• Geotechnical Engineering
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• v.13 no.6
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• pp.13-24
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• 1997

In Korea, granite is abundant and occupies around two-thirds of the country's ground. Bven though weathered granite residual soils are widely distributed, undisturbed sampling of this soil is extremely difficult because of the particultate structure. This difficulty has kept away the researchers from investigating !he deformational characteristics of weathered granite residual soil. Thus, a special undisturbed sampling device was developed and undisturbed samples were prepared for triaxial compression (TX), resonant column(RC), and torsional shear (75) tests. Local deformation transducer (LDT) was fabricated for internal strain measurements during TX tests. Both undisturbed samples and statically compacted samples of same density were tested by using TX with LDT, RC, and 75 test equipments. The behaviour of statically compacted specimens was almost the same as that of undisturbed samples in the strain ranges below 1 percent. The stiffness and strength decreased with increasing degree of weathering. In case of undisturbed specimens, strains at failure are widely varied from 2 percent to 11 percent, and planes of failure are irrelevant to the angle of internal friction due to the inhomogeneous nature.

• Journal of the Korean Geotechnical Society
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• v.35 no.12
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• pp.15-24
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• 2019

Weathered granite zone exists in most regions of Korea and it is often used as a bearing stratum of geotechnical structures. So it is very important to estimate the characteristics of weathered granite zone. SPT (Standard penetration test) is usually performed to investigate the characteristics of the weathered zone because undisturbed samples suitable for laboratory testing are hardly retrieved. PMT (Pressuremeter test) can reliably evaluate the in situ stress-strain behavior, but it is rarely conducted because of their high cost and time-consuming procedure. In this study, the correlation between the SPT-N values and the PMT results, obtained from the weathered granite zone, was analyzed. Empirical equations for pressuremeter modulus (E_m) and limit pressure (P_L) were suggested and compared with the previous research.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2006.09a
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• pp.59-79
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• 2006

The successful execution of shield tunnelling depends on the cutting ability of cutter. So the selection of shape, size and material of cutter according to geology condition is important work. Since shield tunnelling method was first invented in 1881, the cutting tool for rock has been developed owing to various experiments and researches, the study for soil, however, is insufficient. This paper introduces the shield tunnelling that will be carried out on weathered rock section (920m) of Seoul Subway Line 7 Extension C703. The shape and the material of cutter are discussed required for execution without replacement of cutter tool as well as for advance of excavation efficiency. In addition the estimation method of cutter abrasion in case of excavation on weathered soil is proposed and verified. Specially, the coefficient of abrasion for different soil and cutter is proposed by means of investigation into construction example of foreign country.

• Journal of Conservation Science
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• v.8 no.1 s.11
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• pp.1-9
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• 1999

The present aspect of the Seoggulam is the result of natural weathering of the rocks and influences by mankind. The rocks constituting the Seoggulam is granodiorite of medium and coarse grains which show brown to dark brown weathered surface resulted mainly from chemical weathering of feldspars. It also shows partly milky white or black colors due to influences by weathering products of cement used in the concrete dome and cracks. There are cracks and crack zones with very small cracks which may be formed by strong weathering and influences of shocks during operations of reconstitution and repair. However, for the better conservation, it must be considered to maintain the balances of temperature and moisture, especially relative moisture in places within the room, structural stability, and the influences of vibration made up by some reasons.

• Journal of Conservation Science
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• v.19
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• pp.57-66
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• 2006

The rock consisting the Naju-Dongmunoi-Seogdanggan (Stone Stele)(Treasure number 49) is biotite granite of medium to coarse grains which might be taken from nearby area. The rock is mainly composed of quartz, plagioclase, alkali feldspar and biotite. Due to strong weathering grail peel-off and surface exfoliation are well developed. The rock surface is changed into pale brown or pale black colors according to weathering, organism and weathering product of iron band. Major deterioration phenomena are grain peel-off, surface exfoliation, cracks and damage which may be originally classified into weathering, effect of weathering product of iron band, organisms, structural unstabilities and impact.

• The Journal of Engineering Geology
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• v.20 no.4
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• pp.461-465
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• 2010

Weathering and permeability in rocks play a very important role in underground disposal of radioactive waste and their long-term management as well as stability security of rock structures. Weathering and permeability of rocks are largely controlled by the characters of inner structures of rocks. In other words, weathering rate can be accelerated depending on the quantity of pore and microcrack in rocks. Quantitative evaluation of inner structures of rocks can serve as a tool that can assess the degree of weathering of rocks. Therefore it can be said that the understanding of three dimensional distribution of the inner structure of rocks is important for long-term management of rock structures. This study was performed to analyze three dimensional distribution of pore in rocks using Micro Focus X-ray CT on fresh granite and weathered granite from Korea. Results of the analysis clearly show distribution of pore and porosity of the inner rock.

• Journal of the Korean Geographical Society
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• v.50 no.5
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• pp.505-514
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• 2015

This study analyzes a correlation between water content values and chemical index of alteration (CIA) for coarse sedimentary rocks of Mt. Cheonsaeng in Gumi-si, Kyeongsangbuk-do. Through measurement of various water values of 20 samples including water content rate, water absorption rate and equipment measuring we comparatively analyzed the values with CIA of the samples obtained by X-ray fluorescence. As a result of analysis water content rate and water absorption rate in a sedimentary rock are likely to be higher when matrix is psephitic and less compact. Furthermore the higher water content rate is, the higher CIA is due to increase of $SiO_2$ and $Al_2O_3$ and decrease of CaO and $Na_2O$ derived by chemical weathering of felspar. This correlation between water content rate and CIA represents a similar result with previous studies targeting granite.

• Journal of the Korean earth science society
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• v.36 no.6
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• pp.543-552
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• 2015

This study examines the processes of rock weathering and tafoni formation targeting tafoni at Mt. Cheonsaeng, Gumi-si, Gyeongsangbuk-do. In the study area, a frequency of tafoni is high in conglomerate and conglomeratic sandstone among regional sedimentary rocks, which means that an initial stage of the formation begins a breakaway of gravel from bedrock and also exfoliation from rock surface. Geomorphologically tafoni have intensively been developed at the southfacing slope with exposed rocks, which means that its formation was favorably controlled by environmental conditions including strong influences of mechanical weathering in winter and chemical weathering in summer times. The results of measuring water content at a tafoni-bearing rock surface using GIS interpolation analysis indicate that moisture rate in/around tafoni is higher than the periphery. Thus, it is considered that moisture distribution at a rock surface plays a role in its formation. Analysis of percipitation and secondary minerals induced by chemical weathering is in progress.

• The Journal of Engineering Geology
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• v.14 no.4 s.41
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• pp.381-390
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• 2004

This study was performed to relate the weathering properties of Oyaish tuff from Japan to mechanical properties of rocks in terms of mineralogical alteration and chemistry. The tuff is composed of clinoptilolite, quartz, feldspars, mordenite, opal C-T, and smectite. Since fresh tuff contains approximately $30\~50\%$ zeolite, it is expected that the rock is subjected to weathering process ascribed to water contents on earth surface, significantly reducing mechanical strength of tuff. It is also anticipated that weathering process and properties may be different even in the same rock mass, due to the differences in local mineralogy, chemistry and microtextures in tuff.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.7182-7188
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• 2015

Recently, to improve manual mapping method, digital mapping using high-resolution camera and laser scanner has increasingly attracted attention and the relevant study is reportedly on the rise. In this study, laboratory and field test which are intended to quantitatively analyze and estimate the weathering degree which is one of the engineering characteristics of tunnel face using laser scanner that integrates high-solution imaging technique have been conducted. In a bid to analyze correlation between reflectance of laser scanner and weathering degree, investigation of the factors influencing on reflectance was carried out. And to minimize the effect on RGB value which is one the critical influential factors on reflectance, modification equation obtained from lab test was proposed. Modification equation proposed in this study was verified by comparing the values before and after correction using the data obtained by scanning. Consequently, weathering index estimated by modified reflectance appeared very similar with dominant weathering degree and weathering ratio monitored at the field.