• Geomechanics and Engineering
• /
• v.13 no.1
• /
• pp.43-61
• /
• 2017

The inverted T-type abutments are generally used in highway bridges constructed in Korea. This type of abutment is used because it has greater stability, with more pile foundations embedded in the bedrock, while simultaneously providing support for lateral earth pressure and vertical loads of superstructures. However, the cross section of inverted T-type abutments is large compared with the piers, which makes them more expensive. In addition, a differential settlement between the abutment and embankment, as well as the expansion joints, causes driving discomfort. This study evaluated the driving comfort of several types of abutments to improve driving comfort on the abutment. To achieve this objective, a traditional T-type abutment and three types of candidate abutments, namely, mechanically stabilized earth wall (MSEW) abutment supported by a shallow foundation (called "true MSEW abutment"), MSEW abutment supported by piles (called "mixed MSEW abutment"), and pile bent and integral abutment with MSEW (called "MIP abutment"), were selected to consider their design and economic feasibility. Finite element analysis was performed using the design section of the candidate abutments. Subsequently, the settlements of each candidate abutment, approach slabs, and paved surfaces of the bridges were reviewed. Finally, the driving comfort on each candidate abutment was evaluated using a vehicle dynamic simulation. The true MSEW abutment demonstrated the most excellent driving comfort. However, this abutment can cause problems with respect to serviceability and maintenance due to excessive settlements. After our overall review, we determined that the mixed MSEW and the MIP abutments are the most appropriate abutment types to improve driving comfort by taking the highway conditions in Korea into consideration.

• Journal of the Korean GEO-environmental Society
• /
• v.9 no.2
• /
• pp.47-59
• /
• 2008

Application of mechanically stabilized earth wall (MSEW) abutment has been rapidly increasing in United States of America, Pennsylvania since 2002. MSEW is effective for reducing construction cost and period compared to general concrete reinforced wall. In the paper, theoretical background and conventional criterion of MSEW abutment that is widely used abroad are analyzed. Based on the results, application of suitable MSEW abutment to domestic bridge type is examined. For the application of MSEW abutment in Korea, load interacting with upper shoe in domestic bridge types and structural analyses of beam seat and pile are investigated. As a result, all applications are possible except for PSC BOX Bridge that has heavy self-weight of girder. Through two and three dimensional numerical analyses, horizontal behaviour mechanisms between pile and MSEW were analyzed and field tests are also carried out for seven piles behind earth walls. From results of field tests, it is confirmed that an angle of internal friction of backfill material needs to be greater than 34 degree to use H-Pile as foundation of MSEW.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.5
• /
• pp.263-274
• /
• 2018

In this study, the applicability and external/internal stability of a MSEW abutment with a slab were investigated. Structural analysis of slab bridges between 10 ~ 20.0 m and thicknesses of 0.7 ~ 0.9 m was carried out to calculate the reaction forces due to dead and live loads acting on the bridge supports. The slab bridge with a length of 20.0 m satisfied the allowable contact pressure of 200 kPa for the true MSEW abutment. Because the external stability of the true MSEW abutment was dominated by the geometry of the MSE wall, the change in the factor of safety due to the load of the super-structure is small. Because the stiffness of the foundations is fixed and the load of the super-structure is increased, the factor of safety of the bearing capacity was reduced. As the load of the super-structure was increased, the horizontal earth pressure of the true MSEW abutment increased greatly. As a result, the pullout and fracture of the uppermost reinforcement, which are the factors of safety, did not meet the design criteria. Therefore, it is necessary to increase the pullout resistance and the long-term allowable tensile force of the reinforcement placed on the top of the reinforced soils to ensure efficient design and performance of a true MSEW abutment.

• 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.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.5
• /
• pp.399-409
• /
• 2018

The mechanically stabilized earth wall (MSEW) of the IPM bridge is an important structure that constitutes the bridge, and supports the horizontal earth pressure and approach slab. Therefore, it is necessary to carefully analyze the settlement of MSEW of the IPM bridge. This study examined the settlement according to the height and ground stiffness on the MSEW on the IPM Bridge. According to the design guideline, the IPM Bridge (2016) was designed to have a height of 4.0 ~ 10.0m and the elastic settlement was calculated. The base area and the grounding pressure of the MSE wall increased linearly with the height, and the elastic settlement also increased linearly. In addition, the stiffness of the foundations satisfying the allowable settlement of the approach slab is a N value of 35 or more. The settlement of finite element analysis was estimated to be smaller than the elastic settlement, and the stiffness of the foundation ground satisfied the allowable settlement of the approach slab above N value of 20. Because the elastic settlement of the MSEW of the IPM Bridge was overestimated, it will be necessary to examine it carefully by finite element analysis.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.5
• /
• pp.510-519
• /
• 2019

In this study, the structural analysis was conducted to the comparison of reaction force and contact pressure on the design truck load (DB-24 and KL-510) of slab bridge supported by MSEW abutment. As a result of the structural analysis, the reaction force acting on the abutment at the continuous bridge was reduced rather than the simple span bridge. The reaction force due to the dead load was estimated to be about twice as large as that of the live load, and the influence of the live load on the total reaction force was relatively small. The contact pressure of the MSEW abutment was estimated to be the largest in the simple span bridge. The influence of contact pressure on the type of live load was relatively small. Therefore, it is considered to be more advantageous to apply the MSEW abutment to the continuous bridge than to the simple span bridge because the contact pressure acting on the abutment on the continuous bridge is estimated to be small. Since the reaction force and the load sharing ratio acting on the MSEW abutment depending on various conditions, it is necessary to examine the contact pressure in various types of bridges and specifications.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.52 no.3
• /
• pp.113-120
• /
• 2010

Reduction factor for installation damage required to calculate design strength of geogrid used in MSEW(mechanically stabilized earth wall) design is usually obtained in the field test simulating real construction condition. However, damages occurred in geogrid during backfill work are influenced by many factors such as polymer types, unit weight per area, backfill construction method and gradation of backfill material and field test considering these factors demand lots of time and costs. In this study, factors affecting installation damage are analyzed and empirical method to evaluate reduction factor for installation damage using maximum particle size in backfill material is suggested.

• Journal of the Korean Geosynthetics Society
• /
• v.12 no.1
• /
• pp.101-107
• /
• 2013

Environmental-friendly and economical construction are the recent issues for civil structures and soilbag as facing wall is widely used for cut-slope remediation projects. However, the stability of structures is an important issue for the use of environmental-friendly and economical materials. In order to understand the stability of soilbag reinforced retaining wall, tensile resistance, rupture, tensile strength, and internal/external safety factor of the wall were analyzed with MSEW program and the results were compared to the safety factor of block-type reinforced walls. The stability of retaining wall was analyzed with reduction coefficients of connection strength to check the connection stability. Because it is possible to move between soilbag and geogrid connector for soilbag retaining wall, the safety factor of the wall was analyzed with different inclination angles of soilbag. The analysis result shows that the connection strength and internal/external stability of soilbag reinforced wall satisfy the stability criteria.

• Journal of the Korean Geosynthetics Society
• /
• v.6 no.4
• /
• pp.29-37
• /
• 2007

Reduction Factor for Installation Damage required for calculation of design strength of geogrid used in MSEW(mechanically stabilized earth wall) design is usually obtained in the field test simulating real construction condition. However, damages occurred in geogrid during backfill work are influenced by many factors such as polymer types, unit weight per area, backfill construction method and gradation of backfill material and field test considering these factors demands lots of time and costs. In this study, factors affecting installation damage are analyzed and empirical method for evaluating reduction factor for installation damage using maximum particle size in backfill material is suggested.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.3
• /
• pp.594-601
• /
• 2019

A true MSEW abutment is an abutment type that directly supports the load of a superstructure. Metal strips, which are in-extensile reinforcements, should be used to minimize abutment deformation. A study to derive the application conditions of a True MSEW abutment was carried out by Zevogolis(2007). As a result, the pullout factor of safety of the uppermost reinforcement was estimated to be the smallest. Therefore, the pullout factor of safety of the uppermost reinforcement is the most important design factor. Parameter analysis was conducted with the abutment length, abutment heel, and abutment height as variables. The pullout factor of safety increased with increasing abutment length and abutment heel length. This is because the contact area increases and the superstructure is dispersed as the abutment length and abutment heel length increase. The pullout factor of safety converges at an abutment length of 1.2m and an abutment heel length of 0.9m. This is because the effective length of the reinforcement is reduced due to the increase in contact area. On the other hand, the extension of the superstructure will increase if the abutment length and abutment heel length are increased excessively. In addition, earth-volume is increased if the abutment height increases excessively. This acts as an upper load on the MSE wall. Therefore, it needs to be examined carefully.