• Geomechanics and Engineering
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• 제18권6호
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• pp.567-574
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• 2019

In order to study the effect of stress and water pressure on the permeability of fractured rock mass under three-dimensional stress conditions, a single fracture triaxial stress-seepage coupling model was established; By using the stress-seepage coupling true triaxial test system, large-scale rock specimens were taken as the research object to carry out the coupling test of stress and seepage, the fitting formula of permeability coefficient was obtained. The influence of three-dimensional stress and water pressure on the permeability coefficient of fractured rock mass was discussed. The results show that the three-dimensional stress and water pressure have a significant effect on the fracture permeability coefficient, showing a negative exponential relationship. Under certain water pressure conditions, the permeability coefficient decreases with the increase of the three-dimensional stress, and the normal principal stress plays a dominant role in the permeability. Under certain stress conditions, the permeability coefficient increases when the water pressure increases. Further analysis shows that when the gob floor rock mass is changed from high stress to unloading state, the seepage characteristics of the cracked channels will be evidently strengthened.

• Geomechanics and Engineering
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• 제37권2호
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• pp.179-187
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• 2024

In this paper, a unified time-dependent constitutive model of Darcy flow and non-Darcy flow is proposed. The influencing factors of flow velocity are discussed, which demonstrates that permeability coefficient is the most significant factor. Based on this, the dynamic evolution characteristics of water inrush during tunneling through fault fracture zone is analyzed under the constant permeability coefficient condition (CPCC). It indicates that the curves of flow velocity and hydrostatic pressure can be divided into typical three stages: approximate high-velocity zone inside the fault fracture zone, velocity-rising zone near the tunnel excavation face and attenuation-low velocity zone in the tunnel. Furthermore, given the variation of permeability coefficient of the fault fracture zone with depth and time, the dynamic evolution of water flow in the fault fracture zone under the variable permeability coefficient condition (VPCC) is also studied. The results show that the time-related factor (α) affects the dynamic evolution distribution of flow velocity with time, the depth-related factor (A) is the key factor to the dynamic evolution of hydrostatic pressure.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.1053-1056
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• 2008

콘크리트의 투수계수는 콘크리트 구조물의 내구성능 및 미세구조의 밀실성을 판단하는 핵심적인 재료 매개변수이다. 투수계수를 산정하기 위한 많은 연구들이 있었으나, 시멘트 페이스트 및 골재 각각이 콘크리트의 투수성능에 미치는 영향을 다룬 연구는 드물다. 더우기, 탄산화가 염소이온의 확산계수에 큰 영향을 미칠 수 있음에도 불구하고, 탄산화된 콘크리트에 대한 확산계수를 다룬 연구는 더욱 드문 실정이다. 본 연구의 목적은 탄산화 및 비탄산화된 콘크리트의 투수계수를 추정할 수 있는 기초적 접근방법을 개발하는 것이다. 본 연구에서는 미세구조 모델 및 시멘트의 경화특성을 기초로 투수계수를 산정할 수 있는 해석적 기법이 개발되었다. 본 연구에서는 시간단계별로 변화하는 투수계수의 해석과 중성화된 콘크리트의 투수계수이다. 탄산화된 콘크리트에서 감소된 공극량이 계산되었으며 이는 투수계수의 산정에 이용되었다. 본 연구결과는 실험적 결과를 얻어서 상호 비교하여 검증하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 연약지반처리위원회 학술세미나
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• pp.93-112
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• 2000

The permeability of converter slag, replacing material of sand mat on improving soft clay foundation, was evaluated in the laboratory. The effects of grain size, flow water time and aging were investigated using sea and fresh water. Converter slag being submerged with fresh water, the coefficients of permeability in A and B samples less than 10mm grain sizes were measured as 6.52${\times}$10$\^$-2/cm/sec and 5.99${\times}$10$\^$-1/cm/sec, while changed as 1.88${\times}$10$\^$-2/cm/sec, 3.86${\times}$10$\^$-1/cm/sec under sea water condition. Also, the condition of turbulent flow may exit and was experimentally identified from the relationship between hydraulic gradient and seepage velocity. After 180 days on using sea water, the coefficients of permeability of sample A and B samples decreased ten times smaller than those initial values. And after that time continually decreased as for till 360 days. The reduction of permeability coefficient was considered to influence filled with voids in high-calcium quicklime(CaO). However, in-situ coefficient of permeability was practically satisfactory.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 연약지반처리위원회 학술세미나
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• pp.12-31
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• 2000

The permeability of converter slag, replacing material of sand mat on improving soft clay foundation, was evaluated in the laboratory. The effects of grain size, flow water time and aging were investigated using sea and fresh water. Converter slag being submerged with fresh water, the coefficients of permeability in A and B samples less than 10mm grain sizes were measured as 6.52${\times}$10$\^$-2/cm/sec and 5,99${\times}$10$\^$-1/cm/sec, while changed as 1,88${\times}$10$\^$-2/cm/sec, 3.86${\times}$10$\^$-1/cm/sec under sea water condition. Also, the condition of turbulent flow may exit and was experimentally identified from the relationship between hydraulic gradient and seepage velocity. After 180 days on using sea water, the coefficients of permeability of sample A and B samples decreased ten times smaller than those initial values. And after that time continually decreased as for till 360 days. The reduction of permeability coefficient was considered to influence filled with voids in high-calcium quicklime(CaO). However, in-situ coefficient of permeability was practically satisfactory.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.985-990
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• 2001

Chloride permeability of high strength concrete(HSC) was investigated using saltwater pending test and rapid chloride permeability test by electrical potential(ASTM C 1202). The lower water-cement ratio concrete showed the lower diffusion coefficient of chloride. The relationship between the diffusion coefficient of chloride and charge passed by the rapid chloride permeability test could be obtained. This relationship appears to be an effective method for evaluating chloride permeability of low water-cement HSC.

• 한국의류산업학회지
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• 제22권1호
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• pp.112-118
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• 2020

This paper examined the water repellency, water proofing and water vapor permeability of twelve types of woven fabrics for sports wear clothing. Their physical properties were compared and discussed with the fabric structural parameters and surface finishing effect. A water repellent property of 100% was obtained in the coated or laminated water repellent finished fabrics; in addition, cotton/nylon breathable composite fabrics treated with a laminated finishing and with low fabric density showed a 90% water repellency. Water proofing fabric above 6,000 mm H₂O hydraulic pressure was achieved by coated or laminated finishing; however, high density fabric or medium-level coated fabrics exhibited 100% water repellent and low water proofing characteristics. Superior water vapor permeability characteristics with good water repellency and proofing properties were achieved at the 2.5 layered low density and with 0.7 - 0.9 cover factor nylon fabrics treated with hydrophilic laminated finishing. The regression analysis for examining the effects of fabric structural parameters and surface finishing such as coating and laminating to the water vapor permeability exhibited a high determination coefficient of fabric structural parameters of 63.5%; in addition,, main factors among fabric structural parameters appeared to be cover factor and fabric thickness per weight. Coating and Laminating factors exhibited determination coefficient of water vapor permeability parameters of 36.5%.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2005년도 학술발표논문집
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• pp.393-398
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• 2005

In order to treat flow problems for an unsaturated soils, it is required the mediation of the coefficient of permeability with variation of suction. The coefficient of permeability for soils can be determined by the direct or indirect methods. The direct methods of permeability can be performed either in the laboratory or in the field. The indirect methods can be predicted from the soil-water characteristics curve. Laboratory test methods to measure the coefficient of permeability can be categorized into two types, steady-state and unsteady-state. In this study, the coefficient of permeability for unsaturated soils was determined by the modified apparatus for steady state-method(Klute, 1972) and was predicted from the equations of Brooks and Corey(1964) and Van Genuchten(1980). Experimental results were compared with predicted coefficient of permeability and verified applicability of the two equations.

• 대한토목학회논문집
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• 제36권2호
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• pp.207-217
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• 2016

투기계수는 콘크리트의 공극뿐만 아니라 공극크기, 공극분포, 공극간의 굴곡특성에 의해서도 영향을 받는다. 투기계수는 시멘트 페이스트의 미세구조에 의해 지배되는데, 시멘트 페이스트 및 골재 각각이 콘크리트의 투기성능에 미치는 영향을 다룬 연구는 드물다. 더우기, 탄산화가 투기계수에 큰 영향을 미칠 수 있음에도 불구하고, 탄산화된 콘크리트에 대한 투기계수를 다룬 연구는 더욱 드문 실정이다. 본 연구의 목적은 탄산화 및 비탄산화된 콘크리트의 투기계수를 추정할 수 있는 기초적 접근방법을 개발하는 것이다. 본 연구에서는 미세구조 모델 및 시멘트의 경화특성을 기초로 투기계수를 산정할 수 있는 해석적 기법이 제안되었다. 탄산화된 콘크리트에서 감소된 공극량이 계산되었으며 이는 투기계수의 산정에 이용하여 탄산화된 콘크리트의 투기계수를 계산하였다. 높은 물-시멘트비를 갖는 콘크리트는 탄산화로 인하여 투기계수의 감소가 더욱 뚜렷한 것을 확인되었다. 한편, 시멘트 페이스트에서 투기계수와 투수계수는 Klinkenberg 효과에 의한 선형관계가 성립되나, 콘크리트에서는 성립되지 않았다. 해석결과는 YOON's 실험방법을 수행하여 검증하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.334-341
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• 2004

The coefficient of permeability is one of the most important properties in unsaturated soils. The permeability varies with change in the water content as the soil water characteristic curve(SWCC) does. Thus the permeability curve of unsaturated soils has the similar shape with the soil-water characteristic curve(SWCC). Therefore, the methodologies have been studied to simply predict the unsaturated permeability from the SWCC. In this study, the experimental tests of SWCC and permeability were carried out for domestic weathered granite soils. The SWCC test results were fitted to Fredlund and Xing's SWCC equation and then it was found that there are some relationships between the parameters of SWCC equation and the basic soil properties. Accordingly we used an ANN(artificial neural network) model to obtain the SWCC parameters from the basic soil properties. Finally, the coefficients of permeability were predicted from these results by a prediction model.