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拘束圧に対する強度非線形性を考慮した、複合荷重を受ける層状地盤上の基礎の支持力評価
No full textDue to the complexity of the interaction mechanism between soil and foundation, foundation design, is still considered as one of the most difficult tasks in geotechnical engineering. There are many types of foundation, and the bearing capacity of each foundation type is governed both by its structural strength, the supporting soil properties and the forces acting on it. In this thesis, the bearing capacities of three types of foundations are being investigated using: An in-house FEM code, namely, the rigid-plastic finite element method; Physical modeling and 3D elastic-Plastic FEM. (1) the bearing capacity of strip footing on two-layered c-φ soils, (2) the end bearing capacity of Incompletely End Supported Pile (IESP), (3) the bearing capacity characteristics of spiral pile subjected to combined loads. In the case of strip footing, the bearing capacity was investigated by considering layer factors. The influences of the following ratios on the bearing capacity factors were investigated: The ratio of the tangent of the angle of friction of the bottom layer to that of the top layer; the ratio of the cohesion of the bottom layer to that of the top layer; the ratio of the unit weight of the bottom layer to that of the top layer, and the ratios of the embedment of the footing and the thickness of the top layer to the footing width. Based on the influences of those ratios, layer factors are determined. Several types of failure mechanics were found and the conditions of occurrence of each failure type are summarized in a chart. A new approach for stimating the bearing capacity of strip footings on two-layered c-φ soils is proposed. A comparison with available methods in the literature has confirmed the reliability of the proposed method, showing the application limitation of the past research. In the case of IESP, the end bearing capacity was investigated considering shear strength nonlinearity of soil against confining pressure, and soil-foundation interaction. The effect of the distance between the pile tip and the bottom hard soil layer (d/B) on the end-bearing capacity of IESP was mainly investigated. The influence of ratio (r) of the end bearing capacity of the pile when it reaches the bottom hard layer to the end bearing capacity of the pile when the bottom layer has no influence was also investigated. As a result, the consideration of the shear strength non-linearity leads to accurate estimation of the end bearing capacity, affects the failure patterns and matches previous analytical, experimental and numerical solutions. It is found that the end bearing capacity inversely decreases with the distance d/B and becomes constant around d/B = 3. Based on the results, a formula for estimating the end bearing capacity of IESP is proposed. And comparisons with methods in existing literature have confirmed the reliability of the proposed equation. In the case of the spiral pile, a series of push-in, pull-out and horizontal loading tests on spiral piles constructed on soft and viscous ground was conducted, and a method to easily consider the integration effect of surrounding ground by rotational press-fitting is proposed. Subsequently, based on the proposed method, a small-diameter spiral pile is modelled with FEM analysis, various test results were reproduced and parameters to consider the integration effect of the surrounding ground, in numerical analysis, are identified. By the same FEM analysis method, using the identified parameters, the bearing capacity characteristics of the vertical and batter spiral pile for the combined load are obtained. Finally, based on the results, formulas for the bearing capacity envelopes in H-V-M space are proposed and the accuracies of the formulas are verified
Bearing capacity evaluation of various types of foundations subjected to combined load in layered grounds considering nonlinearity of strength against confining pressure
No full textBearing capacity evaluation of small-diameter spiral piles in soft ground subjected to combined loads
Get PDFIn the current practices, the evaluation method for the bearing capacity of small-diameter spiral piles is a conservative method performed on the safe side, since it does not consider the integration effect with the surrounding ground due to rotational press-fitting. In addition, the evaluation method for the bearing capacity of spiral piles subjected to combined loads has not been established. In this study, a series of push-in, pull-out, and horizontal loading tests on spiral piles constructed on a soft viscous ground is conducted, and a method to easily consider the integration effect of the surrounding ground by rotational press-fitting is proposed. Subsequently, based on the proposed method, small-diameter spiral piles are modelled with a FEM analysis, various test results are reproduced, and coefficients for considering the integration effect of the surrounding ground in a numerical analysis are established. With the same FEM analysis method, using the established coefficients, the bearing capacity characteristics of vertical and batter spiral piles for combined loads are obtained. Finally, based on the results, formulas for the bearing capacity envelopes in the H-V-M space are proposed and the accuracy of the formulas are verified
End bearing capacity of a single incompletely end-supported pile based on the rigid plastic finite element method with non-linear strength property against confining stress
No full textBearing capacity evaluation of small-diameter spiral piles in soft ground subjected to combined loads
No full textEnd bearing capacity of a single incompletely end-supported pile based on the rigid plastic finite element method with non-linear strength property against confining stress
Get PDFAn Incompletely End Supported Pile (IESP) is a pile in a soft soil layer underlain by a hard soil layer that does not reach the bottom hard layer in practice. This study estimates the end bearing capacity of IESP by using an inhouse Rigid Plastic FEM code (RPFEM), considering shear strength non-linearity of soil against confining pressure, and soil-foundation interaction. The effect of the distance between the pile tip and the bottom hard soil layer (d/B) on the end-bearing capacity of IESP was mainly investigated for three types of soil: cohesive soils, cohesionless soils and intermediate soils. Also, theratio (r) of the end bearing capacity of the pile when it reaches the bottom hard layer to that of the pile when the bottom layer has no influence was was considered. By considering the shear strength non-linearity, the end bearing capacity was accurately estimated. The estimations were consistent with previous analytical, experimental and numerical solutions. It is found that the end bearing capacity inversely decreases with the distance d/B and becomes constant around d/B = 3. Based on the results, a formula for estimating the end bearing capacity of IESP is proposed. Comparisons with methods in existing literature confirmed the reliability of the proposed equation
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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