• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.2
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• pp.179-194
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• 2017

The segment lining design for shield tunnel is generally carried out by using the beam-spring model and the induced member forces from the model are strongly influenced by the components of the model such as imposed load, coefficient of subgrade reaction, location of segment joint and its stiffness. The structural models and stiffness of its connection part found used in abroad design cases is usually obtained as it is for the domestic design of segment of shield tunnel. Those models and stiffness in existing design cases are conventionally applied to a new tunnel design without any suitability review for the project. In this study, the application method of base components of the model such as the coefficient of subgrade reaction and modelling method to the segment lining design was suggested by carrying out the comparative study of the base elements for the member forces estimation of segment lining of shield tunnel.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.528-535
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• 2005

Using the case of design to the Large diameter Bored Pile, We showed the various method to estimate the Lateral coefficient of subgrade reaction and analyzed the lateral displacement behavior according to the characteristics of sub layer distribution. According to the study, Mutual relation to the N value and the soil modulus of deformation showed 400N to 800N to the fine grained soil and weathered soil. It showed simular tendancy with the proposed expression of Schmertmann. But Weathered rock was over estimated as 4,200N. $k_h$ to the sedimentory soil and weathered rock each showed these orded of Schmertmann-PMT-2,800N and Schmertmann-2,800N-PMT. As the factor($\alpha$) 4 was applied to the estimation in weathered rock, $k_h$ to the PMT was calculate as a big value. If the pile is long and the pile is surpported to the soil, Lateral displacement was in inverse proportion ratio to the value of $k_h$. But the case of shallow soil layer(early bedrock) and the short pile, Lateral displacement was affected by the behavior of socheted pile to the bedrock not by the upper soil layer.

• Structural Engineering and Mechanics
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• v.3 no.5
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• pp.429-443
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• 1995

The deformational response of plastic board drains installed to accelerate consolidation of soft soils, is examined as a problem of downdrag. The drain is modelled as a beam-column in which the axial load increases nonlinearly with depth. The soil response is represented by the Winkler medium whose coefficient of subgrade modulus increases linearly with depth. The governing equations for the drain-soil system are derived and solved as an eigenvalue problem. The critical buckling loads and the shape of the drain are obtained as functions of the normalized subgrade modulus of the soil at the top, the parameters signifying the variation of axial load along the length of the drain and the increase of subgrade modulus with depth. The derived deformed shapes of the drain are consistent with the observed ones.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.237-244
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• 2000

Piles are often subjected to both axial and lateral loads. The nonlinear subgrade reaction method is widely used for the design of laterally loaded piles and in this approach the soil reaction is replaced with a series of independent nonlinear Winkler springs. In this study, Laterally loaded high strength H-piles were analyzed using a finite difference solution, and three p-y curve models with different k values(the coefficient of horizontal subgrade reaction, ［FL$\^$-3/］) were evaluated using data obtained from various field tests, and another analysis method using Q$\sub$g/ - y$\sub$g/ curve was developed. The results of this analysis were compared with the measured values to assess their applicability.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.976-984
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• 2009

This study proposes a simple method that uses a simple mass-spring model to predict the natural frequency of a soil-pile-structure system in sandy soil. This model includes a pair of matrixes, i.e., a mass matrix and a stiffness matrix. The mass matrix is comprised of the masses of the pile and superstructure, and the stiffness matrix is comprised of the stiffness of the pile and the spring coefficients between the pile and soil. The key issue in the evaluation of the natural frequency of a soil-pile system is the determination of the spring coefficient between the pile and soil. To determine the reasonable spring coefficient, subgrade reaction modulus, nonlinear p-y curves and elastic modulus of the soil were utilized. The location of the spring was also varied with consideration of the infinite depth of the pile. The natural frequencies calculated by using the mass-spring model were compared with those obtained from 1-g shaking table model pile tests. The comparison showed that the calculated natural frequencies match well with the results of the 1-g shaking table tests within the range of computational error when the three springs, whose coefficients were calculated using Reese's(1974) subgrade reaction modulus and Yang's (2009) dynamic p-y backbone curves, were located above the infinite depth of the pile.

• Journal of the Society of Disaster Information
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• v.19 no.1
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• pp.31-43
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• 2023

Purpose: In this study, an analysis of the differences between the elastoplastic analysis and the numerical analysis and a study of the design ground constant recalculation method to derive similar trends in the analysis results were conducted. Method: The relational expression between the ground reaction force coefficient and the ground deformation coefficient at the time when the wall displacement becomes the same according to shallow excavation and deep excavation was derived. Result: Based on the measurement results, reverse analysis was performed to re-calculate the ground properties suitable for the site ground, and as a result of comparing and verifying the wall displacement using the derived formula and the literature formula, the proposed formula showed the most similar value. Conclusion: If the proposed formula is used, it will be helpful in practice because it is possible to infer the most similar ground properties to the actual at the time of design.

• Journal of the Korean Geotechnical Society
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• v.27 no.12
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• pp.97-106
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• 2011

To analyze the lateral load-deflection behavior of steel-concrete composite drilled shafts, a series of lateral pile load tests were performed. The test results were compared with the results from various analytical methods for lateral pile behaviors using the coefficients of subgrade reaction ($k_h$) estimated by pressuremeter test (PMT) and standard penetration test (SPT). As a result, it was found that the analytical methods using the $k_h$ estimated by SPT N value were not suitable for evaluating the pile head lateral load-deflections of the piles within the allowable deflection. However, the methods using the $k_h$ calculated from PMT were able to represent the initial lateral behavior at the head of the piles fairly well. Also, the method by the pressuremeter curve, which was applied directly to the p-y curve of the piles, offered a reasonable lateral behavior estimation by applying the correction factor to the pile materials.

• Journal of the Korean Geotechnical Society
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• v.26 no.1
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• pp.45-54
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• 2010

It is important to calculate the natural frequency of a piled structure in the design stage in order to prevent resonance-induced damage to the pile foundation and analyze the dynamic behavior of the piled structure during an earthquake. In this paper, a simple but relatively accurate method employing a mass-spring model is presented for the evaluation of the natural frequency of a pile-soil system. Greatly influencing the calculation of the natural frequency of a piled structure, the spring stiffness between a pile and soil was evaluated by using the coefficient of subgrade reaction, the p-y curve, and the subsoil elastic modulus. The resulting natural frequencies were compared with those of 1-g shaking table tests. The comparison showed that the natural frequency of the pile-soil system could be most accurately calculated by constructing a stiffness matrix with the spring stiffness of the Reese (1974) method, which utilizes the coefficient of the subgrade reaction modulus, and Yang's (2009) dynamic p-y backbone curve method. The calculated natural frequencies were within 5% error compared with those of the shaking table tests for the pile system in dry dense sand deposits and 5% to 40% error for the pile system in saturated sand deposits depending on the occurrence of excess pore water pressure in the soil.

• Journal of Ocean Engineering and Technology
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• v.23 no.6
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• pp.44-52
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• 2009

In this study, the behavior of a breasting dolphin with various dolphin heights and formations in the coastal area of Incheon was investigated. The dynamic deflection, shear stress, and moment of the pile were analyzed using the coefficient of the horizontal subgrade reaction that resulted from loading tests of different DWT (Dead Weight Tonnage). In the case of a vertical pile type dolphin, the deflection, shear stress, and moment increased as the dolphin height increased. In the case of the battered pile type dolphin, small values of shear stress and moment were shown at a low dolphin height, and the characteristics of the dynamic behavior of the dolphin showed that the deflection, shear stress, and moment increased as the pile slope of the dolphin decreased or the DWT increased.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.721-728
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• 2008

Top-Base Method is a stabilization method for light weight structures particularly in the soft ground. It is widely used for the increment of bearing capacity and the effect of restraining settlement when the bearing capacity of the ground is not enough. Top-shaped cone concrete foundations are installed in graveled laid over soft ground. The principle of the basic method is to maximize effect of dispersing the overburden pressure by increasing the contact area of the top-shaped cone. Therefore, the bearing capacity is increased and the settlement is decreased by the embedded resistance of pile part in the ground. In this paper, the plate bearing test was conducted to evaluate the feasibility of Top-Base foundation. Based on the test results, the coefficient of subgrade reaction, elastic modulus, and settlement of foundation on reclaimed land was derived.