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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 25, Issue 12 - Dec 2009
Volume 25, Issue 11 - Nov 2009
Volume 25, Issue 10 - Oct 2009
Volume 25, Issue 9 - Sep 2009
Volume 25, Issue 8 - Aug 2009
Volume 25, Issue 7 - Jul 2009
Volume 25, Issue 6 - Jun 2009
Volume 25, Issue 5 - May 2009
Volume 25, Issue 4 - Apr 2009
Volume 25, Issue 2 - Feb 2009
Volume 25, Issue 1 - Jan 2009
Selecting the target year
Rock Bolt Integrity Assessment in Time-Frequency Domain : In-situ Application at Hard Rock Site
Lee, In-Mo ; Han, Shin-In ; Min, Bok-Ki ; Lee, Jong-Sub ;
Journal of the Korean Geotechnical Society, volume 25, issue 12, 2009, Pages 5~12
As rock bolts become one of the main support systems in tunnels and underground structures, the integrity of the rock bolts affects the safety of these structures. The purpose of this study is the evaluation of rock bolt integrity using wavelet transforms of the guided ultrasonic waves by using transmission test in the field. After several rock bolts with various defect ratios are embedded into a large scale concrete block and rock mass, guided waves are generated by a piezo disk element and measured by an acoustic emission (AE) sensor. The captured signals are analyzed in the time-frequency domain using the wavelet transform based on a Gabor wavelet. Peak values in the time-frequency domain represent the interval of travel time of each echo. The energy velocities of the guided waves increase with an increase in the defect ratio. The suitable curing time for the evergy velocity analysis is proposed by the laboratory test, and in-situ tests are performed in two tunnelling sites to verify the applicability of rock bolt integrity tests performed after proposed curing time. This study proves that time-frequency domain analysis is an effective tool for the evaluation of the rock bolt integrity.
Probabilistic Stability Analysis of Slopes by the Limit Equilibrium Method Considering Spatial Variability of Soil Property
Cho, Sung-Eun ; Park, Hyung-Choon ;
Journal of the Korean Geotechnical Society, volume 25, issue 12, 2009, Pages 13~25
In this paper, a numerical procedure of probabilistic slope stability analysis that considers the spatial variability of soil properties is presented. The procedure extends the deterministic analysis based on the limit equilibrium method of slices to a probabilistic approach that accounts for the uncertainties and spatial variation of the soil parameters. Making no a priori assumptions about the critical failure surface like the Random Finite Element Method (RFEM), the approach saves the amount of solution time required to perform the analysis. Two-dimensional random fields are generated based on a Karhunen-Lo
ve expansion in a fashion consistent with a specified marginal distribution function and an autocorrelation function. A Monte Carlo simulation is then used to determine the statistical response based on the random fields. A series of analyses were performed to verify the application potential of the proposed method and to study the effects of uncertainty caused by the spatial heterogeneity on the stability of slope. The results show that the proposed method can efficiently consider the various failure mechanisms caused by the spatial variability of soil property in the probabilistic slope stability assessment.
A Study on Correlation Analysis between Inventory Data and Danger Grade of Cut Slopes: Cut Slopes in Kangwondo and Chungcheongdo.
Kim, Jin-Hwan ; Lee, Jeong-Yeob ; Kim, Seung-Hyun ; Koo, Ho-Bon ;
Journal of the Korean Geotechnical Society, volume 25, issue 12, 2009, Pages 27~35
KICT (Korea Institute of Construction and Technology) and KISTEC (Korea Infrastructure Safety and Technology Corporation) have been carrying out inventory survey on cut slopes along national roads since 2006. Unlike precision safety check, cut slope inventory survey is a simple check about cut slope's characteristics with the naked eye to collect the data base of slope maintenance. Inventory survey is classified into general status, cut slope characteristics and inspector opinions. The inventory data are analyzed to identify dangerous slopes and decide a safety ranking. In this paper, we performed a correlation analysis using SPSS (ver.15) about the 10,461 cut slope inventory data which are collected in Kangwondo and Chungcheongdo from 2006 to 2008. We calculated the correlation coefficient between cut slope inventory data and the danger score derived from the data. And we evaluated cut slope inventory data which have the more influence on the danger degree of cut slope. According to results of correlation analysis, we found that inventory data influencing cut slope danger degree are stuck and fallen rock, orientation of discontinuity and angle of upper slope. And these data are slightly different by regionally. Later on, if inventory research is finished, we will understand regional characteristics of cut slopes.
Acceleration Effect of Self-Weight Consolidation of Dredged and Reclaimed Ground with PBD
Lee, Bum-Jun ; Park, Min-Chul ; Jeon, Je-Sung ; Lee, Song ;
Journal of the Korean Geotechnical Society, volume 25, issue 12, 2009, Pages 37~45
Dredging and reclamation which have been conducted steadily for creation of new coastal area have the demerit of taking a long time. Hence, a lot of researches on acceleration of self-weight consolidation have been proceeding continuously. In this paper, 30 cases of laboratory self-weight consolidation tests were conducted to understand the application of PDF method, one of the self-weight consolidation acceleration methods, to domestic dredged soils. Acceleration effect of self-weight consolidation was confirmed through comparison and analysis of completion times and settlements of self-weight consolidation for none installed case and 4 kinds of common used PBD installed cases. As a result of the tests, installation of PBD before filling is effective for time reduction of self-weight consolidation.
Modification of Bouwer and Rice Method to Evaluate Hydraulic Conductivity of Cutoff Wall Considering Filter Cake Development
Nguyen, The-Bao ; Lee, Chul-Ho ; Kwak, Tae-Hoon ; Choi, Hang-Seok ;
Journal of the Korean Geotechnical Society, volume 25, issue 12, 2009, Pages 47~55
As a conventional line-fitting method, the Bouwer and Rice method has been popularly adopted to estimate the hydraulic conductivity of an aquifer through a slug test. Because a vertical cutoff wall is usually very compressible and features a small wall thickness, the Bouwer and Rice method should be carefully applied to analyzing slug test results to estimate the hydraulic conductivity of vertical cutoff walls. In addition, a relatively impermeable layer, called a filter cake, formed at the interface between the cutoff wall and the natural soil formation makes it difficult to use the Bouwer and Rice method directly. In order to overcome such limitations, the original Bouwer and Rice method has been modified by incorporating the concept of the flow net method. In this modification, the geometry condition of cutoff walls including the filter cake is effectively considered in evaluating the hydraulic conductivity of a vertical cutoff wall.
Characteristics of Deformation and Shear Strength of Parallel Grading Coarse-grained Materials Using Large Triaxial Test Equipment
Jin, Guang-Ri ; Snin, Dong-Hoon ; Im, Eun-Sang ; Kim, Ki-Young ;
Journal of the Korean Geotechnical Society, volume 25, issue 12, 2009, Pages 57~67
Along with the advanced construction technologies, the maximum size of coarse aggregate used for dam construction ranges from several cm to 1m. Testing the original gradation samples is not only expensive but also causes many technical difficulties. Generally, indoor tests are performed on the samples with the parallel grading method after which the results are applied to the design and interpretation of the actual geotechnical structure. In order to anticipate the exact behavior characteristics for the geotechnical structure, it is necessary to understand the changes in the shear behavior. In this study, the Large Triaxial Test was performed on the parallel grading method samples that were restructured with river bed sand-gravel, with a different maximum size, which is the material that was used to construct Dam B in Korea. And the Stress - Strain characteristics of the parallel grading method samples and the characteristics of the shear strength were compared and analyzed. In the test results, the coarse-grained showed strain softening and expansion behavior of the volume, which became more obvious as the maximum size increased. The internal angle of friction and the shear strength appeared to increase as the maximum size of the parallel grading method sample increased.
Estimation of Dynamic Material Properties for Fill Dam : I. In-situ Shearwave Velocity Profiles
Kim, Jong-Tae ; Kim, Dong-Soo ; Park, Heon-Joon ; Kwon, Hyek-Kee ;
Journal of the Korean Geotechnical Society, volume 25, issue 12, 2009, Pages 69~85
It is very important to measure reliable dynamic properties of each zone in dam for seismic design. However, the Vs values of core and rock-fill zone are seldom determined by field test. Consequently, seismic design in dam is performed using Vs values assumed or empirically determined. So, it is required that reliable Vs has to be evaluated by in-situ test. In this study, surface wave method, which is nondestructive, was applied to dam to evaluate Vs profiles of core and rock-fill zone in dam. In 6 dams, using SASW and HWAW methods, Vs profiles were evaluated reliably. D/B of Vs profiles of each zone with depth and relationship between confining pressure and Vs profiles of rock-fill zone were constructed including existing results of other dams. The evaluated D/B and proposed relationship were compared with the frequently used empirical method by Sawada and Takahashi.
Estimation of Dynamic Material Properties for Fill Dam : II. Nonlinear Deformation Characteristics
Lee, Sei-Hyun ; Kim, Dong-Soo ; Choo, Yun-Wook ; Choo, Hyek-Kee ;
Journal of the Korean Geotechnical Society, volume 25, issue 12, 2009, Pages 87~105
Nonlinear dynamic deformation characteristics, expressed in terms of normalized shear modulus reduction curve (G/
curve) and damping curve (D-
), are important input parameters with shear wave velocity profile (
-profile) in the seismic analysis of (new or existing) fill dam. In this paper, the reasonable and economical methods to evaluate the nonlinear dynamic deformation characteristics for core zone and rockfill zone respectively are presented. For the core zone, 111 G/
curves and 98 damping curves which meet the requirements of core material were compiled and representative curves and ranges were proposed for the three ranges of confining pressure (0~100 kPa, 100 kPa~200 kPa, more than 200 kPa). The reliability of the proposed curves for the core zone were verified by comparing with the resonant column test results of two kinds of core materials. For the rockfill zone, 135 G/
curves and 65 damping curves were compiled from the test results of gravelly materials using large scale testing equipments. The representative curves and ranges for G/
were proposed for the three ranges of confining pressure (0~50 kPa, 50 kPa~100 kPa, more than 100 kPa) and those for damping were proposed independently of confining pressure. The reliability of the proposed curves for the rockfill zone were verified by comparing with the large scale triaxial test results of rockfill materials in the B-dam which is being constructed.
Applicability of CPT-based Toe Bearing Capacity of PHC Driven Piles
Le, Chi Hung ; Chung, Sung-Gyo ; Kim, Sung-Ryul ;
Journal of the Korean Geotechnical Society, volume 25, issue 12, 2009, Pages 107~118
As CPT penetration tends to show a similar behavior to that of pile driving, a number of methods for estimating the toe bearing capacity of piles based on CPT data have been proposed. To evaluate the applicability of the methods in this country, a total of 172 dynamic load tests data on PHC piles and 82 CPT data at a site in the Nakdong River estuary were collected. A specific four-step procedure was adopted for the selection of the reliable data, and statistical techniques were then applied to the analysis of the applicability. The results indicated that among a total of 10 CPT-based methods applied, the best one is the Aoki method (1975), followed by the LCPC (1982), ICP (2005) methods and others.
An Optimal Digital Image Analysis Technique for Measuring Deformation of Granular Soils
Jang, Eui-Ryong ; Jung, Young-Hoon ; Chung, Choong-Ki ;
Journal of the Korean Geotechnical Society, volume 25, issue 12, 2009, Pages 119~130
To measure the soil deformation, two common techniques of the digital image analysis-Particle Image Velocimetry (PIV) and Digital Image Correlation (DIC)-have been used. To generally apply these techniques to the soils, the accuracy of these techniques should be evaluated under various conditions. In this study, the influence factors including the image resolution, the degree of displacement and deformation, the size of pixel subsets, and analysis techniques were analyzed. The deformation of an idealized particle assembly using the discrete element method was measured by the digital image analyses, and then the results were compared with the actual deformations. To conduct the optimal digital image analysis, various factors are systematically analyzed in terms of the degree of the displacement and the deformation.
Numerical Investigation on Behavior of Back-to-Back Reinforced Earth Wall
Yoo, Chung-Sik ; Kim, Jae-Wang ;
Journal of the Korean Geotechnical Society, volume 25, issue 12, 2009, Pages 131~142
Geosynthetic reinforced soil walls are well recognized alternatives to conventional retaining walls due to many advantages in terms of ease of construction, economy, and aesthetics, among others. In recent years, the use of back-to-back (BTB) geosynthetic reinforced soil walls has been increasing for roadway and railway construction. However, there are insufficient studies concerning the behavior of BTB type geosynthetic reinforced soil walls. In this study a series of finite element analysis were performed for BTB walls with various wall geometry and reinforcement distribution. The results were then analyzed to relate the wall geometry and reinforcement distribution and the performance of BTB walls. Optimum reinforcement pattern was also investigated.