Fibre-reinforced composite paste backfill (F-CPB; a mixture of tailings, fibre, cement, and water) is exposed to non-isothermal curing environments in the field. But, no investigations have been conducted on the impact of non-isothermal curing environments on the F-CPB compressive strength, shear characteristics and stress-strain behaviour, although these are important design parameters for F-CPB structures. Therefore, a series of mechanical and microstructural tests were performed on samples with and without fibres exposed to isothermal and non-isothermal conditions. It was found that the non-isothermal curing condition substantially enhances the F-CPB compressive strength and the strength gain ratio. The shear strength, cohesion and internal friction angle of the F-CPB samples cured under non-isothermal conditions were higher than those cured under isothermal conditions. These impacts of non-isothermal curing on the compressive and shear characteristcis of F-CPBs are related to the temperature induced change in the microstructure of these samples. The F-CPBs cured under non-isothermal conditions had more hydration products than those cured under isothermal conditions. Moreover, the MIP tests shown that the F-CPBs subjected to non-isothermal conditions had a finer pore structure than those exposed to isothermal conditions, which contributed to an enhancement of the mechanical characteristics of the F-CPBs subjected to non-isothermal curing.
{"title":"Compressive and shear response of fibre-reinforced backfill: Impact of field temperatures","authors":"X. Tian, M. Fall","doi":"10.1680/jgein.22.00310","DOIUrl":"https://doi.org/10.1680/jgein.22.00310","url":null,"abstract":"Fibre-reinforced composite paste backfill (F-CPB; a mixture of tailings, fibre, cement, and water) is exposed to non-isothermal curing environments in the field. But, no investigations have been conducted on the impact of non-isothermal curing environments on the F-CPB compressive strength, shear characteristics and stress-strain behaviour, although these are important design parameters for F-CPB structures. Therefore, a series of mechanical and microstructural tests were performed on samples with and without fibres exposed to isothermal and non-isothermal conditions. It was found that the non-isothermal curing condition substantially enhances the F-CPB compressive strength and the strength gain ratio. The shear strength, cohesion and internal friction angle of the F-CPB samples cured under non-isothermal conditions were higher than those cured under isothermal conditions. These impacts of non-isothermal curing on the compressive and shear characteristcis of F-CPBs are related to the temperature induced change in the microstructure of these samples. The F-CPBs cured under non-isothermal conditions had more hydration products than those cured under isothermal conditions. Moreover, the MIP tests shown that the F-CPBs subjected to non-isothermal conditions had a finer pore structure than those exposed to isothermal conditions, which contributed to an enhancement of the mechanical characteristics of the F-CPBs subjected to non-isothermal curing.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2023-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48349155","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 practice, little attention has been paid directly to freeze-thaw (FT) cycles during the design and analysis of geogrid-reinforced soil (GRS) walls due to lacking relevant literature. This study investigates the pavement vertical deformation (s), panel lateral deformation (d), lateral earth pressure (σh), and geogrid strain (ε) of a field GRS wall using an ABAQUS-based numerical model considering variations of the recorded five-year ambient temperature (TR). Numerical results show that the s distribution follows a convex shape instead of the initial concave shape after FT cycles and can be divided into high, transition, and stable deformation zones. FT action alters both location and amplitude of the maximum d within the first two cycles, making the d distribution evolve from a J-shaped curve into an S-shaped one. During freezing, the developments of s and d are coordinated and can be described using a unified model; σh is larger than the Rankine active earth pressure; ε state depends on the interplay of two factors resulting from d and frost heave force. Furthermore, the hysteresis of s, d,σh, and ε with TR was discussed and several beneficial suggestions were proposed for GRS walls to avoid such FT destruction.
{"title":"Numerical simulation on the performance of GRS walls with freeze-thaw cycles consideration","authors":"Lu-qiang Ding, F. Cui, C. Xiao","doi":"10.1680/jgein.22.00368","DOIUrl":"https://doi.org/10.1680/jgein.22.00368","url":null,"abstract":"In practice, little attention has been paid directly to freeze-thaw (FT) cycles during the design and analysis of geogrid-reinforced soil (GRS) walls due to lacking relevant literature. This study investigates the pavement vertical deformation (s), panel lateral deformation (d), lateral earth pressure (σh), and geogrid strain (ε) of a field GRS wall using an ABAQUS-based numerical model considering variations of the recorded five-year ambient temperature (TR). Numerical results show that the s distribution follows a convex shape instead of the initial concave shape after FT cycles and can be divided into high, transition, and stable deformation zones. FT action alters both location and amplitude of the maximum d within the first two cycles, making the d distribution evolve from a J-shaped curve into an S-shaped one. During freezing, the developments of s and d are coordinated and can be described using a unified model; σh is larger than the Rankine active earth pressure; ε state depends on the interplay of two factors resulting from d and frost heave force. Furthermore, the hysteresis of s, d,σh, and ε with TR was discussed and several beneficial suggestions were proposed for GRS walls to avoid such FT destruction.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2023-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42591660","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}
Low-permeability liners are required at the base of municipal solid waste (MSW) landfills to minimize leachate leakage and contaminant migration into groundwater. This paper uses a two-dimensional coupled groundwater flow and contaminant transport model to examine the performance of three types of low-permeability liners specified by the current Chinese landfill standard: (1) a compacted clay liner (CCL), (2) a geomembrane (GMB) overlying a CCL, and (3) a GMB overlying a geosynthetic clay liner (GCL) on a CCL. The model simulates leachate leaking and contaminant migrating over the entire base of the landfill for the CCL and through the holed GMB wrinkles for the GMB composite liners. The performance of each type of low-permeability liners was evaluated and compared in terms of leakage rate and peak impact of chloride on the aquifer. Based on liner cases and conditions examined in this paper, the results show that the three types of low-permeability liners are not equivalent for minimizing the leakage rate and chloride impact on the aquifer. The GMB+GCL+CCL performs the best among the three low-permeability liners, and is effective for limiting the peak chloride impact on the aquifer below the acceptable level in drinking water.
{"title":"Performance of landfill low-permeability liners for minimizing groundwater contamination","authors":"W. Hu, Y. Yu, R. Rowe","doi":"10.1680/jgein.22.00340","DOIUrl":"https://doi.org/10.1680/jgein.22.00340","url":null,"abstract":"Low-permeability liners are required at the base of municipal solid waste (MSW) landfills to minimize leachate leakage and contaminant migration into groundwater. This paper uses a two-dimensional coupled groundwater flow and contaminant transport model to examine the performance of three types of low-permeability liners specified by the current Chinese landfill standard: (1) a compacted clay liner (CCL), (2) a geomembrane (GMB) overlying a CCL, and (3) a GMB overlying a geosynthetic clay liner (GCL) on a CCL. The model simulates leachate leaking and contaminant migrating over the entire base of the landfill for the CCL and through the holed GMB wrinkles for the GMB composite liners. The performance of each type of low-permeability liners was evaluated and compared in terms of leakage rate and peak impact of chloride on the aquifer. Based on liner cases and conditions examined in this paper, the results show that the three types of low-permeability liners are not equivalent for minimizing the leakage rate and chloride impact on the aquifer. The GMB+GCL+CCL performs the best among the three low-permeability liners, and is effective for limiting the peak chloride impact on the aquifer below the acceptable level in drinking water.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2022-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44207347","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}
Freeze-thaw (F-T) cycles are a major cause of pavement distress in seasonal frost regions, and the presence of fines in bases can accelerate the pavement degradation induced by cyclic freeze and thaw. Among countermeasures used to mitigate the F-T induced damages in pavements, geocell-reinforced bases can be an effective solution in mitigating F-T damages to cold region roads. However, there is almost no research dedicated to understanding the potential benefit of geocells and the underlying mechanisms in this regard. This study employed a custom-made model test device to investigate the F-T performance of geocell-reinforced sands considering different fines contents. The experimental results showed that the increase in fines content substantially increased the peak heave and thaw settlement and decreased the stiffness and ultimate bearing pressure. The application of geocells reduced the peak heave and thaw settlement by 11%- 18% and 22%- 35%, respectively, but this benefit was negligible at high kaolin content (12%). The use of geocells increased the stiffness and ultimate bearing pressure by about 43%- 90% and 41%- 73%, respectively, after five F-T cycles. The findings of this study are relevant to the design of geocell-reinforced bases under F-T cycles and advance the understanding of the underlying mechanisms.
{"title":"Freeze-thaw behavior of geocell-reinforced bases considering different fines contents","authors":"M. Huang, C. Lin, S. Pokharel","doi":"10.1680/jgein.22.00298","DOIUrl":"https://doi.org/10.1680/jgein.22.00298","url":null,"abstract":"Freeze-thaw (F-T) cycles are a major cause of pavement distress in seasonal frost regions, and the presence of fines in bases can accelerate the pavement degradation induced by cyclic freeze and thaw. Among countermeasures used to mitigate the F-T induced damages in pavements, geocell-reinforced bases can be an effective solution in mitigating F-T damages to cold region roads. However, there is almost no research dedicated to understanding the potential benefit of geocells and the underlying mechanisms in this regard. This study employed a custom-made model test device to investigate the F-T performance of geocell-reinforced sands considering different fines contents. The experimental results showed that the increase in fines content substantially increased the peak heave and thaw settlement and decreased the stiffness and ultimate bearing pressure. The application of geocells reduced the peak heave and thaw settlement by 11%- 18% and 22%- 35%, respectively, but this benefit was negligible at high kaolin content (12%). The use of geocells increased the stiffness and ultimate bearing pressure by about 43%- 90% and 41%- 73%, respectively, after five F-T cycles. The findings of this study are relevant to the design of geocell-reinforced bases under F-T cycles and advance the understanding of the underlying mechanisms.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2022-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45404779","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}
This study evaluates the performance of two-tiered geogrid-reinforced soil (GRS) walls subjected to traffic cyclic loading considering several influence factors. These factors herein include the offset distance (D) of walls, the number (N), amplitude (Pmax), and frequency (f) of applied cyclic loading. Seven GRS walls with a reduced-scale of 1:3 were prepared in the laboratory and employed to investigate their (i) vertical foundation pressures during construction, (ii) load-induced settlements, (iii) facing lateral displacements, (iv) vertical and horizontal earth pressures, and (v) geogrid strains under the action of cyclic loading. Experimental results demonstrate that GRS walls constructed in tiered configurations can effectively reduce vertical foundation pressures. The increasing D, as well as the decreasing N and Pmax, introduces a reduction to the above five mechanical and deformation properties. However, increasing f results in the decrease of wall settlements and facing lateral displacements, and in the increase of others. Performance of several empirical equations for predicting the vertical foundation pressures, location of maximum geogrid strains, and failure surfaces inside walls was examined using the experimental data obtained in this study. Comparisons also were performed to describe the deformation and failure surface modes of the walls after loading.
{"title":"Determining performance of two-tiered GRS walls subjected to traffic cyclic loading","authors":"L. Ding, J. Liu, T. Zhou, C. Xiao, H. Li","doi":"10.1680/jgein.22.00260","DOIUrl":"https://doi.org/10.1680/jgein.22.00260","url":null,"abstract":"This study evaluates the performance of two-tiered geogrid-reinforced soil (GRS) walls subjected to traffic cyclic loading considering several influence factors. These factors herein include the offset distance (D) of walls, the number (N), amplitude (Pmax), and frequency (f) of applied cyclic loading. Seven GRS walls with a reduced-scale of 1:3 were prepared in the laboratory and employed to investigate their (i) vertical foundation pressures during construction, (ii) load-induced settlements, (iii) facing lateral displacements, (iv) vertical and horizontal earth pressures, and (v) geogrid strains under the action of cyclic loading. Experimental results demonstrate that GRS walls constructed in tiered configurations can effectively reduce vertical foundation pressures. The increasing D, as well as the decreasing N and Pmax, introduces a reduction to the above five mechanical and deformation properties. However, increasing f results in the decrease of wall settlements and facing lateral displacements, and in the increase of others. Performance of several empirical equations for predicting the vertical foundation pressures, location of maximum geogrid strains, and failure surfaces inside walls was examined using the experimental data obtained in this study. Comparisons also were performed to describe the deformation and failure surface modes of the walls after loading.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2022-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42842515","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. N. Moghaddas Tafreshi, S. Kheiri, M. Azizian, A. R. Dawson
This paper reports on a series of static and cyclic plate loading tests performed on a weak unreinforced sand bed in a test pit. The weak sand was covered by a 160 mm thick layer comprised of one of three compacted soil types which was either unreinforced or geocell-reinforced. The purpose was to investigate the effects of soil density and grain size as filler materials for the covering layer. The three covering soils were granular with average particle sizes of 2.2 (Soil 1), 6.14 (Soil 2), and 8.47 (Soil 3) mm. Under static loading, the bearing pressure increased on average 23% when the average grain size of the upper, unreinforced, soil layer changed from 2.20 mm to 8.47 mm. The improvement in bearing pressure was about 37% due to the use of a soil-filled geocell but, unlike the unreinforced situation, employing larger soil grains to fill the geocell pockets didn't show significant further improvement. For cyclic loading tests, the maximum settlement reduction by employing a geocell layer was about 50% for Soil 1. Whether loaded statically or cyclically, increasing soil density likely would be more efficient for improving geocell performance than by employing a soil having larger particle sizes.
{"title":"Geocell-reinforced bed under static and cyclic loads: Effect of soil density and grain size","authors":"S. N. Moghaddas Tafreshi, S. Kheiri, M. Azizian, A. R. Dawson","doi":"10.1680/jgein.22.00259","DOIUrl":"https://doi.org/10.1680/jgein.22.00259","url":null,"abstract":"This paper reports on a series of static and cyclic plate loading tests performed on a weak unreinforced sand bed in a test pit. The weak sand was covered by a 160 mm thick layer comprised of one of three compacted soil types which was either unreinforced or geocell-reinforced. The purpose was to investigate the effects of soil density and grain size as filler materials for the covering layer. The three covering soils were granular with average particle sizes of 2.2 (Soil 1), 6.14 (Soil 2), and 8.47 (Soil 3) mm. Under static loading, the bearing pressure increased on average 23% when the average grain size of the upper, unreinforced, soil layer changed from 2.20 mm to 8.47 mm. The improvement in bearing pressure was about 37% due to the use of a soil-filled geocell but, unlike the unreinforced situation, employing larger soil grains to fill the geocell pockets didn't show significant further improvement. For cyclic loading tests, the maximum settlement reduction by employing a geocell layer was about 50% for Soil 1. Whether loaded statically or cyclically, increasing soil density likely would be more efficient for improving geocell performance than by employing a soil having larger particle sizes.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2022-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43548853","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}
Interface shear characteristics have an important impact on the stability of geosynthetically reinforced soil structures. The shear characteristics of three-dimensional geogrid–sand interfaces were investigated using large-scale direct shear tests and the discrete element method. Geogrids were manufactured by 3D printing. The effect of a mesh pattern and transverse-rib thickness on the stress–displacement relationship, strength parameters, coordination number, and porosity distribution were evaluated. The results showed that the mesh pattern and transverse-rib thickness have an impact on the interface shear characteristics. The peak and residual interface shear strength of modified geogrid mesh pattern exceeded that of biaxial geogrids. The average coordination numbers of the modified geogrid mesh pattern were greater than those of the biaxial geogrid. The variability of particle compactness, as characterised by the porosity distribution, shows how the modified mesh pattern increases the interface shear strength. The interface shear strength of the geogrid-sand interface was improved by thickening the transverse ribs of the modified geogrid mesh pattern.
{"title":"Test and DEM investigation on shear behaviour of three-dimensional geogrid–sand interface","authors":"W. Zeng, F. Liu, X. Zhu, J. He, J. Wang","doi":"10.1680/jgein.22.00289","DOIUrl":"https://doi.org/10.1680/jgein.22.00289","url":null,"abstract":"Interface shear characteristics have an important impact on the stability of geosynthetically reinforced soil structures. The shear characteristics of three-dimensional geogrid–sand interfaces were investigated using large-scale direct shear tests and the discrete element method. Geogrids were manufactured by 3D printing. The effect of a mesh pattern and transverse-rib thickness on the stress–displacement relationship, strength parameters, coordination number, and porosity distribution were evaluated. The results showed that the mesh pattern and transverse-rib thickness have an impact on the interface shear characteristics. The peak and residual interface shear strength of modified geogrid mesh pattern exceeded that of biaxial geogrids. The average coordination numbers of the modified geogrid mesh pattern were greater than those of the biaxial geogrid. The variability of particle compactness, as characterised by the porosity distribution, shows how the modified mesh pattern increases the interface shear strength. The interface shear strength of the geogrid-sand interface was improved by thickening the transverse ribs of the modified geogrid mesh pattern.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2022-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44196287","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}
Inadequate shear strength mobilization at the interfaces results in translational failures in Geosynthetic Clay Liners (GCL). Periodic addition of solid waste into the landfill causes additional normal and shear stresses in GCLs. The mechanical response of GCLs is highly time dependent and over the time, the quality and strength of fibres of GCL deteriorate. Hence the interface shear resistance reduces under the application of repeated shear cycles. To simulate these conditions, a repeated interface shearing test was conceptualized in this study. A natural river sand and a manufactured sand of identical gradation were used in experiments to understand the effects of particle shape on interface shear strength variation under repeated shearing. Each GCL-sand interface was subjected to eight cycles of shearing in dry and hydrated conditions under three different static normal stresses. Results showed that the variation of the peak interface shear stress has different phases, governed by different mechanisms. Digital image analysis of tested GCL surfaces after each shearing cycle provided important clues for this response. Entrapment of sand particles into GCL surface is beneficial initially because of increased friction at the interface and this benefit is more pronounced in case of manufactured sand, due to the irregular shape of particles. After a few shearing cycles, the fibres of the GCL got ruptured due to repeated rubbing of sand particles, which reduced the shearing resistance. Quantification of sand particle entrapment and surface changes to GCL helped in understanding these micro-level interaction mechanisms.
{"title":"Digital image-based Performance evaluation of GCL-sand interfaces under repeated shearing","authors":"Anjali G. Pillai, M. Gali","doi":"10.1680/jgein.22.00352","DOIUrl":"https://doi.org/10.1680/jgein.22.00352","url":null,"abstract":"Inadequate shear strength mobilization at the interfaces results in translational failures in Geosynthetic Clay Liners (GCL). Periodic addition of solid waste into the landfill causes additional normal and shear stresses in GCLs. The mechanical response of GCLs is highly time dependent and over the time, the quality and strength of fibres of GCL deteriorate. Hence the interface shear resistance reduces under the application of repeated shear cycles. To simulate these conditions, a repeated interface shearing test was conceptualized in this study. A natural river sand and a manufactured sand of identical gradation were used in experiments to understand the effects of particle shape on interface shear strength variation under repeated shearing. Each GCL-sand interface was subjected to eight cycles of shearing in dry and hydrated conditions under three different static normal stresses. Results showed that the variation of the peak interface shear stress has different phases, governed by different mechanisms. Digital image analysis of tested GCL surfaces after each shearing cycle provided important clues for this response. Entrapment of sand particles into GCL surface is beneficial initially because of increased friction at the interface and this benefit is more pronounced in case of manufactured sand, due to the irregular shape of particles. After a few shearing cycles, the fibres of the GCL got ruptured due to repeated rubbing of sand particles, which reduced the shearing resistance. Quantification of sand particle entrapment and surface changes to GCL helped in understanding these micro-level interaction mechanisms.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2022-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43590022","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}
Sayan Mukherjee, A. K. Choudhary, G. S. Sivakumar Babu
Inclined anchors are used in civil engineering structures where the foundations are expected to resist pullout forces during their operational period. This paper presents a three-dimensional numerical analysis of inclined anchors placed in unreinforced and reinforced sand. The influence of several parameters on the response of inclined anchor plates has been investigated in this study. Results indicate that geogrid reinforcement placed on top of the anchor plate significantly influences the anchor plate's performance. The ultimate pullout capacity is found to increase with the inclination angle (varied from 30° to 60°) of the anchor plate both in unreinforced and reinforced sand. The anchor capacity is also affected by other parameters such as friction angle of sand (varied from 35° to 45°), embedment depth of the anchor plate (varied from 2 to 10) and tensile stiffness of the geogrid. Besides, the comparison between piles and anchors has been presented with the help of an illustrative example of a transmission tower foundation. The design calculations indicate that inclined anchors placed in reinforced sand can lead to economical design at shallow depth as compared to piles.
{"title":"Three-dimensional Analysis of Inclined Anchors in Reinforced Sand","authors":"Sayan Mukherjee, A. K. Choudhary, G. S. Sivakumar Babu","doi":"10.1680/jgein.22.00318","DOIUrl":"https://doi.org/10.1680/jgein.22.00318","url":null,"abstract":"Inclined anchors are used in civil engineering structures where the foundations are expected to resist pullout forces during their operational period. This paper presents a three-dimensional numerical analysis of inclined anchors placed in unreinforced and reinforced sand. The influence of several parameters on the response of inclined anchor plates has been investigated in this study. Results indicate that geogrid reinforcement placed on top of the anchor plate significantly influences the anchor plate's performance. The ultimate pullout capacity is found to increase with the inclination angle (varied from 30° to 60°) of the anchor plate both in unreinforced and reinforced sand. The anchor capacity is also affected by other parameters such as friction angle of sand (varied from 35° to 45°), embedment depth of the anchor plate (varied from 2 to 10) and tensile stiffness of the geogrid. Besides, the comparison between piles and anchors has been presented with the help of an illustrative example of a transmission tower foundation. The design calculations indicate that inclined anchors placed in reinforced sand can lead to economical design at shallow depth as compared to piles.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2022-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49057123","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}
Small- and large-scale 1g experiments were conducted to investigate the bearing capacity failure of geosynthetic-reinforced soil walls. The small-scale experiments (1/10) provided fundamental insights into the development of failure based on digital image correlation analysis. Since these tests suffered from scale effects, large-scale tests (1/1.67) were performed to quantify the ultimate load-bearing capacity of a 1.2 m high wall. A vertical load was applied on top of the structures and internal soil movements and stresses, wall deformations and reinforcement strains were measured. The experimental results revealed that the failure was initially triggered at the rear end of the bottom reinforcement. The wall rotated to the backfill and the ground surface in front of the wall was uplifted. The results confirmed the quasi-monolithic behaviour of the reinforced zone. A multi-body failure mechanism was observed below the base of the wall, consisting of an active and passive wedge connected by a transition zone. Important scaling factors were discussed using the two different scales which has shown important conclusions that are relevant for experimental studies. The analytical calculations revealed that a reduced reinforcement length needs to be considered in the analytical approach to predict a rather conservative load-bearing capacity.
{"title":"Experimental analysis of bearing capacity failure of geosynthetic-reinforced soil walls","authors":"J. Derksen, M. Ziegler, R. Fuentes","doi":"10.1680/jgein.22.00296","DOIUrl":"https://doi.org/10.1680/jgein.22.00296","url":null,"abstract":"Small- and large-scale 1g experiments were conducted to investigate the bearing capacity failure of geosynthetic-reinforced soil walls. The small-scale experiments (1/10) provided fundamental insights into the development of failure based on digital image correlation analysis. Since these tests suffered from scale effects, large-scale tests (1/1.67) were performed to quantify the ultimate load-bearing capacity of a 1.2 m high wall. A vertical load was applied on top of the structures and internal soil movements and stresses, wall deformations and reinforcement strains were measured. The experimental results revealed that the failure was initially triggered at the rear end of the bottom reinforcement. The wall rotated to the backfill and the ground surface in front of the wall was uplifted. The results confirmed the quasi-monolithic behaviour of the reinforced zone. A multi-body failure mechanism was observed below the base of the wall, consisting of an active and passive wedge connected by a transition zone. Important scaling factors were discussed using the two different scales which has shown important conclusions that are relevant for experimental studies. The analytical calculations revealed that a reduced reinforcement length needs to be considered in the analytical approach to predict a rather conservative load-bearing capacity.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2022-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44757816","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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