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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Geotechnical Society
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Journal DOI :
Korean Geotechical Society
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Volume & Issues
Volume 26, Issue 12 - Dec 2010
Volume 26, Issue 11 - Nov 2010
Volume 26, Issue 10 - Oct 2010
Volume 26, Issue 9 - Sep 2010
Volume 26, Issue 8 - Aug 2010
Volume 26, Issue 7 - Jul 2010
Volume 26, Issue 6 - Jun 2010
Volume 26, Issue 5 - May 2010
Volume 26, Issue 4 - Apr 2010
Volume 26, Issue 3 - Mar 2010
Volume 26, Issue 2 - Feb 2010
Volume 26, Issue 1 - Jan 2010
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The Effect of Pressurized Grouting on Pullout Resistance and the Group Effect of Compression Ground Anchor
Kim, Tae-Seob ; Sim, Bo-Kyoung ; Lee, Kou-Sang ; Lee, In-Mo ;
Journal of the Korean Geotechnical Society, volume 26, issue 6, 2010, Pages 5~19
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.
The Unsaturated Stress Strain Behavior of CDG (Completely Decomposed Granite) Soils
Ham, Tae-Gew ; Ahn, Tae-Bong ;
Journal of the Korean Geotechnical Society, volume 26, issue 6, 2010, Pages 21~28
Decomposed granite soil is the most common type of soils. The measurement of the stress-strain-strength behavior of anisotropic decomposed granite soils is very important for the deformation and stability analysis of slopes, retaining walls, excavations. A series of unsaturated-drained triaxial compression tests were performed to know unsaturated strength properties. The sample had three different angles of the axial (major principal) direction to the sedimentation plane (compaction plane): 0, 45 and 90 degrees. The compression strain of specimens subjected to an isotropic compression was strongly influenced by the sedimentation angle. In addition, the time dependence was independent of the sedimentation angle in relation to the deformation behavior during the secondary compression process. The effect of the sedimentation angle on the triaxial compression strength and deformation was clearly shown with low confining stress. The effect of the sedimentation angle on the compressive strength and deformation was more evident in saturated specimens. A new method of predicting the shear strength of unsaturated decomposed granite soils, considering compaction angles, was proposed.
The Effects of the Breadth of Foundation and Rock Layer on the Installation Method of Micro-piles
Hwang, Tae-Hyun ; Kim, Ji-Ho ; Kwon, Oh-Yeob ;
Journal of the Korean Geotechnical Society, volume 26, issue 6, 2010, Pages 29~38
Micro-piles have been used to increase the bearing capacity or to restrain settlement of existing shallow foundation. Recently, micro-piles are used to support the shallow foundation, to stabilize the slope and to resist the sliding of retaining wall. Using the micro-piles in geotechnical engineering, some investigators have studied the effective installing method by model test or field test. But most of previous studies are chiefly focused on the micro-piles in sand or clay layer. If a rock layer exists in soil, the installing length of micro-piles may be determined by the depth of rock layer. In this case, the stiffness of pile may be changed by the installing length of pile, and so the installing method has to be altered by the changed stiffness of pile. Model tests have been conducted to study the installation method of micro-pile in soil with rock layer. As a result, when the ratio of length of pile is below 50 (
), installing of micro-piles in vertical position is effective regardless of the depth of rock layer. If the depth of rock layer is deeper than soil failure zone and the ratio of the length of pile exceeds 50 (L/d>50), installing of the micro-piles in sloped position is effective.
Structural Analysis of CBS (Composite Basement Wall System)-RIB Underground Structures Using Numerical Modeling
Yoo, Han-Kyu ; Kim, Yeon-Sung ;
Journal of the Korean Geotechnical Society, volume 26, issue 6, 2010, Pages 39~44
In case of the design method, which is used in the inside and outside of the country, on corrugated multi plate structures, section modulus would be determined by assuming 2-dementioanl equivalent section of those structures. However, it is impossible to consider 3-dimentional effects when 2-dimentional design method is applied since structures are reinforced with a pattern of the 1200, 1600 mm reinforcements except the 800 mm reinforcement. Thus, in this study, technical specification standard is analyzed for the existing corrugated multi plate design methods, and section strengths, moments, and so on of equivalent and practical sections are compared and estimated using 3-dimentional FEM (finite element method) for semicircles and architectural features widely used. Based on the results of that analysis, analytical basis for 3-dimentional design of the CBS-RIB is suggested.
Numerical Investigation on the Behavior of Braced Excavation Supported by Steel Pipe Struts
Yoo, Chung-Sik ; Na, Seung-Min ; Lee, Jong-Goo ; Jang, Dong-Wook ;
Journal of the Korean Geotechnical Society, volume 26, issue 6, 2010, Pages 45~56
This paper presents the results of a numerical investigation on the behavior of deep excavation wall system supported by steel pipe struts. A series of three-dimensional finite element analyses were carried out on a braced excavation case which adopted steel pipe struts. The results indicated that the mechanical behavior of the steel pipe supported braced excavation is comparable to that of a conventional H-pile supported excavation, although the steel pipe supported system allows a larger longitudinal spacing than the conventional H-pile strut system. Also shown is that the sectional stresses of the steel pipe support system are within the allowable values. This implies that the steel pipe support system can be effectively used as an alternative to conventional H-pile support system.
Seismic Analysis of Tunnel in Transverse Direction Part I: Estimation of Seismic Tunnel Response via Method of Seismic Displacement
Park, Du-Hee ; Shin, Jong-Ho ; Yun, Se-Ung ;
Journal of the Korean Geotechnical Society, volume 26, issue 6, 2010, Pages 57~70
Recent earthquakes have demonstrated that the tunnels, which were once considered to be highly resistant to earthquakes, are susceptible to substantial damage under severe seismic loading. Among various modes of deformation under an earthquake loading, the response of the tunnel in the transverse direction is known to be the critical mode. This paper investigates the seismic response of the tunnel in the transverse direction using the method of seismic displacement, which is a type of pseudo-static analysis. Firstly, the methods of calculating the ground deformation are compared. It is shown that the single and double cosine may not provide an accurate estimation of the ground deformation, and that a one-dimensional site response analysis needs to be performed for a more reliable evaluation. Secondly, the tunnel responses are calculated using the simplified, analytical, and numerical solutions. It is demonstrated that the simplified method provides poor estimates of the tunnel response ground deformation. The analytical solution is shown to be effective in modeling circular tunnels in uniform ground, but has serious limitation in modeling tunnel response in non-uniform ground. Numerical analyses are shown to be applicable to all cases, and give the most accurate estimates of the tunnel response. It is also demonstrated that the linear solutions can be so conservative that the soil nonlinearity needs to be accounted for more accurate evaluation of the tunnel response.
Seismic Analysis of Tunnel in Transverse Direction Part II: Evaluation of Seismic Tunnel Response via Dynamic Analysis
Park, Du-Hee ; Shin, Jong-Ho ; Yun, Se-Ung ;
Journal of the Korean Geotechnical Society, volume 26, issue 6, 2010, Pages 71~85
Dynamic analyses of tunnels are widely performed in practice in Korea. Accurate performance of a dynamic analysis is very difficult, requiring appropriate application of lower and lateral boundary conditions, deconvolution, constitutive model, and selection of dynamic soil properties etc. Lack of a systematic guideline on how to perform the dynamic analysis makes it even more difficult to perform an analysis. In addition, dynamic analyses are not needed in most cases and pseudo-static analyses are more than adequate. However, they are performed without a clear understanding on the need for the dynamic analysis and differences between the two methods. In this study, firstly, a guideline for correctly performing a 2D dynamic analysis is developed. Secondly, the differences in the tunnel responses using dynamic and pseudo-static analyses are discussed and compared. The results show that the discrepancies between the dynamic and static analyses are not significant for most cases. It is therefore recommended that the dynamic analyses be performed at tunnel portal, very soft ground, or in cases where spatial variation of the ground motion needs to be considered in the seismic analysis of tunnels in transverse direction.