The Experts below are selected from a list of 219 Experts worldwide ranked by ideXlab platform
M W Bo - One of the best experts on this subject based on the ideXlab platform.
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Factors Affecting Consolidation Related Prediction of Singapore Marine Clay by Observational Methods
Geotechnical and Geological Engineering, 2008Co-Authors: Arul Arulrajah, M W BoAbstract:The use of prefabricated vertical drains with preloading option is the most widely-used Ground Improvement Method for the Improvement of marine clays in land reclamation projects. The assessment of the degree of consolidation of the marine clay is of paramount importance prior to the removal of preload in such Ground Improvement projects. This analysis can be carried out by means of observational Methods with the use of field settlement plates and piezometer monitoring. Field settlement monitoring data can be used to ascertain the settlement of the reclaimed fill from the time of initial installation. The field settlement data can be analysed by the Asaoka Method to predict the ultimate settlement of the reclaimed land under the surcharge fill. Back-analysis of the field settlement data will enable the coefficient of consolidation due to horizontal flow to be closely estimated. Piezometer monitoring data can be analysed to obtain the degree of consolidation of the improved marine clay. Back-analysis of the piezometer data will also enable the coefficient of consolidation due to horizontal flow to be estimated. The aim of this paper is to highlight the significance and impact of the various factors that affect prediction by the Asaoka and piezometer assessment Methods. The authors findings of the Asaoka Method reveal that the magnitude of ultimate settlement decreases and the degree of consolidation subsequently increases as a longer period of assessment is used in the prediction. The degree of consolidation predicted by the piezometers is found to be in good agreement with the Asaoka Method for the early period of assessment. However as the assessment period increases, the piezometer indicates lower degree of consolidation as compared to field settlement predictions.
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Factors affecting field instrumentation assessment of marine clay treated with prefabricated vertical drains
Geotextiles and Geomembranes, 2004Co-Authors: Arul Arulrajah, Hamid Nikraz, M W BoAbstract:Abstract The use of prefabricated vertical drains with preloading option is the most widely-used Ground Improvement Method for the Improvement of soft clays in land reclamation projects. Surcharge of equivalent working load after taking into account submergence effect and settlement of the reclaimed land is placed until the required degree of consolidation of the soft clay is obtained. The assessment of the degree of consolidation of the marine clay is of paramount importance prior to the removal of preload. This analysis can be carried out by means of observational Methods with the use of field settlement plates and piezometer monitoring. Field settlement monitoring data can be used to ascertain the settlement of the reclaimed fill from the time of initial installation. The field settlement data can be analysed by the Asaoka and Hyperbolic Methods to predict the ultimate settlement of the reclaimed land under the surcharge fill. Back-analysis of the field settlement data by the Asaoka Method will enable the coefficient of consolidation due to horizontal flow to be closely estimated. Piezometer monitoring data can be analysed to obtain the degree of consolidation of the improved marine clay. Back-analysis of the piezometer data will also enable the coefficient of consolidation due to horizontal flow to be estimated. The authors’ findings of the Asaoka Method reveal that the magnitude of ultimate settlement decreases and the degree of consolidation subsequently increases as a longer period of assessment is used in the prediction. It is apparent that as the time interval increases, a cut-off time interval is obtained after which increasing time intervals would converge to the same magnitude of ultimate settlement. The authors’ findings of the Hyperbolic Method reveal that the magnitude of ultimate settlement increases and subsequently the degree of consolidation decreases as a longer period of assessment is used in the prediction. The degree of consolidation predicted by the piezometers is found to be in good agreement with the Asaoka and Hyperbolic Methods for the early period of assessment. However as the assessment period increases, the piezometer indicates lower degree of consolidation as compared to field settlement predictions. The aim of this paper is to highlight the significance and influence of various factors that affect predictions by the Asaoka, Hyperbolic and piezometer assessment Methods.
Makoto Kimura - One of the best experts on this subject based on the ideXlab platform.
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Centrifuge model tests on pore water pressure combined with vacuum and embankment loading
International Journal of Physical Modelling in Geotechnics, 2020Co-Authors: Yasuo Sawamura, Shinichiro Shiraga, Genki Hasegawa, Makoto KimuraAbstract:Vacuum consolidation is a Ground-Improvement Method in which negative pressure is applied to drain materials placed in a soft Ground to consolidate the Ground. Using the vacuum consolidation Method...
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Discussion on the mechanism of Ground Improvement Method at the excavation of shallow overburden tunnel in difficult Ground
Underground Space, 2016Co-Authors: Kiyoshi Kishida, Ying Cui, Masaichi Nonomura, Tomomi Iura, Makoto KimuraAbstract:Abstract Tunnel construction opportunities involving shallow overburdens under difficult (e.g., soft, unconsolidated) Grounds have been increasing in Japan. Various auxiliary Methods for excavating mountain tunnels have been developed and can satisfy stringent construction requirements. The Ground Improvement Method, which is one of the auxiliary Methods for shallow overburden tunnels, has demonstrated its ability to effectively control the amount of settlement under soft Ground. However, the mechanism of the Ground Improvement Method has not been clarified, nor has a suitable design code been established for it. Therefore, because the strength of the improved Ground and the suitable length and width of the improved area have not been fully understood, an empirical design has been applied in every case. In this paper, the mechanical behavior during the excavation, including that of the stabilized Ground, is evaluated through trapdoor experiments and numerical analyses. In addition, the enhancement of tunnel stability resulting from the application of the Ground Improvement Method is discussed.
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ANALYTICAL SUDY ON THE EFFECT OF PRE-Ground Improvement Method DURING SHALLOW TUNNEL EXCAVATION IN SANDY Ground
Journal of Japan Society of Civil Engineers, 2012Co-Authors: Ying Cui, Kiyoshi Kishida, Masaichi Nonomura, Tomomi Iura, Makoto KimuraAbstract:During the construction of the Tohoku and the Hokuriku Bullet Train lines, several shallow tunnels were excavated in unconsolidated Grounds using the New Austrian Tunneling Method (NATM). In order to prevent settlements of Ground tunnel and to ensure the stabilization of the cutting face of the tunnels, Ground Improvement was carried out in the above-mentioned fields. In the construction areas where the aboveGround parts were unrestricted, the Ground around the tunnels was improved by mixing in cement before the tunnel excavations; and thereafter, the tunnels were excavated using NATM. Various combinations of improved areas and levels of strength were tried in the fields, and the tunnels were excavated successfully. However, the mechanism of the effect of the Ground Improvement Method and the influence of the improved strength, depth and width of the improved areas are not clearly understood. In this study, 2D elasto-plastic finite element analyses are carried out to clarify the mechanism of the Ground Improvement Method. The results of the numerical studies indicate that the Ground Improvement Method used here can effectively prevent the settlement of the Ground, as well as the settlement of the crown and the foot to the tunnel, by reinforcing the Ground around the tunnel, and that the Method becomes even more effective when the width of the improved areas are increased.
Arul Arulrajah - One of the best experts on this subject based on the ideXlab platform.
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Research oriented Ground Improvement projects in Changi, Singapore
2018Co-Authors: Arul Arulrajah, Victor Choa, Suksun HorpibulsukAbstract:The Changi East Reclamation projects in Singapore were implemented under 5 Phases commencing from 1991 and completed in 2005 with one phase to another has several of years of overlapping. The total implementation period was 15 years including maintenance. The Phases are named as Phase 1A, 1B, 1C, Area A (North) and Area A (South). Each Phase took about 5 to 6 years to implement. Due to the involvement of large area fills in the form of land reclamation with as thick as nearly 20 meters of hydraulic fills over up to 40 meters thickness of compressible marine clay, significant challenges were present to the geotechnical engineers on geotechnical issues such as slope stability, consolidation settlement and liquefaction potential. Due to the excessive magnitude of settlement likely to occur over a long period of duration caused by consolidation process, extensively large area was required to improve applying Ground Improvement Methods to accelerate the consolidation process. Therefore, a good design of accelerating consolidation process by applying Ground Improvement Method was deemed necessary. Many combinations of pilot tests were implemented to verify the design of Ground Improvement works. In addition to improving the underlying soils, Improvement was also required for the fills which were loosely deposited by means of hydraulic filling techniques. In order to be able to successfully implement these complex projects, applying the most up to date state of the art technologies, implementation of research level planning, investigation, design and implementation processes were required throughout the projects from master planning stage to commissioning stage. Several forms of performance monitoring using geotechnical instrumentation, verification of achieving specified Improvement using intermediate and post Improvement Ground investigation and in-situ testing were implemented during and acceptance of Ground Improvement works. Quality control and assurance tests of material delivered and used for Ground Improvement were carried out throughout the implementation process. This paper presents how research oriented Ground Improvement projects were implemented in the past decade in Singapore.
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Factors Affecting Consolidation Related Prediction of Singapore Marine Clay by Observational Methods
Geotechnical and Geological Engineering, 2008Co-Authors: Arul Arulrajah, M W BoAbstract:The use of prefabricated vertical drains with preloading option is the most widely-used Ground Improvement Method for the Improvement of marine clays in land reclamation projects. The assessment of the degree of consolidation of the marine clay is of paramount importance prior to the removal of preload in such Ground Improvement projects. This analysis can be carried out by means of observational Methods with the use of field settlement plates and piezometer monitoring. Field settlement monitoring data can be used to ascertain the settlement of the reclaimed fill from the time of initial installation. The field settlement data can be analysed by the Asaoka Method to predict the ultimate settlement of the reclaimed land under the surcharge fill. Back-analysis of the field settlement data will enable the coefficient of consolidation due to horizontal flow to be closely estimated. Piezometer monitoring data can be analysed to obtain the degree of consolidation of the improved marine clay. Back-analysis of the piezometer data will also enable the coefficient of consolidation due to horizontal flow to be estimated. The aim of this paper is to highlight the significance and impact of the various factors that affect prediction by the Asaoka and piezometer assessment Methods. The authors findings of the Asaoka Method reveal that the magnitude of ultimate settlement decreases and the degree of consolidation subsequently increases as a longer period of assessment is used in the prediction. The degree of consolidation predicted by the piezometers is found to be in good agreement with the Asaoka Method for the early period of assessment. However as the assessment period increases, the piezometer indicates lower degree of consolidation as compared to field settlement predictions.
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Factors affecting field instrumentation assessment of marine clay treated with prefabricated vertical drains
Geotextiles and Geomembranes, 2004Co-Authors: Arul Arulrajah, Hamid Nikraz, M W BoAbstract:Abstract The use of prefabricated vertical drains with preloading option is the most widely-used Ground Improvement Method for the Improvement of soft clays in land reclamation projects. Surcharge of equivalent working load after taking into account submergence effect and settlement of the reclaimed land is placed until the required degree of consolidation of the soft clay is obtained. The assessment of the degree of consolidation of the marine clay is of paramount importance prior to the removal of preload. This analysis can be carried out by means of observational Methods with the use of field settlement plates and piezometer monitoring. Field settlement monitoring data can be used to ascertain the settlement of the reclaimed fill from the time of initial installation. The field settlement data can be analysed by the Asaoka and Hyperbolic Methods to predict the ultimate settlement of the reclaimed land under the surcharge fill. Back-analysis of the field settlement data by the Asaoka Method will enable the coefficient of consolidation due to horizontal flow to be closely estimated. Piezometer monitoring data can be analysed to obtain the degree of consolidation of the improved marine clay. Back-analysis of the piezometer data will also enable the coefficient of consolidation due to horizontal flow to be estimated. The authors’ findings of the Asaoka Method reveal that the magnitude of ultimate settlement decreases and the degree of consolidation subsequently increases as a longer period of assessment is used in the prediction. It is apparent that as the time interval increases, a cut-off time interval is obtained after which increasing time intervals would converge to the same magnitude of ultimate settlement. The authors’ findings of the Hyperbolic Method reveal that the magnitude of ultimate settlement increases and subsequently the degree of consolidation decreases as a longer period of assessment is used in the prediction. The degree of consolidation predicted by the piezometers is found to be in good agreement with the Asaoka and Hyperbolic Methods for the early period of assessment. However as the assessment period increases, the piezometer indicates lower degree of consolidation as compared to field settlement predictions. The aim of this paper is to highlight the significance and influence of various factors that affect predictions by the Asaoka, Hyperbolic and piezometer assessment Methods.
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factors affecting assessment and back analysis by piezometer monitoring
Australian Geomechanics: Journal of the Australian Geomechanics Society, 2004Co-Authors: Arul Arulrajah, Hamid NikrazAbstract:Prefabricated vertical drains with preloading optio n are the most widely-used Ground Improvement Method for the Improvement of marine clays in land reclamation projects. The assessment of the degree of consolidatio n of the marine clay is of paramount importance prior to the remova l of preload in such Ground Improvement projects. This analysis can be carried out by means of piezometer monitorin g. Piezometer monitoring data can be analysed to ob tain the degree of consolidation of the improved marine clay. Back -analysis of the piezometer data will also enable t he coefficient of consolidation due to horizontal flow to be estimate d. Factors that affect the analysis of piezometers include period of assessment, hydrogeologic boundary condition, settl ement of piezometer tip and reduction of initial im posed load due to submergence effect. The aim of this paper is to hig hlight the significance and impact of the various f actors that affect assessment by the piezometer monitoring Method.
Feng Zhang - One of the best experts on this subject based on the ideXlab platform.
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1-g shaking table tests on seismic enhancement of existing box culvert with partial Ground-Improvement Method and its 2D dynamic simulation
Soils and Foundations, 2018Co-Authors: Hamayoon Kheradi, Keisuke Nagano, Haruki Nishi, Feng ZhangAbstract:Abstract An underGround structure buried in a soft Ground located in a seismic-active region may experience intolerable deformation due to earthquake loading. The collapse of Daikai Station of the Kobe subway line during the 1995 Hyogoken-Nambu Earthquake demonstrated that underGround structures may also sometimes be at high risk for failure in a huge earthquake. In particular, box culverts constructed in a soft Ground with a thin overburden are vulnerable to earthquakes. Some previously constructed box culverts do not meet the present requirements of seismic design standards. In this paper, numerical analyses and 1-g shaking table tests are conducted to evaluate the effect of partial Ground Improvement (PGI) as a seismic countermeasure for the above-mentioned existing box culverts. Particular attention is paid to the optimum pattern of PGI that can most efficiently reduce the impact of an earthquake on a box culvert. The underGround structure of Daikai Station is taken as an example and its physical and geometric conditions are used to model the box culvert in the analyses and the tests. In order to accurately consider the influence of the soil-structure interaction (SSI) on the underGround structures, both the soil and the box culvert are considered in the analyses and the shaking table tests. Four different patterns of PGI are considered. Based on the analyses and the tests, an optimum pattern for the PGI of existing box culverts is proposed.
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Shaking table test on reinforcement effect of partial Ground Improvement for group-pile foundation and its numericalsimulation
Soils and Foundations, 2012Co-Authors: Xiaohua Bao, Yukihiro Morikawa, Yoshimitsu Kondo, Keisuke Nakamura, Feng ZhangAbstract:Abstract In this paper, particular attention was paid to the seismic enhancement effect of group-pile foundation with partial Ground Improvement Method that is used for existing pile foundations in practical engineering. A model test on a full system with a superstructure, a nine-pile foundation and a sandy Ground was conducted with the shaking table test device. The model pile is made from aluminum and the model Ground is made from Toyoura Sand. The shaking table test device is 120 cm in width and 160 cm in length. The maximum acceleration is 1 g and the maximum displacement is 5 cm. The maximum payload is 16 kN and the highest frequency is 10 Hz. The model Ground is carefully prepared to obtain a Ground with controllable unified density. Before the shaking table test, the pattern of the partial Ground Improvement for an existed group-pile foundation is carefully selected using numerical tests with a 3D elastoplastic static finite element analysis. In the analysis, the nonlinear behavior of Ground and piles are described by the cyclic mobility model ( Zhang et al., 2007 ) and the axial force dependent model (AFD model) proposed by Zhang and Kimura (2002) can take into consideration of axial-force dependency in the nonlinear moment–curvature relations. The applicability of the numerical analysis has been verified in previous works by comparing the numerical results with a real-scale field tests ( Kosa et al., 1998 ). Based on the results from the numerical tests on seismic enhancement effect of group-pile foundation with Ground Improvement, an optimum pattern of partial Ground Improvement of an existing pile foundations has been picked out for shaking table test. A numerical analysis using the program DBLEAVES ( Ye, 2007 ) is also conducted for the same optimum pattern for comparison purposes. The effectiveness of the partial Ground Improvement Method has been proved by both the shaking table test and the numerical analysis.
Anne Raich - One of the best experts on this subject based on the ideXlab platform.
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Behavior and Soil–Structure Interaction of Pervious Concrete Ground-Improvement Piles under Lateral Loading
Journal of Geotechnical and Geoenvironmental Engineering, 2016Co-Authors: Muhannad T Suleiman, Anne RaichAbstract:AbstractGranular column Ground-Improvement Methods are widely used to improve bearing capacity and provide a drainage path. However, the behavior of granular columns depends on the confinement provided by the surrounding soil, which limits their use in poor soils. A new Ground-Improvement Method is proposed using pervious concrete piles to provide high permeability while also providing higher stiffness and strength, which are independent of surrounding soil confinement. Building on prior research on the behavior of vertically loaded pervious concrete piles and granular columns, this paper investigates the behavior of laterally-loaded pervious concrete piles and the effects of installation on their response. Two fully-instrumented lateral load tests were conducted on a precast and cast-in-place pile using different installation Methods. Advanced sensors measured the soil–structure interaction during installation and under lateral loading. Test results confirmed that laterally-loaded pervious concrete groun...
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development of pervious concrete pile Ground Improvement alternative and behavior under vertical loading
Journal of Geotechnical and Geoenvironmental Engineering, 2014Co-Authors: Muhannad T Suleiman, Lusu Ni, Anne RaichAbstract:Permeable granular columns are used to increase the time rate of consolidation, reduce liquefaction potential, improve bearing capacity, and reduce settlement. However, their behavior depends on the confinement provided by surrounding soil, which limits their use in very soft clays and silts, and organic and peat soils. This research effort aims to develop a new Ground-Improvement Method using pervious concrete piles. Pervious concrete piles provide higher stiffness and strength that are independent of surrounding soil confinement while offering permeability comparable to granular columns. This proposed Ground-Improvement Method can improve the performance of different structures supported on poor soils. To achieve the goal of the research project, four vertical load tests were performed on one granular column and three pervious concrete piles. In this paper, the material properties of pervious concrete, the developed installation Method, and the vertical load response of pervious concrete and aggregate piles are presented, and the variation of soil stresses and displacement during pile installation are briefly discussed. The experimental test results show that the ultimate load capacity of the pervious concrete pile was 4.4 times greater than that of an identical granular column. In addition, the ultimate load capacity of a pervious concrete pile installed using the developed technique was 2.6 times greater than a precast pervious concrete pile. The used installation Method created nonuniform lateral soil displacement and increased vertical and horizontal soil stresses.
