泄洪洞掺气设施效果影响因素的主成分分析

为了揭示影响掺气设施效果的主要因素,收集了国内外31个大型水电工程泄洪洞中安全运行的73个掺气设施相关资料(包括掺气设施结构参数、设计条件下的水力参数和空腔长度等资料),统计分析了这些掺气设施各结构参数的选用频率分布和空腔长度的出现频率分布。在此基础上,应用主成分分析法,定量分析结构参数与水力参数对空腔长度的影响程度。统计结果表明,大多数掺气设施的挑坎高度tr选用范围分布在0~0.8 m区间,选用比例高达85.33%;挑坎角度θ选用范围多集中于4°~8°区间,选用比例达60.0%;坎前底坡i_1和坎后底坡i_2的选用频率多集中于0~0.15区间,选用比例约59%;空腔长度L出现频率绝大多数集中于6~36 m区间,出现频次超过98%;在空腔长度的诸多影响因素中,坎前坡度i_1和坎后坡度i_2对空腔长度的影响最大,均超过了28%,Fr的影响占据了25.12%,tr/ho的影响占据了15.01%,挑坎角度θ的影响最小,仅占2.62%。研究结果可为掺气设施的设计和运行管理提供参考依据。

Principal component analysis on factors of influence on effect of aeration facility for spillway tunnel

In order to reveal the main factors of the influences on aeration facilities，the relevant data （including the structural parameters of aeration facility，hydraulic parameters under design condition，cavity length，etc.） of 73 aeration facilities safely operated in the spillway tunnels of 31 large scale hydropower projects at home and abroad are collected herein，and then the selection frequency distribution of all the structural parameters of those aeration facilities and the occurrence frequency distribution of the cavity lengths are statistically analyzed as well. On the basis of this，the degrees of the influences from the structural parameters and the hydraulic parameters on the cavity length are quantitatively analyzed through the principal component analysis. The statistical result shows that the selection ranges of the aeration ramp height tr are distributed in a range of 0~0.8 m for most the aeration facilities with the selecting proportion as high as 85.33%，most of the selection ranges of the aeration ramp angle θ are concentrated in a range of 4°~8° with the selecting proportion up to 60.0%，most of the selection frequencies of both the bottom slopes before and after the aeration ramp i1 and i2are concentrated in a range of 0~0.15 with the selecting proportion of about 59% and the occurrence frequencies of cavity length L are mostly concentrated in a range of 6~36 m with the occurrence frequency over 98%. Among so many factors of the influences on the cavity length，the influences from both the bottom slopes i1 and i2 before and after the aeration ramp on the cavity length are the largest with both the influence rates are over 28%，the influence rate of Fr is 25.12%，the influence rate of tr/ho is 15.01%，while the influence rate of the aeration ramp angle θ is the least with the influence rate of only 2.62%. The analysis result can provide a referential basis for the design and the operation management of aeration facility.