What type of loader was used when the Three Gorges Hydropower Station started construction?

Three Gorges Power Station Project Construction

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1. Project Overview

The Three Gorges Power Station is the main power source for the Three Gorges Water Conservancy Project during its operation period. The factory site is located in the mountain between the ship lift sand sluice and the left bank power station. It is an underground factory type and is equipped with two Francis turbine generator units with a single capacity of 50,000 kW. The water inlet of the water diversion system is located on the dike of the approach channel upstream of the ship lift, and the outlet of the tailrace system is located in the tailrace channel of the left bank power station. The main engineering projects include: civil engineering of water diversion systems, underground workshops, tailwater systems and other buildings, installation and commissioning of some metal structure equipment and embedded parts, cofferdams, etc. The Three Gorges Project Command of the Armed Police Hydropower Corps is responsible for the construction.

The main construction project in 2004 was underground cavern excavation and support. The filling construction of the cofferdam began on December 29, 2003, and the cofferdam construction was completed on April 18, 2004, with water-retaining conditions. On April 21, the excavation of the 1# and 2# construction support tunnels with a total length of 363m began.

The ventilation tunnel excavation was completed on February 17. On May 16, the transportation tunnel excavation and system support were completed and connected to the underground factory installation room. By the end of the year, the leveling concrete pouring of the floor of the ventilation tunnel and the traffic tunnel entering the factory was completed, and the construction of the lining wall began.

The underground factory is a key control project that occupies the straight-line construction period of this project. Excavation of the first floor of the main factory began on February 18, 2004, and the first floor of the roof arch of the main factory was opened on April 13. The excavation was completed, and the system support of the first floor of the roof arch was completed on May 23. After the main factory building and the access tunnel were connected, the excavation of the rock anchor beam layer of the main factory building began. On July 2, all the rock anchor beams of the main factory bridge machine were excavated and formed. On August 24, the rock anchor beam to the main factory building elevation was completed at 63.5 m excavation and rock anchor beam system bolt support. Concrete pouring of the rock anchor beam began on August 26. On October 18, excavations were carried out from the main powerhouse, diversion tunnel, tailrace tunnel and other working surfaces to the main powerhouse elevation below 63.5m. At the end of November, the excavation and support of the layers below the turbine layer (55.0m) were completed, and the main powerhouse was fully shifted to concrete and metal knot construction.

The 1# and 2# diversion tunnels were connected to the main plant on September 5. By the end of 2004, all the upper and lower sections of the diversion tunnel were completed. The 1# and 2# tailrace tunnels were expanded except for the tailrace gate well. Everything outside is completed. Concrete construction began one after another at the end of 2004.

II. Main construction features of the project

The power station project is a comprehensive underground engineering project. Its construction project involves general open-air stone controlled blasting excavation and underground cavern excavation. , underground factory excavation, anchor support processing such as anchor rods and sprayed steel fiber concrete, foundation grouting processing, concrete construction, installation of metal knots and electromechanical equipment, etc. The professional technical field is wide, the structure is complex, the technical requirements are high, and the construction schedule is tight. The construction is carried out under the conditions of the existing buildings and power generation operation in the second phase. The excavation and blasting control requirements are high, the site is small, and the construction is difficult. The excavation and construction of the underground engineering of the power station mainly has the following technical characteristics:

The excavation and forming of the underground powerhouse is the key technology for the construction of this project, especially the excavation and forming technology of the rock anchor crane beam rock platform of the power plant. , as well as the excavation and forming technology for the 47.1m-high vertical wall of the factory building.

The underground cavern group has a complex structure, compact design and layout, large construction interference with each other, and it is difficult for conventional large-scale tunnel excavation equipment to be efficient and economical. It is necessary to develop self-made excavation equipment and study reasonable construction plans based on local conditions.

The construction technology of vibrating hole high-blasting anti-seepage wall is set up in the cofferdam. In addition to being used on the third phase cofferdam in the Three Gorges Project, this is the second time it has been adopted. The characteristic of this technology is the integration of drilling and spraying. change.

3. Main construction guarantee measures

(1) Technical measures for underground factory excavation and forming

The key to underground factory excavation is to control the roof arch and side walls of the factory The excavation is formed, and the quality of the blasting operation is controlled to ensure the stability of the surrounding rock, especially the excavation quality of the rock anchor beam platform. Secondly, issues such as which blasting method to adopt, how to ensure the forming quality, whether the surrounding rock is stable after blasting, the relationship between the rock anchor beam rock platform and the factory building trough, and the excavation of the lateral protective layer, especially the rock platform construction The issue of optimal timing and shortening the excavation period of the rock anchor beam platform needs to be demonstrated and analyzed to formulate corresponding construction quality assurance measures.

Based on the excavation experience of the Three Gorges Ship Lock and Tongbai projects, before the formal excavation of the vertical walls and rock anchor beams of the underground power station’s underground power plant, selections were made on the upstream and downstream side walls where the rock anchor beams of the main power plant are located. Conduct blasting tests at appropriate locations to obtain reasonable blasting parameters.

(2) Technical measures for underground cavern groups and shaft excavation construction

1. Optimization and improvement of excavation equipment

Each cavern group of the Three Gorges Power Station Project They are mainly in the shape of city gates or horseshoes. The amount of excavation work for each cave is generally not large, but the cross-section is small, the caves have many bends, and the construction period is tight. After comparison and selection, a lightweight and flexible air-leg type hand drill was used and placed on a self-made adjustable and extendable trolley that is easy to move and carry out full-section excavation of the cavern.

The self-made trolley has a steel pipe and steel frame structure, using a 5t to 8t truck chassis as the load-bearing platform and walking part, and the original carriage part is welded to the operating platform. The operating platform is generally designed to have three layers. Each of the lower two layers is 2.0m high. It is mainly used for hole making and charging construction of cavern side walls and cut holes. The third layer is made into an adjustable platform to adapt to the changing cross-section of the cavern. Finally, there are construction requirements for raising or lowering the cavern height. At the same time, the wind, water, and electricity interfaces are fixed on the trolley to simplify construction preparation time and facilitate operation. Judging from the use results, the five self-processed trolleys can meet the needs of engineering construction, and the monthly peak excavation footage reaches more than 360m.