• Title, Summary, Keyword: 동적콘관입시험

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Correlation Analysis between DCPT Value and SPT Value (동적콘관입시험값과 표준관입시험값의 상관성 분석)

  • Lee, Bongjik;Lee, Jongkyu
    • Journal of the Korean Geoenvironmental Society
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    • v.15 no.8
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    • pp.23-30
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    • 2014
  • In-situ penetration tests have been widely used in geotechnical engineering for site investigation in support of analysis and design. Standard Penetration Test (SPT) and Dynamic Cone Penetration Test (DCPT) are typical dynamic sounding. DCPT was originally developed as an alternative for evaluating the properties of subgrade soils. The main advantages of DCPT are that it is fast, inexpensive, and it is particularly useful in delineating areas of weak soils overlying stronger strata and in quickly assessing the variability of the soil conditions. But lack of standardization is main reason that this test method has not been advanced more in recent years. In this study, it is clarified the correlation with the SPT blow count, N from DCPT data using big DCP eqipment. Regression analysis and correlationship analysis were conducted with the data from relationship between SPT and DCPT. The analysis results showed that the convert fact are in the range of 1.12~1.31 with variation with soil property.

The Correlation Analysis between Dynamic Cone Penetration Test and Plate Loading Test Results for Evaluation of Dam Conditions (제체 상태 평가를 위한 동적 콘 관입시험과 평판재하시험 결과의 상관관계 분석)

  • Jung, Young-Hoon;Kim, Seongmin;Lim, Jeong-yeul
    • Journal of the Korean Geoenvironmental Society
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    • v.19 no.4
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    • pp.33-38
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    • 2018
  • The internal erosion due to poor compaction of the material was the main cause of collapse of the embankment in Korea. The assessment of the compaction state of the dam body was a very important check in the safety diagnosis of the embankment. In this study, the correlation between dynamic cone penetration test and plate loading test which is the most typical compaction evaluation technique was analyzed to verify the applicability of the dynamic cone penetration test in evaluating the compaction state of the dam body. The standard penetration tests were carried out six times to define soil properties and depth of the test site. The spatial distributions were obtained by the Kriging method after 15 times of plate loading tests and 47 times of dynamic cone penetration tests. The Pearson correlation coefficient between the spatial distribution of the plate loading test and the dynamic cone penetration test spatial distribution at the constant penetration depth was calculated. The load distribution in the plate loading test and the blow counts at penetration depths of 5 cm, 10 cm and 15 cm in the dynamic cone penetration test showed a weak positive correlation.

Development of Advanced Dynamic Cone Penetration Test Apparatus and Its Application Performance Evaluation (개량식 동적 콘 관입시험기의 개발 및 적용성 평가)

  • Kim, Uk-Gie;Zhuang, Li;Lee, Kwang-Wu
    • Journal of the Korean Geosynthetics Society
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    • v.13 no.4
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    • pp.119-131
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    • 2014
  • For quick and accurate ground investigation in wide construction site being not easy to access, advanced dynamic cone penetration test equipment was developed based on widely used equipment abroad. Advantages of existing equipment of portability and simple testing method were reflected in the new developed equipment. Meanwhile, by extending connection of lower rod, penetration depth is raised to 6m from 1 m of the existing equipment. Moreover, by assembly of hammer (2+3+3kg) and cone (3 types) etc., it is possible to perform test under the same conditions with those by German and Japan dynamic cone penetration test equipment (Tsukuba, PWRI and SH types). Auxiliary equipment was applied to make sure of perpendicularity as penetration depth increases. Applicability of the new developed equipment was evaluated through tests on various fields and its reliability was verified.

Evaluation of Active Layer Depth using Dynamic Cone Penetrometer (동적 콘 관입기를 이용한 활동층 심도평가)

  • Hong, Won-Taek;Kang, Seonghun;Park, Keunbo;Lee, Jong-Sub
    • Journal of the Korean Geoenvironmental Society
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    • v.17 no.1
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    • pp.49-54
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    • 2016
  • An active layer distributed on surface of an extreme cold region causes a frost heave by repeating the freezing and thawing according to the seasonal temperature change. Since the height of frost heave is greatly affected by the thickness of active layer, an accurate evaluation of the thickness of active layer is necessary for the safe design and construction of the infrastructure in the extreme cold region. In this study, dynamic cone penetrometer, which is miniaturized in-situ penetration device, is applied for the evaluation of active layer depth distribution. As the application tests, two dynamic cone penetration tests were conducted on the study sites located in Solomon and Alaska. In addition, ground temperature variations were obtained. As the results of the application tests, the depth of interface between the active layer and the permafrost was evaluated from the difference in dynamic cone penetration indexes of the active layer and the permafrost, and a layer was detected around the interface considered as an ice lens layer. Also, the interface depths between the above zero and the below zero temperature determined from the ground temperature variations correspond with the interface depths evaluated from the dynamic cone penetration tests. This study demonstrates that the dynamic cone penetrometer may be a useful tool for the evaluation of the active layer in the extreme cold region.

Shear Wave Velocity Estimation of Railway Roadbed Using Dynamic Cone Penetration Index (동적 콘 관입지수를 이용한 철도노반의 전단파속도 추정)

  • Hong, Won-Taek;Byun, Yong-Hoon;Choi, Chan Yong;Lee, Jong-Sub
    • Journal of the Korean Geotechnical Society
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    • v.31 no.11
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    • pp.25-31
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    • 2015
  • Elastic behavior of the railway roadbed which supports the repeating dynamic loads of the train is mainly affected by the shear modulus of the upper roadbed. Therefore, shear wave velocity estimation of the uniformly compacted roadbed can be used to estimate the elastic behavior of the railway roadbed. The objective of this study is to suggest the relationship between the dynamic cone penetration index (DCPI) and the shear wave velocity ($V_s$) of the upper roadbed in order to estimate the shear wave velocity by using the dynamic cone penetration test (DCPT). To ensure the reliability of the relationship, the dynamic cone penetration test and the measurement of the shear wave velocity are conducted on the constructed upper roadbed. As a method for measurement of the shear wave velocity, cross hole is used and then the dynamic cone penetration test is performed at a center point between the source and the receiver of the cross hole. As a result of the correlation of the dynamic cone penetration index and the shear wave velocity at the same depths, the shear wave velocity is estimated as a form of involution of the dynamic cone penetration index with a determinant coefficient above 0.8. The result of this study can be used to estimate both the shear wave velocity and the strength of the railway roadbed using the dynamic cone penetrometer.

A Mechanical Properties According to the Compaction Degree on Weathered Granite Soil Using Lightweight Dynamic Cone Penetrometer (경량 동적콘관입시험기를 이용한 화강풍화토의 다짐도에 따른 역학특성)

  • Kim, Yeon-Il;Kim, Jin-Young;Shim, Jae-Rok;Choi, Jin;Kang, Kwon-Soo;Baek, Won-Jin;Lee, Kang-Il
    • Journal of the Korean Geosynthetics Society
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    • v.13 no.3
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    • pp.21-30
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    • 2014
  • In this study, the applicability of the lightweight dynamic cone penetrometer in the domestic slope site was investigated using the weathered granite soil sampled form the Namwon slope site. And then, the lightweight dynamic cone penetration tests according to the change in the degree of compaction and water content were performed and it was analyzed with the correlations between the degree of compaction, the void ratio, the degree of saturation and the value of cone resistance. From the laboratory test results, the cone penetration resistance was rapidly increased in the dry side of the optimum moisture content, and it was largely decreased in the wet side of the optimum moisture content. Moreover, when the degree of compaction and the degree of saturation are large, the cone resistance is increased linearly. And a high correlativity was shown between water content, void ratio, the degree of saturation and the cone resistance. From these results, it is judged that the lightweight dynamic cone penetrometer can be applied to the investigation on the site slope.

Study on Shear Strength Using a Portable Dynamic Cone Penetration Test and Relationship between N-Nc (소형동적콘관입시험을 이용한 전단강도 산정 및 N-Nc 상관관계 연구)

  • Kim, Hyukho;Lim, Heuidae
    • Economic and Environmental Geology
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    • v.50 no.2
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    • pp.145-157
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    • 2017
  • Because of Recent intensive rainfall, nationally landslides and slope failure phenomenon has been frequently occur. Providing proposed-measures to the natural disasters that occur in these localities and the slope, must be derived ground of strength parameters(shear strength) as a design input data. However, it is such as extra deforestation and a lot of economic costs in order to make the access to the current area and the slopes ground survey is required. Thus, by small dynamic cone penetration test machine using the human to carry in the field, it is possible to easily measure the characteristics and strength constant of the ground of more than one region. In this study through researching analysis of the domestic and foreign small dynamic cone penetration test method, it has proposed a cone material and test methods suitable for the country. Cone penetration test Nc in the field has comparated with analysis of the value and the standard penetration test N value. And, in addition to this, direct shear test and borehole shear test were performed by depth, bedrock, and soil type and passing #200 and the correlation of the Nc value. In particular, in the present study, for the sandy soil that has distict distribute in mountain, it is proposed relation of shear strength corresponding to the Nc value (cohesion and internal friction angle) in order to calculate such effective ground shear strength.

Study on the Measurement of Liquid Limit Using a Penetration Resistance of Small Cone in Clay Soil (소형콘의 관입저항력을 이용한 점토의 액성한계측정에 관한 연구)

  • Son, Moorak;Lee, Jaeyong
    • Journal of the Korean Geotechnical Society
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    • v.32 no.10
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    • pp.5-15
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    • 2016
  • This study investigated both water content and penetration resistance of small cone of various clay soils that were made of Kaolinite and Bentonite with different mixing ratios and compared the results with those of the existing dynamic (Casagrande test) and static (fall cone test) tests directly. The comparison showed that the water content at the inflection point on a curve of water content and penetration resistance was very similar to the liquid limit from a fall cone test. The penetration resistance of small cone at the inflection point was 0.2 kPa, and it was ascertained that the water content at the inflection point represents a liquid limit of clay soils. From the study results, it was found that the penetration resistance of 0.2 kPa with the small cone can be an indicator of the liquid limit of clay soils in practice. Finally a test procedure to measure the liquid limit of clay soil based on a penetration resistance of small cone was proposed.

Comparison of Field Bearing Capacity Tests to Evaluate the Field Application of Dynamic Cone Penetrometer Test (동적 콘관입 시험의 현장적용성 평가를 위한 현장 지지력시험 상호 비교 연구)

  • Kim, Boo-Il;Jeon, Sung-Il;Lee, Moon-Sup
    • International Journal of Highway Engineering
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    • v.8 no.4
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    • pp.75-85
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    • 2006
  • Plate Bearing Test(PBT) and California Bearing Ratio Test(CBR) usually have been used to evaluate the bearing capacity of sub-layer in pavement system. However, these tests have shortcomings for which man powers and time are spent greatly. Many researchers proposed a simple Dynamic Cone Penetrometer Test(DCP) to evaluate the bearing capacity of sub-layers in pavement system. This study performed several field bearing capacity tests(DCP, PBT, CBR, FWD) to evaluate field performance of DCP on sub-base and subgrade at four test sections simultaneously. The results showed that DCPI, $M_{FWD}$, and $PBT_K_{30}$ are highly correlated, but CBR and other test are not. This study proposed the following regression models between FWD, DCP, and PBT: $$M_{FWD}=993.10\Big(\frac{1}{DCPI}\Big)+33.95\;R^2=0.77$$ $$M_{FWD}=3.7533K_{30}+23.085\;R^2=0.69$$

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Study on Establishing the Subgrade Compaction Control Methods Based on the In-situ Elastic Modulus (현장 탄성계수에 근거한 노상 다짐관리방안 연구)

  • Choi, Jun-Seong;Han, Jin-Seok;Kim, Jong-Min
    • International Journal of Highway Engineering
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    • v.14 no.3
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    • pp.49-58
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    • 2012
  • In many countries including Korea, the design concept of pavement structure has been converted from empirical method to mechanisticempirical method since the advent of compaction control based on resilient modulus proposed by AASHTO in 1986. Studies of last decades indicates that the classical compaction control method based on relative compaction and plate bearing test(PBT) will necessarily move to the methods taking advantage of light falling weight deflectometer(LFWD) and dynamic cone penetrometer(DCP) in addition to PBT. In this study, the validity of resilient modulus prediction equation proposed by Korean Pavement Design Guide is verified by comparison with physical properties of subgrade soil and the results of structural analysis. In addition, correlational equations between elastic modulus measured by various field tests and resilient modulus estimated by empirical model are proposed. Finally, a field test-based compaction control procedure for subgrade is suggested by using proposed correlational equations.