Technical Measures for Prestressed Pipe Pile Construction
2013-12-04
873
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(1) During construction operations, the pile driver operator must follow command signals and must not leave the work post at will. The operator should constantly monitor the mechanical operation and immediately inspect and address any abnormalities;
(2) Piles may be transported and driven only after reaching 100% of the design strength;
(3) When lifting and transporting piles, the lifting points must meet the design requirements, and special tools shall be hooked at both ends for lifting;
(4) Pile stacking shall meet the following requirements:
1 The site shall be level and solid, with no uneven settlement; if necessary, the stacking yard shall be hardened;
2 The positions of the dunnage shall be the same as the lifting points and shall remain in the same plane;
3 Piles of the same specification shall be stacked together, with pile tips facing one end to facilitate construction;
4 When stacking pipe piles, dunnage must be placed under the bottom layer, and the pipe piles at the edges of the dunnage shall be wedged tightly with wooden wedges to prevent rolling. The number of stacked layers shall not exceed 4;
5 When stacking pipe piles in layers, two rows of dunnage shall be placed on the ground perpendicular to the length direction of the pipe piles, and the dunnage shall be located at 0.2 times the pile length from the pile ends respectively;
(5) Before pile sinking construction, the site soil conditions shall be understood, and the pile sinking equipment shall be inspected and tested. The foundation on which the pile driver travels shall have sufficient bearing capacity and be level, so as to ensure vertical pile driving during pile sinking;
(6) The pile manufacturing quality shall meet the requirements of design and construction specifications. During pile sinking, care shall be taken at all times to keep the pile under axial compression; any deviation shall be corrected promptly to avoid pile head crushing and pile breakage accidents;
(7) During pile splicing, the axes of the upper and lower pile sections shall be kept aligned, and the splicing time shall be shortened as much as possible;
(8) The force-measuring instruments used in static pressing pile sinking shall be regularly maintained, serviced, and metrologically calibrated to reduce detection errors. During construction, detection records shall be carefully kept as the pile driver sinks;
(9) During pile sinking, when the pile tip encounters a hard soil layer, sand layer, or gravelly sand layer containing pebbles and the pile sinking resistance suddenly increases, or even exceeds the maximum static pressing capacity of the pile driver and causes the pile driver to lift, the maximum static pressure shall be applied to the pile, and an intermittent impact pressing method of alternating stop and press shall be adopted to make the pile sink slowly until it penetrates the hard soil layer, sand layer, or gravelly sand layer containing pebbles;
(10) When the pile sinks to near the design elevation, pressing shall not be stopped too early, so as to avoid the phenomenon of stopping sinking or difficulty in sinking to the design elevation during supplementary pressing;
(11) When the pile sinking resistance exceeds the maximum static pressure of the pile driver, or when the pile driver tilts significantly upward due to insufficient time to adjust the counterweight, the machine shall be stopped immediately and corresponding measures shall be taken to avoid pile breakage or other accidents;
(12) When the upper soil layer around the pile is saturated muddy soil or cohesive soil, observation points shall be set at about 10% of the total number of piles during pile pressing construction, and a level and theodolite shall be used to regularly detect the upward displacement of the pile and the deviation of the pile top.
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