• Title/Summary/Keyword: Terzaghi

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A study on the review of the Terzaghi's tunnel load theory (Terzaghi 터널토압의 재조명에 관한 연구)

  • Park, Si-Hyun
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.5 no.3
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    • pp.261-268
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    • 2003
  • Terzaghi's tunnel theory has been accepted to calculate tunnel loads conservatively in practical design until now. In this study, Terzaghi's tunnel theory was expanded to the inclined-layer ground with inclination of ground and stratification. Finally a new tunnel load equation was induced utilizing the original Terzaghi's tunnel theory and Terzaghi's tunnel theory was reviewed as well.

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Modification of Terzaghi's Earth Pressure Formula on Tunnel Considering Dilatancy of Soil (지반의 팽창성을 고려한 터널의 테르자기 토압공식 수정)

  • Han, Heui-Soo;Cho, Jae-Ho;Yang, Nam-Yong;Shin, Baek-Chul
    • Journal of the Korean GEO-environmental Society
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    • v.12 no.11
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    • pp.23-30
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    • 2011
  • In this study, Terzaghi's formula was modified to solve problems considering the dilatancy effect of the soil for estimating the earth pressure acting on tunnel. It is performed for the comparison with Terzaghi's formula and modified Terzaghi's formula, tunnel model test result of Kobe University Rock Mechanics Laboratory. From comparison results of the earth pressure acting on tunnel, the earth pressure calculated by the Terzaghi's formula was estimated largest value. The earth pressure measured through the tunnel model test was least value. The difference between the earth pressure derived from Terzaghi's original formula and that derived from the modified formula was caused by the dilation effect, which was caused by the soil volume change. The difference between the earth pressure derived from the modified formula and the earth pressure measured through the tunnel model test, earth pressure results from the energy making failure surface. The results of FEM analysis were almost consistent with the results of mathematical analysis.

The Study on Determination of the Coefficient of Terzaghi's Consolidation by Curve Fitting (Curve Fittig에 의한 Terzaghi의 압밀계수 산정방법 연구)

  • Kim, Chan Sik;Eam, Sung Hoon
    • Journal of The Korean Society of Agricultural Engineers
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    • v.56 no.1
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    • pp.101-107
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    • 2014
  • It has been known that Terzaghi's consolidation theory is not well consistent with the consolidation phenomenon on the soft clay ground, but this theory has still been adopted normally in practice because there is no method for estimating the consolidation settlement and rate easier than Terzaghi's theory. It is impossible to map whole part of consolidation settlement vs time curve to the curve of Terzaghi'z average degree of consolidation. If the primary consolidation and the secondary compression are happened same time, it would be useless of trying to find the end of primary consolidation, but it is needed for using Terzaghi's theory that the end of consolidation is determined to the time of beginning consistency between the final settlement analyzed with curve fitting and the experimented consolidation settlement.

Analysis of Tunnel Lining Behavior under Tunnel Load (이완하중을 받는 터널라이닝의 거동분석)

  • Park, Jung-Jin;Kim, Do-Hyun;Jeong, Sang-Seom
    • Journal of the Korean Geotechnical Society
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    • v.28 no.8
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    • pp.79-88
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    • 2012
  • In this study, the tunnel loads acting on the concrete lining are analyzed by comparing three methods - Terzaghi table, Terzaghi formula and Ground-Lining Interaction (G.L.I) model. The tunnel loads are analyzed by FLAC 2D. And the G.L.I model is analyzed under various rock mass ratings, tunnel depths (20~80m) and in-situ stress ratios ($K_0$=0.5~2.0). Terzaghi's method can be applied only to weathered rocks and soils, and cannot reflect the effect of various tunnel depths and in-situ stress ratio. The proposed G.L.I model can not only be applied to various ground conditions, but also relieves the tunnel loads by up to 30%.

Tunnel Pressure acting on Shallow Tunnel in Unconsolidated Ground (미고결 저토피 터널에 작용하는 토압에 관한 연구)

  • Lee, Jae-Ho;Akutagawa, Shinish;Kim, Young-Su;Moon, Hong-Duk
    • Tunnel and Underground Space
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    • v.17 no.6
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    • pp.453-463
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    • 2007
  • Terzaghi's tunnel pressure theory is generally used to estimate primary design pressures on tunnel support for shield and urban NATM tunnels until now. A trial is made in this paper to investigate the interaction between the ground deformation behavior and Terzaghi's tunnel pressure, which assumes pound's limit (or critical) state, by considering results of 'Terzaghi's tunnel pressure theory. two-dimensional reduced-scale model tunnel tests and nonlinear numerical analysis based on strain softening modeling. A full understanding between tunnel pressure and ground deformation behavior under the tunnel excavation and an effective utilization of this interaction lead to an economical tunnel support design and a safe construction of tunnel.

Earth Pressure Analysis of Tunnel Ceiling according to Tunnel Plastic Zone (터널 소성영역에 따른 터널 천단토압 해석)

  • Park, Shin-Young;Han, Heui-Soo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.11
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    • pp.753-764
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    • 2020
  • In this study, the plastic zone and internal earth pressure of the tunnel were calculated using the following three methods: metal plasticity to analyze the deformation of metal during plastic processing, Terzaghi's earth pressure theory from the geotechnical perspective and modified Terzaghi's earth pressure theory, and slip line theory using Mohr-Coulomb yield conditions. All three methods are two-dimensional mathematical analysis models for analyzing the plane strain conditions of isotropic materials. Using the theory of metallurgical plastics, the plastic zone and the internal earth pressure of the ground were obtained by assuming that the internal pressure acts on the tunnel, so different results were derived that did not match the actual tunnel site, where only gravity was applied. An analysis of the plasticity zone and earth pressure via the slip-line method showed that a failure line is formed in a log-spiral, which was found to be similar to the real failure line by comparing the results of previous studies. The earth pressure was calculated using a theoretical method. Terzaghi's earth pressure was calculated to be larger than the earth pressure considering the dilatancy effect.

An Experimental Study on the Settlement Characteristics of Soft Ground in the Central West Coast Region (서해안 중부지역 연약지반의 침하특성 분석을 위한 실험적 연구)

  • Kim, Joon-Seok
    • Journal of the Society of Disaster Information
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    • v.17 no.4
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    • pp.786-793
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    • 2021
  • Purpose: An experiment was conducted to analyze the characteristics of the settlement of soft clay soil in the central region of the west coast of Korea, which has a high silt content and is difficult to predict settlement due to various stress histories. Method: Field experiments were conducted for three cases. The settlement amount of the subsidence plate was measured in each case, and the following conclusions were drawn by analyzing Terzaghi's one-dimensional consolidation settlement amount, both the hyperbolic method and the Asaoka method. Result: The predicted value by Terzaghi was analyzed to be the largest in all cases, and it was predicted to be 111% to 187% larger than the subsidence plate settlement value. That is, the subsidence plate settlement value, which is the amount of settlement of the actual ground, showed a settlement of 53.4~89.9% compared to the predicted value of Terzaghi. Therefore, it was analyzed that the expected settlement of the Terzaghi method in the clay soft ground of the central west coast of Korea is more than the actual settlement. Conclusion: It was analyzed that the Asaoka method and the hyperbolic method presented relatively similar results, and in practice, predicting the settlement amount smaller than the actual settlement amount may cause a risk, so the hyperbola analysis method predicted 6~14% larger than the actual settlement amount can be used as a safety side.

A Study on the Self-Weight Consolidation Procedure of Very Soft Ground Reclaimed by Dredging Clayey Soil (연약한 준설 매립 점성토지반의 자중압밀 과정에 관한 연구)

  • 김형주;오근엽
    • Journal of the Korean Geotechnical Society
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    • v.15 no.2
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    • pp.129-138
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    • 1999
  • This study is performed for the development of a field monitoring and test technique both of self-weight and hydraulic consolidation by which the soil parameters of dredge-reclaimed clay can be obtained effectively. The field monitoring development and tests mentioned above make it possible to reproduce the process of the self-weight consolidation from settling to reclaimed soft ground. The experimental research is mainly focussed on the characteristics of self-weight consolidation of dredged clayey soil. And theoretical study has pointed out the limits in the application of Terzaghi's one dimensional consolidation theory in interpreting reclaimed clayey ground. Furthermore, a finite difference analysis has been made on the basis of Mikasa s self-weight consolidation theory which takes the problems of Terzaghi's theory into consideration. The relationships between specific volume, effective stress, and the coefficient of permeability of Kunsan reclaimed clayey soil have been obtained by laboratory tests. On the other hand, through the field monitoring, pore pressure, total pressure, and water levels have been measured after pouring. The results of these experiments have been analyzed, and compared with those from Terzaghi's method and the finite difference analysis of Mikasa's self-weight consolidation theory. In conclusion, the measured settlements is comparatively consistent with Mikasa's self-weight consolidation theory rather than Terzaghi's consolidation theory.

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Analysis of Isochrone Effect of Clayey Soils using Numerical Analysis (수치해석을 이용한 점성토 지반의 아이소크론 영향 분석)

  • Lee, Yun-Sic;Lee, Jong-Ho;Lee, Kang-Il
    • Journal of the Society of Disaster Information
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    • v.15 no.1
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    • pp.84-97
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    • 2019
  • Purpose: The consolidation settlement of soft ground is dependent on the distribution of pore water pressure which is also affected by hydraulic conductivities (boundary condition) of layers, thickness of clayey soil layer and surcharge. Results: However, the current consolidation analyses are mostly based on Terzaghi's consolidation theory that assumes the initial pore water pressure ratio with depth to be constant. In this study, numerical analysis are carried out to investigate the variation of pore water pressure dissipation with depth and thickness of clayey soil layer, time, surcharge as well as drainage conditions. Conclusion: Comparative study with Terzaghi's consolidation theory is also conducted. The result shows that Terzaghi's consolidation theory should be used with caution unless it is ideally corresponded to the isochrone.

Finite Difference Method on Consolidation under Time Dependent Loading (점증하중에 의한 압밀의 유한차분해석)

  • Lee, Seung-Hyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.4
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    • pp.1895-1899
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    • 2012
  • Formulation of finite difference method for analyzing consolidation were carried out. It can be seen that the differences in settlement with time obtained by FDM and Terzaghi method are diminished by fine discretization of time increment. Excess pore pressures predicted by the derived finite difference equation were same as those calculated by Olson's method. Predicted time-settlement behavior from the derived finite difference method were almost same as those calculated by Terzaghi's method and Olson's method. Analysis results obtained from the assumed multi-step time dependent loading are thought to be reasonable.