• Journal of the Korean GEO-environmental Society
• /
• v.5 no.3
• /
• pp.17-30
• /
• 2004

In this study, a new formula of settlement at the head of IGM was suggested and the applicability of suggested formula was verified with field test results. This suggested formula was the function of the settlement at the shaft head and the elastic compression of shaft. The applicability of suggested formula was verified with the result of in-situ load test. Also, the bearing capacity of drilled shaft with the IGM's theory was compared with those of classical theories. The results showed that classical method showed smaller values of bearing capacity than those of field load test data. The results of analysis also showed that the suggested formula and IGM's theory were applicable for the estimation of bearing capacity with the increase of shaft settlement. Especially, settlement correction factor($k_m$), which reflects ground condition and load transfer characteristics, increases as the applying load and shaft deformation increase. This suggested formula was applicable for medium density or higher density of soil condition and $k_m=1$ means yielding load for firm soil condition.

• Journal of the Korean Geotechnical Society
• /
• v.18 no.4
• /
• pp.7-19
• /
• 2002

This paper presents the results of an investigation on the effect of foundation stiffness on the performance of soil-reinforced segmental retaining walls (SRWalls). Laboratory model tests were performed using a reduced-scale physical model to capture the fundamentals of the manner in which the foundation stiffness affects the behavior of SRWalls. A series of finite-element analyses were additionally performed on a prototype wall in order to supplement the findings from the model tests and to examine full-scale behavior of SRWalls encountered in the field. The results of the present investigation indicate that lateral wall displacements significantly increase with the decrease of the foundation stiffness. Also revealed is that the increase in wall displacements is likely to be caused by the rigid body movement of the reinforced soil mass with negligible internal deformation within the reinforced soil mass. The findings from this study support the current design approaches, in which the problem concerning the foundation condition are treated in the frame work of the external stability rather than the internal stability. The implications of the findings from this study to current design approaches are discussed in detail.

• The Journal of Engineering Geology
• /
• v.17 no.1 s.50
• /
• pp.65-73
• /
• 2007

Recently, large-scale underground cavern such as underground hydraulic-power plant tend to be constructed very largely, so long-length rock bolt are generally used to support the huge plastic zone. However, problems fur bend-ing shape of the long-length steel bar and the bonding effects of anchoring systems are caused during the construction of the long-length rock bolt. In this study, field pull-out test for long-length rock bolt are carried out to estimate the most efficient anchoring system among the saw-toothed shape, grooved shape and smoothed shape with each 6 shells for 5.0m, 7.5m, 10.0m, 15.0m length. The axial load and axial displacement are measured with each load stage and than test results are analyzed to evaluate the behavior characteristics for each anchoring systems of long-length rock bolt. Also, the improvements of anchoring systems are proposed and discussed in this paper.

• Journal of the Korean Geotechnical Society
• /
• v.20 no.7
• /
• pp.25-32
• /
• 2004

This paper examines the results of full-scale field tests on micropiles and side resistance is evaluated with respect to axial displacements and soil properties. Both cohesive and cohesionless soils are included in this evaluation. For all practical purposes, the developed load-displacement relationship and the geotechnical soil properties for each micropile and soil type can be used to represent the available data well through normalized average values and empirical correlations. There is a significant difference in load-carrying capacity between micropiles and drilled shafts that results primarily from the micropile pressure-grouting installation effects on the state of stress in the ground. The results show that micropiles can have a significant increase of capacity over larger-diameter drilled shafts at shallower depths with D/B < 100 or so. In cohesive soils, the typical increase is on the order of 1.5 with values as high as 2.5. For cohesionless soils, the typical increases are in the range of 1.5 to 2.5 with values as high as 6.

• Geotechnical Engineering
• /
• v.11 no.1
• /
• pp.63-78
• /
• 1995

Recently, in order to utilize more effectively underground space, deep excavations have been performed on building or subway construction in urban areas. In such excavations, anchors have been used to support the excavation retaining walls because the anchored excavation could provide wide working space for underground construction. The purpose of this paper is to establish empirical equations to be able to estimate the earth pressures acting on anchored excavation retention walls, based on the investigation of field measuring results, which were obtained from twenty seven building construction sites. The prestressed anchor force was measured by load cells which were attached to the anchor head, while the horizontal displacement of excavation walls were measured by inclinometers which were installed right'behind the retention walls. The lateral earth pressures acting on the anchored retention walls, which were estimated from both the measured anchor forces and the horizontal displacement of the walls, showed a trapezoidal distribution. There was some difference between the measured earth pressures acting on the anchored retention walls and the empirical earth pressures given by several empirical equations. Thus, the lateral earth pressures acting on anchored retention walls would be estimated by these empirical equations with some modifications.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.34 no.3
• /
• pp.711-721
• /
• 2014

PPWS, a large number of which a main cable of a suspension bridge consists of, must be precisely erected at a target location under construction considering the differences among design conditions. The absolute sag is measured for several PPWSs, which are reference strands and the relative sag is surveyed from them to other PPWSs, which are divided into several groups. And the adjustment of PPWS length is performed to erect it at target configuration. When PPWS is being under erection in a real bridge site, the procedures are as follows; evaluate sag sensitivities according to sag variation factors, calculate an adjustment length of PPWS corresponding to them and adjust a sag of PPWS by controlling the calculated amount of PPWS length. In this study, the differential-related equations of sag sensitivity were proposed for support movement of PPWS. Before site demonstration study of a series of them, we established a catenary model system and accomplished verification tests of them. From test results, the validation of them was done.

• Journal of the Korean Geotechnical Society
• /
• v.27 no.12
• /
• pp.97-106
• /
• 2011

To analyze the lateral load-deflection behavior of steel-concrete composite drilled shafts, a series of lateral pile load tests were performed. The test results were compared with the results from various analytical methods for lateral pile behaviors using the coefficients of subgrade reaction ($k_h$) estimated by pressuremeter test (PMT) and standard penetration test (SPT). As a result, it was found that the analytical methods using the $k_h$ estimated by SPT N value were not suitable for evaluating the pile head lateral load-deflections of the piles within the allowable deflection. However, the methods using the $k_h$ calculated from PMT were able to represent the initial lateral behavior at the head of the piles fairly well. Also, the method by the pressuremeter curve, which was applied directly to the p-y curve of the piles, offered a reasonable lateral behavior estimation by applying the correction factor to the pile materials.

• Journal of the Korean Geosynthetics Society
• /
• v.2 no.2
• /
• pp.3-11
• /
• 2003

Researches on the induced trench method using compressible materials such as clay, mud, straw, or EPS block have been performed to reduce the load acting on buried conduits under a high fill. The induced trench method has the problems that the arching area due to the compressible arching material is one dimensional or localized in a narrow zone. The main purpose of this study is to solve the problems of the induced trench method mentioned above. The various types of laboratory model tests are conducted to find the effects of the variations of EPS block width, multilayer application, soil density, and diameter of the flexible steel pipe. A series of model tests was conducted to evaluate the reduction of earth pressure on conduits using EPS block. Based on modeling test it is found that the magnitude of vertical earth pressure on conduits was reduced about 60% compared with conventional flexible conduit systems.

• Journal of the Korean GEO-environmental Society
• /
• v.8 no.4
• /
• pp.5-11
• /
• 2007

In this study, several pullout tests were carried out under various field conditions to evaluate the pullout force of the end fixed nails. Pullout resistance force, displacement and friction force between the grouting and nail were measured in end fixed nails installed in soft rock, weathered rock and weathered soil. Furthermore, the field test were also carried out under the same condition using the conventional type nails. Based on the test results, it is concluded that the end fixed nails showed larger ultimate resistance force compared with conventional types nails, approximately two times in weathered soil and 1.6 times of weathered rock, respectively. The skin friction is also increased in end fixed type about 1.8~3.0 times. Finally, it is concluded in the base of the force transfer properties that using the end fixed nails could decrease the displacement and show a uniform resistance in entire length of nails.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.7 no.3
• /
• pp.215-222
• /
• 2003

Recently the deep and large excavations are performed near the existing buildings in urban areas for the practical use of underground space. The earth pressure due to the excavation are varied according to the conditions of ground, the depth of excavation, the construction methods, and the method of supporting the earth pressure etc.. In this study, not only the behavior of axial load and distribution of earth pressure on the flexible wall according to stage excavation depth but also magnitude and distribution of lateral deformation, and the equivalent earth pressure from strut axial loads were analyzed by the results measured from instruments such as, load cells, strain gauges, and in-situ inclinometer, on the field of subway construction. According to the results of this study in the case of stage excavation the earth pressure of soft clayey soil is compounded with Terzaghi-Peck and Tschebotarioff.