• Title/Summary/Keyword: Sedimentary Rock

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Physical Properties and Friction Characteristics of Fault Cores in South Korea (단층핵의 물리적 특성과 마찰 특성의 상관관계 분석)

  • Moon, Seong-Woo;Yun, Hyun-Seok;Seo, Yong-Seok
    • Economic and Environmental Geology
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    • v.53 no.1
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    • pp.71-85
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    • 2020
  • To understand behavior of fault cores in the field of geotechnical and geological engineering, we present an investigation of the physical properties (breccia and clay contents, unit weight, porosity, and water content) and friction characteristics (internal friction angle and cohesion) of fault cores, in granitic, sedimentary, and volcanic rocks in South Korea. The breccia contents in the fault cores are positively correlated with unit weight and negatively correlated with clay content, porosity, and water content. The inter-quartile ranges of internal friction angles and cohesion calculated from direct shear tests are 16.7-38.1° and 2.5-25.3 kPa, respectively. The influence of physical properties on the friction characteristics of the fault cores was analyzed and showed that in all three rock types the internal friction angles are positively correlated with breccia content and unit weight, and negatively correlated with clay content, porosity, and water content. In contrast, the cohesions of the fault cores are negatively correlated with breccia content and unit weight, and positively correlated with clay content, porosity, and water content.

Design on the large section of station tunnel under shallow overburden (저토피고 대단면 정거장터널의 설계)

  • Jeong, Yun-Young;Choi, Hae-Joon;Kim, Byung-Ju;Yu, Bong-Won;Kim, Yong-Il;Oh, Sung-Jin
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.9 no.2
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    • pp.171-182
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    • 2007
  • For minimizing the effect on the focus of civil traffic and environment conditions related to the excavation at the traffic jamming points, an underground station tunnel was planned with 35.5 m in length and bigger area than $200\;m^2$ in sedimentary rock mass. It faced the case that the overburden was just under 13 m. Not based on a pattern design but on the case histories of similar projects and arching effect, the design of large section tunnel under shallow overburden was investigated on three design subjects which are shape effect on the section area, application method of support pressure, and supporting and tunnel safety. According to the mechanical effect from section shape, a basic design and a preliminary design was obtained, and then supporting method of large section was planned by the supporting of NATM and a pipe roof method for subsidence prevention and mechanical stability. From the comparative study between both designs, it was found that the basic design was suitable and acceptable for the steel alignment of tunnel lining, safety and the design parameter restricted by the limit considered as partition of the excavation facilities. Through the analysis result of preliminary design showing the mechanical stability without stress concentration in tunnel arch level, it also was induced that shape effect of the large section area and yielding load obtained from deformation zone in the surrounding rock mass of tunnel have to be considered as major topics for the further development of design technique on the large section tunnel.

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Geochemical Characteristics of Devonian Cairn Formation in Alberta, Canada (캐나다 알버타 지역의 데본기 Cairn층의 지화학적 특성 연구)

  • Park, Myong-Ho;Kim, Ji-Hoon;Lee, Sung-Dong;Choi, Ji-Young;Kil, Yong-Woo
    • Economic and Environmental Geology
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    • v.43 no.2
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    • pp.85-100
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    • 2010
  • Devonian Cairn Formation is one of the important hydrocarbon reservoirs in Alberta, Canada. However, the Cairn Formation, outcropped in the study area, is not prospective reservoir with poor porosity and permeability by some late diagenetic processes. In this study, geochemical characteristics of the Cairn Formation were studied to use these preliminary results for advanced geological and geophysical petroleum explorations in the near future. Rock-Eval pyrolysis showed that total organic carbon content is less than 0.3 wt.%, indicating a minor amount of bitumen and/or other hydrocarbons. The carbonates in the Cairn Formation are mainly composed of subhedral and anhedral dolomites. Pore sizes in the carbonate are various, ranging from nanometer to micrometer. Clastic sediments increase in the upper and lower parts of the Cairn Formation, probably due to changing its depositional conditions. The Cairn Formation can also be divided into several intervals based on Ca/Mg ratio in dolomite and degree of amount of calcite. These could be formed by different sedimentary environment, degree of cementation and recrystallization, different saline/fresh water, etc.

Relative Movement of Major Elements on the Weathering of Rocks (암석의 풍화에 따르는 주요성분의 상대적 이동)

  • Nam, Ki-Sang;Cho, Kyu-Seong
    • Economic and Environmental Geology
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    • v.26 no.1
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    • pp.67-81
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    • 1993
  • This dissertation is a basic research on the degradation of rocks and aims at clarifying the relations between the progression of degree of weathering and the variation of chemical composition. The author wants to make clear the degradation of rocks and the process of formation of sedimentary rocks from a standpoint of elucidation of migration of elements. This study is considered to be significant not only as a part of research on the distribution of earth crust materials but as the petrogenesis of rocks. The chemical studies on the weathered rocks have been started relatively early and there are not a few researches on them: Goldich, 1938; Harris, et al., 1966; Ruxton, 1968; Berner, et al., 1982; Kanuss, 1983; Lasaga, 1984; Siagel, 1984. The degree of migration of elements in weathering is the composite result of various factors. Because, at the present time, it is difficult to clarify the individual and composite effects of each factor theoretically and quanititatively, we must accumulate empirical data and use them relatively. In such consideration the author acquired some data of chemical weathering from the chemical analysis of granitic and basaltic rocks in and around Fukuoka city, Japan and granitic rocks in and around Chonju and Iri cities, Korea. Because both rock types studied can be considered as representative materials of acidic and basic rocks compsing the earth crust, it is significant to examine the phenomena of weathering of both rock types. The following results are obtained from the analysis and examinations of chemical compositions of the original and weathered rocks. The loss rate of major elements has no uniformity, but the following relation holds in general; Ca, Na> K, Si> Mg> Fe, Al. As weathering proceeds, the ratio of $Al_2O_3/CaO$ shows increasing phenomena, and that of $Na_2O/CaO$ decreasing. The range of migration of composition is broad in basaltic rocks but narrow in granitic rocks. The reason is that the chemical weathering of basaltic rocks progresses more easily than that of granitic rocks. The chemical weathering potenitial index of basaltic rocks in larger than that of granitic rocks. The reason is that the chemical weathering of basaltic rocks proceeds more easily than that of granitic rocks. In weathering, the decrease of mobile cations such as $Ca^{2+}$, $Na^{2+}$, $Mg^{2+}$ and the increase of $H_2O$ in basaltic rocks are more obvious than in granitic rocks.

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Petrological Characteristics of the Satkatbong Pluton, Yeongdeok, Korea (영덕 삿갓봉암체의 암석학적 특성)

  • Lim, Hoseong;Kim, Jung-Hoon;Woo, Hyeondong;Do, Jinyoung;Jang, Yun-Deuk
    • The Journal of the Petrological Society of Korea
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    • v.25 no.2
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    • pp.121-142
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    • 2016
  • The Satkatbong pluton was studied with other plutons together, but some fundamental petrological characteristics were missing. This study mainly reports the petrography and geochemistry of the Satkatbong pluton comparing with the Daebo and the Bulguksa granitoids in south Korea. The Satkatbong pluton, which is host rock including a number of Mafic Magmatic Enclaves (MME), is north-south shaped dioritic pluton, located along the east coast of south Korea. The Satkatbong pluton seems to be unconformable with Cretaceous sedimentary rocks from fieldwork result. In geochemistry, the Satkatbong pluton, which is roughly similar with the Daebo granitoids, is classified into calc-alkali series rock and volcanic arc granitoid Tectonically. The fact that AlT value in marginal parts of amphiboles in the Satkatbong pluton is lower than other granitoids implies emplacement depth of the Satkatbong pluton was relatively shallow. The Satkatbong pluton shows different geochemical feature compared to the adjacent adakitic Yeongdeok granite. This seems to be caused by mafic mantle material expected from the occurrence of MMEs.

A Fundamental Study on the Potential of Alkali-Aggregate Reaction according to KS F 2545 and ASTM C 1260 Test Methods (KS F 2545와 ASTM C 1260 시험법에 따른 알칼리골재 잠재가능성에 관한 연구)

  • Baek, Chul-Seoung;Seo, Jun-Hyung;Kim, Young-Jin;Cho, Kye-Hong;Kim, Kun-Ki;Lee, Jin-Young
    • Resources Recycling
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    • v.29 no.2
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    • pp.18-27
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    • 2020
  • Chemical experiment KS F 2545 and Physical experiment ASTM C 1260 has been accomplished to estimate the potential of alkali aggregate. Used for testing aggregate samples are forest aggregate and recycled aggregate which collected in Gangwon province Samcheok and Pyeongchang, Jeollabuk province Gimje and Kochang, and Gyeongsangnam province Goryeong. As the results of chemical experiment confirmed that if silicate rock and carbonate rock are mixed, reduction in alkalinity is increase. So it has been identified that case makes a disturb at the result of alkali aggregate reaction. In 9 out of the 62 aggregate samples check dissolved silica exceeding 100 mmol/ℓ. and mortar bar length increase rate confirmed that 5 of 9 chemical method aggregates were 0.1~0.2% and 2 aggregates were 0.2%. As a result of the alkaline aggregate reaction test using the chemical method and the mortar bar method, the aggregates showing alkali aggregate reaction are sandstone and tuff aggregates. Therefore, Alkali aggregate reaction tests are required to use clastic sedimentary rocks and volcanic pyroclastic rocks aggregates.

Clay Mineral Composition of the Soils Derived from Residuum and Colluvium (잔적 및 붕적모재 토양의 점토광물 특성구명)

  • Zhang, Yong-Seon;Sonn, Yeon-Kyu;Jung, Sug-Jae;Lee, Gye-Jun;Kim, Myung-Sook;Kim, Sun-Kwan;Lee, Ju-Young;Pyun, In-Hwan
    • Korean Journal of Soil Science and Fertilizer
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    • v.39 no.5
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    • pp.245-252
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    • 2006
  • This experiment was conducted to investigate the distribution and compositions of clay mineral and to replenish the soil classification system in Korea. Soil layer samples were collected from 26 residuum and colluvium soil series out of 390 soil series in Korea, and then analyzed for soil physical and chemical characteristics, mineral and chemical compositions of clay in B horizon soils. Major clay minerals of residuum and colluvium were illite and chlorite in soils originated from the sedimentary rock such as limestone, shale, sandstone and conglomerate; quartz and kaolin in soils originated from rhyolite, neogene deposits, porphyry and tuff; and kaolin and quartz in the soils originated from granite, granite gneiss and anorthosite. Clay minerals in Korean soils were divided into 4 groups: mixed mineral group(MIX) mainly contained with illite, kaolin and vemiculite; kaolin group(KA) with kaolin and illite; chlorite group(CH) with chlorite and illite; and smectite group(SM) with kaolin, illite and smectite. The most predominant clay mineral group was kaolin group(KA) with kaolin and illite; an mixed mineral group(MIX) with illite, kaolin and vemiculite. Cation exchange capacity (CEC) of clay was low in the soils mainly composed with MIX and KA groups and silica-alumina molar ratio of clay was high in the soils composed with SM group

A Pilot Test for the Utilization of Road Subsoil of the Tertiary Mudstone in Pohang Basin (포항분지 제3기 이암의 도로 노체 활용을 위한 현장시험)

  • Gong, Jeong-Sik;Baek, In-Woo;Kim, Jae-Gon;Song, Young-Suk;Kim, Tae-Hyung
    • Journal of the Korean Geosynthetics Society
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    • v.20 no.3
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    • pp.1-10
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    • 2021
  • The purpose of this study is to present the possibility a utilization of the tertiary mudstone in Pohang as road subsoil material through pilot experiments on the road embankment structure. This mudstone is an unconsolidated rock that is distributed in the soft rock sedimentary layer, the tertiary layer of the Cenozoic, and causes physical problems such as slaking, swelling, and reduced shear strength and chemical problem like acid drainage. In order to solve various complex problems, an laboratory mixing test was conducted, and the optimal mixing conditions of the tertiary mudstone (90%), composite slag (steel making 70%, blast furnace 30%), and neutralization and coating agent treatment were derived. In order to prove its utilization, a real-scale road embankment structure was constructed and tests were conducted for each section. The pre-processing section is stable due to the design of optimal mixing conditions, while in post-processing section, natural weathering proceeded rapidly, and structural problems were concerned. Since the effect of neutralizing and coating agents was confirmed in temporary-staking section, the neutralizing and coating agents can be applied during the temporary storage period.

Impact of pore fluid heterogeneities on angle-dependent reflectivity in poroelastic layers: A study driven by seismic petrophysics

  • Ahmad, Mubasher;Ahmed, Nisar;Khalid, Perveiz;Badar, Muhammad A.;Akram, Sohail;Hussain, Mureed;Anwar, Muhammad A.;Mahmood, Azhar;Ali, Shahid;Rehman, Anees U.
    • Geomechanics and Engineering
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    • v.17 no.4
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    • pp.343-354
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    • 2019
  • The present study demonstrates the application of seismic petrophysics and amplitude versus angle (AVA) forward modeling to identify the reservoir fluids, discriminate their saturation levels and natural gas composition. Two case studies of the Lumshiwal Formation (mainly sandstone) of the Lower Cretaceous age have been studied from the Kohat Sub-basin and the Middle Indus Basin of Pakistan. The conventional angle-dependent reflection amplitudes such as P converted P ($R_{PP}$) and S ($R_{PS}$), S converted S ($R_{SS}$) and P ($R_{SP}$) and newly developed AVA attributes (${\Delta}R_{PP}$, ${\Delta}R_{PS}$, ${\Delta}R_{SS}$ and ${\Delta}R_{SP}$) are analyzed at different gas saturation levels in the reservoir rock. These attributes are generated by taking the differences between the water wet reflection coefficient and the reflection coefficient at unknown gas saturation. Intercept (A) and gradient (B) attributes are also computed and cross-plotted at different gas compositions and gas/water scenarios to define the AVO class of reservoir sands. The numerical simulation reveals that ${\Delta}R_{PP}$, ${\Delta}R_{PS}$, ${\Delta}R_{SS}$ and ${\Delta}R_{SP}$ are good indicators and able to distinguish low and high gas saturation with a high level of confidence as compared to conventional reflection amplitudes such as P-P, P-S, S-S and S-P. In A-B cross-plots, the gas lines move towards the fluid (wet) lines as the proportion of heavier gases increase in the Lumshiwal Sands. Because of the upper contacts with different sedimentary rocks (Shale/Limestone) in both wells, the same reservoir sand exhibits different response similar to AVO classes like class I and class IV. This study will help to analyze gas sands by using amplitude based attributes as direct gas indicators in further gas drilling wells in clastic successions.

Content Analysis of the Mesozoic Geology of the Korean Peninsula in Earth Science II Textbooks: Focusing on Consistency within and among Textbooks, and with Scientific Knowledge (지구과학II 교과서의 한반도 중생대 지질 내용 분석: 교과서 내·교과서 간·과학 지식과의 일치 여부를 중심으로)

  • Jung, Chanmi;Yu, Eun-Jeong;Park, Kyeong-Jin
    • Journal of the Korean earth science society
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    • v.43 no.2
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    • pp.324-347
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    • 2022
  • Geological information on the Korean Peninsula plays a significant role in science education because it provides a basic knowledge foundation for public use and creates an opportunity to learn about the nature of geology as a historical science. In particular, the Mesozoic Era, when the Korean Peninsula experienced a high degree of tectonic activity, is a pivotal period for understanding the geological history of the Korean Peninsula. This study aimed to analyze whether content regarding the geology of the Mesozoic Era are reliably and consistently presented in the 'Geology of the Korean Peninsula' section of Earth Science II textbooks based on the 2015 revised curriculum. Four textbooks for Earth Science II were analyzed, focusing on the sedimentary strata, tectonic movement, and granites of the Mesozoic Era. The analysis items were terms, periods, and rock distribution areas. The consistency within and among textbooks and of textbooks and scientific knowledge was analyzed for each analysis item. Various inconsistencies were found regarding the geological terms, periods, and rock distribution areas of the Mesozoic Era, and suggestions for its improvement were discussed based on these inconsistencies. It is essential to develop educational materials that are consistent with the latest scientific knowledge through collaboration between the scientific and educational communities.