In this study, the ultimate bearing capacity of shallow strip footings resting on a geosynthetic-reinforced soil mass subjected to inclined and eccentric combined loading is rigorously examined through the well-established method of lower bound limit analysis (LA) in conjunction with finite element (FE) and second-order cone programming (SOCP). Lower bound limit analysis formulation is modified to consider the ultimate tensile force of the geosynthetic layer in the soil mass so as to account for both pullout (sliding) and rupture (structural) modes of reinforcement failure. The effects of several parameters, including the embedment depth (u) and the ultimate tensile force (Tu) of the geosynthetic layer along with load inclination angle (α) and load eccentricity (e), on the bearing capacity ratio (BCR) and failure envelopes of the overlying shallow foundation are examined and discussed. The results generally show a marked increase in the ultimate bearing capacity of the surface footing against combined loading with the inclusion of a single geosynthetic layer. Results also reveal that a second intermediate reinforcement might be required to bear a dual performance against both vertical concentric and combined loading so as to more effectively support the footing.
{"title":"Bearing capacity of combined loading footings on geosynthetic-reinforced granular soil","authors":"B. Yaghoobi, H. Fathipour, M. Payan, R. Chenari","doi":"10.1680/jgein.22.00385","DOIUrl":"https://doi.org/10.1680/jgein.22.00385","url":null,"abstract":"In this study, the ultimate bearing capacity of shallow strip footings resting on a geosynthetic-reinforced soil mass subjected to inclined and eccentric combined loading is rigorously examined through the well-established method of lower bound limit analysis (LA) in conjunction with finite element (FE) and second-order cone programming (SOCP). Lower bound limit analysis formulation is modified to consider the ultimate tensile force of the geosynthetic layer in the soil mass so as to account for both pullout (sliding) and rupture (structural) modes of reinforcement failure. The effects of several parameters, including the embedment depth (u) and the ultimate tensile force (Tu) of the geosynthetic layer along with load inclination angle (α) and load eccentricity (e), on the bearing capacity ratio (BCR) and failure envelopes of the overlying shallow foundation are examined and discussed. The results generally show a marked increase in the ultimate bearing capacity of the surface footing against combined loading with the inclusion of a single geosynthetic layer. Results also reveal that a second intermediate reinforcement might be required to bear a dual performance against both vertical concentric and combined loading so as to more effectively support the footing.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2023-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41651032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The investigation of cyclic shear response on a geosynthetic–soil interface is important for reinforced soil structures. A stereoscopic geogrid with a thickened transverse-rib thickness increases the interaction with the soil compared with a planar geogrid. In this study, three-dimensional printing technology was used to produce stereoscopic geogrids with transverse-rib thicknesses of 5, 10, 15, and 20 mm. The influences of different cyclic shear displacement amplitudes (1, 3, 6, and 10 mm) and normal stresses (20, 40, and 60 kPa) on the direct shear tests under static and cyclic loading at the stereoscopic geogrid–sand interface were investigated. The results indicate that the maximum shear stress can be improved by the stereoscopic geogrid at larger cyclic shear displacement amplitudes. The effect of transverse-rib thickness on the fitted curves of the normalized interface shear stiffness and damping ratio was reversed. The cyclic shear process altered the relationship between apparent cohesiveness and transverse-rib thickness. The peak stress ratio of the stereoscopic geogrid–sand interface is proposed as a function of the transverse-rib thickness and maximum dilation angle.
{"title":"Cyclic response of stereoscopic geogrid–sand interface under static and cyclic loading","authors":"W. Zeng, F. Liu, M. Ying","doi":"10.1680/jgein.23.00009","DOIUrl":"https://doi.org/10.1680/jgein.23.00009","url":null,"abstract":"The investigation of cyclic shear response on a geosynthetic–soil interface is important for reinforced soil structures. A stereoscopic geogrid with a thickened transverse-rib thickness increases the interaction with the soil compared with a planar geogrid. In this study, three-dimensional printing technology was used to produce stereoscopic geogrids with transverse-rib thicknesses of 5, 10, 15, and 20 mm. The influences of different cyclic shear displacement amplitudes (1, 3, 6, and 10 mm) and normal stresses (20, 40, and 60 kPa) on the direct shear tests under static and cyclic loading at the stereoscopic geogrid–sand interface were investigated. The results indicate that the maximum shear stress can be improved by the stereoscopic geogrid at larger cyclic shear displacement amplitudes. The effect of transverse-rib thickness on the fitted curves of the normalized interface shear stiffness and damping ratio was reversed. The cyclic shear process altered the relationship between apparent cohesiveness and transverse-rib thickness. The peak stress ratio of the stereoscopic geogrid–sand interface is proposed as a function of the transverse-rib thickness and maximum dilation angle.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2023-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42988096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The paper presents new insights into the particle kinematics and tribological aspects and their effects on the non-dilative interface shear response from novel experimental investigations. A custom-designed apparatus that enables image analysis of particulate-continuum materials interactions from the bottom of the interface plane while shearing was developed. The effect of influential factors on the frictional mechanism, particle kinematics, and subsequently on the friction coefficient was investigated by performing experiments on three types of sands at different normal stresses with a transparent acrylic sheet and smooth geomembrane. The results demonstrated that the frictional response of the acrylic sheet and geomembrane was comparable, indicating that their particle kinematics at the interface could be similar. However, the critical normal and peak shear stresses differed due to the materials' hardness. The image and micro-topographical analysis of the tested interfaces revealed that the box fixity, particle shape, and normal stress influence particle kinematics and shear-induced surface changes. The fixed box has shown restricted particle movements compared to the conventional box. Angular and smooth spherical particles exhibited lesser kinematics despite a huge difference in the shape and shear-induced surface changes. Rough spherical particles have larger displacements and shear-induced surface changes than smooth spherical particles.
{"title":"New insights into geotribology of non-dilative interfaces from novel experimental studies","authors":"L. Kandpal, P. Vangla","doi":"10.1680/jgein.23.00013","DOIUrl":"https://doi.org/10.1680/jgein.23.00013","url":null,"abstract":"The paper presents new insights into the particle kinematics and tribological aspects and their effects on the non-dilative interface shear response from novel experimental investigations. A custom-designed apparatus that enables image analysis of particulate-continuum materials interactions from the bottom of the interface plane while shearing was developed. The effect of influential factors on the frictional mechanism, particle kinematics, and subsequently on the friction coefficient was investigated by performing experiments on three types of sands at different normal stresses with a transparent acrylic sheet and smooth geomembrane. The results demonstrated that the frictional response of the acrylic sheet and geomembrane was comparable, indicating that their particle kinematics at the interface could be similar. However, the critical normal and peak shear stresses differed due to the materials' hardness. The image and micro-topographical analysis of the tested interfaces revealed that the box fixity, particle shape, and normal stress influence particle kinematics and shear-induced surface changes. The fixed box has shown restricted particle movements compared to the conventional box. Angular and smooth spherical particles exhibited lesser kinematics despite a huge difference in the shape and shear-induced surface changes. Rough spherical particles have larger displacements and shear-induced surface changes than smooth spherical particles.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2023-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47865207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. T. de Souza Paranhos, M. A. Aparício-Ardila, J. D. da Silva
Geotextile tubes have been presented as a viable alternative for dewatering sludge generated in different industries, characterized by having fine grain and high moisture content. The material commonly used to develop this system is woven geotextile due to its high strength properties. However, nonwoven geotextile tubes are a possible underexplored alternative that have good cost benefits. This paper presents the geometric and strain behaviour of two full-scale nonwoven geotextile tubes used for dewatering Water Treatment Plant (WTP) sludge. Four technologies were used to monitor the full-scale tests: ultrasonic sensor (US), perspective laser tracking (PLT), light detection and ranging (LIDAR) and draw-wire sensors (DWS). The geometric parameters of a quarter of the cross section and the strains in the geotextile were obtained during the sequential fills. These data were compared with results obtained from an analytical method based on membrane theory that considers the non-linear-elastic behaviour of the geotextile. The DWS and LIDAR technologies were the most suitable for monitoring the strains and shape of the tubes, respectively. Good agreement was found between analytical and experimental results, indicating the applicability of the adopted method to the design of the first filling cycle of the monitored nonwoven geotextile tubes.
{"title":"Geometric and strain behavior of full scale geotextile tubes for dewatering sludge","authors":"S. T. de Souza Paranhos, M. A. Aparício-Ardila, J. D. da Silva","doi":"10.1680/jgein.21.00102","DOIUrl":"https://doi.org/10.1680/jgein.21.00102","url":null,"abstract":"Geotextile tubes have been presented as a viable alternative for dewatering sludge generated in different industries, characterized by having fine grain and high moisture content. The material commonly used to develop this system is woven geotextile due to its high strength properties. However, nonwoven geotextile tubes are a possible underexplored alternative that have good cost benefits. This paper presents the geometric and strain behaviour of two full-scale nonwoven geotextile tubes used for dewatering Water Treatment Plant (WTP) sludge. Four technologies were used to monitor the full-scale tests: ultrasonic sensor (US), perspective laser tracking (PLT), light detection and ranging (LIDAR) and draw-wire sensors (DWS). The geometric parameters of a quarter of the cross section and the strains in the geotextile were obtained during the sequential fills. These data were compared with results obtained from an analytical method based on membrane theory that considers the non-linear-elastic behaviour of the geotextile. The DWS and LIDAR technologies were the most suitable for monitoring the strains and shape of the tubes, respectively. Good agreement was found between analytical and experimental results, indicating the applicability of the adopted method to the design of the first filling cycle of the monitored nonwoven geotextile tubes.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2023-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41636380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A mathematical model for heavy metal contaminants (HMCs) transport in a triple-layer composite liner with defective geomembrane under the non-isothermal condition is developed in this study, where the GMB/GCL/CCL (geomembrane, geosynthetic clay liner, and compacted clay liner) composite liner is adopted as an example and the Langmuir adsorption model is incorporated. The proposed model is solved by the finite difference approach, and its correctness is validated by comparison with the experimental results, an existing analytical solution, and another numerical method. Later, the transport behaviors of HMCs are explored with the established model. Compared with the isothermal condition, the non-isothermal condition enlarges the transport flux, but also reduces the concentration of HMCs. The relative concentration based on the Langmuir adsorption model is higher than that based on the linear adsorption model, which is related to the decrease of the retardation factor under the Langmuir adsorption model. Furthermore, the parametric study shows that when the leachate head ht is between 1.0 and 3.0 m, the defined breakthrough time tb increases by about 1.57 a with the increase of GCL thickness lg by 1 cm, and the tb increases by about 9.07 a with the increase of CCL thickness lc by 0.1 m.
{"title":"Heavy metal contaminants transport in a composite liner under the non-isothermal condition","authors":"W. Jiang, S. Ge, C. Feng, J. Li","doi":"10.1680/jgein.22.00396","DOIUrl":"https://doi.org/10.1680/jgein.22.00396","url":null,"abstract":"A mathematical model for heavy metal contaminants (HMCs) transport in a triple-layer composite liner with defective geomembrane under the non-isothermal condition is developed in this study, where the GMB/GCL/CCL (geomembrane, geosynthetic clay liner, and compacted clay liner) composite liner is adopted as an example and the Langmuir adsorption model is incorporated. The proposed model is solved by the finite difference approach, and its correctness is validated by comparison with the experimental results, an existing analytical solution, and another numerical method. Later, the transport behaviors of HMCs are explored with the established model. Compared with the isothermal condition, the non-isothermal condition enlarges the transport flux, but also reduces the concentration of HMCs. The relative concentration based on the Langmuir adsorption model is higher than that based on the linear adsorption model, which is related to the decrease of the retardation factor under the Langmuir adsorption model. Furthermore, the parametric study shows that when the leachate head ht is between 1.0 and 3.0 m, the defined breakthrough time tb increases by about 1.57 a with the increase of GCL thickness lg by 1 cm, and the tb increases by about 9.07 a with the increase of CCL thickness lc by 0.1 m.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2023-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47719016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Buried polyethylene pipes used in gas distribution systems can experience excessive wall strains when exposed to ground movements that can affect the performance of the pipes in service. This paper presents full-scale laboratory tests performed to investigate the responses of medium-density polyethylene (MDPE) gas-distribution pipes in dense sand when subjected to axial ground movements. Pipes buried in the sand in a large test box were pulled at the rates of 0.5 mm/min, 1 mm/min, and 2 mm/min to simulate the relative ground movements in the longitudinal direction. The test facility was instrumented to measure pulling force, pipe wall strains, and soil stresses. The measured pullout force was significantly higher than predicted using the equations recommended in current design guidelines, which is attributed to the increase of normal stress on the pipe wall by shear-induced dilation of interface soil. The cavity expansion theory was successfully applied to calculate the normal stress increase. The distribution of measured strains was nonlinear along the pipe length. Assuming a parabolic distribution of the strains, simplified equations were developed to calculate pullout resistances and pipe wall strains from the relative ground displacement. The developed method reasonably predicted the pipe strains measured during the tests.
{"title":"Strain assessment of polyethylene pipes in dense sand subjected to axial displacements","authors":"A. Reza, A. Dhar, M. Rahman","doi":"10.1680/jgein.22.00351","DOIUrl":"https://doi.org/10.1680/jgein.22.00351","url":null,"abstract":"Buried polyethylene pipes used in gas distribution systems can experience excessive wall strains when exposed to ground movements that can affect the performance of the pipes in service. This paper presents full-scale laboratory tests performed to investigate the responses of medium-density polyethylene (MDPE) gas-distribution pipes in dense sand when subjected to axial ground movements. Pipes buried in the sand in a large test box were pulled at the rates of 0.5 mm/min, 1 mm/min, and 2 mm/min to simulate the relative ground movements in the longitudinal direction. The test facility was instrumented to measure pulling force, pipe wall strains, and soil stresses. The measured pullout force was significantly higher than predicted using the equations recommended in current design guidelines, which is attributed to the increase of normal stress on the pipe wall by shear-induced dilation of interface soil. The cavity expansion theory was successfully applied to calculate the normal stress increase. The distribution of measured strains was nonlinear along the pipe length. Assuming a parabolic distribution of the strains, simplified equations were developed to calculate pullout resistances and pipe wall strains from the relative ground displacement. The developed method reasonably predicted the pipe strains measured during the tests.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2023-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46874844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The degradation behaviour of a 4.8 mm thick elastomeric bituminous geomembrane (BGM) immersed in pH 0.5, 9.5, and 11.5 synthetic mining solutions is examined over 26 months at 22, 40, 55 and 70°C. The low pH solution simulates the leach solutions found in copper, nickel, and uranium heap leach pads while the two high pH solutions simulate the chemistry and pH found in gold and silver heap leaching facilities. The mechanical, rheological, and chemical properties are examined at different incubation times to assess the degradation in the BGM at different temperatures. It is shown that the degradation rates of all properties are faster in pH 11.5 and 9.5 than in pH 0.5. Additionally, the BGM started to exhibit degradation in its mechanical properties even with a slightly degraded bitumen coat in all the mining solutions at elevated temperatures. The time to nominal failure of the BGM is predicted at different field temperatures using Arrhenius modelling. Due to the relatively fast degradation in the mechanical properties of the BGM, especially at temperatures above 50oC, the tensile strains in the BGM in the field should be limited so it can meet the required liner design life of heap leaching applications.
{"title":"Chemical durability of bituminous geomembranes (BGMs) in heap leach pad applications","authors":"F. Abdelaal, A. Samea","doi":"10.1680/jgein.22.00333","DOIUrl":"https://doi.org/10.1680/jgein.22.00333","url":null,"abstract":"The degradation behaviour of a 4.8 mm thick elastomeric bituminous geomembrane (BGM) immersed in pH 0.5, 9.5, and 11.5 synthetic mining solutions is examined over 26 months at 22, 40, 55 and 70°C. The low pH solution simulates the leach solutions found in copper, nickel, and uranium heap leach pads while the two high pH solutions simulate the chemistry and pH found in gold and silver heap leaching facilities. The mechanical, rheological, and chemical properties are examined at different incubation times to assess the degradation in the BGM at different temperatures. It is shown that the degradation rates of all properties are faster in pH 11.5 and 9.5 than in pH 0.5. Additionally, the BGM started to exhibit degradation in its mechanical properties even with a slightly degraded bitumen coat in all the mining solutions at elevated temperatures. The time to nominal failure of the BGM is predicted at different field temperatures using Arrhenius modelling. Due to the relatively fast degradation in the mechanical properties of the BGM, especially at temperatures above 50oC, the tensile strains in the BGM in the field should be limited so it can meet the required liner design life of heap leaching applications.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2023-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46324134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Embankment failures can be prevented by introducing geocomposites to act as drains. The effect of the geocomposite layer on the pore pressure distribution and surface displacements of an unsaturated embankment upon infiltration has been studied numerically using deterministic and probabilistic approaches. The inclusion of the geocomposite layer leads to an increase of suction below the interface and a decrease in suction above it by functioning both as a capillary barrier and a drainage layer, thereby reducing the surface displacements upon infiltration. The load in the form of rainfall and the resistance such as suction of the embankment material being variable leads to a variability in the displacements, so reliability analysis has been carried out using hydraulic permeability and soil water characteristic curve (SWCC) parameters as random variables. To assess the probability of failure (pf), surrogate model based on augmented radial basis function has been used. Probabilistic analysis revealed that the embankment with geocomposite has less pf compared to the one without geocomposite considering the rainfall infiltration. Moreover, sensitivity analysis predicted that SWCC parameters influence the pf of geosynthetics inclusive embankment under infiltration to a larger extent.
{"title":"Reliability analysis of compacted embankment with geocomposite under infiltration","authors":"R. Showkat, G. S. Sivakumar Babu","doi":"10.1680/jgein.22.00268","DOIUrl":"https://doi.org/10.1680/jgein.22.00268","url":null,"abstract":"Embankment failures can be prevented by introducing geocomposites to act as drains. The effect of the geocomposite layer on the pore pressure distribution and surface displacements of an unsaturated embankment upon infiltration has been studied numerically using deterministic and probabilistic approaches. The inclusion of the geocomposite layer leads to an increase of suction below the interface and a decrease in suction above it by functioning both as a capillary barrier and a drainage layer, thereby reducing the surface displacements upon infiltration. The load in the form of rainfall and the resistance such as suction of the embankment material being variable leads to a variability in the displacements, so reliability analysis has been carried out using hydraulic permeability and soil water characteristic curve (SWCC) parameters as random variables. To assess the probability of failure (pf), surrogate model based on augmented radial basis function has been used. Probabilistic analysis revealed that the embankment with geocomposite has less pf compared to the one without geocomposite considering the rainfall infiltration. Moreover, sensitivity analysis predicted that SWCC parameters influence the pf of geosynthetics inclusive embankment under infiltration to a larger extent.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2023-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47867679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Geogrid is a horizontal reinforcement material that is used in geosynthetic-reinforced pile-supported (GRPS) embankment in freeways with soft soil. Nevertheless, the long-term deformation mechanics of geogrid in the GRPS embankmentunder cyclic loading is not clear enough. This paper presents a laboratory model study of a GRPS embankment to study the long-term geogrid strain under cyclic loading. The effects of parameters such as number of load cycles, load frequency, geogrid layer numbers, and length of supporting piles on the long-term strain of geogrid were investigated. The results showed that geogrid strain increased with the number of load cycles, mainly developed in the first 10,000 load cycles and increased slowly in the later period. When the frequency was increased from 1 to 5 Hz, geogrid strain increased dramatically. When compared with the condition of a single geogrid layer, the upper layer of two geogrid layer caused a less geogrid strain. Compared with long piles and short piles GRPS embankments, a sufficient membrane effect of geogrid was found for long-short piles GRPS embankment. Finally, 95 percent prediction interval proposed in this paper could be expressed using a logarithmic function, providing a theoretical foundation for future engineering applications.
{"title":"Investigation on the long-term strain of geogrid in GRPS embankmentunder cyclic loading","authors":"K.-F. Liu, K.-R. Xue, Ming Wen, L. Wang","doi":"10.1680/jgein.22.00388","DOIUrl":"https://doi.org/10.1680/jgein.22.00388","url":null,"abstract":"Geogrid is a horizontal reinforcement material that is used in geosynthetic-reinforced pile-supported (GRPS) embankment in freeways with soft soil. Nevertheless, the long-term deformation mechanics of geogrid in the GRPS embankmentunder cyclic loading is not clear enough. This paper presents a laboratory model study of a GRPS embankment to study the long-term geogrid strain under cyclic loading. The effects of parameters such as number of load cycles, load frequency, geogrid layer numbers, and length of supporting piles on the long-term strain of geogrid were investigated. The results showed that geogrid strain increased with the number of load cycles, mainly developed in the first 10,000 load cycles and increased slowly in the later period. When the frequency was increased from 1 to 5 Hz, geogrid strain increased dramatically. When compared with the condition of a single geogrid layer, the upper layer of two geogrid layer caused a less geogrid strain. Compared with long piles and short piles GRPS embankments, a sufficient membrane effect of geogrid was found for long-short piles GRPS embankment. Finally, 95 percent prediction interval proposed in this paper could be expressed using a logarithmic function, providing a theoretical foundation for future engineering applications.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2023-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45584402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Y. Li, X. W. Tang, M. Fei, W. L. Chen, J. Liang, Q. Xiang
Woven slit-film geotextiles are often subjected to in-plane tensile loads in engineering applications, which may alter relevant permeability properties. The fractal model of the permeability coefficient in woven geotextiles is extended to predict the permeability coefficient of geotextiles subjected to uniaxial and lateral constrained uniaxial tensile strains. Based on the observation and summary of the variation of the pore size distribution pattern with tensile strain, the pore unit model is introduced. The model is expressed as the functions of the fractal dimension, pore size characteristics, physical parameters, and weft strain. A clamping device capable of applying uniaxial tension and laterally constrained uniaxial tension to geotextiles is invented. The validation of the model is verified using vertical permeability coefficient test and digital image analysis method on two selected woven geotextile samples. It is shown that the permeability coefficient increased with the increasing uniaxial tensile strain. Furthermore, the experimental values tended to change more significantly under laterally constrained uniaxial strain conditions for thinner geotextiles approaching the breaking strain and thicker geotextiles. The improved model can accurately predict the values and increasing rate of the permeability coefficient of woven geotextiles subjected to uniaxial and lateral constrained uniaxial tensile strains.
{"title":"Woven geotextiles permeability under uniaxial and laterally constrained conditions","authors":"K. Y. Li, X. W. Tang, M. Fei, W. L. Chen, J. Liang, Q. Xiang","doi":"10.1680/jgein.22.00381","DOIUrl":"https://doi.org/10.1680/jgein.22.00381","url":null,"abstract":"Woven slit-film geotextiles are often subjected to in-plane tensile loads in engineering applications, which may alter relevant permeability properties. The fractal model of the permeability coefficient in woven geotextiles is extended to predict the permeability coefficient of geotextiles subjected to uniaxial and lateral constrained uniaxial tensile strains. Based on the observation and summary of the variation of the pore size distribution pattern with tensile strain, the pore unit model is introduced. The model is expressed as the functions of the fractal dimension, pore size characteristics, physical parameters, and weft strain. A clamping device capable of applying uniaxial tension and laterally constrained uniaxial tension to geotextiles is invented. The validation of the model is verified using vertical permeability coefficient test and digital image analysis method on two selected woven geotextile samples. It is shown that the permeability coefficient increased with the increasing uniaxial tensile strain. Furthermore, the experimental values tended to change more significantly under laterally constrained uniaxial strain conditions for thinner geotextiles approaching the breaking strain and thicker geotextiles. The improved model can accurately predict the values and increasing rate of the permeability coefficient of woven geotextiles subjected to uniaxial and lateral constrained uniaxial tensile strains.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2023-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43767436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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