Construction conditions of Longxikou junction project of Minjiang Navigation and Electricity

Longxikou cascade is located in Qianwei County, Leshan City, the mainstream of Minjiang River. The Qianwei-Yibin Highway passes through the left bank of the dam area, and the Leshan-Yibin shipping waterway is the exit channel for Sichuan transportation, with convenient transportation.

There are sand pebbles and impervious soil materials needed for dam construction in the upstream and downstream of the dam site area, and the reserves meet the requirements.

The river valleys on both sides of the dam area are low mountains and hills, terraces are widely distributed, and the construction site layout conditions are good.

There are navigation requirements during the construction period of the river section where the project is located.

Steel, cement, mechanical and electrical equipment and other foreign materials and equipment are brought in from Chengdu and Leshan.

(2) Construction diversion and schedule arrangement

The construction diversion of this project adopts phased diversion method, which is carried out in four phases.

In the first stage (June of the first year 10 to May of the second year), the open channel on the left bank was constructed, and the diversion standard was selected 10 flood return period, and the diversion design flow was 7950m3/s.

In the second stage (from June of the second year to September of the fourth year), the right bank 15 spillway gate and ship lock will be enclosed. 20-year flood is selected as the diversion standard, and the diversion design flow is 36,200m3/s.

The third stage (June of the fourth year 10 to May of the fifth year) revolves around the 8-hole spillway gate on the left bank and the left bank powerhouse. The flood return period of 10 is selected as the diversion standard, and the diversion design flow is 7950m3/s.

In the fourth stage (from June of the fifth year to May of the seventh year), concrete pouring, metal structure installation and unit installation are carried out around the left bank powerhouse. The flood control standard of powerhouse gate is once every 20 years, and the corresponding design flow is 36,200m3/s. ..

The total duration of the project is 84 months, of which the project preparation period is 12 months, from July of the first year to June of the second year; The construction period of the main project is 69 months, from June of the first year 10 to the end of September of the seventh year, two units have power generation conditions at the same time; The project completion period is 12 months, starting from the seventh year 10 to the end of September of the eighth year.

(3) Navigation during the construction period

In the first stage (from June 5438+00 of the first year to May of the second year), the open channel on the left bank was built, and the narrow riverbed on the right bank was used for navigation.

In the second stage (from June of the second year to September of the fourth year), the left bank diversion open channel was used for navigation, and the designed bottom width of the open channel was 250m m.

The third phase (from June of the fourth year 10 to May of the fifth year) is navigable with a permanent lock.

The fourth phase (completed in June of the fifth year) is navigable by permanent lock.