• Journal of the Korean GEO-environmental Society
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• v.22 no.8
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• pp.13-19
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• 2021

In the case of construction on soft ground - such as national expressways sponsored by Social Overhead Capital (SOC) - many problems occur due to excessive settlement: therefore, an accurate settlement prediction has a major impact on the selection of improvement methods, project budget and construction period. Most of the settlement prediction methods currently used in projects apply Terzaghi's Theory of One-Dimensional Consolidation which assumes the uniformity of the depth of the soft ground. However, the results of soft ground settlement predictions vary when the target layer is divided into multiple horizontal layers. This study analyzed the change in the consolidation settlement behavior according to the horizontal division of soft ground as well as with different loading height.

• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.6
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• pp.443-450
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• 2010

A concrete lining of NATM tunnel had been considered as interior materials. But recently we consider it as structural materials. Therefore we must consider various loads. Relaxed rock load is a main load which decides thickness and reinforcement presence of concrete lining. In practice conservatively, Terzaghi's rock load theory has been accepted to estimate relaxed rock loads in urban subway tunnel design. This study investigates the equations of relaxed rock loads used in the design of NATM concrete lining. Structural analysis are executed based on various equations of relaxed rock loads, and concrete lining forces are compared.

• Journal of The Korean Society of Agricultural Engineers
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• v.66 no.2
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• pp.1-12
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• 2024

In order to integrate two consolidation theories of Terzaghi's consolidation theory and Mesri's secondary compression theory and to identify a model suitable for analyzing stress-strain behavior over time, numerical analysis on consolidation tests were conducted using a modified cam-clay model and a soft soil creep model and the following conclusions were obtained. The results of numerical analysis applying the theory that a linear proportional relationship is established between the void ratio at logarithmic scale and the permeability coefficient at logarithmic scale is better agreement with the result of oedometer test than the results of applying constant hydraulic conductivity. The modified cam-clay model is a model that does not include secondary compression, but the slope of the normal consolidation line corresponding to the compression index of the standard consolidation test includes secondary compression, so the actual settlement curve over time is lower than the predicted value through numerical analysis. It always gets smaller. Other previous studies that applied Terzaghi's consolidation theory to consolidation test analysis showed the same results and were cross-confirmed. The soft soil creep model, which includes secondary compression in the theory, showed good agreement in all sections including secondary compression in the consolidation test results. It was judged appropriate to use a soft soil creep model when performing numerical analysis of soft clay ground.

• Journal of the Korean GEO-environmental Society
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• v.6 no.3
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• pp.25-34
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• 2005

The governing design point of shallow foundation is not its bearing capacity but its settlemen and N-value by the SPT is one of the key parameters for settlement estimation. However, if the N-value is more than 50/30, such as 50/10 or 50/20, the N-vlaues are not blow count of 30cm depth penetration. In these cases, the estimated settlements have big difference with the measured values because the applied maximum N value for the settlement estimation is 50. Therefore, in this study, the modified method for N-value estimation is suggested. The settlements by four methods, which are based on Elastic Theory with application of modified N-value, are compared with the Origina Plate Load Test data. The same comparision was carried out with another seven Empirical Methods. The result of this study showed that the error range of settlement is decreased from 260.4~2136.5% to 20.3~272.7%. Among four methods which are based on Elastic Theory, the original method by Elastic Theory is the most accurate with the application of modified N-value. Among Empirical Methods, Terzaghi-Peck's(1948, 1967) modified method 1 is the most accurate with the application of modified N-value. The differences between the original method by Elastic Theory and Terzaghi-Peck's(1948, 1967) modified method 1 are neglectable.

• Journal of the Korean Geotechnical Society
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• v.34 no.12
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• pp.19-27
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• 2018

Terzaghi proposed a 2D formula for arching based on the assumption of a vertical sliding surface induced in the upper part due to the downward movement of a trapdoor. The formula was later expanded to consider 3D tunnel excavation conditions under inclined sliding surfaces. This study further extends the expanded formula to consider the effects of different ground properties and inclined sliding conditions in the transverse and longitudinal directions considering anisotropic ground conditions, as well as 3D tunnel excavation conditions. The 3D formula proposed in this study was examined of the induced vertical stress under various conditions (ground property, inclined sliding surface, excavation condition, surcharge pressure, earth pressure coefficient) and compared with the 2D Terzaghi formula. The examination indicated that the induced vertical stress increased as the excavation width and length increased, the inclination angle increased, the cohesion and friction angle decreased, the earth pressure coefficient decreased, and the surcharge pressure increased. Under the conditions examined, the stress was more affected at low excavation lengths and by the ground properties in the transverse direction. In addition, The comparison with the 2D Terzaghi formula showed that the induced vertical stress was lower and the difference was highly affected by the ground properties, inclined sliding conditions, and 3D tunnel excavation conditions. The proposed 3D arching formula could help to provide better understanding of complex arching phenomena in tunnel construction.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.656-663
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• 2010

본 연구에서는 K.Terzaghi의 유효응력이론을 인용하여 압밀기반의 안전하중 산출 과정과 결과를 제시하였다. 일반적인 강도를 평가하기 위하여 이용된 J.I.Solovyov의 순간강도 이론에 기초를 두어, 제시한 방법은 포화된 연약점토지반에서 도로의 유지보수 뿐 아니라 축조 과정에 안전하중의 계산 적용이 가능하다. 실제로 편리한 표준 압밀 drain test에서 정의된 점착력, 내부 마찰각과 같은 강도정수를 가진 유효응력은 실제적 적용을 고려하기 위하여 산출된다.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.179-188
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• 2002

The scale effect should be considered to determine the bearing capacity and settlement of footings from plate-load test, because of the size difference between a footing and a loading plate. To analyze characteristics of bearing capacity and settlement according to the difference of loading plate sizes, model tests were performed with four different sizes of square plate, which are B=10, 15, 20, and 25cm respectively, on five different kinds of subsoils. Test results showed that the ultimate bearing capacity of a footing on the sand did not increase proportional to the traditional formula and the bearing capacity on the clay also increased a little with increasing the size of loading plate. The settlement of test plate on the sand did not increase as the traditional formula of Terzaghi and Peck (1967), and the settlement on the clay also did not increase proportional to the traditional formula.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.13 no.4
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• pp.282-289
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• 2001

This study analyzed the relationship between the physical properties of soil and the compression index of the soft clay in Gyungnam coastal region. Tests of physical and mechanical properties of soil have been carried out under the undisturbed condition at 82 Gimhae, 18 Jinhae and 27 Geojespecimens. The result showed that Terzaghi & Peck's empirical equation of the compression index were not applicable. The compression index of soft clay in Gyungnam coastal region was correlated with the water contents, the liquid limit and the initial void ratio. Among these, the initial void ratio showed the highest correlation with the compression index of soft clay in Gyungnam coastal region and the relationship is shown in the following. (1) The compression index of soft clay in Gyungnam coastal region is represented as follows: $C_c=0.74(e_o-0.7$ (2) The relationship between compression index and the swelling index in Gyungnam coastal region is represented as follows: $C_s=(1/8-1/15)C_c$.

• The Journal of Engineering Geology
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• v.22 no.1
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• pp.39-48
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• 2012

The behaviors of a diaphragm wall and a contiguous pile wall such as CIP(Case-in-place pile) and SCW(Soil-cement wall), applied to the top-down construction method, were analyzed using the SUNEX program, which is widely used to design earth retaining walls. Four types of earth pressures, as described by Rankine (1857), Terzaghi and Peck (1967), Tchbotarioff (1973), and Hong and Yun (1995a), were applied to the analysis program to predict the lateral displacement of walls. The results show that the displacements of an earth retaining walls vary with the applied earth pressure. The predicted lateral displacement based on Hong & Yun's (1995a) earth pressure is similar to the measured displacement. Therefore, the actual lateral displacement of an earth retaining wall, as applied to top-down construction method, can be accurately predicted by using an analysis program considering Hong and Yun's (1995a) earth pressure.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.2
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• pp.123-136
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• 2004

Terzaghi's one-dimensional consolidation theory has some important assumption, which can't be applicable to predict the behavior of soft clay ground. Especially, predictions using infinitesimal strain and linear material function related with permeability can give rise to mistake in comparison with the result of real behavior in site. For this reason, Gibson et al. established a rigorous formulation for the one-dimensional nonlinear finite strain consolidation theory, which can consider non-linearity of material function. But it is difficult to apply this theory to predict the behavior of common soft clay ground with vertical drain. In this study, consolidation model which can consider the vertical and horizontal flow of a fully saturated clay layer, self-weight of soil and nonlinear characteristics of compressibility and permeability are derived. Numerical analysis scheme, which can be applied to consolidation analysis by derived consolidation model in this study was developed. The characteristics of material function were examined using laboratory testing such as standard consolidation test, Rowe-cell test and modified consolidation test.