• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.3
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• pp.404-408
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• 2006

In this paper, connection strength between facing block and tie-bar was investigated through experimental study with varying in-fill material such as concrete, soil and crushed stone. Also, connection strength between anchor block and tie-bar was investigated with varying in-fill material. According to the experimental results, in case of using in-fill concrete, connection strength between facing block and tie-bar was larger than allowable tension load of tie-bar. Whereas in case of using in-fill soil or crushed stone, connection strength between facing block and tie-bar was less or similiar to allowable tension load of tie-bar. Connection strength between anchor block and tie-bar for which crushed stone was used as in-fill material, was larger than allowable tension load of tie-bar.

• Journal of the Korean Geotechnical Society
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• v.21 no.1
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• pp.51-58
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• 2005

The use of geogrid for SRW systems and bridge abutment has increased rapidly over the past 10 years in Korea. The concept of segmental retaining walls and reinforced soil is very old and for example The Ziggurats of Babylonia(i.e. Tower of Babel) were built some 2,500 to 3,000 years ago using soil reinforcing methods very similar to those described in current design. Modern SRW(Semental Retaining Wall) units were introduced in 1960's as concrete crib retaining wall systems. In this paper, the friction properties between segmental concrete units and geogrid are investigated by performing various tests.

• Journal of the Korean Geosynthetics Society
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• v.8 no.3
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• pp.45-52
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• 2009

The use of geogrid-reinforced earth wall technologies has progressed rapidly over the past 10 years in Korea because these technologies have advantages such as economical efficiency, graceful appearance, and easy construction. The geogrid used in the reinforced earth wall with concrete block facing can be subjected to damage among the upper and lower blocks and at the interface between the block and the geogrid. Therefore, when design of the geogrid-reinforced soil walls the required connection strength of the geogrid to the wall facing is an issue. In this study, new connection system between facing block and geogrid is developed to improve the damages of geogrid in the existing connection systems. The new connection devices are made of steel and have I-shape. This paper describes the test method and results of the laboratory testing for determination of connection strength in connection system using the I-type connection device.

• Journal of the Korean Geotechnical Society
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• v.25 no.2
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• pp.5-15
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• 2009

The conventional reinforced earth retaining wall has the connector system to fix the reinforcement and block. However, this system defect may cause the crack of block and the rupture of reinforcement due to the stress concentration near the face of reinforced earth retaining wall. Hence, the new connector system which was able to allow the settlement of reinforcement was developed in this study and a test was carried out in the study area which is divided into the conventional reinforced earth retaining wall and reinforced Earth Retaining Wall driving the settlement. As the results of field monitoring in situ, the ratio of tensile force calculated at maximum value on contiguous portion of front block showed that the settlement type decreased the stress concentration near the face of front block greater than the conventional type.

• Journal of the Korean GEO-environmental Society
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• v.14 no.12
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• pp.53-60
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• 2013

A new type of reinforced earth wall(REW) system is developed with vegetated facing which provides proper environment for long-term vegetation and also applicable to high retaining wall system. Vegetated retaining wall is a green alternative for retaining walls and an effective way to reduce heat island effect than conventional block or concrete systems. Several construction sites using vegetated facing is observed to monitor adaptation state of vegetation and estimate surface temperature of wall facing over two years. It was observed that a number of plants including Siberian chrysanthemum adapt well to the inside of the facing blocks because vegetation bag helps to keep a proper condition for vegetation. According to the results using thermographic camera, average surface temperature of vegetated facing is higher for all ranges of coverage ratio of vegetation. The increment of average surface temperature of vegetated facing is larger than that of non-vegetated facing when the air temperature rises, and vice versa.

• Journal of the Korean Geosynthetics Society
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• v.8 no.2
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• pp.21-29
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• 2009

The connection strength between wall facing and geosynthetics should be evaluated by experimental method in the design of reinforced earth wall. However, the evaluation result of connection strength using the typical design method, FHWA(1996) and NCMA(1997), is excessively because of a safety factors. Therefore, this study is conducted in connection strength test between wall facing and geosynthetics, then the test result is applied to the design case by NCMA, FHWA and Soong & Koener(1997). The results confirmed that the evaluation method by Soong & Koener, which is used ultimate connection strength by connection strength test in allowable connection strength, is satisfied with stable in design.

• Journal of the Korean Geotechnical Society
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• v.20 no.1
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• pp.83-90
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• 2004

Retaining walls with reinforced earth have been constructed around the world. The use of reinforced earth is a recent development in the design and construction of earth-retaining structure. It is believed that reinforced retaining wall has some advantages which make construction quite simple basically. It wilt take short construction time relatively, comparing, fur example with reinforced-concrete retaining wall. In addition, low price and easy construction will be good attractive points in practical point of view. In this study, five field-tests monitoring data for lateral pressures on geogrid-reinforced retaining wall have been compiled and evaluated. Based on field-tests it is found that horizontal displacements of the facing was measured to be about 0.19∼0.76% and that the maximum tensile strains of reinforcement was evaluated to be about 0.66∼1.98%. The maximum tensile strains, measured from each site, do not reach 5% of the practical allowable strain of the geogrid. And also it is found that the lateral pressure distributions of reinforced-earth retaining wall are close to a trapezoid shape like a flexible retaining wall system, instead of a theoretical triangular shape.

• Journal of Radiation Protection and Research
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• v.39 no.1
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• pp.21-29
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• 2014

A new cold neutron triple-axis spectrometer (Cold-TAS) was recently constructed at the 30 MWth research reactor, HANARO. The spectrometer, which is composed of neutron optical components and radiation shield, required a redesign of the segmented monochromator shield due to the lack of adequate support of its weight. To shed some weight, lowering the height of the segmented shield was suggested while adding more radiation shield to the top cover of the monochromator chamber. To investigate the radiological effect of such change, we performed MCNPX simulations of a few different configurations of the Cold-TAS monochromator shield and obtained neutron and photon intensities at 5 reference points just outside the shield. Reducing the 35% of the height of the segmented shield and locating lead 10 cm from the bottom of the top cover made of polyethylene was shown to perform just as well as the original configuration as radiation shield excepting gamma flux at two points. Using gamma map by MCNPX, it was checked that is distribution of gamma. Increased flux had direction to the top and it had longer distance from top of segmented shield. However, because of reducing the 35% of the height, height of dissipated gamma was lower than original geometry. Reducing the 35% of the height of the segmented shield and locating lead 10cm from the bottom of the top cover was selected. After changing geometry, radiation dose was measured by TLD for confirming tester's safety at any condition. Neutron(0.21 ${\mu}Svhr^{-1}$) and gamma(3.69 ${\mu}Svhr^{-1}$) radiation dose were satisfied standard(6.25 ${\mu}Svhr^{-1}$).

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.2C
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• pp.75-82
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• 2011

Recently, a new reinforced retaining wall with light steel support face has been developed. In this study, full size in-situ test is carried out to investigate the stability of the new reinforced retaining wall. The lateral displacement of wall, lateral earth pressure, and settlement of the reinforced retaining wall are measured in the full size test. And numerical analysis by 3-D finite element method is also carried out to compare the test results with those of the analysis. From the full size in-situ test, the maximum lateral displacement of wall is 46mm(0.009H) and the maximum settlement is 21.5mm. And comparing these values with those of numerical analysis, it is confirmed that the new reinforced retaining wall with light steel support face is stable and applicable.

• Journal of the Korean Geotechnical Society
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• v.20 no.7
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• pp.119-126
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• 2004

A small-scale reinforced earth wall was constructed in a laboratory to investigate the effect of wall rigidity and of construction sequence on the wall. A full continuous wall facing and a discrete wall facing were designed and constructed for tests. These two different facing systems should adapt different construction procedures due to their different facing shapes. The model wall was built with geo-grid reinforcement, sand, and facings on rigid surface. The model wall was instrumented with earth pressure gages, LVDTs, and strain gages. The experimental results have shown differences in wall behavior related to construction sequence and types of wall facing. It is found in this study that the reinforced earth wall built with full continuous facing is safer than the reinforced earth wall built with the discrete wall facing.