Talking about static pressure pile driver construction? Under normal circumstances, how do construction company personnel carry out static pressure pile driver construction, and what is the basic operation and construction technology like? The following is the content related to the professional construction terminology of static pressure pile machine construction compiled by the editor of Zhongda Consulting. The basic situation is as follows:
Static pressure pile is a method of engineering pile foundation construction. The static pressure pile method construction is through The pile driving mechanism of the static pile driver uses the self-weight of the pile driver and the counterweight on the frame to provide reaction force to press the prefabricated piles into the soil.
Static pressure pile driver construction steps:
1) Site leveling: Remove surface debris, fill in potholes on the site, and use a road roller to compact the topsoil if necessary. And dig ditches along the perimeter of the site to drain water into the water collection pit for centralized drainage.
2) Measurement and positioning: Before starting work, Party A is required to provide information on control points in the area and clarify the specific locations of on-site control points, and handle handover procedures between both parties in a timely manner. According to the control points provided by Party A, the axis and pile positions are laid, short steel bars are inserted at each pile point, and a pipe pile equal diameter mold is made, and white ash is spread along the mold. Retest after the pile driver is in place. Special personnel are responsible for the measurement, positioning, setting out and review work. The measuring instruments should be inspected regularly and the original data of measurement, positioning and setting out should be prepared. The resulting positioning and setting-out measurement results shall be reported in writing to the supervisor and Party A for review and inspection. The axis deviation shall not be less than 1cm and the pile position deviation shall be less than 2cm. Construction can only begin after confirmation.
3) Finished product inspection of prestressed pipe piles: Check the factory certificate and main quality indicators (concrete strength) of the prestressed pipe piles, then conduct a visual inspection, and make inspection records. It shall be accepted by the supervisor and signed for approval. Both ends of the pipe pile should be cleaned. If there is paint and debris contamination on the welding surface, it should be cleaned. Unqualified piles will be cleared out of the venue in a timely manner.
4) Check the equipment readiness: Install the pile driver in place, configure the ballast according to the required total weight, and level the pile driver platform. Carefully check the pile driver equipment and lifting tools before piling.
5) Pile detection: According to the measured positioning points, use a steel pipe of the same diameter to press through the ① layer of fill soil with a static pile driver to detect obstacles in the surface soil. Prevent the pile tip from clogging the rocks so that it can pass through the ② layer of silt smoothly. If the soil condition of the site is in good condition, in order to improve work efficiency, you can directly press piles without exploring piles.
6) Hanging pile insertion: Select the pile length of each section and the pile pressing sequence and number them according to the designed pile length of each hole. Use the pile driver's own crane to hoist the piles into position in numerical order, and then use the clamp to hold the piles and insert them into the holes at the measured positioning points. It is very difficult to correct the angle of the pile during the driving process, so it should be set correctly when it is in place. When the first section of pipe pile is inserted into the ground, the position and direction must be maintained correctly. Press lightly at the beginning and check carefully. If there is any deviation, correct it in time. If necessary, pull out the heavy pressure. The verticality of the piles is arranged to be monitored by a dedicated person using two theodolite. The theodolite should be set in a place that is not affected by piling, and in a direction of approximately 90° to each other, and should be leveled frequently. The monitoring guide frame should be kept vertical, and the theodolite should be guided by the pile driver. Adjust the rotation, sliding and stopping of the rack.
7) Pile pressing: The weight of the pile driver is used to hold the pile by the hydraulic system to vertically press the pipe pile into the soil, and two theodolites are used to bidirectionally control the verticality of the pipe pile at any time. And observe the pressure and depth of pile pressing. If the amount of sinking is large during initial pressure, light pressure should be used. As the pile sinking deepens, the sinking speed slows down and the pressure gradually increases. During the entire pile pressing process, the pressure rod, pile cap, and pile body should be kept on the same axis as much as possible. If necessary, the direction of the guide rod of the pile frame should be adjusted according to the direction of the pile body. Pay attention to try not to subject the pipe pile to eccentric pressure to prevent the pipe pile from bending. When it is difficult to sink the pile under pressure, it is necessary to check whether the pile frame guide rod is tilted and eccentric, and whether the pile body is vertical. Each pile should be completed continuously to avoid difficulty in continuing to press down. Draw a pile position numbering map according to the designed pile position plan, prepare your own pile pressing records, and submit one copy each to Party A and the supervisor for supervision and inspection. Select the floating observation point at the pile position and make detailed records.
8) Pile feeding: In order to press the pipe pile to the design elevation, a pile feeding device is required. The pile feeding device is made of steel plate and is 11m long. During operation, first lift the pile feeder. The lower end surface of the pile feeder is close to the upper end surface of the upper pipe pile. The center line is aligned to ensure that the verticality meets the requirements and then pressurized until the pile is sent to the design elevation.
Precautions for static pressure pile driver construction:
1. When the final pressure value is limited by various conditions and cannot reach the final pressure value estimated based on local experience, it is advisable to The characteristic value of the vertical bearing capacity of a single pile should be reduced according to the actual situation. The number of repressurizations should not be increased arbitrarily. The stabilizing pressure during repressurization should not be less than the final pressure, and the stabilizing time should be 5-10s.
2. For static pressure piles with pile foundation design grades of B and C, the final pressure standard must be tested by on-site pressure test piles, and there is little local construction experience and has not yet been established to meet local conditions. When the final pressure value is related to the characteristic value of the vertical bearing capacity of the pile, the final pressure standard of the static pressure pile sinking can be based on the design pile length and elevation. The final pressure can be used as a reference. 2-3 piles can be constructed before construction. After 24 hours, the pile should be repressed with a pile pressure equal to the ultimate bearing capacity of the pile. If the pile body does not sink, full construction can be carried out according to the designed pile length and elevation. Otherwise, adjustments should be made.
3. When the pile end bearing layer is weathered rock (soil) layer softened by water, the pile driving construction should be based on the design requirements for pipe pile end sealing concrete construction.
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