| The deep river valley in the dam site of the lancang river is obvious,the unloading is strong,the seismic activity is frequent,the fracture rock mass of the right bank slope is more,and the ductile shear zone of the high slope position causes the lithologic changes of some of the Dacite.At the same time,the complex engineering geological conditions can lead to some differences in the quality of rock mass.Therefore,exampled by a certain power station dam site area rock mass quality classification of the lancang river as the research object,in view of the scene of the landform survey peace adit data collection and statistical analysis,and using the idea of combining qualitative and quantitative determine the dam site area of slope rock mass weathering unloading boundaries,and then on the basis of weathering unloading line preliminary classification of rock mass quality of dam site area,finds out the cause of the differences,and correction of rock mass quality classification method,finally it is concluded that appropriate for the hydropower station dam site zone of slope rock mass quality classification result.The main research results are as follows:(1)Based on the field investigation of dam slope peace adit of actual measurement and description,on the basis of the rock mass structure surface classification standard,this paper sets out the various adit fracture distribution and development characteristics,analyzes the dam site area Ⅲ,Ⅳ,Ⅴ level engineering geological characteristics of the structure,and carries out the structural plane engineering geological characteristics of the mathematical statistical analysis.(2)According to the analysis of the spatial combination characteristics of the structural plane,it is found that the advantages and weak structural surface of the left bank are basically steep slope,and the left bank slope is relatively stable.The advantages and weak structure of the right bank are mainly divided into a group of steep slopes and a set of gentle slope,which is easy to form unstable sliding surface,and the right bank is more unstable.Therefore,on the left bank of the dam site,the rock mass on the right bank of the dam site is relatively poor.(3)According to the results of the seismic wave speed ratio and the number of fractures in the 5m tunnels,and combined with the boundary result of the field qualitative demarcation,the result of the final rock weathering boundary of the dam site was obtained.At the same time,according to crack open width in the adit and seismic p-wave velocity of two quantitative indicators,also in combination with the results of field survey and qualitative,the dam site area is obtained finally determine the strength of the unloading line.(4)According to the statistical analysis,the preliminary classification results of rock mass in the dam site are obtained by statistical analysis of the rock saturation compression strength,the spacing of the fracture surface,the integrity coefficient of rock mass and the RQD adit.(5)The BQ classification and RMR grading classification method respectively modifies.It is mainly reflected in the revised classification of the BQ classification,supplemented by the correction coefficient K1 of the groundwater correction coefficient,the correction coefficient K2 of the main weak structural surface,and the correction factor K3 of the effect of the ground stress.The difference of RMR is mainly embodied in three weights of R1,R2 and R3,and then the three weights are corrected.The calculated results of rock mass quality classification are in agreement with the revised BQ results.It provides further theoretical research for the study of rock mass quality.It is concluded the mechanics parameters value of the different level of rock mass and the rock mass structure.(6)Based on PDJ04 tunnel rock mass quality analysis,founding part of rock mass of the right bank slope,is affected by the ductile shear zone,from general dacite to ductile shear zone in the mylonitization dacite.This part of rock has low saturation compressive strength,which leads to low quality grading of rock mass. |
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