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Title: Weathering and geotechnical characterization of Korean granites
Author: Lee, Su Gon
Awarding Body: Imperial College London (University of London)
Current Institution: Imperial College London
Date of Award: 1987
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The objectives of this research are twofold, namely (1) to investigate the relationship between the weathering of granite and factors such as climate, geological structure, geomorphology, and age: (2) to measure and interpret the geotechnical behaviour of the Jurassic and Cretaceous granites in South Korea. The thesis consists of four parts; Part I presents the general description of the research objectives, location and regional geology of the study area, and reviews of the weathering of granite and the influence of weathering on the engineering properties of granite. The research approach is outlined in Part II and the nature of existing data and method of investigation are also described. This is followed by a detailed description of the study areas and sites. Part III analyses and discusses the results obtained in the field and laboratory studies. In Part IV, the integrated results from this research are summarised with conclusions and recommendations. Five granitic terrains (Seoul, Kwanak, Palgong, Eonyang and Pusan) were selected for the study after careful evaluation of existing information. Generally the weathering of these Korean granites is dependent on the local geomorphology, extensive fracturing by faults and joints, zones of alteration associated with hydrothermal alteration/mineralisation, the presence of basic dykes and, on a more local scale, minor faults. The overall weathering of Koreangranites is rather gradual, seldom showing a core stone development. The weathering profile is also found to be much deeper (extending down to 30 m ) in the medium grained Cretaceous granites than in the coarse grained Jurassic granites (where it extends to 20 m ). Seismic refraction surveys were conducted across the top of vertical exposures to determine the suitability of the technique for identifying the depth of weathering at the respective locations. The results showed that the boundaries of weathering grades could be predicted to within 2 m of that identified visually. The existing criteria for the weathering description and classification of granite as a rock material and of its mass is based on the degree of rock discolouration, the presence or absence of the original rock texture and the soil-rock ratio. These criteria were examined critically when applied to the Korean granite and were consequently amended to include quantitative index values. In order to understand the influence of weathering on the geotechnical properties of Korean granite, an intensive programme of laboratory and field tests was conducted on typical specimens of each weathering grade, as follows: C 1 ) six types of field index test: Schmidt hammer, point load strength, hand penetrometer, tilt test and simple tests of slaking and permeability. C 2 ) nine types of laboratory index test: natural and saturated moisture content, quick absorption, specific gravity, density, consistency limits, particle size analysis, p - wave velocity andslake durability: ( 3 ) three types of engineering design test: unconfined compressive strength, deformability and direct shear box. (Permeability was not measured but existing information on its typical values for Korean granite was collected and used). From these tests it can be concluded that most of the index values are very sensitive to change in weathering grade. Engineering design tests indicate that the unconfined compressive strength is significantly reduced and that the rock becomes ductile with increasing weathering grade and saturation.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Geology