China Guodian Changyuan Jingzhou Cogeneration Phase II Expansion Project proposes to build 2×350MW coal-fired cogeneration units, which is a "13th Five-Year Plan" coal power construction planning project in Hubei Province. The project is located in Shacheng District, Jingzhou City, Hubei Province. The construction of this project is scheduled to start on October 28, 2021, and the first unit will be put into operation on February 28, 2023, and the second unit will be put into operation on April 28, 2023. Our company undertook the trial piling works of bored piles and PHC pipe piles for this project, which started on June 09, 2021, and the trial piling works were all completed on July 06, 2021,
Trial pile construction of bored piles: 11 concrete piles with diameter of 800 mm and length of 31.5 m in test area No.1, using C35 concrete for pile foundation, using slurry-support construction technology, including test piles of 3 bored piles and 8 anchor piles, entering the bearing layer of pebble layer of ⑦≥2.0m.
Trial pile construction of PHC pipe pile: (1) there were 22 prestressed PHC pipe pile in No. 2 test area, including 19 pipe piles with a diameter of 600 mm (3 trial piles and 16 anchor piles), 3 pipe piles with a diameter of 400 mm, entering into the ⑦ bearing layer of pebbles 1.5m. Anchor piles were poured with micro expansion fine stone early strength C35 concrete, and pipe piles were constructed by hydraulic hammer piling machine. (2) There were 3 PHC prestressed pipe piles in No. 3 test area, all of which were trial piles, and constructed by hydraulic hammer piling machine.
In the whole pile test project, 3 cast-in-place piles were tested by vertical compressive static load test, 4 by vertical uplift test, 3 by high strain test and 11 by low strain test. The test results showed that the vertical compressive bearing capacity and vertical uplift test of single pile met the design requirements; The low strain test showed that there were 11 class I piles, accounting for 100%; A total of 6 pipe piles with pile diameter of 400 mm and 600 mm were tested by vertical compressive static load test, 2 by horizontal static load test, 6 by high strain test and 22 by low strain test. The test results showed that the vertical compressive bearing capacity and horizontal static load test of single pile met the design requirements; The low strain test showed that there were 22 class I piles, accounting for 100%.
All the staff of the project department worked together, communicated with the owner and the general contracting design institute for many times, determined the depth of the bottom bearing layer by advance drilling for the characteristics of this project, tested driving for many times, communicated with the supplier during the period and determined the purchase of pipe piles in small quantities in batches to ensure the timely supply of project materials, thus ensuring the construction node of the owner. At the same time, during the construction process, we firmly implemented the policy of safety first and prevention first, strengthened the safety management, and no safety accident occurred during the implementation of the project.
During the whole construction process, the project department attached great importance to environmental protection, designated a person responsible for environmental protection, responsible for the management and coordination of the environment around the construction and construction site, and regularly inspected the environment of the construction area, no environmental pollution accident occurred. Through the efforts of all the staff of the project department, the construction safety and quality were ensured, and the construction task was successfully completed, which was well received by the owner and the general contractor design institute unit.
