Key technical problems in the design of Tingzikou project

1, deep anti-sliding stability of the dam

The rock mass of dam foundation is composed of interbedded soft rock and medium hard rock, and there is a weak interlayer downstream of the moderate dip angle of rock mass. The weak interlayer or soft rock distributed in the dam foundation rock mass can form a sliding surface that is not conducive to the dam's anti-sliding stability. According to the current code, in-depth anti-sliding stability analysis is needed.

Judging from the events of dam construction on red bed dam foundation rock mass at home and abroad, the primary problem is the existence of weak interlayer in dam foundation. Weak interlayer with low shear strength generally exists in the dam foundation of Tingzikou Water Control Project, which constitutes the main controlling factor of dam foundation stability. Due to the uncertainty of mechanical parameters of weak interlayer, the difference of rock mass structural conditions and lithology, the deep sliding mode of dam foundation is complex, which brings a series of key technical problems to the stability evaluation of gravity dam foundation and the determination of engineering treatment measures. There are 50 dam sections in this project. According to the distribution elevation of interlayer in each dam section and whether there is corresponding anti-sliding rock mass downstream of the dam body, the double inclined sliding surface method and single sliding surface method are used for calculation respectively.

The treatment measures of deep anti-sliding stable foundation generally include: setting concrete groove at dam heel and cutting off interlayer plane; Adding impervious plate in front of the dam to reduce uplift pressure; Set drainage holes in dam foundation to reduce seepage pressure; Reinforce the toe of the dam and increase the resistance of the resistance body. After comprehensive comparison, the scheme of setting concrete trough below dam heel has the advantages of less investment, convenient construction, safety and reliability, and is recommended. In order to ensure the concrete tenon to play its role, the concrete tenon should be 2.5m below the interlayer.

2, high head bottom hole shape

The main task of the bottom hole is to discharge flood and sediment, and it is also used as the diversion bottom hole during the construction period. There are five bottom holes in Tingzikou Water Control Project, and the bottom holes adopt the type of underflow energy dissipation. The working head of the bottom hole arc working gate is 87.8 meters under the design condition and 89.54 meters under the check condition. The design flow rate of the bottom hole is 9800 m3/s, and the flow rate into the stilling basin is 45 m/s. The design of the bottom hole of the pavilion is characterized by large flow rate, many holes and large orifice size. In addition, cavitation erosion and erosion are another key technical problem in the engineering design of Tingzikou under the operating conditions of high head and high sediment concentration.

3. Engineering quality

A series of engineering records have been created: according to the requirements of "building a high-quality demonstration hydropower project" in Datang, top-level engineering planning and strict management have been implemented, and the largest sand and gravel processing system in Asia has been built; Built the translation tower-less cable crane with the third span in China, and won the first prize of national cable crane installation scientific and technological progress; It has set a new world record for the daily pouring of concrete for the 10,000-meter warehouse receipt, with construction on February 30th 10 year, and RCC15,840 cubic meters. It has created a new world record for the construction strength of single silo concrete in the dam main project of the same industry, with the highest warehousing strength reaching 924 cubic meters per hour. 1October 22nd, 20 1 1, 18.8m three-level natural aggregate RCC long core wall was taken out, which set a new world record for three-level natural aggregate RCC long core wall. From 20 1 1 year1February 15 to 201February/February/5, the total installation period of No.2 turbine volute was only 62 days, which was more than one month ahead of schedule, setting a new record for a single hydro-generator set of the same scale and type in China. On March 3rd, 2065438, the RCC core sample of19.59m was successfully taken out of Dam No.43, which once again set a new record for the long core of natural aggregate RCC.

4. Flood control effect

On July 23 and 25, 20 10, Jialing river basin was hit by a catastrophic flood once in nearly 20 years. The second-stage cofferdam of Tingzikou Project effectively reduced the flood peak by 4,000 cubic meters per second, and retained nearly 400 million cubic meters of flood water, thus avoiding the emergency relocation and flood loss of 654.38+10,000 people in Cangxi, Langzhong, Nanchong and other cities in the lower reaches of the Yangtze River.

On July 22nd, 20 13, Tingzikou Water Control Project ushered in the largest flood peak since the flood season, and the inflow reached 1 1000 m? /s, the flood is a threat to the downstream. Tingzikou Water Control Project has reduced the flood peak without flood regulation function, and successfully completed the task of shifting the peak, which embodies the responsibility and mission of Tingzikou based on the happiness and well-being of the people in the old area of northern Sichuan, taking care of the overall situation, loving their jobs and being brave to take responsibility.