• KSCE Journal of Civil and Environmental Engineering Research
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• v.3 no.3
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• pp.71-86
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• 1983

Current R.C. retaining wall design is bared on WSD, but the reliability based design method is more rational than the WSD. For this reason, this study proposes a reliability based design criteria for the cantilever retaining wall, which is most common type of retaining wall, and also proposes the theoretical bases of nominal safety factors of stability analysis by introducing the reliability theory. The limit state equations of stability analysis and design of each part of cantilever retaining wall are derived and the uncertainty measuring algorithms of each equation are also derived by MFOSM using Coulomb's coefficient of the active earth pressure and Hansen's bearing capacity formula. The levels of uncertainties corresponding to these algorithms are proposed appropriate values considering our actuality. The target reliability indices (overturning: ${\beta}_0$=4.0, sliding: ${\beta}_0$=3.5, bearing capacity: [${\beta}_0$=3.0, design for flexure: [${\beta}_0$=3.0, design for shear: ${\beta}_0$=3.2) are selected as optimal values considering our practice based on the calibration with the current R.C. retaining wall design safety provisions. Load and resistance factors are measured by using the proposed uncertainties and the selected target reliability indices. Furthermore, a set of nominal safety factors, allowable stresses, and allowable shear stresses are proposed for the current WSD design provisions. It may be asserted that the proposed LRFD reliability based design criteria for the R.C. retaining wall may have to be incorporated into the current R.C. design codes as a design provision corresponding to the USD provisions of the current R.C. design code.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.83-97
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• 2000

In the present study, artificial neural network based on the multi-layer perceptron is used and an optimum model is chosen through the process of efficiency evaluation in order to develop a system predicting maximum displacements of the earth retaining walls at various excavation stages. By analyzing the measured field data collected at various urban excavation sites in Korea, factors influencing on the behaviors of the excavation wall are examined. Among the measured data collected, reliable data are further selected on the basis of the performance ratio and are used as a data base. Data-based measurements are also utilized for both teaming and verifying the artificial neural network model. The learning is carried out by using the back-propagation algorithm based on the steepest descent method. Finally, to verify a validity of the formulated artificial neural network system, both the magnitude and the occurring position of the maximum horizontal displacement are predicted and compared with measured data at real excavation sites not included in the teaming process.

• Journal of the Korean Geotechnical Society
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• v.32 no.12
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• pp.45-57
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• 2016

The Inclined Earth Retaining Structure (IER) is the structure using an integrated system of both front supports and inclined back supports to increase the stability for excavation. The IER is a structurally stable temporary excavation method using the back supports restraining the lateral displacement of the front supports as stabilizing piles. The back supports connected to the front supports significantly reduce the earth pressure acting on both the front wall and the front supports by distributing it to the back supports in order to increase the structural stability. In this study, mechanical behaviors of IER according to the head connection type using fixed- or hinge-connection were found by performing numerical analysis and laboratory model tests in the sandy ground. The maximum lateral displacement of fixed-connection was 88% of that of hinge-connection in the numerical analysis. The lateral displacement of fixed-connection was 7% of that of hinge-connection in the laboratory model test results. Furthermore, the earth pressure of the fixed-connection was 67% of that of the hinge-connection in the shear-strain analysis results of the model ground.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.235-244
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• 1993

The present study was made based on the zero extension line theory and the well-known Mononobe-Okabe's to determine the dynamic earth pressures acting on the retaining walls. The zero extension line theory, which was proposed by Roscoe et al., assumes the coincidence between the loci of failure and the zero extension lines in soil mass. ln order to compute the dynamic earth pressure developed by an earthquake, it was assumed that for the vertical retaining walls with no surcharge, the backfill materials are dense and cohesionless sandy soils, there are no changes in soil parameters during earthquake, and the horizontal earthquake intensity is considered. The effects of horizontal earthquake intensity, internal friction angle of soil, wall friction angle and dilation angle, on the earth pressure coefficients were analysed. Final1y, the presented theories were successfully compared with the Mononobe-Okabe's as well.

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

• The Journal of the Convergence on Culture Technology
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• v.8 no.5
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• pp.469-475
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• 2022

As the recent structure construction is constructed as a large-scale and deep underground excavation in close proximity to the building, the installation of retaining wall and supporters (Struts) has become complicated, and the number of supporters to avoid interference of the structural slab has increased. This construction process becomes a factor that causes an increase in construction joints of a structure, leakage and an increase in wall cracks. In addition, this reduced the durability and workability of the structure and led to an increase in the construction period. This study planned to dismantle the two struts simultaneously as a plan to reduce the construction joints, and corrected the earth pressure by assuming the reaction force value by the initial earth pressure and the measured data as the response ratio. After recalculating the corrected earth pressure through the iterative trial method, it was verified by numerical analysis that simultaneous disassembly of the two struts was possible. As a result of numerical analysis applying the final corrected earth pressure, the measured value for the design reaction force was found to be up to 197%. It was analyzed that this was due to the effect of grouting on the ground and some underestimation of the ground characteristics during design. Based on the result of calculating the corrected earth pressure in consideration of the response ratio performed in this study, it was proved analytically that the improvement of the brace dismantling process is possible. In addition, it was considered that the overall construction period could be shortened by reducing cracks due to leakage and improving workability by reducing construction joints. However, to apply the proposed method of this study, it is judged that sufficient estimations are necessary as there are differences in ground conditions, temporary facilities, and reinforcement methods for each site.

• Geotechnical Engineering
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• v.12 no.4
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• pp.47-60
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• 1996

Of the classical theories on lateral earth pressure, the Coulomb's and the Rankine's theories, which have been usually used in practice for design of retaining walls, assumed that the lateral earth pressure was a triangular distribution. However, the experimental results obtained by Terzaghi(1934), Tsagreli(1967), Fang & Ishibashi(1986), etc showed that lateral pressure were not triangular distribution. ' In this study, for rigid walls with inclined backfaces and inclined surfaces backfilled by $C-\phi$ soils, an analytical method of earth pressure distribution has been newly suggested by using the concept of the flat arch. The results calculated by the newly suggested equations were compared with ones by the existed theories. And'the influence factors of the earth pressures by the suggested equations were investigated. As a result, the thrusts obtained by this method agree well with those by the existing theories, except the Rankine's solution. It was showed that the height to the centre of pressure(h) depends mainly upon the inclinations of the backface and the backfilled surface, the angle of internal friction, and the adhesion between the wall and the backfilled soil, instead of 0.33H, where H is the wall height.

• Journal of the Korean GEO-environmental Society
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• v.17 no.11
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• pp.45-53
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• 2016

A precast panel wall system resists against the horizontal earth pressure by increasing the shear strength of ground by reinforcement connected to the panel. The application of precast panel wall system is growing to lately minimize the earth work and environmental damage caused by large cut slope and to use the limited land effectively. The ground adhered panel wall system is the construction method that has the panel engraved with natural rock shape to improve the landscape. This system is developed to complete Top-Down method, and it is possible to have vertical cut, and to adhere to in-situ ground, improve construction ability by minimizing the ground relaxation and exclusion the trench and backfill process. In this study the field tests were performed to verify the construction ability about the vertical cut and complete Top-Down process and the construction behavior of ground adhered panel wall system was analyzed by large scale loading test and measurement results during loading test.

• Proceedings of the Korean Geotechical Society Conference
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• 2007.09a
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• pp.514-527
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• 2007

Earth reinforcement techniques are used worldwide and offer proven solutions to a wide range of geotechnical engineering problems. Here in this paper, recent developments of three major reinforced soil retaining wall methods in Japan were introduced in order to show how the current situation of this technique in Japan is. And the statistical data for the volume of the use was also shown, such as the total volume of the use, the scales of the structures, layout of the earth reinforcement, fill materials, and foundation conditions. Some of the case histories were also introduced with photographs and figures. And then, as one of recent research activity by the author, the study on the application of X-ray CT for the problem of earth reinforcement method combined with other method such as piling and soil improvement was introduced. In this study, a series of model test for several reinforced ground with geogrids was conducted using a newly developed test apparatus. Then, the behavior in the soil box was scanned after settlement using X-ray CT scanner. Based on these test results, the reinforcing effect by the geogrids and the soil arching effect over the pile heads was discussed precisely and those are done in 3-D with nondestructive condition. Finally, the effectiveness of the use of X-ray CT scanner in geotechnical engineering was promised.

• 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.