http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
수정 Bouwer and Rice 법을 이용한 필터케이크가 존재하는 연직차수벽의 현장 투수계수 산정법
웽테바오,이철호,곽태훈,최항석 한국지반공학회 2009 한국지반공학회논문집 Vol.25 No.12
순간변위시험(Slug test)을 통해 대수층의 투수계수를 구할 때, 시험결과 해석에 적용하는 line-fitting법 중 가장 일반적인 방법이 Bouwer and Rice법이다. Bouwer and Rice법을 적용하여 압축성이 크고 벽체의 두께가 얇은 연직차수벽의 투수계수를 산정할 때는 세심한 주의가 필요하다. 그리고 연직 차수벽과 주변 지반 사이에 형성된 상대적으로 투수성이 낮은 영역, 즉 필터케이크(Filter cake)는 Bouwer and Rice법을 연직차수벽의 투수계수 산정시, 이 방법을 직접 적용하기 어렵게 만든다. 본 논문에서는 기존의 Bouwer and Rice법의 한계를 극복하기 위해서 유선망 개념을 도입한 수정 Bouwer and Rice법을 제안하였다. 수정된 Bouwer and Rice법은 연직차수벽의 투수계수를 산정할 때 필터케이크를 포함한 연직차수벽의 기하학적 조건을 효율적으로 반영할 수 있도록 한다. 또한, 수정 Bouwer and Rice법의 적용성을 검증하기 위한 사례 연구가 본 논문에서 수행되었다.
필터케이크(filter cake)를 고려한 슬러리월 연직차수벽의 현장투수계수 평가
웽테바오,이철호,최항석,김상균,Nguyen, The Bao,Lee, Chul-Ho,Choi, Hang-Seok,Kim, Sang-Gyun 한국지반공학회 2008 한국지반공학회논문집 Vol.24 No.11
In constructing a slurry trench cutoff wall, bentonite-water slurry is used to secure the stability of sidewalls during excavation before the wall is completed by backfilling. Unexpectedly, a thin but relatively impermeable layer called filter cake can be formed on the excavation surface, which significantly influences the result of slug test analysis in the cutoff wall if not considered. This study is to examine the effect of filter cake on evaluating hydraulic conductivity of the vertical cutoff wall through slug test analysis with the aid of the verified numerical program Slug_3D. The no-flux boundary conditions were adopted in Slug_3D to simulate the filter cake on the interface between the wall and the natural soil. A new set of type curves were built for applying the type curve method. New modification factors were obtained for using the modified line-fitting method. With consideration of filter cake, the type curve method and the modified line-fitting method were adopted to reanalyze the case study taken from EMCON (1995). The previous results achieved by Choi and Daniel (2006) without consideration of filter cake were compared with the present results obtained in this paper. The comparison emphasizes the necessity of considering filter cake when analyzing slug test results in vertical cutoff walls.
수정 fluid loss 시험을 이용한 연직 차수벽에 생성된 벤토나이트 필터케익 특성 평가
웽테바오,최항석,박문서,임지희,한신인 한국지반공학회 2011 한국지반공학회논문집 Vol.27 No.2
During the construction of vertical cutoff walls, filtration of bentonite slurry into the adjacent soil formation fabricates a layer of bentonite filter cake on the wall surface. The bentonite filter cake possesses much lower hydraulic conductivity compared to that of backfill materials in the cutoff wall. Hydraulic conductivity of bentonite filter cakes formed with three different types of bentonites has been measured by performing the modified fluid loss test under various pressure levels. Three different mixture ratios, 4, 6, and 8%, were selected for fabricating bentonite filter cakes to represent common field conditions. Two analysis methods for interpreting the experimental data from the modified fluid loss tests were employed to estimate hydraulic conductivity of the bentonite cakes. The range of hydraulic conductivities of the three bentonite cakes is between 2.15×10-11 m/s and 2.88×10-10 m/s which is 1 to 2.7 orders of magnitude lower than that of the design cutoff wall backfill. The stress distribution and thickness of the bentonite cakes were also evaluated in this paper.
Fluid loss 시험을 통한 벤토나이트 필터케익의 투수계수 평가
웽테바오 ( Nguyen The-bao ),이철호 ( Lee Chulho ),박문서 ( Park Moonseo ),길후정 ( Gil Hujeong ),최항석 ( Choi Hangseok ) 한국구조물진단유지관리공학회 2009 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.13 No.2
The mixture of bentonite powder and water is widely used in the construction of vertical cutoff walls to maintain the stability of excavation surfaces. The filter cake possesses a very low hydraulic conductivity compared to that of the cutoff wall. This paper presents the hydraulic conductivities of bentonite filter cakes of three types of bentonites measured by the modified fluid loss test under various pressure levels. Theory of filtration process was reviewed to explain the procedure in the experiment.
Fluid loss 시험을 통한 벤토나이트 필터케익의 투수계수 평가
웽테바오(Nguyen, The-Bao),이철호(Lee, Chulho),박문서(Park, Moonseo),길후정(Gil, Hujeong),최항석(Choi, Hangseok) 한국구조물진단유지관리학회 2009 한국구조물진단학회 학술발표회논문집 Vol.2009 No.2
The mixture of bentonite powder and water is widely used in the construction of vertical cutoff walls to maintain the stability of excavation surfaces. The filter cake possesses a very low hydraulic conductivity compared to that of the cutoff wall. This paper presents the hydraulic conductivities of bentonite filter cakes of three types of bentonites measured by the modified fluid loss test under various pressure levels. Theory of filtration process was reviewed to explain the procedure in the experiment.
벤토나이트 케익을 고려한 연직차수벽의 순간변위시험(slug test) 해석
임지희,웽테바오,이동섭,안재윤,최항석 한국지반공학회 2013 한국지반공학회논문집 Vol.29 No.6
Slug tests can be adopted to estimate hydraulic conductivity of the slurry trench wall backfill for its abilities to reflect the in-situ performance of the construction. A comprehensive three-dimensional numerical model is developed to simulate the slug test in a slurry trench wall considering the presence of bentonite cake on the interface boundaries between the wall and the surrounding soil formation. Influential factors such as wall width (i.e., proximity of wall boundary), well deviation, vertical position of well intake section, compressibility of wall backfill, etc. are taken into account in the model. A series of simulation results are examined to evaluate the bentonite cake effect in analyzing practical slug test results in the slurry trench wall. The results show that the modified line-fitting method can be used without any correction factor for the slug test in the slurry trench wall with the presence of bentonite cake. A case study is reanalyzed with the assumption of existing bentonite cake. The results are compared with the previously reported results by the approaches assuming no bentonite cake (constant-head boundary) or upper-bound solution (no-flux boundary). The case study demonstrates the bentonite cake effect and the validity of the modified line-fitting method in the estimation of the hydraulic conductivity of the slurry wall backfill.
연직차수벽의 비정상 지하수 흐름에 대한 이론해 : 순간변위시험(slug test) 적용과 투수계수 산정
임지희,이동섭,웽테바오,최항석 한국지반공학회 2012 한국지반공학회논문집 Vol.28 No.11
No analytical solution exists for evaluating in-situ hydraulic conductivity of vertical cutoff walls by analyzing slug test results with consideration of transient flow. There is an analytical solution proposed to interpret a slug test performed in a partially penetrated well within an aquifer. However, this analytical solution cannot be directly applied to the cutoff wall because the solution has been developed exclusively for an infinite aquifer instead of a narrow cutoff wall. To consider the cutoff wall boundary conditions (i.e, constant head boundary and no flux boundary condition), the analytical solution has been modified in this study to take into account the narrow boundaries by introducing the imaginary well theory. Type curves are constructed from the currently derived analytical solution and compared with those of a partially penetrated well within an aquifer. The constant head boundary condition provides faster hydraulic head recovery curve than the aquifer case. On the other hand, no flux boundary condition leads to slower hydraulic head recovery. The bigger the shape factor and deviation of the well and the smaller the width of the vertical cutoff wall are, the more effect of boundary condition was observed. The type curves obtained from the analytical solution for a cutoff wall are similar to those made by the numerical method in the literature.