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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
Editor in Chief :
Volume & Issues
Volume 15, Issue 6 - Dec 1999
Volume 15, Issue 5 - Oct 1999
Volume 15, Issue 4 - Aug 1999
Volume 15, Issue 3 - Jun 1999
Volume 15, Issue 2 - Apr 1999
Volume 15, Issue 1 - Feb 1999
Selecting the target year
Reliability-Based Analysis for Rock Slopes Considering Failure Modes
Journal of the Korean Geotechnical Society, volume 15, issue 6, 1999, Pages 3~16
This paper presents the results of sensitivity analysis based on an example study to verify a newly developed reliability-based model for rock slopes considering uncertainties of discontinuities and failure modes-plane, wedge, and toppling. The parameters that are needed for sensitivity analysis are the variability of discontinuity properties (orientation and strength of discontinuities), the loading conditions, and the rock slope geometry. The variability in orientation and friction angle of discontinuities, which can not be considered in the deterministic analysis, has a great influence on the rock slope stability, The stability of rock slopes including failure modes is more influenced by the selection of dip direction of cutting rock face than any other design variables, The example study shows that the developed reliability-based analysis model can reasonably assess the stability of rock slope.
Modeling Strain Rate-dependent Behavior in Consolidation of Natural Clay
Journal of the Korean Geotechnical Society, volume 15, issue 6, 1999, Pages 17~28
In order to analyze effects of strain rate on consolidation of natural clay, this paper presents a nonlinear elasto viscoplastic model in which viscoplastic behavior is modeled by a unique effective stress-strain-strain rate relationship (equation omitted). The predicted values using numerical analysis are compared with measured ones in several laboratory tests such as creep test, multistage load test, and relaxation test for Berthierville clay. It is possible to estimate consolidation behavior of natural clay with reasonable accuracy using the proposed nonlinear viscoplastic model.
Effect of Pile Construction on Lateral Behavior of Single Rigid Pile in Sand
Journal of the Korean Geotechnical Society, volume 15, issue 6, 1999, Pages 29~44
This paper shows the results of model tests on the lateral behavior of single rigid pile, which was constructed by driving, in homogeneous and non-homogeneous (two layered) NakDong River sands. The purpose of the present paper is to investigate the effect of ratio of lower layer thickness to embedded pile length, relative density of sand and pile construction conditions (Driven & Embedded piles) on the characteristics of lateral behavior of single pile. These effects can be quantified only by the results of model tests. As a model result, the lateral behavior depends upon the pile construction condition in loose-density soil more than in high-density soil. If the pile construction depends upon driving construction, the decrease of deflection remarkably increases for both loose homogeneous sand and non-homogeneous soil
with high thickness of upper layer but the decrease of maximum bending moment shows the opposite result to the decrease of deflection. And, with respect to deflection, it was found that the deflection ratio
of embedded to driven piles has the ranges of 0.65 - 0.88
0.38 - 0.65
for each relative density of homogeneous soil and the range of 0.6 - 0.88 for non-homogeneous soil. Also, in this study, the experimental equation for the effects of drop height (DH) and H/L on the ratios of
is suggested from model tests.
Wave-Induced Response of Unsaturated and Multi-layered Seabed; A Semi-analytical Method
;Rahman, M. S.;
Journal of the Korean Geotechnical Society, volume 15, issue 6, 1999, Pages 45~55
Wave-induced response, liquefaction and stability of unsaturated seabed are studied. The unsaturated seabed is modeled as a fluid-filled polo-elastic medium. The coupled process of fluid flow and the deformation of soil skeleton is formulated in the framework of Biot's theory. The resulting governing equations are solved using a semi-analytical method to evaluate the stresses and pore water pressure of unsaturated and multi-layered seabed. The semi-analytical method can be applied to calculate a pore pressure and the stresses of in anisotropic inhomogeneous seabed. The results indicate that the degree of saturation influences mostly on the magnitudes of a pore pressure and the stresses of unsaturated and multi-layed seabed. Based on the pore pressure and stresses in seabed, the analysis on the possibilities of liquefaction and shear failure was performed. The results show that the maximum depth of shear failure occurrence is deeper than the maximum liquefaction depth.
A Study on the Determination of Bearing Capacity of Polluted Soils with Various Concentrations
Journal of the Korean Geotechnical Society, volume 15, issue 6, 1999, Pages 57~69
This study investigates the existing theoretical backgrounds for bearing capacity determination according to the plasticity of soils when unsymmetrical surcharge is loaded on polluted soft soils. It also investigates the behavior of the displacement and bearing capacity by unsymmetrical surcharge on the Polluted soft soils. by comparing the analytical results and the actual measurements performed through the model test. Model tests were carried out as follows : soil tank, bearing frame and bearing plate are made for the test ; the water content in soil tank was kept constant while the contaminants in natural soils and polluted material were gradually increased ; unsymmetrical surcharge is increased at regular intervals and then the amounts of settlement, lateral displacement and upheaval are observed. In conclusion, the value of critical surcharge was expressed as
which was similar to those
had proposed. The value of ultimate capacity was expressed as
which was similar to that of Prandtl.
Analysis of Tensile Force of Nail and Displacement of Soil Nailed Wall at Stepwise Excavation
Journal of the Korean Geotechnical Society, volume 15, issue 6, 1999, Pages 71~86
The displacements of soil nailed wall and the nail tensile force for 11 soil nailing sites were investigated by using measurements obtained from inclinometer and strain gauge. The maximum horizontal displacement which occurred between 5% and 15% of the final excavation depth was found to be below 0.3% and 0.2% of excavation depth for well and poorly constructed sites. It was also found that the maximum horizontal displacements for 0.4%, 0.3% and 0.2% of excavation depth occurred when the ratios of nail length to final excavation depth were 0.5, 0.5~0.6 and 0.6~0.7. But the maximum horizontal displacement increased by 0.3% of excavation depth when the ratio was above 0.7. This was probably due to the shallow excavation depth and the deep soil stratum. The non-dimensional maximum tensile force of nail, K, from ground surface to
of the final excavation depth was less than 0.8 and decreased linearly between
and the final excavation depth. Also, the maximum tensile force was found to reach up to 60% of the ultimate tensile force at final excavation.
for Marine Clay at Southern Part of Korea by Laboratory Consolidation Tests
Journal of the Korean Geotechnical Society, volume 15, issue 6, 1999, Pages 87~98
Consolidation settlements on soft clay are often greatly and potentially damaging to structures. Currently, large-scale projects are in planning or progressing in Korea. These structures will be constructed on both thick and soft clay layers, and so the accurate evaluation of magnitude of settlement is required at every step in design and construction. Especially, secondary compression may play an important role in consolidation settlements of soft clay. Generally, the magnitudes of secondary compression are evaluated by laboratory and in-situ consolidation tests. The empirical
may be economical, fast and powerful tool in estimating secondary consolidation settlement. However, the databases of the
at construction site in Korea are insufficient. The purpose of this study is to investigate the relationship of
on marine clay near the southern sea in Korea. A series of incremental loading consolidation tests (measuring base pore water pressure) is peformed. It was found that the
on undisturbed marine clay is 0.0397.
Leachate Behavior within the Domestic Seashore Landfill(I)- Hydrogeologic Property Identification through In-situ Tests -
Journal of the Korean Geotechnical Society, volume 15, issue 6, 1999, Pages 99~109
In the case of domestic general waste landfills, cumulated leachate level is often formed in the landfill due to the waste of high moisture content and it becomes important to characterize the hydraulic properties of the disposed waste. Although many hydrologic studies have been peformed for leachate barriers and pheriperal subsurface environments, few studies have been done to investigate the hydraulic property of the disposed waste and cover soils and to analyse the leachate flow behavior within landfills. In this paper, the geotechnical properties of the waste and buried cover soils are identified through the field experiment including pumping and slug tests. The results of various tests show that the field density of the cover soils is somewhat higher than the maximum laboratory density of cover soils and the vertical flow of leachate and gas in the landfill is prevented by the buried cover soils. The hydraulic conductivities of field pumping test and slug tests are well matched and stayed in the range of hydraulic conductivities of well compacted wastes in the literature.
Leachate Behavior within the Domestic Seashore Landfill(II)- Numerical Analysis of Pumping Method for Reducing Leachate Level -
Journal of the Korean Geotechnical Society, volume 15, issue 6, 1999, Pages 111~120
Leachate flow behavior due to intermediate cover soil of low hydraulic conductivity and the applicability of pumping method for reducing the leachate level in the landfill are analyzed with the numerical flow model, MODFLOW. Using the hydraulic conductivity and storativity data obtained from the field pumping and slug tests(Jang and Cho, 1999), the hydraulic condition within the landfill is validated. The optimum rate of pumping, the radius of influence, and the efficiency of horizontal drain are analyzed for reducing the leachate level in the landfill. From the results of the analyses, the barrier effect that the buried cover soil of low hydraulic conductivity prevents the vertical movement of leachate flow through the cover soil, which is found from the in-situ geotechnical studies(Jang and Cho, 1999), is identified again. Also, the installation of horizontal drains to the pumping well can increase the pumping rate from 120 ton/day per a well to 300 ton/day. The length of horizontal drain did not influence significantly on the drawdown-time curve of leachate in the landfill.
Undrained Analysis of Soft Clays Using an Anisotropic Hardening Constitutive Model: I. Constitutive Model
Journal of the Korean Geotechnical Society, volume 15, issue 6, 1999, Pages 121~130
The objective of this study is to perform finite element analyses(FEA) using the anisotropic hardening constitutive model on the basis of the total stress concept. An anisotropic hardening model was then developed to solve the problem and its mathematical formulations and experimental verifications were also described. In a companion paper, the constitutive equation will be formulated for accurate and efficient solutions of FEA, and coded into a nonlinear analysis program, and finally a field problem will be analyzed. The proposed model includes the failure criterion of a von Mises type and the anisotropic hardening rule based on the generalized isotropic hardening description, which can model the nonlinearity and the anisotropy of the stress-strain relationship. As a result this study could verty the experimental results for UU triaxial tests, CU triaxial tests for overconsolidated samples, and anisotropic loading tests with the rotation of principal stress axes for
Undrained Analysis of Soft Clays Using an Anisotropic Hardening Constitutive Model: II. Numerical Analysis
Journal of the Korean Geotechnical Society, volume 15, issue 6, 1999, Pages 131~142
The objective of this study is to perform finite element analyses using the anisotropic hardening constitutive model on the basis of the total stress concept. An anisotropic hardening constitutive model had been developed in a companion paper, and was then formulated by implicit stress integration and consistent tangent moduli. A nonlinear finite element analysis program was coded including the algorithm, and as a result, the nonlinear solution was accurately calculated and converged to be asymptotically quadratic. In the analysis of a test embankment it was found that the proposed model could predict the displacement of soils more reasonably than the analysis with von Mises type model. In addition the proposed model could predict accurately the actual behavior through the reanalysis of the problem by a reasonable evaluation of the strength parameter.
Rock Anchors Subjected to Static Uplift Loads ; Shear Stress Distribution of Tendon-Grout Interface
Journal of the Korean Geotechnical Society, volume 15, issue 6, 1999, Pages 143~154
In this study, the load transfer mechanism of tendon-grout interface of rock anchors has been examined through a series of static pull-out tests conducted on the model rock anchors constructed in the natural and artificial rock masses of granite and concrete, respectively. Several rock masses with horizontal discontinuities have been prepared to study the effects of weak planes on the shear stress distribution in tendon-grout interface. As a result, for the rock anchors constructed in the rock mass without discontinuities, stress concentration occurs on the upper part of the tendon-grout interface. On the contrary, as the frequency or the number of discontinuities increases, the shear stress distribution along the depth tends to be uniform. Also, an experimental equation about shear stress distribution between tendon-grout interface can be made by the regression of test results. The shear stresses computed from the experimental results between the rock surface and the depth of 2~3 times the tendon diameter are smaller than those from theory. Below the depth, the reverse can be observed.
Bearing Capacity of Cast-in-situ Concrete Piles Socketed in Completely Weathered Gneiss
Journal of the Korean Geotechnical Society, volume 15, issue 6, 1999, Pages 155~165
In completely weathered granite gneiss,8 of 40cm cast-in-situ concrete piles are constructed, and static pile load tests are executed on the piles to study the bearing behavior of rock-socketed piles. Subsurface explorations are carried out on the test site in three phases, in which 14 borehole investigations as well as the seismic investigation are performed. Rock socketd depths of the piles in the weathered rocks are varied as 3m, 6m and 9m to separate the shaft resistance from the end bearing resistance, and for a couple of piles, styrofoam of 10cm thickness is installed under the pile point to eliminate the effect of the end resistance. Strain gages are instrumented on re-bars to pick-up the transferred loads along the pile length. From the results of the pile load tests, the allowable shaft resistance and the allowable end bearing values of weathered rocks are proposed as
, respectively. The empirical equation relating the elastic modulus of rock mass with the uniaxial compressive strength of the rock specimen is also proposed for the weathered rocks.
Lateral Behavior of Single Rigid Driven Pile in Non-Homogeneous Sand
Journal of the Korean Geotechnical Society, volume 15, issue 6, 1999, Pages 167~185
A series of model tests was performed to find the characteristics of lateral behavior of single rigid pile. This paper shows the results of model tests on the lateral behavior of single rigid driven pile in non-homogeneous(two layered) Nak-Dong River sands. The purpose of this paper is to investigate the effect of the ratio of lower layer thickness to embedded pile length, the coefficient ratio of the subgrade reaction and the pile construction conditions(driven & embedded piles) on the characteristics of lateral behavior of single pile. The results of model tests show that the lateral behavior in non-homogeneous soil depends upon drop energy considerably, that is, in the case of H/L=0.75, as the drop energy increases three times the decrease percentage increases about 2.12 times. In the driven pile with non-homogeneous soil of
, the effect of upper layer with large stiffness on the decrease of lateral deflection is remarkably smaller than embedded pile. In non-homogeneous soil, the maximum bending moment of driven pile is in the range of 100 132% in comparison with embedded pile. The reason is that the stiffness of soil around pile increases with drop vibration and so the pile behavior is similar to the flexible pile behavior by means of the increase of relative stiffness of pile, In this paper, the experimental equations for lateral load and H/L on
A Relation between Anchor Unbonded Length, Anchor Loads, and Wall Deflection in Tieback Anchored Wall
Journal of the Korean Geotechnical Society, volume 15, issue 6, 1999, Pages 187~200
An extensive investigation is performed to analyze the behavior of tieback anchored wall. Finite element method is used and several case histories are collected to investigate the relationship of wall deflection, anchor unbonded length, and anchor load. The finite element method can calculate wall deflection with changing the anchor unbonded length and the anchor load. Wall deflection normalized by excavation height can be related to anchor location so that it may produce a zone chart. It is found that a different chart showing the relation of the wall deflection, the anchor load, and anchor unbonded length can be constructed. It is necessary to collect more case histories considering soil conditions and to perform FE analysis extensively with changing bonded length to extend the capability of this relation chart into practice.
A Study on Bearing Capacity according to the Number of Reinforcement Layers in Sandy Ground Reinforced by Mats of Equal-intervals
Journal of the Korean Geotechnical Society, volume 15, issue 6, 1999, Pages 201~217
Bearing capacity of soil can be improved by several conventional ground improvement techniques like stabilization and compaction. In recent time, the use of reinforced soil has become popular due to the availability of durable strong geosynthetic materials. In this papers, through the laboratory model tests on sandy ground reinforced by mats about the strip footing under plane strain condition, the effects of bearing capacity improvement and behaviour of sandy ground were observed. And bearing capacities calculated by proposed method and measured by tests were compared.
A Study on Characteristics of the Desiccation Shrinkage in Reclaimed Hydraulic Fills
Journal of the Korean Geotechnical Society, volume 15, issue 6, 1999, Pages 219~238
In the present study, laboratory tests including the seepage-induced consolidation test, suction test, and desiccation shrinkage test are performed to investigate characteristics of the desiccation shrinkage in reclaimed hydraulic fills. Soil samples for laboratory tests are obtained from three sites (districts of Haenam, Kogeum and Koheung in Chunnam area). Desiccation shrinkage settlement caused by three dimensional volume change is numerically evaluated using finite difference technique based on the governing equation proposed by Abu-Hejleh & Znidarcic. Also characteristics of the desiccation shrinkage analyzed from the test results are used as input data for numerical evaluations. Further predicted total settlements including the self-weight consolidation settlement are compared with values measured at the site of Haenam district. Finally, effects of parameters related to the desiccation shrinkage on settlements are examined.
Analysis of Passive Pile Groups Subjected to Lateral Soil Movements-A Study on the Model Test-
Journal of the Korean Geotechnical Society, volume 15, issue 6, 1999, Pages 239~249
In this study, experimental work has been carried out to investigate the effect of lateral soil movement on passive piles. This paper consists mainly of two parts: the first, performance of a series of laboratory experiments on a single pile and one-row pile groups, and the second, comparison between the measured and the predicted results. In the laboratory experiments, a quadrilateral soil movement profile was imposed on model piles embedded in both sandy soils and weathered soils. The maximum bending moment and pile deflection induced in passive piles were found to be highly dependent on pile stiffness, pile spacing, relative densities and pile head fixity condition. It was shown that the group effect might either increase or decrease the maximum bending moment and pile deflection, depending on the aforementioned influence factors. Based on the results obtained, a spacing-to-diameter ratio of 7.0 seems to be large enough to eliminate the group effect, and a pile in such a case behaves essentially the same as a single pile.
A Study on the Improvement of Connection for Shield Tunnel Lining Using Trapezoidal Segments
Journal of the Korean Geotechnical Society, volume 15, issue 6, 1999, Pages 251~262
The assemblage of the trapezoidal segments, which is being used increasingly to shield tunnelling, with Guide rod and Dowel forms tunnel lining. In this case the larger the taper angle of trapezoidal segment is, the easier the assembly work becomes. The large angle can reduce the water proof material's phenomenon of being pushed back, but decreases the structural safety in connecting section of tunnel lining. In this paper a 3-dimensional numerical analysis was performed to estimate the exact behavior of a model shield tunnel made by connecting 3-dimensionally various accessories with irregular sectioned segments. We obtained the operating force of connecting section according to the change of taper angle of trapezoidal segment and sought for improved scheme for connecting section by comparing and analyzing the test results on the friction resistance force of connecting parts.
Slope Stability Analysis by Slice Method and Finite Difference Method- A Comparative Study -
Journal of the Korean Geotechnical Society, volume 15, issue 6, 1999, Pages 263~272
Slice method is commonly used in solving slope stability problems since it is easy to use and its computation time is rather short. But depending upon the assumptions on the inter-slice forces, different methods are available. Quite often the difference between methods are so big that it is very difficult to make engineering decisions. This paper describes a method to calculate the factor of safety of a slope using FLAC, a finite difference based program. A FISH routine is developed to calculate the factor of safety, and verified by comparing with Chen's limit equilibrium solution. An example problem was selected from Fredlund and Krhan's paper, and results were compared for different soil and water conditions. The difference was less than 0.01 when the soil is homogeneous, and less than 5 % when a weak layer is embedded. Since most geotechnical application programs are capable of considering complicated ground conditions as well as the effect of ground supports, numerical methods are believed to be very useful in making engineering decisions. The developed routine can be applied to the calculation of the factor of safety of jointed rock slopes or weathered rock slopes where the use of slice method is limited.
Permeability Reduction of Soils by Biomass Injection
Journal of the Korean Geotechnical Society, volume 15, issue 6, 1999, Pages 273~283
When microorganism is injected into porous medium such as soils, biomass is retained in the pore. Soil pore size and shape are varied from the initial condition as a result of biofilm formation which makes hydraulic conductivity reduced and friction rate between soil aggregates increased. In this research, hydraulic conductivity reduction was measured after microorganism are inoculated and cultured with synthetic substrate and nutrient. In addition, this research evaluated the applicability of biomass-soil mixture to the field condition as an alternative cover material in landfill by measuring hydraulic conductivity change after repetitive freeze-thaw cycles. Hydraulic conductivity of silty soil decreased by approximately 1/50 after biomass inoculation and cultivation. Biofilm attached on soil aggregates is resistant to acidic or basic condition. After repetitive freeze-thaw cycles, however, hydraulic conductivity increase implies that biomass clogging can be impaired.
A Study on the Stability Analysis of Reinforced Embankment on the Soft Ground
Journal of the Korean Geotechnical Society, volume 15, issue 6, 1999, Pages 285~296
Preloading method is used to prevent the settling of a foundation and to increase the strength of ground by consolidation settlement in advance. But, the embankment used in preloading method brings large deformation and sliding failure in the soft ground. Recently, reinforcement method is often used in embankment in order to prevent sliding failure. But, until now, the research on the stability analysis considering both the rate of strength increase of clay by embankment load and increase of resistance force by the geosynthetics in the embankment body is not found. In this study, the stability analysis program(REAP) for embankment including these two points is developed. By this program(REAP), the stability analysis can be done about during the gradual increase of embankment and the stability counterplan can be established when the safety factor is lower than allowable safety factor of design. After calculating the position of sliding failure surface, the force of geosynthetics which is selected by either the effective tensile strength or tensile force caused by the displacement of soil mass in this position is applied to stability analysis. And the increase of resisting moment can be calculated by this force. Also, the construction period can be estimated and the time for the appropriate counterplan can be decided in order to maintain the stability of embankment. And then, safe and economical embankment design can be performed.
A Thermodynamic Study on Freezing Characteristics of Weathered Tuff Soil- Freezing Point Depression with the Variation of Overburden Pressure -
Journal of the Korean Geotechnical Society, volume 15, issue 6, 1999, Pages 297~306
In this research, the frost heave mechanism of the weathered tuff soil sampled from the area tying between Ulanbator and Beijing was studied. The frost heave tests were carried maintaining the constant temperature at both upper
ends of the sample. Here, main emphasis is given on variation of the freezing point depression with the variation of applied overburden pressure. The expansion of ice lens and migration of the pore water towards freezing front were observed in the test. It was found that with the increase in overburden pressure there is decrease in heave rate and increase in the absolute value of a segregation-freezing temperature. Hence the equation between segregation-freezing temperature and overburden pressure could be suggested. Also the water content of the samples at the frozen side was shown to be higher than those at the unfrozen side. Similarly, the water at warmer part of the frozen tuff was found much higher than that of the cooler part.
Evaluation of Liquefaction Strength Based on Korean Earthquake Magnitude
Journal of the Korean Geotechnical Society, volume 15, issue 6, 1999, Pages 307~317
The purpose of this study is to utilize conventional procedures for evaluation of liquefaction potential and to compare the results obtained by modified detailed method based on Korean earthquake magnitude (M=6.5). Liquefaction potential is assessed by comparing liquefaction strength of soil and cyclic shear stress generated in the soil layers during earthquakes. The cyclic shear stress is computed from the earthquake response analysis, and liquefaction strength of soil is evaluated by using results from cyclic triaxial tests. The cyclic triaxial tests are performed on many different conditions of sample ; relative densities(50%, 60%, and 70%), initial effective confining pressures (70kPa, 100kPa, and 150kPa), and fine contents(10%, 20%, and 30%). From the result of comparing the conventional procedure with the modified detailed method, it is found that the modified detailed method tends to evaluate larger safety factor against liquefaction in the weak sand site
. Therefore in this case, it is suggested that liquefaction potential should be evaluated by using the modified detailed method based on cyclic triaxial tests. It is also found that in modified detailed method based on earthquake magnitude 6.5, critical depth where liquefaction can be generated is around 15m from the ground surface.