长距离输水工程输水能力复核问题探究

Calculation of the Actual Discharge for Water-SupplyProjection in Long-Distance Pipelines

长距离输水工程是实行调水、补水以解决水资源短缺或改善枯水期水环境的调(引)水工程之重要组成部分。常常由于设计时未能充分考虑地形地貌和土地开发利用实际情况,导致实际输水流量与设计输水流量存在较大差异,则需要对其实际输水能力进行复核。该文提出复核长距离输水工程输水能力、计算实际输水流量的方法,并以广州市三涌补水工程的输水系统——东圃泵站和环城干线管道为例,分别复核泵站初设、管道初设、管道施工3种工况的输水能力。复核计算结果表明,泵站初设、管道初设、管道施工3种工况的输水流量分别为6.02 m^3/s、5.15 m^3/s、4.30 m^3/s,与原设计的输水流量5.775 m^3/s相差愈来愈大。若再考虑阀井、阀件(排气阀、蝶阀、排泥阀)及空气阻力的作用,东圃泵站的输水流量进一步降低,这与在长虹调蓄湖实测的输水流量3.85 m^3/s基本吻合。由此可见,设计时不宜简单按相关规范将输水管道局部水头损失按沿程水头损失的5%~10%计,宜将泵站设计及输水管道设计同时进行,结合实地调查尽可能充分考虑地形地貌和土地开发利用实际情况,从而合理选择泵机机型及组数。

The long-distance water delivery project is an important part of the water diversion project that implements water diversion and water replenishment to solve the shortage of water resources or improve the water environment during dry seasons.Due to the failure to fully consider the topography and landforms and the actual situation of land development and utilization,resulting in a large difference between the actual water supply flow and the designed water supply flow,it is necessary to recheck its actual water delivery capacity.This paper proposes a method for rechecking the water delivery capacity of long-distance water delivery projects and calculating the actual water supply flow.Taking water delivery system of Guangzhou Sanchong Water Supply Project—Dongpu Pumping Station and the main city pipeline as an example.Recheck the water supply flow of the three working conditions of the initial installation of the pump station,the initial installation of the pipeline and the pipeline construction.The results of the recheck calculations show that the water discharge in the initial installation of the pump station,the initial installation of the pipeline and the pipeline construction are 6.02m^3/s,5.15m^3/s,and 4.30m^3/s,which is quite different from the original designed water discharge of 5.775m^3/s.If the effects of valves and air resistance are considered again,the water discharge of Dongpu Pumping Station will be further reduced,which is similar to actual water discharge measured in Changhonghu Lake of 3.85m^3/s.It can be seen that the design should not simply calculate the local head loss of the water pipeline as 5%~10%of the head loss along the way according to the relevant specifications.The pump station design and the water pipeline design should be carried out at the same time,and the field investigation should be considered as fully as possible.Terrain and landform and the actual situation of land development and utilization,so as to reasonably choose the type and number of pumps.It can be seen that the design should not simply calculate the local head loss of the water pipeline as 5%~10%of the head loss along the way according to the relevant specifications.The pump station design and the water pipeline design should be carried out at the same time,and the field investigation should be considered as fully as possible.Terrain and landform and the actual situation of land development and utilization,so as to reasonably choose the type and number of pump stations.