| Zhifanggou is located in the south of Pingliang city in Gansu province,it is a branch of Ching River on the right bank,which from the Hulang mountain.It has a area of 21.87km2,a length of 18.7km and an average slope of 2.6%.It has 2,655 residents and six enterprises and institutions in the Watershed.It has occurred of mountain flood disasters in the history,caused serious harmness.For it throughs the eastern Pingliang city into Ching River,Zhifanggou has the direct threat of mountain torrents to 200,000 people's life and property security in the eastern district of pingliang,therefore,Implementation the mountain torrent ditch control Engineering for Pingliang Zhifanggou Watershed,is benefiting for control the mountain torrent ditch,improve the basic conditions,win over the enough time for the coast residents to escape when meet mountain torrents flood,ensure the security of the residents on the coast and in the eastern Pingliang and property safety,play a positive role in the development of local economy.This dissertation takes the Pingliang Zhifanggou mountain torrent ditch as control object,design the control engineering measures.The main contents of the paper are as follows:First,this dissertation combines the strategies and excellent practices of flood control worldwide with the actual situation of flood control project.It figures out that small watershed flood control management should focused on the point management and prevention.As a result,the flood control management forms a comprehensive protection system which gives priority to shore protection engineering,channel dredging and river engineering building.Second,The flood calculation is calculated by using the regional empirical formula method and reasoning formula method,then verify each other,the design flood is final determined according to the measured flood peak.According to the analysis,the empirical formula is only related to the basin location and the basin area,but it is not related to the channel ratio and the underlying surface factors,and has certain limitations.Reasoning formula method to calculate the total peak flow is relatively close to the rail value,compare the two methods of calculation results,fifty years and a decade is within 5% of the peak flow,once every five years the difference of the peak flow at around 15%.Then according to theZhifanggou reservoir dam site measured on 24 July 1957,the largest flood peak of 158 m3/s,1957,55 years ago,the measured flood peak flood peak per basic equivalent to fifty years,therefore the calculation is reliable.For the sake of safety,this design uses the method of inference formula to calculate the flood results.Third,the dike structure is one of the main factors influence the project cost,compare the structure and cost of the gravity type,slope type and acclivitous coal seam type,and then choose the most reasonable and economic structure for each engineering section.Forth,on both sides of the main channel have high mountains and steep slopes,and many small branches.the runoff from a rainstorm flow along the road on both sides of the village,badly damaged the residential areas,road embankment,earth canal,ditch buildings,farmland and orchard,to avoid mountain flood causes big economic loss for local people,specially designed flood-cutting channel project on the single side of the village road which concentrates much surface runoff to eliminate the road surface runoff.The end of the flood-cutting channel introduces the road runoff into the watercourse through the passing culvert.Final,In order to prevent the resident on the platform of the right bank of the Xiaomiaogou which is a branch of Zhifanggou from being washed down by the storm,in this section,a drainage channel has been designed,and also a trapeziform earth-retaining wall was set up on the right bank to ensure the safety of people's life and property.More than 200,000 people are benefiting from this engineering,It has good economic,social and ecological benefits. |
PDF Full Text Request