Juliano A. Nietiedt, Mark F. Randolph, Christophe Gaudin, James P. Doherty
The offshore wind industry continues to expand rapidly around the world in response to demand for clean energy. Research to investigate monopile performance under cyclic lateral loading needs to replicate the installation process as well as the cyclic loading regimes. This has provided the impetus for the development of model pile driving hammers for use in geotechnical centrifuges. The paper presents a new model-scale centrifuge impact-hammer that is capable of in-flight driving of large diameter piles into dense sediments with the flexibility of varying energy during a test for a more controlled installation. The new hammer is activated by a pair of rotating cams, improving on the pneumatically activated hammer developed in the 1980s, giving greater energy and much better reliability. This paper provides full details of the hammer, together with data obtained at 80 g acceleration, driving prototype 4 m diameter (50 mm in model scale) piles into dense dry sand to depths of over 20 m (over 5 diameters) in less than 1000 blows
{"title":"Development of a high-energy centrifuge model pile hammer for impact-driving large diameter piles","authors":"Juliano A. Nietiedt, Mark F. Randolph, Christophe Gaudin, James P. Doherty","doi":"10.1680/jphmg.21.00096","DOIUrl":"https://doi.org/10.1680/jphmg.21.00096","url":null,"abstract":"The offshore wind industry continues to expand rapidly around the world in response to demand for clean energy. Research to investigate monopile performance under cyclic lateral loading needs to replicate the installation process as well as the cyclic loading regimes. This has provided the impetus for the development of model pile driving hammers for use in geotechnical centrifuges. The paper presents a new model-scale centrifuge impact-hammer that is capable of in-flight driving of large diameter piles into dense sediments with the flexibility of varying energy during a test for a more controlled installation. The new hammer is activated by a pair of rotating cams, improving on the pneumatically activated hammer developed in the 1980s, giving greater energy and much better reliability. This paper provides full details of the hammer, together with data obtained at 80 g acceleration, driving prototype 4 m diameter (50 mm in model scale) piles into dense dry sand to depths of over 20 m (over 5 diameters) in less than 1000 blows","PeriodicalId":48816,"journal":{"name":"International Journal of Physical Modelling in Geotechnics","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135815489","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}
Assembled multi-step cantilever retaining walls is a new type of light retaining structure, which can be quickly installed in situ and suitable for high fill earthworks. In order to investigate its mechanical behaviors fully to support practical analysis and design of the novel wall, a series of laboratory model tests are conducted for three-step cantilever walls retaining cohesionless filling under various strip surcharges on the top of the backfill. Test results indicate that lateral earth pressure on the highest-step wall member increases with the depth on the upper two-thirds segment of the wall stem, whereas it presents multi-step polyline distribution mode on the lower two steps. Except for the highest-step wall member, the earth pressure on the upper part of each member stem shows some reduction effect due to shielding action of the upper heel plate inserted in the backfill. The lateral earth pressure on the wall obtained by numerical simulation via FLAC3D is consistent with the measured one in terms of the whole variation tendency. Horizontal displacement of the whole wall takes on a unimodal profile with relatively higher values at the middle height of the wall. Increasing the bench width is helpful to reduce the lateral earth pressure on the wall stems and setting up shear key beneath the footing plate of the lowest-step member can reduce the wall displacement by up to 51%.
{"title":"Static model tests on mechanical behavior of assembled multi-step cantilever walls","authors":"Zhaoying Li, Shiguo Xiao","doi":"10.1680/jphmg.22.00076","DOIUrl":"https://doi.org/10.1680/jphmg.22.00076","url":null,"abstract":"Assembled multi-step cantilever retaining walls is a new type of light retaining structure, which can be quickly installed in situ and suitable for high fill earthworks. In order to investigate its mechanical behaviors fully to support practical analysis and design of the novel wall, a series of laboratory model tests are conducted for three-step cantilever walls retaining cohesionless filling under various strip surcharges on the top of the backfill. Test results indicate that lateral earth pressure on the highest-step wall member increases with the depth on the upper two-thirds segment of the wall stem, whereas it presents multi-step polyline distribution mode on the lower two steps. Except for the highest-step wall member, the earth pressure on the upper part of each member stem shows some reduction effect due to shielding action of the upper heel plate inserted in the backfill. The lateral earth pressure on the wall obtained by numerical simulation via FLAC3D is consistent with the measured one in terms of the whole variation tendency. Horizontal displacement of the whole wall takes on a unimodal profile with relatively higher values at the middle height of the wall. Increasing the bench width is helpful to reduce the lateral earth pressure on the wall stems and setting up shear key beneath the footing plate of the lowest-step member can reduce the wall displacement by up to 51%.","PeriodicalId":48816,"journal":{"name":"International Journal of Physical Modelling in Geotechnics","volume":"1 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41412281","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}
Longhua Guan, Fengkui Zhao, Qiang Lu, Jun-chao Li, Yubing Wang, B. Zhu, Dezhi Zhang
Centrifuge model tests are performed to investigate the dynamic response of dry sand under blast loading. The characteristics and propagation mode of blast waves in dry sand are studied. The Coriolis effect on blast-induced cratering is carefully scrutinized, and both the theoretical and experimental results are provided and agree with each other. In the explosion-induced cratering process, the sand ejecta is subjected to horizontal and vertical Coriolis forces simultaneously; the former directly determines the horizontal motion offset, while the latter affects the particle motion by altering the flight time, and the Coriolis effect on cratering can only be observed apparently for soil ejecta with a relatively small launch angle. Redistribution of the static earth pressure (blast-induced arching effect) in deep-buried, fully confined explosion events under hypergravity is observed. The friction between sand particles is significantly enhanced by the hypergravity to serve as the supporting arch springing. Conceptual analysis is conducted to further reveal the mechanism of the blast-induced arching effect based on the trapdoor test from three aspects of displacement mode, stress development, and post-detonation stress distribution.
{"title":"Geotechnical centrifuge modelling of blast effects in dry sand: Coriolis effect and soil arching","authors":"Longhua Guan, Fengkui Zhao, Qiang Lu, Jun-chao Li, Yubing Wang, B. Zhu, Dezhi Zhang","doi":"10.1680/jphmg.22.00068","DOIUrl":"https://doi.org/10.1680/jphmg.22.00068","url":null,"abstract":"Centrifuge model tests are performed to investigate the dynamic response of dry sand under blast loading. The characteristics and propagation mode of blast waves in dry sand are studied. The Coriolis effect on blast-induced cratering is carefully scrutinized, and both the theoretical and experimental results are provided and agree with each other. In the explosion-induced cratering process, the sand ejecta is subjected to horizontal and vertical Coriolis forces simultaneously; the former directly determines the horizontal motion offset, while the latter affects the particle motion by altering the flight time, and the Coriolis effect on cratering can only be observed apparently for soil ejecta with a relatively small launch angle. Redistribution of the static earth pressure (blast-induced arching effect) in deep-buried, fully confined explosion events under hypergravity is observed. The friction between sand particles is significantly enhanced by the hypergravity to serve as the supporting arch springing. Conceptual analysis is conducted to further reveal the mechanism of the blast-induced arching effect based on the trapdoor test from three aspects of displacement mode, stress development, and post-detonation stress distribution.","PeriodicalId":48816,"journal":{"name":"International Journal of Physical Modelling in Geotechnics","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47314397","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}
Contact erosion, or interfacial erosion, often occurs in layered foundations composed of coarse and fine layers, which refers to the phenomenon that the particles of the fine layer are detached by the flow parallel to the interface and transported through the pore channels of the coarse layer. In order to visualize the initiation and progression of contact erosion at the internal interface of soil strata, the transparent soil model tests were employed to simulate the real soil, and a series of contact erosion tests were conducted on double-layer foundations composed of different coarse and fine layers. Based on the test results, the commonly used geometric and hydraulic criteria for contact erosion were examined. It shows that the geometric criteria are reliable, while hydraulic criteria give much diverse results. For the same fine soil layer, the critical hydraulic gradient varies greatly with the coarse soil layer, while the critical flow velocity varies in a relatively small range since flow velocity has an intrinsic relationship with the dragging force imposed on particles by seepage flow. It is suggested that more efforts should be paid to the criteria based on critical velocity in further studies for contact erosion.
{"title":"Examining the criteria for contact erosion in granular soil foundations through transparent soil model tests","authors":"G. Wang, Jing Yang, W. Jin, Z. Deng, Zihao Zhang","doi":"10.1680/jphmg.22.00064","DOIUrl":"https://doi.org/10.1680/jphmg.22.00064","url":null,"abstract":"Contact erosion, or interfacial erosion, often occurs in layered foundations composed of coarse and fine layers, which refers to the phenomenon that the particles of the fine layer are detached by the flow parallel to the interface and transported through the pore channels of the coarse layer. In order to visualize the initiation and progression of contact erosion at the internal interface of soil strata, the transparent soil model tests were employed to simulate the real soil, and a series of contact erosion tests were conducted on double-layer foundations composed of different coarse and fine layers. Based on the test results, the commonly used geometric and hydraulic criteria for contact erosion were examined. It shows that the geometric criteria are reliable, while hydraulic criteria give much diverse results. For the same fine soil layer, the critical hydraulic gradient varies greatly with the coarse soil layer, while the critical flow velocity varies in a relatively small range since flow velocity has an intrinsic relationship with the dragging force imposed on particles by seepage flow. It is suggested that more efforts should be paid to the criteria based on critical velocity in further studies for contact erosion.","PeriodicalId":48816,"journal":{"name":"International Journal of Physical Modelling in Geotechnics","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41495971","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}
Compared with raft foundations, piled raft foundations can effectively reduce settlements caused by external loads such as superstructures, which makes them play an important role in constructions in urban areas. Recently, with the development of new piling methods, steel sheet piles can be penetrated into various types of grounds with high quality and precision. Although piles for piled raft foundations are usually pipe piles, sheet piles could become an alternative because the construction time and cost of sheet piles could be lower than those of pipe piles. Hence, a target of this research is to demonstrate the possibility of using sheet piles for piled raft foundations. In this study, a series of model tests were conducted first to investigate the load transfer behaviours of model piled raft foundations supported by three types of piles in an air-dried sand ground. Two of them were composed of sheet piles, called plate piles, and box pile respectively, and the other was a conventional pipe pile for comparison. Both vertical and horizontal load tests were conducted, and the load sharing between the raft and piles was carefully investigated. Since the plate pile foundation exhibited outstanding behaviours, finite element method (FEM) numerical analyses were then conducted to investigate the foundation-soil interaction in plate pile foundations under vertical and horizontal loading. According to the test and calculated results, a piled raft foundation supported by sheet piles would be a promising alternative to a conventional pipe pile foundation, especially in highly-seismic areas.
{"title":"Vertical and horizontal bearing characteristics of model piled raft foundations supported by sheet piles","authors":"X. Xiong, Wentao Guo, Tatsunori Matsumoto, Yukihiro Ishihara","doi":"10.1680/jphmg.22.00053","DOIUrl":"https://doi.org/10.1680/jphmg.22.00053","url":null,"abstract":"Compared with raft foundations, piled raft foundations can effectively reduce settlements caused by external loads such as superstructures, which makes them play an important role in constructions in urban areas. Recently, with the development of new piling methods, steel sheet piles can be penetrated into various types of grounds with high quality and precision. Although piles for piled raft foundations are usually pipe piles, sheet piles could become an alternative because the construction time and cost of sheet piles could be lower than those of pipe piles. Hence, a target of this research is to demonstrate the possibility of using sheet piles for piled raft foundations. In this study, a series of model tests were conducted first to investigate the load transfer behaviours of model piled raft foundations supported by three types of piles in an air-dried sand ground. Two of them were composed of sheet piles, called plate piles, and box pile respectively, and the other was a conventional pipe pile for comparison. Both vertical and horizontal load tests were conducted, and the load sharing between the raft and piles was carefully investigated. Since the plate pile foundation exhibited outstanding behaviours, finite element method (FEM) numerical analyses were then conducted to investigate the foundation-soil interaction in plate pile foundations under vertical and horizontal loading. According to the test and calculated results, a piled raft foundation supported by sheet piles would be a promising alternative to a conventional pipe pile foundation, especially in highly-seismic areas.","PeriodicalId":48816,"journal":{"name":"International Journal of Physical Modelling in Geotechnics","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43407908","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}
This paper presents a centrifuge study on the performance of inclined geofoam barriers compared to vertical geofoam barrier for the mitigation of ground vibrations induced by high-speed railways. Three different barrier inclinations (60°, 90° and 120°) are used in three centrifuge models. Each centrifuge model is tested for seven different frequencies. Therefore, the results of 21 centrifuge tests are reported in this paper. The results show that the barrier efficiency of inclined barriers is more than vertical barrier efficiency for the points located behind the barrier. However, for the point located before the barrier, the barrier efficiency reduces by using inclined barriers instead of the vertical barrier. The results also illustrate that the barrier efficiencies for two inclined barriers used in this research, which have supplementary angles, are almost the same.
{"title":"Centrifuge modeling of ground vibrations mitigation by inclined geofoam barrier","authors":"H. Shahnazari, M. Kazemi, M. Baziar","doi":"10.1680/jphmg.22.00032","DOIUrl":"https://doi.org/10.1680/jphmg.22.00032","url":null,"abstract":"This paper presents a centrifuge study on the performance of inclined geofoam barriers compared to vertical geofoam barrier for the mitigation of ground vibrations induced by high-speed railways. Three different barrier inclinations (60°, 90° and 120°) are used in three centrifuge models. Each centrifuge model is tested for seven different frequencies. Therefore, the results of 21 centrifuge tests are reported in this paper. The results show that the barrier efficiency of inclined barriers is more than vertical barrier efficiency for the points located behind the barrier. However, for the point located before the barrier, the barrier efficiency reduces by using inclined barriers instead of the vertical barrier. The results also illustrate that the barrier efficiencies for two inclined barriers used in this research, which have supplementary angles, are almost the same.","PeriodicalId":48816,"journal":{"name":"International Journal of Physical Modelling in Geotechnics","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41763084","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}
Badr Ouzzine, Jean de Sauvage, G. Madabhushi, Giulia M. B. Viggiani, P. Reiffsteck
For several decades, energy piles have been developed to extract heat from the ground by using foundation piles as heat exchangers. However, the thermal loading of these piles directly affects their mechanical behaviour. Centrifuge modelling of a thermally loaded pile group within a groundwater flow makes it possible to improve the understanding of the hydro-thermo-mechanical behaviour of this type of foundation. In this research groundwater flow was established in a centrifuge model to study an energy pile group. The focus of this study is to enhance the research on energy geo-structures such as foundations which are very often located in soil with seepage. The groundwater flow allows reducing the thermomechanical effects and therefore plays the role as a stress and deformation stabiliser in addition to favouring the thermal recharge of the soil.
{"title":"Centrifuge modelling of an energy pile group with ground water flow","authors":"Badr Ouzzine, Jean de Sauvage, G. Madabhushi, Giulia M. B. Viggiani, P. Reiffsteck","doi":"10.1680/jphmg.22.00041","DOIUrl":"https://doi.org/10.1680/jphmg.22.00041","url":null,"abstract":"For several decades, energy piles have been developed to extract heat from the ground by using foundation piles as heat exchangers. However, the thermal loading of these piles directly affects their mechanical behaviour. Centrifuge modelling of a thermally loaded pile group within a groundwater flow makes it possible to improve the understanding of the hydro-thermo-mechanical behaviour of this type of foundation. In this research groundwater flow was established in a centrifuge model to study an energy pile group. The focus of this study is to enhance the research on energy geo-structures such as foundations which are very often located in soil with seepage. The groundwater flow allows reducing the thermomechanical effects and therefore plays the role as a stress and deformation stabiliser in addition to favouring the thermal recharge of the soil.","PeriodicalId":48816,"journal":{"name":"International Journal of Physical Modelling in Geotechnics","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46443118","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}
The paper describes the methods and outcomes of tests designed to simulate the penetration of a pushed in model pile, or a field testing penetration element. The penetration element was a 25 mm diameter cylinder with a conical tip. The element was advanced into a sand profile subjected to vertical pressure under at-rest conditions. The unique aspect of the testing was the inclusion of in-soil measurement tools. Null soil pressure gages were used to monitor radial pressures and in-soil linear strain devices were used to monitor radial strain at points within a measurement horizon as the penetration element was advanced into the profile. Testing revealed that radial pressures return to their ambient pre-penetration magnitudes once the element passes below a sensing horizon. In-soil radial strain measurements illustrated that the rapid drop in radial soil pressure coincides with a small, but consistent reversal in the increment of radial strain. As distance from the axis of penetration decreases this reversal is more significant. These observations have importance in considering the development of frictional resistance and axial capacity of pushed in piles and at the same time has relevance to the analysis of cone penetration testing in the determination of rational material properties.
{"title":"Measurement of stresses and strains around a pushed in model pile or cone penetrometer","authors":"M. Talesnick, Itamar Omer","doi":"10.1680/jphmg.22.00056","DOIUrl":"https://doi.org/10.1680/jphmg.22.00056","url":null,"abstract":"The paper describes the methods and outcomes of tests designed to simulate the penetration of a pushed in model pile, or a field testing penetration element. The penetration element was a 25 mm diameter cylinder with a conical tip. The element was advanced into a sand profile subjected to vertical pressure under at-rest conditions. The unique aspect of the testing was the inclusion of in-soil measurement tools. Null soil pressure gages were used to monitor radial pressures and in-soil linear strain devices were used to monitor radial strain at points within a measurement horizon as the penetration element was advanced into the profile. Testing revealed that radial pressures return to their ambient pre-penetration magnitudes once the element passes below a sensing horizon. In-soil radial strain measurements illustrated that the rapid drop in radial soil pressure coincides with a small, but consistent reversal in the increment of radial strain. As distance from the axis of penetration decreases this reversal is more significant. These observations have importance in considering the development of frictional resistance and axial capacity of pushed in piles and at the same time has relevance to the analysis of cone penetration testing in the determination of rational material properties.","PeriodicalId":48816,"journal":{"name":"International Journal of Physical Modelling in Geotechnics","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44334496","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}
One of the most significant factors affecting the efficiency of jet grouting operation is the diameter of the constructed column, which depends on soil properties, stress state, and operating parameters, including grout pressure (P), grout flow rate (Q), monitor rotational speed (ω) and lifting step (▵s). Treatment efficiency is to gain a larger diameter with specific energy applied per unit length of the column. In this study, a number of full-scale and small-scale single-fluid jet grouting elements were constructed in the field and laboratory to investigate the effects of the main operating parameters on the diameter and treatment efficiency of the columns constructed in silty sand. Furthermore, measured values and obtained trends were controlled by a comprehensive equation commonly used to predict the diameter of jet grouting columns. Results indicate that an increase in the time interval per step (▵t) and grout pressure (P), as well as a decrease in the lifting step (▵s) causes a larger column diameter and lower treatment efficiency. However, a decline in rotational speed (ω) improve both diameter and efficiency. Subsequently, the well-known equation has been modified by taking into account field measurements in this study to predict more accurate values and trends for both full-scale and small-scale jet grouting elements.
{"title":"Experimental and field investigation to enhance prediction of jet grouting column diameter and efficiency in silty sand","authors":"A. Ghodrati, M. Sabermahani, A. H. Korayem","doi":"10.1680/jphmg.21.00075","DOIUrl":"https://doi.org/10.1680/jphmg.21.00075","url":null,"abstract":"One of the most significant factors affecting the efficiency of jet grouting operation is the diameter of the constructed column, which depends on soil properties, stress state, and operating parameters, including grout pressure (P), grout flow rate (Q), monitor rotational speed (ω) and lifting step (▵s). Treatment efficiency is to gain a larger diameter with specific energy applied per unit length of the column. In this study, a number of full-scale and small-scale single-fluid jet grouting elements were constructed in the field and laboratory to investigate the effects of the main operating parameters on the diameter and treatment efficiency of the columns constructed in silty sand. Furthermore, measured values and obtained trends were controlled by a comprehensive equation commonly used to predict the diameter of jet grouting columns. Results indicate that an increase in the time interval per step (▵t) and grout pressure (P), as well as a decrease in the lifting step (▵s) causes a larger column diameter and lower treatment efficiency. However, a decline in rotational speed (ω) improve both diameter and efficiency. Subsequently, the well-known equation has been modified by taking into account field measurements in this study to predict more accurate values and trends for both full-scale and small-scale jet grouting elements.","PeriodicalId":48816,"journal":{"name":"International Journal of Physical Modelling in Geotechnics","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49619096","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}
Geotechnical structures such as levees, dikes, canals and tailing dams, when subjected to extreme climatic conditions, such as flooding and drawdown, are prone to failure on the upstream and downstream sides due to transient seepage conditions. Therefore, it is imperative to physically replicate such conditions in the actual stress state to understand the performance of these geotechnical structures. Hence, the objective of this paper is to present the performance of an in-flight simulator developed to simulate flooding and drawdown (ISFD) events at enhanced gravities. The working principle, design details, various components of the developed simulator, and calibration at normal (1g) and high gravities are discussed. In the present study, the calibration and performance of the ISFD setup were demonstrated on a model levee section in a 4.5 m radius large beam geotechnical centrifuge facility available at the Indian Institute of Technology Bombay, India. The rate of flooding and drawdown varied from 2.2 m/day to 7 m/day and 1.65 m/day to 4.4 m/day (in prototype dimensions), respectively, obtained with the help of pore-water pressure transducers placed on the upstream and downstream sides of the levee section. A total of three centrifuge model tests were conducted on a scaled-down levee section (with and without internal drainage layers) constructed with silty sand type material to validate the ISFD capabilities. In addition, seepage and slope stability analysis for the centrifuge models was carried out using Plaxis-2D geotechnical software which compared favourably with physically observed tests results.
{"title":"Design and development of an in-flight simulator for flooding and drawdown in a geotechnical centrifuge","authors":"B. Viswanadham, R. Saran, Pankaj Kumar","doi":"10.1680/jphmg.21.00093","DOIUrl":"https://doi.org/10.1680/jphmg.21.00093","url":null,"abstract":"Geotechnical structures such as levees, dikes, canals and tailing dams, when subjected to extreme climatic conditions, such as flooding and drawdown, are prone to failure on the upstream and downstream sides due to transient seepage conditions. Therefore, it is imperative to physically replicate such conditions in the actual stress state to understand the performance of these geotechnical structures. Hence, the objective of this paper is to present the performance of an in-flight simulator developed to simulate flooding and drawdown (ISFD) events at enhanced gravities. The working principle, design details, various components of the developed simulator, and calibration at normal (1g) and high gravities are discussed. In the present study, the calibration and performance of the ISFD setup were demonstrated on a model levee section in a 4.5 m radius large beam geotechnical centrifuge facility available at the Indian Institute of Technology Bombay, India. The rate of flooding and drawdown varied from 2.2 m/day to 7 m/day and 1.65 m/day to 4.4 m/day (in prototype dimensions), respectively, obtained with the help of pore-water pressure transducers placed on the upstream and downstream sides of the levee section. A total of three centrifuge model tests were conducted on a scaled-down levee section (with and without internal drainage layers) constructed with silty sand type material to validate the ISFD capabilities. In addition, seepage and slope stability analysis for the centrifuge models was carried out using Plaxis-2D geotechnical software which compared favourably with physically observed tests results.","PeriodicalId":48816,"journal":{"name":"International Journal of Physical Modelling in Geotechnics","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44894234","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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