• Title/Summary/Keyword: Dynamic cone penetration

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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.

Analysis of Application Cases and Evaluation of Effectiveness on Portable Dynamic Cone Penetration Test (DCPT) to Identify the Deterioration Cause of Damaged Reinforced Earth Walls (보강토옹벽의 피해원인 규명을 위한 휴대형 동적콘관입시험(DCPT) 적용사례 분석 및 효용성 평가)

  • Lee, Kwang-Wu;Cho, Sam-Deok
    • Journal of the Korean Geosynthetics Society
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    • v.19 no.4
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    • pp.95-109
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    • 2020
  • In this study, a total of six site cases were reviewed to assess the site applicability of portable dynamic cone penetration test (DCPT) by identifying the cause of damage to the damaged reinforced earth wall using portable dynamic cone penetration test. An improved dynamic concrete penetration tester was used at the site to enable ground surveys of more than 6 meters. The test results were compared with the results of the standard penetration test (SPT) and the correlation was analyzed. Through the analysis of various field application cases, it was found that portable dynamic cone penetration test was very convenient to apply at the site of the damaged reinforced earth wall, and DCPT could play a major role in identifying the cause of damage and verifying stability of the retaining wall by continuously identifying the ground strength. In addition, it was found that the results of the dynamic cone penetration test and the standard penetration test showed a correlation of N≒(1/3~2/3)·Nd in sandy soil.

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.

Development of Dynamic Cone Penetration Tester Module for Slope Vulnerability Assessment and Correlation of Its Results with Standard Penetration Test Values (비탈면 취약도 평가를 위한 동적콘관입시험기 모듈개발과 표준관입시험값과의 상관관계 연구)

  • Chae, Hwi-Young;Kwon, Soon-dal
    • The Journal of Engineering Geology
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    • v.31 no.4
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    • pp.541-547
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    • 2021
  • To assess the stability of a slope and the likelihood of its loss or collapse requires information about the ground, such as the composition of the stratum and its mechanical characteristics. This information is generally gathered through standard penetration testing (SPT) and cone penetration testing. SPT is not widely used due to problems with accessing slopes, most of which are steep and without ramps. A drop cone penetrometer, a portable device that can make up for these shortcomings, can be used in a limited way in some circumstances. Therefore, we developed a portable drilling machine and a small dynamic cone penetration test module that can easily access a slope site and perform SPT. The correlation of the developed system's results with those from SPT was analyzed. Analysis of the correlation between the energy shear rate passing to the load during the different test types established that the energy shear rate is reflected in the test result. The correlation between corrected dynamic cone penetration testing and corrected SPT was Nd' = 3.13 N'.

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.

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 GEO-environmental 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.

A Study on the Field Application of a Small Dynamic Cone Penetration Tester Using Hammer Automatic Strike and Penetration Measurement (해머 타격과 관입량 측정이 자동화된 소형 동적콘관입시험기의 현장 적용성 연구)

  • Hwiyoung Chae ;Soondal Kwon
    • Journal of the Korean GEO-environmental Society
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    • v.24 no.12
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    • pp.5-11
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    • 2023
  • Economic damage is occurring due to landslides and debris flows that occur when the ground artificially created for roads or photovoltaic power generation facilities is weakened by rainfall such as torrential rain. In order to understand the stability of the artificially created ground, it is very important to check the ground information such as the compositional state and mechanical characteristics of the stratum. However, since most of the investigation sites are steep slopes or there are no access roads, it is not easy to enter the drilling equipment commonly used to check ground information and perform standard penetration tests. In this study, a dynamic cone penetration test (DCP) device using a miniaturized auger drilling equipment and an automatic drop device was developed to check the cone resistance value and the dynamic cone penetration test value and analyze the correlation with the standard penetration test value to confirm its applicability at the mountain solar power generation site. As a result, the cone resistance value is qd = 0.46 N and the dynamic cone penetration test value is Nd = 1.58 N, confirming a value similar to the results of existing researchers to secure its reliability.

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.

Study on Correlation between Dynamic Cone Resistance and Shear Strength for Frozen Sand-Silt Mixtures under Low Confining Stress (낮은 구속응력에서 모래-실트 혼합토의 동결강도 평가를 위한 동적 콘 저항력 및 전단강도 상관성 연구)

  • Kim, Sangyeob;Lee, Jong-Sub;Hong, Seungseo;Byun, Yong-Hoon
    • Journal of the Korean GEO-environmental Society
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    • v.17 no.1
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    • pp.5-12
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    • 2016
  • Investigation of in-situ ground in cold region is difficult due to low accessibility and environmental factors. In this study, correlation between dynamic cone resistance and shear strength is suggested to estimate the strength of frozen soils by using instrumented dynamic cone penetrometer. Tests were conducted in freezing chamber after preparing sand-silt mixture with 2.3% water content. Vertical stresses of 5 kPa and 10 kPa were applied during freezing, shearing, and penetration phase to compare the dynamic cone resistance and shear strength. The dynamic cone resistance, additionally, is calculated to minimize the effect of energy loss during hammer impact. Experimental results show that as the shear strength increases, the dynamic cone penetration index (DCPI) decreases nonlinearly, while the dynamic cone resistance increases linearly. This study provides the useful correlation to evaluate strength properties of the frozen soils from the dynamic cone penetration and direct shear tests.

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.