The Experts below are selected from a list of 3399 Experts worldwide ranked by ideXlab platform

Jong-sub Lee - One of the best experts on this subject based on the ideXlab platform.

  • stiffness evaluation of compacted geo materials using crosshole type dynamic Cone Penetrometer cdp rplt and lfwd
    Construction and Building Materials, 2021
    Co-Authors: Jong-sub Lee, Erol Tutumluer, Won Taek Hong
    Abstract:

    Abstract Evaluation of the strength and stiffness of compacted geo-materials is required to ensure that it has sufficient bearing capacity and stiffness to the acting loads. In this study, a crosshole-type dynamic Cone Penetrometer (CDP) was applied to investigate the strength and stiffness characteristics of a compacted subgrade. The CDP characterizes the subgrade strength by the penetration index (CDPI) and evaluates the stiffness by the shear wave velocity (Vs) and maximum shear modulus (Gmax). CDP tests were conducted at three testing points. Repetitive plate loading tests (rPLTs) and light falling weight deflectometer (LFWD) tests were conducted as standard testing methods for the stiffness estimation of the subgrade. Experimental results show that while the rPLT and LFWD evaluate the equivalent elastic moduli (Ev1, Ev2, and Evd) within the influence zone, the CDP provides the CDPI, Vs, and Gmax along the depth. Linear relationships between the Gmax and the equivalent elastic moduli are constructed. The strain levels corresponding to Ev1, Ev2, and Evd are estimated. This study demonstrates that the CDP is an effective testing method for both strength and stiffness evaluations of the subgrade along the depth.

  • subgrade assessment using automated dynamic Cone Penetrometer to manage geo infrastructures
    Smart Structures and Systems, 2021
    Co-Authors: Sangyeob Kim, Jong-sub Lee, Won Taek Hong
    Abstract:

    For the efficient management of geo-infrastructures in the field, engineering properties of the subgrade should be reliably and rapidly investigated. The objective of this study is to estimate and compare the strength and stiffness parameters of subgrades using portable in-situ devices. An automated dynamic Cone Penetrometer (ACP), dynamic Cone Penetrometer (DCP), and light falling weight deflectometer (LFWD) are adopted and applied at nine points of soft ground in South Korea. The Nvalue from the ACP (NACP), which efficiently assesses the relatively deep subgrade, is correlated with the dynamic Cone penetration index (DCPI) and dynamic deflection modulus (Evd). Test results show that the DCPI and Evd can be estimated in terms of NACP. In particular, the relationship between Evd and NACP is improved when the strain influence factor of the target ground is considered. For the assessment of strength and stiffness parameters, the California bearing ratio (CBR), relative density (Dr), internal friction angle (φ), and elastic moduli determined by the plate loading test (PLT), soil stiffness gauge (SSG), falling weight deflectometer (FWD) are estimated using NACP. The ACP test with the relationships between engineering parameters and NACP may be an effectively method to assess the overall characteristics of the subgrade.

  • comparative study on estimation methods of dynamic resistance using dynamic Cone Penetrometer
    Sensors, 2021
    Co-Authors: Sangyeob Kim, Jong-sub Lee, Dongju Kim, Yong Hoon Byun
    Abstract:

    Dynamic resistance, which can be used to express strength in the unit of stress and improve the reliability of the dynamic Cone penetration test (DCPT), has been estimated by numerous methods. This study aims to compare different dynamic resistance estimation methods by using an instrumented dynamic Cone Penetrometer (IDCP). DCPTs are conducted using a standard dynamic Cone Penetrometer (DCP) and IDCP in the laboratory and field. Dynamic responses are obtained from the strain gauges and an accelerometer installed at the Cone tip of the IDCP. The test results show that dynamic resistance is more efficient in distinguishing profiles than the dynamic Cone penetration index. Among the methods to estimate the dynamic resistance at the Cone tip, the force-velocity integration method and force integration method are more related to the conventional dynamic resistance considering the potential energy of the hammer than the force squared integration method. Additionally, the dynamic resistance estimated for a longer time period is more reliable, particularly for small driving rod lengths. Regarding the limitation of the dynamic response from an accelerometer in a previous study, the force-based dynamic resistance estimated for a longer time period can be used as the most reliable approach for further soil strength characterization.

  • Instrumented Cone Penetrometer for Dense Layer Characterization.
    Sensors, 2020
    Co-Authors: Jong-sub Lee, Yong Hoon Byun
    Abstract:

    Subsurface characterization is essential for a successful infrastructure design and construction. This paper demonstrates the use of an instrumented Cone Penetrometer (ICP) for a dense layer characterization at two sites. The ICP consists of a Cone tip and rods equipped with an accelerometer and four strain gauges, which allow dynamic driving, in addition to quasi-static pushing of the Cone. The force and velocity of the Cone are measured using the ICP instrumentation and compared with the N value, dynamic Cone penetration index, and static Cone resistance. A strong correlation has been observed between the total Cone resistance estimated from the ICP and the dynamic Cone penetration index and static Cone resistance. After the correction of the dynamic Cone resistance effect, the static component of the total Cone resistance can be used as an alternative to a static Cone resistance. This novel approach of soil resistance estimation using the ICP may be useful for dense layer characterization.

  • dynamic Cone Penetrometer incorporated with time domain reflectometry tdr sensors for the evaluation of water contents in sandy soils
    Sensors, 2019
    Co-Authors: Won Taek Hong, Sangyeob Kim, Jong-sub Lee
    Abstract:

    Ground moisture content and strength properties are the most important factors for a proper assessment of ground stability. This study developed a dynamic Cone Penetrometer incorporated with time domain reflectometry (TDR) sensors (TDCP). The TDCP is composed of an anvil, a driving rod, and a TDCP probe. Three wave guides and a K-type thermocouple are installed on the TDCP probe. For utilization of TDCP, relationships between relative permittivities measured by TDCP and those measured by standard TDR probe, temperature, and volumetric water content of the soils were investigated. In addition, the relationship between penetration indices by TDCP (TPI) and by standard dynamic Cone Penetrometer was established. In the field application test, relative permittivity, ground temperature, and TPI were measured along the depth. Moreover, gravimetric water contents were also measured for comparison. The experimental results showed that volumetric water contents compensated by ground temperature showed good agreement with the volumetric water contents estimated from the gravimetric water contents of the soil samples and TPI. This study suggests that the TDCP may be effectively used for the evaluation moisture contents and for the strength characterization of the subsurface.

Won Taek Hong - One of the best experts on this subject based on the ideXlab platform.

  • stiffness evaluation of compacted geo materials using crosshole type dynamic Cone Penetrometer cdp rplt and lfwd
    Construction and Building Materials, 2021
    Co-Authors: Jong-sub Lee, Erol Tutumluer, Won Taek Hong
    Abstract:

    Abstract Evaluation of the strength and stiffness of compacted geo-materials is required to ensure that it has sufficient bearing capacity and stiffness to the acting loads. In this study, a crosshole-type dynamic Cone Penetrometer (CDP) was applied to investigate the strength and stiffness characteristics of a compacted subgrade. The CDP characterizes the subgrade strength by the penetration index (CDPI) and evaluates the stiffness by the shear wave velocity (Vs) and maximum shear modulus (Gmax). CDP tests were conducted at three testing points. Repetitive plate loading tests (rPLTs) and light falling weight deflectometer (LFWD) tests were conducted as standard testing methods for the stiffness estimation of the subgrade. Experimental results show that while the rPLT and LFWD evaluate the equivalent elastic moduli (Ev1, Ev2, and Evd) within the influence zone, the CDP provides the CDPI, Vs, and Gmax along the depth. Linear relationships between the Gmax and the equivalent elastic moduli are constructed. The strain levels corresponding to Ev1, Ev2, and Evd are estimated. This study demonstrates that the CDP is an effective testing method for both strength and stiffness evaluations of the subgrade along the depth.

  • subgrade assessment using automated dynamic Cone Penetrometer to manage geo infrastructures
    Smart Structures and Systems, 2021
    Co-Authors: Sangyeob Kim, Jong-sub Lee, Won Taek Hong
    Abstract:

    For the efficient management of geo-infrastructures in the field, engineering properties of the subgrade should be reliably and rapidly investigated. The objective of this study is to estimate and compare the strength and stiffness parameters of subgrades using portable in-situ devices. An automated dynamic Cone Penetrometer (ACP), dynamic Cone Penetrometer (DCP), and light falling weight deflectometer (LFWD) are adopted and applied at nine points of soft ground in South Korea. The Nvalue from the ACP (NACP), which efficiently assesses the relatively deep subgrade, is correlated with the dynamic Cone penetration index (DCPI) and dynamic deflection modulus (Evd). Test results show that the DCPI and Evd can be estimated in terms of NACP. In particular, the relationship between Evd and NACP is improved when the strain influence factor of the target ground is considered. For the assessment of strength and stiffness parameters, the California bearing ratio (CBR), relative density (Dr), internal friction angle (φ), and elastic moduli determined by the plate loading test (PLT), soil stiffness gauge (SSG), falling weight deflectometer (FWD) are estimated using NACP. The ACP test with the relationships between engineering parameters and NACP may be an effectively method to assess the overall characteristics of the subgrade.

  • dynamic Cone Penetrometer incorporated with time domain reflectometry tdr sensors for the evaluation of water contents in sandy soils
    Sensors, 2019
    Co-Authors: Won Taek Hong, Sangyeob Kim, Jong-sub Lee
    Abstract:

    Ground moisture content and strength properties are the most important factors for a proper assessment of ground stability. This study developed a dynamic Cone Penetrometer incorporated with time domain reflectometry (TDR) sensors (TDCP). The TDCP is composed of an anvil, a driving rod, and a TDCP probe. Three wave guides and a K-type thermocouple are installed on the TDCP probe. For utilization of TDCP, relationships between relative permittivities measured by TDCP and those measured by standard TDR probe, temperature, and volumetric water content of the soils were investigated. In addition, the relationship between penetration indices by TDCP (TPI) and by standard dynamic Cone Penetrometer was established. In the field application test, relative permittivity, ground temperature, and TPI were measured along the depth. Moreover, gravimetric water contents were also measured for comparison. The experimental results showed that volumetric water contents compensated by ground temperature showed good agreement with the volumetric water contents estimated from the gravimetric water contents of the soil samples and TPI. This study suggests that the TDCP may be effectively used for the evaluation moisture contents and for the strength characterization of the subsurface.

  • Assessing subgrade strength using an instrumented dynamic Cone Penetrometer
    Soils and Foundations, 2019
    Co-Authors: Jong-sub Lee, Sangyeob Kim, Won Taek Hong, Yong Hoon Byun
    Abstract:

    Abstract Subgrade strength is an important aspect to be considered when designing unsurfaced roads and working platforms for pavement structures. Furthermore, dynamic Cone penetration tests are used to characterize the subgrade strength. However, the results of dynamic Cone penetration tests, including the penetration depth per blow, can be affected by transferred energy and the verticality of the Cone Penetrometer. The objective of this paper is to characterize the subgrade strength using an instrumented dynamic Cone Penetrometer (DCP). The instrumented DCP includes a load cell and an accelerometer, located on the Cone tip, and measures the dynamic responses of force and velocity over elapsed time. Weathered soil is compacted with three different dry unit weights in a square-shaped container for lab-scale dynamic Cone penetration tests. Using instrumented and standard DCPs, several dynamic Cone penetration tests are performed, and the dynamic Cone penetration index (DCPI) is recorded along the depth profiles. Based on the dynamic responses at the Cone tip of the instrumented DCP and the principles of energy conservation, the dynamic Cone resistance is suggested as a new strength index. The experimental results show that the dynamic Cone resistance increases with the depth of the instrumented DCP, providing a reliable subgrade strength profile in the soil. In addition, the correlation between the DCPI obtained from the instrumented DCP and the dynamic Cone resistance suggests that the dynamic Cone resistance is more sensitive than the DCPI for stiff soil. Based on the correlation values of the dynamic Cone resistance obtained from the instrumented DCP, the internal friction angle and California bearing ratio values can be estimated with a high degree of reliability. This study demonstrates that use of the instrumented DCP may be a promising in situ testing method for the reliable characterization of subgrade strength.

  • strength and stiffness assessment of railway track substructures using crosshole type dynamic Cone Penetrometer
    Soil Dynamics and Earthquake Engineering, 2017
    Co-Authors: Won Taek Hong, Sangyeob Kim, Sung Jin Lee, Jong-sub Lee
    Abstract:

    Abstract To ensure safe train services, an effective method is required for the characterization of the strength and stiffness of railway track substructures. In this study, a crosshole-type dynamic Cone Penetrometer (CDP) is developed to characterize the strength by the crosshole-type dynamic Cone penetration index (CDPI) and stiffness by the shear wave velocity (Vs). To verify the Vs obtained using the CDP test, the Vs obtained by both CDP and bender elements are compared in a chamber test. In addition, for the characterization of the railway track substructures, field tests are conducted. The chamber test shows that the Vs obtained using the CDP are almost the same as those obtained by bender elements. In field tests, the CDPI and the Vs are profiled along the depth, the including ballast, sub-ballast, and subgrade layers, which are identified by ground penetrating radar surveys. As the CDPI is highly correlated to the Vs, the stiffness characteristics are considered to be reasonable and can be simply estimated using the CDPI. This study demonstrates that the CDP test can be used for the evaluation of the strength characteristics and small strain elastic properties of the track substructures.

Yong Hoon Byun - One of the best experts on this subject based on the ideXlab platform.

  • comparative study on estimation methods of dynamic resistance using dynamic Cone Penetrometer
    Sensors, 2021
    Co-Authors: Sangyeob Kim, Jong-sub Lee, Dongju Kim, Yong Hoon Byun
    Abstract:

    Dynamic resistance, which can be used to express strength in the unit of stress and improve the reliability of the dynamic Cone penetration test (DCPT), has been estimated by numerous methods. This study aims to compare different dynamic resistance estimation methods by using an instrumented dynamic Cone Penetrometer (IDCP). DCPTs are conducted using a standard dynamic Cone Penetrometer (DCP) and IDCP in the laboratory and field. Dynamic responses are obtained from the strain gauges and an accelerometer installed at the Cone tip of the IDCP. The test results show that dynamic resistance is more efficient in distinguishing profiles than the dynamic Cone penetration index. Among the methods to estimate the dynamic resistance at the Cone tip, the force-velocity integration method and force integration method are more related to the conventional dynamic resistance considering the potential energy of the hammer than the force squared integration method. Additionally, the dynamic resistance estimated for a longer time period is more reliable, particularly for small driving rod lengths. Regarding the limitation of the dynamic response from an accelerometer in a previous study, the force-based dynamic resistance estimated for a longer time period can be used as the most reliable approach for further soil strength characterization.

  • Instrumented Cone Penetrometer for Dense Layer Characterization.
    Sensors, 2020
    Co-Authors: Jong-sub Lee, Yong Hoon Byun
    Abstract:

    Subsurface characterization is essential for a successful infrastructure design and construction. This paper demonstrates the use of an instrumented Cone Penetrometer (ICP) for a dense layer characterization at two sites. The ICP consists of a Cone tip and rods equipped with an accelerometer and four strain gauges, which allow dynamic driving, in addition to quasi-static pushing of the Cone. The force and velocity of the Cone are measured using the ICP instrumentation and compared with the N value, dynamic Cone penetration index, and static Cone resistance. A strong correlation has been observed between the total Cone resistance estimated from the ICP and the dynamic Cone penetration index and static Cone resistance. After the correction of the dynamic Cone resistance effect, the static component of the total Cone resistance can be used as an alternative to a static Cone resistance. This novel approach of soil resistance estimation using the ICP may be useful for dense layer characterization.

  • Assessing subgrade strength using an instrumented dynamic Cone Penetrometer
    Soils and Foundations, 2019
    Co-Authors: Jong-sub Lee, Sangyeob Kim, Won Taek Hong, Yong Hoon Byun
    Abstract:

    Abstract Subgrade strength is an important aspect to be considered when designing unsurfaced roads and working platforms for pavement structures. Furthermore, dynamic Cone penetration tests are used to characterize the subgrade strength. However, the results of dynamic Cone penetration tests, including the penetration depth per blow, can be affected by transferred energy and the verticality of the Cone Penetrometer. The objective of this paper is to characterize the subgrade strength using an instrumented dynamic Cone Penetrometer (DCP). The instrumented DCP includes a load cell and an accelerometer, located on the Cone tip, and measures the dynamic responses of force and velocity over elapsed time. Weathered soil is compacted with three different dry unit weights in a square-shaped container for lab-scale dynamic Cone penetration tests. Using instrumented and standard DCPs, several dynamic Cone penetration tests are performed, and the dynamic Cone penetration index (DCPI) is recorded along the depth profiles. Based on the dynamic responses at the Cone tip of the instrumented DCP and the principles of energy conservation, the dynamic Cone resistance is suggested as a new strength index. The experimental results show that the dynamic Cone resistance increases with the depth of the instrumented DCP, providing a reliable subgrade strength profile in the soil. In addition, the correlation between the DCPI obtained from the instrumented DCP and the dynamic Cone resistance suggests that the dynamic Cone resistance is more sensitive than the DCPI for stiff soil. Based on the correlation values of the dynamic Cone resistance obtained from the instrumented DCP, the internal friction angle and California bearing ratio values can be estimated with a high degree of reliability. This study demonstrates that use of the instrumented DCP may be a promising in situ testing method for the reliable characterization of subgrade strength.

  • Cone Penetrometer incorporated with dynamic Cone penetration method for investigation of track substructures
    Smart Structures and Systems, 2016
    Co-Authors: Won Taek Hong, Yong Hoon Byun, Sangyeob Kim, Jong-sub Lee
    Abstract:

    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.

  • active layer characterization by instrumented dynamic Cone Penetrometer in ny alesund svalbard
    Cold Regions Science and Technology, 2014
    Co-Authors: Yong Hoon Byun, Hyung-koo Yoon, Youngseok Kim, Seung Seo Hong, Jong-sub Lee
    Abstract:

    Abstract Global warming may induce an increase of active layer thickness in the Arctic region. The freezing and thawing of the active layer can damage infrastructures such as roads, railways, and embedded pipe lines in cold regions. A few methods, however, have been proposed to characterize the active layer. The objective of this study is to evaluate the characteristics of the active layer by laboratory and field tests, especially using the instrumented dynamic Cone Penetrometer (IDCP). Geographical and geological characteristics of Ny-Alesund, Svalbard are introduced, and the geotechnical properties, microstructure observations, and thermal properties of the Ny-Alesund soils are investigated. In addition, subsurface temperatures monitored for a year are discussed. The IDCP, which is able to measure the energies transferred into the rod head and the Cone tip, is applied to the evaluation of the strength variation and the thickness of the active layer in Ny-Alesund. During dynamic penetration tests, the IDCP can produce profiles of the corrected Cone tip resistance as well as the dynamic Cone penetration index (DCPI). The results show that the active layer thickness estimated from the DCPI and corrected Cone tip resistance profiles is approximately 1700 mm. Furthermore, the bottom of the active layer significantly corresponds to that estimated by the maximum ground temperature profile with a soil thermal diffusivity of 5.5 · 10− 7 m2·s− 1. This study represents the characteristics of Ny-Alesund soils investigated with a variety of laboratory tests, and suggests that the IDCP may be effectively used for active layer characterization.

Sangyeob Kim - One of the best experts on this subject based on the ideXlab platform.

  • subgrade assessment using automated dynamic Cone Penetrometer to manage geo infrastructures
    Smart Structures and Systems, 2021
    Co-Authors: Sangyeob Kim, Jong-sub Lee, Won Taek Hong
    Abstract:

    For the efficient management of geo-infrastructures in the field, engineering properties of the subgrade should be reliably and rapidly investigated. The objective of this study is to estimate and compare the strength and stiffness parameters of subgrades using portable in-situ devices. An automated dynamic Cone Penetrometer (ACP), dynamic Cone Penetrometer (DCP), and light falling weight deflectometer (LFWD) are adopted and applied at nine points of soft ground in South Korea. The Nvalue from the ACP (NACP), which efficiently assesses the relatively deep subgrade, is correlated with the dynamic Cone penetration index (DCPI) and dynamic deflection modulus (Evd). Test results show that the DCPI and Evd can be estimated in terms of NACP. In particular, the relationship between Evd and NACP is improved when the strain influence factor of the target ground is considered. For the assessment of strength and stiffness parameters, the California bearing ratio (CBR), relative density (Dr), internal friction angle (φ), and elastic moduli determined by the plate loading test (PLT), soil stiffness gauge (SSG), falling weight deflectometer (FWD) are estimated using NACP. The ACP test with the relationships between engineering parameters and NACP may be an effectively method to assess the overall characteristics of the subgrade.

  • comparative study on estimation methods of dynamic resistance using dynamic Cone Penetrometer
    Sensors, 2021
    Co-Authors: Sangyeob Kim, Jong-sub Lee, Dongju Kim, Yong Hoon Byun
    Abstract:

    Dynamic resistance, which can be used to express strength in the unit of stress and improve the reliability of the dynamic Cone penetration test (DCPT), has been estimated by numerous methods. This study aims to compare different dynamic resistance estimation methods by using an instrumented dynamic Cone Penetrometer (IDCP). DCPTs are conducted using a standard dynamic Cone Penetrometer (DCP) and IDCP in the laboratory and field. Dynamic responses are obtained from the strain gauges and an accelerometer installed at the Cone tip of the IDCP. The test results show that dynamic resistance is more efficient in distinguishing profiles than the dynamic Cone penetration index. Among the methods to estimate the dynamic resistance at the Cone tip, the force-velocity integration method and force integration method are more related to the conventional dynamic resistance considering the potential energy of the hammer than the force squared integration method. Additionally, the dynamic resistance estimated for a longer time period is more reliable, particularly for small driving rod lengths. Regarding the limitation of the dynamic response from an accelerometer in a previous study, the force-based dynamic resistance estimated for a longer time period can be used as the most reliable approach for further soil strength characterization.

  • dynamic Cone Penetrometer incorporated with time domain reflectometry tdr sensors for the evaluation of water contents in sandy soils
    Sensors, 2019
    Co-Authors: Won Taek Hong, Sangyeob Kim, Jong-sub Lee
    Abstract:

    Ground moisture content and strength properties are the most important factors for a proper assessment of ground stability. This study developed a dynamic Cone Penetrometer incorporated with time domain reflectometry (TDR) sensors (TDCP). The TDCP is composed of an anvil, a driving rod, and a TDCP probe. Three wave guides and a K-type thermocouple are installed on the TDCP probe. For utilization of TDCP, relationships between relative permittivities measured by TDCP and those measured by standard TDR probe, temperature, and volumetric water content of the soils were investigated. In addition, the relationship between penetration indices by TDCP (TPI) and by standard dynamic Cone Penetrometer was established. In the field application test, relative permittivity, ground temperature, and TPI were measured along the depth. Moreover, gravimetric water contents were also measured for comparison. The experimental results showed that volumetric water contents compensated by ground temperature showed good agreement with the volumetric water contents estimated from the gravimetric water contents of the soil samples and TPI. This study suggests that the TDCP may be effectively used for the evaluation moisture contents and for the strength characterization of the subsurface.

  • Assessing subgrade strength using an instrumented dynamic Cone Penetrometer
    Soils and Foundations, 2019
    Co-Authors: Jong-sub Lee, Sangyeob Kim, Won Taek Hong, Yong Hoon Byun
    Abstract:

    Abstract Subgrade strength is an important aspect to be considered when designing unsurfaced roads and working platforms for pavement structures. Furthermore, dynamic Cone penetration tests are used to characterize the subgrade strength. However, the results of dynamic Cone penetration tests, including the penetration depth per blow, can be affected by transferred energy and the verticality of the Cone Penetrometer. The objective of this paper is to characterize the subgrade strength using an instrumented dynamic Cone Penetrometer (DCP). The instrumented DCP includes a load cell and an accelerometer, located on the Cone tip, and measures the dynamic responses of force and velocity over elapsed time. Weathered soil is compacted with three different dry unit weights in a square-shaped container for lab-scale dynamic Cone penetration tests. Using instrumented and standard DCPs, several dynamic Cone penetration tests are performed, and the dynamic Cone penetration index (DCPI) is recorded along the depth profiles. Based on the dynamic responses at the Cone tip of the instrumented DCP and the principles of energy conservation, the dynamic Cone resistance is suggested as a new strength index. The experimental results show that the dynamic Cone resistance increases with the depth of the instrumented DCP, providing a reliable subgrade strength profile in the soil. In addition, the correlation between the DCPI obtained from the instrumented DCP and the dynamic Cone resistance suggests that the dynamic Cone resistance is more sensitive than the DCPI for stiff soil. Based on the correlation values of the dynamic Cone resistance obtained from the instrumented DCP, the internal friction angle and California bearing ratio values can be estimated with a high degree of reliability. This study demonstrates that use of the instrumented DCP may be a promising in situ testing method for the reliable characterization of subgrade strength.

  • strength and stiffness assessment of railway track substructures using crosshole type dynamic Cone Penetrometer
    Soil Dynamics and Earthquake Engineering, 2017
    Co-Authors: Won Taek Hong, Sangyeob Kim, Sung Jin Lee, Jong-sub Lee
    Abstract:

    Abstract To ensure safe train services, an effective method is required for the characterization of the strength and stiffness of railway track substructures. In this study, a crosshole-type dynamic Cone Penetrometer (CDP) is developed to characterize the strength by the crosshole-type dynamic Cone penetration index (CDPI) and stiffness by the shear wave velocity (Vs). To verify the Vs obtained using the CDP test, the Vs obtained by both CDP and bender elements are compared in a chamber test. In addition, for the characterization of the railway track substructures, field tests are conducted. The chamber test shows that the Vs obtained using the CDP are almost the same as those obtained by bender elements. In field tests, the CDPI and the Vs are profiled along the depth, the including ballast, sub-ballast, and subgrade layers, which are identified by ground penetrating radar surveys. As the CDPI is highly correlated to the Vs, the stiffness characteristics are considered to be reasonable and can be simply estimated using the CDPI. This study demonstrates that the CDP test can be used for the evaluation of the strength characteristics and small strain elastic properties of the track substructures.

Choon Peng Tee - One of the best experts on this subject based on the ideXlab platform.

  • improvements in nuclear density Cone Penetrometer for non homogeneous soils
    Soils and Foundations, 2007
    Co-Authors: Muthusamy Karthikeyan, Thiamsoon Tan, Mamoru Mimura, Mitsugu Yoshimura, Choon Peng Tee
    Abstract:

    In Singapore, the use of clays from marine dredging and land-based construction activities as fill for land reclamation provides a solution to the problem of disposal while turning such unwanted soils into material of economic value. A major problem with such fill is the formation of very high degree of heterogeneity in the ground. The characterization of such ground at different stages of land reclamation works poses a major challenge as many traditional in-situ tests which provide point values are based on solutions derived assuming the ground is a continuum. A major site characterization program was carried out as part of a research project. The Nuclear-Density Cone Penetrometer is employed for site investigation to measure the continuous changes in density together with other usual Cone parameters. The tests have been conducted at various stages of land reclamation works. In the present paper, the problems faced in marine based investigations associated with the use of an existing Double Probe Nuclear-Density Cone Penetrometer are briefly discussed and this limitation has led to the development of a new Single Probe Nuclear-Density Cone Penetrometer which is the main focus of this paper. The wet density profiles obtained from the Single Probe Nuclear-Density Cone Penetrometer are compared with the double probe and the comparison shows a very good agreement.