• Journal of the Korean GEO-environmental Society
• /
• v.4 no.3
• /
• pp.5-17
• /
• 2003

Using Rowe cell for vertical and lateral consolidate test, we concerned characteristics of vertical and lateral consolidation, and permeability on the remolded Decompoed Mudstone Soil in Phoang, and then, compared it with Oedometer test results. Indirect coefficients of permeability were calculated by the results of the coefficient of consolidation that were derived from 9 different kinds of methods. The values of indirect coefficients of permeability derived from ${\sqrt{t}}$ method and hyperbolic method were similar to the results of direct coefficients of permeability with respect to vertical drainage, but, in the case of lateral drainage, for all kinds of methods, the values of indirect coefficients of permeability showed overestimated ones. With vertical and lateral direct coefficient of permeability, by investigating the anisotropic effect with respect to permeability on Decomposed mudstone soil, we obtained average value, 13, with respect to anisotropic characteristics for all kinds of consolidation loadings.

• The Journal of Engineering Geology
• /
• v.18 no.1
• /
• pp.27-36
• /
• 2008

To derive easily the coefficient of permeability from several other soil properties, the estimation model of coefficient of permeability was proposed using linear regression analysis. The coefficient of permeability is one of the major factors to evaluate the soil characteristics. The study area is located in Kangwon-do Pyeongchang-gun Jinbu-Myeon. Soil samples of 45 spots were taken from the study area and various soil tests were carried out in laboratory. After selecting the soil factor influenced by the coefficient of permeability through the correlation analysis, the estimation model of coefficient of permeability was developed using the linear regression analysis between the selected soil factor and the coefficient of permeability from permeability test. Also, the estimation model of coefficient of permeability was compared with the results from permeability test and empirical equation, and the suitability of proposed model was proved. As the result of correlation analysis between various soil factors and the coefficient of permeability using SPSS(statistical package for the social sciences), the largest influence factor of coefficient of permeability were the effective grain size, porosity and dry unit weight. The coefficient of permeability calculated from the proposed model was similar to that resulted from permeability test. Therefore, the proposed model can be used in case of estimating the coefficient of permeability at the same soil condition like study area.

• Journal of the Korean Geotechnical Society
• /
• v.17 no.4
• /
• pp.249-257
• /
• 2001

본 논문에서는 경남 양산지역의 퇴적층에서 채취한 불교란 시료를 이용하여 표준압밀시험($IL_{CON}$)과 일정변형률(CRS, Constant Rates of Strain) 압밀시험을 수행한 후 각각의 시험결과를 분석하여 양산점토의 투수특성을 고찰하였다. 이를 위하여 투수계수와 간극비의 관계를 Kozeny(1927)와 Carman(1956) 이후 제안된 많은 연구결과와 비교, 검토하였으며, 시료를 연직방향으로 성형하여 CRS 시험을 수행한 후 횡방향투수계수를 산정하여 양산점토의 투수계수의 이방성을 살펴보았다. CRS시험 결과, 직접적으로 정상류를 발생시켜 누수계수를 측정하는 Rowe cell 시험에 비하여 상대적으로 투수계수의 이방성이 과소평가되는 경향을 보였다. 또한 현장 투수계수에 영향을 미치는 요소들을 살펴보고, 깊이에 따른 투수계수를 고찰하였다.다.

• Journal of Korea Water Resources Association
• /
• v.33 no.1
• /
• pp.133-142
• /
• 2000

Series of tests were carried out to study permeability characteristics of unsaturated soils. The weathered soils taken from Inju, Sungwhan, and Kuri, were selected to have different amount of fine grained soils in order to find a possible correlation between the unsaturated permeability behavior and fine grained soils contents. Measurements of permeability for unsaturated soils were performed with a newly developed apparatus, which modeled after Klute's apparatus(1965a). The apparatus was designed to measure volumetric water content and permeability by applying incremental suction pressure. Permeability and volumetric water content of unsaturated soils generally decreased as density of the soil increased. The relationship between volumetric water content and permeability was not related to the fine grained soils contents because the plots scattered widely. By comparing volumetric water content with permeability, empirical parameters A and B could be determined, which made to be possible to predict unsaturated permeability from soil-moisture characteristics.

• Journal of the Korean Geotechnical Society
• /
• v.20 no.3
• /
• pp.47-51
• /
• 2004

An unsaturated hydraulic conductivity function and a soil-water characteristic curve are the essential constitutive factors in studying unsaturated soils. In order to obtain the unsaturated hydraulic conductivity function, prediction functions, which are based on the soil-water characteristic curve, have been used because it is difficult to measure the unsaturated hydraulic conductivity function directly. In this study, a parameter estimation method using the flow pump technique is introduced to determine the unsaturated hydraulic conductivity function. This method provides more accurate and independent solution than previous methods for the determination of the unsaturated hydraulic conductivity function which is not subordinate to the soil-water characteristic curve or prediction models.

• Journal of the Korean Geotechnical Society
• /
• v.26 no.10
• /
• pp.49-60
• /
• 2010

Unsaturated permeability function is an important factor in the design and analysis of various unsaturated soil structures. Generally the permeability characteristics decrease as the mat ric suction increases and the trend is similar to water retention characteristics of a soil. The permeability of unsaturated soils can be obtained directly by laboratory tests or indirectly by estimation methods from other soil properties. For unsaturated soils sampled from 7 areas in KOREA, SWCCs and unsaturated permeability functions were obtained by experimental tests. The unsaturated permeability results were also compared with the unsaturated permeability functions derived from the SWCCs theoretically. However, the current estimation models of unsaturated permeability function did not express the unsaturated permeability characteristics. Therefore, the FXK-M permeability function was modified to predict more accurate permeability functions for Korean weathered soils using a correction factor that can be calculated from the air-entry value of SWCC. The new estimation model resulted in good agreements for all tested soils.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.3
• /
• pp.2229-2233
• /
• 2015

The permeability of HMA(hot mixed asphalt) is a major influencing factor for long-term performance of the pavement. Especially, the lift thickness of the pavement during construction causes a wide range of physical properties of HMA. This study investigates the correlationship between the lift thickness and the physical properties of HMA through a series of laboratory experiments. The specimens were cored from a construction site of the dense graded asphalt pavement. The cored samples have various lift thickness and the number of compaction for the study. The results of the study show that the permeability of the sample decreases with the apperant density and t/NMAS, and the air void ratio. Therefore, the commonly used construction method as a constant lift thickness regardless of conditions needs to be reconsidered.

• Journal of the Korean Geotechnical Society
• /
• v.25 no.12
• /
• pp.47-55
• /
• 2009

As a conventional line-fitting method, the Bouwer and Rice method has been popularly adopted to estimate the hydraulic conductivity of an aquifer through a slug test. Because a vertical cutoff wall is usually very compressible and features a small wall thickness, the Bouwer and Rice method should be carefully applied to analyzing slug test results to estimate the hydraulic conductivity of vertical cutoff walls. In addition, a relatively impermeable layer, called a filter cake, formed at the interface between the cutoff wall and the natural soil formation makes it difficult to use the Bouwer and Rice method directly. In order to overcome such limitations, the original Bouwer and Rice method has been modified by incorporating the concept of the flow net method. In this modification, the geometry condition of cutoff walls including the filter cake is effectively considered in evaluating the hydraulic conductivity of a vertical cutoff wall.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2011.05a
• /
• pp.387-391
• /
• 2011

국내에서 사면 붕괴의 직접적인 원인은 강우에 의한 것으로 볼 수 있으며, 강우침투에 따른 지하수위 상승과 간극수압 증가, 강우강도 크기에 직접적으로 영향을 받는 지표면 유출로 인한 사면의 표면토사 유출 및 얕은 사면붕괴로 나타난다. 본 연구에서는 강우로 인한 지반내 침투로 불포화토가 포화토로 변화는 과정에서 침투능을 산정하고자 기존의 침투공식을 검토하고 TDR 센서를 이용한 실내실험을 통한 침투능 산정공식을 제시하였다. 제시한 침투능 산정공식을 검증하기 위한 침투실험을 수행하여 결과를 비교 분석하였으며, 이론적 해석 및 실내실험에 의한 결과는 다음과 같다. 첫째, 포화도 변화에 따른 TDR데이터 변화는 일정했으며 이를 회귀분석을 통하여 함수화하였고, 이 함수를 이용하여 지반의 포화도 및 함수비를 파악할 수 있었다. 둘째, 흡인수두항과 중력수두항이 결합된 연속적인 침투능 산정공식을 새로이 유도하였으며, 이를 이용한 결과와 TDR 센서를 이용한 실험결과와 거의 유사함을 알 수 있었다.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.22 no.1
• /
• pp.25-33
• /
• 2010

The matching condition at a perforated wall with vertical slits involves the permeability parameter, which can be calculated by two different methods. One expresses the permeability parameter in terms of energy dissipation coefficient and jet length at the perforated wall, being advantageous in that all the related variables are known, but it gives wrong result in the limit of long waves. The other expresses the permeability parameter in terms of friction coefficient and inertia coefficient, giving correct result from short to long waves, but the friction coefficient should be determined on the basis of a best fit between measured and predicted values of such hydrodynamic coefficients as reflection and transmission coefficients. In the present study, an empirical formula for the friction coefficient is proposed in terms of known variables, i.e., the porosity and thickness of the perforated wall and the water depth. This enables direct estimation of the friction coefficient without invoking a best fit procedure. To obtain the empirical formula, hydraulic experiments are carried out, the results of which are used along with other researchers' results. The proposed formula is used to predict the reflection and transmission coefficients of a curtain-wall-pile breakwater, the upper part of which is a curtain wall and the lower part consisting of a perforated wall with vertical slits. The concurrence between the experimental data and calculated results is good, verifying the appropriateness of the proposed formula.