• Geotechnical Engineering
• /
• v.1 no.1
• /
• pp.5-12
• /
• 1985

Ocassionally it is used for simple extensions of Terzahgi's theory to account for time-depend- tint loading but there is little evidence of application in more complicated consolidation theories that take into account such effects as nonlinear stress.strain, layered systems or large strains. The purpose of this paper provides an efficient computer algorthm based on numerical analysis using finite difference method which account for multi-layered soils to determine the degree of consolidation and excess pore pressures relative to time and positions more realistically. The explicitly scheme of solving the consolidation equations has been investigated from the point of view of the stability conditions and the convergence with variance of the operator as well as to obtain an optimal divided depth ratios of total depth. A comparison of the settlement predictions with both the classical analysis and the algorithm based on numerical analysis indicates that the new algorithm scheme is found to be superior to the classical theory in the layered soils.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2010.03a
• /
• pp.495-508
• /
• 2010

Vertical drains are commonly used to accelerate the consolidation process of soft soils, such as dredged materials. The installation of vertical drain provides a radial drainage path to water in the deposit soil in addition to the vertical direction. An estimation of time rate of settlement is considerably complicated when vertical drains are installed to enhance consolidation process of dredged material because the vertical drains are commonly installed before self-weight consolidation is ceased. In this paper, the vertical drain theory developed by Barron(1948) is applied to analyze the non-linear consolidation behavior considering radial drainage. The overall average degree of self-weight consolidation of the dredged soil under the condition that the water is drained in both radial and vertical directions is estimated using the Carillo(1942) formula. In addition, the Morris(2002) theory and the one-dimensional non-linear finite strain numerical model, PSDDF, are applied to analyze the self-weight consolidation in case of only the vertical drainage is considered. The new analysis approach proposed herein can simulate properly the time rate of the self-weight consolidation of dredged materials that is facilitated with vertical drains.

• Journal of the Korean GEO-environmental Society
• /
• v.18 no.6
• /
• pp.39-44
• /
• 2017

The behavior of the lateral resistance beyond the yield condition on single pile has been evaluated by comparative analysis. Pushover analysis of single pile has been performed to compare to the results on lateral load test of the pile foundation. The study for the behavior beyond the yield condition on single pile had been performed on the results on the lateral load test and pushover analysis considering mechanical conditions of the ground soil and the pile foundation.

• Geotechnical Engineering
• /
• v.12 no.5
• /
• pp.63-78
• /
• 1996

Various type of in-situ and laboratary tests were performed in order to evaluate the stiffness of sedimentary soft rock. In triaxial compression tests of sedimentary soft rocks, axial strains from the axial displacement of the loading piston or specimen cap conventionally were considerably larger than those measured. tocally on the lateral surfaces of specimen, due to the bedding errors at the top and bottom ends of a specimen. A local deformation transducer was used to measure axial strains free from the bedding error ranging from 0.001% to about 1%. In ultra-sonic wave tests, the elastic modulus of unconfined spec imens was smaller than that of confined specimens, due probably to microfracks. Young's modulus Ed from ultra-sonic wave tests and those at small local strains from triaxial tests were similar, both of which agreed very well with Young's modulus Er from field shear wave velocities. Young'a modulus from the field behaviour was virtually similar to that obtained by reducing Er based on the strain level-dependency of stiffness evaluated by the triaxial tests.

• Journal of the Korean Geosynthetics Society
• /
• v.13 no.3
• /
• pp.39-47
• /
• 2014

In this study, the full scale model tests were performed with track-roadbed system such as Ho-nam high speed railway. The measured data gives good similar a roadbed pressure with equivalent depth to the Odemark's theory. In the case of earth pressures have a under 50 kPa at upper-subgrade applying 330 kN static loading. Results of cyclic loading tests did not differ significantly from those of static loading test. The elastic displacement at HSB layer has a level of 1/100 compared to the 1 mm that it was evaluation criteria for speed up of High Speed Railway. Elastic displacement at subgrade layer was measured a level of 1/175. The dynamic characteristics of track-roadbed with loading frequency level were linearly increased under 35 Hz, while the wheel loading, displacement and acceleration of roadbed were decreased loading frequency above 35 Hz.

• Journal of the Korean Geotechnical Society
• /
• v.19 no.3
• /
• pp.93-104
• /
• 2003

The Disturbed State Concept (DSC) model, with simplified unloading/reloading formulation, is implemented in a nonlinear dynamic finite element program fur porous media named DSC_DYN2D. In this research, the DSC constitutive model is utilized using the HiSS model for relative intact (RI) part and the critical state model for the fully adjusted (FA) part in the material. The general formulation for implementation is developed. The cyclic loading tests from the field load test data on a pile segment were numerically simulated using the finite element program DSC_DYN2D and compared with field measurements and those from the previous analysis with the HiSS model. The DSC predictions show improved agreement with the field behavior of the pile compared to those from the HiSS model. Overall, the computer procedure with the DSC model allows improved and realistic simulation of the complex dynamic soil-structure interaction problems.

• Journal of the Korean Geotechnical Society
• /
• v.37 no.7
• /
• pp.5-12
• /
• 2021

When drilling investigations for Rock Slopes are not possible, it is often difficult to calculate the Ground Design Constants required for the Limit Equilibrium Analysis. Therefore, the outcrops or partially cutted Rock Slopes were analysed using JRC and JCS that can be easily and conveniently measured. In particular, the effect of the JRC on the Safety Factor or the Rock Slopes was analyzed intensively, and the results were presented as a relationship formula and Table. When the Rock slope was stable, the JRC increased by an average of 9.0% as the slope height increased, and increased by an average of 29.8% as the slope angle increased. JRC was more sensitive to slope angle changes. The Cohesion corresponding to JRC was calculated from JRC-Fs formula. JRC and Cohesion showed a nonlinear relationship, and the Cohesion was about 8.0% more sensitive to slope height changes than slope angle changes.

• Journal of the Korean Geotechnical Society
• /
• v.24 no.1
• /
• pp.61-70
• /
• 2008

The control and prediction of surface settlement, gradient and ground displacement are the main factors in shallow tunnel design and construction in urban area. For deformation analysis of shallow tunnel due to excavation it is important to identify possible deformation mechanism of shear bands developing from tunnel shoulder to the ground surface. This paper investigaties quantitatively the deformation behavior of shallow tunneling by model tunnel test and strain softening analysis Incorporating the reduction of shear stiffness and strength parameters. The comparison of model tunnel test result and numerical simulation using strain softening analysis showed good agreement in crown settlement, normalized subsidence settlement and developing shear bands above tunnel shoulder. In this study, it is blown that the strain softening modeling is applicable to the nonlinear deformation analysis of shallow tunnel.

• Journal of the Korean Geotechnical Society
• /
• v.30 no.9
• /
• pp.19-28
• /
• 2014

It is necessary to understand the behavior of the soils for the dredging constructions. The objective of this study is to estimate void ratio and density changes of the dredged soils by using the geophysical testing methods. A series of laboratory tests is performed to obtain geotechnical index properties of the specimen, retrieved from the west coastal of Korea. The sedimentation and self-weight consolidation tests are carried out with observing changes of the interfacial height and the elastic wave velocities. The same amounts of the soils are poured into the testing column at intervals of 12 hours until the interheight reaches to a certain level. After the completion of the sedimentatation and self-weight consolidation tests, downward permeability test is performed to assess a tidal influence in the nearshore. The mini resistance cone is penetrated into the specimen to measure the electrical resistivity with depth. All tests are completely finished, the weight of specimens are measured to calculate the void ratio with the depth. Experimental results show that the aspects of the self-weight consolidation are invisible during dredging process because of rapid sedimentation characteristics of ML. However, the elastic wave velocities increase with increasing in the effective stresses. During permeability test, measured permeability and the elastic wave velocities maintain almost identical values. Void ratio based on the elastic wave velocities changes linearly with time during the step dumpings. Void ratio estimated by the electrical resistivity represents the repeatedly layered depositions according to the step-by-step dumpings. Void ratio determined by soil sampling is similar to those of elastic waves and electrical resistivity profiles. This experimental study demonstrates that the geophysical testing methods may be an effective method for evaluating the behavior of dredged soils.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2000.10a
• /
• pp.132-139
• /
• 2000

This paper presents a new hybrid approach for nonlinear dynamic analysis of the soil-structure interaction system in the time domain. It employs, in a practical manner, a linear SSI program and a general-purpose nonlinear finite element program. In order to demonstrate the validity and applicability of the proposed method, seismic response analyses are carried out for a free-field problem and a 2-D subway station. The results indicate that the proposed methodology gives reasonable solution for the linear/nonlinear SSI problem utilizing a general-purpose finite element program. Some further studies will endorse the applicability of the method to various soil-structure interaction problems.