3.
2、 According to the construction characteristics, difficulties and construction period requirements of prefabricated pipe piles, the construction organization of prefabricated pipe piles shall establish a management organization with the project management department as the core, implement it by sections, organize a strong professional construction team and equip with modern construction machinery and equipment, so as to ensure that the project can be completed on time and with quality on the premise of safety.
6.2 setting out of pile position the prefabricated pipe pile shall be constructed in sections according to the section of the construction drawing.
If the compaction quality cannot meet the requirements of mechanical construction, 30 ~ 50cm chemical improved soil (mixed with 3% lime improved soil) shall be replaced.
6.8 the technical parameters of the final pressure of the final pressure precast pipe pile construction generally adopt double control.
2.
During static pressure pile construction, load shall be equipped according to about 2 times of the bearing capacity of single pile required by the design However, the maximum load shall not exceed the stress that the pile can bear.
In case of any of the following situations, the construction shall be suspended, and the construction can be carried out only after analysis and research and measures are taken: ⑴ sharp change in penetration; ⑵ broken pile head or cracked pile body; ⑶ sudden inclination and displacement of pile body; ⑷ serious uplift of nearby ground; ⑤ floating of adjacent piles or water at pile position The horizontal movement is too large; (6) the bearing capacity of single pile has met the design value, and the pile pressing length cannot meet the design requirements; (7) the static pile pressing machine is jacked up due to insufficient load.
6.5 for verticality adjustment, use the total station with the hammer ball to observe the verticality of the pile Perpendicularity: the perpendicularity of the pile insertion shall not be greater than 0.5%.
6.9 after the machine moves and presses the piles to reach the control elevation and the final pressure meets the design requirements, the machine body moves back and forth to the next pile for construction, and it is strictly prohibited to roll the machinery directly on the constructed engineering piles.
If any deviation is found, adjust it in time and insert it again if necessary.
⑵ the final pressure meets the design requirements Design (2.0 times design single pile bearing capacity ≤ final pressure ＜ pile ultimate bearing capacity) Requirements.
Loading and unloading shall be handled with care, and throwing, collision and rolling are strictly prohibited.
The weld must be full without slag inclusion or pores.
When sinking the pile within 5m from the ground surface and after the pile end enters the bearing layer, slow pressing must be adopted, which is common to the stratum The pile sinking speed shall be controlled within 1.5 ~ 2m / min.
In order to ensure the quality of welded piles, it shall be: ① the end face of pile extension shall be flat, the upper and lower piles shall be welded firmly, and the surrounding shall be spot welded first Positioning and fixing (if there is a gap between the upper and lower piles, it shall be filled with iron sheets and welded firmly) ② remove sundries and oil stains on the end face; ③ align the upper and lower planes, and keep the upper and lower pile sections straight with a dislocation deviation of 2mm during pile connection; ④ weld symmetrically in layers after the upper and lower pile sections are fixed.
The bench mark shall be set outside the scope affected by piling, and the ground elevation of pile position in the construction section shall be measured.
Ensure that the surface of the construction site shall have sufficient compressive bearing capacity.
3.
It is not allowed to use strong pulling to quickly correct the deviation and make the pile body crack and break.
6.6 when sinking the first section of prefabricated pipe pile, observe while pressing the pile.
pre cast pipe pile construction process and process flow 6.1, pre cast pipe pile construction process 6.2, pre cast pipe pile process flow chart, personnel training and technical handover before construction, and arrange construction technicians to be responsible for on-site construction records during construction, Collect relevant data, carefully record the response of the equipment when penetrating into the stratum during construction, and timely record the reading of the pressure gauge.
6.1 site leveling (1) general section: remove surface attachments on the construction site and dig out tree roots.
(2) fish pond or low-lying ponding section: for fish pond or low-lying ponding section, dig drainage ditch for drainage or centralized pumping treatment to drain the ponding and remove the residual garbage at the base.
construction preparation of prefabricated pipe pile 1.
The construction site is provided with 2% ~ 4% transverse drainage slopes, and temporary drainage ditches are set on both sides of the subgrade to ensure smooth drainage and avoid soaking the subgrade base due to rain and affecting the construction.
Source: China railway information is only for reference and study.
Ensure the “three supplies and one leveling” of the site before commencement, especially the power supply.
The survey control network and bench mark shall be arranged.
It shall be tested according to the specification requirements, and can be used only after passing the inspection.
3、 Pre cast pipe pile construction personnel allocation and responsibilities IV.
The precast pipe pile stacking site shall be solid and flat, and simply supported on sleepers according to two fulcrums at 0.21l at both ends to ensure uniform stress on the pile body.
VII.
The number of stacking layers of rigid piles shall not exceed 3.
The on-site technician shall use the steel ruler method to arrange the piles according to the layout and control points, insert bamboo chopsticks into the pile position and sprinkle white ash around (or bind red cloth strips) to make the ground mark of the pile position obvious.
When lifting the prefabricated pipe pile, use cloth to lift it to the side of the pile machine, start vertical lifting, stably send the pile to the pile holder of the pile pressing machine, align the center of the rigid pile with the pile position, start the pile oil pump to hold the pile, fix and press down the prefabricated pipe pile, and slowly press it down and insert it into the soil for about 50cm.
VIII.
I.
Carefully study the engineering geological data, and prepare the implementation organization plan according to the specifications and procedures, combined with the project progress, cost and feasible construction requirements such as safety, quality, environmental and water conservation.
The unqualified products shall be marked and cleaned out of the site.
After the base is dried, the lime soil shall be backfilled in layers and compacted layer by layer to ensure that the static pressure construction requirements of prefabricated pipe piles are met.
When the prefabricated pipe piles are transported to the construction site, a special person shall be responsible for inspection and acceptance, Check the factory data and the factory certificate of prefabricated pipe pile (certificate number; specification, length and wall thickness of prefabricated pipe pile; concrete strength grade; dimensional deviation; manufacturer’s name, license date and factory date; signature or seal of inspector (can be expressed by inspector code)) Count the length, specification and quantity.
4.
The soft soil section affecting the operation of pile driver shall be compacted.
6.3 after the commissioning of the pile machine in place equipment, use the walking device and mobile walking on the pile machine to put it in place, and equip the load according to no less than 2.0 times the bearing capacity of a single pile, and the maximum load shall not exceed the stress that the pile body can bear.
6.4 the precast pipe pile shall be lifted in place.
selection of static pile driver parameter table VI.
Construction quality control and detection of prefabricated pipe pile 8.1 Quality control (1) technical preparation: carefully get familiar with the review drawings and do a good job of technical disclosure (pile position review, pile pressing, welding, etc.) (2) select qualified manufacturers to supply prefabricated rigid piles.
6.7 the upper and lower precast pipe piles of pile extension shall be welded with carbon dioxide gas shielded welding.
Before the hoisting of the precast pipe pile, the size mark shall be set on the pile body (one channel is set every 1m) In order to observe and record during construction.
Record the reading of the instrument every 1m or when the reading of the pressure gauge changes suddenly, and record the pile forming depth and final pile pressing force.
See the construction organization chart on the next page for details.
For “false limit” and “suction” 5.
During pile connection, the lower pile shall be reserved about 1m from the ground, and each pile shall be naturally cooled to natural temperature after welding (after welding, it shall be cooled naturally to the natural temperature, generally not less than 8min.
Pile sinking shall be carried out continuously and shall not be stopped halfway.
After the site is leveled, the survey team shall control the setting out, and use the total station or GPS to accurately set out the outermost four pile positions (insert steel chisel) of each section as the control points.
⑴ the length of the pressed pile reaches the design requirements, and the elevation of the pile top is controlled by a level with a deviation of ± 50mm.
2.
⑶ stack them at the designated position of the construction site and minimize secondary transportation to avoid damaging the rigid pile pipe..
main construction machinery allocation v.
Precautions for the construction of prefabricated pipe piles.
1.
4.
Select a qualified pipe pile manufacturer and organize the mobilization of materials.
According to the design requirements, the pile length control is supplemented and the static pressure control is mainly adopted.
It is strictly prohibited to use water for cooling and pile sinking immediately after welding) After the acceptance of the project by the supervisor and on-site technicians, the next work can be carried out only after passing the acceptance.
Investigate the site, investigate the surrounding structures and pipelines, reasonably arrange the site, and plan the construction sequence and mechanical walking route.
⑶ check the pile pressing records one by one to ensure the authenticity of the pile pressing records.
after the pile sinking process meets the hard interlayer or enters the bearing layer, it shall be controlled within 1.0m/min, otherwise the pile head will be broken due to too fast pile sinking speed.
