This paper is focused on the behavior of geosynthetic-reinforced and column-supported （GRCS） earth platforms in soft soil. By analyzing the data of a 15-month long field monitoring project, the bearing behavior and ...This paper is focused on the behavior of geosynthetic-reinforced and column-supported （GRCS） earth platforms in soft soil. By analyzing the data of a 15-month long field monitoring project, the bearing behavior and effectiveness of GRCS earth platforms are discussed in detail. It can be found that the soil arching is generated when the filling reaches a certain height. The measured pressure acting on the soil in the center of four piles was smaller than that acting on the soil between two piles. The elongation and the tension of the geogrid located in the soil between piles are both larger than the corresponding values on the pile top. The skin friction of piles is relatively small in the soil layer with low strength and the load transfer of the axial force in those layers is significant; meanwhile, the opposite situation occurs in the soil layer with high strength. The pore water pressure at shallow locations increases slightly with the filling height and is greatly affected by the increasing filling load. The layered settlement is directly proportional to the filling height, and the corresponding amount is relevant to the locations and the properties of specific soil layers. Additionally, the lateral displacement of the embankment increases with greater loading and decreases with increased depth. These suggest that the use of GRCS system can reduce lateral displacements and enhance the stability of an embankment significantly.展开更多
Geosynthetic-reinforced and pile-supported （GRPS） embankment has been increasingly constructed in a large number of regions and for a wide range of projects in the past decades. However, many disadvantages are expos...Geosynthetic-reinforced and pile-supported （GRPS） embankment has been increasingly constructed in a large number of regions and for a wide range of projects in the past decades. However, many disadvantages are exposed through a lot of applications on conventional technique of GRPS embankment （called CT embankment）, i.e., intolerable settlement and lateral displacement, low geosynthetic efficiency, etc. In view of these disadvantages, the fixed geosynthetic technique of GRPS embankment （called FGT embankment） is developed in this work. In this system, the geosynthetic is fixed on the pile head by the steel bar fulcrum and concrete fixed top. The principles and construction techniques involved in the FGT embankment are described firstly. Then, the numerical analysis method and two-stage analysis method are used to study the performance of FGT embankment, respectively. It is shown that the FGT embankment can provide a better improvement technique to construct a high embankment over soft ground.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
To discuss the soil arching effect on the load transferring model and sharing ratios by the piles and inter-pile subsoil in the bidirectionally reinforced composite ground, the forming mechanism, mechanical behavior a...To discuss the soil arching effect on the load transferring model and sharing ratios by the piles and inter-pile subsoil in the bidirectionally reinforced composite ground, the forming mechanism, mechanical behavior and its effect factors were discussed in detail. Then, the unified strength theory was introduced to set up the elastoplastic equilibrium differential equation of the subsoil under the limit equilibrium state. And from the equation, the solutions were derived with the corresponding formulas presented to calculate the earth pressure over and beneath the horizontal reinforced cushion or pillow, the stress of inter-pile subsoil and the pile-soil stress ratio. Based on the obtained solutions and measured data from an engineering project, the influence rules by the soil property parameters (i.e., the cohesion c and internal friction angle φ) and pile spacing on the pile-soil stress ratio n were discussed respectively. The results show that to improve the load sharing ratio by the piles, the more effective means for filling materials with a larger value of φ is to increase the ratio of pile cap size to spacing, while to reduce the pile spacing properly and increase the value of cohesion c is advisable for those filling materials with a smaller value of φ.展开更多
Soils are actually unsaturated in nature. In the present study, a stability analysis of a geosynthetic-reinforced slope in unsaturated soils subjected to various steady flow conditions is conducted based on limit anal...Soils are actually unsaturated in nature. In the present study, a stability analysis of a geosynthetic-reinforced slope in unsaturated soils subjected to various steady flow conditions is conducted based on limit analysis. Work rate by apparent cohesion due to matric suction is calculated based on the effective stress-based equation. Analytical expression of the required cohesion/stability number of slope is derived from the energy balance equation. An optimization code is programmed to capture the optimized solution of the stability number. Comparison is made to verify the present work and a parametric analysis is conducted to investigate the effects of soil type, infilitration rate, reinforcement strength and soil suction on slope stability afterwards. A set of numerical solutions is presented at the end of the paper for preliminary design purposes.展开更多
Settlement prediction of geosynthetic-reinforced soil(GRS)abutments under service loading conditions is an arduous and challenging task for practicing geotechnical/civil engineers.Hence,in this paper,a novel hybrid ar...Settlement prediction of geosynthetic-reinforced soil(GRS)abutments under service loading conditions is an arduous and challenging task for practicing geotechnical/civil engineers.Hence,in this paper,a novel hybrid artificial intelligence(AI)-based model was developed by the combination of artificial neural network(ANN)and Harris hawks’optimisation(HHO),that is,ANN-HHO,to predict the settlement of the GRS abutments.Five other robust intelligent models such as support vector regression(SVR),Gaussian process regression(GPR),relevance vector machine(RVM),sequential minimal optimisation regression(SMOR),and least-median square regression(LMSR)were constructed and compared to the ANN-HHO model.The predictive strength,relalibility and robustness of the model were evaluated based on rigorous statistical testing,ranking criteria,multi-criteria approach,uncertainity analysis and sensitivity analysis(SA).Moreover,the predictive veracity of the model was also substantiated against several large-scale independent experimental studies on GRS abutments reported in the scientific literature.The acquired findings demonstrated that the ANN-HHO model predicted the settlement of GRS abutments with reasonable accuracy and yielded superior performance in comparison to counterpart models.Therefore,it becomes one of predictive tools employed by geotechnical/civil engineers in preliminary decision-making when investigating the in-service performance of GRS abutments.Finally,the model has been converted into a simple mathematical formulation for easy hand calculations,and it is proved cost-effective and less time-consuming in comparison to experimental tests and numerical simulations.展开更多
To understand the deformational behaviours of geosynthetics-reinforced soil retaining walls(GRS RWs),a series of plane-strain shaking table tests was conducted on retaining wall models.The backfill of the models was m...To understand the deformational behaviours of geosynthetics-reinforced soil retaining walls(GRS RWs),a series of plane-strain shaking table tests was conducted on retaining wall models.The backfill of the models was made of poorly graded gravel.Deformations and strains in the gravelly backfill induced by seismic loading are recorded in real time,which are of importance to understand the seismic strength and stability of the GRS RW systems,as strain localisation development in the backfill and foundation is related to the degree of strength degradation of the system.In the present study,we aimed at quantifying the induced deformations of the GRS RW models due to shaking.Digital image correlation(DIC)technique was then employed to analyse and provide full-field deformation and motion images with the models.It is demonstrated that,unlike conventional contact devices that are yet limited to provide quantities of a singular and fixed location,DIC provides deformation and motion of the area of interests to reveal the evolution of localisation.展开更多
Geosynthetic-reinforced soil retaining walls(GSRWs)have been widely used in civil engineering projects.However,as the climate changes,extreme weather conditions and natural hazards are likely to become more frequent o...Geosynthetic-reinforced soil retaining walls(GSRWs)have been widely used in civil engineering projects.However,as the climate changes,extreme weather conditions and natural hazards are likely to become more frequent or intense,posing a huge threat to the stability of GSRWs.In this paper,the effect of groundwater level fluctuations on the seismic response of GSRWs is investigated.First,a dynamic numerical model was established and validated through centrifugal shaking-table test results.Using the established numerical model,the seismic response of GSRWs under four different groundwater level conditions was then investigated,i.e.,an earthquake occurring at a low groundwater level(Case LW),an earthquake occurring when the groundwater level rises(Case RW),an earthquake occurring at a high groundwater level(Case HW),and an earthquake occurring when the groundwater level drops(Case DW).The results show that the GSRW in Case DW has the worst seismic stability because of the drag forces generated by the water flowing to the outside of the GSRW.For Case RW,deformation of the GSRW under earthquake forces was prevented by the drag forces generated by the water flowing to the inside of the GSRW and the water pressure acting on the outside of the facing,giving the GSRW the best seismic stability in this case.Compared with Case LW,the seismic stability of a GSRW in Case HW is worse,because the high groundwater level will generate excess pore-water pressure during an earthquake.On this basis,we provide engineering design suggestions to be considered by practitioners.展开更多
基金Acknowledgements The authors gratefully acknowledge the financial support for this work provided by the National Natural Science Foundation of China （Grant Nos. 41172260, 41372292 and 51108393）, the National Basic Research Program of China （Grant No. 2008CB425801）, and the Specialized Research Fund for the Doctoral Program of Higher Education （Grant No. 20110184110018） as well as the Doctoral Student Innovation Fund of Southwest Jiaotong University. The physical labor and support from Master Han-bing Wang, Xiu-jnn Long and Wei Lai are greatly appreciated.
文摘This paper is focused on the behavior of geosynthetic-reinforced and column-supported （GRCS） earth platforms in soft soil. By analyzing the data of a 15-month long field monitoring project, the bearing behavior and effectiveness of GRCS earth platforms are discussed in detail. It can be found that the soil arching is generated when the filling reaches a certain height. The measured pressure acting on the soil in the center of four piles was smaller than that acting on the soil between two piles. The elongation and the tension of the geogrid located in the soil between piles are both larger than the corresponding values on the pile top. The skin friction of piles is relatively small in the soil layer with low strength and the load transfer of the axial force in those layers is significant; meanwhile, the opposite situation occurs in the soil layer with high strength. The pore water pressure at shallow locations increases slightly with the filling height and is greatly affected by the increasing filling load. The layered settlement is directly proportional to the filling height, and the corresponding amount is relevant to the locations and the properties of specific soil layers. Additionally, the lateral displacement of the embankment increases with greater loading and decreases with increased depth. These suggest that the use of GRCS system can reduce lateral displacements and enhance the stability of an embankment significantly.
基金Foundation item： Project（51278216） supported by the National Natural Science Foundation of China Project（11-2-05） supported by the Scientific and Technological Project for Shanxi Communication Construction, China Project（HF-08-01-2011-240） supported by the Graduates＇ Innovation Fund of Huazhong University of Science and Technology, China
文摘Geosynthetic-reinforced and pile-supported （GRPS） embankment has been increasingly constructed in a large number of regions and for a wide range of projects in the past decades. However, many disadvantages are exposed through a lot of applications on conventional technique of GRPS embankment （called CT embankment）, i.e., intolerable settlement and lateral displacement, low geosynthetic efficiency, etc. In view of these disadvantages, the fixed geosynthetic technique of GRPS embankment （called FGT embankment） is developed in this work. In this system, the geosynthetic is fixed on the pile head by the steel bar fulcrum and concrete fixed top. The principles and construction techniques involved in the FGT embankment are described firstly. Then, the numerical analysis method and two-stage analysis method are used to study the performance of FGT embankment, respectively. It is shown that the FGT embankment can provide a better improvement technique to construct a high embankment over soft ground.
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Project (07JJ4015) supported by the Natural Science Foundation of Hunan Province, China
文摘To discuss the soil arching effect on the load transferring model and sharing ratios by the piles and inter-pile subsoil in the bidirectionally reinforced composite ground, the forming mechanism, mechanical behavior and its effect factors were discussed in detail. Then, the unified strength theory was introduced to set up the elastoplastic equilibrium differential equation of the subsoil under the limit equilibrium state. And from the equation, the solutions were derived with the corresponding formulas presented to calculate the earth pressure over and beneath the horizontal reinforced cushion or pillow, the stress of inter-pile subsoil and the pile-soil stress ratio. Based on the obtained solutions and measured data from an engineering project, the influence rules by the soil property parameters (i.e., the cohesion c and internal friction angle φ) and pile spacing on the pile-soil stress ratio n were discussed respectively. The results show that to improve the load sharing ratio by the piles, the more effective means for filling materials with a larger value of φ is to increase the ratio of pile cap size to spacing, while to reduce the pile spacing properly and increase the value of cohesion c is advisable for those filling materials with a smaller value of φ.
基金Project(2019M650011)supported by China Postdoctoral Science FoundationProject(51421005)supported by the Science Fund for Creative Research Groups of the National Natural Science Foundation of ChinaProject(2015CB057902)supported by the National Basic Research Program of China
文摘Soils are actually unsaturated in nature. In the present study, a stability analysis of a geosynthetic-reinforced slope in unsaturated soils subjected to various steady flow conditions is conducted based on limit analysis. Work rate by apparent cohesion due to matric suction is calculated based on the effective stress-based equation. Analytical expression of the required cohesion/stability number of slope is derived from the energy balance equation. An optimization code is programmed to capture the optimized solution of the stability number. Comparison is made to verify the present work and a parametric analysis is conducted to investigate the effects of soil type, infilitration rate, reinforcement strength and soil suction on slope stability afterwards. A set of numerical solutions is presented at the end of the paper for preliminary design purposes.
文摘Settlement prediction of geosynthetic-reinforced soil(GRS)abutments under service loading conditions is an arduous and challenging task for practicing geotechnical/civil engineers.Hence,in this paper,a novel hybrid artificial intelligence(AI)-based model was developed by the combination of artificial neural network(ANN)and Harris hawks’optimisation(HHO),that is,ANN-HHO,to predict the settlement of the GRS abutments.Five other robust intelligent models such as support vector regression(SVR),Gaussian process regression(GPR),relevance vector machine(RVM),sequential minimal optimisation regression(SMOR),and least-median square regression(LMSR)were constructed and compared to the ANN-HHO model.The predictive strength,relalibility and robustness of the model were evaluated based on rigorous statistical testing,ranking criteria,multi-criteria approach,uncertainity analysis and sensitivity analysis(SA).Moreover,the predictive veracity of the model was also substantiated against several large-scale independent experimental studies on GRS abutments reported in the scientific literature.The acquired findings demonstrated that the ANN-HHO model predicted the settlement of GRS abutments with reasonable accuracy and yielded superior performance in comparison to counterpart models.Therefore,it becomes one of predictive tools employed by geotechnical/civil engineers in preliminary decision-making when investigating the in-service performance of GRS abutments.Finally,the model has been converted into a simple mathematical formulation for easy hand calculations,and it is proved cost-effective and less time-consuming in comparison to experimental tests and numerical simulations.
基金the Japan Society for the Promotion of Science and their financial support through the JSPS Fellowship Programme to conduct research activities at the University of Tokyo.
文摘To understand the deformational behaviours of geosynthetics-reinforced soil retaining walls(GRS RWs),a series of plane-strain shaking table tests was conducted on retaining wall models.The backfill of the models was made of poorly graded gravel.Deformations and strains in the gravelly backfill induced by seismic loading are recorded in real time,which are of importance to understand the seismic strength and stability of the GRS RW systems,as strain localisation development in the backfill and foundation is related to the degree of strength degradation of the system.In the present study,we aimed at quantifying the induced deformations of the GRS RW models due to shaking.Digital image correlation(DIC)technique was then employed to analyse and provide full-field deformation and motion images with the models.It is demonstrated that,unlike conventional contact devices that are yet limited to provide quantities of a singular and fixed location,DIC provides deformation and motion of the area of interests to reveal the evolution of localisation.
基金the National Natural Science Foundation of China(No.41877224)the China Scholarship Council(No.202006265003)the National Key Research and Development Program of China(No.2019YFC1509900)。
文摘Geosynthetic-reinforced soil retaining walls(GSRWs)have been widely used in civil engineering projects.However,as the climate changes,extreme weather conditions and natural hazards are likely to become more frequent or intense,posing a huge threat to the stability of GSRWs.In this paper,the effect of groundwater level fluctuations on the seismic response of GSRWs is investigated.First,a dynamic numerical model was established and validated through centrifugal shaking-table test results.Using the established numerical model,the seismic response of GSRWs under four different groundwater level conditions was then investigated,i.e.,an earthquake occurring at a low groundwater level(Case LW),an earthquake occurring when the groundwater level rises(Case RW),an earthquake occurring at a high groundwater level(Case HW),and an earthquake occurring when the groundwater level drops(Case DW).The results show that the GSRW in Case DW has the worst seismic stability because of the drag forces generated by the water flowing to the outside of the GSRW.For Case RW,deformation of the GSRW under earthquake forces was prevented by the drag forces generated by the water flowing to the inside of the GSRW and the water pressure acting on the outside of the facing,giving the GSRW the best seismic stability in this case.Compared with Case LW,the seismic stability of a GSRW in Case HW is worse,because the high groundwater level will generate excess pore-water pressure during an earthquake.On this basis,we provide engineering design suggestions to be considered by practitioners.
