• Geomechanics and Engineering
• /
• v.36 no.3
• /
• pp.277-293
• /
• 2024

Shored Mechanically Stabilized Earth (SMSE) walls are types of soil retaining structures that increase soil stability under static and dynamic loads. The damage caused by an earthquake can be determined by evaluating the probabilistic seismic response of SMSE walls. This study aimed to assess the seismic performance of SMSE walls and provide fragility curves for evaluating failure levels. The generated fragility curves can help to improve the seismic performance of these walls through assessing and controlling variables like backfill surface settlement, lateral deformation of facing, and permanent relocation of the wall. A parametric study was performed based on a non-linear elastoplastic constitutive model known as the hardening soil model with small-strain stiffness, HSsmall. The analyses were conducted using PLAXIS 2D, a Finite Element Method (FEM) program, under plane-strain conditions to study the effect of the number of geogrid layers and the axial stiffness of geogrids on the performance of SMSE walls. In this study, three areas of damage (minor, moderate, and severe) were observed and, in all cases, the wall has not completely entered the stage of destruction. For the base model (Model A), at the highest ground acceleration coefficient (1 g), in the moderate damage state, the fragility probability was 76%. These values were 62%, and 54%, respectively, by increasing the number of geogrids (Model B) and increasing the geogrid stiffness (Model C). Meanwhile, the fragility values were 99%, 98%, and 97%, respectively in the case of minor damage. Notably, the probability of complete destruction was zero percent in all models.

• Geomechanics and Engineering
• /
• v.36 no.4
• /
• pp.329-341
• /
• 2024

Retaining structures are one of the most important elements in the stabilization of excavations and slopes in various engineering projects. Mechanically stabilized earth (MSE) walls are widely used as retaining structures due to their flexibility, easy and economical construction. These benefits are especially prominent for projects built on soft and weak foundation soils, which have relatively low resistance and high compressibility. For high retaining walls on weak foundations, conventional design methods are not cost-effective. Therefore, two alternative solutions for different foundation weakness are proposed in this research: optimized multi-tiered MSE walls and single tier wall with foundation improvement. The cost optimization considers both the construction components and the land price. The results show that the optimal solution depends on several factors, including the foundation strength and more importantly, the land price. For low land price, the optimized multi-tiered wall is more economical, while for high land price (urban areas), the foundation improvement is preferable. As the foundation strength decreases, the foundation improvement becomes inevitable.

• Journal of the Korean Geotechnical Society
• /
• v.36 no.12
• /
• pp.69-76
• /
• 2020

Since the mechanically stabilized earth walls have a form of retaining wall compatible with a narrow section, the geogrid overlaps according to the separation distance between the walls. There is a problem that the overall behavior may occur in the state of being integrated with the stress change due to the interaction of the geogrid. Therefore, a careful approach is required at the design stage, but there are currently no design criteria or guidelines in Korea. This study investigated the optimal reinforcement length ratio according to the retaining wall width to height ratio (width to height ratio, Wb/H) for these back-to-back mechanically stabilized earth walls. Retaining wall width ratio is 1.1H, 1.4H, 1.7H, 2.0H for Case II of the FHWA design standard, and the height is 3.0 m, 5.0 m, 7.0 m, and 10.0 m, which are most commonly applied. Through numerical analysis, the appropriateness of the FHWA design standard and the optimal reinforcement length ratio according to the height of the retaining wall and the width of the retaining wall were proposed.

• Geomechanics and Engineering
• /
• v.1 no.3
• /
• pp.193-204
• /
• 2009

A 10.4-m high highway embankment retained behind mechanically stabilized earth (MSE) walls is under construction in the northeastern part of the Indian state of Bihar. The structure is constructed with compacted, micaceous, grey, silty sand, reinforced with polyester (PET) geogrids, and faced with reinforced cement concrete fascia panels. The connections between the fascia panels and the geogrids failed on several occasions during the monsoon seasons of 2007 and 2008 following episodes of heavy rainfall, when the embankment was still under construction. However, during these incidents the MSE embankment itself remained by and large stable and the collateral damages were minimal. The observational data during these incidents presented an opportunity to develop and calibrate a simple procedure for estimating rainfall induced pore water pressure development within MSE embankments constructed with backfill materials that do not allow unimpeded seepage. A simple analytical finite element model was developed for the purpose. The modeling results were found to agree with the observational and meteorological records from the site. These results also indicated that the threshold rainwater infiltration flux needed for the development of pore water pressure within an MSE embankment is a monotonically increasing function of the hydraulic conductivity of backfill. Specifically for the MSE embankment upon which this study is based, the analytical results indicated that the instabilities could have been avoided by having in place a chimney drain immediately behind the fascia panels.

• 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.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1999.10a
• /
• pp.473-480
• /
• 1999

This paper presents the results of a parametric study on the behavior of mechanically stabilized earth retaining wall. It has been recognized that the currently available design guidelines, which is base on the limit equilibrium approach, cannot properly account the interaction effect between the components, construction sequence, and foundation settlement which may impose a significant influence on the wall behavior. A parametric study using finite element analysis was performed to investigate the behavior of MSE wall under different construction conditions and the applicability of the current design approach. In the parametric analysis, the effects of the construction sequence, the surcharge, and the foundation stiffness were studied and a detailed finite element modeling for various components of the system were employed. The results, such as wall displacement and earth pressure distributions, reinforcement forces, vertical stress distribution were then thoroughly analyzed to investigate the effect of construction details on the wall behavior.

• Geomechanics and Engineering
• /
• v.31 no.6
• /
• pp.599-614
• /
• 2022

One of the methods of stabilizing retaining walls, embankments, and deep excavations is the implementation of plate anchors (like the Geolock wall anchor systems). Back-to-back Mechanically Stabilized Earth (BBMSE) walls are common stabilized earth structures that can be used for bridge ramps. But so far, the analysis of the interactive behavior of two back-to-back anchored walls (BBAW) by double-plates anchors (constructed closely from each other and subjected to the limited-breadth vertical loading) including interference of their failure and sliding surfaces has not been the subject of comprehensive studies. Indeed, in this compound system, the interaction of sliding wedges of these two back-to-back walls considering the shear failure wedge of the foundation, significantly impresses on the foundation bearing capacity, adjacent walls displacements and deformations, and their stability. In this study, the effect of horizontal distance between two walls (W), breadth of loading plate (B), and position of vertical loading was investigated experimentally. In addition, the comparison of using single and equivalent double-plate anchors was evaluated. The loading plate bearing capacity and displacements, and deformations of BBAW were measured and the results are presented. To evaluate the shape, form, and how the critical failure surfaces of the soil behind the walls and beneath the foundation intersect with one another, the Particle Image Velocimetry (PIV) technique was applied. The experimental tests results showed that in this composite system (two adjacent-loaded BBAW) the effective distance of walls is about W = 2.5*H (H: height of walls) and the foundation effective breadth is about B = H, concerning foundation bearing capacity, walls horizontal displacements and their deformations. For more amounts of W and B, the foundation and walls can be designed and analyzed individually. Besides, in this compound system, the foundation bearing capacity is an exponential function of the System Geometry Variable (SGV) whereas walls displacements are a quadratic function of it. Finally, as an important achievement, doubling the plates of anchors can facilitate using concrete walls, which have limitations in tolerating curvature.

• Journal of the Korean Geotechnical Society
• /
• v.40 no.2
• /
• pp.81-93
• /
• 2024

In Korea, numerous large-scale infrastructure construction projects and housing site developments are being undertaken. However, due to limited land availability, sourcing high-quality backfill materials that meet the standards for railroad and road embankment compaction and mechanically stabilized earth (MSE) retaining wall construction poses significant challenges. Concurrently, there has been an increase in structural failures of many MSE retaining walls, attributed primarily to reduced bearing capacity and impaired drainage performance, resulting from inadequate backfill compaction. This study aimed to analyze the structural performance and safety of an MSE retaining wall using recycled soil as backfill. We conducted small-scale model tests utilizing 3D printing technology combined with two-dimensional numerical analysis. The study quantitatively evaluated the MSE retaining wall's performance concerning the recycled soil mixing ratio and reinforcement installation methods. Furthermore, the utility of 3D printing was confirmed through the production of an experimental wall designed to facilitate easy reinforcement attachment, mirroring the conditions of actual MSE retaining wall construction.

• Geomechanics and Engineering
• /
• v.15 no.4
• /
• pp.937-945
• /
• 2018

A probabilistic study of a reinforced earth wall in a frictional soil using the surface response methodology (RSM) is presented. A deterministic model based on numerical simulations is used (Abdelouhab et al. 2011, 2012b) and the serviceability limit state (SLS) is considered in the analysis. The model computes the maximum horizontal displacement of the wall. The response surface methodology is utilized for the assessment of the Hasofer-Lind reliability index and is optimized by the use of a genetic algorithm. The soil friction angle and the unit weight are considered as random variables while studying the SLS. The assumption of non-normal distribution for the random variables has an important effect on the reliability index for the practical range of values of the wall horizontal displacement.

• Journal of the Korean Geosynthetics Society
• /
• v.16 no.4
• /
• pp.83-92
• /
• 2017

This paper deals with numerical analysis of behavior of curved mechanically stabilized earth(MSE) walls with geosynthetics reinforcement. Unlike typical concrete retaining walls, MSE wall enables securing stability of higher walls without being constrained by backfill height and is currently and widely used to create spaces for industrial and residential complexes. The design of MSE walls is carried out by checking external stability, similarly to the external checks of conventional retaining wall. In addition, internal stability check is mandatory. Typical stability check based on numerical analysis is done assuming 2-dimensional condition (plane strain condition). However, according to the former studies of 3-dimensional MSE wall, the most weakest part of a curved geosynthetic MSE wall is reported as the convex location, which is also identified from the studies of the laboratory model tests and field monitoring. In order to understand the behaviour of the convex location of the MSE wall, 2-dimensional analysis clearly reveals its limitation. Furthermore, laboratory model tests and field monitoring also have restriction in recognizing their behaviour and failure mechanism. In this study, 3-dimensional numerical analysis was performed to figure out the behaviour of the curved part of the geosynthetic reinforced wall, and the results of the straight-line and curved part in the numerical analysis were compared and analysed. In addition, the behaviour characteristics at each condition were compared by considering the overburden load and relative density of backfill.