Accurate prediction of landslide displacement is crucial for effective early warning of landslide disasters.While most existing prediction methods focus on time-series forecasting for individual monitoring points,ther...Accurate prediction of landslide displacement is crucial for effective early warning of landslide disasters.While most existing prediction methods focus on time-series forecasting for individual monitoring points,there is limited research on the spatiotemporal characteristics of landslide deformation.This paper proposes a novel Multi-Relation Spatiotemporal Graph Residual Network with Multi-Level Feature Attention(MFA-MRSTGRN)that effectively improves the prediction performance of landslide displacement through spatiotemporal fusion.This model integrates internal seepage factors as data feature enhancements with external triggering factors,allowing for accurate capture of the complex spatiotemporal characteristics of landslide displacement and the construction of a multi-source heterogeneous dataset.The MFA-MRSTGRN model incorporates dynamic graph theory and four key modules:multilevel feature attention,temporal-residual decomposition,spatial multi-relational graph convolution,and spatiotemporal fusion prediction.This comprehensive approach enables the efficient analyses of multi-source heterogeneous datasets,facilitating adaptive exploration of the evolving multi-relational,multi-dimensional spatiotemporal complexities in landslides.When applying this model to predict the displacement of the Liangshuijing landslide,we demonstrate that the MFA-MRSTGRN model surpasses traditional models,such as random forest(RF),long short-term memory(LSTM),and spatial temporal graph convolutional networks(ST-GCN)models in terms of various evaluation metrics including mean absolute error(MAE=1.27 mm),root mean square error(RMSE=1.49 mm),mean absolute percentage error(MAPE=0.026),and R-squared(R^(2)=0.88).Furthermore,feature ablation experiments indicate that incorporating internal seepage factors improves the predictive performance of landslide displacement models.This research provides an advanced and reliable method for landslide displacement prediction.展开更多
An analytical method is developed to investigate the dynamic response of a pile subjected to harmonic vertical loading.The pile is modeled as a one-dimensional（1D）elastic rod.The elastic soil is divided into a homog...An analytical method is developed to investigate the dynamic response of a pile subjected to harmonic vertical loading.The pile is modeled as a one-dimensional（1D）elastic rod.The elastic soil is divided into a homogeneous half space underlying the base of pile and a series of infinitesimally thin layers along the vertical shaft of pile.The analytical solution for the soil-pile dynamic interaction problem is obtained by the method of Hankel transformation.The proposed solution is compared with the classical plane strain solution.Arithmetical examples are presented to demonstrate the sensitivity of the vertical impedance of the pile to relevant parameters.展开更多
In recent years,the development and construction of island reefs have been flourishing.Due to the remoteness of island reefs from the mainland,the scarcity of building materials,and the high transportation costs,it is...In recent years,the development and construction of island reefs have been flourishing.Due to the remoteness of island reefs from the mainland,the scarcity of building materials,and the high transportation costs,it is imperative to use local marine resources,and the potential value and status of coral mud on island reefs,which is formed by the remains of corals and other biological entities,is becoming increasingly prominent.Utilization and optimization of natural resources on island reefs have become a brand-new research direction and challenge.This article mainly focuses on the development of a new type of green engineering material,coral mud,for use in building surface layers.Thickness effects,PVA fiber(vinylon staple fiber)modification,and HPMC(Hydroxypropyl Methyl Cellulose)adhesive modification are taken into consideration.Through laboratory tests and image processing technology,fractal theory,and electron microscopy experiments,the macro-meso-microscopic multi-scale cracking rules of the coral mud surface layer and the optimization modification rules of PVA fibers and HPMC adhesives are revealed.The results demonstrate that the performance of the coral mud surface layer is superior to that of the kaolin surface layer,and the 10 mm thickness performs better than the 5 mm and 20 mm thicknesses.As the thickness of the coral mud surface layer increases,the contact between coral mud particles becomes denser,the scale of surface micro-cracks decreases,and the number of micro-pores decreases.PVA fibers can effectively inhibit the further development of macro and micro cracks and play a good bridging role.There is a bonding and adhesion relationship between coral mud and PVA fibers,and they have a good synergistic effect in inhibiting macro and mesoscopic cracks.With the increase in HPMC adhesive content,the number of micro-cracks and the scale of micro-cracks decrease accordingly,and the structure and performance of the coral mud surface layer are further improved.Overall,PVA fibers are more effective than HPMC adhesives in inhibiting the cracking of the coral mud surface layer.This provides valuable guidance for the development and application of coral mud in wall surface materials.展开更多
A series of small-scale 1g X-section cast-in-place concrete(XCC)pile-penetration model tests were conducted to study the effects of soil density and pile geometry on the lateral responses of an existing pile and the v...A series of small-scale 1g X-section cast-in-place concrete(XCC)pile-penetration model tests were conducted to study the effects of soil density and pile geometry on the lateral responses of an existing pile and the variations in surrounding soil stress.The results showed that the bending patterns of existing XCC piles varied with penetration depth.The lateral response of the existing pile was sensitive to the change in relative density and pile geometry.For example,the bending moment of the existing pile increased along with these parameters.The development of the radial stressσ′r/σ′v0 of the soil around an existing pile showed different trends at various depths during the penetration of the adjacent pile.Moreover,the change in radial stress during the penetration of the XCC pile did not exhibit the“h/R effect”that was observed in the free-field soil,due to the shielding effect of the existing piles.The peak value of radial stressσ′r_max/σ′v0 decreased exponentially as the radial distance r/R increased.The attenuation ofσ′r_max/σ′v0 with r/R in the loose sand was faster than in the medium-dense or dense sands.Theσ′r_max/σ′v0 at the same soil location increased with the cross-section geometry parameter.展开更多
The performance of geosynthetic-reinforced embankments under traffic moving loads is always a hotspot in the geotechnical engineering field.A three-dimensional(3D)model of a geosynthetic-reinforced embankment without ...The performance of geosynthetic-reinforced embankments under traffic moving loads is always a hotspot in the geotechnical engineering field.A three-dimensional(3D)model of a geosynthetic-reinforced embankment without drainage consolidation was established using the finite element software ABAQUS.In this model,the traffic loads were simulated by two moving loads of rectangular pattern,and their amplitude,range,and moving speed were realized by a Fortran subroutine.The embankment fill was simulated by an equivalent linear viscoelastic model,which can reflect its viscoelasticity.The geogrid was simulated by the truss element,and the geocell was simulated by the membrane element.Infinite elements were utilized to weaken the boundary effect caused by the model geometry at the boundaries.Validation of the established numerical model was conducted by comparing the predicted deformations in the cross-section of the geosynthetic-reinforced embankment with those from the existing literature.On this basis,the dynamic stress and strain distribution in the pavement structure layer of the geosynthetic-reinforced embankment under a moving load was also analyzed.Finally,a parametric study was conducted to examine the influences of the different types of reinforcement,overload,and the moving load velocity on the geosynthetic-reinforced embankment.展开更多
This paper presents a confidence ellipse-based method to evaluate the similarity of soil parametric data using the database from the site investigation reports.Then,the obtained similarity assessment results of parame...This paper presents a confidence ellipse-based method to evaluate the similarity of soil parametric data using the database from the site investigation reports.Then,the obtained similarity assessment results of parametric data are used to further estimate the site similarity via two proposed strategies,namely the mean and weighted mean approaches.The former referred to the average of parametric data similarity degrees,while the latter was the weighted average,and the weight was calculated using the coefficient of variation(COV)of each parameter.For illustration,the liquidity index(LI)dataset was firstly used to explore the performance of the presented method in the evaluation of parametric data similarity.Subsequently,the site similarity was assessed and the effects of numbers and weights of selected parameters for study were systematically studied.Lastly,the transformation models about the relationships between Cc and x as well as between Cc and e0 were constructed to illustrate the application of the similarity analysis in reduction of transformation uncertainty.Results show that the greatest site similarity degree is at about 0.76 in this study,and the maximum decrease of transformation uncertainty can reach up to 18%and 25.5%as union parametric data similarity degree increases.Moreover,the site similarity degree represents the whole similarity between two different sites,and the presented union parameter similarity degree maintains a good agreement with transformation uncertainty.展开更多
An analytical solution is developed in this paper to conduct the low-strain integrity testing for a pipe pile with multiple defects.The derived solution allows simulating the pipe pile as a three-dimensional model by ...An analytical solution is developed in this paper to conduct the low-strain integrity testing for a pipe pile with multiple defects.The derived solution allows simulating the pipe pile as a three-dimensional model by considering the wave propagation in the vertical,circumferential and radial directions.Analytical solutions of the pile are obtained by the Laplace transform and separation of variables.Accordingly,time-domain responses of the solution are deduced by the inverse Fourier transform numerically.The solution is validated against the published solutions for an intact pile and a pile with a single defect.Parametric studies are conducted to identify and characterize the velocity responses on the top of pipe piles with multiple defects.Numerical results suggest that the reflected waves generated by the deep defects are affected by the secondary reflections from the shallow defects.A new detecting method is proposed to decrease the influence of high-frequency interferences and to predict the defective depth,which suggests putting the receiver at the point of 90°along the circumferential direction.展开更多
In this study, a three-dimensional (3D) finite element modelling (FEM) analysis is carried out to investigate the effects of soil spatial variability on the response of retaining walls and an adjacent box culvert due ...In this study, a three-dimensional (3D) finite element modelling (FEM) analysis is carried out to investigate the effects of soil spatial variability on the response of retaining walls and an adjacent box culvert due to a braced excavation. The spatial variability of soil stiffness is modelled using a variogram and calibrated by high-quality experimental data. Multiple random field samples (RFSs) of soil stiffness are generated using geostatistical analysis and mapped onto a finite element mesh for stochastic analysis of excavation-induced structural responses by Monte Carlo simulation. It is found that the spatial variability of soil stiffness can be described by an exponential variogram, and the associated vertical correlation length is varied from 1.3 m to 1.6 m. It also reveals that the spatial variability of soil stiffness has a significant effect on the variations of retaining wall deflections and box culvert settlements. The ignorance of spatial variability in 3D FEM can result in an underestimation of lateral wall deflections and culvert settlements. Thus, the stochastic structural responses obtained from the 3D analysis could serve as an effective aid for probabilistic design and analysis of excavations.展开更多
Engineered cementitious composites(ECC)are highly ductile materials with excellent crack control capabilities,making them well-suited for structural applications requiring enhanced durability and resilience.In mountai...Engineered cementitious composites(ECC)are highly ductile materials with excellent crack control capabilities,making them well-suited for structural applications requiring enhanced durability and resilience.In mountainous engineering construction,stabilizing high-steep slopes presents a significant challenge,with sheet-pile walls commonly employed to improve seismic stability.To assess the effectiveness of ECC in such applications,this study conducted two comparative shaking table tests to investigate the seismic performance of high-steep slopes supported by ECC sheet-pile walls.The failure modes,acceleration responses,dynamic earth pressure responses,bending moments of anti-sliding piles,and lateral displacement responses of the ECC-supported slope were systematically analyzed and compared with those of slopes supported by traditional reinforced concrete(RC)sheet-pile walls.The test results indicate that ECC-supported slopes exhibited significantly better seismic performance than RC-supported slopes.ECC sheet-pile wall maintained structural integrity at higher seismic intensities(PGA=1.2g)compared with RC walls,which failed at PGA=1.0g.Under the same seismic loading,ECC-supported slopes demonstrated lower acceleration amplitudes,acceleration amplification factors,acceleration response spectra,and dynamic amplification factors compared with RC-supported slopes.Moreover,the dynamic bending moments of ECC anti-slide piles were approximately 70%-90% of those of RC anti-slide piles.Significant differences were also observed between the two support systems in terms of dynamic earth pressure distribution and residual displacement development.These findings confirmed the potential of ECC as an advanced material for enhancing high-steep slope stability in mountainous regions,providing a valuable reference for slope stabilization and landslide mitigation in seismic areas.展开更多
Seismic responses of utility tunnel-soil system were studied via shaking table model tests with considerations of two kinds of double box utility tunnels:with and without joint connections.These two testing utility tu...Seismic responses of utility tunnel-soil system were studied via shaking table model tests with considerations of two kinds of double box utility tunnels:with and without joint connections.These two testing utility tunnel models were made of galvanized iron wire and micro-concrete,and the ground was simulated by the dry standard sand through layered tamping treatment.The utility tunnel-soil system was subjected to horizontal vibration in uniaxial direction perpendicular to the longitudinal direction of tunnel model.Via instrumentations of earth pressure gauges,accelerometers and strain gauges,the earth pressure response,acceleration response and bending moment response were measured.The testing results show that the joint connections in the utility tunnel along the longitudinal direction play an important role in determining the characteristic of earth pressure response and bending moment response,whereas the effect of joint connections on acceleration response is less significant.In addition,the partition wall exhibits the consistent acceleration response with the side-wall of double box utility tunnel model under seismic condition.Based on the testing results,it is suggested that the joint connection should be taken reasonably into consideration during design and construction for engineering practice.展开更多
In geotechnical engineering,the transparent soil(also called transparent media)technique is an effective tool for conducting experimental tests and investigating the displacement characteristics and stress distributio...In geotechnical engineering,the transparent soil(also called transparent media)technique is an effective tool for conducting experimental tests and investigating the displacement characteristics and stress distribution of soils.It plays a vital role in the observation of internal soil deformations.This study aims to briefly review the current state of some of the common materials used to formulate transparent soil models and the application of the transparent soil technique to underground construction over the last 20 years.To this end,the basic concepts of transparent soils are introduced.Then,several representative applications of transparent soil in underground construction(i.e.,soil deformations induced by the penetration of pile foundations,tunnel excavation-induced movements,and structural responses caused by braced excavations)are presented.Because some research gaps may exist,certain potential research topics are proposed.This review can serve as a guideline for researchers performing experiments using transparent soils.展开更多
The underground structure in coral sand is threatened by earthquake.The special dynamic characteristics of coral sand were realized by finite difference program.Specifically,the stress–strain loops,shear modulus atte...The underground structure in coral sand is threatened by earthquake.The special dynamic characteristics of coral sand were realized by finite difference program.Specifically,the stress–strain loops,shear modulus attenuation and hysteresis behaviour of coral sand were simulated using hysteresis damping.On this basis,numerical models were established to study the seismic response of the rectangular underground structure in coral sand,and the fluid–solid coupling and soil-structure interaction were considered.The results illustrate that the increasing relative density of coral sand foundation reduces the excess pore water pressure(EPWP),but amplifies the horizontal dynamic soil pressure of the coral sand-underground structure system.The increase in the permeability coefficient of coral sand reduces the EPWP accumulation,which leads to an increase of the stiffness and a decrease of the acceleration amplification of coral sand sites.展开更多
The three-dimensional effects of pile head and the applicability of plane-section assumption are main problems in low-strain dynamic tests on cast-in-situ concrete thin-wall pipe piles.The velocity and displacement re...The three-dimensional effects of pile head and the applicability of plane-section assumption are main problems in low-strain dynamic tests on cast-in-situ concrete thin-wall pipe piles.The velocity and displacement responses were calculated by a theoretical formula deduced by the authors.The frequency and influencing factor of high-frequency interference were analyzed.A numerical method was established to calculate the peak value and arrival time of incoming waves on top of the piles.The regularity along circumferential and the influence of radius or impulse width were studied.The applicability of plane-section assumption was investigated by comparison of velocity responses at different points in the sections at different depths.The waveform of velocity response at different points forked after the first peak,indicating that the propagation of stress waves did not well meet the plane-section assumption.展开更多
基金the funding support from the National Natural Science Foundation of China(Grant No.52308340)Chongqing Talent Innovation and Entrepreneurship Demonstration Team Project(Grant No.cstc2024ycjh-bgzxm0012)the Science and Technology Projects supported by China Coal Technology and Engineering Chongqing Design and Research Institute(Group)Co.,Ltd.(Grant No.H20230317).
文摘Accurate prediction of landslide displacement is crucial for effective early warning of landslide disasters.While most existing prediction methods focus on time-series forecasting for individual monitoring points,there is limited research on the spatiotemporal characteristics of landslide deformation.This paper proposes a novel Multi-Relation Spatiotemporal Graph Residual Network with Multi-Level Feature Attention(MFA-MRSTGRN)that effectively improves the prediction performance of landslide displacement through spatiotemporal fusion.This model integrates internal seepage factors as data feature enhancements with external triggering factors,allowing for accurate capture of the complex spatiotemporal characteristics of landslide displacement and the construction of a multi-source heterogeneous dataset.The MFA-MRSTGRN model incorporates dynamic graph theory and four key modules:multilevel feature attention,temporal-residual decomposition,spatial multi-relational graph convolution,and spatiotemporal fusion prediction.This comprehensive approach enables the efficient analyses of multi-source heterogeneous datasets,facilitating adaptive exploration of the evolving multi-relational,multi-dimensional spatiotemporal complexities in landslides.When applying this model to predict the displacement of the Liangshuijing landslide,we demonstrate that the MFA-MRSTGRN model surpasses traditional models,such as random forest(RF),long short-term memory(LSTM),and spatial temporal graph convolutional networks(ST-GCN)models in terms of various evaluation metrics including mean absolute error(MAE=1.27 mm),root mean square error(RMSE=1.49 mm),mean absolute percentage error(MAPE=0.026),and R-squared(R^(2)=0.88).Furthermore,feature ablation experiments indicate that incorporating internal seepage factors improves the predictive performance of landslide displacement models.This research provides an advanced and reliable method for landslide displacement prediction.
基金supported by the National Natural Science Foundation of China (no.51622803 and 51420105013)
文摘An analytical method is developed to investigate the dynamic response of a pile subjected to harmonic vertical loading.The pile is modeled as a one-dimensional（1D）elastic rod.The elastic soil is divided into a homogeneous half space underlying the base of pile and a series of infinitesimally thin layers along the vertical shaft of pile.The analytical solution for the soil-pile dynamic interaction problem is obtained by the method of Hankel transformation.The proposed solution is compared with the classical plane strain solution.Arithmetical examples are presented to demonstrate the sensitivity of the vertical impedance of the pile to relevant parameters.
基金supported by the Fundamental Research Funds for the Central Universities(Grant Nos.2022CDJQY-012).
文摘In recent years,the development and construction of island reefs have been flourishing.Due to the remoteness of island reefs from the mainland,the scarcity of building materials,and the high transportation costs,it is imperative to use local marine resources,and the potential value and status of coral mud on island reefs,which is formed by the remains of corals and other biological entities,is becoming increasingly prominent.Utilization and optimization of natural resources on island reefs have become a brand-new research direction and challenge.This article mainly focuses on the development of a new type of green engineering material,coral mud,for use in building surface layers.Thickness effects,PVA fiber(vinylon staple fiber)modification,and HPMC(Hydroxypropyl Methyl Cellulose)adhesive modification are taken into consideration.Through laboratory tests and image processing technology,fractal theory,and electron microscopy experiments,the macro-meso-microscopic multi-scale cracking rules of the coral mud surface layer and the optimization modification rules of PVA fibers and HPMC adhesives are revealed.The results demonstrate that the performance of the coral mud surface layer is superior to that of the kaolin surface layer,and the 10 mm thickness performs better than the 5 mm and 20 mm thicknesses.As the thickness of the coral mud surface layer increases,the contact between coral mud particles becomes denser,the scale of surface micro-cracks decreases,and the number of micro-pores decreases.PVA fibers can effectively inhibit the further development of macro and micro cracks and play a good bridging role.There is a bonding and adhesion relationship between coral mud and PVA fibers,and they have a good synergistic effect in inhibiting macro and mesoscopic cracks.With the increase in HPMC adhesive content,the number of micro-cracks and the scale of micro-cracks decrease accordingly,and the structure and performance of the coral mud surface layer are further improved.Overall,PVA fibers are more effective than HPMC adhesives in inhibiting the cracking of the coral mud surface layer.This provides valuable guidance for the development and application of coral mud in wall surface materials.
基金supported by the National Natural Science Foundation of China(Nos.52308352,52238009,and 52108321)the Jiangxi Provincial Natural Science Foundation of China(No.20232BAB214082)+1 种基金the Open Research Fund Program of Guangdong Key Laboratory of Earthquake Engineering and Application Technology(No.2020B1212060071)the Science&Technology Project of the Education Department of Jiangxi Province(No.GJJ2200681),China.
文摘A series of small-scale 1g X-section cast-in-place concrete(XCC)pile-penetration model tests were conducted to study the effects of soil density and pile geometry on the lateral responses of an existing pile and the variations in surrounding soil stress.The results showed that the bending patterns of existing XCC piles varied with penetration depth.The lateral response of the existing pile was sensitive to the change in relative density and pile geometry.For example,the bending moment of the existing pile increased along with these parameters.The development of the radial stressσ′r/σ′v0 of the soil around an existing pile showed different trends at various depths during the penetration of the adjacent pile.Moreover,the change in radial stress during the penetration of the XCC pile did not exhibit the“h/R effect”that was observed in the free-field soil,due to the shielding effect of the existing piles.The peak value of radial stressσ′r_max/σ′v0 decreased exponentially as the radial distance r/R increased.The attenuation ofσ′r_max/σ′v0 with r/R in the loose sand was faster than in the medium-dense or dense sands.Theσ′r_max/σ′v0 at the same soil location increased with the cross-section geometry parameter.
基金This research was funded through the National Natural Science Foundation of China(Grant Nos.52108299 and 52178312)the China Postdoctoral Science Foundation(Grant No.2021M693740)the Basal Research Fund Support by Chongqing University.
文摘The performance of geosynthetic-reinforced embankments under traffic moving loads is always a hotspot in the geotechnical engineering field.A three-dimensional(3D)model of a geosynthetic-reinforced embankment without drainage consolidation was established using the finite element software ABAQUS.In this model,the traffic loads were simulated by two moving loads of rectangular pattern,and their amplitude,range,and moving speed were realized by a Fortran subroutine.The embankment fill was simulated by an equivalent linear viscoelastic model,which can reflect its viscoelasticity.The geogrid was simulated by the truss element,and the geocell was simulated by the membrane element.Infinite elements were utilized to weaken the boundary effect caused by the model geometry at the boundaries.Validation of the established numerical model was conducted by comparing the predicted deformations in the cross-section of the geosynthetic-reinforced embankment with those from the existing literature.On this basis,the dynamic stress and strain distribution in the pavement structure layer of the geosynthetic-reinforced embankment under a moving load was also analyzed.Finally,a parametric study was conducted to examine the influences of the different types of reinforcement,overload,and the moving load velocity on the geosynthetic-reinforced embankment.
基金financial support from National Major Scientific Instruments Development Project of China(5202780029)Program of Distinguished Young Scholars Natural Science Foundation of Chongqing China(cstc2020jcyj-jq0087)+1 种基金National Natural Science Foundation of China(52078086)Chongqing Construction Science and Technology Plan Project(2019-0045)。
文摘This paper presents a confidence ellipse-based method to evaluate the similarity of soil parametric data using the database from the site investigation reports.Then,the obtained similarity assessment results of parametric data are used to further estimate the site similarity via two proposed strategies,namely the mean and weighted mean approaches.The former referred to the average of parametric data similarity degrees,while the latter was the weighted average,and the weight was calculated using the coefficient of variation(COV)of each parameter.For illustration,the liquidity index(LI)dataset was firstly used to explore the performance of the presented method in the evaluation of parametric data similarity.Subsequently,the site similarity was assessed and the effects of numbers and weights of selected parameters for study were systematically studied.Lastly,the transformation models about the relationships between Cc and x as well as between Cc and e0 were constructed to illustrate the application of the similarity analysis in reduction of transformation uncertainty.Results show that the greatest site similarity degree is at about 0.76 in this study,and the maximum decrease of transformation uncertainty can reach up to 18%and 25.5%as union parametric data similarity degree increases.Moreover,the site similarity degree represents the whole similarity between two different sites,and the presented union parameter similarity degree maintains a good agreement with transformation uncertainty.
基金This work was supported by the National Key Research and Development Program of China with Grant Number 2016YFE0200100the National Natural Science Foundation of China with Grant Numbers 51622803,51708064the Fundamental Research Funds for the Central Universities with Grant Numbers 106112017CDJXY200002,106112016CDJXZ208821.
文摘An analytical solution is developed in this paper to conduct the low-strain integrity testing for a pipe pile with multiple defects.The derived solution allows simulating the pipe pile as a three-dimensional model by considering the wave propagation in the vertical,circumferential and radial directions.Analytical solutions of the pile are obtained by the Laplace transform and separation of variables.Accordingly,time-domain responses of the solution are deduced by the inverse Fourier transform numerically.The solution is validated against the published solutions for an intact pile and a pile with a single defect.Parametric studies are conducted to identify and characterize the velocity responses on the top of pipe piles with multiple defects.Numerical results suggest that the reflected waves generated by the deep defects are affected by the secondary reflections from the shallow defects.A new detecting method is proposed to decrease the influence of high-frequency interferences and to predict the defective depth,which suggests putting the receiver at the point of 90°along the circumferential direction.
基金The authors would like to acknowledge the financial support provided by the National Natural Science Foundation of China(Grant No.41977240)the Fundamental Research Funds for the Central Universities(Grant No.B200202090).
文摘In this study, a three-dimensional (3D) finite element modelling (FEM) analysis is carried out to investigate the effects of soil spatial variability on the response of retaining walls and an adjacent box culvert due to a braced excavation. The spatial variability of soil stiffness is modelled using a variogram and calibrated by high-quality experimental data. Multiple random field samples (RFSs) of soil stiffness are generated using geostatistical analysis and mapped onto a finite element mesh for stochastic analysis of excavation-induced structural responses by Monte Carlo simulation. It is found that the spatial variability of soil stiffness can be described by an exponential variogram, and the associated vertical correlation length is varied from 1.3 m to 1.6 m. It also reveals that the spatial variability of soil stiffness has a significant effect on the variations of retaining wall deflections and box culvert settlements. The ignorance of spatial variability in 3D FEM can result in an underestimation of lateral wall deflections and culvert settlements. Thus, the stochastic structural responses obtained from the 3D analysis could serve as an effective aid for probabilistic design and analysis of excavations.
基金supported by the National Natural Science Foundation of China(Grant Nos.U2268213,52178312)the S&T Program of Hebei(Grant No.23567602H)。
文摘Engineered cementitious composites(ECC)are highly ductile materials with excellent crack control capabilities,making them well-suited for structural applications requiring enhanced durability and resilience.In mountainous engineering construction,stabilizing high-steep slopes presents a significant challenge,with sheet-pile walls commonly employed to improve seismic stability.To assess the effectiveness of ECC in such applications,this study conducted two comparative shaking table tests to investigate the seismic performance of high-steep slopes supported by ECC sheet-pile walls.The failure modes,acceleration responses,dynamic earth pressure responses,bending moments of anti-sliding piles,and lateral displacement responses of the ECC-supported slope were systematically analyzed and compared with those of slopes supported by traditional reinforced concrete(RC)sheet-pile walls.The test results indicate that ECC-supported slopes exhibited significantly better seismic performance than RC-supported slopes.ECC sheet-pile wall maintained structural integrity at higher seismic intensities(PGA=1.2g)compared with RC walls,which failed at PGA=1.0g.Under the same seismic loading,ECC-supported slopes demonstrated lower acceleration amplitudes,acceleration amplification factors,acceleration response spectra,and dynamic amplification factors compared with RC-supported slopes.Moreover,the dynamic bending moments of ECC anti-slide piles were approximately 70%-90% of those of RC anti-slide piles.Significant differences were also observed between the two support systems in terms of dynamic earth pressure distribution and residual displacement development.These findings confirmed the potential of ECC as an advanced material for enhancing high-steep slope stability in mountainous regions,providing a valuable reference for slope stabilization and landslide mitigation in seismic areas.
基金supported by Natural Science Foundation of China(Grant Nos.52078086 and 51778092)Innovation Group Science Foundation of the Natural Science Foundation of Chongqing,China(Grant No.cstc2020jcyj-cxttX0003)State Education Ministry and the Fundamental Research Funds for the Central Universities(2019CDJSK04XK23).
文摘Seismic responses of utility tunnel-soil system were studied via shaking table model tests with considerations of two kinds of double box utility tunnels:with and without joint connections.These two testing utility tunnel models were made of galvanized iron wire and micro-concrete,and the ground was simulated by the dry standard sand through layered tamping treatment.The utility tunnel-soil system was subjected to horizontal vibration in uniaxial direction perpendicular to the longitudinal direction of tunnel model.Via instrumentations of earth pressure gauges,accelerometers and strain gauges,the earth pressure response,acceleration response and bending moment response were measured.The testing results show that the joint connections in the utility tunnel along the longitudinal direction play an important role in determining the characteristic of earth pressure response and bending moment response,whereas the effect of joint connections on acceleration response is less significant.In addition,the partition wall exhibits the consistent acceleration response with the side-wall of double box utility tunnel model under seismic condition.Based on the testing results,it is suggested that the joint connection should be taken reasonably into consideration during design and construction for engineering practice.
基金supported by the Key Laboratory of Mining Disaster Prevention and Control(No.MDPC201902)Chongqing Construction Science and Technology Plan Project(No.2019-0045)+1 种基金Graduate Research and Innovation Foundation of Chongqing(No.CYS18024)Fundamental Research Funds for the Central Universities(Grant ID 2019CDJDTM0007).
文摘In geotechnical engineering,the transparent soil(also called transparent media)technique is an effective tool for conducting experimental tests and investigating the displacement characteristics and stress distribution of soils.It plays a vital role in the observation of internal soil deformations.This study aims to briefly review the current state of some of the common materials used to formulate transparent soil models and the application of the transparent soil technique to underground construction over the last 20 years.To this end,the basic concepts of transparent soils are introduced.Then,several representative applications of transparent soil in underground construction(i.e.,soil deformations induced by the penetration of pile foundations,tunnel excavation-induced movements,and structural responses caused by braced excavations)are presented.Because some research gaps may exist,certain potential research topics are proposed.This review can serve as a guideline for researchers performing experiments using transparent soils.
基金supported by the National Natural Science Foundation of China(Grant Nos.52178312,51878103,51778092,41831282)Innovation Group Science Foundation of the Natural Science Foundation of Chongqing,China(Grant No.cstc2020jcyj-cxttX0003).
文摘The underground structure in coral sand is threatened by earthquake.The special dynamic characteristics of coral sand were realized by finite difference program.Specifically,the stress–strain loops,shear modulus attenuation and hysteresis behaviour of coral sand were simulated using hysteresis damping.On this basis,numerical models were established to study the seismic response of the rectangular underground structure in coral sand,and the fluid–solid coupling and soil-structure interaction were considered.The results illustrate that the increasing relative density of coral sand foundation reduces the excess pore water pressure(EPWP),but amplifies the horizontal dynamic soil pressure of the coral sand-underground structure system.The increase in the permeability coefficient of coral sand reduces the EPWP accumulation,which leads to an increase of the stiffness and a decrease of the acceleration amplification of coral sand sites.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.50679017,50778063)the Science Foundation of Jiangsu Province(No.BK2008040).
文摘The three-dimensional effects of pile head and the applicability of plane-section assumption are main problems in low-strain dynamic tests on cast-in-situ concrete thin-wall pipe piles.The velocity and displacement responses were calculated by a theoretical formula deduced by the authors.The frequency and influencing factor of high-frequency interference were analyzed.A numerical method was established to calculate the peak value and arrival time of incoming waves on top of the piles.The regularity along circumferential and the influence of radius or impulse width were studied.The applicability of plane-section assumption was investigated by comparison of velocity responses at different points in the sections at different depths.The waveform of velocity response at different points forked after the first peak,indicating that the propagation of stress waves did not well meet the plane-section assumption.
