Study On Rock Quality Classification System And Its Application Of Toppling Deformation Rock In Western Hydropower Projects

With the frequency and expansion scope of human engineering activities, the toppling deformation and failure has largely occurred in rock slope of water conservancy and hydroelectric, mining, railway, highway and etc at home and abroad, such as Canada Frank landslide, the American Brilliant excavation slope, the domestic slope dumping of natural arch secondary hydroelectric station in south room, open-pit mine slope in Jinchuan and etc.Toppling deformation is a typical deformation failure mode of layered rock slope rock slope in valley area. This developed largely in toppling rock slope, especially the rock steep slope cutting the valleys deeply. Along with the flourish of western hydroelectric projects, various huge toppling deformation rock emerge in complex geological environment, such as the left bank of Three beach dam and hydrometric Station dam in Jinping hydroelectric Station Ya-lung River, the Mabu bank of Xiangjia dam in Jinsha River, the Gehe rock workshop of Qingjiang River and etc.The huge toppling deformation rock hanging on the nodal region and reservoir area becomes a geological threat to water-power engineering. Upon the background, it is particularly important to analyses the development rule of western deformation rock, built the rock quality classification system of it, be aware of and solve the problem of slope toppling deformation and failure in water-power engineering recently.With the method of engineering geology and rock mechanics, combining the technique of geological survey, theoretical analysis and ArcGIS, the paper takes a research on the following four aspects aiming at the western hydroelectric toppling deformation rock:(1) The paper makes statistics of toppling deformation and failure of rock slope examples in western hydroelectric, mining, highway engineering, analyzes the geographical distribution rule of water and electricity, mining, highway engineering example referring to China’s administrative map, emphatically western hydroelectric engineering distributed in the west.Based on ArcGIS and the Analytic Hieraechy Procces(AHP),toppling deformation distribution susceptibility is evaluated in the west of China considering regional geological conditions(geomorphology, stratigraphic age,seismic intensity, tectonic stress).Based on ArcGIS and the information computation method, the paper chooses 11 main river developed in the west such as the Jinsha River, Ya-lung River and Lantsang to evaluate toppling deformation distribution susceptibility. This method studies the development rule of toppling deformation rock existed in different drainage basin, especially in the upstream, midstream and downstream of typical river. Combining with the results of information computation partition, the paper analyzes the relationship between the developing factors, that is lithology, slope height, slope Angle, growth height, horizontal and vertical development depth, and the information content, obtains the correspondence between distribution characteristics of toppling deformation rock and developing factors in different levels of information partition.(2) Through the study of dumping degree of toppling deformation rock and based on the cantilever beam model, the paper analyses the mechanical characteristics of bending deformation zone, puts forward the quantitative index to divide the bending deformation zone, so as to provide the basis for site decision and stability evaluation of the toppling deformation rock. After the analysis of the rock quality classification system applicability of common slope, CSMR evaluation system can apply for the hydroelectric engineering slope, especially the slope with plane failure and wedge failure, but for the toppling deformation rock quality classification system. The paper summarizes geometrical characteristic development rules of western hydroelectric toppling deformation rock, modifies the discontinuity occurrence modifier F3, and puts forward rock grade evaluation system QD-CSMR for the western hydroelectric toppling deformation rock based on the analytic hierarchy process and the CSMR rock quality classification system. QD-CSMR= ξRMR-λF1F2F3+F4 (the value restrictions and range of RMR、λ、F1、F2、F4 is consistent with CSMR system).(3) Take the taking-value method of mechanical parameters of hydropower engineering slope rock mass for reference, the paper makes sure the engineering geological condition of toppling deformation rock, the taking-value method of mechanical parameters of the rock mass, the corresponding relationship between engineering stage and the evaluation methods to refine the mechanical parameters of rock mass value. The ideas of how to determine the rock mechanical parameters of western hydroelectric toppling deformation landslide are as follows:basicly, it uses the indoor and outdoor test to determine the mechanical parameters scope preliminary. Then, it takes the estimate method such as QD - CSMR, HB criterion as the core to determine the scope accurately. Finally, it supplements the empirical method to check the scope.(4) The paper takes the example of diversion channel slope in a western hydroelectric station to studies the toppling deformation phenomenon. Through the investigation of the slope engineering geological conditions, the paper analyzes the deformation and failure characteristics and the displacement of the slope evolution, inverts the whole process of the slope deformation and failure using the monitoring data and kriging interpolation method. The paper analyses the slope deformation and failure characteristics and reveals the deformation and failure rule of slope evolution at three different working conditions through the generalized geological model of slope and UDEC software. Based on the above research, combining with the kriging interpolation method and UDEC results, the paper makes contrastive analysis of the diversion channel slope displacement variation characteristics, studies the temporal and spatial evolution law and the deformation mechanism. The result shows that the evaluation results of kriging interpolation method and UDEC reach good consistency with the actual condition.The innovation of this article is:(1) Based on statistical analysis for toppling deformations in western China, choosing 4 elements of regional geology including topography and geomorphology, stratigraphic age, seismic intensity and tectonic stress, susceptibility of toppling deformations in the west of China is evaluated. The study zone is divided into very high easy-happening area, high easy-happening area, medium easy-happening area, low easy-happening area and very low easy-happening area. Very high easy-happening area is mainly distributed in mountains of southwest China and small amount area of the northwest and Tibet.(2) Modified QD-CSMR system of rock mass quality classification is proposed based on CSMR system aiming at western hydropower projects in China. QD - CSMR= ξRMR-λF1F2F3+F4 (the value restrictions and range of RMR、λ、F1、F2、 F4 is consistent with CSMR system).(3) Aiming at toppling deformation rock from an angle of rock behavior itself, engineering countermeasures are proposed as follows:①Changing shape of slope body, adjusting stress distribution;②Replacing part of the slope body considering the scale of rock of grade Ⅲ and Ⅳ;③Anchoring unstable key blocks, improving stability of slope body;④Modifying the properties of solid area, improving physical and mechanical parameters⑤Setting cutting off water and drainage engineering considering the scale of the toppling deformation.