• Korean Journal of Soil Science and Fertilizer
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• v.42 no.2
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• pp.132-138
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• 2009

Soils originated from limestone, located at the southern part of Kangwon province and Jecheon, Danyang of Chungbuk province are mainly composed of fine texture, have different properties from soils originated from granite and granite gneiss, especially for water movement. This study was conducted for making PTF(Pedo-Transfer Function) for Kfs(field saturaton hydraulic conductivity) estimation, and for investigating the relation between soil particle distribution and the infiltration and percolation rate in soils originated from limestone. Soils used for the experiment were 6 soils of Gwarim, Mosan, Jangseong, Maji, Anmi and Pyongan series. Infiltration and percolation rate for the soil were measured by a disc tension infiltrometer and a Guelph permeameter, respectively. The particle size distribution and organic matter content of the soils were analyzed. Kfs was not related with sand, silt, clay, and organic mattrer (OM) content because of forest soils which contained high gravel, pebble, and cobble content, and O layer with high OM content. After Mosan soil series and O layer of Gwarim series were excluded for the data analysis, Kfs was explained as a linear function with sand and clay content and a exponential function with OM content. As a result, the PTF equation was obtained as Kfs=-4.20558+0.479706*(S)+0.023187*exp(1.829*OM) ($R^2=0.6558^{*}$).

• Proceedings of the Korea Contents Association Conference
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• 2011.05a
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• pp.465-466
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• 2011

이 연구는 일본식 배수공이 설치된 제방의 침투 흐름을 비정상 상태로 SEEP/W 모형을 사용하여 해석하고 모형의 적용성을 평가하기 위해 수행하였다. 수치모형의 적용성 평가를 위해 비정상 상태로 제방 침투에 대한 수리모형실험을 수행하였다. 제체 재료는 경상북도 구미시에 위치한 해평천의 제방 건설 현장의 재료를 사용하였고 일본식배수공은 굵은 골재와 부직포를 사용하여 실험실에 제방 축소 모형을 수조 내부에 제작하였다. 모형제방은 제방축조 방법과 유사하게 다짐을 하기 위해 흙을 쌓으면서 0.20 m 높이마다 다짐을 실시하였다. 다짐방법은 고무망치를 이용한 층다짐을 하였다. 제방 제외지에 0.55 cm/min의 속도로 수위를 증가하여 15분 간격으로 각 0.3 m, 0.4 m, 0.5 m 수위에 따른 비정상 상태의 위압계 측정을 수행하였다. SEEP/W 모형의 매개변수는 투수계수와 입도분포도, 불포화 함수특성곡선(값을 산정하기 어려움)이 있으며, 각 매개변수에 대한 민감도 분석을 수행하였다. SEEP/W 모형의 모의 결과는 수리모형실험 결과와 비교적 잘 일치함을 알 수 있었다.

• Journal of the Korean GEO-environmental Society
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• v.11 no.12
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• pp.37-45
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• 2010

The particle size of microfine cement(MC) is so small that it can be injected into silt layer. But the more particle size is miniaturized, the more the cohesion increases. This phenomenon results in the decrease of the perviousness of MC. In this study, the grouting effects of microfine cement with superplasticizer to maintain cohesion low and that of normal cement were investigated in rock. To estimate the grouting effects, TCR/RQD test for rock quality, lugeon test, borehole loading test for coefficients of elastic and deformative stress, borehole shear test for shear stress, detection p~q~t(pressure~flow~time) chart tests were carried out. The results using MC show a better permeability, modulus of elasticity, deformation, charge per unit, and recover efficiency of grouting material than those of ordinary portland cement except shear stress.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.17-22
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• 2009

계절에 따른 토양공극의 수리학적 변화를 파악하기 위해서 설마천 유역의 범륜사 독립사면과 광릉 원두부 소유역의 독립사면을 대상으로 장력침투실험을 실시하였다. 토양수분 확보에 신뢰를 받기위해서 TDR(Time Domain Reflectometry)및 현장에서 토양의 불포화 투수계수 측정이 가능한 장력침투계(Tension infiltrometer)를 이용하였다. 계절에 따른 자료수집을 위해서 2008년 3월 20일 부터 약 6주간격으로 10월 29일까지 5회에서 6회 토양수분 자료 및 토양장력침투 자료를 획득하였다. 획득한 자료를 이용하여 포화 및 불포화 수리전도도, 대공극 유효흐름분율(macropore flow), 대공극 유효부피분율을(effective macroporosity) 나타내었다. 분기별로 자료분석 결과 계절별 특성이 나타남을 알 수 있다. 수리전도도는 3월, 5월, 10월은 유사한 반면 6월과 7월 그리고 9월은 상대적으로 높았다. 이는 여름철에 공극 발달이 활발하다는 것을 의미한다. 선행토양수분은 수리전도도에 영향을 미치는 것으로 나타났다. 대공극의 발달은 삼림과 같은 복잡 경관에서는 강우사상에 따른 토양수분의 공간 분포 및 이송, 유출과정이 물순환에 영향을 미친다. 지형분석을 통한 공극의 흐름특성과 토양수분 유의성에 대하여 논의하였고, 대공극 변화에 밀접한 관계가 있는 식생과 그밖에 계절적으로 발달을 일으키는 요인을 모색 하였다. 본 연구는 계절에 따라 변하는 수리전도도를 기초로 하여 불포화대에서 토양공극의 수리학적 변화와 시공간적으로 침투흐름에 얼마나 영향을 주는가를 보여준다.

• The Journal of Engineering Geology
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• v.3 no.2
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• pp.149-165
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• 1993

Nowadays, the field hydraulic test is still an only method to evaluate groundwater characteristics in subsurface. The results of hydraulic test are very important for the concept model of fracture hydrogeology as well as the geometric pattern of fractures. The hydraulic tests performed in Korea are generally analysed under such assumption as steady radial flow in homogeneous aquifer or along simple geometry of fractures. Also the transmissivity measured in a fixed interval length is equivalent to a sum of individual fracture transmissivities in test legth. The boundary effects of weH hydraulics and the geometry of flow paths are hardly obtained from the test results analysed by a steady flow method. To circumvent this problem, the flow dimensional analysis was attempted from the results of constant pressure injection test carried out in a fractured granite area. A comparison of the hydraulic conductivity values from the transient and steady analysis shows that the latter is about a factor of 2~3 higher than the former. However, it was possible to analyse a flow dimension of each test interval from flow rate variation with time. The upper part of the bedrock(<10m deep) indicates an open boundary and the flow dimension shows nearly steady states, while the lower part of the bedrock(>25m deep) is characterized as sublinear flow dimension with a dosed boundary. In one of the test sections(15m deep), the flow dimension was changed from linear flow to spherical flow. From the experience of this study, one of the immediate problems to be solved is to enhance the field testing equipments, i.e., an accurate flowmeter with autorecording and a pressure detecting device to be able to install in the test section.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.551-557
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• 2007

This paper describes a study on the permeability reduction of the riverbed ground during urban railway tunnel construction. The research is mainly concentrated on the study of the grouting or injection methods among permeability reduction methods which can be adapted in the riverbed ground. Firstly, the various grouting methods are theoretically reviewed and compared based on the previous research papers and case study results. It is also evaluated the grouting methods in view of a safe construction of the river crossing railway tunnel. Baced on the literature review and previous construction data, the design technology of grouting methods considering the long term hydro-geological behaviour in the riverbed, is suggested. Two injection methods namely, Natural Durable Stabilizer(N.D.S) and Space-Multi Injaction Grouting(S.M.I) methods, are introduced as new approach methods which can be adopted to modify the riverbed ground. In order to evaluate the ground that grouted and modified by the N.D.S and S.M.I method, the pilot test programmes including the field and laboratory permeability tests, are carried out in the river crossing tunnel construction sites. The results obtained from pilot test programme, are also reviewed. In conclusion, the grouting efficiency of the S.M.I method using the non-alcalimeter silica sol is better than that of NDS method using cement. In addition, it hopes that the research results are contributed to develop the grouting design technology.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.3
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• pp.41-47
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• 2009

Post-tensioned concrete pavement(PTCP) was developed to built long-span concrete pavement(120 m span) and to maintain long-term service life(over 40 years) of concrete pavement. In the present study, research for high-durable concrete was conducted to utilize the advantage of PTCP construction method efficiently. First of all, 20% of fly ash(by binder weight) was replaced to control alkali silica reaction. Second, silica fume was applied to improve the water-permeability and early-age strength. Results of tests for mechanical properties, water-permeability resistance, and surface-scaling resistance of ternary blended cement concrete showed that the early-age strength was improved significantly with addition of silica fume. The water-permeability resistance was improved from "Low" to "Very Low"(ASTM C 1202). However, surface-scaling resistance was decreased with an increase of silica fume, therefore, content of silica fume should be kept in less than 5%(by binder weight) to assure field application considering durability. The results of air-void analysis showed that durability factors were improved since spacing factors were estimated as 250$\pm$15 micron in adjusted mixtures.

• Journal of the Korean Geotechnical Society
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• v.21 no.3
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• pp.133-140
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• 2005

In order to accelerate the rate of consolidation settlement and gain a required shear strength for a given soft clay deposit, vertical drain method combined with a preloading technique has been widely applied. In this paper, a theory of axisymmetric nonlinear consolidation fer drainage-installed deposit, which considers secondary compression (or creep) during primary consolidation, as well as the variations of compressibility and permeability during the consolidation process, has been developed. A computer program named AXICON based on Hypothesis B fur the analysis of axisymmetric nonlinear consolidation was developed by adopting finite difference method. The results of AS(ICON were compared with Hansbo's solution based on Hypothesis A, as well as in-situ settlements and pore pressures measured in test embankment of Ska-Edeby. The results indicated that Hypothesis A usually underestimated the in-situ settlement and Hypothesis B was considered to be logically correct. It was also shown that one may able to appropriately predict the real in-situ behaviors using the proposed program.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.5
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• pp.485-500
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• 2020

Due to various advantages such as small facilities, ease of construction and so on, the grouting technology which is widely used in construction field has developed remarkably compared with the past. However, the efforts to improve the homogeneity of quality, long-term durability and environmental problems have been continued. In recent years, new grouting method has been developed in order to solve problems such as low strength, durability and leaching phenomenon of liquid glass (sodium silicate) grouting material in Korea. A newly developed method integrates the injection material with the ground by the self-healing material of crystallization growth type. For this reason, it is known that improvement of the durability and water quality of the ground, prevention of leaching, and environment friendliness can be expected. The present study applied a newly developed method to test sites and verified its effect such as injection range, improvement effect, waterproofing performance and so on. Standard penetration test, field permeability test, borehole shear test, pressuremeter test and pH test were conducted, and the results were compared between before and after developed method application. As results of tests, the field applicability and improvement effect of developed method were proved to be excellent.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.159-163
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• 2006

하천 건천화라 함은 수문학적 요소기준으로 갈수량 기준 이하이고, 하천으로부터 필요 수량을 지속적으로 제공할 수 없는 하천이라 정의하고 있다($\ulcorner$프론티어 연구개발사업 '지속가능한 하천수 개발 기술'$\lrcorner$). 건천화의 원인으로는 우리나라 기상특성상 호우기에 집중되는 호우로 인한 저류효율 저하와 더불어 무분별한 도시개발로 인한 불투수층의 증가로 지하수위가 저하되는 것을 꼽을 수 있다. 여기에 무분별한 하천수 취수 및 하수처리를 위한 차집 등이 하천수를 감소시키는 요인으로 작용한다. 하천 건천화는 정체수역의 악취발생 및 주변경관 저해 등으로 지역주민에게 피해를 주는것은 물론 생태계의 파괴를 초래하게 된다. 이러한 하천 건천화의 가장 주요한 원인은 도시화에 따른 하천유역의 물순환 체계가 파괴됨에 있다. 이러한 문제점을 분석하고 해결방안을 모색하기 위하여 수자원의 지속적 확보기술개발 사업단에서 추진중인 '안양천 유역의 물순환 건전화 기술 개발' 과업에서는 지자체에서 운영하고 있는 안양천 유역내의 기존 관측 시설과 사업단 1단계 사업성과로 설치된 실시간 수문모니터링 시설을 이용하여 수문자료를 지속적으로 모니터링하고 있다. 따라서 본 연구에서는 안양천 수계내의 건천화 구간에 대하여 지난 2년간의 하천수위, 지하수위 관측자료와 유량측정자료를 이용하여 발생 유량에 대한 수문특성 변화를 분석하였으며, 주요 지점에 대한 현장조사를 통하여 건천화 발생 요인에 대한 접근을 시도하였다.