• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1175-1182
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• 2005

Using KUCCS, which enables real-time monitoring and controlling, the various boundary condition and in-situ field stress condition was simulated, to derive the correlation among ${{\sigma}_v}'-Dr-N$in domestic sandy soils. Soil specimens, having various relative density and confined stress, were formulated to evaluate N-value from the SPT. and Pile Driving Analyzer, PDA, was employed as a measuring device for the energy transfer efficiency in the rod. From the quantitative analysis of N-value, the correlating equation, $N_{60}/{D_r}^2=16.35+14.45{{\sigma}_v}'$ was obtained on the basis of Skempton's method(1986). More reliable soil parameters can be obtained from the N-value by using this study which considered regional characters and the correlation among ${{\sigma}_v}'-Dr-N$.

• Geomechanics and Engineering
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• v.28 no.6
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• pp.625-636
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• 2022

The standard penetration test (SPT) obtaining the N value of the number of blows has been widely used in various subsurface conditions, including in weathered soil and rock on fresh bedrock, in geotechnical studies pertaining to the design of foundations and earth structures. This study examined the applicability of SPTs terminated conventionally after 50 blows for a penetration of less than 30 cm, particularly in weathered strata, at four sites in Korea. The N values obtained during practical SPTs are typically extrapolated linearly at 30 cm penetration, despite the possibility of a nonlinear relationship between blow counts and penetration. Such nonlinearity in weathered strata has been verified by performing special SPTs ensuring 30 cm penetration. To quantify the nonlinearity in dense strata, we conducted statistical regression analyses comparing the differences (DN) between the N values measured by the special SPTs and those extrapolated using the practical approach with the differences (DP) between the 30 cm penetration and the penetration during 50 blows. Bi-linear relationship models between DN and DP were subsequently proposed for determining the N values at 30 cm penetration in weathered strata. The N values reflecting nonlinearity could be determined from the linearly extrapolated N values by adding a modeled DN value.

• Journal of the Korean Geotechnical Society
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• v.20 no.9
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• pp.17-23
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• 2004

Strength and deformation characteristics of oyster shell-sand mixtures were investigated to utilize waste oyster shell being treated as a waste material. Standard penetration test (SPT) is a common method to obtain in-situ strength in sand. However, in case of oyster shell-sand mixtures, there was no information between SPT N-value and internal friction angle of mixture soils. In this paper SPT experiments from several large scaled model chamber tests and large scaled direct shear tests were carried out with varying unit weight of oyster shell-sand mixtures. Appropriate correlations were in tile study observed among N-value, unit weight and internal friction angle, which make it possible to estimate in-situ strength from SPT and the coefficient of volume compressibility from the confined compression tests to compute the settlement of oyster shell-sand mixtures.

• Journal of the Korean Geotechnical Society
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• v.26 no.6
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• pp.5-19
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• 2010

The purpose of this study is to figure out the effect of pressurized grouting on the pullout resistance and the group effect of the compression ground anchor by performing pilot-scale chamber tests and field tests. The laboratory tests are carried out for 3-types of soils which are abundant in the Korean peninsular. Experimental results showed that the enlargement of anchor diameters estimated from the cavity expansion theory matches reasonable well with that obtained from experiments. Moreover, the required injection time as a function of the coefficient of permeability of each soil type was proposed. A series of in-situ anchor pullout tests were also performed to experimentally figure out the effect of pressurized grouting on the pullout resistance. Experimental results also showed that the effect of the pressurized grouting is more prominent in a softer ground with smaller SPT-N value in all of the following three aspects: increase in anchor diameter; pullout resistance; and surface roughness. The pressurized grouting effect in comparison with gravitational grouting was found to be almost nil if the SPT-N value is more than 50. Based on experimental results, a new equation to estimate the pullout resistance as a function of the SPT-N value was proposed. And based on in-situ group anchor pullout tests results, a new group effect equation was proposed which might be applicable to decomposed residual soils which are abundant in the Korean peninsular.

• Journal of the Korean GEO-environmental Society
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• v.5 no.3
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• pp.61-70
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• 2004

N-value by the SPT is one of the key parameter for settlement evaluation. However, if the ground is firm, the usual N-value is not blow count of 30cm depth penetration. In such case, if N-value is more than 50 with 30cm penetration, the N-value 50 is applied for settlement analysis. Therefore, in this study, the modified method of N-value estimation is suggested and compared the settlement by Elastic Theory, and the measured field data by Plate Load Test. As the result of this study, it is shown that the settlement by Elastic Theory with the modified N-value is more accurate than settlement by usual N-value. The application of Elastic Theory for pure sand is also evaluated in this paper.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.1168-1176
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• 2010

Currently drilling investigation and the SPT in parallel not only organization and peculation sincerity quality historian of test to be old the data was abundant with the site ground investigation test which is representative and the research of empirical formula in compliance with many scholar was accomplished and was come. The data which is like this wide is used with geotechnical engineering data of plan and space-time of the field which is various. SPT with tentative voluntary skillful degree record method of variety and technical expert of equipment, according to site conditional is consistent the quality of ground condition but cannot be made to show there is a tendency and specially the point whose is difficult actually accurately to follow the interval which decides in quality as a matter of tentative standard of drill and the test in parallel and a tentative method exists. From the research which sees consequently also the skill of variety and technical expert of equipment of SPT, strong point of the SPT automation logger will be able to complement the problem point of quality etc. of site condition under comparison analyzing should have been boiled about SPT of existing and tentative methods and N-value.

• Geotechnical Engineering
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• v.8 no.1
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• pp.59-66
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• 1992

The SPT If value has been known to be influenced by various factors, among which the actually delivered energy level of the falling ram has the most significant effect. If N values of different energy levels are to be applied in the general analysis which is based on N values of standard energy levee the safety of the foundation might be in danger or the design might be overestimated. In this study the actual falling velocity of the ram has been measured so that the energy level could be estimated. The results Indicated that the energy level should be considered in the analysis or the design in this country, since the measured values are different from the internationally accepted scandard value, N60

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1340-1352
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• 2008

In this study, S-wave velocity range is gauged in every field test method at the total 5 locations in the marine deposits in Incheon area. field test method is accomplished the SPT(Standard Penetration Test), CPT(Cone Penetration Test), SPS(Suspension PS Logger), SCPT (Seismic Cone Penetration Test) and so on. The S-wave velocity of SCPT in the downhole test method is measured lower than SPS logger at the N value > 15 range. But at the N value < 15 range, SPS logger and SCPT result is measured same. In this result, although the soil strength of the downhole test method increased, the rate of S-wave velocity is tend to be slowed. This result shows that the downhole test is difficult to apply at the place that the intensity of soil is more extreme and harder soil. And it shows that the existing Imai(1982) type that is mostly used within the country is not suitable for the marine deposits. Thus, the empirical formula that can show the range of S-wave velocity in each N value for domestic soil is needed.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.09a
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• pp.93-116
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• 2005

SPT-Uphole tomography method was introducedand verified in this paper. In SPT-Uphole method, SPT (Standard Penetration Test) which is common in site investigation, was used as a source and several surface geophones in line were used as receivers. Shear wave velocity (Vs) distribution map which has triangular shape around the boring point can be obtained by tomography inversion. The factors for obtaining reliable result of SPT-Uphole tomography are exact travel time information and accurate inversion method. To establish of the SPT-Uphole tomography procedure, the most reliable method for obtaining exact travel time information and verification of tomography inversion method were studied by using theoretical travel time information and finite element method (FEM) analysis. finally, SPT-Uphole tomography method was performed at the weathered soil site in Kimje. By comparing with several boring data including SPT-N value, feasibility of this method was verified in the field.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2C
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• pp.109-120
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• 2006

SPT-Uphole test is a seismic field test using receivers on ground surface and a SPT (Standard penetration test) source in depth. Even though this method is simple and economic, it makes hesitate to apply in real field that it is difficult to obtain reliable travel time information of shear wave because of the characteristics of SPT impact source. To overcome this shortcoming, in this paper, modified SPT-Uphole method using two component surface geophones was suggested. Numerical analysis was performed using finite element method for understanding the characteristics of surface motion induced by in-depth vertical source, and comparison study of the various methods which determine the travel time information in SPT-Uphole method was performed. In result, it is thought that the most reasonable method is using the first local maximum point of the root mean square value signals of vertical and horizontal component in time domain. Finally, modified SPT-Uphole method using two component surface geophones was performed at the site, and the applicability in field was verified by comparing wave velocity profiles determined by the SPT-Uphole method with the profiles determined by SASW method and SPT-N values.