• 자원환경지질
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• 제29권5호
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• pp.639-660
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• 1996

The lowest formation of the Cretaceous Gyeongsang Supergroup, the Nakdong Formation, unconformably overlies the gneiss complex basement in Hadong, Gyeongsangnam-do and Gwangyang, Chullanam-do. The Nakdong Formation of the study area is 500-600 m thick and occurs as a belt shape. Based upon lithology, sedimentary structure, and bedding geometry the formation consists of three conglomerate facies (Gd, Gn, Gic), five sandstone facies (Sh-n, Sh-i, Sp, Sr, Sm), and four mudstone facies (Mf, Mfn, Mc, Mv). Sandstone facies are the most prominent in the study area. The twelve facies can be grouped into five facies associations. The depositional settings are elucidated from analyses of 12 facies and five facies associations of the formation. The lower part of the Nakdong Formation was deposited in alluvial plain, and the middle and upper parts were in a riverine system. The lithologies of the Nakdong Formation of the Gyeongsang Basin have been considered to consist of generally conglomerates and pebbly sandstones that were accumulated in alluvial fans. But the common lithology of the study area is sandstone which was formed in lower part of alluvial fan or fluvial setting. It is supposed that the coarser sedimentary sequence distributed west to the study area should be eroded out after deposition and early uplift, and the finer sandstone sequence in the east remains behind. The mineral composition of sandstones and the clast composition of conglomerates indicate that the Nakdong Formation was derived mainly from the metamorphic source rocks. Some reworked intraclasts were also supplied from the intrabasinal sedimentary layers. Paleocurrent data collected from cross-beddings, ripple marks, asymmetric sand dune suggest that most sediments were transported from north to south during the Nakdong Formation time.

• 한국광물학회지
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• 제18권2호
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• pp.73-81
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• 2005

울릉분지 남부 대륙붕 석유탐사 시추공에서 회수된 사암 내에서 산출되는 녹니석-스멕타이트 혼합층 점토광물에 대하여 광물학적 및 화학적 연구를 수행하였다. X-선 회절분석과 화학분석 결과에 의하면 이 점토광물은 녹니석과 스멕타이트가 1:1 비율로 구성된 이팔면체형의 녹니석-스멕타이트 혼합층광물, 즉 토수다이트이다. 이 토수다이트는 Li가 풍부한 토수다이트로서 열수변질대에서 보고되는 토수다이트와 거의 동일하다. 이것은 토수다이트가 산출되는 지역은 열수변질과 관련된 열적 영향을 받았음을 지시한다. 실제로 이 시추공이 있는 지역은 단층과 습곡이 많이 발달되어 있고 구조적으로 변형되어 있다. 이와 같은 점을 고려할 때 하부로부터 열수가 올라와서 사암 내의 토수다이트의 생성에 기여했을 것으로 생각된다.

• 지구물리와물리탐사
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• 제13권4호
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• pp.388-396
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• 2010

이 논문은 전기비저항 관측을 이용한 이산화탄소($CO_2$)의 지중저장 모니터링 및 포화도 산정에 관한 실험 연구로, 균질한 시료 및 불균질한 시료에 대해 초임계$CO_2$와 염수의 주입 및 반복 실험을 통하여 전기비저항의 변화를 고찰하고 이로부터 전기비저항 지수를 이용하여 $CO_2$ 포화도를 추정하였다. 두 암석시료에 대해 실험한 결과, 시료 내부의 공극구조에 따른 영향과 함유된 점토 광물의 영향이 포화도 산출하는데 있어서 영향을 미치고 있음을 확인하였다. 이러한 결과는 실제 저류층에서의 전기비저항에 따른 $CO_2$ 포화도 추정의 정량적 평가에 있어 유용한 기초 자료가 된다.

• Geomechanics and Engineering
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• 제14권2호
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• pp.151-159
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• 2018

Annually, the global production of construction aggregates reaches over 40 billion tons, making aggregates the largest mining sector by volume and value. Currently, the aggregate industry is shifting from sand to hard rock as a result of legislation limiting the extraction of natural sands and gravels. A major implication of this change in the aggregate industry is the need for understanding rock fragmentation and energy absorption to produce more cost-effective aggregates. In this paper, we focused on incorporating dynamic rock and soil mechanics to understand the effects of loading rate and water saturation on the rock fragmentation and energy absorption of three different sandstones (Red, Berea and Buff) with different pore sizes. Rock core samples were prepared in accordance to the ASTM standards for compressive strength testing. Saturated and dry samples were subsequently prepared and fragmented via fast and dynamic compressive strength tests. The particle size distributions of the resulting fragments were subsequently analyzed using mechanical gradation tests. Our results indicate that the rock fragment size generally decreased with increasing loading rate and water content. In addition, the fragment sizes in the larger pore size sample (Buff sandstone) were relatively smaller those in the smaller pore size sample (Red sandstone). Notably, energy absorption decreased with increased loading rate, water content and rock pore size. These results support the conclusion that rock fragment size is positively correlated with the energy absorption of rocks. In addition, the rock fragment size increases as the energy absorption increases. Thus, our data provide insightful information for improving cost-effective aggregate production methods.

• Geomechanics and Engineering
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• 제24권2호
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• pp.179-191
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• 2021

In this study, the strength and failure mechanism of red sandstones with combined defects were investigated by uniaxial compression tests on red sandstones with different crack angles using two-dimensional particle flow code numerical software, and their mechanical parameters and failure process were studied and analyzed. The results showed that the mechanical characteristics such as peak strength, peak strain, and elastic modulus of the samples with prefabricated combined defects were significantly inferior than those of the intact samples. With increasing crack angle from 15° to 60°, the weakening area of cracks increased, elastic modulus, peak strength, and peak strain gradually reduced, the total number of cracks increased, and more strain energy was released. In addition, the samples underwent initial brittle failure to plastic failure stage, and the failure form was more significant, leading to peeling phenomenon. However, with increasing crack angle from 75° to 90°, the crack-hole combination shared the stress concentration at the tip of the crack-crack combination, resulted in a gradual increase in elastic modulus, peak strain and peak strength, but a decrease in the number of total cracks, the release of strain energy reduced, the plastic failure state weakened, and the spalling phenomenon slowed down. On this basis, the samples with 30° and 45° crack-crack combination were selected for further experimental investigation. Through comparative analysis between the experimental and simulation results, the failure strength and final failure mode with cracks propagation of samples were found to be relatively similar.

• 보존과학회지
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• 제33권6호
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• pp.399-416
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• 2017

라오스 '참파삭 문화경관 내 밧푸 사원과 고대주거지' 유적은 2001년 유네스코 세계문화유산으로 등재되었다. 현재 밧푸 주사원의 상부구조는 대부분 붕괴되어 있다. 또한 다양한 손상이 진행되고 있어 과학적이고 체계적인 진단을 통한 보존관리가 필요하다. 주사원은 사암과 벽돌을 주요 부재로 사용했으며, 균열과 탈락, 박리, 이격 등의 물리적 손상과 지의류, 선태류, 초본식물 등의 생물학적 손상이 심하다. 주사원의 석재를 대상으로 초음파 속도를 측정하여 물성을 평가한 결과, 주사원 동측면 사암의 풍화도지수는 0.10~0.74(평균 0.36)로 산출되어 중간풍화단계(MW)를 나타냈다. 남측면과 북측면은 평균 0.30와 0.32의 풍화도지수를 보여 상대적으로 높은 물성을 보였다. 주사원 기단의 경사도 분석결과, 남측면 4번 지점이 $5^{\circ}W$의 경사를 나타내 가장 큰 기울기를 보였으며, 이는 지반의 불안정에서 기인한 것으로 판단된다. 또한 상대적 수준측량 및 과거 측량도면을 검토할 때 주사원은 평지가 아닌 일정한 경사를 가진 지반에 자리한 것을 확인하였다. 남측면의 지반이 북측면에 비해 $1.51^{\circ}$ 더 기울어져 있는 것으로 보아 구조안정성에 영향을 미칠 것으로 보인다. 이격거리 분석 결과, 남측면 부재의 주요 이격은 평균 159.5 mm로 가장 큰 범위를 보이며, 상부로 올라갈수록 폭이 증가하여 가장 넓은 곳은 평균 328.3 mm를 나타냈다. 이와 같은 이격은 하부 지반의 부등침하에 따라 발생한 것으로 판단된다. 밧푸 주사원은 부분적으로 붕괴와 물리적 손상이 진행되어 건물의 구조안정성에 대한 지속적인 보존관리가 필요한 상태이다.

• 대한자원환경지질학회:학술대회논문집
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• 대한자원환경지질학회 2003년도 춘계 학술발표회 논문집
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• pp.315-315
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• 2003

Gold mineralization at Kyaukpahto occurs as stockworks/disseminations and locally as breccia zones in silicified sandstones of Lower to Middle Eocene Male Formation of Myanmar. The mineralization is spatially related with NNE -trending fracture zones_probably tensional open fractures caused by the right-lateral Sagaing fault system. Intensive silicification, sericitization, argillic alteration, sulfidation, and decalcification are recognized in the Kyaukpahto mine area. (omitted)

• 자원환경지질
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• 제8권4호
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• pp.203-210
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• 1975

The engineering properties of some Gyeongsang sedimentary rocks with respect to the grain size and the orientation of bedding planes were studied. The suitability of the rocks for civil and architectural construction was also investigated. The porosity of the rocks increases in proportion to the grain size. The ratio of the strain due to stress perpendicular to the bedding planes to the strain resulting from stress parallel to the bedding planes increases as the grain size decreases. The study indicates however, that the ratio of Young's modulus due to stress perpendicular to the bedding planes to Young's modulus resulting from stress parallel to the bedding planes increases in proportion to the grain size. The compressive strength of the sandstones studied is much greater than the strength of the conglomerate or shale. Only the coarse grained sandstone can be used for civil and architectural construction, regardless of the orientation of bedding planes. The relationships between compressive strength and density, elasticity and porosity, and compressive strength and mineral content were also studied.

• 지구물리와물리탐사
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• 제9권1호
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• pp.60-66
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• 2006

세 개의 서로 다른 사암 샘플들 -두 개의 합성 샘플과 한 개의 현장 샘플- 에 대해 현장 저류층의 대표적인 구속압력과 공극압력하에서 초음파 시험이 수행되었다. 세가지 사암 샘플들은 (a) 캘사이트 시멘트(calcite intergranula. cement (CIPS))로 만든 합성사암, (b) 실리카 시멘트(silica intergranular cement)로 만든 합성 사암 (c) Otway Basin 의 Boggy Creek 1 시추공에서 시도되는 $CO_2$ 파일럿 프로젝트의 대상 암석층 중 Waarre 층으로부터 추출한 코아 샘플로 구성되어 있다. 공극률은 각각 32%, 33%, 26%이다. 초기시험은 실내건조(room-dried) 상태에 있는 코아들에 대해 구속응력을 5 MPa 씩 단계별로 65 MPa 까지 증가시키며 이루어졌다. 그리고 나서 모든 코아들에 처음에는 온도 $22^{\circ}C$에서 6 MPa 공극압력으로 기체상의 $CO_2$를, 그 다음에는 온도 $22^{\circ}C$ 에서 7 MPa 부터 17 MPa 까지 5 MPa 씩 증가시키면서 액체상의 $CO_2$를 주입하였다. 구속응력은 10MPa부터 65 MPa까지 달리 하였다. P와 S 초음파 파형들이 유효응력이 증가할 때마다 기록되었다. 속도-유효응력 반응들이 P 파와 S 파에 대해 실험 자료들로부터 계산되었으며, 감쇠(1/Qp)들은 스펙트럼 비 방법을 이용하여 파형들로부터 계산되었다. 각각의 사암들에 대한 이론적인 속도-유효응력 계산은 $CO_2$ 압력-밀도 와 $CO_2$ 체적계수-압력 상 다이어그램(phasediagram), Gassmann 유효 매질 이론(effective medium theory)을 이용하여 구하였다. 기체상의 $CO_2$ 주입은 속도-유효응력에서 건조상태(공기로 포화된 상태)에 비해 거의 무시할만한 변화를 가져왔다. 다양한 공극압력에서 액체상의 $CO_2$ 주입은 공기로 포화된 상태에 비해 속도-유효응력 반응을 평균 약 8% 정도 낮게 한다. 실험자료들은 높은 유효응력에서 Gassmann 계산들과 일치한다. 이러한 이론과 일치하는 "임계" 유효응력은 사암의 종류에 따라 달라진다. 이 차이는 각각의 사암 종류의 미세구조에서 미세 균열 수의 차이에 기인한 것이라 생각된다. 높은 유효응력에서의 이론과 의미있게 일치하였으며, $CO_2$ 주입 시 현장에서의 탄성파 거동을 예상하는데 있어서 어느 정도 확신을 준다.

• Ocean and Polar Research
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• 제26권3호
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• pp.385-400
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• 2004

The Lago Sofia Conglomerate encased in the 2km thick hemipelagic mudstones and thinbedded turbidites of the Cretaceous Cerro Toro Formation, southern Chile, is a deposit of a gigantic submarine channel developed along a foredeep trough. It is hundreds of meters thick kilometers wide, and extends for more than 120km from north to south, representing one of the largest ancient submarine channels in the world. The channel deposits consist of four major facies, including stratified conglomerates (Facies A), massive or graded conglomerates (Facies B), normally graded conglomerates with intraformational megaclasts (Facies C), and thick-bedded massive sandstones (Facies D). Conglomerates of Facies A and B show laterally inclined stratification, foreset stratification, and hollow-fill structures, reminiscent of terrestrial fluvial deposits and are suggestive of highly competent gravelly turbidity currents. Facies C conglomerates are interpreted as deposits of composite or multiphase debris flows associated with preceding hyperconcentrated flows. Facies D sandstones indicate rapidly dissipating, sand-rich turbidity currents. The Lago Sofia Conglomerate occurs as isolated channel-fill bodies in the northern part of the study area, generally less than 100m thick, composed mainly of Facies C conglomerates and intercalated between much thicker fine-grained deposits. Paleocurrent data indicate sediment transport to the east and southeast. They are interpreted to represent tributaries of a larger submarine channel system, which joined to form a trunk channel to the south. The conglomerate in the southern part is more than 300 m thick, composed of subequal proportions of Facies A, B, and C conglomerates, and overlain by hundreds of m-thick turbidite sandstones (Facies D) with scarce intervening fine-grained deposits. It is interpreted as vertically stacked and interconnected channel bodies formed by a trunk channel confined along the axis of the foredeep trough. The channel bodies in the southern part are classified into 5 architectural elements on the basis of large-scale bed geometry and sedimentary facies: (1) stacked sheets, indicative of bedload deposition by turbidity currents and typical of broad gravel bars in terrestrial gravelly braided rivers, (2) laterally-inclined strata, suggestive of lateral accretion with respect to paleocurrent direction and related to spiral flows in curved channel segments around bars, (3) foreset strata, interpreted as the deposits of targe gravel dunes that have migrated downstream under quasi-steady turbidity currents, (4) hollow fills, which are filling thalwegs, minor channels, and local scours, and (5) mass-flow deposits of Facies C. The stacked sheets, laterally inclined strata, and hollow fills are laterally transitional to one another, reflecting juxtaposed geomorphic units of deep-sea channel systems. It is noticeable that the channel bodies in the southern part are of feet stacked toward the east, indicating eastward migration of the channel thalwegs. The laterally inclined strata also dip dominantly to the east. These features suggest that the trunk channel of the Lago Sofia submarine channel system gradually migrated eastward. The eastward channel migration is Interpreted to be due to tectonic forcing imposed by the subduction of an oceanic plate beneath the Andean Cordillera just to the west of the Lago Sofia submarine channel.