In contrast,piled foundation systems experienced an increase in base shear of up to 27%under the same conditions.Conversely,SSI has beneficial impacts on base shear for structures with classical compensated foundations on soil types of D_(e)and E_(e),as it reduces the base shear.For structures with piled foundations and those with classical compensated foundations on C_(e)soil,SSI effects are detrimental.C_(e),D_(e),and E_(e)soils correspond to geotechnical classifications per AS1170,representing stiff,medium,and soft soils respectively.The study also presents minimum base shear ratios considering SSI reduction effects for various foundation types.
基金supported by the National Natural Science Foundation of China(No.51978103,No.52308340,No.52408355)the Postdoctoral Fellowship Program of CPSF(No.BX20240450)Chongqing Talent Innovation and Entrepreneurship Demonstration Team Project(No.cstc2024ycjh-bgzxm0012).
文摘The biocemented coral sand pile composite foundation represents an innovative foundation improvement technology,utilizing Microbially Induced Carbonate Precipitation(MICP)to consolidate a specific volume of coral sand within the foundation into piles with defined strength,thereby enabling them to collaboratively bear external loads with the surrounding unconsolidated coral sand.In this study,a series of shaking table model tests were conducted to explore the dynamic response of the biocemented coral sand pile composite foundation under varying seismic wave types and peak accelerations.The surface macroscopic phenomena,excess pore water pressure ratio,acceleration response,and vertical settlement were measured and analysed in detail.Test results show that seismic wave types play a decisive role in the macroscopic surface phenomena and the response of the excess pore water pressure ratio.The cumulative settlement of the upper structure under the action of Taft waves was about 1.5 times that of El Centro waves and Kobe waves.The most pronounced liquefaction phenomena were recorded under the Taft wave,followed by the El Centro wave,and subsequently the Kobe wave.An observed positive correlation was established between the liquefaction phenomenon and the Aristotelian in-tensity of the seismic waves.However,variations in seismic wave types exerted minimal influence on the ac-celeration amplification factor of the coral sand foundation.Analysis of the acceleration amplification factor revealed a triphasic pattern-initially increasing,subsequently decreasing,and finally increasing again-as burial depth increased,in relation to the peak value of the input acceleration.This study confirms that the biocemented coral sand pile composite foundation can effectively enhance the liquefaction resistance of coral sand foundations..
基金supported by the National Natural Science Foundation of China (Grant No.52108361)the Sichuan Science and Technology Program of China (Grant No.2023YFS0436)the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project (Grant No.SKLGP2022Z015).
文摘Bedding parallel stepped rock slopes exist widely in nature and are used in slope engineering.They are characterized by complex topography and geological structure and are vulnerable to shattering under strong earthquakes.However,no previous studies have assessed the mechanisms underlying seismic failure in rock slopes.In this study,large-scale shaking table tests and numerical simulations were conducted to delineate the seismic failure mechanism in terms of acceleration,displacement,and earth pressure responses combined with shattering failure phenomena.The results reveal that acceleration response mutations usually occur within weak interlayers owing to their inferior performance,and these mutations may transform into potential sliding surfaces,thereby intensifying the nonlinear seismic response characteristics.Cumulative permanent displacements at the internal corners of the berms can induce quasi-rigid displacements at the external corners,leading to greater permanent displacements at the internal corners.Therefore,the internal corners are identified as the most susceptible parts of the slope.In addition,the concept of baseline offset was utilized to explain the mechanism of earth pressure responses,and the result indicates that residual earth pressures at the internal corners play a dominant role in causing deformation or shattering damage.Four evolutionary deformation phases characterize the processes of seismic responses and shattering failure of the bedding parallel stepped rock slope,i.e.the formation of tensile cracks at the internal corners of the berm,expansion of tensile cracks and bedding surface dislocation,development of vertical tensile cracks at the rear edge,and rock mass slipping leading to slope instability.Overall,this study provides a scientific basis for the seismic design of engineering slopes and offers valuable insights for further studies on preventing seismic disasters in bedding parallel stepped rock slopes.
基金Ministry of Science and Technology of China under Grant No.2023YFC3804300National Science Foundation of China under Grant No.52178114。
文摘Actuator dynamics introduce a synchronization disparity between commanded displacements transmitted to the actuator and the actual displacements generated by the actuator,thereby affecting its precision and potentially leading to instability in real-time hybrid simulation(RTHS).This study aims to elucidate the relationship between calculated and measured displacements by analyzing their magnitude and phase in the frequency domain via transformations.The physical implications of these relationships are explored in the context of frequency domain evaluation indices(FEI),the transfer function of actuator dynamics,and delay compensation.Formulations for achieving perfect compensation of actuator dynamics are developed,and an enhanced compensation approach,termed improved windowed frequency domain evaluation index-based compensation(IWFEI),is introduced.The efficacy of IWFEI is assessed using a RTHS benchmark model,with perturbed simulations conducted to validate its robustness.Uncertainties inherent in actuator dynamics are represented as random variables in these simulations.Comparative analysis of the mean values and variances of evaluation criteria demonstrates that IWFEI enables more accurate and robust compensation.Furthermore,strong correlations observed among criteria in the time and frequency domains underscore the effectiveness of the proposed frequency domain-based compensation method in mitigating amplitude errors and phase delays in RTHS.
基金Shandong Provincial Natural Science Foundation for Distinguished Young Scholars under Grant No.ZR2022JQ27the Taishan Scholars Program
文摘Transmission tower-line systems(TTLSs)play a crucial role in the long-distance transmission of electrical energy,often necessitating their crossing through active fault areas.However,previous studies have given limited attention to the seismic performance of fault-crossing transmission TTLSs,particularly in terms of considering the impact of permanent ground motion displacements(PGMDs).This study attempts to address this concern by evaluating the seismic performance of TTLSs exposed to fault earthquakes.Three strike-slip ground motions are carefully selected,and the corresponding PGMDs are accurately replicated through baseline adjustment.A meticulously designed and fabricated reduced-scale experimental model of a TTLS is then employed to investigate the influence of the fault crossing location(FCL)on its seismic performance.The shake table tests conducted unequivocally demonstrate that PGMDs significantly amplify the seismic responses of the TTLS and identify the most unfavorable FCL.Furthermore,a finite element model(FEM)is developed and its accuracy is validated by comparing it with the experimental results.Parametric analyses are conducted to explore the effects of fault crossing angles(FCAs)and PGMD amplitudes on the seismic performances of TTLSs.This study is expected to contribute valuable insights for the seismic design and performance analysis of TTLSs crossing fault areas.
基金Key International(Regional)Joint Research Project under Grant No.52020105002National Natural Science Foundation of China under Grant No.51991393。
文摘The relative stiffness between underground structures and surrounding soil may significantly influence the dynamic response of such structures.In this study,two underground pipelines were fabricated using rubber joints with varying stiffness,and the corresponding dynamic response was evaluated.Model soils were prepared based on similarity ratios.Next,reduced-scale shaking table tests were conducted to investigate the impact of circular underground structures with varying stiffness joints on the amplification of ground acceleration,dynamic response,and deformation patterns of the underground pipelines.The comparative analysis showed that structures with lower stiffness exert less constraint on the surrounding soil,resulting in a higher amplification factor of ground acceleration.The seismic response of less stiff structures is generally 1.1 to 1.3 times the response of the stiffer structures.Therefore,the seismic response of the variable stiffness pipeline exhibits pronounced characteristics.Rubber joints effectively reduce the seismic response of underground structures,demonstrating favorable isolation effects.Consequently,relative stiffness plays a crucial role in the seismic design of underground structures,and the use of rubber materials in underground structures is advantageous.
基金Basic Science Research Program of the National Research Foundation of Korea under Grant Nos.NRF-2020R1A6A1A03044977 and NRF2022R1A2C2004351。
文摘In this study, shaking table tests were performed to investigate the dynamic characteristics of a mold transformer. Based on the test results, rotary friction dampers were developed to mitigate the excessive lateral displacement that occurred along the direction of the weak stiffness axis of the mold transformer. In addition, shaking table tests were performed by attaching friction dampers to both sides of the mold transformer. Based on the shaking table test results, the natural frequency, mode vector, and damping ratio of the mold transformer were derived using the transfer function and half-power bandwidth. The test results indicated that the use of friction dampers can decrease the displacement and acceleration response of the mold transformer. Finally, dynamic structural models were established considering the component connectivity and mass distribution of the mold transformer. In addition, a numerical strategy was proposed to calibrate the stiffness coefficients of the mold transformer, thereby facilitating the relationship between generalized mass and stiffness. The results indicated that the analytical model based on the calibration strategy of stiffness coefficients can reasonably simulate the dynamic behavior of the mold transformer using friction dampers with regard to transfer function, displacement, and acceleration response.
基金Research Committee,National Technical University of Athens。
文摘In this study,the design and development of a sensor made of low-cost parts to monitor inclination and acceleration are presented.Αmicro electro-mechanical systems,micro electro mechanical systems,sensor was housed in a robust enclosure and interfaced with a Raspberry Pi microcomputer with Internet connectivity into a proposed tilt and acceleration monitoring node.Online capabilities accessible by mobile phone such as real-time graph,early warning notification,and database logging were implemented using Python programming.The sensor response was calibrated for inherent bias and errors,and then tested thoroughly in the laboratory under static and dynamic loading conditions beside high-quality transducers.Satisfactory accuracy was achieved in real time using the Complementary Filter method,and it was further improved in LabVIEW using Kalman Filters with parameter tuning.A sensor interface with LabVIEW and a 600 MHz CPU microcontroller allowed real-time implementation of highspeed embedded filters,further optimizing sensor results.Kalman and embedded filtering results show agreement for the sensor,followed closely by the lowcomplexity complementary filter applied in real time.The sensor's dynamic response was also verified by shaking table tests,simulating past recorded seismic excitations or artificial vibrations,indicating negligible effect of external acceleration on measured tilt;sensor measurements were benchmarked using highquality tilt and acceleration measuring transducers.A preliminary field evaluation shows robustness of the sensor to harsh weather conditions.
基金The National Key Research and Development Program of China(No.2021YFB2600600,2021YFB2600601)the National Natural Science Foundation of China(No.52408456)+2 种基金China Postdoctoral Science Foundation(No.2022M720533)College Students’Innovative Entrepreneurial Training Plan Program(No.202410710009)Key Research and Development Program of Shaanxi,China(No.2024SF-YBXM-659).
文摘Shaking table tests are widely used to evaluate seismic effects on railway structures,but accurately measuring rail displacement remains a significant challenge owing to the nonlinear characteristics of large displacements,ambient noise interference,and limitations in displacement meter installation.In this paper,a novel method that integrates the Kanade-Lucas-Tomasi(KLT)feature tracker with an extended Kalman filter(EKF)is presented for measuring rail displacement during shaking table tests.The method employs KLT feature tracker and a random sample consensus algorithm to extract and track key feature points,while EKF optimally estimates dynamic states by accounting for system noise and observation errors.Shaking table test results demonstrate that the proposed method achieves an acceleration root mean square error of 0.300 m/s^(2)and a correlation with accelerometer data exceeding 99.7%,significantly outper-forming the original KLT approach.This innovative method provides a more efficient and reliable solution for measuring rail displacement under large nonlinear vibrations.
基金Scientific Research Fund of Institute of Engineering Mechanics,China Earthquake Administration under Grant Nos.2021EEEVL0204 and 2018A02。
文摘As an important part of nonstructural components,the seismic response of indoor water supply pipes deserves much attention.This paper presents shaking table test research on water supply pipes installed in a full-scale reinforced concrete(RC)frame structure.Different material pipes and different methods for penetrating the reinforced concrete floors are combined to evaluate the difference in seismic performance.Floor response spectra and pipe acceleration amplification factors based on test data are discussed and compared with code provisions.A seismic fragility study of displacement demand is conducted based on numerical simulation.The acceleration response and displacement response of different combinations are compared.The results show that the combination of different pipe materials and different passing-through methods can cause obvious differences in the seismic response of indoor riser pipes.
基金Scientific Research Fund of Institute of Engineering Mechanics,CEA under Grant No.2019A03Scientific Research Fund of Institute of Engineering Mechanics,CEA under Grant No.2021D12National Key R&D Program of China under No.2018YFC1504404。
文摘Seismic isolation effectively reduces seismic demands on building structures by isolating the superstructure from ground vibrations during earthquakes.However,isolation strategies give less attention to acceleration-sensitive systems or equipment.Meanwhile,as the isolation layer’s displacement grows,the stiffness and frequency of traditional rolling and sliding isolation bearings increases,potentially causing self-centering and resonance concerns.As a result,a new conical pendulum bearing has been selected for acceleration-sensitive equipment to increase self-centering capacity,and additional viscous dampers are incorporated to enhance system damping.Moreover,the theoretical formula for conical pendulum bearings is supplied to analyze the device’s dynamic parameters,and shake table experiments are used to determine the proposed device’s isolation efficiency under various conditions.According to the test results,the newly proposed devices have remarkable isolation performance in terms of minimizing both acceleration and displacement responses.Finally,a numerical model of the isolation system is provided for further research,and the accuracy is demonstrated by the aforementioned experiments.
