The Experts below are selected from a list of 471 Experts worldwide ranked by ideXlab platform
Yishou Chen - One of the best experts on this subject based on the ideXlab platform.
-
Lateral Bearing Capacity and failure mode of geosynthetic reinforced soil barriers subject to Lateral loadings
Geotextiles and Geomembranes, 2016Co-Authors: Kuohsin Yang, Jonathan T H Wu, Rongher Chen, Yishou ChenAbstract:Abstract In addition to self-weight and vertical surcharge, geosynthetic-reinforced soil (GRS) structures have recently been used as barriers to resist Lateral forces from natural disasters, such as floods, tsunamis, rockfalls, debris flows, and avalanches. The stability of such structures subject to Lateral loading is often evaluated using conventional external stability analyses with the assumption that the reinforced soil mass is a rigid body. However, this assumption contradicts the flexible nature of reinforced soil. In this study, finite element (FE) models of back-to-back GRS walls were developed to investigate the performance of GRS barriers subject to Lateral loading. The FE analysis results indicated that the failure mode and Lateral Bearing Capacity of GRS barriers depend largely on the aspect ratio ( L/H : ratio of wall width to wall height). When 0.5 L/H L/H L/H > 3.0, passive soil failure would occur within the GRS barriers at the side subject to the Lateral force. The ultimate Lateral Bearing Capacity of GRS barriers increased with an increase in L/H : the ultimate Lateral Capacity factor N L was 1.4–20.1 times K a for L/H = 0.5–3.0. In addition to the effect of L/H , the numerical results indicated that the backfill friction angle ϕ , unit weight γ , and reinforcement vertical spacing S v considerably affected the Lateral Bearing Capacity of GRS barriers. A hypothetical case study of a GRS barrier against a tsunami force is provided, and a viable method using vertical preloaded soil anchors for improving wall Lateral Capacity is analyzed and discussed.
-
numerical study on Lateral Bearing Capacity and failure mode of geosynthetic reinforced soil barriers
Japanese Geotechnical Society Special Publication, 2016Co-Authors: Kuohsin Yang, Jonathan T H Wu, Rongher Chen, Yishou ChenAbstract:In addition to vertical surcharges, geosynthetic-reinforced soil (GRS) structures have recently been used as barriers to resist Lateral forces from natural disasters such as floods, tsunamis, rock falls, debris flows, and avalanches. The stability of such structures is often evaluated by conducting conventional external stability analyses with an assumption that the reinforced soil mass is a rigid body. However, this assumption contradicts the flexible nature of reinforced soil. In this study, finite element (FE) models of back-to-back GRS walls were developed to investigate the behavior of GRS barriers subjected to Lateral loadings. The FE results indicate that GRS barriers subjected to Lateral loadings fail internally. The failure model and the Lateral Bearing Capacity depend on the aspect ratio (L/H: ratio of wall width to wall height) of GRS barriers. When 0.5 3.0, passive soil failure occurs within GRS barriers at the side subjected to the Lateral force. As L/H increases, the Lateral Bearing Capacity of GRS barriers increases to approximately three times the active Lateral earth pressure at L/H = 0.7 to the passive Lateral earth pressure at L/H = 3.0. In addition to the effect of L/H, the internal soil failure predicted by FE analyses suggests that the soil shear strength plays a major role in determining the Lateral Bearing Capacity of GRS barriers. A hypothetical case study of a GRS barrier against a tsunami force is provided and an improved method is discussed.
Konstantinos Georgiadis - One of the best experts on this subject based on the ideXlab platform.
-
Undrained limiting Lateral soil pressure on a row of piles
Computers and Geotechnics, 2013Co-Authors: Konstantinos Georgiadis, Scott W. Sloan, Andrei V. LyaminAbstract:Abstract The displacement finite element, lower and upper bound finite element limit analysis and analytical upper bound plasticity methods are employed to investigate the undrained limiting Lateral resistance of piles in a pile row. Numerical analyses and analytical calculations are presented for various pile spacings and pile–soil adhesion factors. The numerical results are shown to be in excellent agreement with each other and also with the theoretical upper bounds produced by the analytical upper bound calculations. Based on the numerical and analytical results, an empirical equation is proposed for the calculation of the ultimate undrained Lateral Bearing Capacity factor. This equation is subsequently used to calculate p-multipliers applicable to the lower part of piles in pile rows, which are compared to multipliers available in the literature (that are constant with depth). The comparison shows significant differences, indicating that the amount of reduction in Lateral resistance due to group effects is not constant with depth as routinely assumed in practice.
-
Ultimate Lateral pressure of two side-by-side piles in clay
Geotechnique, 2013Co-Authors: Konstantinos Georgiadis, Scott W. Sloan, Andrei V. LyaminAbstract:The ultimate earth resistance for a group of two side-by-side piles that are Laterally loaded in clay is investigated using four different methods of analysis: three numerical (the displacement finite-element method, and the upper- and lower-bound finite-element limit analysis methods) and one analytical (an analytical upper-bound plasticity method developed in this paper). The results of the three numerical methods are shown to be in excellent agreement, while the analytical solution presents a theoretical upper bound that is very close to the numerical results. The results of the analyses are used to identify the predominant failure mechanisms for different pile spacings and pile–soil adhesions. They are also used to develop a design chart and design equations for determination of the ultimate Lateral Bearing Capacity factor.
-
Lateral Bearing Capacity of rigid piles near clay slopes
Soils and Foundations, 2013Co-Authors: Konstantinos Georgiadis, Michael C Georgiadis, C AnagnostopoulosAbstract:Abstract Analytical equations were derived to determine the undrained Lateral Bearing Capacity of rigid piles in cohesive soil. Piles in level ground and piles placed at a distance from the crest of a slope were examined, taking account of the effect of the adhesion at the pile–soil interface. The derived analytical solutions were used to develop charts relating the Lateral pile Capacity to the pile length/diameter ratio, the pile–soil adhesion, the distance of the point of load application from the ground to the pile diameter ratio, the inclination of the slope and the distance of the pile from the crest of the slope to the pile diameter ratio. They were also used to derive a reduction factor which, when multiplied by the Lateral Bearing Capacity for level ground, gives the Bearing Capacity of the same pile near a slope. In addition, a critical non-dimensional distance between the pile and the crest of the slope, at which the Bearing Capacity approaches that for a level ground, was determined. The Bearing Capacity charts obtained for level ground were compared to the classic Broms' charts and to others derived using several different Lateral earth pressure distributions along the pile. Comparisons were also made between the results of the proposed method for piles near slopes and those obtained from charts based on upper bound calculations. Finally, the proposed new method was validated through a comparison with the results of a large number of pile load tests, in which a remarkable agreement was observed between the analytical results and the measurements.
Wei Shao - One of the best experts on this subject based on the ideXlab platform.
-
Degradation of Lateral Bearing Capacity of piles in soft clay subjected to cyclic Lateral loading
Marine Georesources & Geotechnology, 2019Co-Authors: Wei Shao, Dongyan YangAbstract:AbstractIn this article, the degradation of the Lateral Bearing Capacity of piles in soft clay subjected to cyclic Lateral loading is studied numerically. A modified kinematic hardening constitutive model is employed to simulate the degradation of soft clay after cyclic loading. The modified model is verified by comparing the numerical simulation results with the results of centrifuge model tests. Furthermore, the modified model is applied to numerical simulations for evaluating the Lateral Bearing Capacity of piles in soft clay subjected to cyclic Lateral loading. The degradation of the Lateral Bearing Capacity of piles in soft clay after different cyclic displacement levels and different numbers of cycles is investigated. The study reveals that the modified kinematic hardening constitutive model can effectively estimate the cyclic degradation behavior of piles in soft clay subjected to cyclic Lateral loading. The degradation of the ultimate Lateral Bearing Capacity progresses slowly with increasing cycl...
-
degradation of Lateral Bearing Capacity of piles in soft clay subjected to cyclic Lateral loading
Marine Georesources & Geotechnology, 2019Co-Authors: Wei Shao, Dongyan YangAbstract:In this article, the degradation of the Lateral Bearing Capacity of piles in soft clay subjected to cyclic Lateral loading is studied numerically. A modified kinematic hardening constitutive model ...
Makoto Kimura - One of the best experts on this subject based on the ideXlab platform.
-
Design approach to a method for reinforcing existing caisson foundations using steel pipe sheet piles
Soils and Foundations, 2014Co-Authors: Koichi Isobe, Makoto Kimura, Satoru OhtsukaAbstract:Abstract This paper proposes a steel pipe sheet pile (SPSP) reinforcement method for existing caisson foundations in water. The technique involves driving SPSPs around the caisson foundation and connecting them to it with reinforcing footing. To support the rational design of reinforcements using this method, the following factors influencing the technique׳s effectiveness and related mechanical behavior should be considered: (1) the conditions of the caisson/SPSP reinforcement footing connection; (2) the caisson/SPSP flexural rigidity ratio; (3) the distance between the caisson and the SPSP wall; and (4) the pile length. However, as the influence of these factors on the reinforcement effect and mechanical behavior has not yet been clarified, the current method has no standardization for the concept of the load transfer mechanism in reinforced foundation systems, and the ultimate Lateral Bearing Capacity of existing caissons has been largely ignored in previous construction. This paper describes centrifuge model tests and three-dimensional elasto-plastic finite element total stress analysis conducted in relation to real cases in order to identify a more effective and rational reinforcement structure. The static Lateral Bearing Capacity and seismic performance of reinforced foundations were investigated, and the following factors were considered: (1) the conditions of the caisson/SPSP reinforcement footing connection; (2) the caisson/SPSP flexural rigidity ratio; and (3) the pile length. Finally, a structural design flow is proposed based on the experimental and numerical simulation results. A chart to facilitate determination of appropriate reinforcement structures is also presented.
-
Centrifuge model test and numerical analysis on steel pipe sheet piles reinforcement method
GeoCongress 2008, 2008Co-Authors: Koichi Isobe, Makoto KimuraAbstract:Steel pipe sheet pile (SPSP) reinforcing method for existing caisson foundation in water, which involves driving SPSP around the caisson foundation and then connecting the SPSP to the caisson at the top, is proposed. The practicability of applying this method and the reinforcement mechanism of SPSP reinforced caisson foundation system is investigated by conducting three-dimensional elasto-plastic finite element analysis. In the simulation, to propose more effective and reasonable design / construction method, the following factors that affect the effectiveness of SPSP reinforcement are considered: 1) connection condition of the caisson to SPSP reinforcement; 2) pile length. Based on the results of analysis, the authors try to estimate the SPSP reinforcement effect and reveal the mechanism which the Lateral Bearing Capacity of reinforced foundation system is increasing.
-
DEVELOPMENT AND APPLICATION OF H-JOINT STEEL PIPE SHEET PILES IN CONSTRUCTION OF FOUNDATIONS FOR STRUCTURES
Soils and Foundations, 2007Co-Authors: Makoto Kimura, Koichi Isobe, Shinya Inazumi, Yuuki Mitsuda, Yoshikazu NishiyamaAbstract:ABSTRACT This paper shows development and application potential of newly developed H-joint steel pipe sheet piles (SPSPs) in SPSP structures. The authors have developed a new H-joint SPSPs technology from a simple idea in which two steel pipes are connected by H-steel section welded on them in order to improve the performance and widen application areas of SPSP technology. The H-joint SPSP is expected to remediate problems of traditional joints in SPSPs. Installation accuracy, proposed field segment joint using a fillet welded splice plate and Lateral Bearing Capacity for H-joint SPSPs were examined by field construction tests, full-scale bending tests and centrifuge model tests, respectively. Parametric studies using beam analysis were conducted to show that the cross sectional dimensions of SPSP foundations can be reduced by using H-joint SPSPs and to estimate a joint efficiency (μ) for design of H-joint SPSP foundation structures. The following observations were made from the studies: (1) H-joint SPSP can be installed with high driving accuracy due to rigidly welding 2 steel pipes and H-steel in a factory, (2) The proposed field segment joint for H-joint SPSP using a splice plate is strong and effective in bending, (3) H-joint SPSPs have high rigidity hence large Lateral Bearing Capacity making them suitable in ensuring the stability of SPSP foundation structures, (4) A joint efficiency of H-joint SPSP foundation is larger than that of SPSP foundation with traditional joints, and (5) H-joint SPSP contributes to reducing the number of piles based on the reduction of the size dimension of the SPSP foundation.
-
centrifugal model tests on Lateral Bearing Capacity of existing caisson foundation reinforced by steel pipe sheet piles
Doboku Gakkai Ronbunshuu C, 2006Co-Authors: Koichi Isobe, Makoto Kimura, Yukihito Yoshizawa, Kenji Kohno, Noriyoshi Harata, Takeshi MakinoAbstract:渡河橋梁の班設ケーソン基礎に対する耐震補強工法として，ケーソン基礎の周囲に鋼管矢板基礎を増設しケーソン基礎と結合させることで，水平耐力を構造的に増加させ耐震性の向上を図る工法が提案されている．既に数例の施工実績を有する工法ではあるが，鋼管矢板基礎増設による補強効果や鋼管矢板基礎が分担する水平支持力の割合等のメカニズムが明確でないため，統一された設計手法が未確立であるのが現状である．本研究では，鋼管矢板基礎増設により補強されたケーソン基礎の水平支持力特性に影響を与える要因として，ケーソン基礎と鋼管矢板基礎をつなぐ頂版の結合状態，ケーソン基礎と鋼管矢板基礎の剛性比，支持層の剛性を挙げ，これらの要因が補強メカニズムに与える影響を遠心模型実験により検証した．
Koichi Isobe - One of the best experts on this subject based on the ideXlab platform.
-
Design approach to a method for reinforcing existing caisson foundations using steel pipe sheet piles
Soils and Foundations, 2014Co-Authors: Koichi Isobe, Makoto Kimura, Satoru OhtsukaAbstract:Abstract This paper proposes a steel pipe sheet pile (SPSP) reinforcement method for existing caisson foundations in water. The technique involves driving SPSPs around the caisson foundation and connecting them to it with reinforcing footing. To support the rational design of reinforcements using this method, the following factors influencing the technique׳s effectiveness and related mechanical behavior should be considered: (1) the conditions of the caisson/SPSP reinforcement footing connection; (2) the caisson/SPSP flexural rigidity ratio; (3) the distance between the caisson and the SPSP wall; and (4) the pile length. However, as the influence of these factors on the reinforcement effect and mechanical behavior has not yet been clarified, the current method has no standardization for the concept of the load transfer mechanism in reinforced foundation systems, and the ultimate Lateral Bearing Capacity of existing caissons has been largely ignored in previous construction. This paper describes centrifuge model tests and three-dimensional elasto-plastic finite element total stress analysis conducted in relation to real cases in order to identify a more effective and rational reinforcement structure. The static Lateral Bearing Capacity and seismic performance of reinforced foundations were investigated, and the following factors were considered: (1) the conditions of the caisson/SPSP reinforcement footing connection; (2) the caisson/SPSP flexural rigidity ratio; and (3) the pile length. Finally, a structural design flow is proposed based on the experimental and numerical simulation results. A chart to facilitate determination of appropriate reinforcement structures is also presented.
-
Centrifuge model test and numerical analysis on steel pipe sheet piles reinforcement method
GeoCongress 2008, 2008Co-Authors: Koichi Isobe, Makoto KimuraAbstract:Steel pipe sheet pile (SPSP) reinforcing method for existing caisson foundation in water, which involves driving SPSP around the caisson foundation and then connecting the SPSP to the caisson at the top, is proposed. The practicability of applying this method and the reinforcement mechanism of SPSP reinforced caisson foundation system is investigated by conducting three-dimensional elasto-plastic finite element analysis. In the simulation, to propose more effective and reasonable design / construction method, the following factors that affect the effectiveness of SPSP reinforcement are considered: 1) connection condition of the caisson to SPSP reinforcement; 2) pile length. Based on the results of analysis, the authors try to estimate the SPSP reinforcement effect and reveal the mechanism which the Lateral Bearing Capacity of reinforced foundation system is increasing.
-
DEVELOPMENT AND APPLICATION OF H-JOINT STEEL PIPE SHEET PILES IN CONSTRUCTION OF FOUNDATIONS FOR STRUCTURES
Soils and Foundations, 2007Co-Authors: Makoto Kimura, Koichi Isobe, Shinya Inazumi, Yuuki Mitsuda, Yoshikazu NishiyamaAbstract:ABSTRACT This paper shows development and application potential of newly developed H-joint steel pipe sheet piles (SPSPs) in SPSP structures. The authors have developed a new H-joint SPSPs technology from a simple idea in which two steel pipes are connected by H-steel section welded on them in order to improve the performance and widen application areas of SPSP technology. The H-joint SPSP is expected to remediate problems of traditional joints in SPSPs. Installation accuracy, proposed field segment joint using a fillet welded splice plate and Lateral Bearing Capacity for H-joint SPSPs were examined by field construction tests, full-scale bending tests and centrifuge model tests, respectively. Parametric studies using beam analysis were conducted to show that the cross sectional dimensions of SPSP foundations can be reduced by using H-joint SPSPs and to estimate a joint efficiency (μ) for design of H-joint SPSP foundation structures. The following observations were made from the studies: (1) H-joint SPSP can be installed with high driving accuracy due to rigidly welding 2 steel pipes and H-steel in a factory, (2) The proposed field segment joint for H-joint SPSP using a splice plate is strong and effective in bending, (3) H-joint SPSPs have high rigidity hence large Lateral Bearing Capacity making them suitable in ensuring the stability of SPSP foundation structures, (4) A joint efficiency of H-joint SPSP foundation is larger than that of SPSP foundation with traditional joints, and (5) H-joint SPSP contributes to reducing the number of piles based on the reduction of the size dimension of the SPSP foundation.
-
centrifugal model tests on Lateral Bearing Capacity of existing caisson foundation reinforced by steel pipe sheet piles
Doboku Gakkai Ronbunshuu C, 2006Co-Authors: Koichi Isobe, Makoto Kimura, Yukihito Yoshizawa, Kenji Kohno, Noriyoshi Harata, Takeshi MakinoAbstract:渡河橋梁の班設ケーソン基礎に対する耐震補強工法として，ケーソン基礎の周囲に鋼管矢板基礎を増設しケーソン基礎と結合させることで，水平耐力を構造的に増加させ耐震性の向上を図る工法が提案されている．既に数例の施工実績を有する工法ではあるが，鋼管矢板基礎増設による補強効果や鋼管矢板基礎が分担する水平支持力の割合等のメカニズムが明確でないため，統一された設計手法が未確立であるのが現状である．本研究では，鋼管矢板基礎増設により補強されたケーソン基礎の水平支持力特性に影響を与える要因として，ケーソン基礎と鋼管矢板基礎をつなぐ頂版の結合状態，ケーソン基礎と鋼管矢板基礎の剛性比，支持層の剛性を挙げ，これらの要因が補強メカニズムに与える影響を遠心模型実験により検証した．
