Otherwise, the ultimate bearing capacity at the pile tip may be greatly reduced because the sedimentation is too thick and soft.
After the completion of the drilled pile, the hole depth, hole diameter and inclination shall be checked, and the hole can be cleaned only after meeting the specification requirements.
Inaccurate elevation of pile casing top may cause short pile accident and insufficient bearing capacity of pile; If the measuring line is wrong, the removal and lifting of the tremie will be wrong when pouring underwater concrete, resulting in pile breaking accident.
It shall have sufficient stiffness and qualified welding quality.
3.
4.
The rubber ring of the conduit joint must be intact and tight without water leakage.
These works shall be carried out quickly to avoid too long interval and too thick sediment of drilling slag, resulting in difficulty in hole cleaning or hole collapse.
3.
These quality problems often make it difficult for the pile to meet the design requirements and remedy.
The pile casing shall be embedded firmly.
During the pouring process, the buried depth of the conduit shall be 2 ~ 6m.
（3） Mud preparation 1).
1、 Quality control objective the construction quality control of bored cast-in-place pile must achieve the following objectives: ① various indexes in the pile forming process, including pile position, pile length, pile diameter, sediment at the bottom of the hole, perpendicularity of the final hole and pile forming quality, can meet the design requirements; ② The strength of reserved concrete test block meets the specification requirements; ③ The pile body is complete, homogeneous and continuous without mud inclusion, pile breaking and other defects; ④ The ultimate bearing capacity of pile meets the acceptance index specified in the code.
Friction piles shall not be cleaned by deepening the drilling depth.
In order to accurately control the drilling depth, a control ruler shall be made on the frame or steel wire rope for observation and recording during construction.
The height of pile casing top shall meet the specification requirements: (1) the height of pile casing top shall be 0.3m higher than the ground; (2) .
（4） Drilling rig in place 1.
（6） Supervision control points for fabrication and installation of reinforcement cage 1.
In order to prevent the reinforcement cage from sinking or floating up under the influence of buoyancy on the concrete, necessary processes and measures must be taken to prevent the reinforcement cage from floating up after the reinforcement cage is in place.
3) .
Embedding requirements of pile casing 1.
2.
During hoisting, double safety shall be adopted for the steel wire rope, and double steel wire ropes shall be adopted to prevent the rope from sliding or breaking.
When the drilling rig is in place, it must be kept stable without inclination and displacement.
4.
By reviewing the design drawings, master: (1) hydrological and geological conditions, and select appropriate drilling machines and tools, drilling speed, mud performance, etc; (2) .
During the construction process, it is easy to have quality problems such as excessive deviation of pile position, excessive sediment at the hole bottom, floating of reinforcement cage, segregation of pile concrete, broken pile and mud inclusion.
the height of pile casing top shall be 1.0 ~ 2.0m higher than the water surface; When there is confined water in the hole, it shall be more than 2.0m higher than the stabilized confined water level, otherwise it is easy to cause hole collapse.
During drilling, carefully observe and check whether the pile hole is vertical.
2.
requirements for pile foundation type, pile diameter, pile bottom sedimentation thickness, pile foundation reinforcement, final hole principle, etc; (3) Understand the design overview of substructure and superstructure, and carefully review the size, elevation, reinforcement quantity and diameter, concrete design strength, etc.
Hole cleaning methods include slurry replacement, slurry pumping, slag removal, air compressor spraying, mortar replacement, etc.
2.
The supervisors must pay attention to the quality monitoring of the whole construction process.
2.
It can be said that there are many kinds of projects, high technical content and many influencing factors.
Deformation shall be avoided during reinforcement cage handling and hoisting; Before placement, the condition in the hole shall be checked by a hole detector to ensure that there is no collapse and shrinkage in the hole; The reinforcement cage shall be placed in alignment with the hole position, firmly, slowly and straightly to prevent collision with the hole wall.
The hanging height of the conduit from the hole bottom should be 25 ~ 40cm.
The joint and bottom of the acoustic pipe shall be sealed, and the top shall be closed with a wooden plug to prevent mortar and sundries from blocking the pipe.
in the pile foundation design drawings.
When pouring to the pile top, there must be sufficient flushing height to ensure the buried depth of the conduit and the compactness of the concrete.
When butting the reinforcement cage, at least two people are required to work at the same time for reinforcement alignment and sleeve installation, and they are close to each other.
2、 Key points of supervision control in construction preparation stage 1.
If it is a friction pile, the friction coefficient around the pile will be significantly reduced and the bearing capacity of the pile foundation will be reduced; When the relative density of mud is small and the mud skin on the hole wall is thin, it is easy to cause accidents such as hole expansion, hole collapse and even buried drill head.
Pay attention to safety to prevent them from squeezing into the pile hole.
7、 C30 concrete for underwater concrete pouring shall have good workability, no obvious segregation and bleeding during transportation and pouring, and the slump shall be 180 ~ 220mm.
The acoustic pipe shall be set in strict accordance with the design drawings.
After reaching the design position, it shall be fixed with hanging reinforcement.
4.
Carefully review the design drawings.
The large hopper must have sufficient volume to ensure that the buried depth of the conduit after the first batch of concrete pouring is not less than 1m.
Reinforcement cage hoisting and installation.
3.
The mobilized reinforcement shall be used only after passing the sampling inspection and test, and the fabrication of reinforcement framework shall meet the requirements of design and specifications.
2) The, sedimentation tank and slurry storage tank shall be set separately, and the circulating slurry can enter the slurry storage tank after sedimentation.
Pay attention to the elevation of the reinforcement cage.
3.
at present, slag removal is mostly used for hole cleaning on site.
In case of inclination, it shall be corrected in time.
Source: the bored cast-in-place pile under the supervision of Zhulong is a concealed project with many pile forming links, which is prone to quality accidents in the construction process.
4) The relative density of mud shall be properly adjusted according to the actual situation; When the hole is formed in the soil layer passing through the sand pebble layer or easy to collapse, the relative density of the mud shall be increased accordingly.
Pier cage and torsion cage are strictly prohibited.
The detection pipe joint generally adopts casing, and the hydraulic clamp shall be pressed and tightly sealed after the sleeve connection, and the quality shall meet the specification requirements.
waste slag shall meet the requirements of civilized construction.
Construction preparation, hole completion, hole cleaning and In order to ensure or improve the pile quality of bored cast-in-place pile, the quality monitoring of all links in the whole process of reinforcement cage connection, hoisting and underwater pouring and various effective preventive measures should be taken.
Safety measures during hoisting 1 during hoisting, the commander shall clean up non construction personnel within the hoisting range to avoid injury to human body caused by reinforcement cage.
Carefully recheck the top elevation of pile casing and the scale of measuring rope.
According to the experience of supervising the quality of bored pile, some key points of quality control are summarized.
Before the tremie is used, its quality indexes shall be carefully checked and tested, and it can be used only after it is qualified.
5) When the mud is too thick, the drilling speed is slow, the hole cleaning time is long, and the mud skin on the hole wall is thick.
When the concrete is transported to the construction site, its uniformity, slump and other indicators shall be checked.
2.
Lifting rings shall be set at the top of the framework.
During the pouring process, the buried depth of the conduit shall be controlled at 2 ~ 6m..
The existing problems cannot be judged completely through post inspection.
Operation safety of straight thread forming machine: The operation safety of the straight thread forming machine shall comply with the relevant provisions of the operation manual of the steel bar rib stripping and rolling straight thread forming machine.
Cushion blocks to control the thickness of protective layer shall be set outside the framework, such as circular concrete precast blocks or ear shaped reinforcement, with a vertical spacing of 2M and no less than 4 places around the horizontal.
Therefore, the mud index shall meet the specification requirements.
The mud pit shall be large enough, which shall be determined according to the pile length, hole diameter and practical experience.
4.
The construction of bored cast-in-place pile includes not only measurement, but also mechanical operation, reinforcement processing, concrete and pouring.
The long skeleton shall be fabricated in sections, and the section length shall be determined according to the hoisting conditions to ensure no deformation, and the joints shall be staggered.
After hole cleaning, before pouring concrete, the sedimentation thickness at the hole bottom shall be checked to meet the design and specification requirements before pouring underwater concrete.
hole cleaning 1.
The installation of tremie requires that the underwater concrete is generally poured with steel tremie, and the inner diameter of the tremie is 200 ~ 350mm.
4、 Drilling v.
