• 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.

• The Journal of Engineering Geology
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• v.2 no.2
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• pp.173-200
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• 1992

The quality of groundwater in the central part of Taegu City is influenced by upstreams of Sin-stream and Beomeo-stream because the stream waters are main source of the groundwater, and chemical composition of the upstream waters has close relationship with andesite and monzonite in the igneous rock terrain. The pH of upstreams are weak acid ~ neutral in the igneous rock area and weak alkaline in the sedimentary rock area. Contents of $Ca^{2+}$ and $Mg^{2+}$ in the streams are apparently high, and $Na^{+}$ content is only slightly high in the sedimentary rock area. But $K^{+}$ content is lower in the Panyaweol formation area than in the monzonite area. The contents of heavy metals and $N0_3^{-}$ are also higher in the sedimentary rock area of residential sections and industrial complexes than those in the igneous rock area. The groundwater is contaminated in comparison to the upstream water of the igneous rock areas, and there are some differences in pollution level between the Panyaweol formation area of residential sections and the Haman formation area of industrial complexes. K, Na, Ca, Mg, Cl, $SO_4$ and $NO_3$ contents in the Haman formation area are relatively higher than those in the Panyaweol formation area. But pH is nearly equal in the two areas. The content of heavy metal ions is still lower than the drinking water standard of Korea and only slightly differs in the two sedimentary rock areas. But the groundwater in the Haman formation area is considerably contaminated by Kongdanstream and Dalseo-stream.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.652-661
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• 2006

The cut slopes in Jinju area constitute the Cretaceous Sedimentary rock which is one of the most poor ground conditions. The geological rocks of the cut slopes are correlated with Jinju Formation. Most of the rocks consist of Black Shale layer, but the lower parts consist of Alkorsic White Sandstone. So, It is characteristic of the differential weathering due to the difference of rock species. Moreover, vertical joints which concentrate on the released rock and weak rock fragments are accompanied with minor faults. We make out face mapping about each slopes through the detailed field-study and deduce RMR and SMR from the field data. The strength properties of rocks were obtained from references, indoor tests, and Back Analysis method. And, choosing properties were used in the stability analysis as stereographic projection and limit equilibrium analysis and we establish the countermeasures for the cut slopes.

• Journal of The Geomorphological Association of Korea
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• v.21 no.4
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• pp.1-17
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• 2014

This study analyzed characteristics of landform relieves on 12 bedrock whole(W) areas and 24 mountain(M) and valley(V) areas. Based on this result, characteristics and relations between bedrocks and landform relief were classified as follows. 1) gneiss-height M and granite-height W, M, V areas show active stream incision for uplift. However these areas have relatively low relief and grade compared to high altitude, because effect of denudation don't pass on whole slope. 2) gneiss-height W, V, gneiss-mid M, schist M, granite-mid M, volcanic rock W, M, sedimentary rock-height(conglomerate) W, M, V, sedimentary rock-mid (sandstone and shale) M, limestone W, M areas have active stream erosion and mass movement, but landform relieves are on the high side, because these have resistant bedrock and geological structure against weathering and erosion. 3) gneiss-mid W, V, schist W, V, granite-mid W, V, volcanic rock V, sedimentary rock-mid W, V, sedimentary rock-low(shale) M, limestone V areas landform relieves are on the low side, because these have weak resistance and active weathering, mass movement, erosion, transportation and deposit. 4) gneiss-low W, M, V, granite-low W, M, V, sedimentary rock-low W, V areas landform relieves are very low, because these don't have active erosion and mass movement as costal area with low altitude.

• Journal of the Korean earth science society
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• v.31 no.3
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• pp.205-213
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• 2010

A hydrochemical comparative study of groundwater in uraniferous sedimentary rock of the Ogcheon belt was carried out to investigate the genetic relationship between uraniferous groundwater of Daejeon area and uraniferous sedimentary rocks of the Ogcheon zone. The groundwater shows weak alkaline pH values rangingfrom 6.4 to 8.1 and low Eh values ranging from -50 to 225 mV. The groundwaters to Ca-$HCO_3$ type that shows high concentration of $Ca^{2+}$ and $HCO_3^_$ due to the dissolution of carbonate mineral in limestone. The concentration of uranium in the groundwater was measured very low below $3.2{\mu}g/L$, while it was detected as much as $1165{\mu}g/L$ in the mine waste water. The low Eh value of groundwater is one of the main causes of low uranium concentration of groundwater in uraniferous sedimentary rocks in the Ogcheon belt. It is suggested that the uranium of groundwater in granitic region of Daejeon area was not mainly provided from uraniferous sedimentary rocks in the Ogcheon belt.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.285-289
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• 2005

The Cenozoic Era consists of two period , the Tertiary and the Quaternary Period. Weak rock types may include areas containing: 1) poorly cemented or uncemented sediments, 2) highly weathered rock, or 3) fault lines. Especially this paper deal with poorly cemented or uncemented sedimentary rocks in slope. Mechanical weathering is caused by physical processes such as absorption and release of water, and changes in temperature and stress at or near the exposed rock surface. It results in the opening of discontinuities, the formation of new discontinuities by rock fracture, the opening of grain boundaries, and the fracture or cleavage of individual mineral grains. Decomposition causes some silicate minerals such as feldspars to change to clay minerals. There was a strong negative correlation between water absorption and important engineering properties such as strength and durability.

• Journal of the Korean Geotechnical Society
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• v.22 no.8
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• pp.63-72
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• 2006

In the ASTM and ISRM, an uniaxial compressive strength(${\sigma}_{c}$) has been estimated to be 23(ASTM) or $20{\sim}25$(ISRM) times of point load strength index using a diametral test regardless of the rock rating or geological conditions. This paper presents a relationship between $I_{s}$ and ${\sigma}_{c}$ of a weak sedimentary rocks on Ulsan of the Kyung-Sang Basin in Korea. In the results of 291 for ${\sigma}_{c}$ test and 2310 for $I_{s}$ test from 77 spots, the predicted errors of ${\sigma}_{c}$ determined by strength ratio of ${\sigma}_{c}/I_{s}$ have been relatively less than those determined by linear regression analysis. And in case of weak sedimentary rocks such as mudstones, shales and sandstones, ${\sigma}_{c}$ should be lower than those suggested by ISRM and ASTM.

• Tunnel and Underground Space
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• v.18 no.1
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• pp.20-32
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• 2008

The study shows a method called a square-inventory method, which is a better and faster method than scanline survey and window method for an analysis of slope stability. The study area is located in the Changri area, Boeun-Gun, Chungbuk, and consists of many formations of the Okcheon Supergroup. Various types of failure are observed from the phyllite including the rocks in the study area. The physical properties of meta-sedimentary rocks are that minerals of the rocks are composed of microcrystalline quartz and sericite, which are arranged parallel to bedding (or schistosity) and crenulation cleavage. Therefore, such properties affect geotechnical ones of the rock. The slope stability are analyzed by selecting 3 areas, each of which are divided into 2 or 3 slopes of $1m{\times}1m$ area that represent each of 3 investigation sites. The possibility of wedge and toppling failure is very high in all 3 areas by using square-inventory method. Although possibility of plane failure is weak in the investigation site 2, the plane failures are frequently found from the slope of site 2. The bedding (or schistosity) plane and cleavage, another types of discontinuity coexist in meta-sedimentary rocks uulike igneous rocks, and therefore are important factors to be considered together with joint structures in th ε analysis of slope stability.

• The Journal of Engineering Geology
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• v.29 no.3
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• pp.223-236
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• 2019

Resistivity surveys can identify the distribution of geological units and structures (including fragmented fault zones), the extent of weathered and modified geological strata, and the characteristics of groundwater. This study aims to analyze the underground sedimentary layers and geological structures near the Nari and Albong Basins of Ulleung-do, Korea, focusing on six survey lines to identify the spatial trends in subsurface resistivity. A modified dipole array method (D method) was employed, combining resistivity results obtained by existing dipole array methods (A and C methods). The modified method provides optimal analysis of the cross-section of underground resistivity, and shows a clear boundary between a low-resistivity zone (${\leq}500{\Omega}{\cdot}m$) of sedimentary layers and weak zones, and a high-resistivity zone (${\geq}5,000{\Omega}{\cdot}m$) of volcanic rock (trachyandesite). The estimated average thickness of the sedimentary layers is 50~100 m for the Albong Basin and 100~200 m for the Nari Basin. An anomaly zone, different from the weak zone in the bedrock, is identified as a caldera fault, and the low-resistivity zone extends from the surface down to the lowest survey depths.

• Journal of the Korean association of regional geographers
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• v.2 no.1
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• pp.39-49
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• 1996

There is a limestone basin surrounded by the mountains consisted of Paleozoic sedimentary and metamorphic rocks in the Masung, Munkyung city, Kyungsangpook do. The purpose of this paper is to elucidate the geomorphic processes of the gentle hillslopes in the marginal piedmont of Masung basin. To do so, I analyzed deposits over hillslopes and the relation ship between the distance from the divide and the height(above sea level) at the longitudinal profile of the hillslope, and considered interrelation between the distributions of the gentle hillslopes(less than 230m) and lithology. Geomorphic processes of Masung basin are as follow: (1) The depth of deposits over hillslope increases toward downstream of the hillslope. Most gravels within deposits, whose lithology is limestone, are those eroded at the boundary(overthrust fault zone) between the back-mountain and the hillslope. Deposits at the outward margin of hillslope is well sorted. and moderately imbricated. (2) Hillslope at the margin of the basin(160-230m asl) is formed by the action of 'the flow with channel'. At the boundary between the soft rock(limestone; basin floor) and hard rock(sedimentary and metamorphic rock; back-mountain), the relatively weak limestone is eroded to fresh bedrock by the subsequent action of the overland flow, and therefore discontinuity in slope appeared. (3) After hills lopes were formed, sediments(boulders and fine material) produced during dissection in back-mountain buried deposits over hillslope. In conclusion, geomorphic processes of Masung basin is 'differential erosion due to differentiation of lithological hardness' having suggested as geomorphic processes of granitic basin. However it is not 'removal of weathering material due to sheetflow' but 'erosion due to the overland flow with channel'.