• Journal of the Korean Geotechnical Society
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• v.40 no.2
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• pp.65-79
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• 2024

This study employs traditional statistical auto-regressive integrated moving average (ARIMA) and deep learning-based long short-term memory (LSTM) models to predict the deformation of earth retaining walls using inclinometer data from excavation sites. It compares the predictive capabilities of both models. The ARIMA model excels in analyzing linear patterns as time progresses, while the LSTM model is adept at handling complex nonlinear patterns and long-term dependencies in the data. This research includes preprocessing of inclinometer measurement data, performance evaluation across various data lengths and input conditions, and demonstrates that the LSTM model provides statistically significant improvements in prediction accuracy over the ARIMA model. The findings suggest that LSTM models can effectively assess the stability of retaining walls at excavation sites. Additionally, this study is expected to contribute to the development of safety monitoring systems at excavation sites and the advancement of time series prediction models.

• Geotechnical Engineering
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• v.23 no.8
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• pp.20-26
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• 2007

• Journal of the Korean Geosynthetics Society
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• v.8 no.1
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• pp.41-51
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• 2009

This paper reviews many of the design considerations surrounding the topic of tiedback landslide suppressor walls primarily for soils app1ications. The design requires combining knowledge of many aspects of soil mechanics and geology to obtain a design a wall that fits site specific conditions. Many of the aspects necessary to complete the design are stil1 not comprehensively studied or understood. This paper provides an overview of the more traditional aspects of tieback wall design and a discussion of newer issues such as suppressor wall earth pressures and rotation of stresses due to tiebacks. An overview is also provided regarding the effect of seismic forces.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.1
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• pp.89-96
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• 2008

The study, with regard to unsymmetrically inclined backfilled wall, was intended to estimate the lateral earth pressure, develop the equation for lateral earth pressure and eventually identify the mutual behavior, based on the modified Kellogg theory, while changing the width between the walls, wall angle, relative density and wall friction angle. To verify the geostatic pressure obtained from the study, the results in the wake of 62 kinds of model tests performed were compared and evaluated with the behaviors based on theoretical equations. As a result, the wall inclination angle was found to be the factors affecting the earth pressure the most, when both walls were inclined unsymmetrically. And the narrower the backfill space and the larger the wall inclination angle to the horizontal level, the greater the effect of the wall friction. The equation considering the wall friction reaction indicated the value, which was closer to the actually-measured earth pressure, and when the width between the warts was narrow, the arching effect appeared to be great, thereby indicating the difference between the measured earth pressure, theoretically calculated earth pressure and the geostatic pressure proved to be insignificant.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.4
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• pp.555-565
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• 2018

Nowadays, the artificial ground freezing (AGF) method has been used in many geotechnical engineering applications such as temporary excavation support, underpinning, and groundwater cutoff. The AGF method conducts the freezing process by employing a refrigerant circulating through a set of embedded freezing pipes to form frozen walls serving as an excavation support and cutoff wall. Two refrigerants of brine with the freezing temperature of $-20{\sim}-40^{\circ}C$ and liquid nitrogen with the freezing (evaporating) temperature of $-196^{\circ}C$ are commonly being used in geotechnical applications. This paper performed a series of field experiments to evaluate the freezing rate of marine clay in application of the AGF method. The field experiments consisted of the single freezing-pipe test and the frozen-wall formation test by circulating liquid nitrogen, which is a cryogenic refrigerant, into freezing pipes constructed at a depth of 3.2 m in the ground. The temperature of discharged liquid nitrogen was maintained through the automatic valve, and the temperature change induced by AGF method was measured at the freezing pipes and in the ground with time. According to the experimental results, the single freezing-pipe test consumed about 11.9 tons of liquid nitrogen for 3.5 days to form a cylindrical frozen body with the volume of about $2.12m^3$. In addition, the frozen-wall formation test used about 18 tons of liquid nitrogen for 4.1 days to form a frozen wall with the volume of about $7.04m^3$. The radial freezing rate decreased with increasing the radius of frozen body because the frozen area at a certain depth is proportional to the square of the radius. The radial freezing rate was formulated as a simple equation.

• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.15-26
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• 2003

Urban excavation requires highly reliable prediction technique for the design and construction of earth retaining structure in order to protect adjacent structures around deep excavation. Application of the pre-loading of bracing for deep excavation has been reported, and the known beneficial effects are not fully understood and recognized by many practitioners. Model tests have been carried out to evaluate the efficiency of pre-loading system in reducing ground settlement as well as prediction of structural damage around excavation in sand. The test results revealed that the applied pre-loading of 50% and 70% showed about 20% of reduction in horizontal wall displacement and 30∼40% reduction in ground settlement. Also, bracing forces and earth pressure distribution behind the wall have been monitored during pre-loading at various excavation stages.

• Journal of the Society of Disaster Information
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• v.9 no.4
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• pp.462-468
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• 2013

Walls for preventing floods using overturning or buoyancy method have been developed as replacement construction for preventing floods in and outside country. However, as they have some problems with pre-inspection and maintenance control, Eco-moving wall structure for preventing floods was studied and first developed using Glass Fiber Reinforced Composite which has not only light weight but outstanding strength. The developed wall structure for preventing floods offering structural stability and field applicability through numerical analysis was confirmed to reduce construction expenses by around 87~95% and secure waterproof property with the inside of the wall installed rubber water stopper.

• Journal of the Korean Geotechnical Society
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• v.34 no.10
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• pp.51-60
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• 2018

Recently, a cylindrical cut-off wall was proposed as a new technology for temporary offshore works. The cut-off wall has a cylindrical shape, so seepage analyses are necessary to analyze the effect of wall shape. In this study, a numerical analysis was performed to investigate the seepage discharge inside cut-off walls. The numerical modeling was verified by comparing with the theoretical solution for the cofferdam with double sheet piles. Two different flow conditions were compared between 2-dimensional flow and axisymmetric flow. The results showed that the discharge of the axisymmetric flow was about 1.55 times larger than that of 2-dimensional plain flow. A parametric study was carried out by varying wall radius, penetration depth of the wall, and total head difference between in and outside of the wall. The discharge decreased with the increase of the penetration depth and the wall radius. Finally, the design equations were suggested to determine the discharge for the preliminary design of the cylindrical cut-off wall.

• Journal of the Korean Geotechnical Society
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• v.25 no.1
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• pp.21-29
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• 2009

On plane strain condition, many researchers have investigated the earth pressure according to the shape of wall, and standardized method has been applied to the design of the retaining wall. But on cylindrical diaphragm wall, at-rest earth pressure has been generally used. Even though this method is on conservative side, it may lead to over-design. In this paper, the application of convergence confinement method to the calculation of the earth pressure acting on the cylindrical diaphragm wall of a shaft was suggested. In addition, a model test was carried out to investigate the distributions of earth pressure. Model test results show that the earth pressures of diaphragm wall are about 1.4 times larger than active earth pressure and about 0.8 times less than at-rest earth pressure.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.65-73
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• 2002

Underground flexible pipes for electric cables are subject to external loads and surrounding soil pressure. Particularly, strain of flexible pipes is of great concern in terms of safety and maintenance for electric cables. In this paper, stress and strain of flexible pipes with various depth are compared using traditional formula, FEM analysis and model soil box test. The results show that theoretical values are more conservative in strain in comparison with model soil box test and FEM analysis. Considering the strain criteria - maximum 3.5%, flexible pipes can be buried at the depth of 40cm without additional soil improvement. From the result of this study, deformation formula compatible with the field condition was proposed.