Dam Foundation Rock Mass Quality Classification Of Meng Di Gou Hydropower Station

In the process of hydropower station construction, the dam foundation rock mass classification is a very important basic geological work.Dam foundation of high arch dam with respect to other types of dam foundation stress and there are great differences, the dam foundation rock mass of dam abutment become the main load bearing part, the dam foundation rock mass deformation and anti sliding stability is higher than other types of dam foundation, so how to correct for rock mass quality classification and evaluation of arch dam foundation rock mass, thus providing reliable mechanical parameters of the rock mass, not only is the arch dam foundation selection of dam foundation. It is also the fundamental basis for the anti slide stability analysis of rock mass deformation in dam foundation and abutment. Therefore, it is of great significance to study the classification of rock mass of high arch dam foundation.In this paper, the Yalong River mengdigou hydropower station dam foundation rock as research object, based on a large amount of measured data as the basis, in a large number of field investigation and indoor test and statistical analysis based on the first-hand information, the research of mengdigou hydropower station dam site, the basic geological conditions of dam rock mass structural plane characteristics(including geological the characteristics of surface engineering structure at all levels of structural plane size grading, shape classification, alteration zone), and the physical and mechanical characteristics of rock mass characteristics, dam foundation, and on this basis, the influence of mengdigou hydropower station main factors of dam foundation rock mass quality, and selected the relevant evaluation indexes, the establishment of the foundation rock mass quality classification scheme, then carries on the division to the quality of the dam foundation rock. Comprehensive research, the main results of the following basic results:(1)Through the analysis of the basic characteristics of dam foundation rock, based on large amounts of investigations, structural surface acoustic wave test, field and laboratory tests, determine the evaluation factors of rock structures and main index, through the whole tunnel, Kv, RBI, fracture spacing Jv, acoustic wave measurement of the adit, in accordance with the "hydraulic generating code for engineering geological investigation"(GB 50287-2006) in the provisions of the division of rock mass structure and fracture spacing standard, selecting representative adit(each elevation one each), with 2m as an evaluation unit, rock mass structure division, to the rockmass structure classification of each unit, and for the same the evaluation results of Kv, RBI, Jv, sound value statistics, so as to get the Kv, RBI, line Jv, acoustic rock structure classification value. Thus, the structural division of dam foundation rock mass is obtained, and the structural division of rock mass is carried out, and the results can reflect the structural distribution of rock mass accurately..(2) Of granodiorite weathering of load, physical and mechanical characteristics of unloading, results show that: granodiorite rock is lithologically homogeneous, in addition to the development of faults, extrusion fracture zone outside, rock mass integrity better, rock mass quality classification is mainly affected by weathering, unloading and tectonic control. Saturated uniaxial compressive strength value, interval value under different weathering conditions, the numerical values have good gradient relationship, according to the actual application of many domestic projects, weathered zone and the relationship between rock mass quality, and the use of engineering analogy method to obtain different rock saturated uniaxial compressive degree and acoustic boundary value, and combined with the third chapter divides the rock mass structure, establishment of granodiorite granite rock mass quality classification scheme, operation scheme, completion of granodiorite granite rock mass quality classification.(3) To the altered rock type and output characteristic analysis, the altered rock zone according to the alteration, and the strength of alteration material differences, the single altered rock is divided into quartz filling belt, silicate alternation change belt, strong metasomatism and recrystallization zone(granite belt), weak metasomatic recrystallization zone(granite and clay belt), bake copy the softening zone(clay) has five bands. Again based on the altered rock zone in granite altered rocks, clay erosion variable proportion of rock and rock comprehensive wet compressive strength decrease rate, combined with corrosion altered rock zone of the characters, the erosion of the dam foundation rock belt is divided into S1, S2, S3, S4, four engineering character types. The altered rocks in accordance with single fracture type erosion rock, fault type altered rock, closely spaced fissure erosion type variable rock band output and physical and mechanical characteristics of rock mass quality classification scheme were developed, complete rock dense band of rock mass quality classification of erosion.(4) Combining the results of the quality of the granite flash rock and the altered rock mass, the rock mass quality classification of the whole dam foundation is completed..