• Title/Summary/Keyword: laboratory vane test

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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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Selection of the optimum mixture condition for stabilization of Songdo silty clay (송도 지역 해양성 점토 고화처리를 위한 최적배합 조건의 선정)

  • Kim, Jun-Young;Jang, Eui-Ryong;Chung, Choong-Ki;Lee, Yong-Jun;Jang, Soon-Ho;Choi, Jung-Yeul
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.09a
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    • pp.412-419
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    • 2009
  • Large quantity of extra soils discharged from excavation site in Songdo area can be treated by hardening agents and utilized in surface stabilized layer overlying thick reclaimed soft soil deposit. Though surface layer stabilization method using cement or lime for very soft soils has been studied in recent years, but studies on moderately soft clayey silt has not been tried. The purpose of this research is to investigate optimum mixing condition for stabilizing Songdo marine soil with low plasiticity. The optimum mixing conditions of hardening agents with Songdo soil such as kind of agents, mixing ratio, initial water content and curing time are investigated by uniaxial compression test and laboratory vane test. The results indicate that strength increases with high mixing ratio and long curing time, while decreases drastically under certain water content before mixing. Finally, optimum mixing condition considering economic efficiency and workability with test results was proposed.

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A Reliability Study on Estimating Shear Strength of Marine Soil using CPT (Cone 관입시험을 이용한 해양토질의 전단강도 산정에 대한 신뢰도 연구)

  • 이인모;이명재
    • Geotechnical Engineering
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    • v.3 no.2
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    • pp.17-28
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    • 1987
  • Reliability of the cone penetration test (CPT) for estimating shear strength of marine soils is investigated in this paper. For sands, the uncertainty about the angle of internal friction is analyzed. It includes the spatial variation of the soil and the model error in the equation used for interpretation. The most serious uncertainty encountered was the error in the interpretative models. Different methods of interpretation gave quite different values. Subjective opinion was introduced to combine all the interpretative models in a systematic manner. For clays, the undrained Shear Strength from the CPT results is usually =derived by empirical correlations between cone resistance and untrained shear strength from laboratory tests or field vane tests, expressed in terms of cone factor and function of overburden pressure. The uncertainty of the undrained shear strength is caused by data scatter of the cone factor in the correlation, model error of the cone factor, effect of anisotropy, and spatial variability of cone resistance. Among these uncertainties, the most serious one was the data scatter of the cone factor in the .correlation. Between the laboratory test and the field vane test used for correlation, the field vane test was more reliable.

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Experiment Investigation on Fluid Transportation Performance of Propellant Acquisition Vanes in Microgravity Environment

  • Zhuang, Baotang;Li, Yong;Luo, Xianwu;Pan, Halin;Ji, Jingjing
    • International Journal of Fluid Machinery and Systems
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    • v.7 no.1
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    • pp.1-6
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    • 2014
  • The propellant acquisition vane (PAV) is a key part of a vane type surface tension propellant management device (PMD), which can manage the propellant effectively. In the present paper, the fluid transportation behaviors for five PAVs with different sections were investigated by using microgravity drop tower test. Further, numerical simulation for the propellant flow in a PMD under microgravity condition was also carried out based on VOF model, and showed the similar flow pattern for PAVs to the experiment. It is noted that the section geometry of PAVs is one of the main factors affecting the fluid transportation behavior of PMD. PAVs with bottom length ratio of 5/6 and 1/2 have larger propellant transportation velocity. Based on the experiments, there were two stages during the process of propellant transportation under microgravity environment: liquid relocation and steady transportation stage. It is also recognized that there is a linear correlation between liquid transportation velocity and relative time's square root. Those results can not only provide a guideline for optimization of new vane type PMDs, but also are helpful for fluid control applications in space environment.

Characteristics of Undrained Shear Strength of Yangsan Clay (양산지역 점토의 비배수 전단강도 특성)

  • 김길수;임형덕;이우진
    • Proceedings of the Korean Geotechical Society Conference
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    • 2000.02a
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    • pp.71-78
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    • 2000
  • SHANSEP method involves the consolidation to stresses in excess of the preconsolidation pressure in order to overcome sample disturbance effect. The concept of SHANSEP is based on an approach to laboratory test which attempts to reproduce the in-situ conditions more closely than is possible in routine tests and evaluates normalized strength parameters for the soil as a function of OCR. But SHANSEP method can be applied only to fairly uniform clay deposits, and is unsuitable for a random deposit. In this study, CK/sub o/U triaxial compression test and incremental loading consolidation test were performed for the application of SHANSEP method on Yangsan clay. During the K/sub o/-consolidation, triaxial specimens were consolidated to stress equal to two times the in-situ vertical effective stress. And for overconsolidated condition, the specimens were swelled to a known vertical effective stress in order to have the desired OCR. With the results of CK/sub o/U triaxial compression test using the block samples, the relationship between c/sub u//σ/sub vc/' and OCR on Yangsan clay was established. For evaluating the undrained shear strength of Yangsan clay with depth, CK/sub o/U triaxial compression test was performed using the piston samples taken from Yangsan site. And also undrained shear strength was analyzed from the in-situ test such as Cone Penetration Test(CPT), Dilatometer Test(DMT), and Field Vane Test(FVT) and was compared with that of CK/sub o/U triaxial compression test.

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Effect of electrochemical treatment on consolidation of soft clay

  • Li, Xiaobing;Yuan, Guohui;Fu, Hongtao;Wang, Jun;Cai, Yuanqiang
    • Geomechanics and Engineering
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    • v.15 no.4
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    • pp.957-964
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    • 2018
  • In this study, a method of electrochemical consolidation is applied. This method utilizes electro-osmosis, which is an effective ground improvement technique for soft clays, and soil treatment using lime, which is the oldest traditional soil stabilizer. The mechanism of lime treatment for soil involves cation exchange, which leads to the flocculation and agglomeration. Five representative laboratory tests-an electro-osmotic test and four electrochemical tests with various proportions of lime-were performed on dredged marine clay. The objectives of this study are to investigate the effect of electrochemical treatment and to determine the optimum dose for optimal consolidation performance of dredged marine clay. The results show that a better consolidation effect was achieved in terms of current, temperature, and vane shear strength by using electrochemical treatment. The best results were observed for the electrochemical test using 4% lime content.

The Effects of Sample Disturbance on Undrained Properties of Yangsan Clay (양산점토의 비배수 특성에 대한 시료교란의 효과)

  • 김길수;임형덕;이우진
    • Proceedings of the Korean Geotechical Society Conference
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    • 2000.03b
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    • pp.639-646
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    • 2000
  • It is important to estimate the mechanical properties of clay since it is directly related to the design and the construction of geotechnical structures. Site exploration, which is composed of boring, sampling, in-situ, or laboratory tests, is preformed to estimate the mechanical properties. However, mechanical properties of clay measured from laboratory test may be different from in-situ properties due to disturbances occurred during sampling, transportation, storage, and trimming. In this study, the degree of disturbance according to sampling method was estimated with the test results of CK/sub o/U triaxial compression test on Yangsan clay. The soil samples were obtained by three types of sampling method, j.e., 76mm-tube sampler, 76mm-piston sampler, and block sampler. In order to evaluate the quality of samples, volumetric strain, undrained shear strength, secant Young's modulus, and pore pressure coefficient at peak measured from each sample were compared with one another. From the test results, it was observed that mechanical properties of the block and piston samples were more reliable than those of tube samples. But it was observed that the water content of piston was similar to that of tube samples at given depths while the water content of block samples was 14.3∼15.8% smaller than that of piston and tube samples. In addition to the evaluation of the quality of samples, relationship between c/sub u// σ/sub vc/'and OCR was established from the results of the CK/sub o/U triaxial compression tests, which were carried out using SHANSEP method. And also undrained shear strength was analyzed using the in-situ test data such as Cone Penetration Test(CPT), Dilatometer Test(DMT), and Field Vane Test(FVT) and was compared with that evaluated from CK/sub o/U triaxial compression test.

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Evaluation of Piezocone Coefficient of Soft Grounds in the Areas of Gyeonggi and Incheon (경인지역 연약지반의 피에조콘계수 평가)

  • Park, Soo-Yong;Kim, Ki-Beom;Lee, Yun-Kyu;Baek, Seung-Cheol
    • Journal of the Korean GEO-environmental Society
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    • v.13 no.5
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    • pp.41-49
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    • 2012
  • In this study, laboratory test, in-situ vane shear test and piezocone penetration test in the study area were conducted to investigate the engineering characteristics of soft soils at Cheongra District, Songdo District in Incheon City, the west coast of Gyeonggi province, and Sihwa District in Ansan city. The correlations among compression index, and in-situ vane shear test, and cone resistance were obtained. The variations of liquid limit, plasticity index, water content and compression index with respect to depth exhibit strong similarity. This means that they have strong correlations, which can be used to evaluate the local characteristics of the study area. Thus, the correlations between compression index and physical properties were analysed to investigate the engineering characteristics of soft soil in the study area. The relationships between the measured piezocone factor by empirical methods, and undrained shear strength obtained by triaxial compression test or in-situ vane shear test were compared. It shows the significant correlation and piezocone factors, $N_{kT}$are suggested for the study area.

Determination of Undrained Shear Strength In Clay from Cone Pressuremeter Test (Cone Pressuremeter를 이용한 점성토의 전단 강도 산정)

  • 이장덕
    • Journal of the Korean Geotechnical Society
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    • v.20 no.8
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    • pp.49-58
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    • 2004
  • The cone pressuremeter test (CPM) is a new in-situ test which combines a standard cone penetration test with a pressuremeter. The cone pressuremeter tests in clay are presented and analyzed. An analytical solution of CPM incorporated non-linear soil behavior with no volume change is presented, and curve fitting technique is proposed to make use of both the loading and unloading portions of the pressuremeter test. The proposed method is accomplished by putting greater emphasis on the unloading portion. Twenty CPM tests are analyzed using the proposed method, and the derived undrained shear strength of soil is compared with other tests such as field vane tests and laboratory tests. The interpreted soil parameters had resonable values when compared to other in-situ and laboratory test results. The cone pressuremeter has provided reliable measures of undrained shear strength using curve fitting method.