• Journal of the Korean Geosynthetics Society
• /
• v.4 no.1
• /
• pp.17-25
• /
• 2005

This paper presents a case history of a geosynthetics-reinforced segmental retaining wall, which collapsed during a sever rainfall immediately after the completion of the wall construction. In an attempt to identify possible causes for the collapse, a comprehensive investigation was carried out including physical and strength tests on the backfill, stability analyses on the as-built design based on the current design approaches, and slope stability analyses with pore pressure consideration. The investigation revealed that the inappropriate as-built design and the bad-quality backfill were mainly responsible for the collapse. This paper describes the site condition including wall design, details of the results of investigation and finally, lessons learned. Practical significance of the findings from this study is also discussed.

• Journal of the Korean Geosynthetics Society
• /
• v.3 no.4
• /
• pp.13-19
• /
• 2004

This paper presents the results of an investigation on the failure mechanism of geosynthetic-reinforced segmental retaining walls in tiered arrangement using reduced-scale model tests. In this laboratory model tests, a reduced scale model of the full-scale geosynthetic-reinforced wall which was constructed in Geotechnical Experimental Site at Sungkyunkwan University was used to perform a study on the failure mechanism. In order to a high degree of realism, the geometry of the wall and the material properties were selected applying Similitude Laws was used to perform laboratory model tests. And contrary to the previous failure tests with various surcharge pressures, the failure by the tired wall weight was observed. Primary variables considered in the model tests include the different offset distance between the tiers and the different reinforcement length in the lower tier and as a result of the parametric study, a different failure pattern was observed.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2001.10a
• /
• pp.337-344
• /
• 2001

The application of mechanically stabilized earth wall(MSEW) with segmental front panel has been increasing in highway construction due to its cost-effectiveness. However, some failures during construction have been reported and many field engineers are reluctant to select this method for important structure. One of the main reasons may be that there is no moderate specification for design and construction of MSEW yet. This paper discussed the main results of analysis on a case of block-type segmental retaining wall in highway construction. Based on the results, some recommendations on design and construction method of MSEW are presented.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2000.09a
• /
• pp.41-50
• /
• 2000

Segmental retaining wall market in Korea has been growing dramatically since late 1990s in both engineered and non-engineered applications. Despite the inherent conservatism in the current design approaches, numerous major and minor structural problems have been reported during and after construction, covering a range of minor structural damage to total collapse. Much still needs to be investigated to fill the gap between the theory and the practice. This paper reviews several design issues with regard to the segmental retaining walls such as the selection of shear strength parameters for backfill soil, local stability, and tiered wall construction. In addition, the effects of shear strength parameters and the fundamental behavior of tiered SRWs are examined based on the results of finite element analysis. Implications of the findings from this study to current design practices were discussed in detail.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.10a
• /
• pp.168-175
• /
• 2008

The method of reinforced earth walls has grown remarkably and the frequency of utilization has been increased on a national scale thereafter introduced in the middle 1980s in Korea. Furthermore the construction case of the extensive Geosynthetic-Reinforced Segmental Retaining Walls had been increased. Currently, the design criterion of FHWA and NCMA mainly used in Korea suggest determining the horizontal distance of the upper/lower retaining wall based on the study results of the internal stability and the external stability of Segmental Retaining Walls but in many cases are not suitable for the actual situation in Korea. Therefore, in this study reviewed the design criterion of Geosynthetic-Reinforced Segmental Retaining Walls, performed the internal and external stability in Paju, Gyeonggi-do based on the design criterion of FHWA and NCMA, suggested the modified design criterion of FHWA with analyzing the results, and performed the stability analysis for the internal and external stability and the compound failure. Moreover for the confirmation of the modified FHWA design standard, the suggestion and the analysis of the numerical analysis approaching method using shear strength reduction technique were performed and the design cases utilized the modified FHWA design standard based on the study analysis were introduced.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1999.11c
• /
• pp.69-83
• /
• 1999

Soil-reinforced segmental retaining walls(SRW) have been proven to be high earthquake-resistant structure during recent earthquakes in United States and Japan. The mechanicals behavior of the SRWs under seismic loading, however, has not been fully understood. Although the seismic design issues for the civil engineering structures have gained much attention in Korea due to the increase in frequency of earthquake occurrence, the seismic design for the SRWs has not been being implemented. This study has been undertaken with the aim of developing a more rational seismic design/analysis method for soil-reinforced segmental retaining walls. This paper present fundamentals of current seismic design/analysis method and the results of a comparative study between NCMA and FHWA design guidelines, Practical implications of the findings from this study are discussed in great detail.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2006.03a
• /
• pp.1038-1045
• /
• 2006

The Green Wall is highest eco-system among a segmental retaining wall systems. Recently, the demand of high segmental retaining wall (SRW) is increased in domestic. The soil nailing system is applied in order to maintain the high SRW stability for steeper slope. However, the proper design approach that can consider the earth pressure reduction effects in soil nailing system has not been proposed. This study was performed to introduce the design case by 'Two-Body Translation mechanism' to be able to consider distribution of earth pressure in the soil nailing when designing the green wall using soil nailing system. Also, this study attempts to evaluate the earth pressure change when advanced soil nailing system is constructed using $FLAC^{2D}$ ver. 3.30 program and 'Two-Body Translation mechanism'. Also in this study, various parametric studies using numerical methods as shear strength reduction (SSR) technique and limit equilibrium technique were carried out. In the parametric study, the length ratio and the bond ratio of the soil nailing were changed to identify the earth pressure reduction effect of the retaining wall reinforced by soil nailing.

• Journal of the Korean GEO-environmental Society
• /
• v.7 no.5
• /
• pp.41-48
• /
• 2006

Crib wall is one of the segmental grid retaining walls using headers and stretchers to establish the framework of the wall. In this method, grids formed by the intersection of headers and stretchers are generally filled with the gravel to maintain the weight of the wall. Therefore, the construction can be carried out with higher speed and much economically when compared with the concrete retaining wall. Furthermore, it has high drain capacity, and environmentally friendly aspects also have been pointed out because the possibility of the planting at the front of the wall. However, in the crib wall method, the relative movement between the individual headers and stretchers was generally recognized, and stress redistribution in the gravel filling was also observed when subjected to the external loading and self-weight of filling. Therefore, it has been thought that the distribution of the earth pressure in the crib wall system differ from that of the concrete retaining wall. In this study, the surcharge tests using the scaled model crib wall was carried out to observe the distribution of the earth pressure in the segmental grid retaining wall. The earth pressure was measured in the six specified height of wall, and the distribution of the pressure was analyzed. Furthermore, the earth pressure by computation or by the test using the concrete retaining wall was also considered to make comparison.

• Journal of the Korean Society for Railway
• /
• v.15 no.5
• /
• pp.467-475
• /
• 2012

Static and dynamic train load tests were conducted to evaluate the train load transfer mechanism in the roadbed which was retained by two types (fully and partially) of segmental retaining walls reinforced by geogrid. The test roadbed was 2.6m high, 5m wide, and 6m long. A combination of earth pressure gages, displacement transducers, and strain gages were placed in specific locations to measure the responses. Test results showed that the wall displacement pattern as well as the earth pressure for the fully reinforced retaining wall was different from those for the partially reinforced retaining wall. In the dynamic train load test, the strain in the upper part of the wall tended to decrease, and both the residual deformation and the rate of the deformation were significantly lower than those in the current design standard.

• Journal of the Korean Geosynthetics Society
• /
• v.3 no.1
• /
• pp.27-36
• /
• 2004

This paper presents the results of stability analyses on soil-reinforced segmental retaining walls in a tiered arrangement. Four different walls were examined to investigate the appropriateness of their designs within the context of the current design guidelines based on limit equilibrium. Slope stability analysis against the compound failure mode, which is frequently ignored during design, was also performed based on the method recommended by FHWA design guidelines. Also presented are the results of instrumentation on a full-scale field trial wall constructed as part of this study. The implications of the findings from this study are discussed.