• Title/Summary/Keyword: consolidation history

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Consolidation of democracy and historical legacies: a case study of Taiwan

  • Schafferer, Christian
    • Journal of Contemporary Eastern Asia
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    • v.9 no.1
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    • pp.23-41
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    • 2010
  • In political science there is broad interest in whether a newly established democracy succeeds in overcoming the perils of democratisation and matures into a consolidated democracy or regresses to authoritarianism. Taiwan was under martial law for almost four decades. Democratic consolidation, therefore, is primarily a question of how to overcome the legacies of the former authoritarian regime. Nationalism and dysfunctional political institutions are some of the legacies that limit Taiwan's democratic development. The study of these destructive elements is important in the attempt to interpret Taiwan's most recent political history and to formulate effective democracy-building policies. In the following, I would like to address the aforementioned legacies and their implications for Taiwan's current and future democratic development.

Excessive Settlement Back-Analysis of Railway Embankment on Soft Soils during Service

  • Ahn, Taebong
    • Journal of the Korean GEO-environmental Society
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    • v.20 no.1
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    • pp.13-17
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    • 2019
  • This paper presents case history of railway embankment excess settlement on soft clay during service in southern region of Korea. A lot of field observations show that the measured settlements are a lot larger than settlements actually calculated in this area. Back analysis is carried out to verify the soil parameters which are intended to investigate in the subsurface exploration phase and later in a laboratory test program. Recommendations and causes for the engineering practice are suggested to review the determination of excess settlements and, consequently, to improve the settlement prediction. This enormous discrepancy is due to the passing over secondary consolidation, and the design filling did not meet to real construction filling. Immediate settlement could be subsidiary factor of excess settlement.

Characteristics of Shear Strength and Consolidation Behavior of Soft Ground according to Stage Fill (단계성토에 따른 연약지반의 전단강도 및 압밀거동 특성)

  • Bang, Seongtaek
    • Journal of the Korean GEO-environmental Society
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    • v.21 no.7
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    • pp.17-26
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    • 2020
  • The soft ground in the southwest coastal area composed of marine clay is greatly influenced by sediment composition, particle size distribution, particle shape, adsorption ions and pore water characteristics, tide and temperature. In addition, the geotechnical properties are very complex due to stress history, change in pore water, dissolution process and gas formation. In this study, the physical and mechanical properties of the soft ground were evaluated through field tests and laboratory tests to investigate the strength increase characteristics according to consolidation on the soft ground in the southwest coast. In addition, in order to understand the consolidation behavior of soft ground such as subsidence, pore water pressure, horizontal displacement of soil by embankment load, measuring instruments such as pore water pressuremeter, settlement gauge, inclinometer and differential settlement gauge was installed, and a piezocon penetration test was carried out step by step to confirm the increase in shear strength of the ground. Through this, it was confirmed that the shear strength of the ground is increased according to the stages of filling. In addition, by evaluating the properties of consolidation behavior, strength increase and consolidation prediction by empirical methods and theories were compared to analyze the characteristics of strength increase rate and consolidation behavior in consideration of regional characteristics.

Compressibility Characteristics of Pusan Clays (부산점토의 압축특성)

  • ;;Pham Huy Giao
    • Proceedings of the Korean Geotechical Society Conference
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    • 2000.11a
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    • pp.361-368
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    • 2000
  • In other to examine the compressibility characteristics of cohesive soils in the mouth of the Nakdong river, the oedometer tests were peformed on undisturbed and reconstituted samples obtained by continuous boring typically at 3 different sites. It is meaningful to compare the consolidation behavior of natural clays with a reference state because the natural clays are depending on the stress history, sedimentary environment and geological history. In this study, the insitu state of the Pusan clays was investigated using the concepts of ISL(Nagaraj, 2000) and ICL and SCL(Burland, 1990). And for the purpose of confirming the existence of the underconsolidated clays, a standpipe type piezometer test and a dissipation test by piezocone were performed at their sites. Consequently, the Pusan clays were evaluated as normally consolidated clays.

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Development of Geometry in the 19th century and Birth of Lie's theory of Groups (19세기 기하학의 발달과 리군론의 시작)

  • Kim, Young Wook;Lee, Jin Ho
    • Journal for History of Mathematics
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    • v.29 no.3
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    • pp.157-172
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    • 2016
  • Sophus Lie's research is regarded as one of the most important mathematical advancements in the $19^{th}$ century. His pioneering research in the field of differential equations resulted in an invaluable consolidation of calculus and group theory. Lie's group theory has been investigated and constantly modified by various mathematicians which resulted in a beautifully abstract yet concrete theory. However Lie's early intentions and ideas are lost in the mists of modern transfiguration. In this paper we explore Lie's early academic years and his object of studies which clarify the ground breaking ideas behind his theory.

Prediction of Stress-strain Behavior for Anisotropic Consolidated Compacted Decomposed Granite Soil (비등방 압밀된 다짐화강풍화토의 응력-변형률 거동 예측)

  • 정진섭;양재혁
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.45 no.2
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    • pp.86-95
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    • 2003
  • During this study, constant stress ratio tests with previous compression anisotropic stress history are performed on compacted decomposed granite soil sampled at Iksan, Jeonbuk. Yielding points are determined from stress-strain curves. The shape and characteristics of compression anisotropic yield curves is examined. In addition, the measured value of yielding curve and stress-strain behavior is predicted by Yasufuku's anisotropic constitutive model based on non-associated flow rule. The main results are summarized as follows : 1) Shape of yielding curves shows almost ellipse but asymmetry with respect to stress path during previous consolidation stress. 2) Yasufuku's anisotropic constitutive model is suitable in evaluation of yielding curves on anisotropic consolidated decomposed granite soil. 3) The predicted stress-strain curve shows reasonable agreement to measured behaviours.

A Study on the Measuring about the Coefficient of Earth Pressure at Rest 1 (정지토압계수 측정에 관한 연구 1)

  • 송무효
    • Journal of Ocean Engineering and Technology
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    • v.15 no.4
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    • pp.92-100
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    • 2001
  • It is very important to determine the coefficient of earth pressure at rest accurately in order to estimate the behavior of soil structure. For estimation of K/sub 0/-value depending upon the stress history of dry sand, a new type of K/sub 0/-oedeometer apparatus is devised, and the horizontal earth pressure is accurately measured. For this study, 2 types of one-cyclic K/sub 0/-Loading/unloading models have been studied experimentally using four relative densities of the sand. The results obtained in this test are as follows : K/sub on'/ the coefficient of earth pressure at - rest for virgin loading is a function of the angle of internal friction Φ' of the sand and is determined as K/sub on/=1 - 0.914 sin Φ', K/sub ou'/ the coefficient of earth pressure at rest for virgin unloading is a function of K/sub on/ and over consolidation ratio(OCR), and is determined as K/sub ou/=K/sub on/(OCR)K/sup a/. The exponent α, increases as the relative density increases. K/sub or'/ the coefficient of earth pressure at rest for virgin reloading decreases in hyperbola type as the vertical stress, σ/sub v/’, increases. And, the stress path at virgin reloading leads to the maximum prestress point, independent upon the value of the minimum unloading stress. The gradient of this curve, m/sub r/ increases as OCR increases.

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PRACTICAL MODELLING OF STONE-COLUMN REINFORCED GROUND

  • Tan By S.A.;Tjahyono S.
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.10a
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    • pp.291-311
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    • 2006
  • The acceleration of consolidation by stone columns was mostly analysed within the framework of a basic unit cell model (i.e. a cylindrical soil body around a column). A method of converting the axisymmetric unit cell into the equivalent plane-strain model would be required for two-dimensional numerical modelling of multi-column field applications. This paper proposes two practical simplified conversion methods to obtain the equivalent plane-strain model of the unit cell, and investigates their applicability to multi-column reinforced ground. In the first conversion method, the soil permeability is matched according to an analytical equation, whereas in the second method, the column width is matched based on the equivalence of column area. The validity of these methods is tested by comparison with the numerical results of unit-cell simulations and with the field data from an embankment case history. The results show that for the case of linear-elastic material modelling, both methods produce reasonably accurate long-term consolidation settlements, whereas for the case of elasto-plastic material modelling, the second method is preferable as the first one gives erroneously lower long-term settlements, where plastic yielding of stone column are ignored.

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Geotechnical Characteristics of Soft Clay in Myungji Housing Complex (부산 명지주거단지 연약 점토의 지반 공학적 특성)

  • Lee, Suk-Jin;Yang, Hee-Jeong;Lee, Jun-Ho;Kim, Jung-Kwan;Sung, Sang-Gyu;Lee, Joo-Ho
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.03a
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    • pp.445-454
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    • 2006
  • Myungji Housing Complex is located in the Nakdong River plain in which the Busan soft clays are developed. It has thick soft soil laver of about GL(-)50m including loose sandy layers, upper and lower clayey layers. The clayey layers have been being consolidated since the land reclamation was completed to build the place for Housing Complex(Apartment) in 1997. Therefore, as one of a series of advance preparations of this project, study was carried on the geotechnical characteristics under the foundation The first part of this paper represents a brief geological history. Then, geotechnical characteristics of clay was analyzed in the classical developments in soft clay. They were based on the geotechnical data obtained by site investigations performed from 1992 to 2005. Finally, we evaluated the average degree of consolidation at this point in time and the residual settlements of upper clayey layer using dissipation and oedometer tests for this project

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Development of Dissipation Model of Excess Pore Pressure in Liquefied Sand Ground (액상화된 모래지반의 과잉간극수압 소산모델 개발)

  • Kim, Sung-Ryul;Hwang, Jae-Ik;Ko, Hon-Yim;Kim, Myoung-Mo
    • Journal of the Korean Geotechnical Society
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    • v.23 no.10
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    • pp.13-22
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    • 2007
  • Recently, many researches on the dissipation of excess pore pressure in liquefied sand grounds have been performed to evaluate post-liquefaction behavior of structures. In this research, centrifuge tests were performed to analyze liquefaction behavior of level saturated sand grounds. Based on the test results, the evaluation model of solidified layer thickness was developed to simulate non-linear variation of the thickness with time. The thickness evaluation model was combined with the solidification theory and the consolidation theory in order to simulate dissipation of excess pore pressure. The suggested dissipation model properly estimated the solidified layer thickness and the time history of excess pore pressure.