| The proposed Songta Nujiang hydropower station,located in Chayu County,designed with double curvature concrete arch dam height of 318 m,the world's most similar type of dam.Songta Hydropower Station narrow valley,steep valley slope,outcropping lithology Yanshan granite,rock intact,except for the steep angle dikes,faults,pressing surface,the surface is not a gentle inclination weak structural development.But the dam shallow slope portion has a gentle inclination in the development of a fissure.The crack has implications for control abutment and stability of rock slope.Study has important implications for the stability ofrock steady mode.And carry out in a gentle inclination connectivity rate.During the study of the dam area on both sides of a total of 65 footrills carried out a detailed survey,a total of 17,149 measured fissuring,wherein the slow crack 7602.In this paper,based on detailed survey data,statistical analysis,to identify the basic characteristics of the two sides in the lower elevation of the low angle crack,and using the full trace length method,based on the study of non-deterministic model and fracture network in two Monte-Carlo simulation cranny with little obliquity connectivity rate.This paper made mainly awareness:(1)The dam fissuring with little obliquity basic development characteristics: low angle crack in the dam site area pinecone higher degree of development,the number of accounts for half of the total number of fractures.Overall,it was "a slow two steep" developmental characteristics,namely a set of two steep bifida and cleft relatively slow development.Wherein the low angle crack inclination mostly concentrated between 20 ° ~ 60 °,was "down character" distributed on both sides of the mountain.On strike,NNW-SN group and the NNE group is most developed.Spatially,it was significantly uneven,that is "sparse" ~ "secret" ~ "sparse" ~ "dense" phase.On the right bank of the slow crack density was significantly larger than the left bank;low elevation on low angle crack density was significantly greater than the high elevation on low angle crack density.(2)crack with little obliquity connectivity rate characteristics:a.Full trace length method: by total trace length method 1670,1720,1770 carried down the river to a total of five adit research and analysis,the results showed that: the higher the altitude,the lower the rate of connectivity(underwater adit exception);connectivity with the right bank rate on the left bank;within the scope of the right bank of 1720 m elevation block connectivity with the maximum rate of 62.44%,within the range of crack 1770 m elevation block connectivity was 55.09%,within the range of crack 1670 m elevation block connectivity was 47.13%.Within the scope of the block on the left bank 1720 m elevation fissures connectivity was 50.6%,within the range of crack 1670 m elevation block connectivity was 26.25%b.Based on non-deterministic model Methods:This method is mainly considered in the low angle crack uneven distribution,then be divided into different densities for each tunnel segment in accordance with adit,then calculated separately by Method L and H Law various sliced elevation at different depths advantage tendencies connectivity rate low angle crack results.Then for a particular part of the rock(such as arch-side),we decided to deal with them in strikes and dips.The results showed that boils down to: the left bank of communicating values mostly in the 20% to 40%,mostly in the right bank of communicating values between 30 to 50%.Connectivity rate seems to increase with increasing elevation.The results showed a tendency attributed to: the left bank of the anti slider body 11 is divided on slow crack zone(zone),which can constitute a potential bottom sliding surface area with the maximum connection rate for the left bank LB-4 for k = 54.7%,on the right bank RB-4 for k = 51.4%.c.Fracture Network Two Valmont Carlo simulation method: through each adit in slow crack basic geometric features statistical analysis also took into account the slow crack uneven distribution of each adit tunnel segments were divided,then use RDNS-2D simulation software segment,the results obtained for each level connectivity rate cut at different depths elevation advantage tendencies slow crack.Also it is attributed strike and dip.The results showed that boils down to: dam connectivity rate with elevation changes obviously,the higher the elevation,the lower the value of the communication rate,the value of the communication rate increase with deep cave becomes smaller.Right bank of the lower elevation rate communication concentrated between 40% to 60%,high elevation rate communication concentrated between 20% to 30%;the left bank of low elevation centralized communication rate between 20% to 40%,high rates concentrated in elevation communication between 10% and 30%.The results showed a tendency attributed to: the left bank of the anti slider body 11 is divided slow crack zone(zone),which can form a bottom sliding surface area with a potential maximum value of k in the left bank of LB-5 = 30.8%,on the right bank of k RB3 = 52.0%.Combined with the results of a three-dimensional network simulation of Jilin University,a comparative analysis of several methods can be found: a three-dimensional simulation of network connectivity rate,is a large value(high value)level;the second connectivity network simulation rate,at high elevations belong to low level,low-elevation belong to the middle level;trace length estimation,at high elevations belong to the middle level,at low elevation belong to low levels.Finally,the advantages and disadvantages of these three methods were analyzed after using trace length estimation method results in The low-angle fracture zone results,the recommended values Songta Dam Area connectivity rate: LB-1: 57.3%,LB-2: 38.0%,LB-3: 36.7%,LB-4: 54.7%,LB-5: 35.1%,LB-6: 25.9%,LB-7: 29.4%,LB-8: 33.8%,LB-9: 32.4%,LB-10: 38.5%,LB-11: 14.4%;RB-1: 51.4%,RB-2: 63.1%,RB-3: 42.7%,RB-4: 51.4%,RB-5 : 50.5%,RB-6: 46.5%,RB-7: 52.2%,RB-8: 17.9%,RB-9: 28.7%,RB-10: 24.9%. |
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