• Title, Summary, Keyword: Dynamic cone penetrometer

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Characterization of railway substructure using a hybrid cone penetrometer

  • Byun, Yong-Hoon;Hong, Won-Taek;Lee, Jong-Sub
    • Smart Structures and Systems
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    • v.15 no.4
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    • pp.1085-1101
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    • 2015
  • Changes in substructure conditions, such as ballast fouling and subgrade settlement may cause the railway quality deterioration, including the differential geometry of the rails. The objective of this study is to develop and apply a hybrid cone penetrometer (HCP) to characterize the railway substructure. The HCP consists of an outer rod and an inner mini cone, which can dynamically and statically penetrate the ballast and the subgrade, respectively. An accelerometer and four strain gauges are installed at the head of the outer rod and four strain gauges are attached at the tip of the inner mini cone. In the ballast, the outer rod provides a dynamic cone penetration index (DCPI) and the corrected DCPI (CDCPI) with the energy transferred into the rod head. Then, the inner mini cone is pushed to estimate the strength of the subgrade from the cone tip resistance. Laboratory application tests are performed on the specimen, which is prepared with gravel and sandy soil. In addition, the HCP is applied in the field and compared with the standard dynamic cone penetration test. The results from the laboratory and the field tests show that the cone tip resistance is inversely proportional to the CDCPI. Furthermore, in the subgrade, the HCP produces a high-resolution profile of the cone tip resistance and a profile of the CDCPI in the ballast. This study suggests that the dynamic and static penetration tests using the HCP may be useful for characterizing the railway substructure.

The Ground Investigation Technique of Railway Using Pagani Cone Test (Pagani Cone Test를 이용한 철도노반 조사 기법 연구)

  • Cho, Eun-Kyung;Cho, Kook-Hwan
    • Journal of the Korean Society for Railway
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    • v.19 no.6
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    • pp.792-801
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    • 2016
  • Standard Penetration Test (SPT) and Cone Penetration Test (CPT) are widely used in geotechnical investigation methods for railway roadbed. However, SPT can not be used on the Railway track, since the equipment may contact to the electric lines. However, a portable equipment can be used for geotechnical investigation without electrical hazard. Dynamic Cone Penetrometer (DCP) is one of representative portable equipments. A normal portable DCP has usually not enough driving energy and the rigidity of cone-rod, so it is impossible to investigate the required investigate penetration depth. In this study, The adaptability of Pagani cone test which is one of portable dynamic cone penetrometer is studied and compared with SPT-N data. As a result of this study, the proposed correlation factors between Pagani cone test and SPT-N values after corrections is 1.48 for sandy soil and 1.33 for clayey soil.

Estimation of Bearing Capacity of Subbase and Subgrade Using Pavement Dynamic Cone Penetrometer (포장동적관입시험기(PDCP)에 의한 보조기층 및 노상 지지력 측정)

  • Roo, Myung-Chan
    • International Journal of Highway Engineering
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    • v.5 no.1
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    • pp.35-45
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    • 2003
  • This paper presents a theoretical approach for estimation of CBR-value of subbase course and subgrade using a portable pavement dynamic cone penetrometer(PDCP). The PDCP used in this paper was based on a design from South Africa and extensive studies by Kleyn(1982) and more recently by Liveneh and Ishai(1987) and Chua(1988). To date, California Bearing Ratio[CBR] value was studied mainly for application of pavement structural design. This study was initiated to develop a method of obtaining the in situ CBR-values of subbase and subgrade for the structural evaluation of pavements in the swift and inexpensive manner. PDCP tests were implemented at 20 different kinds of soil samples in the lab and test results were analysed by a theoretical approach introduced. The procedure presented provides acceptable and promising results.

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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.

Bearing Capacity of Pavement Foundation by Waste Lime Material using the Dynamic Cone Pentrometer (동적 콘관입시험기를 이용한 폐석회 혼합 도로노반 성토체의 현장 지지력 평가)

  • Kim, Young-Seok;Hong, Seung-Seo;Bae, Gyu-Jin
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.2
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    • pp.927-935
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    • 2011
  • In-situ California Bearing Ratio(CBR) test has been widely used for evaluating the subgrade condition in pavements. However, because the in-situ CBR test is expensive and takes time for operation, it is difficult to figure out the in-situ characteristics of subgrade strength in detail. For faster and economical operation, the Dynamic Cone Penetrometer(DCP) has been often utilized for estimating the subgrade strength in the field. The purpose of this paper is to determine the relationship between CBR value and DCP index of the embankment constructed with mixtures of soil and waste lime. Waste lime used in this study is producted as a by-product in the manufacturing process of making $Na_2CO_3$ from local chemical factory in Incheon. In this field measurement, the geotechnical tests such as field water content, field density, field CBR test, and dynamic cone penetration test were conducted.

Application of The Dynamic Cone Penetrometer for Strength Estimation of Pavement Foundation (현장에서의 동적관입시험을 이용한 노상토의 지지력 평가연구)

  • An, Ji-Hwan;Yang, Sung-Lin;Park, Hee-Mun;Kwon, Su-Ahn
    • International Journal of Highway Engineering
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    • v.6 no.3
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    • pp.17-26
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    • 2004
  • The in-situ California Bearing Ratio (CBR) test has been widely used for evaluating the subgrade condition in asphalt concrete pavements. However, because the in-situ CBR test is expensive and takes plenty of time for operation, it is very difficult to figure out the in-situ characteristics of subgrade strength in detail. For faster and economical operation, the Dynamic Cone Penetrometer (DCP) has been often utilized for estimating the subgrade strength in the field. The relationship between the CBR value and DCP index obtained from the DCP testing has been studied using the laboratory and in-situ testing by other foreign researchers. The objective of this study is to determine the relationship between in-situ CBR value and DCP index of the subgrade materials used in Korea. The DCP index for evaluating the strength of subgrade materials produced in Korea is presented in this paper. Research results propose the regression equation to explain the relationship between the CBR and DCP tests. The in-situ CBR values of subgrade materials range from 20 to 45% indicating the good and sound subgrade condition.

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Cone penetrometer incorporated with dynamic cone penetration method for investigation of track substructures

  • Hong, Won-Taek;Byun, Yong-Hoon;Kim, Sang Yeob;Lee, Jong-Sub
    • Smart Structures and Systems
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    • v.18 no.2
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    • pp.197-216
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    • 2016
  • The increased speed of a train causes increased loads that act on the track substructures. To ensure the safety of the track substructures, proper maintenance and repair are necessary based on an accurate characterization of strength and stiffness. The objective of this study is to develop and apply a cone penetrometer incorporated with the dynamic cone penetration method (CPD) for investigating track substructures. The CPD consists of an outer rod for dynamic penetration in the ballast layer and an inner rod with load cells for static penetration in the subgrade. Additionally, an energy-monitoring module composed of strain gauges and an accelerometer is connected to the head of the outer rod to measure the dynamic responses during the dynamic penetration. Moreover, eight strain gauges are installed in the load cells for static penetration to measure the cone tip resistance and the friction resistance during static penetration. To investigate the applicability of the developed CPD, laboratory and field tests are performed. The results of the CPD tests, i.e., profiles of the corrected dynamic cone penetration index (CDI), profiles of the cone tip and friction resistances, and the friction ratio are obtained at high resolution. Moreover, the maximum shear modulus of the subgrade is estimated using the relationships between the static penetration resistances and the maximum shear modulus obtained from the laboratory tests. This study suggests that the CPD test may be a useful method for the characterization of track substructures.

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.

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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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.