| Engineering geological feasibility study is a key stage to high-dam construction. Its research findings may have decisive influence on decision-making. Objectives of this research are to evaluate the strength stability and deformation stability of engineering buildings and rock mass within range of influence.In terms of main principles of Dynamic Geo-historical Course Analysis and Systems, field site at Nuozhadu hydropower station, Langcangjiang River, Yunnan Province is investigated in detail.Based on the in situ measured data and numerical modeling results, the research are mainly composed of four parts. Included are: (1) Engineering geological conditions, rock mass mechanical environment and it's hydraulic parameters at research area. (2) Assessment of rock mass quality and determination of their corresponding mechanical parameters. (3) Study of Geological Engineering Mechanical Model(GEMM). (4) Evaluation of feasibility of planned dam types in course of dam construction and after storage.The main findings of this research are as follows:The researching theory and method system of engineering geological feasibility study of high-dam construction are summarized in this thesis. Furthermore, the study process has been divided into five stages, namely are planning, comparison of dam section, comparison of dam site, comparison of dam axes and special-purpose engineering study. Each stage has its own research objectives and key decisive factor. The whole researching process of engineering geological feasibility is a step by step course from merely considering geological factors to taking the interaction between geological environment and engineering into account.The concept of GEMM (Geology-Engineering-Mechanic Model) has been proposed in this thesis. GEMM is a parameterized model consisted of representative units, boundary units (including natural boundary and artificial boundary), target parameters and key engineering information. It is a kernel and belt in the process of geological feasibility evaluation because it is not only integration of generalized geological conditions and engineering information but also basis of further theoritical analysis and numerical modeling. As an example, A GEMM has been built in combine with the research practice of research area.The formation mechanism of complex rock mass at research area is probed. Research shows that four factors have great influence on the formation of complex rock mass. First, rock mass subjected six times of tectonic movement during long period of geo-history, each tectonic movement produced fractures and associated joints corresponding to the orientation of maximumprincipal stress and deteriorated the properties of fractures formed at former period(s). Second, down-cutting of Langcangjiang River produced unloading fractures. Third, the upheaval of Yakou Vault produced a serial of radial tensile fractures which located xm right-bank side, thus, degraded the rock mass structure of right-bank. Fourth, the intersection and convergence of all these fractures formed a fracture net which served as good channel for all kinds of weathering forces, especially ground water, enter into deep inner part of rock mass. Under the combined action of above-mentioned four factors, the complex rock mass at right bank which consist of two weak rock mass bands and superficial unloading relaxed rock mass came into being.Quality of rock mass has been accomplished by using four kinds of assessment method. Zone maps show that rock mass quality generally has the tendency which decedent with elevation, however, the change of rock mass quality is not gradual but has "skips" at some positions. This manner of change reflected the great influence of texture to rock mass quality.Rock mass mechanical parameters corresponding to individual rock mass quality at different levels are determined by means of correlation analysis and statistical analysis. Results show that calculation outcomes match well with measured mechanical parameters. Thus, mechanical parameter...
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