• Journal of the Korean GEO-environmental Society
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• v.7 no.5
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• pp.13-20
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• 2006

We have conducted standard penetration tests and static cone penetration tests that are widely used the land base examination on the soft ground subsurface of Yongdong area, and examined the correlation between them. We have also made a comparative analysis of the correlation between the indoor tests on the materials collected on the site and on-the-spot penetration tests. The results are as follows : The relationship between Standard Penetration Test N-value and Dutch Cone Tset show $Q_c=1.93N+0.29$ for organic soil, $Q_c=2.19N+0.20$ for clay, $Q_c=2.34N+1.06$ for silt, $Q_c=3.02N+0.54$ for silty sand, and $Q_c=3.47N+0.46$ for sand. In this case of sand $Q_c/N$ increases when the soil particles are larger. The relationship between standard penetration test N-value and Unconfined Compression Strength $q_u$ show $q_u=0.11N+0.03$ for organic soil, $q_u=0.11N+0.25$ for clay, and $q_u=0.18N-0.03$ for silt.

• Journal of the Korean Geotechnical Society
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• v.25 no.10
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• pp.31-40
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• 2009

As the measurement of strain-gage type cone penetrometer is influenced by the temperature change during penetration, the temperature is a factor producing an error of the cone tip resistance. In this study, the 0.5 mm diameter temperature transducer and 7 mm diameter micro cone penetrometer are manufactured by using FBG sensors to evaluate the effect of temperature on the cone tip resistance. Design concepts include the cone configuration, sensor installation and the temperature compensation process. The test shows that the tip resistance measured by strain gauge is affected by the temperature change. The error of the tip resistance increases with an increase in temperature change, while the temperature effect on the tip resistance of FBG cone is effectively compensated by using FBG temperature transducer. Temperature compensated tip resistance of the strain gauge cone shows the good matched profile with FBG cone which performs real-time temperature compensation during penetration. This study demonstrates that the temperature compensation by using FBG sensor is an effective method to produce the more reliable cone tip resistance.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.5
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• pp.163-170
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• 2006

Recently, piezocone penetration test is frequently used in order to estimate the characteristics of soft ground with standard penetration test, generally used in the past. In this study, the correlation of standard penetration test, piezocone penetration test and driving resistance of vertical drain is analyzed in order to increase the confidence for determination of soft ground depth. As the results of each zone, the relation between standard penetration test and piezocone penetration test shows qc=(1.09~1.63)N at the soft ground, determined by 5/30 N value which is decided for soft ground criteria. And qc=(1.21~1.98)N was shown at the point of compressible layer, evaluated by the preconsolidation pressure. And driving resistance of vertical drain is $65{\sim}70kgf/cm^2$ which is equal to $10kgf/cm^2$ of cone penetration resistance.

• 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.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.269-281
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• 2010

The cone penetration test(CPT) has been increasingly used for in situ site characterization. However, the use of CPT is often limited due to specific site conditions depending on the cone size, geometry, and capacity of the CPT system used. In South Korea, it has generally been considered that the CPT could be satisfactorily performed only in soft soils. Louisiana State University/ Louisiana Transportation Research Center has implemented a field-rugged continuous intrusion miniature cone penetration test (CIMCPT) system since the 1990s. The miniature cone penetrometer of the CIMCPT system has a cross-sectional cone area of $2cm^2$ allowing finer soil profiles compared to the standard $10cm^2$. The reduced cross-sectional area also enables a system capacity reduction leading to cost saving and ease in maintenance. In addition, the continuous intrusion mechanism allows fast and economic site investigations. Samsung C&T Corporation has recently implemented a similar CIMCPT system. In this study, case studies on the field application of Samsung CIMCPT system for the last 2 years are presented to illustrate its performance investigation and its usefulness and limitation. Results of the case studies show that the CIMCPT system can be applied to soils with cone tip resistance($q_c$) values up to about 30MPa and allows a reliable and useful way to characterize soft soils. The results also show that the rod buckling limits the investigation depth by the system and the large contact pressure of the CIMCPT truck prevents the use of the system at sites with soft surface soils. According to the results of the case studies, the Samsung CIMCPT system has been being upgraded with a miniature cone with a longer rod, a crawler-type transportation system, a pre-boring system, and so on.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.628-635
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• 2008

A series of cone penetration tests in large calibration chamber were performed to investigate the effect of cementation level, relative density and vertical confining stress on cone resistance. From the experimental results, it was observed that the cone resistance is increased with increasing gypsum content, relative density, and confining stress. The increasing ratio on cone resistance of cemented sand compared with that of uncemented sand, that is IR($q_c$), was increased with increasing gypsum content and relative density, whereas it was decreased as the vertical confining stress increases. It was also observed that the cementation of granular soil influences the behavior of ground at low level of confining stress and its effect is diminished with depth.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.02a
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• pp.59-70
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• 2000

본 연구에서는 콘관입속도가 콘관입시험 결과에 미치는 영향을 연구하기 위하여 LSU/CALCHAS(Louisiana State University Calibration Chamber System)를 이용한 미니 Piezocone의 관입시험이 수행되었으며 그 결과를 비교 분석하였다. 10회의 미니 Piezocone 관입시험이 Ko 조건에서 수행되었으며 33% kaolin, 67% sand mixture가 시료로 사용되었고, 콘관입속도 0.3, 0.6cm/sec, U1(filter element at the cone tip), U2(filter element above the cone base), OCR=1, 10 의 조건이 다양하게 적용되었다. 시험결과 Cone Resistance, Excess Pore Water Pressure, Sleeve Friction 은 U1, U2 두 종류의 콘에 대해서 모두 관입속도가 커짐에 따라 증가하였으나 OCR의 증가에 따라서는 감소하였으며 U1의 Excess Pore Water Pressure가 U2 경우보다 크게 측정되었다.

• Journal of the Korean Geotechnical Society
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• v.22 no.10
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• pp.55-67
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• 2006

Modern methods for designing IGM(Intermediate Geomaterial) socketed drilled shafts require knowledge of the compressive strength and modulus of the IGM. However, the weathered IGMs at many sites prohibit the recovery of samples of sufficient length and integrity to test cores in either unconfined or triaxial compression tests. Since rational design procedures usually require values of compressive strength, surrogate methods must be employed to estimate the compressive strength of the IGM. A surrogate method considered in this study was Texas cone penetrometer tests which were performed at several sites in North Central Texas. Correlations of Texas cone penetrometer tests and compressive strengths of cores from these formations are provided in the paper. In order to develop the relationships between Texas cone penetrations and side and base resistance of IGM socketed drilled shafts, three filed load tests were conducted in the same sites. Based on the field study and literature reviews, a design method for IGM socketed drilled shafts using Texas cone penetration test was proposed.

• Journal of the Korean Geotechnical Society
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• v.24 no.2
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• pp.77-86
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• 2008

The disturbance zone and measured values are affected by the size of the penetrometer. The local value may be measured by the smaller penetrometer. An ultra small Micro-Cone penetrometer (5mm in outer diameter) is designed and manufactured to characterize soil properties with minimum disturbance during penetration tests. The tip resistance is measured by using stain gauges attached near the Micro-Cone. In addition, the friction sleeve is adopted to effectively remove the skin friction from the tip resistance. Design concern includes the installation of stain gauges, circuits, penetration systems, penetration rate, sampling rate, operating temperature, and calibration. Application tests show that the clay interface, and the soil layers consisting of clay and sand are clearly detected by the Micro-Cone. Furthermore, the cone tip resistances measured by the Micro-Cone and the miniature cone (16mm in outer diameter) are similar. Note the resolution is much higher in the Micro-Cone. This study shows that the Micro-Cone may effectively detect the soil interface with high resolution, and with minimum disturbance.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.341-348
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• 2009

Various types of micro cone penetrometers have been developed by using strain gages for the layered soil detection. Strain gages, however, are affected by several factors such as temperature, self heating and lead wire length. In this study, micro cone penetrometers with 3~7mm in diameter, are developed by using FBG sensor to overcome the defects of the strain gage, and compensate the effect of temperature during penetration. In order to verifiy the accuracy and reliability of the developed FBG cone, the cone penetration test is performed on the layered soil. The tip resistance of FBG snesor shows excellent sensitivity, and can detect the interface of the layered soils with higher resolution. In addition, the 3mm micro cone penetrometer which is impossible cone diameter by using strain gages presents much higher sensitivity than the 7mm cone penetrometer. This study suggests that FBG sensor is a useful sensor for manufaturing the ultra small sized cone, and effectively detects the interface of the layered soil.