This paper presents the results of centrifuge model tests to investigate the deformation behavior of unreinforced and reinforced transparent soil foundations under strip loading. Digital image analysis technique was employed to obtain the soil displacement field and strain distribution of reinforcements. Two-dimensional numerical models were developed and verified using the test results. The soil was modeled as a linearly-elastic perfectly-plastic material with Mohr-Coulomb failure criterion. The reinforcement was characterized using a linearly-elastic model with considering rupture behavior. Moreover, a parametric study was conducted to investigate the load-settlement response of foundations, distribution of reinforcement tension and failure sequence of reinforcements. The experimental and numerical studies show that the results obtained from the numerical simulations are in good agreement with the results of the centrifuge model tests. The two-dimensional finite difference model developed using the user-defined functions coded into the program FLAC can better simulate the progressive failure of the reinforcement layers in the tests. The failure sequence of reinforcement layers is not affected by the modulus and internal friction angle of soils and the reinforcement length, but is closely related to the combining effect of spacing and number of reinforcement layers and the combining effect of reinforcement stiffness and strength.
{"title":"Centrifuge model and numerical studies of strip footing on reinforced transparent soils","authors":"X. Guo, J. Chen, J. Xue, Z. Zhang","doi":"10.1680/jgein.21.00120","DOIUrl":"https://doi.org/10.1680/jgein.21.00120","url":null,"abstract":"This paper presents the results of centrifuge model tests to investigate the deformation behavior of unreinforced and reinforced transparent soil foundations under strip loading. Digital image analysis technique was employed to obtain the soil displacement field and strain distribution of reinforcements. Two-dimensional numerical models were developed and verified using the test results. The soil was modeled as a linearly-elastic perfectly-plastic material with Mohr-Coulomb failure criterion. The reinforcement was characterized using a linearly-elastic model with considering rupture behavior. Moreover, a parametric study was conducted to investigate the load-settlement response of foundations, distribution of reinforcement tension and failure sequence of reinforcements. The experimental and numerical studies show that the results obtained from the numerical simulations are in good agreement with the results of the centrifuge model tests. The two-dimensional finite difference model developed using the user-defined functions coded into the program FLAC can better simulate the progressive failure of the reinforcement layers in the tests. The failure sequence of reinforcement layers is not affected by the modulus and internal friction angle of soils and the reinforcement length, but is closely related to the combining effect of spacing and number of reinforcement layers and the combining effect of reinforcement stiffness and strength.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":"1 1","pages":""},"PeriodicalIF":4.5,"publicationDate":"2022-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67480917","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 hydraulic conductivity (k) of specimens of enhanced-bentonite geosynthetic clay liners (EB-GCLs) comprising anionic polymers permeated with concentrated salt solutions, i.e., 500 mM NaCl and 167 mM CaCl2, was measured to determine the effects of polymer properties and specimen preparation method on the k and the associated roles of polymer retention and elution in dictating the measured k. The results of hydrogel formation tests illustrated that poly(acrylic acid) hydrogel was formed in solutions tested during EB-GCL hydration. A dry sprinkling method of specimen preparation resulted in low k (≤ 5.5×10−11 m/s) in multiple EB-GCLs, with a low fraction (≤ 2.5 %) of retained polymer. In contrast, polymer elution from EB-GCLs prepared using a dry mixing method resulted in interaggregate seepage and an increase in k. Higher polymer retention occurred for the wet-mixed EB-GCLs, but did not directly correlate to low k. The long-term k of the EB-GCLs is dependent on several factors, including (i) formation of hydrogel, (ii) mobilization of hydrogel into and blocking of the most conductive pores, (iii) balance of seepage forces and hydrogel crosslink bond strength, (iv) kinetics of hydrogel formation, and (v) adsorption of polymer to the surfaces of the bentonite particles or aggregates of particles.
由阴离子聚合物组成的增强膨润土土工合成粘土衬垫(EB-GCLs)试样的水导率(k)，其渗透浓度为500 mM NaCl和167 mM CaCl2，测定了聚合物性质和样品制备方法对k的影响，以及聚合物保留和洗脱在决定测量k时的相关作用。水凝胶形成测试的结果表明，聚丙烯酸水凝胶是在EB-GCL水化过程中测试的溶液中形成的。干喷法制备样品的方法导致多个eb - gcl的低k(≤5.5×10 - 11 m/s)，保留的聚合物含量低(≤2.5%)。相比之下，使用干混合方法制备的eb - gcl的聚合物洗脱导致了集束间的渗透和k的增加。湿混合eb - gcl的聚合物保留率更高，但与低k没有直接关系。eb - gcl的长期k取决于几个因素，包括(i)水凝胶的形成，(ii)水凝胶的动员进入并阻塞最导电的孔隙，(iii)渗透力和水凝胶交联键强度的平衡，(iv)水凝胶形成的动力学，(v)聚合物在膨润土颗粒或颗粒聚集体表面的吸附。
{"title":"Mechanisms controlling the hydraulic conductivity of anionic polymer-enhanced GCLs","authors":"A. Norris, Joseph Scalia IV, C. Shackelford","doi":"10.1680/jgein.21.00051","DOIUrl":"https://doi.org/10.1680/jgein.21.00051","url":null,"abstract":"The hydraulic conductivity (k) of specimens of enhanced-bentonite geosynthetic clay liners (EB-GCLs) comprising anionic polymers permeated with concentrated salt solutions, i.e., 500 mM NaCl and 167 mM CaCl2, was measured to determine the effects of polymer properties and specimen preparation method on the k and the associated roles of polymer retention and elution in dictating the measured k. The results of hydrogel formation tests illustrated that poly(acrylic acid) hydrogel was formed in solutions tested during EB-GCL hydration. A dry sprinkling method of specimen preparation resulted in low k (≤ 5.5×10−11 m/s) in multiple EB-GCLs, with a low fraction (≤ 2.5 %) of retained polymer. In contrast, polymer elution from EB-GCLs prepared using a dry mixing method resulted in interaggregate seepage and an increase in k. Higher polymer retention occurred for the wet-mixed EB-GCLs, but did not directly correlate to low k. The long-term k of the EB-GCLs is dependent on several factors, including (i) formation of hydrogel, (ii) mobilization of hydrogel into and blocking of the most conductive pores, (iii) balance of seepage forces and hydrogel crosslink bond strength, (iv) kinetics of hydrogel formation, and (v) adsorption of polymer to the surfaces of the bentonite particles or aggregates of particles.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2022-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46964563","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}
High-density polyethylene (HDPE) geomembranes (GMs) are frequently used as fluid barrier components of cover systems for mine site reclamation in regions that are prone to freeze–thaw cycles (FTCs). However, HDPE GMs are more susceptible to stress cracking than linear low-density polyethylene (LLDPE) GMs. Hence, LLDPE GMs are increasingly considered as alternatives to HDPE GMs in cover systems. Nevertheless, little information is available on LLDPE compared to HDPE GMs. Moreover, little is known about the changes in the fluid barrier properties (the equivalent hydraulic conductivity and the oxygen sorption and diffusion coefficients) for these two materials with FTCs. The purpose of this study is therefore to compare the effects of FTCs on the tensile, hydraulic, and oxygen sorption and diffusion properties of HDPE and LLDPE GMs. To do so, GM sheets were subjected up to 300 FTCs. Mechanically, both GMs got stiffer and their tensile break properties increased with increasing number of FTCs. However, although the GM fluid barrier properties changed with FTCs, the equivalent hydraulic conductivity, and the oxygen permeation coefficient remained within an order of magnitude of 10−14 m/s and 10−14 m−14/s, respectively. Up to 300 FTCs would therefore have no adverse effects on HDPE and LLDPE GMs.
{"title":"Effects of freeze–thaw cycles on the properties of polyethylene geomembranes","authors":"R. F. M. Rarison, M. Mbonimpa, B. Bussière","doi":"10.1680/jgein.21.00043a","DOIUrl":"https://doi.org/10.1680/jgein.21.00043a","url":null,"abstract":"High-density polyethylene (HDPE) geomembranes (GMs) are frequently used as fluid barrier components of cover systems for mine site reclamation in regions that are prone to freeze–thaw cycles (FTCs). However, HDPE GMs are more susceptible to stress cracking than linear low-density polyethylene (LLDPE) GMs. Hence, LLDPE GMs are increasingly considered as alternatives to HDPE GMs in cover systems. Nevertheless, little information is available on LLDPE compared to HDPE GMs. Moreover, little is known about the changes in the fluid barrier properties (the equivalent hydraulic conductivity and the oxygen sorption and diffusion coefficients) for these two materials with FTCs. The purpose of this study is therefore to compare the effects of FTCs on the tensile, hydraulic, and oxygen sorption and diffusion properties of HDPE and LLDPE GMs. To do so, GM sheets were subjected up to 300 FTCs. Mechanically, both GMs got stiffer and their tensile break properties increased with increasing number of FTCs. However, although the GM fluid barrier properties changed with FTCs, the equivalent hydraulic conductivity, and the oxygen permeation coefficient remained within an order of magnitude of 10−14 m/s and 10−14 m−14/s, respectively. Up to 300 FTCs would therefore have no adverse effects on HDPE and LLDPE GMs.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2022-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47651954","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}
Geosynthetics have been used to reinforce soils for over 4 decades. They can also be used as reinforcement in buried pipe installations to reduce stresses and strains in the pipe, as well as the consequences of pipe explosions. This paper investigates the use of geosynthetic reinforcement to protect a flexible buried pipe from the effects of a localized surcharge on the soil surface. Large scale tests were carried out on an instrumented PVC pipe buried in a rather loose sand. Different types and arrangements of the reinforcement layer were investigated. The results obtained address the relations between stresses on the pipe, pipe strains and pipe deflections and show that the presence of the reinforcement can reduce significantly vertical and horizontal stresses on the pipe as well as pipe deformations. An elastic solution for the prediction of strains at the pipe crown was employed, whose predictions compared well with the experimental results.
{"title":"Stresses and Strains in a flexible pipe buried in geosynthetic reinforced soil","authors":"E. Palmeira, A. C. G. Pires","doi":"10.1680/jgein.21.00054","DOIUrl":"https://doi.org/10.1680/jgein.21.00054","url":null,"abstract":"Geosynthetics have been used to reinforce soils for over 4 decades. They can also be used as reinforcement in buried pipe installations to reduce stresses and strains in the pipe, as well as the consequences of pipe explosions. This paper investigates the use of geosynthetic reinforcement to protect a flexible buried pipe from the effects of a localized surcharge on the soil surface. Large scale tests were carried out on an instrumented PVC pipe buried in a rather loose sand. Different types and arrangements of the reinforcement layer were investigated. The results obtained address the relations between stresses on the pipe, pipe strains and pipe deflections and show that the presence of the reinforcement can reduce significantly vertical and horizontal stresses on the pipe as well as pipe deformations. An elastic solution for the prediction of strains at the pipe crown was employed, whose predictions compared well with the experimental results.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2022-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42910790","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 paper examines the gas flow performance of needle-punched geosynthetic clay liners (GCLs) overlap seams over a range of gravimetric moisture content, including the effect of vertical stress and unevenness of the overlaps. The gas permeability of the GCL overlapped seams was higher than that of non-overlapped GCLs, especially at higher gravimetric moisture content, as the intactness of the overlapped areas was challenging to maintain due to the GCL swelling process. The gas flow rate of uneven overlapped GCLs was greater than that of a flat overlap (even seam) irrespective of the vertical stress. This paper highlights the importance of factoring in the gas flow assessment of cover systems the possibility of the unevenness of the GCL panels overlaps.
{"title":"Gas permeability of geosynthetic clay liners overlap seams","authors":"Q. Wang, A. Bouazza, H. Xie","doi":"10.1680/jgein.21.00092","DOIUrl":"https://doi.org/10.1680/jgein.21.00092","url":null,"abstract":"This paper examines the gas flow performance of needle-punched geosynthetic clay liners (GCLs) overlap seams over a range of gravimetric moisture content, including the effect of vertical stress and unevenness of the overlaps. The gas permeability of the GCL overlapped seams was higher than that of non-overlapped GCLs, especially at higher gravimetric moisture content, as the intactness of the overlapped areas was challenging to maintain due to the GCL swelling process. The gas flow rate of uneven overlapped GCLs was greater than that of a flat overlap (even seam) irrespective of the vertical stress. This paper highlights the importance of factoring in the gas flow assessment of cover systems the possibility of the unevenness of the GCL panels overlaps.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2022-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47591814","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. Liu, C. Gao, K. Fan, C. Zhang, Z. Wang, C. Shen, Z. Han
Shallow slope failure often occurs in expansive soil channel slopes because of the strong swelling–shrinkage behavior of the expansive soils and the well-developed fissures. In this paper, a repair method for expansive soil channel slopes using soilbags is proposed. Model tests were carried out to illustrate the effect of this repair method. The test results indicate that the assembly of soilbags arranged on the slope limits the deformation of expansive soils after water absorption and reduces the infiltration and evaporation during the drying-wetting cycle process. A method for analyzing the sliding stability of the repaired slope was suggested and a case study of repairing a 65m testing expansive soil channel slope with soilbags was presented in the South-to-North Water Transfer Project in China. The monitoring of vertical and lateral displacements of the testing slope demonstrates the effectiveness of using soilbags to repair the expansive soil channel slopes.
{"title":"Repairing expansive soil channel slope with soilbags","authors":"S. Liu, C. Gao, K. Fan, C. Zhang, Z. Wang, C. Shen, Z. Han","doi":"10.1680/jgein.22.00254","DOIUrl":"https://doi.org/10.1680/jgein.22.00254","url":null,"abstract":"Shallow slope failure often occurs in expansive soil channel slopes because of the strong swelling–shrinkage behavior of the expansive soils and the well-developed fissures. In this paper, a repair method for expansive soil channel slopes using soilbags is proposed. Model tests were carried out to illustrate the effect of this repair method. The test results indicate that the assembly of soilbags arranged on the slope limits the deformation of expansive soils after water absorption and reduces the infiltration and evaporation during the drying-wetting cycle process. A method for analyzing the sliding stability of the repaired slope was suggested and a case study of repairing a 65m testing expansive soil channel slope with soilbags was presented in the South-to-North Water Transfer Project in China. The monitoring of vertical and lateral displacements of the testing slope demonstrates the effectiveness of using soilbags to repair the expansive soil channel slopes.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49147038","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 paper presents an evaluation of the pull-out behaviour of tyre strip-reinforced granular soil. The three-dimensional discrete element method (DEM) and laboratory testing were used to systematically calibrate the soil particles and the tyre strip based on their stress-strain relationship, tensile stiffness, and interface shear strength. Particle shapes were considered during sand calibration. The scaled pull-out resistance was found to match that of the experimental data. Contributions of the sectional interface shear force to the total pull-out resistance were calculated to explain the progressive failure mechanism mobilised at the tyre-sand interface. The shear force along the tyre strip was not uniformly distributed but higher in the middle portion of the tyre strip. It gradually extended towards the front end of the tyre strip before global interface slipping failure occurred. Comparing the pull-out behaviour of extensible and inextensible tyre strips, the elastic deformation of the tyre strip delayed the occurrence but not the magnitude of peak pull-out force. Micro-mechanical interactions between tyre strip and sand during shear mobilisation were discussed, and induced anisotropy was revealed. The experimental and DEM investigation results in this study provide researchers with an improved understanding of tyre-soil interaction under pull-out loads.
{"title":"DEM investigation of shear mobilisation during tyre strip pull-out test","authors":"Z. Ren, Y. Cheng, X. Xu, L. Li","doi":"10.1680/jgein.21.00100","DOIUrl":"https://doi.org/10.1680/jgein.21.00100","url":null,"abstract":"This paper presents an evaluation of the pull-out behaviour of tyre strip-reinforced granular soil. The three-dimensional discrete element method (DEM) and laboratory testing were used to systematically calibrate the soil particles and the tyre strip based on their stress-strain relationship, tensile stiffness, and interface shear strength. Particle shapes were considered during sand calibration. The scaled pull-out resistance was found to match that of the experimental data. Contributions of the sectional interface shear force to the total pull-out resistance were calculated to explain the progressive failure mechanism mobilised at the tyre-sand interface. The shear force along the tyre strip was not uniformly distributed but higher in the middle portion of the tyre strip. It gradually extended towards the front end of the tyre strip before global interface slipping failure occurred. Comparing the pull-out behaviour of extensible and inextensible tyre strips, the elastic deformation of the tyre strip delayed the occurrence but not the magnitude of peak pull-out force. Micro-mechanical interactions between tyre strip and sand during shear mobilisation were discussed, and induced anisotropy was revealed. The experimental and DEM investigation results in this study provide researchers with an improved understanding of tyre-soil interaction under pull-out loads.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46146890","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}
Five spring-based trapdoor tests allowing continuous displacement during both fill placement and localized static loading were conducted. A quartz sand was used as the test fill. Biaxial geogrids with and without ribs, having two different reinforcement stiffnesses, were used as reinforcement materials. Test results show that when two low-stiffness geogrid reinforcement layers were used, higher reinforcement spacing ratios (defined as the ratio of the reinforcement spacing between two reinforcement layers to the trapdoor width) induced more stable and efficient load transfer generally. Consequently, an optimum value of 0.3 and a worst-case value of 0.1 for the reinforcement spacing ratio were obtained and considered as representatives of two low-stiffness reinforcement layers to compare with a single high-stiffness reinforcement layer, where their total reinforcement stiffnesses were approximately same. Generally, the inclusion of two low-stiffness reinforcement layers induced more stable load transfer. More importantly, as compared with a single high-stiffness reinforcement layer, two low-stiffness reinforcement layers with the optimum reinforcement spacing ratio enhanced load transfer and induced less overall tensile forces, whereas the reinforcement arrangement with the worst reinforcement spacing ratio induced similar load transfer efficiency and overall tensile forces.
{"title":"Effects of Reinforcement Arrangements on Load Transfer under Localized Static Loading","authors":"G. Li, C. Xu, C. Yoo, P. Shen, T. Wang, Q. Wang","doi":"10.1680/jgein.22.00265","DOIUrl":"https://doi.org/10.1680/jgein.22.00265","url":null,"abstract":"Five spring-based trapdoor tests allowing continuous displacement during both fill placement and localized static loading were conducted. A quartz sand was used as the test fill. Biaxial geogrids with and without ribs, having two different reinforcement stiffnesses, were used as reinforcement materials. Test results show that when two low-stiffness geogrid reinforcement layers were used, higher reinforcement spacing ratios (defined as the ratio of the reinforcement spacing between two reinforcement layers to the trapdoor width) induced more stable and efficient load transfer generally. Consequently, an optimum value of 0.3 and a worst-case value of 0.1 for the reinforcement spacing ratio were obtained and considered as representatives of two low-stiffness reinforcement layers to compare with a single high-stiffness reinforcement layer, where their total reinforcement stiffnesses were approximately same. Generally, the inclusion of two low-stiffness reinforcement layers induced more stable load transfer. More importantly, as compared with a single high-stiffness reinforcement layer, two low-stiffness reinforcement layers with the optimum reinforcement spacing ratio enhanced load transfer and induced less overall tensile forces, whereas the reinforcement arrangement with the worst reinforcement spacing ratio induced similar load transfer efficiency and overall tensile forces.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46422566","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}
Composite pile with a stiffer core and gravel shell is a newly emerging column technology to improve soft soil by combining the advantages in accelerating consolidation and increasing loading bearing capacity. In practice, the composite piles may be constructed into various forms with different cross-section shapes. Moreover, soft soil particles may be transferred along with the seepage and intrude into the gravel shell and thereby clog them. In this paper, by converting the noncircular cross-sectional compile pile into a hollow cylindrical unit cell and considering the time-dependent clogging effect, an analytical model for the consolidation of composite ground stabilized by composite piles is proposed. Analytical solutions are then obtained for instantaneously loading and multi-stage instantaneously loading under the equal-strain condition. Moreover, the variation of the stress with depth caused by surcharge loading is also incorporated in the analysis. The reasonability of the solutions is verified by degenerating them to some previous solutions. Furthermore, the solutions are applied to a laboratory test to investigate consolidation. The predicted results are compared to the measured data and a good agreement is observed between them. Finally, a parametric study is conducted to investigate the influence of several parameters on the consolidation behavior.
{"title":"Analytical solutions for consolidation of composite ground improved by composite piles considering clogging effect","authors":"J. Shan, M. Lu, K. Yang","doi":"10.1680/jgein.21.00109","DOIUrl":"https://doi.org/10.1680/jgein.21.00109","url":null,"abstract":"Composite pile with a stiffer core and gravel shell is a newly emerging column technology to improve soft soil by combining the advantages in accelerating consolidation and increasing loading bearing capacity. In practice, the composite piles may be constructed into various forms with different cross-section shapes. Moreover, soft soil particles may be transferred along with the seepage and intrude into the gravel shell and thereby clog them. In this paper, by converting the noncircular cross-sectional compile pile into a hollow cylindrical unit cell and considering the time-dependent clogging effect, an analytical model for the consolidation of composite ground stabilized by composite piles is proposed. Analytical solutions are then obtained for instantaneously loading and multi-stage instantaneously loading under the equal-strain condition. Moreover, the variation of the stress with depth caused by surcharge loading is also incorporated in the analysis. The reasonability of the solutions is verified by degenerating them to some previous solutions. Furthermore, the solutions are applied to a laboratory test to investigate consolidation. The predicted results are compared to the measured data and a good agreement is observed between them. Finally, a parametric study is conducted to investigate the influence of several parameters on the consolidation behavior.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43543806","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}
W. Guo, X. Wang, C. He, L. Jiang, Y. Long, Z. Guo, Q. Yan, L. Zhao, Y. Lin
The seismic performance of embankments is an important consideration for the design and construction of high-speed railways (HSRs) in near-fault areas. Incorporating geosynthetics into embankment soil can improve seismic resistance. However, the effect of different reinforcement methods on the seismic performance of embankments is not well understood. In this study, two 1:20 scaled embankment models (full-length-geosynthetics reinforced pile-supported embankment (FRPE) and turn-back-geosynthetics reinforced pile-supported embankment (TRPE)) were tested on a shaking table to compare their seismic performance and failure characteristics. The results show that, under near-fault bidirectional seismic excitation, the pile foundations of both embankments exhibited bending deformation, with the largest bending moment was the largest in the middle of the pile body. The TRPE reduced the vertical dynamic response of the embankment slope but exhibited a more remarkable horizontal dynamic response than the FRPE. Furthermore, the embankment deformation and excess pore water pressure of the TRPE were generally larger than those of the FRPE. Nonetheless, the TRPE has potential application in practical engineering as it ensures earthquake resistance, with higher economic benefits.
{"title":"Seismic performance of near-fault geosynthetic-reinforced pile-supported embankment","authors":"W. Guo, X. Wang, C. He, L. Jiang, Y. Long, Z. Guo, Q. Yan, L. Zhao, Y. Lin","doi":"10.1680/jgein.21.00105","DOIUrl":"https://doi.org/10.1680/jgein.21.00105","url":null,"abstract":"The seismic performance of embankments is an important consideration for the design and construction of high-speed railways (HSRs) in near-fault areas. Incorporating geosynthetics into embankment soil can improve seismic resistance. However, the effect of different reinforcement methods on the seismic performance of embankments is not well understood. In this study, two 1:20 scaled embankment models (full-length-geosynthetics reinforced pile-supported embankment (FRPE) and turn-back-geosynthetics reinforced pile-supported embankment (TRPE)) were tested on a shaking table to compare their seismic performance and failure characteristics. The results show that, under near-fault bidirectional seismic excitation, the pile foundations of both embankments exhibited bending deformation, with the largest bending moment was the largest in the middle of the pile body. The TRPE reduced the vertical dynamic response of the embankment slope but exhibited a more remarkable horizontal dynamic response than the FRPE. Furthermore, the embankment deformation and excess pore water pressure of the TRPE were generally larger than those of the FRPE. Nonetheless, the TRPE has potential application in practical engineering as it ensures earthquake resistance, with higher economic benefits.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":4.5,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46344620","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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