Through a series of model tests accomplished by Particle Image Velocimetry analyses, this study presents the visualization of the displacement field of the narrow soil behind retaining structures under translational mode. The progressive development of failure mechanisms and active earth pressure are measured in the process of tests. Finite element limit analyses are supplementally carried out to investigate and verify the ultimate failure mechanism and active earth pressure acting on retaining structures as the tests. Furthermore, this study carried out parameter studies on the development of failure mechanisms and active earth pressure with different aspect ratios, inclinations of the existing structure, and backfill surface surcharge. Experimental and numerical results show a reasonable verification of each other. With the increase in backfill spacing, the failure mechanism of backfill turns from reflective shear bands into a single shear band, and the earth pressure exerted on the retaining structure increases.
{"title":"Active failure mechanism and earth pressure of narrow backfill behind retaining structures","authors":"Hao-Biao Chen, Cheng Lin, Yan-Ping Lv, Fu-Quan Chen","doi":"10.1680/jphmg.23.00042","DOIUrl":"https://doi.org/10.1680/jphmg.23.00042","url":null,"abstract":"Through a series of model tests accomplished by Particle Image Velocimetry analyses, this study presents the visualization of the displacement field of the narrow soil behind retaining structures under translational mode. The progressive development of failure mechanisms and active earth pressure are measured in the process of tests. Finite element limit analyses are supplementally carried out to investigate and verify the ultimate failure mechanism and active earth pressure acting on retaining structures as the tests. Furthermore, this study carried out parameter studies on the development of failure mechanisms and active earth pressure with different aspect ratios, inclinations of the existing structure, and backfill surface surcharge. Experimental and numerical results show a reasonable verification of each other. With the increase in backfill spacing, the failure mechanism of backfill turns from reflective shear bands into a single shear band, and the earth pressure exerted on the retaining structure increases.","PeriodicalId":48816,"journal":{"name":"International Journal of Physical Modelling in Geotechnics","volume":"10 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140836121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhiyong Liu, Jiapei Ma, Junhua Xiao, Jianfeng Xue, Fei Yang
A series of physical model tests and cyclic triaxial tests were performed on a dry sand to investigate the effects of excavating an adjacent pit on the settlement behaviour of a footing under cyclic loading. The excavation is simulated by moving a retaining wall between loading cycles in the physical model tests. The excavation induced stress disturbance on soil elements is modelled by reducing cell pressure between loading cycles in triaxial tests. The results indicate that nearby excavation leads to reduction in lateral stress in ground and therefore increases the settlement of footing in the subsequent loading cycles. However, there is no clear relationship between the settlement increment and the magnitude of wall movement, when the lateral movement of the wall is within the range of 0.1% to 0.37% of the wall height. The lateral excavation does not have great impact on the influence zone of the footings under cyclic loading. An empirical model is proposed to estimate the cyclic loading-induced strain accumulation of sand with the consideration of lateral unloading effects between loading cycles. After being validated using cyclic triaxial tests results, the proposed model is employed to predict cyclic loading-induced settlement of the footing before and after the excavation.
{"title":"Physical modelling of cyclic loading induced footing settlement with a nearby pit excavation","authors":"Zhiyong Liu, Jiapei Ma, Junhua Xiao, Jianfeng Xue, Fei Yang","doi":"10.1680/jphmg.23.00016","DOIUrl":"https://doi.org/10.1680/jphmg.23.00016","url":null,"abstract":"A series of physical model tests and cyclic triaxial tests were performed on a dry sand to investigate the effects of excavating an adjacent pit on the settlement behaviour of a footing under cyclic loading. The excavation is simulated by moving a retaining wall between loading cycles in the physical model tests. The excavation induced stress disturbance on soil elements is modelled by reducing cell pressure between loading cycles in triaxial tests. The results indicate that nearby excavation leads to reduction in lateral stress in ground and therefore increases the settlement of footing in the subsequent loading cycles. However, there is no clear relationship between the settlement increment and the magnitude of wall movement, when the lateral movement of the wall is within the range of 0.1% to 0.37% of the wall height. The lateral excavation does not have great impact on the influence zone of the footings under cyclic loading. An empirical model is proposed to estimate the cyclic loading-induced strain accumulation of sand with the consideration of lateral unloading effects between loading cycles. After being validated using cyclic triaxial tests results, the proposed model is employed to predict cyclic loading-induced settlement of the footing before and after the excavation.","PeriodicalId":48816,"journal":{"name":"International Journal of Physical Modelling in Geotechnics","volume":"31 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140204700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Senthen Amuthan Mani, Francisco da Silva Pereira, Phil Watson, Britta Bienen, M. Fraser Bransby, Han Eng Low, Carl Erbrich, Sam Ingarfield, Avi Shonberg, Michael Harte
An alternate to monopiles to support offshore wind turbines is the use of jacket structures founded on suction buckets. These foundations have been successfully deployed in recent developments and have proven to be a viable foundation concept due to their relatively fast and low-noise installation, as well as their general applicability for a wide range of soil-conditions and suitability in deeper waters. However, the behaviour of bucket foundations subject to both short- and long-term uplift loading in coarse grained soil remains an area of ongoing research. For the centrifuge testing in this project, offshore soil was provided from an Asian site – and the combination of silt size particles, water pore fluid and faster loading rates was used to replicate the drainage conditions during the loading of a full-scale bucket foundation in sand. Initial self-weight penetration of the skirts was followed by suction installation, with in-place testing then undertaken to explore both monotonic and cyclic performance. This paper presents results from the pilot testing, including the foundation response to cyclic (storm) loading applied symmetrically around an average uplift load.
{"title":"Centrifuge tests exploring the cyclic performance of suction bucket foundations in cohesionless soils","authors":"Senthen Amuthan Mani, Francisco da Silva Pereira, Phil Watson, Britta Bienen, M. Fraser Bransby, Han Eng Low, Carl Erbrich, Sam Ingarfield, Avi Shonberg, Michael Harte","doi":"10.1680/jphmg.23.00020","DOIUrl":"https://doi.org/10.1680/jphmg.23.00020","url":null,"abstract":"An alternate to monopiles to support offshore wind turbines is the use of jacket structures founded on suction buckets. These foundations have been successfully deployed in recent developments and have proven to be a viable foundation concept due to their relatively fast and low-noise installation, as well as their general applicability for a wide range of soil-conditions and suitability in deeper waters. However, the behaviour of bucket foundations subject to both short- and long-term uplift loading in coarse grained soil remains an area of ongoing research. For the centrifuge testing in this project, offshore soil was provided from an Asian site – and the combination of silt size particles, water pore fluid and faster loading rates was used to replicate the drainage conditions during the loading of a full-scale bucket foundation in sand. Initial self-weight penetration of the skirts was followed by suction installation, with in-place testing then undertaken to explore both monotonic and cyclic performance. This paper presents results from the pilot testing, including the foundation response to cyclic (storm) loading applied symmetrically around an average uplift load.","PeriodicalId":48816,"journal":{"name":"International Journal of Physical Modelling in Geotechnics","volume":"39 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140204670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-01DOI: 10.1680/jphmg.2024.24.1.1
Anthony F. Tessari
{"title":"Editorial: A new year and new advances in geotechnics","authors":"Anthony F. Tessari","doi":"10.1680/jphmg.2024.24.1.1","DOIUrl":"https://doi.org/10.1680/jphmg.2024.24.1.1","url":null,"abstract":"","PeriodicalId":48816,"journal":{"name":"International Journal of Physical Modelling in Geotechnics","volume":"17 11","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139455956","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-01DOI: 10.1680/jphmg.2024.24.1.54
{"title":"Award-winning paper in 2022","authors":"","doi":"10.1680/jphmg.2024.24.1.54","DOIUrl":"https://doi.org/10.1680/jphmg.2024.24.1.54","url":null,"abstract":"","PeriodicalId":48816,"journal":{"name":"International Journal of Physical Modelling in Geotechnics","volume":"24 12","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139455196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-01DOI: 10.1680/jphmg.2024.24.1.55
{"title":"International Journal of Physical Modelling in Geotechnics: Referees 2023","authors":"","doi":"10.1680/jphmg.2024.24.1.55","DOIUrl":"https://doi.org/10.1680/jphmg.2024.24.1.55","url":null,"abstract":"","PeriodicalId":48816,"journal":{"name":"International Journal of Physical Modelling in Geotechnics","volume":"35 38","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139455663","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Guobo Wang, Yao Wang, Jianning Wang, Zhengfang Dong
Currently, many subway stations are designed symmetrically and less attention has been paid to asymmetrical stations. The middle column of the asymmetric underground structure is offset to one side, which is not conducive to load-bearing in strong earthquakes and is prone to damage. In this study, shaking table tests of a soil-symmetrical station and a soil-asymmetrical station were designed and conducted. A numerical model of soil-structure interaction system was established, and the feasibility of the simulation method was verified. Then, the seismic responses of two kinds of stations were discussed and analyzed. The results show that the dynamic response of both symmetrical and asymmetrical stations increases with the increase of loading seismic intensity. Influenced by the size effect of the model test, there is less difference between the two models in their dynamic response. From the perspective of internal force and relative deformation, the response of asymmetrical station is greater than that of symmetrical station, which adequately reflects the disadvantage of asymmetrical structure in seismic design.
{"title":"Shaking table test on seismic responses of asymmetrical underground subway stations","authors":"Guobo Wang, Yao Wang, Jianning Wang, Zhengfang Dong","doi":"10.1680/jphmg.22.00071","DOIUrl":"https://doi.org/10.1680/jphmg.22.00071","url":null,"abstract":"Currently, many subway stations are designed symmetrically and less attention has been paid to asymmetrical stations. The middle column of the asymmetric underground structure is offset to one side, which is not conducive to load-bearing in strong earthquakes and is prone to damage. In this study, shaking table tests of a soil-symmetrical station and a soil-asymmetrical station were designed and conducted. A numerical model of soil-structure interaction system was established, and the feasibility of the simulation method was verified. Then, the seismic responses of two kinds of stations were discussed and analyzed. The results show that the dynamic response of both symmetrical and asymmetrical stations increases with the increase of loading seismic intensity. Influenced by the size effect of the model test, there is less difference between the two models in their dynamic response. From the perspective of internal force and relative deformation, the response of asymmetrical station is greater than that of symmetrical station, which adequately reflects the disadvantage of asymmetrical structure in seismic design.","PeriodicalId":48816,"journal":{"name":"International Journal of Physical Modelling in Geotechnics","volume":"160 10","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136067435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Foundations in northern climates are founded in ground conditions that are certain to change due to climate warming. Piled foundations situated in permafrost are designed to resist loads by mobilizing shaft friction from adfreeze strength that is attributed to the ice-soil bonds in contact with the pile. Design considers ground warming causing thawing over time and normally specifies a thermal condition whereby mitigation measures, such as thermosyphons, are to be implemented. While pile design and analysis for completely frozen and thawed profiles are defined in terms of pile capacity, the intermediate condition, during transition from frozen to thawed, is not well examined. In this study centrifuge modelling is utilized to quantify the reduction in pile capacity and foundation stiffness under axial monotonic loading as initially frozen sand profiles warm and thaw depth increases. The results show agreement between the physical models and analysis methods for piles in fully frozen and thawed ground. A marked decrease in pile capacity occurs as ground temperatures approach freezing and thaw depth increases. The results are the first comprehensive physical model testing program aimed at quantifying pile performance in frozen and warming ground at field realistic stress conditions.
{"title":"Centrifuge modelling of axially loaded steel piles in cold and thawing frozen sand","authors":"Chris Clarkson, Geoff Eichhorn, Greg Siemens","doi":"10.1680/jphmg.22.00062","DOIUrl":"https://doi.org/10.1680/jphmg.22.00062","url":null,"abstract":"Foundations in northern climates are founded in ground conditions that are certain to change due to climate warming. Piled foundations situated in permafrost are designed to resist loads by mobilizing shaft friction from adfreeze strength that is attributed to the ice-soil bonds in contact with the pile. Design considers ground warming causing thawing over time and normally specifies a thermal condition whereby mitigation measures, such as thermosyphons, are to be implemented. While pile design and analysis for completely frozen and thawed profiles are defined in terms of pile capacity, the intermediate condition, during transition from frozen to thawed, is not well examined. In this study centrifuge modelling is utilized to quantify the reduction in pile capacity and foundation stiffness under axial monotonic loading as initially frozen sand profiles warm and thaw depth increases. The results show agreement between the physical models and analysis methods for piles in fully frozen and thawed ground. A marked decrease in pile capacity occurs as ground temperatures approach freezing and thaw depth increases. The results are the first comprehensive physical model testing program aimed at quantifying pile performance in frozen and warming ground at field realistic stress conditions.","PeriodicalId":48816,"journal":{"name":"International Journal of Physical Modelling in Geotechnics","volume":"183 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135888273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Finned piles are considered a novel solution to replace large-diameter piles supporting transmission towers, bridge abutments and so on and are often implemented beneficially for mooring dolphins in offshore areas. This experimental investigation was attempted to examine the lateral response of short-finned piles installed in the proximity of a typical slope of 1V:2H. The 1g model testing of regular and finned piles at different load eccentricities comprised three lateral load tests on horizontal ground and 24 lateral load tests on the slope with the pile at varying distances from the crest. The fin efficiency was observed to decrease with an increase in load eccentricity due to the poorer mobilisation of soil resistance on fins at higher load eccentricities. The finned pile installed at a distance of two pile diameters away from the crest exhibited a net efficiency closer to unity, indicating its ability to improve the receptible subgrade reaction near a loose and steeper sandy slope. An in-depth study of soil resistance developed in the finned pile located at the crest reveals that the fins effectively reduced the soil resistance, specifically in the region above the pivot point.
{"title":"Behaviour of a laterally loaded short-finned pile located on sloping ground","authors":"K. T. Krishnanunni, Deendayal Rathod","doi":"10.1680/jphmg.23.00011","DOIUrl":"https://doi.org/10.1680/jphmg.23.00011","url":null,"abstract":"Finned piles are considered a novel solution to replace large-diameter piles supporting transmission towers, bridge abutments and so on and are often implemented beneficially for mooring dolphins in offshore areas. This experimental investigation was attempted to examine the lateral response of short-finned piles installed in the proximity of a typical slope of 1V:2H. The 1g model testing of regular and finned piles at different load eccentricities comprised three lateral load tests on horizontal ground and 24 lateral load tests on the slope with the pile at varying distances from the crest. The fin efficiency was observed to decrease with an increase in load eccentricity due to the poorer mobilisation of soil resistance on fins at higher load eccentricities. The finned pile installed at a distance of two pile diameters away from the crest exhibited a net efficiency closer to unity, indicating its ability to improve the receptible subgrade reaction near a loose and steeper sandy slope. An in-depth study of soil resistance developed in the finned pile located at the crest reveals that the fins effectively reduced the soil resistance, specifically in the region above the pivot point.","PeriodicalId":48816,"journal":{"name":"International Journal of Physical Modelling in Geotechnics","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135923900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Leonardo Maria Lalicata, Eric Ritchie, Sarah Elizabeth Stallebrass, Andrew McNamara
A novel experimental technology for small scale centrifuge tests on piled foundations has been investigated. The technology is suitable for bored piles where the pile shaft has been profiled to improve the bearing capacity. One such pile is an impression pile that has an enhanced shaft capacity due to the small impressions created along the shaft. In previous centrifuge testing, impression piles have been created by pouring resin into a profiled bore. However, in the technique to be described a novel pile made of 3D printed rigid plastic with a reverse mandrel mechanism is used to create a nodular shaft surface during installation in the clay sample. Once assembled the pile has the same geometry as the cast in situ impression pile. Compared to the resin piles, 3D printed plastic piles allow for faster model making and demonstrate excellent repeatability. Because of the ductile behaviour of the soil-plastic interface it is possible to see how the impressions improve the performance of a pile over the whole load-settlement curve, not just at ultimate capacity. In addition, a greater percentage increase in ultimate capacity was registered for the 3D printed plastic impression piles compared to similar resin impression piles. The plastic-soil interface has an α value which is closer to that commonly encountered in the field. At working load, the 3D printed plastic impression piles outperformed traditional straight shafted piles by 90%.
{"title":"A novel experimental technique to model impression piles in centrifuge testing","authors":"Leonardo Maria Lalicata, Eric Ritchie, Sarah Elizabeth Stallebrass, Andrew McNamara","doi":"10.1680/jphmg.22.00065","DOIUrl":"https://doi.org/10.1680/jphmg.22.00065","url":null,"abstract":"A novel experimental technology for small scale centrifuge tests on piled foundations has been investigated. The technology is suitable for bored piles where the pile shaft has been profiled to improve the bearing capacity. One such pile is an impression pile that has an enhanced shaft capacity due to the small impressions created along the shaft. In previous centrifuge testing, impression piles have been created by pouring resin into a profiled bore. However, in the technique to be described a novel pile made of 3D printed rigid plastic with a reverse mandrel mechanism is used to create a nodular shaft surface during installation in the clay sample. Once assembled the pile has the same geometry as the cast in situ impression pile. Compared to the resin piles, 3D printed plastic piles allow for faster model making and demonstrate excellent repeatability. Because of the ductile behaviour of the soil-plastic interface it is possible to see how the impressions improve the performance of a pile over the whole load-settlement curve, not just at ultimate capacity. In addition, a greater percentage increase in ultimate capacity was registered for the 3D printed plastic impression piles compared to similar resin impression piles. The plastic-soil interface has an α value which is closer to that commonly encountered in the field. At working load, the 3D printed plastic impression piles outperformed traditional straight shafted piles by 90%.","PeriodicalId":48816,"journal":{"name":"International Journal of Physical Modelling in Geotechnics","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136356835","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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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