• Title, Summary, Keyword: Pore water pressure

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Estimation of the Degree of Consolidation using Settlement and Excess Pore Water Pressure (침하량과 과잉간극수압을 이용한 압밀도의 추정)

  • 이달원;임성훈
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.44 no.3
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    • pp.111-121
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    • 2002
  • This study was performed to estimate the degree of consolidation using excess pore water pressure in the very soft ground. The final settlement prediction methods by Hyperbolic, Asaoka and Curve fitting methods from the measured settlement data were used to compare with the degree of consolidation estimated by excess pore water pressure. The dissipated excess pore water pressure during embankment construction and the peak excess pore water pressure on the completed embankment were used for the estimation of the degree of consolidation. After completion of embankment, it was concluded that the degree of consolidation estimated from dissipated excess pore water pressure was more reliable than that from the peak excess pore water pressure. And, the degree of consolidation estimated from the surface settlement was nearly the same as settlement of each layer. The degree of consolidation estimated from dissipated excess pore water pressure was a little larger than that from settlement.

Evaluation of pore water pressure on the lining during tunnel operation (운영 중 터널에 작용하는 간극수압 평가기법)

  • Shin, Jong-Ho;Shin, Yong-Suk;Choi, Kyu-Cheol
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.10 no.4
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    • pp.361-369
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    • 2008
  • Control of ground water is one of the most important factors for long-term operation of tunnel because most of tunnel is located in the ground. In case of leakage tunnel, there is no pore water pressure on the lining when the drainage system is properly working. After long-term operation, however, the pore water pressure can be developed on the lining due to the deterioration of the drainage system. The increased pore water pressure on the lining is termed here as 'residual pore water pressure'. Residual pore water pressure can be measured by piezometer, but it is generally not allowed because of damages of drainage system. Therefore, an indirect and nondestructive method is required for evaluating the residual pore water pressure. Moreover, understanding of pore water pressure is needed during healthy operation of the lining. In this study, a new method for evaluation of pore water pressure on the lining during operation is proposed using theoretical and numerical analysis. It is shown that the method is particularly useful for stability investigation of pore water pressure on the lining during operation using theoretical analysis with normalized pore water pressure curve.

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Consolidation Behavior of Agricultural Reservoir under Embankment on Soft Clay (연약지반상에 축조된 농업용 저수지의 압밀거동)

  • Oh, Bum-Hwan;Lee, Dal-Won
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • pp.313-316
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    • 2002
  • This study was performed to evaluation the consolidation behavior of agricultural reservoir in the very soft ground. The final settlement prediction methods by Hyperbolic and Asaoka methods were used to compare with the degree of consolidation estimated by exess pore water pressure. The dissipated excess pore water pressure during embankment construction and peak excess pore water pressure on the completed embankment were suggested for the estimation of the degree of consolidation. It was concluded that the degree of consolidation estimated from dissipated excess pore water pressure was more reliable than that from the peak excess pore water pressure.

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Behavior of failure of agricultural reservoir embankment due to overtopping (월류에 의한 저수지 제체의 붕괴 거동)

  • Lee, Dal-Won;Noh, Jae-Jin
    • Korean Journal of Agricultural Science
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    • v.39 no.3
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    • pp.427-439
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    • 2012
  • In this study, an experiment with large-scale model was performed according to raising embankment in order to investigate the behaviour of failure due to overtopping. The pore water pressure, earth pressure and settlement by high water level, a rapid drawdown and overtopping were compared and analyzed. Also, seepage analysis and slope stability analysis were performed for steady state and transient conditions. The pore water pressure and earth pressure for inclined core type showed high value at the base of the core, but they showed no infiltration by leakage. The pore water pressure and earth pressure by overtopping increased at the upstream slope and core, it is considered a useful data that can accurately estimate the possibility of failure of the reservoir. The behavior of failure due to overtopping was gradually enlarged towards the downstream slope from reservoir crest, and the inclined core after the raising embankment was influenced significantly to prevent the reservoir failure. The pore water pressure distribution for steady state and transient condition showed positive (+) pore water pressure on the upstream slope, it was gradually changed negative (-) pore water pressure on the downstream slope. The pore water pressure by overtopping showed a larger than the high water level at the downstream slope, it was likely to be the piping phenomenon because the hydraulic gradients showed largely at the inclined core and reservoir crest. The safety factor showed high at the steady state, and transient conditions did not show differences depending on the rapid drawdown.

Response analysis of tunnel lining considering pore pressure (수압을 고려한 터널 라이닝의 응답 해석)

  • Kim, Ki-Tae;Kim, Young-Jae;Park, Du-Hee
    • 한국방재학회:학술대회논문집
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    • pp.541-544
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    • 2008
  • Generally numerical analysis of tunnel lining, under dynamic loading condition, performed not considering pore pressure. But if tunnel excavated under the surface of water, such as bottom of the sea, the river bed, tunnel lining can take pore water pressure. It may be different from evaluated numerical analysis not considering pore pressure. Therefore tunnel design should consider effect of water pressure acting on tunnel lining.

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Evaluation of the Degree of Consolidation using Settlement and Excessive Pore Water Pressure (침하량과 간극수압에 의한 압밀도의 평가(지반공학))

  • 이달원;임성훈;윤제식;김지문
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • pp.444-450
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    • 2000
  • This study was performed to analyze the degree of consolidation by the dissipation of excessive pore water pressure and final settlement prediction methods of the very soft clay. Hyperbolic method, Asaoka method and curve fitting method were used to compute the degree of consolidation. The degree of consolidation with excessive pore water pressure were used to compute, which considered the dissipation time with embankment construction. The degree of consolidation that was obtained by the peak excessive pore water pressure was less than in the case of the dissipation excessive pore water pressure. And, the degree of consolidation by the total settlement was nearly the same value that of layer settlement. The degree of consolidation that was obtained by excessive pore water pressure was larger than in the case of the settlement.

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Estimation of Degree of Consolidation in Soft Ground Using Field Measurements and Rheology Model (현장 계측치와 유변학적 모형을 이용한 연약지반의 압밀도 추정)

  • Lee, Dal-Won;Yoon, Hyun-Jung
    • Journal of The Korean Society of Agricultural Engineers
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    • v.47 no.2
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    • pp.87-96
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    • 2005
  • In this research, an attempt is made to derive the practical estimation of the degree of consolidation in soft clay from field measurements under embankments. For the practical estimation of pore water pressure in soft clay, the elasto-viscous rheological model was proposed, with a transform of parameters and a field geotechnical measurements in southern Korea. By using the rheological properties of soft clays and the dissipation of excess pore water pressure behaviour during step loading, a degree of consolidation or pore water pressure estimation in the future can be performed, and are shown to be generally close to the field measurements of pore water pressure. Finally, a pore water pressure behaviour in soft clay can be explained through measured data in field and the excess pore water pressure data can also be used to estimate settlement.

An Empirical Study on the Characteristics of Pore Water Pressure Reaction in Colluvium Model (붕적층내의 간극수압 반응에 관한 실험적 연구)

  • 정두영;최길렬
    • Geotechnical Engineering
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    • v.8 no.2
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    • pp.59-70
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    • 1992
  • This work is to study experimentally the measurment of pore air pressure according to rainfall in colluvium model and the characteristics of pore water pressure according to increasement of artesian ground water head. After modeling a geological feature of the Tertiary formation, the experiment was performed about sixty times on three kinds of soil. This experimental results showed the variation of pore water and pore air pressures with time, the change of void ratio and appling pressure head in the nonsaturated soil. It can be also expressed by the final pore water and the air reaction ratios and then formularizing the relationship between the permeability coefficient and the void ratio. In the results of this experiment, the patterns of the pore water pressure reaction are classified by the step-type and the wave-type, and the time-lag to reach final point of pore water pressure is in order sand, sandy silt and clayey sand.

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Behavior of Pore Water Pressure of Agricultural Reservoir According to Raising Embankment (농업용 저수지 둑 높이기에 따른 제체의 공극수압 거동)

  • Lee, Dal-Won;Lee, Young-Hak
    • Journal of The Korean Society of Agricultural Engineers
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    • v.54 no.3
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    • pp.11-17
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    • 2012
  • In this study, an experiment with large-scale model was performed according to raising embankment in order to investigate the cause of collapse by a change in water level of reservoir. Also, the settlement and pore water pressure by high water level and a rapid drawdown were compared and analyzed. After raising embankment for inclined core, there was no infiltration by leakage. For the vertical core, the pore water pressure showed a largely change by faster infiltration of pore water than in the inclined core. In a rapid drawdown, inclined core was remained stable but vertical core showed a largely change in pore water pressure. A settlement after a raising embankment showed a larger measure of settlement than before the raising embankment. The leakage quantity before a raising embankment and an inclined extension showed no leakage. Leakage in vertical extension was measured 160 $l$. From the result, a instrument system that can accurately estimate a change of pore water pressure shall be established for a rational maintenance and stabilization of raising embankment for agricultural reservoir.

The Behavior of Undrained Pore Water Pressure in Normally Consolidated and Saturated Clay(II) - Visco Elastic Analysis Model - (포화된 정규압밀 점성토에서 비배수 공극수압의 거동(II) - 점탄성 해석 모델 -)

  • 임성훈
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.45 no.4
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    • pp.137-143
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    • 2003
  • The initial condition of $\Delta \sigma_3 \;=\; \Delta u$ is used for analyzing the time dependent behavior of ground. This is based on the concept that the coefficient of pore water B is the unity on the condition of saturation. but some measured consolidation data in the field showed that the pore water pressure was not dissipated as time elapsed but it was maintained constant value or it's dissipation rate was slower than that of the predicted. and so the measured data of pore water pressure was not consistent with that of settlement. In this study, the rheological model for the pore water pressure behavior on undrained condition was induced and compared with the experiment data of the literature. The result showed that the suggested model was consistent well with the result of experiment, but the suggested model could not explain the effect of the decrease of void ratio according to consolidation.