• Proceeding of KASS Symposium
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• 2008.05a
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• pp.203-211
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• 2008

Bridges have various functions. There are not only a connection between 2 zones, but also a objee as a landmark. But movable bridges used in canal in order to pass ships. We can classify according to type of driving system, for example, swing, bascule, lift, arching, rotation, etc. I will suggest classification of various driving mechanism in the world.

• Geotechnical Engineering
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• v.5 no.4
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• pp.27-36
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• 1989

Load tests are executed on instrumented model piles to evaluate the magnitudes of soil plugging resistances mobilized at open-end pile tips. The plugging resistances are calculated by some existing methods, which are compared with observation. A couple of the methods are found to give good results. A new computational method to predict the plugging resistance is proposed in this paper, which also gives fairly close prodiction to the measurement, and is much simpler than the other computational methods.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.3
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• pp.133-149
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• 2021

This study aims to report the behavioral mechanism of steel pipe reinforcement grouting, which is being actively used to ensure the stability of the excavation surface during tunnel excavation, based on measurements taken at the actual site. After using a 12 m steel pipe attached with a shape displacement meter and a strain gauge to reinforce the actual tunnel surface, behavioral characteristics were identified by analyzing the measured deformation and stress of the steel pipe. Taking into account that the steel pipes were overlapped every 6 m, the measured data up to 7 m of excavation were used. In addition, the behavioral characteristics of the steel pipe reinforcement according to the difference in strength were also examined by applying steel pipes with different allowable stresses (SGT275 and SGT550). As a result of analyzing the behavior of steel pipes for 7 hours after the first excavation for 1 m and before proceeding with the next excavation, the stress redistribution due to the arching effect caused by the excavation relaxation load was observed. As excavation proceeded by 1 m, the excavated section exhibited the greatest deformation during excavation of 4 to 6 m due to the stress distribution of the three-dimensional relaxation load, and deformation and stress were generated in the steel pipe installed in the ground ahead of the tunnel face. As a result of comparing the behavior of SGT275 steel pipe (yield strength 275 MPa) and SGT550 steel pipe (yield strength 550 MPa), the difference in the amount of deformation was up to 18 times and the stress was up to 12 times; the stronger the steel pipe, the better it was at responding to the relaxation load. In this study, the behavior mechanism of steel pipe reinforcement grouting in response to the arching effect due to the relaxation load was identified based on the measured data during the actual tunnel excavation, and the results were reported.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.11
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• pp.479-486
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• 2019

The caps foundation method can reduce the load of a building by using the arching effect, but verification of the method is still insufficient. In this paper, a model test was performed to quantitatively prove the load reduction effect by this method. The test was carried out using six conditions according to the size of caps foundation block and the area of the loading plate. The test results show that the earth pressure was the highest at the position closest to the loading point regardless of the size of caps foundation block and the area of the loading plate. At the highest earth pressure position, when the loading plate area was 30 cm × 30 cm, the earth pressure of a small block was reduced by 35.4% on average, and that of a big block was reduced by 39.7% compared to the pressure with no block. When the loading plate area was 60 cm × 60 cm, the earth pressure of the small block was reduced by 33.9% on average, and the earth pressure of the big block was reduced by 42.7%. Therefore, if the caps foundation method is applied, the load will be reduced by more than 33% for a small block and 39% for a big block.

• Journal of the Korean Geotechnical Society
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• v.32 no.12
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• pp.79-91
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• 2016

Geosynthetic-reinforced and Pile-supported (GRPS) embankment method is widely used to construct structures on soft ground due to restraining residual settlement and their rapid construction. However, effect of cyclic loading has not been established although some countries suggest design methods through many studies. In this paper, cyclic loading tests were conducted to analyze dynamic load transfer characteristics of pile-supported embankment reinforced with geosynthetics. A series of 3 case full scale model tests which were non-reinforced, one-layer-reinforced, two-layer reinforced with geosynthetics were performed on piled embankments. In these series of tests, the height of embankment and pile spacing were selected according to EBGEO (2010) standard in Germany. As a result of the vertical load parts on the pile and on the geosynthetic reinforcement measured separately, cyclic loads transferred by only arching effect decreased with strength geosynthetic-reinforced case. However, final loads on the pile showed no differences among the cases. These results conflict with previous studies that reinforcement with geosynthetics increases transfer load concentrated on piles. In addition, it is observed that the load transferred to pile decreases at the beginning of cycle number due to reduction of arching effected by cyclic loading. Based on these results, transferred mechanism for cyclic load on GRPS system has been presented.

• Journal of the Korean GEO-environmental Society
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• v.21 no.9
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• pp.15-24
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• 2020

In this study, the stress concentration ratio for the improved material of the low slump mortar grouting was evaluated through the composite ground method, the ground arching theory, the plastic angle method, the 2D and 3D numerical analysis and the 3D model experiment. The stress concentration ratio calculated by the composite ground method was 89.3, 3.75~59.0 when the three-dimensional ground arching theory was applied, and 82.8 for the three-dimensional plastic angle method. As a result of the 2D numerical analysis, the stress concentration ratio was 63.0~77.0, which was found to increase as the improvement ratio increased. The results of 3D numerical analysis were predicted to be 50.0~56.0 smaller than the results of 2D analysis. In the case of a special model experiment using a large triaxial compression cell, the stress concentration ratio for each load step was 53.0~60.0, and the stress concentration ratio evaluated by the experiment was measured within 2D and 3D numerical analysis predictions. In this study, a predictive equation for the stress concentration ratio according to the improvement ratio is proposed based on the analysis and experimental values for the improved ratio of the low slump mortar grouting.

• Journal of the Korean Geotechnical Society
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• v.30 no.8
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• pp.13-24
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• 2014

A series of trapdoor model tests was systematically performed in order to investigate soil arching. The mobilized soil arching was clearly observed by change of the vertical earth pressure loaded on trapdoor of soil container box. A slow decent of the loading plate at the trapdoor results in loosening zone over the trapdoor and the stress in this loosening zone was transferred to the stationary zone in the vicinity of the trapdoor. In particular, it was observed that the vertical earth pressure rapidly decreased in the loosening zone and increased in the stationary zone at the trapdoor. Both the maximum decreasing rate of the vertical earth pressure in the loosening zone and the increasing rate of the vertical earth pressure in the stationary zone were not influenced by the ground density, but affected by the size of the trapdoor. The loosening zone could be defined by the elliptical configuration, in which the major axis was twice as long as the height of the loosening zone at the center of trapdoor and the minor axis was the same as the width of trapdoor. The height of loosening zone at the center of trapdoor was one and a half times as long as the width of trapdoor loading plate.

• Journal of the Korean Geosynthetics Society
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• v.20 no.2
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• pp.13-22
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• 2021

Pile or column supported embankments have been increasingly employed to construct highway or railway embankments over soft soils. Piles or columns of stiffer material installed in the soft ground can provide the necessary support by transferring the embankment load to a firm stratum using a soil arching. However, there has been reported to occur a relatively large differential settlement between the piles and the untreated soils. Geosynthetic reinforced pile or column supported embankment (GRPS) is often used to minimize the differential settlement. Two dimensional finite element anlyses have been performed on both the column supported embankments and the geogrid reinforced column supported embankments by using a PLAXIS 2D to evaluate the soil arching effect. Based on the results obtained from finite element analyses, the stress reduction ratio decreases as the area replacement ratio increases in the column supported embankments. For the geogrid reinforced column supported embankments, the geogrid reinforcemnt can reduce differential settlements effectively. In additon, the use of stiffer geogrid is appeared to be more effective in reducing the differential settlements.

• Journal of the Korean Geotechnical Society
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• v.39 no.11
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• pp.7-22
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• 2023

In January 2022, a new legislation was enforced to enhance the safety of underground construction. Consequently, a comprehensive assessment of underground safety is now an integral part of the planning process, including an evaluation of its impact. Ensuring the stability of temporary retaining walls during underground excavation has become paramount, prompting a heightened focus on the assessment of underground safety. This study delves into the analysis of the Multi-axis Flat Continuous Soil Cement Wall retaining wall (MFS) construction method. This method facilitates the expansion of wall thickness in the ground and provides flexibility in selecting and spacing H-piles. Through laboratory model tests, we scrutinized the load-displacement behavior of the wall, varying the H-pile installation intervals using the MFS method. Additionally, a 3-dimensional numerical analysis was conducted to explore the influence of H-pile installation intervals and sizes on the load for different thicknesses of the MFS retaining wall. The displacement analysis yielded the calculation of the height of the arching effect acting on the wall. To further our understanding, a design method was introduced, quantitatively analyzing the results of axial force and shear force acting on the wall. This involved applying the maximum arching height, calculated by the MFS method, to the existing member force review method. The axial force and shear force, contingent on the H-pile installation interval and size applied to the MFS retaining wall, demonstrated a reduction effect ranging from 24.6% to 62.9%.

• Tunnel and Underground Space
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• v.20 no.4
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• pp.260-266
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• 2010

In this study, wish to analyze effect that affect on each tunnel (right and left tunnel) according as proceeding of leading tunnel (right tunnel), following tunnel (left tunnel) and pilot tunnel excavation through behavior of tunnel and surrounding base by model tests. And stress-transfer mechanism that occurs from in-situ loosing area and arching effect by difference of stiffness ratio and overburden heights were verified experimentally. The model tests were carried out by varying the stiffness of reinforced area and overburden height, measured deformation of tunnel and displacement of surrounding base. The model tests followed exactly the real 2-Arch tunnel construction stages.