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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 22, Issue 12 - Dec 2006
Volume 22, Issue 11 - Nov 2006
Volume 22, Issue 10 - Oct 2006
Volume 22, Issue 9 - Sep 2006
Volume 22, Issue 8 - Aug 2006
Volume 22, Issue 7 - Jul 2006
Volume 22, Issue 6 - Jun 2006
Volume 22, Issue 5 - May 2006
Volume 22, Issue 4 - Apr 2006
Volume 22, Issue 3 - Mar 2006
Volume 22, Issue 2 - Feb 2006
Volume 22, Issue 1 - Jan 2006
Selecting the target year
Drained and Undrained Pullout Capacity in Steel Strip Reinforced Silty Sands
Lee Hong-Sung ;
Journal of the Korean Geotechnical Society, volume 22, issue 6, 2006, Pages 5~13
Effective stresses may decrease due to generation of excessive pore pressure at the interface between soil and reinforcement in undrained condition such as rapid drawdownof groundwater level, resulting in the decrease in pullout capacity of the reinforcement. In this research, a series of laboratory pullout tests have been performed on different materials (clean sand, 5, 10, 15 and 35% silty sand), different overburden pressures (30, 100 and 200 kPa), and different drainage conditions (drained and undrained) in order to compare drained pullout capacity with undrained pullout capacity. The test results show that both drained and undrained pullout capacity are influenced by silt contents and increase with the increase of friction angle of the soil. The pullout capacity and the pullout displacement required to reach the peak value also increase as the overburden pressure increases. In undrained condition, the effective stresses acting on the reinforcement decrease as excessive pore pressures are generated, resulting in the decrease in pullout capacity and pullout displacement.
A Study on Optimized Artificial Neural Network Model for the Prediction of Bearing Capacity of Driven Piles
Park Hyun-Il ; Seok Jeong-Woo ; Hwang Dae-Jin ; Cho Chun-Whan ;
Journal of the Korean Geotechnical Society, volume 22, issue 6, 2006, Pages 15~26
Although numerous investigations have been performed over the years to predict the behavior and bearing capacity of piles, the mechanisms are not yet entirely understood. The prediction of bearing capacity is a difficult task, because large numbers of factors affect the capacity and also have complex relationship one another. Therefore, it is extremely difficult to search the essential factors among many factors, which are related with ground condition, pile type, driving condition and others, and then appropriately consider complicated relationship among the searched factors. The present paper describes the application of Artificial Neural Network (ANN) in predicting the capacity including its components at the tip and along the shaft from dynamic load test of the driven piles. Firstly, the effect of each factor on the value of bearing capacity is investigated on the basis of sensitivity analysis using ANN modeling. Secondly, the authors use the design methodology composed of ANN and genetic algorithm (GA) to find optimal neural network model to predict the bearing capacity. The authors allow this methodology to find the appropriate combination of input parameters, the number of hidden units and the transfer structure among the input, the hidden and the out layers. The results of this study indicate that the neural network model serves as a reliable and simple predictive tool for the bearing capacity of driven piles.
Variation of Earth Pressure Acting on Cut-and-Cover Tunnel Lining with Settlement of Backfill
Bautista F.E. ; Park Lee-Keun ; Im Jong-Chul ; Lee Young-Nam ;
Journal of the Korean Geotechnical Society, volume 22, issue 6, 2006, Pages 27~40
Damage of cut-and-cover tunnel lining can be attributed to physical and mechanical factors. Physical factors include material property, reinforcement corrosion, etc. while mechanical factors include underground water pressure, vehicle loads, etc. This study is limited to the modeling of rigid circular cut and cover tunnel constructed at a depth of
in loose sandy ground and subjected to a vibration frequency of 100 Hz. In this study, only damages due to mechanical factors in the form of additional loads were considered. Among the different types of additional, excessive earth pressure acting on the cut-and-cover tunnel lining is considered as one of the major factors that induce deformation and damage of tunnels after the construction is completed. Excessive earth pressure may be attributed to insufficient compaction, consolidation due to self-weight of backfill soil, precipitation and vibration caused by traffic. Laboratory tunnel model tests were performed in order to determine the earth pressure acting on the tunnel lining and to investigate the applicability of existing earth pressure formulas. Based on the difference in the monitored and computed earth pressure, a factor of safety was recommended. Soil deformation mechanism around the tunnel was also presented using the picture analysis method.
Deformation Characteristics of Non-liquefied, Reconstituted, Weathered Residual Soils due to the Cyclic Loading
Choi Yeon-Su ; Yune Chan-Young ; Jang Eui-Ryong ; Chung Choong-Ki ;
Journal of the Korean Geotechnical Society, volume 22, issue 6, 2006, Pages 41~49
This paper deals with development and dissipation of excess pore pressure induced by the cyclic load. Cyclic triaxial tests on reconstituted samples of weathered residual soils, which were widely used as construction materials in Korea, were performed. Test results showed that excess pore pressures developed under undrained condition increased with the increase of cyclic loads and confining pressures. And a new concept based on modified excess pore pressure ratio (MEPPR) was proposed for simply estimating excess pore pressures in terms of the number of cyclic load, irrespective of cyclic loads and confining pressures. Also, it was proposed that excess pore pressure ratio (EPPR) could be effectively utilized to estimate volumetric strains during dissipation which decreased as confining pressures increased. Consequently, concept and method to effectively estimate settlements under non-liquefied condition, induced by dynamic loads such as earthquake loads were evaluated based on laboratory test results for reconstituted weathered residual soils.
RSM-based Probabilistic Reliability Analysis of Axial Single Pile Structure
Huh Jung-Won ; Kwak Ki-Seok ;
Journal of the Korean Geotechnical Society, volume 22, issue 6, 2006, Pages 51~61
An efficient and accurate hybrid reliability analysis method is proposed in this paper to quantify the risk of an axially loaded single pile considering pile-soil interaction behavior and uncertainties in various design variables. The proposed method intelligently integrates the concepts of the response surface method, the finite difference method, the first-order reliability method, and the iterative linear interpolation scheme. The load transfer method is incorporated into the finite difference method for the deterministic analysis of a single pile-soil system. The uncertainties associated with load conditions, material and section properties of a pile and soil properties are explicitly considered. The risk corresponding to both serviceability limit state and strength limit state of the pile and soil is estimated. Applicability, accuracy and efficiency of the proposed method in the safety assessment of a realistic pile-soil system subjected to axial loads are verified by comparing it with the results of the Monte Carlo simulation technique.
Evaluation of Bearing Capacity of Multi-layered Soil Deposits
Park Jun ; Jee Sung-Hyun ; Lee Seung-Rae ; Park Hyun-Il ;
Journal of the Korean Geotechnical Society, volume 22, issue 6, 2006, Pages 63~69
In this paper, a method is presented for estimating the bearing capacity of shallow foundations based on the Discrete Element Method (DEM). By applying Winkler-springs for accounting for the compatibility between soil blocks, the proposed method can estimate the state of stress at failure surface and the ultimate bearing capacity. For the investigation of the application of the method, example problems about shallow foundations on the single layer and two layers soil are analyzed.
Reinforcing Effects around Face of Soil-Tunnel by Crown & Face-Reinforcing - Large Scale Model Testing
Kwon Oh-Yeob ; Choi Yong-Ki ; Woo Sang-Baik ; Shin Jong-Ho ;
Journal of the Korean Geotechnical Society, volume 22, issue 6, 2006, Pages 71~82
One of the most popular pre-reinforcement methods of tunnel heading in cohesionless soils would be the fore-polling of grouted pipes, known as RPUM (reinforced protective umbrella method) or UAM (umbrella arch method). This technique allows safe excavation even in poor ground conditions by creating longitudinal arch parallel to the tunnel axis as the tunnel advances. Some previous studies on the reinforcing effects have been performed using numerical methods and/or laboratory-based small scale model tests. The complexity of boundary conditions imposes difficulties in representing the tunnelling procedure in laboratory tests and theoretical approaches. Full-scale study to identify reinforcing effects of the tunnel heading has rarely been carried out so far. In this study, a large scale model testing for a tunnel in granular soils was performed. Reinforcing patterns considered are four cases, Non-Reinforced, Crown-Reinforced, Crown & Face-Reinforced, and Face-Reinforced. The behavior of ground and pipes as reinforcing member were fully measured as the surcharge pressure applied. The influences of reinforcing pattern, pipe length, and face reinforcement were investigated in terms of stress and displacement. It is revealed that only the Face-Reinforced has decreased sufficiently both vertical settlement in tunnel heading and horizontal displacement on the face. Vertical stresses along the tunnel axis were concentrated in tunnel heading from the test results, so the heading should be reinforced before tunnel advancing. Most of maximum axial forces and bending moments for Crown-reinforced were measured at 0.75D from the face. Also it should be recommended that the minimum length of the pipe is more than l.0D for crown reinforcement.