Down-the-hole drill for construction of steel (Nov 28, 2022)
Original Title: Down-the-hole Drill for Steel Pipe Pile Construction Summary of steel pipe pile construction of Xiaoxi Bridge in expressway from Dejiang to Wuchuan in Guizhou Province. This paper makes a comprehensive evaluation of the technology, quality inspection standards and methods in the construction of steel pipe piles, so as to determine the best technology and construction method, establish a model project for the future, guide the large-scale construction of subsequent steel pipe piles, and prevent the quality and safety problems that may arise in the subsequent construction and production. Construction summary The abutment of Wuchuan bank of Xiaoxi Bridge is provided with a pile foundation to effectively transfer the load to the middle of the slope and reduce the impact on the bank slope; the accumulation body at the lower part of the cliff is supported by an anti-slide pile foundation. There are 4 anti-slide piles and 25 steel pipe piles. The steel pipe pile is a D245 × 10mm steel pipe, with a bundle of steel bars placed in the center. Each bundle is composed of three D28 steel bars. The pile top is connected by No.16 I-steel to form a framework, and the pipe is filled with M7.5 cement mortar. In the first project, the steel pipe pile A-1 of the left 2 # pier of Xiaoxi Bridge is 20m long, the diameter of the steel pipe pile is D245 × 10mm, the design concrete strength is M7.5, and the concrete volume is 9.4m3. The construction equipment includes 10 sets of Hongwuhuan high wind pressure down-the-hole drills, 4 sets of air compressors, 2 sets of GY100 engineering drilling rigs, 2 sets of cranes, 1 set of generators, and 3 sets of concrete transport vehicles. Construction process flow of steel pipe pile: Clear the site around the pile hole, position the steel pipe pile, mining dth bit , put the down-the-hole drill in place, form the hole for the steel pipe pile, clean the bottom of the hole for the lower steel pipe and grout the steel pipe to clear the site and demobilize. 1. Clean the site around the pile hole According to the actual site, the site around the pile hole shall be cleared, and the construction platform shall be erected. The platform shall be firmly erected at the opening of the pile hole and can bear 2 t heavy engineering drilling rig. 2. Positioning of steel pipe pile During construction, professional surveyors and constructors shall be organized to arrange the positions of steel pipe piles according to the requirements of design drawings and in combination with the actual situation on site, and the positions shall be marked with red paint. 3. Drilling rig in place Expand the full text After the engineering crane lifts the drilling rig to the working platform, the drilling rig shall be adjusted according to the hole position of the steel pipe pile. 4. Steel pipe pile pore-forming The construction of steel pipe pile hole formation shall be carried out according to the drawing design and relevant technical specifications. A special 100 type drilling machine is used to drill holes according to the requirements of the design drawings. The hole diameter is controlled to be 273mm, with an allowable error of ± 1 °. In order to ensure the depth of the hole, the depth of rock into the bearing stratum is required to be 200mm greater than the design depth. 5. Hole cleaning at the bottom of steel pipe pile The diameter of the steel pipe pile this time is 245 mm, and it will be difficult to clean the hole by conventional measures. Therefore, when the drilling is nearly completed, the depth of the hole shall be measured with a measuring rope to prevent the drilling depth from failing to meet the design requirements and to avoid errors in the placement of the steel pipe. After the completion of the hole, the sediment at the bottom of the hole shall be cleaned with a special bottom cleaning drill for engineering geology to avoid sediment at the bottom of the holes. 6. Steel pipe pile construction: The diameter of the steel pipe pile in this project is D245 × 10mm, and the length of the steel pipe pile is designed to be 20m. According to the design requirements, the pile length shall not be less than 1/2 when passing through the corrosion groove and entering the complete bedrock. Before lowering the steel pipe pile, the rust, oil stain and other dirt at the end of the steel pipe pile shall be carefully checked and must be removed, and the pile body shall be checked for cracks or damage. If there is any damage, the pile shall not be lowered before reasonable treatment. Anti-corrosion and anti-rust treatment measures shall be taken for the outside of the pile body (such as brushing two layers of anti-rust paint). After lowering the pipe, M7.5 cement mortar shall be injected into the pipe. Quality control during the construction of steel pipe pile: the deviation of pile position shall be controlled within ± 50 mm; the flatness of each pipe end shall be ≤ 5 mm; the pile insertion position shall be correct and the verticality shall be less than 0.5%; 7. Steel pipe pile grouting: the pipe is filled with M7.5 cement mortar. 8. Construction of lower steel pipe pile: repeat the above steps (3)- (7). 9. After drilling, remove the construction platform,mining dth bit, clean the site and prepare for demobilization. After the construction of steel pipe piles is completed, the bearing capacity shall be tested by static load test. The number of piles to be tested shall not be less than 1% of the total number, and shall not be less than 3. Return to Sohu to see more Responsible Editor:. wt-dthtools.com
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