• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.655-666
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• 2013

A number of highway projects are in progress in Korea to accommodate increasing transportation demands. As the highway route becomes more complex, some projects include tunneling through unconsolidated sedimentary rock. Since an unconsolidated sedimentary rock mainly consists of rock and ground mass, the behavior and characteristics in unconsolidated sedimentary rock tunnel are quite different from typical rock tunnel. However, construction case histories and rock classifications method on unconsolidated sedimentary rock tunnel had not been developed or studied domestically. Consequently the case studies and rock classification system for unconsolidated sedimentary rock are required to better understand its behavior for tunneling. In this study, rock mass classification method is proposed to identify unconsolidated sedimentary rock based on point load and slake durability tests. Based on this, the proposed method of unconsolidated sedimentary rock can be applied well through comparisons with the results of convergence measurement.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.11b
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• pp.115-140
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• 2002

이암층, 함탄층, 석회암층과 같은 특수지질불량구간에서 터널과 암반사면의 합리적인 시공을 달성하기 위해서는 먼저 대상지질에 대한 지질특성, 암반특성을 정확히 이해하는 것이 필요하며, 지반특성에 적합한 지보대책을 수립하도록 하여야 한다. 본고에서는 전형적인 퇴적암지층으로 알려진 포항지역중 중생대 퇴적암류로부터 신생대 제 3기의 미고결 퇴적암류에 이르는 다양하고 복잡한 지질구조를 이루고 있는 지역에서의 터널 및 암반사면의 시공사례를 통하여 시공중의 제반문제점을 검토하여 이암층에서의 안전하고 합리적인 터널/암반사면의 시공방안에 대하여 고찰하였다.

• Proceedings of the KSEG Conference
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• 2001.03a
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• pp.3-14
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• 2001

암석은 외력하에서 탄성 및 점탄성적 변형거동을 보인다. 크리프 특성은 일정하중하에서 시간에 대한 암석의 변형으로 장기적인 지반거동을 예측할 수 있는 중요한 요소이며 암석의 점탄성적 성질을 반영한다. 포항지역에 분포하는 미고결 퇴적암인 이암을 대상으로 암석의 기본적인 물성, 역학적 특성 및 크리프 시험을 실시하였다. 일축압축강도의 40-70% 응력수준에서 순간탄성변형률은 하중의 증가에 대하여 선형적인 관계를 보였으며, 일차 크리프변형률은 시간경과에 대하여 로그함수로 적절히 설명되었다. 일차 크리프에서 이차 크리프로 진행하는 과정을 살피기 위하여 약 5일 이상의 시간이 필요하였으며 최종 크리프 변형에 의한 파괴시의 변형률은 약 0.01로 밝혀졌다.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.239-246
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• 2005

slaking 은 굴착에 의해 노출된 암반에서 발생하는 강도저하 및 입자간의 결합력 약화에 의해 암반이 세립화하는 현상이다. 이러한 slaking은 특히 퇴적암으로 구성된 암반사변의 안정성에 영향을 미치는 중요한 인자로 작용한다. slaking에 의한 암반사면의 불안정성은 신생대의 이질암이나 미고결 응회암에서와 같이 암반 자체의 강도 저하 및 결합력 약화에 의해 발생하는 붕괴현상과 차별풍화에 의해 이암 등이 급속도로 쇄굴 및 풍화되어 상부에 놓여 있는 암석이 낙석 등의 형태로 붕괴되는 현상으로 구분할 수 있다. 본 연구에서는 이암의 차별풍화에 의해 사면의 불안정성이 유발되는 연구지역을 대상으로 풍화 및 쇄굴 속도와 slake의 상관관계를 밝히고자하였다. 이를 위하여 slake test와 slake durability test를 수행하였으며 slake durability index를 획득하였다. 실험을 통해 획득된 slake durability index를 연간 쇄굴속도와 비교하여 상관관계를 검토하였으며 기존의 연구결과와 비교하여 slake durability index를 활용하여 쇄굴 정도를 예측할 수 있는 가능성을 제시하였다.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.100-109
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• 2004

Is this study, results of static pile load tests of in-situ cast piles in weak or uncemented sedimentary rock layers have been analyzed and presented. Consdierations on the characteristics of soils sedimentary rocks have been made. From the measurements of strain gauges and extensometers the relationship of unit skim friction versus displacement and that of unit end bearing versus displacement have been obatined to verity the characteristics of bearing capacity of this uncemented sedimentary rock layers. Also, a comparison has been made between ultimate skin friction in compression and tension.

• Journal of the Korean Geophysical Society
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• v.2 no.3
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• pp.201-208
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• 1999

A high-resolution seismic profile acquired across the middle part of the Pungam Basin, one of the Cretaceous sedimentary basins in Korea, has been interpreted to delineate subsurface geological structures. Boundary faults, intrusive bodies, and unconformity surfaces are identified on the seismic section. Basin fills are divided into five depositional units (Units I, II, III, IV, and V in descending order). The normal faults were formed by transtentional movement along a sinistral strike-slip fault zone. Unconsolidated sediments, a weathered layer, and sedimentary layers overly the Precambrian gneiss. The granite body intruded at the southeastern part contacts the adjacent sedimentary rocks by a near-vertical fault. Granitic intrusions caused tectonic fractures and normal faults of various sizes. An andesitic intrusive body indicates post-depositional magmatic intrusions. Continuous strike-slip movements have deformed basin-filling sediments (Units I and II).

• Journal of the Korean Geotechnical Society
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• v.28 no.7
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• pp.41-53
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• 2012

During rainfall period, to identify the characteristics of the infiltration of moisture, electrical resistivity monitering survey was carried out to weathered zone. Four regions of geophysical exploration areas with different rock types, four regions were selected. An area consists of mafic granite and three areas are composed of sedimentary rocks (Sandstone, Shale, Unconsolidated Mudstone). Survey was conducted from June (rainy season) to November (dry season), and during the period the change in resistivity was observed. According to the result of monitoring exploration on Geumjeong and Jinju areas, for the estimation of the standard rainfall, it is necessary to estimate the effects of the antecedent rainfall during the rainy season based on the overall rainfall from June till October and also necessary to consider this for the estimation of the half period. Also, the vertical distribution of the low resistivity anomaly zone does not show that the infiltration of moisture does not occur uniformly from the surface of the ground to the lower ground but shows that it occurs along the relaxed gap of the crack or soil stratum of the weathering zone. In Pohang area, the type of moisture infiltration is different from that of the granite or sedimentary rock. Since, after the rainfall, the rate of infiltration to the lower ground is high and the period of cultivation to the lower bedrock aquifer is short, it has similar effect to that of the antecedent rainfall applied for the estimation of the standard rainfall being presently used. In Danyang, due to the degree of water content of the ground, the duration period of the low resistivity anomaly zone observed in the lower ground of the place where clastic sedimentary rock is distributed is similar to that in Pohang area. The degree of lateral water diffusion at the time of localized heavy rain is the same as that of the sedimentary rock in Jinju. According to the above analysis results, in Danyang area, the period when the antecedent rainfall has its influence is estimated as three weeks or so.

• Clean Technology
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• v.26 no.1
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• pp.39-54
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• 2020

This study analyzed the groundwater quality according to the depth and geological features in Gyeongsangnam-do area using groundwater quality monitoring network data to grasp the groundwater quality characteristics and to provide basic data for policy making on efficient groundwater management. Five hundred and three data sets were acquired from background water quality exclusive monitoring network in soil groundwater information system for five years (2013 ~ 2017). Except for the total coliforms and tracer items such as mercury, phenol, and others, the parameters of water quality were significant or very significant, depending on depth and geological features. As the depth got deeper, the average value of pH and electrical conductivity increased; water temperature, dissolved oxygen, oxide reduction potential, arsenic, total coliforms, and turbidity decreased; and total unfit rate for drinking water standards was lower. It was found that the sum of the positive and negative ions was the highest in the clastic sedimentary rock and the lowest in metamorphic rock. The total unfit rate for drinking water standards was the highest for metamorphic rocks, followed by clastic sedimentary rock and unconsolidated sediments and, finally, intrusive igneous rock with the lowest penetration. The Na-Cl water type, which indicated the possibility of contamination by external pollutants, appeared only at some points in shallow depths and in clastic sedimentary rocks.

• Economic and Environmental Geology
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• v.41 no.1
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• pp.115-131
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• 2008

The aim of this study is to analyze relationships between topography/geology which affects physically groundwater regime and groundwater yield properties in Pohang City using Geographic Information System (GIS). For the purpose, topographic factors such as ground elevation, ground elevation difference, ground slope, and ground regional slope, and hydrogeologic unit, and groundwater yield properties factors such as transmissivity, specific capacity, and well yield, were constructed to spatial data base. Then the relationships between topography, geology and groundwater yield properties were analyzed quantitatively using GIS overlay technique. As the results, ground-water yield of unconsolidated sediments and porous volcanic rocks is the highest among the hydrogeologic units of study area, and clastic sedimentary rock is the lowest. There are positive relationship between the elevation and elevation difference and the groundwater yield properties and negative relationship between the topographic slope and the groundwater yield properties.

• Economic and Environmental Geology
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• v.38 no.5 s.174
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• pp.547-561
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• 2005

General characteristics of groundwater contamination by As were reviewed with several recent researches, and its occurrence in groundwater of Korea was investigated based on a ffw previous studies and a groundwater quality survey in Nonsan and Geumsan areas. In Bangladesh, which has been known as the most serious arsenic calamity country, about $28\%$ of the shallow groundwaters exceeded the Bangladesh drinking water standard, $50{\mu}g/L$, and it was estimated that about 28 million people were exposed to concentrations greater than the standard. Groundwater was characterized by circum-neutral pH with a moderate to strong reducing conditions. Low concentrations of $SO_4^{2-}$ and $NO_3^-$, and high contents of dissolved organic carbon (DOC) and $NH_4^+$ were typical chemical characteristics. Total As concentrations were enriched in the Holocene alluvial aquifers with a dominance of As(III) species. It was generally agreed that reductive dissolution of Fe oxyhydroxides was the main mechanism for the release of As into groundwater coupling with the presence of organic matters and microbial activities as principal factors. A new model has also been suggested to explain how arsenic can naturally contaminate groundwaters far from the ultimate source with transport of As by active tectonic uplift and glaciatiion during Pleistocene, chemical weathering and deposition, and microbial reaction processes. In Korea, it has not been reported to be so serious As contamination, and from the national groundwater quality monitoring survey, only about $1\%$ of grounwaters have concentrations higher than $10{\mu}g/:L.$ However, it was revealed that $19.3\%$ of mineral waters, and $7\%$ of tube-well waters from Nonsan and Geumsan areas contained As concentrations above $10{\mu}g/:L.$. Also, percentages exceeding this value during detailed groundwater quality surveys were $36\%\;and\;22\%$ from Jeonnam and Ulsan areas, respectively, indicating As enrichment possibly by geological factors and local mineralization. Further systematic researches need to proceed in areas potential to As contamination such as mineralized, metasedimentary rock-based, alluvial, and acid sulfate soil areas. Prior to that, it is required to understand various geochemical and microbial processes, and groundwater flow characteristics affecting the behavior of As.