Twelves physical model tests were carried out to investigate the role of the type and arrangement of reinforcements on the behavior of back-to-back mechanically stabilized earth walls (BBMSEWs) supporting railway tracks. Six metal-strip reinforced BBMSEW models and six geogrid reinforced models were prepared with different reinforcement arrangements and then were vertically loaded to failure using wooden railway sleepers. The findings indicated that the reinforcement stiffness played a more prominent role in improving the bearing capacity than the pull-out capacity. The connection of two opposing walls with continuous reinforcements and the complete separation of them from each other were found to be the best and worst reinforcement arrangements. respectively, for improving the bearing capacity and reducing wall deformation in BBMSEWs. The respective use of these two arrangements mobilized the maximum and minimum forces in the reinforcements. Moreover, the creation of a proper connection between the opposing walls using continuous inextensible reinforcements or those with a sufficient overlap lengths were found to be efficient solutions to preventing the propagation of a failure plane across the back-to-back MSE walls.
{"title":"Behavior of back-to-back mechanically stabilized earth walls as railway embankments","authors":"M. Yazdandoust, F. Daftari","doi":"10.1680/jgein.23.00126","DOIUrl":"https://doi.org/10.1680/jgein.23.00126","url":null,"abstract":"Twelves physical model tests were carried out to investigate the role of the type and arrangement of reinforcements on the behavior of back-to-back mechanically stabilized earth walls (BBMSEWs) supporting railway tracks. Six metal-strip reinforced BBMSEW models and six geogrid reinforced models were prepared with different reinforcement arrangements and then were vertically loaded to failure using wooden railway sleepers. The findings indicated that the reinforcement stiffness played a more prominent role in improving the bearing capacity than the pull-out capacity. The connection of two opposing walls with continuous reinforcements and the complete separation of them from each other were found to be the best and worst reinforcement arrangements. respectively, for improving the bearing capacity and reducing wall deformation in BBMSEWs. The respective use of these two arrangements mobilized the maximum and minimum forces in the reinforcements. Moreover, the creation of a proper connection between the opposing walls using continuous inextensible reinforcements or those with a sufficient overlap lengths were found to be efficient solutions to preventing the propagation of a failure plane across the back-to-back MSE walls.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139439118","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}
M. S. Morsy, A. M. Elhanafy, S. S. Fathelbab, S. M. Ahmed
The effect of thermal-oxidative ageing on the in-isolation and in-soil stiffness is investigated for two high-density polyethylene (HDPE) and two polyester (PET) geogrids when incubated in an oven at 90oC. It is shown that the in-isolation and in-soil stiffness of three out of the four geogrids decreased during the 4-month ageing time with a faster degradation of the two PET geogrids. In contrast, one of the HDPE geogrids examined with thicker rib shows slower degradation compared to the PET counterparts. It is also shown that a geogrid might have a higher unaged stiffness, but less aged stiffness compared to another geogrid made of the same polymer type. It is suggested that the ageing approach used in this study could be adopted for selection of geogrids based on their long-term stiffness for structures such as reinforced embankments or mechanically stabilized earth walls that require a long service life. Moreover, results indicate that the stiffness improvement factor for the PET geogrids decreases with ageing time. On the contrary, the stiffness improvement factor of the HDPE geogrid increases with time and hypothetically might keep increasing followed by a sudden drop to zero at full degradation of the geogrid.
{"title":"Effect of oxidative ageing on stiffness improvement factor for HDPE and PET geogrids","authors":"M. S. Morsy, A. M. Elhanafy, S. S. Fathelbab, S. M. Ahmed","doi":"10.1680/jgein.23.00089","DOIUrl":"https://doi.org/10.1680/jgein.23.00089","url":null,"abstract":"The effect of thermal-oxidative ageing on the in-isolation and in-soil stiffness is investigated for two high-density polyethylene (HDPE) and two polyester (PET) geogrids when incubated in an oven at 90<sup>o</sup>C. It is shown that the in-isolation and in-soil stiffness of three out of the four geogrids decreased during the 4-month ageing time with a faster degradation of the two PET geogrids. In contrast, one of the HDPE geogrids examined with thicker rib shows slower degradation compared to the PET counterparts. It is also shown that a geogrid might have a higher unaged stiffness, but less aged stiffness compared to another geogrid made of the same polymer type. It is suggested that the ageing approach used in this study could be adopted for selection of geogrids based on their long-term stiffness for structures such as reinforced embankments or mechanically stabilized earth walls that require a long service life. Moreover, results indicate that the stiffness improvement factor for the PET geogrids decreases with ageing time. On the contrary, the stiffness improvement factor of the HDPE geogrid increases with time and hypothetically might keep increasing followed by a sudden drop to zero at full degradation of the geogrid.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2023-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138515185","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}
In order to efficiently estimate the properties of landfill composite liners, equivalent analytical models based on time moment are proposed. The service performance of geomembrane layer (GMBL)/geosynthetic clay layer (GCL)/attenuation layer (AL) and GMBL/compacted clay layer (CCL)/AL are equivalent analyzed. The equivalent analysis and quantitative correlation of contaminants at the bottom of GMBL/GCL/AL and GMBL/CCL/AL are considered according to relative concentration (CN), instantaneous flux (JI) and accumulative flux (JA). We showed that CN is the most conservative equivalent index. The thickness equivalent relation of AL for different composite liners is consequently obtained using the pure diffusion equivalent model and the advection-diffusion equivalent model, respectively. It is found that the pure diffusion thickness equivalent relationship was a simplified linear correlation and time independent. The quadratic polynomial equivalent equations of AL thickness for different service time are obtained by group method of data handling approach (GMDH). The results show that GCL composite liner has better environmental protection performance than CCL composite liner. When the thickness of GMBL/CCL/AL composite liner is fixed, the corresponding equivalent thickness of AL in GMBL/GCL/AL composite liner decreased with the rise of leachate head and wrinkle length for the same value of CN.
{"title":"Equivalent analytical models for assessment of landfill composite liners","authors":"H. Xie, W. Xu, L. Wang, H. Yan, J. Wu","doi":"10.1680/jgein.23.00117","DOIUrl":"https://doi.org/10.1680/jgein.23.00117","url":null,"abstract":"In order to efficiently estimate the properties of landfill composite liners, equivalent analytical models based on time moment are proposed. The service performance of geomembrane layer (GMBL)/geosynthetic clay layer (GCL)/attenuation layer (AL) and GMBL/compacted clay layer (CCL)/AL are equivalent analyzed. The equivalent analysis and quantitative correlation of contaminants at the bottom of GMBL/GCL/AL and GMBL/CCL/AL are considered according to relative concentration (<i>C<sub>N</sub></i>), instantaneous flux (<i>J<sub>I</sub></i>) and accumulative flux (<i>J<sub>A</sub></i>). We showed that <i>C<sub>N</sub></i> is the most conservative equivalent index. The thickness equivalent relation of AL for different composite liners is consequently obtained using the pure diffusion equivalent model and the advection-diffusion equivalent model, respectively. It is found that the pure diffusion thickness equivalent relationship was a simplified linear correlation and time independent. The quadratic polynomial equivalent equations of AL thickness for different service time are obtained by group method of data handling approach (GMDH). The results show that GCL composite liner has better environmental protection performance than CCL composite liner. When the thickness of GMBL/CCL/AL composite liner is fixed, the corresponding equivalent thickness of AL in GMBL/GCL/AL composite liner decreased with the rise of leachate head and wrinkle length for the same value of <i>C<sub>N</sub></i>.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138515176","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}
M. Fatehi, B. Yaghoobi, M. Payan, I. Hosseinpour, R. Jamshidi Chenari
The current study investigates the ultimate bearing capacity of obliquely/eccentrically loaded shallow strip foundations resting on a geogrid-reinforced granular fill with limited thickness over a very soft to soft clay layer. To this end, the lower bound theorems of the finite element limit analysis (FELA) and second-order cone programming (SOCP) are effectively exploited to simulate the underlying clay deposit, geogrid layer, and granular fill along with the inclined/eccentric loading exerted on the overlying footing. The accuracy of the adopted formulations was rigorously examined through several comparisons with the results of a well-established analytical approach in the literature. A comprehensive parametric study is then conducted to properly examine the influences of the geosynthetic layer characteristics and soft clay properties on the overall bearing capacity and failure envelope of the strip footing subjected to wide ranges of inclined and eccentric combined loadings. The results show that placement of a geogrid-reinforced granular fill layer over the soft clayey soil significantly increases the bearing capacity of the shallow foundation. The ultimate tensile strength of the reinforcement layer and the cohesion of the underlying very soft to soft clay deposit were also observed to have considerable effects on the size of failure envelopes.
{"title":"Combined bearing capacity of footings on geogrid-reinforced granular fill over soft clay","authors":"M. Fatehi, B. Yaghoobi, M. Payan, I. Hosseinpour, R. Jamshidi Chenari","doi":"10.1680/jgein.23.00049","DOIUrl":"https://doi.org/10.1680/jgein.23.00049","url":null,"abstract":"The current study investigates the ultimate bearing capacity of obliquely/eccentrically loaded shallow strip foundations resting on a geogrid-reinforced granular fill with limited thickness over a very soft to soft clay layer. To this end, the lower bound theorems of the finite element limit analysis (FELA) and second-order cone programming (SOCP) are effectively exploited to simulate the underlying clay deposit, geogrid layer, and granular fill along with the inclined/eccentric loading exerted on the overlying footing. The accuracy of the adopted formulations was rigorously examined through several comparisons with the results of a well-established analytical approach in the literature. A comprehensive parametric study is then conducted to properly examine the influences of the geosynthetic layer characteristics and soft clay properties on the overall bearing capacity and failure envelope of the strip footing subjected to wide ranges of inclined and eccentric combined loadings. The results show that placement of a geogrid-reinforced granular fill layer over the soft clayey soil significantly increases the bearing capacity of the shallow foundation. The ultimate tensile strength of the reinforcement layer and the cohesion of the underlying very soft to soft clay deposit were also observed to have considerable effects on the size of failure envelopes.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2023-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138515174","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}
Three comparative treatment plans are used in red clay subgrade, in order to research the effect of red clay subgrade reinforced with geocell. Multiple subgrade test methods including Benkelman beam, portable falling weight deflectometer, dynamic cone penetrometer and standard vehicle load tests are adopted in the field tests. Test results show that the application of geocell in red clay subgrade can enhance the overall stiffness and strength of the subgrade. The mechanism of geocell in the subgrade is studied. Geocell can provid added confinement on the surbgrade soil.Compared with the red clay subgrade without geocell-reinforcement, the rebound modulus of the red clay subgrade reinforced with 0.1-m-height geocell and 0.05-m-height geocell show a 65% and 33% increase, the dynamic modulus increase by 69% and 38% and the penetrations decrease by 51.7% and 40.4%, respectively. A hard shell layer is formed in the subgrade, after the surbgrade is reinforced with the geocell. Geocell reinforced layer plays mainly the role of stress diffusion. It not only can reduce the additional stress in the subgrade, but also can diminish the influence depth of the vehicle load.
{"title":"Study on performance of geocell-reinforced red clay subgrade","authors":"X. W. Luo, Z. Lu, J. B. Zhang, H. L. Yao","doi":"10.1680/jgein.23.00068","DOIUrl":"https://doi.org/10.1680/jgein.23.00068","url":null,"abstract":"Three comparative treatment plans are used in red clay subgrade, in order to research the effect of red clay subgrade reinforced with geocell. Multiple subgrade test methods including Benkelman beam, portable falling weight deflectometer, dynamic cone penetrometer and standard vehicle load tests are adopted in the field tests. Test results show that the application of geocell in red clay subgrade can enhance the overall stiffness and strength of the subgrade. The mechanism of geocell in the subgrade is studied. Geocell can provid added confinement on the surbgrade soil.Compared with the red clay subgrade without geocell-reinforcement, the rebound modulus of the red clay subgrade reinforced with 0.1-m-height geocell and 0.05-m-height geocell show a 65% and 33% increase, the dynamic modulus increase by 69% and 38% and the penetrations decrease by 51.7% and 40.4%, respectively. A hard shell layer is formed in the subgrade, after the surbgrade is reinforced with the geocell. Geocell reinforced layer plays mainly the role of stress diffusion. It not only can reduce the additional stress in the subgrade, but also can diminish the influence depth of the vehicle load.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2023-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138515175","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}
Y. Rao, Z. Liu, G. Ding, J. Wang, H. Wang, X. Wu, Z. Gao
Geosynthetics are widely used in soil reinforcement engineering, where the failure modes of geosynthetics are typically pullout modes. However, current research on monitoring the pullout damage experienced by reinforced soil is limited. Accordingly, this study tested the stress variation laws and signal output characteristics of a sensor-enabled piezoelectric geobelt (SPGB) that can capture the tensile vibration signals of reinforced soil under various tensile failure conditions. We observed that the SPGB captures the response signals under different soil environments, confining pressures, and shear rates. During the pullout friction process, a spike is generated, and the displacement corresponding to the position of the spike will increase with the increase of the pullout friction rate. In the clay environment, the spike voltage is related to the confining pressure, while in the sand environment, there is no obvious relationship between the spike voltage and the confining pressure. In the gravel environment, the output voltage of SPGB fluctuates greatly, due to the embedment of gravel particles, and many negative voltages with large amplitude appeared. This study verified the promising application potential of the SPGB for the integration of soil reinforcement and monitoring, which is significant for further application of SPGB in engineering.
{"title":"Response of sensor-enabled piezoelectric geobelt reinforced soil pullout friction signals","authors":"Y. Rao, Z. Liu, G. Ding, J. Wang, H. Wang, X. Wu, Z. Gao","doi":"10.1680/jgein.23.00108","DOIUrl":"https://doi.org/10.1680/jgein.23.00108","url":null,"abstract":"Geosynthetics are widely used in soil reinforcement engineering, where the failure modes of geosynthetics are typically pullout modes. However, current research on monitoring the pullout damage experienced by reinforced soil is limited. Accordingly, this study tested the stress variation laws and signal output characteristics of a sensor-enabled piezoelectric geobelt (SPGB) that can capture the tensile vibration signals of reinforced soil under various tensile failure conditions. We observed that the SPGB captures the response signals under different soil environments, confining pressures, and shear rates. During the pullout friction process, a spike is generated, and the displacement corresponding to the position of the spike will increase with the increase of the pullout friction rate. In the clay environment, the spike voltage is related to the confining pressure, while in the sand environment, there is no obvious relationship between the spike voltage and the confining pressure. In the gravel environment, the output voltage of SPGB fluctuates greatly, due to the embedment of gravel particles, and many negative voltages with large amplitude appeared. This study verified the promising application potential of the SPGB for the integration of soil reinforcement and monitoring, which is significant for further application of SPGB in engineering.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2023-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138515180","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}
Geomembrane (GM) is a kind of cost-efficient material for pollutant barrier in landfills, while defects can occur during the installation or service periods, resulting in a mixed-type boundary condition (MTBC) at the top surface of underlying soil layer (SL). In this study, a novel boundary transform method is employed to handle the MTBC problem of axisymmetric transport of organic contaminant through defected GM, and a semi-analytical solution is derived to evaluate the concentration profiles in the spatiotemporal domain. The proposed solution is in the cylindrical coordinates that can incorporate the diffusion and dispersion processes, as well as the concentration condition in the GM defect. The discretization method, integral transforms and corresponding inverse transforms are applied to obtain the semi-analytical solution, which is demonstrated effective compared to the numerical results. The model is applied to predict the migration characteristics of organic contaminant in several cases, followed by discussions to evaluate the influencing roles of defect rate, anisotropic coefficient, and segment number. Results indicate that the existence of defects substantially reduces the barrier capacity of the GM layer, and the contaminant migration time varies in several orders of magnitude for different MTBCs.
{"title":"Semi-analytical model for axisymmetric transport of contaminant through flawed geomembrane","authors":"T. Li, D. Sun, P. Ni, Z. Chen, L. Wang","doi":"10.1680/jgein.23.00091","DOIUrl":"https://doi.org/10.1680/jgein.23.00091","url":null,"abstract":"Geomembrane (GM) is a kind of cost-efficient material for pollutant barrier in landfills, while defects can occur during the installation or service periods, resulting in a mixed-type boundary condition (MTBC) at the top surface of underlying soil layer (SL). In this study, a novel boundary transform method is employed to handle the MTBC problem of axisymmetric transport of organic contaminant through defected GM, and a semi-analytical solution is derived to evaluate the concentration profiles in the spatiotemporal domain. The proposed solution is in the cylindrical coordinates that can incorporate the diffusion and dispersion processes, as well as the concentration condition in the GM defect. The discretization method, integral transforms and corresponding inverse transforms are applied to obtain the semi-analytical solution, which is demonstrated effective compared to the numerical results. The model is applied to predict the migration characteristics of organic contaminant in several cases, followed by discussions to evaluate the influencing roles of defect rate, anisotropic coefficient, and segment number. Results indicate that the existence of defects substantially reduces the barrier capacity of the GM layer, and the contaminant migration time varies in several orders of magnitude for different MTBCs.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138515182","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}
Field observations and centrifuge tests indicate that progressive column bending failure accompanies most instabilities of rigid column-supported and geosynthetic-reinforced (RCGR) embankments. However, recognized guidelines specifically for evaluating the overall stability of such systems featuring bending failure remain limited. This study presents a general methodology to calculate the factor of safety (FS) for RCGR embankments using the limit equilibrium method. The focus is on deep-seated slope failures, wherein rigid columns progressively fracture due to subsoil overstressing. The Concentric Arches model, along with tensioned geosynthetic analysis, informs the determination of vertical and horizontal loads on the column heads. The column's resisting moment stems from its flexural and compression resistance. A mobilization factor for the net thrust on each column is defined to capture the progressive failure. The methodology involves an iterative computational procedure to identify the critical slip surface and the FS utilising Fellenius’ method. The solution is validated against three case studies, including both centrifuge models and field tests, as well as finite element analysis. The results indicate that the soil mass contributes the most to resisting sliding and overall stability, followed by the columns and geosynthetics. In addition, axial force mainly provides the resisting moment of columns.
{"title":"Evaluating stability of rigid column-supported and geosynthetic-reinforced embankments","authors":"H. Liu, Q. Luo, M. H. El Naggar, K. Liu, T. Wang","doi":"10.1680/jgein.23.00070","DOIUrl":"https://doi.org/10.1680/jgein.23.00070","url":null,"abstract":"Field observations and centrifuge tests indicate that progressive column bending failure accompanies most instabilities of rigid column-supported and geosynthetic-reinforced (RCGR) embankments. However, recognized guidelines specifically for evaluating the overall stability of such systems featuring bending failure remain limited. This study presents a general methodology to calculate the factor of safety (<i>FS</i>) for RCGR embankments using the limit equilibrium method. The focus is on deep-seated slope failures, wherein rigid columns progressively fracture due to subsoil overstressing. The Concentric Arches model, along with tensioned geosynthetic analysis, informs the determination of vertical and horizontal loads on the column heads. The column's resisting moment stems from its flexural and compression resistance. A mobilization factor for the net thrust on each column is defined to capture the progressive failure. The methodology involves an iterative computational procedure to identify the critical slip surface and the <i>FS</i> utilising Fellenius’ method. The solution is validated against three case studies, including both centrifuge models and field tests, as well as finite element analysis. The results indicate that the soil mass contributes the most to resisting sliding and overall stability, followed by the columns and geosynthetics. In addition, axial force mainly provides the resisting moment of columns.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138515181","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 residual interface strength is mobilized along sideslopes of geosynthetic lined areas, such as landfill sideslope. Unfortunately, only a large displacement (LD) interface strength is measured in frequently used direct shear tests, which overpredicts the residual interface strength by about 40% because of limited continuous shear displacement and new geomembrane being introduced during the test. Commercial laboratories usually conduct direct shear tests in accordance with ASTM D5321 or D6243, which can only measure the LD interface strength. This paper suggests a method to estimate the residual interface strength from direct shear test results, which provides a better estimate of field interface strengths. The shear stress-displacement relationship from ring shear tests fits a power function, which can be used to extrapolate direct shear test results to a residual strength. This paper shows the power function can predict reasonable residual interface strengths from the shear stress-displacement relationship measured in direct shear tests. This method allows people to estimate the residual strength data when only direct shear test results are available and prevents overprediction of the Factor of Safety (FoS) during slope stability evaluations.
{"title":"Extrapolating residual GMX/GDC interface strength from direct shear tests","authors":"J. Lin, T. D. Stark, A. Idries","doi":"10.1680/jgein.23.00111","DOIUrl":"https://doi.org/10.1680/jgein.23.00111","url":null,"abstract":"The residual interface strength is mobilized along sideslopes of geosynthetic lined areas, such as landfill sideslope. Unfortunately, only a large displacement (LD) interface strength is measured in frequently used direct shear tests, which overpredicts the residual interface strength by about 40% because of limited continuous shear displacement and new geomembrane being introduced during the test. Commercial laboratories usually conduct direct shear tests in accordance with ASTM D5321 or D6243, which can only measure the LD interface strength. This paper suggests a method to estimate the residual interface strength from direct shear test results, which provides a better estimate of field interface strengths. The shear stress-displacement relationship from ring shear tests fits a power function, which can be used to extrapolate direct shear test results to a residual strength. This paper shows the power function can predict reasonable residual interface strengths from the shear stress-displacement relationship measured in direct shear tests. This method allows people to estimate the residual strength data when only direct shear test results are available and prevents overprediction of the Factor of Safety (FoS) during slope stability evaluations.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138515170","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}
B. Fang, S. Liu, Y. Lu, S. Chen, Y. Zhang, C. Zhang, C. Zhang
Soilbag cushion is one of the promising base isolation methods to reduce seismic energy transfer from ground to building structure. In this study, a series of shaking table tests were conducted comparatively on foundation models with soilbag cushion and sand cushion to evaluate their dynamic performance. The test results indicate that soilbag cushion could significantly reduce acceleration response and accumulated settlement compared to sand cushion. And the relatively smaller amplitude of dynamic lateral earth pressure measured on contact surface of soilbags within soilbag cushion also indicates its stability during oscillation. The advantages of soilbag cushion for energy dissipation and damping are more easily highlighted under the condition of high-acceleration, high-frequency or high uniformly distributed load. The dynamic performance of soilbag cushion is dependent on embedded depth and thickness. It is most effective for soilbag cushion to be arranged near the rigid footing of building structures; it is suggested that the number of layers of soilbag cushion be controlled on the premise of the designed ratio of the thickness to the width of soilbag cushion ranging from 0.125 to 0.4 for low- or middle-rise masonry buildings in practical engineering.
{"title":"Investigation on dynamic performance of soilbag cushion using shaking table tests","authors":"B. Fang, S. Liu, Y. Lu, S. Chen, Y. Zhang, C. Zhang, C. Zhang","doi":"10.1680/jgein.23.00074","DOIUrl":"https://doi.org/10.1680/jgein.23.00074","url":null,"abstract":"Soilbag cushion is one of the promising base isolation methods to reduce seismic energy transfer from ground to building structure. In this study, a series of shaking table tests were conducted comparatively on foundation models with soilbag cushion and sand cushion to evaluate their dynamic performance. The test results indicate that soilbag cushion could significantly reduce acceleration response and accumulated settlement compared to sand cushion. And the relatively smaller amplitude of dynamic lateral earth pressure measured on contact surface of soilbags within soilbag cushion also indicates its stability during oscillation. The advantages of soilbag cushion for energy dissipation and damping are more easily highlighted under the condition of high-acceleration, high-frequency or high uniformly distributed load. The dynamic performance of soilbag cushion is dependent on embedded depth and thickness. It is most effective for soilbag cushion to be arranged near the rigid footing of building structures; it is suggested that the number of layers of soilbag cushion be controlled on the premise of the designed ratio of the thickness to the width of soilbag cushion ranging from 0.125 to 0.4 for low- or middle-rise masonry buildings in practical engineering.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135190996","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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