Pub Date : 2022-02-05DOI: 10.1080/17486025.2022.2029954
H. Nghiem
ABSTRACT This paper investigates the torsional dynamic response of a single pile with a circular cross-section embedded in multi-layered soils. The energy principles and variational approach are employed to establish the governing equations of the pile-soil system subjected to dynamic torque applied at the pile head in the frequency domain. The proposed solution is based on the finite element method for a bar on an elastic foundation to provide the torsional dynamic subgrade reaction, angle of twist, torque along the pile and the torsional impedance at the pile head. The accuracy of the proposed method is verified by comparing the analysis results with those of existing analytical solutions. Parametric studies are also performed to investigate the influence of the soil properties and the excitation frequencies on the stiffness and radiation damping of the pile-soil system.
{"title":"Variational approach for torsional dynamic response of a single pile in multi-layered soils","authors":"H. Nghiem","doi":"10.1080/17486025.2022.2029954","DOIUrl":"https://doi.org/10.1080/17486025.2022.2029954","url":null,"abstract":"ABSTRACT This paper investigates the torsional dynamic response of a single pile with a circular cross-section embedded in multi-layered soils. The energy principles and variational approach are employed to establish the governing equations of the pile-soil system subjected to dynamic torque applied at the pile head in the frequency domain. The proposed solution is based on the finite element method for a bar on an elastic foundation to provide the torsional dynamic subgrade reaction, angle of twist, torque along the pile and the torsional impedance at the pile head. The accuracy of the proposed method is verified by comparing the analysis results with those of existing analytical solutions. Parametric studies are also performed to investigate the influence of the soil properties and the excitation frequencies on the stiffness and radiation damping of the pile-soil system.","PeriodicalId":46470,"journal":{"name":"Geomechanics and Geoengineering-An International Journal","volume":"18 1","pages":"239 - 251"},"PeriodicalIF":1.3,"publicationDate":"2022-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46387923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-16DOI: 10.1080/17486025.2021.2023766
K. Bajaj, P. Anbazhagan
ABSTRACT Ground motion input layer depth and Vs are crucial parameters in computing representative surface amplification factor, especially for deep deposits where bedrock depth is unknown. For many soil sites, seismic bedrock depth is unknown and randomly assigning the input motion to any layer may result in bias response. The aim of this study is to understand the effect of input layer velocity or depth on surface response parameters. Further determining the appropriate layer for giving the input ground motion for reliable estimation of response parameters by carrying out detailed site-response analysis. For the analysis, surface and bedrock ground motion recordings from KiK-Net downhole are used. Total stress nonlinear site-response analysis has been carried out by varying the velocity and depth to input the ground motion recorded at the bottom most layer for deep and shallow profiles. Using linear mixed effect models on residuals calculated from recorded and predicted surface spectra, fixed bias and σ are calculated. Layer having Vs ≥ 1500 ( 150) m/s is suitable for capturing the surface amplification spectra for both deep and shallow deposits.
{"title":"Effective input velocity and depth for deep and shallow sites for site response analysis","authors":"K. Bajaj, P. Anbazhagan","doi":"10.1080/17486025.2021.2023766","DOIUrl":"https://doi.org/10.1080/17486025.2021.2023766","url":null,"abstract":"ABSTRACT Ground motion input layer depth and Vs are crucial parameters in computing representative surface amplification factor, especially for deep deposits where bedrock depth is unknown. For many soil sites, seismic bedrock depth is unknown and randomly assigning the input motion to any layer may result in bias response. The aim of this study is to understand the effect of input layer velocity or depth on surface response parameters. Further determining the appropriate layer for giving the input ground motion for reliable estimation of response parameters by carrying out detailed site-response analysis. For the analysis, surface and bedrock ground motion recordings from KiK-Net downhole are used. Total stress nonlinear site-response analysis has been carried out by varying the velocity and depth to input the ground motion recorded at the bottom most layer for deep and shallow profiles. Using linear mixed effect models on residuals calculated from recorded and predicted surface spectra, fixed bias and σ are calculated. Layer having Vs ≥ 1500 ( 150) m/s is suitable for capturing the surface amplification spectra for both deep and shallow deposits.","PeriodicalId":46470,"journal":{"name":"Geomechanics and Geoengineering-An International Journal","volume":"18 1","pages":"193 - 207"},"PeriodicalIF":1.3,"publicationDate":"2022-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46278727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-11DOI: 10.1080/17486025.2022.2025922
M. Morsy, Y. El-Mossallamy, A. Salah
ABSTRACT Piles in soft soil supporting bridge abutments are often exposed to passive loading induced by adjacent bridge approach embankment. Several methods for analysis of passive piles have been developed, but the international design specifications do not recommend a specific method for the analysis of passive piles. Therefore, the applicability of existing empirical and analytical analysis (conventional) methods is examined by comparing their outputs with those of a validated finite element model (FEM) at various adjacent embankment stress levels, and construction times, soft clay thicknesses, and pile spacing to diameter ratios. Outputs of both conventional methods and FEM show that increasing the embankment stress, thickness of soft clay layer, and pile spacing to diameter ratio results in an increase in the lateral pile displacement, maximum bending moment, and lateral pressure, and vice-versa on increasing embankment construction time. The outputs of the conventional analysis methods are compared to the FEM outputs and are underestimated except for few cases. The conventional analysis methods may yield better predictions at pile diameter-to-spacing ratio equals 3–4 for a soil preloaded prior to pile construction to a degree of consolidation greater than 50%.
{"title":"Evaluation of passive pile analysis methods using three-dimensional finite element analysis","authors":"M. Morsy, Y. El-Mossallamy, A. Salah","doi":"10.1080/17486025.2022.2025922","DOIUrl":"https://doi.org/10.1080/17486025.2022.2025922","url":null,"abstract":"ABSTRACT Piles in soft soil supporting bridge abutments are often exposed to passive loading induced by adjacent bridge approach embankment. Several methods for analysis of passive piles have been developed, but the international design specifications do not recommend a specific method for the analysis of passive piles. Therefore, the applicability of existing empirical and analytical analysis (conventional) methods is examined by comparing their outputs with those of a validated finite element model (FEM) at various adjacent embankment stress levels, and construction times, soft clay thicknesses, and pile spacing to diameter ratios. Outputs of both conventional methods and FEM show that increasing the embankment stress, thickness of soft clay layer, and pile spacing to diameter ratio results in an increase in the lateral pile displacement, maximum bending moment, and lateral pressure, and vice-versa on increasing embankment construction time. The outputs of the conventional analysis methods are compared to the FEM outputs and are underestimated except for few cases. The conventional analysis methods may yield better predictions at pile diameter-to-spacing ratio equals 3–4 for a soil preloaded prior to pile construction to a degree of consolidation greater than 50%.","PeriodicalId":46470,"journal":{"name":"Geomechanics and Geoengineering-An International Journal","volume":"18 1","pages":"222 - 238"},"PeriodicalIF":1.3,"publicationDate":"2022-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43432091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-09DOI: 10.1080/17486025.2021.2024897
Waleed R. Abdullah, A. Ashkanani, Waleed K. Eid, R. Al-Fares, M. Alkhamis
ABSTRACT The reuse of scrap rubber crumbs mixed with sand as lightweight fills is considered as a sustainable application. However, the performance of sand–crumb mixtures and the optimum content of crumbs have not been consistent. The purpose of this study was to investigate the feasibility of using sand–crumb mixtures for applications such as embankment fills, backfilling for subgrades, and retaining walls, and assess the optimum crumb contents in the mix. Mixtures of fill sand and rubber crumbs with sizes of 1–2 mm at crumb contents of 0%, 10%, 20%, and 30% by weight of dry sand were tested in a laboratory for compaction and penetration using the California bearing ratio (CBR) test and for shear strength using direct shear tests. The dry unit weight, CBR, dilation, and friction angle decreased as the crumb content increased, while apparent cohesion was introduced in the mixtures with the addition of crumbs, and it increased with the crumb content. Sand–crumb mixtures were effective as lightweight fill materials over soft soils, but were not suitable as subgrade materials. Furthermore, sand–crumb mixtures with an optimum crumb content of 20% provided the maximum reduction in lateral earth pressure when they were used as backfill materials behind retaining walls.
{"title":"Evaluation of Sand–tire Crumb Mixtures as Lightweight Fill Materials","authors":"Waleed R. Abdullah, A. Ashkanani, Waleed K. Eid, R. Al-Fares, M. Alkhamis","doi":"10.1080/17486025.2021.2024897","DOIUrl":"https://doi.org/10.1080/17486025.2021.2024897","url":null,"abstract":"ABSTRACT The reuse of scrap rubber crumbs mixed with sand as lightweight fills is considered as a sustainable application. However, the performance of sand–crumb mixtures and the optimum content of crumbs have not been consistent. The purpose of this study was to investigate the feasibility of using sand–crumb mixtures for applications such as embankment fills, backfilling for subgrades, and retaining walls, and assess the optimum crumb contents in the mix. Mixtures of fill sand and rubber crumbs with sizes of 1–2 mm at crumb contents of 0%, 10%, 20%, and 30% by weight of dry sand were tested in a laboratory for compaction and penetration using the California bearing ratio (CBR) test and for shear strength using direct shear tests. The dry unit weight, CBR, dilation, and friction angle decreased as the crumb content increased, while apparent cohesion was introduced in the mixtures with the addition of crumbs, and it increased with the crumb content. Sand–crumb mixtures were effective as lightweight fill materials over soft soils, but were not suitable as subgrade materials. Furthermore, sand–crumb mixtures with an optimum crumb content of 20% provided the maximum reduction in lateral earth pressure when they were used as backfill materials behind retaining walls.","PeriodicalId":46470,"journal":{"name":"Geomechanics and Geoengineering-An International Journal","volume":"18 1","pages":"208 - 221"},"PeriodicalIF":1.3,"publicationDate":"2022-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42226510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-06DOI: 10.1080/17486025.2021.2015977
Iman Hosseinpour, A. Ghorbani, Javad Zarei, Sunil Ranjan Mohapatra
ABSTRACT Compacted granular columns are frequently used to mitigate construction difficulties over soft soil deposits through a combination of densification, increasing load-bearing capacity and improvement in consolidation features. The behaviour of granular columns under vertical loading has been well recognised; however, this research is aimed to investigate the behaviour of granular column-reinforced soft soil subjected to shear stress. In this contribution, large-scale direct shear tests were performed, and the influence of undrained shear strength of clay, diameter of granular column and relative density of aggregates was examined. In general, the use of granular column has been shown to improve the shear resistance of the composite ground, which was found to be much significant at lower undrained shear strength of the soft clay. Increasing density of aggregates from Dr = 50% to 90% caused a large portion of the shear stress to be sustained by the accumulated friction of aggregates as the internal friction angle of the treated clay increased from 0 to 28°. In addition, test results revealed that the use of highly compacted column yields a lowered shear displacement at failure, which was indirect evidence of stiffness improvement of the composite ground.
{"title":"Experimental study on the behaviour of granular column-treated soft clay under shear loading","authors":"Iman Hosseinpour, A. Ghorbani, Javad Zarei, Sunil Ranjan Mohapatra","doi":"10.1080/17486025.2021.2015977","DOIUrl":"https://doi.org/10.1080/17486025.2021.2015977","url":null,"abstract":"ABSTRACT Compacted granular columns are frequently used to mitigate construction difficulties over soft soil deposits through a combination of densification, increasing load-bearing capacity and improvement in consolidation features. The behaviour of granular columns under vertical loading has been well recognised; however, this research is aimed to investigate the behaviour of granular column-reinforced soft soil subjected to shear stress. In this contribution, large-scale direct shear tests were performed, and the influence of undrained shear strength of clay, diameter of granular column and relative density of aggregates was examined. In general, the use of granular column has been shown to improve the shear resistance of the composite ground, which was found to be much significant at lower undrained shear strength of the soft clay. Increasing density of aggregates from Dr = 50% to 90% caused a large portion of the shear stress to be sustained by the accumulated friction of aggregates as the internal friction angle of the treated clay increased from 0 to 28°. In addition, test results revealed that the use of highly compacted column yields a lowered shear displacement at failure, which was indirect evidence of stiffness improvement of the composite ground.","PeriodicalId":46470,"journal":{"name":"Geomechanics and Geoengineering-An International Journal","volume":"18 1","pages":"121 - 132"},"PeriodicalIF":1.3,"publicationDate":"2022-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46932922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01Epub Date: 2022-02-26DOI: 10.1007/s00706-022-02892-1
Kehinde M Taiwo, Lukasz T Olenginski, Felix Nußbaumer, Hyeyeon Nam, Stefan Hilber, Christoph Kreutz, T Kwaku Dayie
Several isotope-labeling strategies have been developed for the study of RNA by nuclear magnetic resonance (NMR) spectroscopy. Here, we report a combined chemical and enzymatic synthesis of [7-15N]-guanosine-5'-triphosphates for incorporation into RNA via T7 RNA polymerase-based in vitro transcription. We showcase the utility of these labels to probe both structure and dynamics in two biologically important RNAs.
Graphical abstract:
Supplementary information: The online version contains supplementary material available at 10.1007/s00706-022-02892-1.
{"title":"Synthesis of [7-<sup>15</sup>N]-GTPs for RNA structure and dynamics by NMR spectroscopy.","authors":"Kehinde M Taiwo, Lukasz T Olenginski, Felix Nußbaumer, Hyeyeon Nam, Stefan Hilber, Christoph Kreutz, T Kwaku Dayie","doi":"10.1007/s00706-022-02892-1","DOIUrl":"10.1007/s00706-022-02892-1","url":null,"abstract":"<p><p>Several isotope-labeling strategies have been developed for the study of RNA by nuclear magnetic resonance (NMR) spectroscopy. Here, we report a combined chemical and enzymatic synthesis of [7-<sup>15</sup>N]-guanosine-5'-triphosphates for incorporation into RNA via T7 RNA polymerase-based in vitro transcription. We showcase the utility of these labels to probe both structure and dynamics in two biologically important RNAs.</p><p><strong>Graphical abstract: </strong></p><p><strong>Supplementary information: </strong>The online version contains supplementary material available at 10.1007/s00706-022-02892-1.</p>","PeriodicalId":46470,"journal":{"name":"Geomechanics and Geoengineering-An International Journal","volume":"18 1","pages":"293-299"},"PeriodicalIF":1.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8948113/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87270712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-31DOI: 10.1080/17486025.2021.2015457
B. O’Kelly, A. Soltani
It is the authors’ opinion that confusion could arise from the analyses and explanations of the experimental fall-cone (FC) results presented in the paper by Nagaraj et al. (2018), which has been compounded in their recent Closure (Nagaraj et al. 2021) to the Discussion of their 2018 paper by Haigh et al. (2021). For the investigation by Nagaraj et al. (2018), the FC method, as per the British Standards Institution (BSI) BS 1377–2 (1990), was used to determine the liquid limit (i.e. wL-FC(BSI)), which defines the liquid-limit state transition as the water content corresponding to a penetration depth of hL = 20 mm for a smooth, polished 30°–80 g FC with its tip initially just contacting the top surface of the fine-grained soil test specimen. The FC test was originally developed for measuring undrained shear strength (Hansbo 1957, O’Kelly et al. 2018) and was subsequently adopted for determination of the FC liquid limit (e.g. BSI 1975), with the FC-deduced saturated remoulded undrained shear strength (i.e. cu(FC)) of a finegrained soil tested at a given water content determined as follows:
作者认为，对Nagaraj等人（2018）在论文中提出的实验落锥（FC）结果的分析和解释可能会引起混淆，这在他们最近的结论（Nagaraj et al.2021）和Haigh等人（2021）对2018年论文的讨论中得到了补充。对于Nagaraj等人的调查。（2018），根据英国标准协会（BSI）BS 1377–2（1990），使用FC方法来确定液限（即wL FC（BSI，抛光30°–80 g FC，其尖端最初仅接触细粒土壤试样的顶面。FC试验最初是为测量不排水抗剪强度而开发的（Hansbo 1957，O'Kelly等人，2018），随后被用于确定FC液限（例如BSI 1975），FC推导出的在给定含水量下测试的细粒土的饱和重塑不排水抗剪切强度（即cu（FC））如下所示：
{"title":"Discussion of ‘Factors influencing undrained strength of fine-grained soils at high water contents’ [Geomechanics and Geoengineering 13(4), 276–287]","authors":"B. O’Kelly, A. Soltani","doi":"10.1080/17486025.2021.2015457","DOIUrl":"https://doi.org/10.1080/17486025.2021.2015457","url":null,"abstract":"It is the authors’ opinion that confusion could arise from the analyses and explanations of the experimental fall-cone (FC) results presented in the paper by Nagaraj et al. (2018), which has been compounded in their recent Closure (Nagaraj et al. 2021) to the Discussion of their 2018 paper by Haigh et al. (2021). For the investigation by Nagaraj et al. (2018), the FC method, as per the British Standards Institution (BSI) BS 1377–2 (1990), was used to determine the liquid limit (i.e. wL-FC(BSI)), which defines the liquid-limit state transition as the water content corresponding to a penetration depth of hL = 20 mm for a smooth, polished 30°–80 g FC with its tip initially just contacting the top surface of the fine-grained soil test specimen. The FC test was originally developed for measuring undrained shear strength (Hansbo 1957, O’Kelly et al. 2018) and was subsequently adopted for determination of the FC liquid limit (e.g. BSI 1975), with the FC-deduced saturated remoulded undrained shear strength (i.e. cu(FC)) of a finegrained soil tested at a given water content determined as follows:","PeriodicalId":46470,"journal":{"name":"Geomechanics and Geoengineering-An International Journal","volume":"18 1","pages":"170 - 174"},"PeriodicalIF":1.3,"publicationDate":"2021-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44121453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-31DOI: 10.1080/17486025.2021.2019320
H. Ahmad, Mohammad Hosein Hoseini, A. Mahboubi, A. Noorzad, M. Zamanian
ABSTRACT Due to the shortage of urban land, new buildings are constructed adjacent to old buildings. In this regard, there is limited information about the behaviour of the shallow foundations adjacent to the excavation. In this research, a series of experimental and numerical studies are conducted on reinforced and unreinforced granular soils adjacent to excavation loaded with square footings. The experimental results are in good agreement with the numerical study. Numerical investigations were carried out on sandy excavation by varying the footing distance from the edge of the different granular excavations. It was found that by using three reinforcing layers, the ultimate bearing capacity would increase. Additionally, excavation has no significant effect in the vicinity of 4B, in which B is the footing width. Furthermore, the need to build new large buildings in the vicinity of each other has reduced the distances between square footings and, as a result, has created the phenomenon of interference in the footings and excavation. This occurs through the interference of wedges and rupture surfaces. Since this phenomenon bears a substantial result on the bearing capacity of shallow footings, this work investigates the effect of interference of ruptured wedges on the carriage capacity, settlement, and deformation of square footings. The optimum interference factor is defined at spacings of 2B and 3B for dense and loose reinforced sands, respectively. Furthermore, by including three continuous geogrid layers underneath two square footing interferences, their behaviour will be improved.
{"title":"Effect of sheet pile wall on the load-settlement behaviour of square footing nearby excavation","authors":"H. Ahmad, Mohammad Hosein Hoseini, A. Mahboubi, A. Noorzad, M. Zamanian","doi":"10.1080/17486025.2021.2019320","DOIUrl":"https://doi.org/10.1080/17486025.2021.2019320","url":null,"abstract":"ABSTRACT Due to the shortage of urban land, new buildings are constructed adjacent to old buildings. In this regard, there is limited information about the behaviour of the shallow foundations adjacent to the excavation. In this research, a series of experimental and numerical studies are conducted on reinforced and unreinforced granular soils adjacent to excavation loaded with square footings. The experimental results are in good agreement with the numerical study. Numerical investigations were carried out on sandy excavation by varying the footing distance from the edge of the different granular excavations. It was found that by using three reinforcing layers, the ultimate bearing capacity would increase. Additionally, excavation has no significant effect in the vicinity of 4B, in which B is the footing width. Furthermore, the need to build new large buildings in the vicinity of each other has reduced the distances between square footings and, as a result, has created the phenomenon of interference in the footings and excavation. This occurs through the interference of wedges and rupture surfaces. Since this phenomenon bears a substantial result on the bearing capacity of shallow footings, this work investigates the effect of interference of ruptured wedges on the carriage capacity, settlement, and deformation of square footings. The optimum interference factor is defined at spacings of 2B and 3B for dense and loose reinforced sands, respectively. Furthermore, by including three continuous geogrid layers underneath two square footing interferences, their behaviour will be improved.","PeriodicalId":46470,"journal":{"name":"Geomechanics and Geoengineering-An International Journal","volume":"18 1","pages":"149 - 167"},"PeriodicalIF":1.3,"publicationDate":"2021-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41934620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-30DOI: 10.1080/17486025.2021.2018509
Sreelakshmi G, Asha M. N
ABSTRACT The foundation systems for bridges and marine structures demand deep foundations like hollow driven open-ended piles, where hard-bearing strata exist on deep soil underneath loose inland and oceanic sea floors. During this driving process, a soil plug is formed near the hollow pile tip region, resulting in soil crushing and compression at the pile tip. The conventional methods fail to predict such volume changes and densification of the embedded soil. The present study utilised Particle Image Velocimetry (PIV) technique to assess the plugging at the pile tip and compare the penetration rate under different infill densities. The PIV results indicated that at a specific energy, pile geometric parameters and infill conditions strongly influenced pile drivability in a granular medium. Due to disturbance caused by pile driving at the base, high compressive strains are observed for large diameter piles, while large dilative strains developed soil plug during the penetration stage for small diameter piles. The plug surface profile was concave for larger diameter piles due to active arching mechanism, while it was convex for small diameter piles due to passive arching generated by lateral soil confinement within the pile wall surface.
{"title":"Investigation of soil plug formation in hollow piles using PIV technique","authors":"Sreelakshmi G, Asha M. N","doi":"10.1080/17486025.2021.2018509","DOIUrl":"https://doi.org/10.1080/17486025.2021.2018509","url":null,"abstract":"ABSTRACT The foundation systems for bridges and marine structures demand deep foundations like hollow driven open-ended piles, where hard-bearing strata exist on deep soil underneath loose inland and oceanic sea floors. During this driving process, a soil plug is formed near the hollow pile tip region, resulting in soil crushing and compression at the pile tip. The conventional methods fail to predict such volume changes and densification of the embedded soil. The present study utilised Particle Image Velocimetry (PIV) technique to assess the plugging at the pile tip and compare the penetration rate under different infill densities. The PIV results indicated that at a specific energy, pile geometric parameters and infill conditions strongly influenced pile drivability in a granular medium. Due to disturbance caused by pile driving at the base, high compressive strains are observed for large diameter piles, while large dilative strains developed soil plug during the penetration stage for small diameter piles. The plug surface profile was concave for larger diameter piles due to active arching mechanism, while it was convex for small diameter piles due to passive arching generated by lateral soil confinement within the pile wall surface.","PeriodicalId":46470,"journal":{"name":"Geomechanics and Geoengineering-An International Journal","volume":"18 1","pages":"133 - 148"},"PeriodicalIF":1.3,"publicationDate":"2021-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44578050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-29DOI: 10.1080/17486025.2021.2019321
Patteera Petchkaew, S. Keawsawasvong, Weeradetch Tanapalungkorn, S. Likitlersuang
ABSTRACT In this paper, the seismic stability number of unsupported excavations in cohesive-frictional soil under the influence of pseudo-static seismic body forces is examined. Three-dimensional finite element limit analysis is employed to numerically solve the upper and lower bounded models of unsupported excavations. The results are represented by a dimensionless stability number which is a function of four dimensionless parameters including the excavation aspect ratio, the excavated depth ratio, the soil’s effective friction angle, and the coefficient of horizontal earthquake acceleration. For the first time in literature, the influences of a soil’s effective friction angle and the coefficient of horizontal earthquake acceleration on the mechanisms of excavation failures are examined and discussed. Also presented is a case study to demonstrate the use of the proposed seismic stability number in studying unsupported excavations in seismic risk areas.
{"title":"3D stability analysis of unsupported rectangular excavation under pseudo-static seismic body force","authors":"Patteera Petchkaew, S. Keawsawasvong, Weeradetch Tanapalungkorn, S. Likitlersuang","doi":"10.1080/17486025.2021.2019321","DOIUrl":"https://doi.org/10.1080/17486025.2021.2019321","url":null,"abstract":"ABSTRACT In this paper, the seismic stability number of unsupported excavations in cohesive-frictional soil under the influence of pseudo-static seismic body forces is examined. Three-dimensional finite element limit analysis is employed to numerically solve the upper and lower bounded models of unsupported excavations. The results are represented by a dimensionless stability number which is a function of four dimensionless parameters including the excavation aspect ratio, the excavated depth ratio, the soil’s effective friction angle, and the coefficient of horizontal earthquake acceleration. For the first time in literature, the influences of a soil’s effective friction angle and the coefficient of horizontal earthquake acceleration on the mechanisms of excavation failures are examined and discussed. Also presented is a case study to demonstrate the use of the proposed seismic stability number in studying unsupported excavations in seismic risk areas.","PeriodicalId":46470,"journal":{"name":"Geomechanics and Geoengineering-An International Journal","volume":"18 1","pages":"175 - 192"},"PeriodicalIF":1.3,"publicationDate":"2021-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43640213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：