长江葛洲坝水利枢纽卵石推移质的特性与输沙量

THE CHARACTERICS AND DISCHARGE OF THE PEBBLE BED LOAD AT GEZHOUBA PROJECT OF THE UPPER CHANGJIANG RIVER

葛洲卵石推移质的级配较宽,多数卵石的硬度较大,不同粒径组卵石的平均磨圆度为2级至4级。根据区域地质与地貌特性在卵石推移质岩类组成上的反映,将葛洲坝卵石推移质来源分为三个补给区,用由最小二乘法建立的法方程,根据各补给区与汇入区卵石推移质岩类鉴定资料,计算出各补给区卵石推移质汇入百分数x_1、x_2、x_3。黄柏河补给区汇入百分数x_3与其卵石推移质输沙量均为已知,据此计算出葛洲坝水利枢纽卵石推移质输沙量为7.08086×10~5t/a。该输沙量同1973-1987年宜昌水文站测验的卵石推移质输量为6.994×10~5t/a十分接近。采用乐天溪补给区实测资料的验证,实测值与计算值两者只相差1.2％。

This paper summarizes the results of investigatiions on the pebble bed load (the PBL) with d>10mm at the Gezhouba Project and makes a proposal for analysing the characteristics of the PBL by using the geological and geomorphological method, and for calculating the quantity of the PBL by the petrographic classification analysis method. The hardness of the PBL is dependant upon petrographic composition, At the Gezhouba Project about>50％ of the PBL have the hardness more than 3. The degree of mean psephioity (P_m) of the PBL in different grain sizes is between degree 2 to 4. In the light of regional geological and geomorphological characteristics and their effects on petrographic composition, the source of the PBL at the Gezhouba Project of the upper Changjiang River can be divided into 3 supplying regions. The converging region is the Gezhouba Project. Based on the evaluation of petrographies on the supplying regions and converging region (Tab.1), and by using the least squares mathod, a normal equa- tion is formuated.Then all the converging percentages of the supplying regions are calculated. The research has shown that 87.8％ of the PBL come from the supplying region of the Upper Changjiang River Upstream of Sandouping. With the known converging percentage of the supplying region of Huangbaine River (x_3) and its amount of the PBL, the total amount of the PBL at the Gezhouba Project is computed to be 7.08086×10~5t/a .This value agrees quite well with the measured average amount of 6.988×10~5 tons per year at the Yichang gauging station from 1973-1987. This method is also verified by the measured data from the supplying region of Letianxi Creek (x_2), which shows that there is only a difference of 1.2％ between the calculated value and the measured value.