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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Geotechnical Society
Journal Basic Information
Journal DOI :
Korean Geotechical Society
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Volume & Issues
Volume 21, Issue 10 - Dec 2005
Volume 21, Issue 9 - Nov 2005
Volume 21, Issue 8 - Oct 2005
Volume 21, Issue 7 - Sep 2005
Volume 21, Issue 6 - Aug 2005
Volume 21, Issue 5 - Jul 2005
Volume 21, Issue 4 - Jun 2005
Volume 21, Issue 3 - Apr 2005
Volume 21, Issue 2 - Mar 2005
Volume 21, Issue 1 - Feb 2005
Selecting the target year
Influence of Progressive Consolidation on Consolidation Behavior of Normally Consolidated Clayey Soil with Vertical Drains
Yune Chan-Young ; Chung Choong-Ki ;
Journal of the Korean Geotechnical Society, volume 21, issue 6, 2005, Pages 5~18
In this study, the influence of progressive consolidation from the drainage boundary on the subsequent process of consolidation was investigated. Analytical theory and numerical program f3r consolidation of clayey soil were developed based on finite difference method, in which spatial variation of permeability and volume compressibility were implemented. And model ground with normally consolidated clayey soils and a vertical drain at its center were simulated. Various types of soils with different relations between coefficient of volume compressibility and permeability and void ratio were applied. Also numerical simulations based on the properties of the normally consolidated clay at Nakdong River basin and reconstituted kaolinite soil were performed to recognize its practical impact. Consequently, it is found out that retardation of consolidation induced by progressive consolidation is very important to understand consolidation behavior on field conditions and its effect is remarkable at the initial state of consolidation, and increases with plasticity index and applied load.
Nonlinear Three-dimensional Analysis of Piled Piers Considering Coupled Cap Rigidities
Won Jin-Oh ; Jeong Sang-Seom ;
Journal of the Korean Geotechnical Society, volume 21, issue 6, 2005, Pages 19~30
A coupled three-dimensional pile group analysis method was developed by considering complex behavior of sub-structures (pile-soil-cap) which included soil nonlinearity and the behavior of super-structure (pier). As an intermediate analysis method between FBPier 3.0 and Group 0.0, it took advantages of each method. Among the components of a pile group, individual piles were modeled with stiffness matrices of pile heads and soils with nonlinear load-transfer curves (t-z, q-z and p-y curves). A pile cap was modeled with modified four-node flat shell elements and a pier with three-dimensional beam element, so that a unified analysis could be possible. A nonlinear analysis method was proposed in this study with a mixed incremental and iteration techniques. The proposed method for a pile group subjected to axial and lateral loads was compared with othe. analytical methods (i.e., Group 6.0 and FBPier 3.0). It was found that the proposed method could predict the complex behavior of a pile group well, even though piles were modelled simply in this study by using pile head stiffness matrices which were different from the method introduced in FBPier 3.0
A Study for on Application of Bamboo Soil Nailing System
Bang Yoon-Kyung ; Kim Hong-Taek ; Yoo Si-Dong ; Yoo Chan-Ho ;
Journal of the Korean Geotechnical Society, volume 21, issue 6, 2005, Pages 31~40
In this study, a newly modified soil nailing technology which uses bamboo, rich natural material growing in southern areas, is developed to prevent the soil pollution and to overcome the difficulty of excavation near existing structures. Experimental and analytical studies were performed to confirm application possibility of bamboo taking the place of existent reinforcement material, that is steelbar, FRP and etc. In experimental study, strength characteristics of bamboo material were analyzed, and pull-out resistance of bamboo soil nailing system by field pull-out tests was examined. In analytical study, limit equilibrium analysis and displacement analysis were performed, and application possibility of bamboo soil nailing system was analyzed. As the result of this study, bamboo has comparatively good strength and pull-out resistance characteristics. It is expected that bamboo can be used as satisfactory reinforcement material by selecting bamboo with reguired diameter and by controlling the number of bamboo strips. Bamboo is an alternative for the reinforcement of soil nailing system, especially temporary support system in excavation near the existing structures.
Development of Backfill Materials for Underground Power Cables Considering Thermal Effect
Lee Dae-Soo ; Kim Dae-Hong ; Hong Sung-Yun ;
Journal of the Korean Geotechnical Society, volume 21, issue 6, 2005, Pages 41~52
Because the allowable current loading of buried electrical transmission cables is frequently limited by the maximum permissible temperature of the cable or of the surrounding ground, there is a need fur cable backfill materials that can maintain a low thermal resistivity even while subjected to high temperatures for prolonged periods. Temperatures greater than
may lead to breakdown of cable insulation and thermal runaway if the surrounding backfill material is unable to dissipate the heat as rapidly as it is generated. This paper describes the results of studies aimed at the development of backfill material to reduce the thermal resistivity. A large number of different additive materials were tested to determine their applicability as a substitute material. Tests were carried out for Dongrim river sand, a relatively uniform sand of very high thermal resistivity,
when dry, and Jinsan granite screenings, and D-2 (sand and granite screenings mixture), E-1 (rubble and granite screenings mixture), a well-graded materials with low thermal resistivity, about
when at 10 percent water content,
when dry. Based on this research, 3 types of backfill materials were suggested for improved materials with low thermal resistivity and the applicability was assessed through field tests.
Pre-stress Effect of Geosynthetics-reinforced Soil Structure
Kim Eun-Ra ; Kang Ho-Keun ;
Journal of the Korean Geotechnical Society, volume 21, issue 6, 2005, Pages 53~65
This paper presented a mechanism of the soil structure reinforced by geosynthetics, in which the reinforcing mechanism is treated as the effect arising from the reinforcement process to prevent the dilative deformation of soil under shearing. A full-scale in-situ model test was carried out by introducing the prestress method to enhance the geosynthetic-reinforcement, and the prestress effect through the FEM is also examined. The elasto-plastic model and the initial parameters needed in the FEM are presented. Moreover, the theoretical prediction is compared with the experimental results, which were obtained by a full-scale in-situ model test.
Evaluation of Field Nonlinear Modulus of Subgrnde Soils Using Repetitive Static Plate Bearing Load Test
Kim Dong-Soo ; Seo Won-Seok ; Kweon Gi-Chul ;
Journal of the Korean Geotechnical Society, volume 21, issue 6, 2005, Pages 67~79
The field plate load test has a good potential for determining modulus since it measures both plate pressure and settlement. Conventionally the modulus has been assumed to be a constant secant value defined from the settlement of the plate at a given load intensity. A constant modulus (modulus of subgrade reaction, k), however, may not be a representative value of subgrade soil under working load. Field strain(o. stress)-dependent modulus characteristics of subgrade soils, at relatively low to intermediate strains, are important in the pavement design. In this study, the field strain dependent moduli of subgrade soils were obtained using cyclic plate load test. Testing procedure and data reduction method are proposed. The field crosshole and laboratory resonant column tests were also performed to determine field nonlinear modulus at
strains, and the modulus values and nonlinear trends are compared to those obtained by cyclic plate load tests. Both modulus values match relatively well when the different state of stress between two tests was considered, and the applicability of field cyclic plate load test for determining nonlinear modulus values of subgrade soils is verified.
Behavior of Shear Strength of Coarse Grained Materials Based on Large Scale Direct Shear Test (I)
Lee Dae-Soo ; Kim Kyoung-Yul ; Hong Sung-Yun ; Jo Hwa-Kyung ; Whang Sung-Chun ;
Journal of the Korean Geotechnical Society, volume 21, issue 6, 2005, Pages 81~91
'Coarse grained material' refers to crushed stones or gravels, and the behaviour of soil containing coarse grained material is not easily defined using the conventional soil mechanics theory due to the influences of large particles, therefore large scale test is essential to investigate their effects. Previous studies have identified the major factors affecting the properties of coarse grained materials by using large scale shear testing apparatus, such as maximum particle size, water content, density and uniformity coefficients. In this paper, the effect of variation of maximum particle size and water content on shear strength was analyzed from the results of large scale shear test. In addition, the fiction coefficient at critical state per vertical load was estimated using the equation proposed by Wood (1998). The sample for the test was obtained from the local quarry sites. Tests results show that the shear strength for 50.8 m maximum particle size is relatively larger than that of 76.3 m and air-dry sample has larger shear strength than saturated sample. In the meantime, the friction coefficient at critical state shows
according to the test conditions.
Asymptotic Analysis for Hydraulic Fractures and Applicability of Boundary Collocation Method
Sim Young-Jong ; kim Hong-Ta다 ;
Journal of the Korean Geotechnical Society, volume 21, issue 6, 2005, Pages 93~100
The occurrence of multi-segmented hydraulic fractures that show different behavior from the single fracture is common phenomenon. However, it is not easy to evaluate the behavior of multiple fractures computed by most numerical techniques because of complicated process computation. This study presents how to efficiently calculate the displacement of the multi-segmented hydraulic fractures using the boundary collocation method (BCM). First of all, asymptotic solutions are obtained for the closely spaced overlapping fractures and are compared with those by the BCM where the number of collocation points is varied. As a result, the BCM provides an excellent agreement with the asymptotic solutions even when the number of collocation points is reduced ten times as many as that of conventional implementations. Accordingly, the numerical simulation of more realistic and, hence, more complex fracture geometries by the BCM would be valid with such a significant reduction of the number of collocation points.
A Proposition of Site Coefficients and Site Classification System for Design Ground Motions at Inland of the Korean Peninsula
Sun Chang-Guk ; Chung Choong-Ki ; Kim Dong-Soo ;
Journal of the Korean Geotechnical Society, volume 21, issue 6, 2005, Pages 101~115
For the site characterization at two inland areas, Gyeongju and Hongsung, which represent geomorphic and geologic characteristics of inland region in Korea, in-situ seismic tests containing borehole drilling investigations and resonant column tests were peformed and site-specific seismic response analyses were conducted using equivalent linear as well as nonlinear scheme. The soil deposits in Korea were shallower and stiffer than those in western US, from which the site coefficients and site classification system in Korea were derived. Most sites were categorized as site classes C and D based on the mean shear wave velocity
of the upper 30 m
, ranging between 250 and 650 m/s. According to the acceleration response spectra determined from the site response analyses, the site coefficients specified in the current Korean seismic design guide underestimate the ground motion in the short-period band and overestimate the ground motion in mid-period band. These differences can be explained by the differences in the bedrock depth and the soil stiffness profile between Korea and western US. The site coefficients,
for short-period and
for mid-period, were re-evaluated and the site classification system, in which sites C and D were subdivided according to
together with the existing
was introduced accounting for the local geologic conditions at inland region of the Korean peninsula. The proposed site classification system in this paper is still rudimentary and requires modification.
The Behaviour Characteristics of Strength and Deformation of the Deposited Soft Clay Owing to Contamination
Chun Byung-Sik ; Ha Kwang-Hyun ;
Journal of the Korean Geotechnical Society, volume 21, issue 6, 2005, Pages 117~126
The chemical property analysis on the deposited clay using scanning electron microscope and energy dispersive x-ray spectrometer were performed. Also, the triaxial compression tests and consolidation tests using NaCl aqueous solution and leachate as substitute pore (or saturated) water in samples were carried out to find out the behaviour characteristics of strength and deformation of contaminated deposited clay. from the chemical composition analysis results of clay samples, the magnitudes of composition ratio were revealed in the order of O, C, Si, Al, and Fe. Of these, why the ratio of carbon appeared to be large is estimated as due to the increase of the phyto-planktons after the construction of tide embankment. In the triaxial compression test and consolidation test results, the shear strength and compression properties have increased with the increase in concentration of contaminant (NaCl). This phenomenon is considered as to be caused by the changes of soil structure to flocculent structure owing to the decrease in the thickness of diffuse double layer in proportion to increase in the concentration of electrolyte.
Strain-rate-dependent Consolidation Characteristics of Busan Clay
Kim Yun-Tae ; Jo Sang-Chan ; Jo Gi-Young ;
Journal of the Korean Geotechnical Society, volume 21, issue 6, 2005, Pages 127~135
In order to analyze effects of strain rate on consolidation characteristics of Busan clay, a series of constant rate of strain (CRS) consolidation tests with different strain rate and incremental loading tests (ILT) were performed. From experimental test results on Busan clay, it was found that the preconsolidation pressure was dependent on the corresponding strain rate occurring during consolidation process. Also, consolidation curves normalized with respect to preconsolidation pressure gave a unique stress-strain curve. Coefficient of consolidation and permeability estimated from CRS test had a tendency to converge to a certain value at normally consolidated range regardless of strain rate. An increase in excess pore pressure was observed after the end of loading without change of total stress on the incremental loading test, which phenomenon is called Mandel-Cryer effect. It was also found that rapid generation of excess pore pressure took place due to collapse of soil structure as effective stress approached to preconsolidation pressure.
Adequacy Evaluation of Stability Analyses Considering Rainfall Infiltration on Railroad Cut-off Soil Slopes
Lee Su-Hyung ; Hwang Seon-Keun ; Sagong Myung ; Kim Hyun-Ki ;
Journal of the Korean Geotechnical Society, volume 21, issue 6, 2005, Pages 137~146
299 railroad slopes were investigated and the failure characteristics and reinforcement patterns were analyzed. Stability analyses on the 14 cut-off soil slopes were carried out. Surficial failures were predicted by infinite slope analyses assuming the temporarily perched ground water table at soil surface during rainfall period. Limit equilibrium analyses were also carried out and the influences of rainfall infiltration on the slope stabilities were taken Into account by seepage analyses using finite element method and by assuming ground water tables to be located adjacent to soil surface. The adequacy of those analyses was evaluated by comparing the slope failure characteristics between analysis results and the past failure records. From the comparison results, it was deduced that the limit equilibrium analyses were not appropriate to estimate the shallow failure that occurred at most of the railroad cut-off soil slopes. For the better estimation of the surficial failure, not only the increase of pore-water pressure (reduction of matric suction), but also the influence of water flows over slope surface which erode soil mass, should be evaluated and considered.
A Study on the Measurement of Volumetric Water Content Using WCR in Final Cover Layer of Landfill
Kim Kyung-Chul ; Hwang Koou-Ho ; Lee Song ;
Journal of the Korean Geotechnical Society, volume 21, issue 6, 2005, Pages 147~154
This study deals with the calibration of low-frequency water content reflectometer for measuring the volumetric water content of soils in landfill final cover layer, and the validity of calibrations was evaluated by electrical conductivity and index properties of the soils. Linear calibrations concerning volumetric water content to WCR period provided good agreement with the data. Analysis of the calibration data indicates that the slope of the calibration decreases as the electrical conductivity of the soil increases. Lower slopes correspond to soils with greater clay content, organic content, liquid limit, and plasticity index, which typically have higher electrical conductivity. It could be well explained that WCR can operate in a lower frequency range.