• Title/Summary/Keyword: Undrained shear strength

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A Study on Characteristics of Undrained Shear Strength of Remolded Marine Clays at Incheon (인천 재성형 해성점토의 비배수 전단강도 특성에 대한 연구)

  • Yoo, Nam-Jae;Lee, Han-Sol;Jun, Sang-Hyun
    • Journal of Industrial Technology
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    • v.29 no.B
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    • pp.81-88
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    • 2009
  • The main purpose of this work is to determine characteristics of undrained shear strength of remolded marine clay at Incheon. Laboratory vane tests with remolded marine clay sampled from west coast at Incheon were performed to investigate the undrained shear strength of them being dumped for reclamation after dredging from the sea bottom. Test results were compared with the predicted values of undrained shear strength proposed by many researchers. It was found that measured results about undrained shear strength with water content was in good agreements with values proposed by Mikasa and Modified Mikasa's empirical formula.

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A Study on Characteristics of Undrained Shear Strength of Remolded Marine Clays at Incheon and Busan (인천 및 부산 재성형 해성점토의 비배수 전단강도 특성에 대한 연구)

  • Yoo, Nam-Jae;Lee, Han-Sol;Jun, Sang-Hyun
    • Journal of Industrial Technology
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    • v.30 no.A
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    • pp.103-109
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    • 2010
  • This research is to determine characteristics of undrained shear strength of remolded marine clay at Incheon and Busan, representing typical marine clays in Korea. Laboratory vane tests with remolded marine clays sampled from coasts at Incheon and Busan were performed to investigate the undrained shear strength of them. Test results were compared with the predicted values of undrained shear strength proposed by many researchers. It was found that measured results about undrained shear strength with water content was in good agreements with values proposed by Terzaghi empirical formula.

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Effects of Anisotropic Consolidation on Strength of Soils (이방압밀이 흙의 강도에 미치는 영향)

  • 강병희
    • Proceedings of the Korean Geotechical Society Conference
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    • 2000.11a
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    • pp.3-14
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    • 2000
  • Anisotropic consolidation, shear, a transportational component during or after deposition each may produce anisotropic fabrics, which result in the anisotropic properties of soils. Nevertheless, the isotropically consolidated compression triaxial tests are commonly used in practice to determine the strength of the anisotropically consolidated soils because of their practicality and simplicity. In this paper the effects of anisotropic consolidation on the strength properties of soils are discussed. For the sandy soils consolidated under a constant vertical consolidation pressure, the deformation modulus decreases with decreasing consolidation pressure ratio($\sigma$$\sub$3c/'/$\sigma$ sub 1c/'), but the liquefaction resistance increases. For the saturated cohesive soils, both the undrained shear strength and undrained creep strength decrese with decreasing the consolidation pressure ratio. When the in-situ strength properties of the anisotropically and normally consolidated soils are determined by the isotropically consolidated tests, the undrained shear strength and creep strength of saturated cohesive soils as well as the deformation modulus of sandy soils are measured to be higher than the rear in-situ values. This, therefore, could lead to a dangerous judgement in stability analysis

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Influence of coarse particles on the physical properties and quick undrained shear strength of fine-grained soils

  • Park, Tae-Woong;Kim, Hyeong-Joo;Tanvir, Mohammad Taimur;Lee, Jang-Baek;Moon, Sung-Gil
    • Geomechanics and Engineering
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    • v.14 no.1
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    • pp.99-105
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    • 2018
  • Soils are generally classified as fine-grained or coarse-grained depending on the percentage content of the primary constituents. In reality, soils are actually made up of mixed and composite constituents. Soils primarily classified as fine-grained, still consists of a range of coarse particles as secondary constituents in between 0% to 50%. A laboratory scale model test was conducted to investigate the influence of coarse particles on the physical (e.g., density, water content, and void ratio) and mechanical (e.g., quick undrained shear strength) properties of primarily classified fine-grained cohesive soils. Pure kaolinite clay and sand-mixed kaolinite soil (e.g., sand content: 10%, 20%, and 30%) having various water contents (60%, 65%, and 70%) were preconsolidated at different stress levels (0, 13, 17.5, 22 kPa). The quick undrained shear strength properties were determined using the conventional Static Cone Penetration Test (SCPT) method and the new Fall Cone Test (FCT) method. The corresponding void ratios and densities with respect to the quick undrained shear strength were also observed. Correlations of the physical properties and quick undrained shear strengths derived from the SCPT and FCT were also established. Comparison of results showed a significant relationship between the two methods. From the results of FCT and SCPT, there is a decreasing trend of quick undrained shear strength, strength increase ratio ($S_u/P_o$), and void ratio (e) as the sand content is increased. The quick undrained shear strength generally decreases with increased water content. For the same water content, increasing the sand content resulted to a decrease in quick undrained shear strength due to reduced adhesion, and also, resulted to an increase in density. Similarly, it is observed that the change in density is distinctively noticeable at sand content greater than 20%. However, for sand content lower than 10%, there is minimal change in density with respect to water content. In general, the results showed a decrease in quick undrained shear strength for soils with higher amounts of sand content. Therefore, as the soil adhesion is reduced, the cone penetration resistances of the FCT and SCPT reflects internal friction and density of sand in the total shear strength.

Relationship Between Stiffness And Shear Strength of Normally Consolidated Clays (정규압밀점토의 강성도와 전단강도의 상관관계)

  • Park, Chi-Won;Park, Dong-Sun;Mok, Young-Jin
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.03a
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    • pp.402-413
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    • 2006
  • Strength evaluation of soft soils is a formidable task because of difficulties in sampling, specimen preparation and setting in triaxial cells. In undrained triaxial testing, sampling disturbance, verticality of specimen and bedding effect give a great influence on shear strength measurements. In the other hand, shear wave measurements of specimens are less influenced by these factors. In this research, the bender elements were attached top cap and base pedestal of triaxial cell and shear wave velocities were measured. To initiate a methodology to evaluate shear strength indirectly by measuring shear wave velocity, a relationship between shear strength and shear wave velocity was developed with kaolinite specimens consolidated in the laboratory. Undrained shear strength turns out to increase linearly with shear wave velocity. Stress-strain curves can also be predicted with a hyperbolic model and shear wave measurements.

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Relationship between Shear Wave Velocity, Undrained Shear Strength and Density of Normally Consolidated Silt (실트질 세립토의 전단파속도와 비배수 전단강도 및 밀도의 상관관계)

  • Park, Dong-Sun;Oh, Sang-Hoon;Mok, Young-Jin
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.03a
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    • pp.318-326
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    • 2008
  • Recently, a new seismic probe, called "MudFork", has been developed and can be utilized for accurate and easy measurements of shear wave velocities of soft soils. To expand its use to estimate undrained shear strength and density, correlations between those and shear wave velocity were being attempted. Cone penetration tests and a seismic test, using MudFork, were performed at a soft ground site near Incheon, Korea. Also, undisturbed samples were obtained and shear wave velocities of the samples were measured as well as undrained shear strength, using triaxial compression test and bender elements. A simple linear relationship between shear strength and shear wave velocity was obtained, and a tentative relationship between density and shear wave velocity was also defined.

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Characteristics of Behavior of Pressurized light-weight steel Anchor according to undrained shear strength (비배수 전단강도에 따른 압입식 경량강재앵커블록의 거동 특성)

  • Heo, Yol;Ahn, Kwang-Kuk;Park, Kyoung-Soo;Lee, Yong-Jun;Kang, Hong-Sig
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.09a
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    • pp.219-224
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    • 2009
  • In this study, the characteristics of pullout behavior of Pressurized light-weight steel Anchor was investigated through centrifuge model tests considering pull-out angle $0^{\circ}$ with changing undrained shearstrength(0~1, 2~4, 5~7kPa) of clay. According to the results of tests, the yield pullout load of clay ground was gradually increased up to 30% as undrained shear strength was increased. Therefore, it was known that the yield pullout load was affected by increasing the undrained shear strength, in addition, the pattern of behavior was not changed.

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Shear Rate Effect on Undrained Shear Behavior of Holocene Clay (자연 퇴적 점성토의 비배수 전단강도에 미치는 전단 속도의 영향)

  • Jung, Min-Su;Chae, Jong-Gil;Shibuya, Satoru
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.10a
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    • pp.1181-1192
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    • 2008
  • A laboratory investigation was carried out into effects of strain rate on undrained shear behavior of Holocene clay underneath Kobe Airport with an objective to evaluate the factor of safety of the retaining structure built on it. It was examined in a series of triaxial compression and extension tests performed using different rate of axial straining. A comparative compression test in which the strain rate was changed in steps was also carried out. Similar tests were performed in constant-volume direct shear box (DSB) test. And, the deformation characteristics of the clay were also examined in order to evaluate the variation of stiffness during undrained shearing. It was found that the undrained strength increased with not only the shear rate but also the consolidation period. ISOTACH properties seemed a key to govern the undrained shear behavior.

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Feasibility of Artificial Neural Network Model Application for Evaluation of Undrained Shear Strength from Piezocone Measurements (피에조콘을 이용한 점토의 비배수전단강도 추정에의 인공신경망 이론 적용)

  • 김영상
    • Journal of the Korean Geotechnical Society
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    • v.19 no.4
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    • pp.287-298
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    • 2003
  • The feasibility of using neural networks to model the complex relationship between piezocone measurements and the undrained shear strength of clays has been investigated. A three layered back propagation neural network model was developed based on actual undrained shear strengths, which were obtained from the isotrpoically and anisotrpoically consolidated triaxial compression test(CIUC and CAUC), and piezocone measurements compiled from various locations around the world. It was validated by comparing model predictions with measured values about new piezocone data, which were not previously employed during development of model. Performance of the neural network model was compared with conventional empirical method, direct correlation method, and theoretical method. It was found that the neural network model is not only capable of inferring a complex relationship between piezocone measurements and the undrained shear strength of clays but also gives a more precise and reliable undrained shear strength than theoretical and empirical approaches. Furthermore, neural network model has a possibility to be a generalized relationship between piezocone measurements and undrained shear strength over the various places and countries, while the present empirical correlations present the site specific relationship.

Assessment on Design Applicability of Analysis of the Undrained Shear Strength in Korea Coastal Marine Clay (국내 해성점토의 비배수 전단강도 분석을 통한 설계 적용성 평가)

  • Kim, Myeong Hwan;Song, Chang Seob
    • Journal of The Korean Society of Agricultural Engineers
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    • v.58 no.1
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    • pp.61-71
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    • 2016
  • This study performed the physical and mechanical experiment on the samples of costal marine clays individually collected in western and southern regions to identify the characteristics of western and southern costal marine clay. Based on the experiment result, the characteristics of costal marine clay is identified undrained shear strength. Based on the experiment result on the physical and mechanical characteristics of costal marine clays, the regression is presented that can analyze the mechanical characteristics of undrained shear strength in costal marine clay of Korea, region of Korea and western-southern region. The correlation of uniaxial compressive strength and undrained shear strength was suitable for use of western-southern region correlation equation. The test result of Jeonnam Yeosu area compares with prediction results of previous researchers formula and western-southern region formula. Prediction results appear highest reliability on the 0.827 of coefficient of determination in the prediction results of the western-southern region formula.