• Title/Summary/Keyword: pore pressure

Search Result 1,291, Processing Time 0.022 seconds

A Study on the Proper Pore pressure ratio in Continuous Loading Consolidation tests (연속재하 압밀시험에서 적정 간극수압비에 관한 연구)

  • Chae, Sum-Sik;Lee, Song
    • Proceedings of the KSR Conference
    • /
    • 2002.05a
    • /
    • pp.271-276
    • /
    • 2002
  • Continuous loading is applied the sample has been developed to overcome some of the problems associated with the incremental loading consolidation test. Therefore, it is able to reduce the test time and provide a well defined the curve of effective stress versus strain due to continuous stress-strain points. Also, the constant rate of strain consolidation(CRSC) test has been accepted widely as a standard method in foreign countries because of its many advantages. However, in Korea the CRSC test has not been used in engineering practice and experimentally verified. Because there is not a precise criterion of testing despite consolidation characteristics are influenced on strain rate and Pore pressure ratio. Consequently, it is difficult to apply in engineering practice. In this study, artificial neural networks are applied to the estimation of th proper strain rate and pore pressure ratio of the CRSC test. This study shows the possibility of utilizing the artificial neural networks model of estimation of the strain rate and pore pressure ratio in the CRSC test.

  • PDF

Modeling of Dissipation of Excess Pore Pressure in Liquefied Sand Grounds (액상화 지반의 과잉간극수압 소산 모델링)

  • Kim, Sung-Ryul;Hwang, Jae-Ik;Ko, Hon-Yim;Kim, Myoung-Mo
    • Proceedings of the Earthquake Engineering Society of Korea Conference
    • /
    • 2006.03a
    • /
    • pp.89-96
    • /
    • 2006
  • Recently, many researches on the dissipation of excess pore pressure in liquefied sand grounds have been performed to evaluate post-liquefaction behaviors of structures. In this paper. centrifuge tests were performed to simulate liquefaction behaviors of prototype soil. The evaluation model of solidified layer thickness was developed to simulate non-linear variation of solidified layer thickness with time. Also, the dissipation of excess pore pressure in liquefied sand was evaluated by applying the solidification theory and the consolidation theory. The developed model gives a good estimation of the solidified layer thickness and the time history of excess pore pressure.

  • PDF

Thermal stress and pore pressure development in microwave heated concrete

  • Akbarnezhad, A.;Ong, K.C.G.
    • Computers and Concrete
    • /
    • v.8 no.4
    • /
    • pp.425-443
    • /
    • 2011
  • Most previous studies have generally overlooked the contribution of thermal stresses generated within the concrete mass when subjected to microwave heating and reported on pore-pressure as being the dominant cause of surface spalling. Also, the variation in electromagnetic properties of concrete and its effects on the microwave heating process have not been studied in detail. In this paper, finite element modeling is used to examine the simultaneous development of compressive thermal stresses and pore-pressure arising from the microwave heating of concrete. A modified Lambert's Law formulation is proposed to estimate the microwave power dissipation in the concrete mass. Moreover, the effects of frequency and concrete water content on the concrete heating rate and pattern are investigated. Results show high compressive stresses being generated especially in concrete with a high water content when heated by microwaves of higher frequencies. The results also reveal that the water content of concrete plays a crucial role in the microwave heating process.

Lateral Stress and Pore Pressure During One-dimensional Consolidation of Clay (점토의 일차원 압밀과정중 작용하는 수평토압과 간극수압)

  • 김재영
    • Journal of the Korean Geotechnical Society
    • /
    • v.20 no.6
    • /
    • pp.5-10
    • /
    • 2004
  • The earth pressure coefficient at rest for clayey soils in the one-dimensional state, $K_0$ obtained from the triaxial test is not correct in principle because the seepage flow is radial and the displacement of soil elements is three-dimensional. Measurements of the earth pressure and the pore water pressure during one-dimension consolidation in the consolidometer ring are presented. The earth pressure and pore water pressure are measured directly by a circular part of the consolidometer ring of a floating type at its mid height. A plastic clay showed $K_0$=0.5 irrespective of pressure in the consolidometer ring.

Growth of silicon nitride whiskers using tailored pores (제어된 기공을 이용한 질화규소 휘스커의 성장)

  • Kim, Chang-Sam;Han, Kyong-Sop;Kim, Shin-Woo
    • Journal of the Korean Crystal Growth and Crystal Technology
    • /
    • v.15 no.2
    • /
    • pp.61-67
    • /
    • 2005
  • In this study a new growing method of silicon nitride whiskers in the inside of large pores made intentionally during the sintering was conducted. Pore size, pore vol%, and nitrogen pressure were used as experimental variables. Silicon nitride whiskers were well grown in the inside of pores with low pore vol% range from 14 to 27 but not grown with high pore vol% such as 39 and 50. On the other hand, pore size and nitrogen pressure did not have any influence on the whisker growth. Therefore the most important factor to grow silicon nitride whisker in the inside of large pores during sintering was to make pores isolated or closed.

The Effects of Stress and Time History on Pore Pressure Parameter of Overconsoldated clay (과압밀점토의 간극수압계수에 응력이력과 시간이력이 미치는 영향)

  • 김수삼;김병일;한상재;신현영
    • Journal of Korean Society of Coastal and Ocean Engineers
    • /
    • v.14 no.4
    • /
    • pp.286-294
    • /
    • 2002
  • This study investigated the effects of stress and time history of overconsolidated clayey soils on pore pressure parameter, A. Laboratory tests were carried out under the conditions of both varying stress and time history. The stress history is classified into (i) rotation angle of stress path, (ii) overconsolidation ratio, and (iii) magnitude of length of recent stress path. The time history is divided into (i) loading rate of recent stress path and (ii) rest time. Pore pressure parameters are different both in the magnitude and trend with the rotation angle, depending on the magnitude of overconsolidation ratio but not in a trend. In addition, the pore pressure parameters have no effects on the magnitude of length of recent stress path except the level of initially small strain, while loading rates of recent stress path have effects on it. Finally, the pore pressure parameters of overconsolidated clays increase with the existence of the rest time, until either the deviator stress exceeds 70 kPa or the strain up to 0.1%.

An integrated model for pore pressure accumulations in marine sediment under combined wave and current loading

  • Zhang, Y.;Jeng, D.-S.;Zha, H.-Y.;Zhang, J.-S.
    • Geomechanics and Engineering
    • /
    • v.10 no.4
    • /
    • pp.387-403
    • /
    • 2016
  • In this paper, an integrated model for the wave (current)-induced seabed response is presented. The present model consists of two parts: hydrodynamic model for wave-current interactions and poro-elastic seabed model for pore accumulations. In the wave-current model, based on the fifth-order wave theory, ocean waves were generated by adding a source function into the mass conservation equation. Then, currents were simulated through imposing a steady inlet velocity on one domain and pressure outlet on the other side. In addition, both of the Reynolds-Averaged Navier-Stokers (RANS) Equations and $k-{\varepsilon}$ turbulence model would be applied in the fluid field. Once the wave pressures on the seabed calculated through the wave-current interaction model, it would be applied to be boundary conditions on the seabed model. In the seabed model, the poro-elastic theory would be imposed to simulate the seabed soil response. After comparing with the experimental data, the effect of currents on the seabed response would be examined by emphasize on the residual mechanisms of the pore pressure inside the soil. The build-up of the pore water pressure and the resulted liquefaction phenomenon will be fully investigated. A parametric study will also be conducted to examine the effects of waves and currents as well as soil properties on the pore pressure accumulation.

Development of Stress Based on Pore Pressure Model (응력 기반 간극수압 모델 개발)

  • Park, Du-Hee;Ahn, Jae-Kwang;Kim, Jin-Man
    • Journal of the Korean Geotechnical Society
    • /
    • v.28 no.5
    • /
    • pp.95-107
    • /
    • 2012
  • Even though the importance of predicting build-up of pore pressure under cyclic loading is recognized, effective stress analysis is rarely performed due to difficulties in selecting the parameters for the pore pressure model. In this paper, a new stress based numerical model for predicting pore pressure under cyclic loading is developed. The main strength of the model is that it is easy-to-use, requiring only the CSR-N curve in selecting the parameters. Another advantage of the model is that it can be used for any loading pattern and therefore can be implemented in an effective stress time-domain dynamic analysis code. The accuracy of the model is validated through its comparisons with measurements in literature and laboratory test data collected in Korea. Further comparisons with another stress based pore pressure model highlighted the superiority of the proposed model.

Pore Water Pressure Characteristic of Unsaturated Weathered Granite Soil Slopes through Rainfall Simulation (강우재현모형실험에 의한 불포화 화강풍화토 사면의 간극수압 특성)

  • Kim, Sun-Hak
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.10 no.11
    • /
    • pp.3287-3295
    • /
    • 2009
  • This present study implemented a rainfall simulation system, and performed simulation and numerical analysis according to rainfall and slope conditions using a model slope built with weathered granite soil. Extensive analysis were conducted on the characteristics of changes in volumetric water content and pore water pressure measured in the simulation, and compared them with the results of numerical analysis. It took longer for the volumetric water content to reach the limit when rainfall intensity was high and the slope was steep and shorter when rainfall intensity was low and the slope was gentle. When rainfall intensity was low and the duration of rainfall was short, negative pore water pressure was higher and the time for restoration was shorter. On the contrary, when rainfall intensity was high and the duration of rainfall was long, it took a longer time to restore negative pore water pressure. In the results of rainfall simulation and numerical analysis, the distribution of volumetric water content and pore water pressure was similar between the two. However, the volumetric water content was different by up to 5%, and pore water pressure by up to 3kPa.

Effective Method for Remodeling of Deteriorated Agricultural Reservoirs (노후화된 농업용 저수지의 효율적인 리모델링 방법)

  • Lee, Young Hak;Lee, Dal Won
    • Journal of The Korean Society of Agricultural Engineers
    • /
    • v.59 no.4
    • /
    • pp.43-52
    • /
    • 2017
  • This study analyzed pore water pressure, earth pressure and settlement through laboratory model tests in order to suggest the effective remodeling method in the case of reinforcing the upstream and downstream slope of deteriorated reservoirs that has no cores and filters or is not functional. The method of remodeling the upstream slope using dredge soil is first prevent seepage by installing the core, and the leakage water can be rapidly discharged through a filter installed on the downstream slope. Therefore, it is considered a highly efficient method of remodeling that reduces piping phenomena and increasing the storage capacity of the reservoir. The variation of earth pressure without the core and filter was greater than with it, while the change largely showed in the upstream slope, the downstream slope did not show any significant changes. The remodeling method of the downstream slope with the core appeared differently pore water pressure depending on the presence of the vertical and horizontal filters. In the upstream slope, the pore water pressure rises sharply, the base and middle gradually increased, and the downstream slope appeared small. The pore water pressure of embankment with a vertical and horizontal filter will be smaller than without it. The remodeling of deteriorated reservoir that does not have the function of the filter, the vertical filter must be installed in a position that is higher than the expected seepage line by removing portions of the downstream slopes. Since the horizontal filter is an important structure that provides stable drainage during an earthquake or concentrated leak, it is necessary to examine any change in the seepage characteristics depending on the filter intervals via three-dimensional finite element analysis, and it should be connected to the tow-drain to reduce the possibility of the collapse of the reservoir.