At this time, the pile must be supplemented again or the designer shall be asked to approve the excavation on the foundation structure Take reinforcement measures Catheter evacuation In the process of concrete pouring, the tremie is separated from the concrete surface, and mud and water enter the tremie, resulting in smaller pile body or broken pile.
When pouring concrete again, the lower concrete has hardened and the conduit cannot be pulled out.
1.2 treatment method 1) the “floating cage” appears at the beginning of pouring concrete , mainly due to the hanging belt between the conduit and the cage; the concrete pouring shall be stopped immediately and the conduit shall be shaken up and down repeatedly or rotated in one direction.
2) during concrete pouring, the relative density of mud is too high, there is mud inclusions between the concrete and the main reinforcement, and groundwater emerges along the mud inclusions.
2) Avoid the conduit hanging with reinforcement cage.
2) when the conduit is vibrated up and down, the conduit is hung with reinforcement, a great external force is applied to the reinforcement, and the lifting ring is loose.
4) during pile cutting, generally control the distance between the pile cutting part and the design pile head to be about 1m, and the length of this 1m section The concrete shall be chiseled manually, and it is strictly forbidden to repair it with air pick and other machinery.
3) measures to prevent hole wall collapse: the original soil depth of the pile casing shall be at least 1m.
5.3 treatment methods If the pile position exceeds the allowable deviation range of the specification, it shall be approved by the designer and necessary reinforcement measures shall be taken; if it is a single pile foundation, the pile shall be supplemented again.
2) quickly put forward the conduit, reset the water barrier ball, and wash out the conduit Continue to lower the tremie until the tremie cannot be inserted, slightly lift the tremie and continue to pour concrete Buried pipe In the process of pouring concrete, the conduit is buried in the concrete and is not pulled out in time.
3) the hole wall collapses and a large amount of mud and sand buries the conduit during concrete pouring.
During concrete pouring, the reinforcement cage falls and the reinforcement skeleton is lower than the original design position, commonly known as “sinking cage” 2.1 cause analysis 1) the welding between the hanging reinforcement and the main reinforcement or between the segmented reinforcement is not firm or the lifting ring falls off.
2) when the pile head laitance is chiseled out after the foundation pit is excavated, the cage sinking is found, but the sinking depth is unknown.
3.3 treatment methods 1) when the conduit is empty, quickly insert the conduit into the concrete, use a small water pump or small-diameter pumping equipment to pump out the water in the conduit and continue pouring concrete.
After the concrete hardens, waste piles are formed.
2) the conduit is hung by the reinforcement.
2) if the quality of the pile body is seriously deficient In case of sinking, the design and testing center shall be asked to verify whether it is necessary to refill the pile…
3.2 preventive measures Strictly control the lifting speed of the conduit.
2) open the foundation pit The excavated earth shall be excavated in layers, and the depth of each excavation shall be controlled at about 4m.
2) during the installation of the reinforcement, the skeleton is distorted, the stirrup is deformed, the desoldering falls off or the conduit is inclined, making the reinforcement in close contact with the outer wall of the conduit.
Part 6 Water gushing from pile head After the foundation pit cushion concrete is poured, water seepage occurs at the pile head.
2) strictly control the relative density and consistency of slurry to keep it within the allowable range of specifications.
2) during the excavation of the foundation pit, the one-time excavation depth is too large, and the lateral pressure of the soil causes the pile dislocation.
3) sometimes due to the failure of machines and tools Barrier, stop when pouring concrete, the concrete between the tremie and the reinforcement has solidified, and bring out the reinforcement when lifting the tremie.
3.1 cause analysis The construction personnel make mistakes in operation and pull out the conduit too fast.
2) in the process of concrete pouring, the cage floats up with the conduit pulled out, but the concrete surface does not move.
3) in the process of concrete pouring, with the concrete surface When the cage rises, the concrete pouring volume and speed shall be controlled Sinking cage The reinforcement has been sunk to the design depth.
However, from the beginning of drilling to the end of pile completion, due to the influence of many factors, it is very easy to cause quality problems and even quality accidents.
4.2 preventive measures 1) the initial setting time of concrete must be twice the normal pouring time.
2.2 treatment method 1) if the depth of the cage into the concrete is not deep (less than 2m) After the foundation pit is excavated, manually or mechanically excavate the soil on the original pile position, Chisel out the pile head reinforcement and connect it.
Retarder shall be added during construction in summer to ensure the continuous supply and pouring of concrete.
During the lifting and sinking of the conduit, the flange is hung with the reinforcement cage.
4) during pile cutting, the air pick and other machinery excessively impact the concrete at the pile head, resulting in cracks and water seepage in the concrete at the pile head.
The slurry concentration shall not be too low, and it is strictly prohibited to put clean water into the hole.
2) if the conduit cannot be pulled out when embedded in the concrete, it is generally discarded, and the pile shall be supplemented after being approved by the designer.
Before lifting, measure the height of the concrete surface, calculate the length of the conduit embedded in the concrete and the height that can be lifted this time.
Once the conduit is separated from the reinforcement cage, the cage will sink into the hole.
Part1 Steel cage floating For the reinforcement skeleton that has been sunk to the design depth, during concrete pouring, the skeleton position is higher than the original design position, which is commonly known as “floating cage” “1.1 cause analysis 1) the spacing between the inner diameter of the reinforcement cage skeleton and the conduit is small, the particle size of coarse aggregate is too large, and the lap welding head of the main reinforcement is not welded flat.
6.3 treatment methods 1) if water is found at the pile head, the testing unit shall be asked to measure the concrete strength of the pile body and whether there are defects in the pile body.
4.1 cause analysis 1) the initial setting time of concrete is short or construction machines and tools are used 、 The interval time is long due to power supply and other reasons.
For hole forming construction next to adjacent piles that have just been poured, the distance shall not be less than 4 times the pile diameter, or the minimum interval shall be more than 36h.
6.1 cause analysis 1) the concrete pouring is not dense, and the pile body (especially the pile head) There are cracks or mud inclusions.
The stone particle size in the concrete is too large and the grading is uneven.
4) the pouring speed is too fast, and the concrete surface rises to the bottom of the reinforcement cage, resulting in upward “buoyancy”, resulting in the floating of the reinforcement cage.
Also due to the hanging belt between the conduit and the cage, the conduit shall be shaken repeatedly and moved up and down repeatedly to cut off the connection between the two.
5.2 preventive measures 1) improve the professional level of the construction personnel, enhance the working center, and the drilling positioning is accurate.
3) during foundation pit excavation, the excavation machinery collides with the pile body, resulting in cracks at the pile head.
Part 5 Large deviation of pile position After the foundation pit is excavated, check the pile position against the axis, and the deviation of the pile position exceeds the allowable range of the specification.
5.1 cause analysis 1) there is deviation in the setting out of the construction personnel or the mechanical drilling positioning is inaccurate.
3) during earthwork excavation, it is strictly prohibited for excavation machinery to collide with the pile body.
4.3 treatment method 1) when the conduit is hung with strip steel Reinforcement cage: if it is found that the reinforcement cage is not deeply embedded in the concrete, the reinforcement cage can be lifted and the conduit can be rotated to separate the conduit from the reinforcement cage, otherwise the conduit has to be abandoned.
The tremie should be vibrated up and down frequently during pouring and tamping.
Source: if there is infringement in Zhulong forum, please contact to delete it Bored cast-in-place pile has the advantages of low construction noise, low vibration, free transformation of pile length and diameter according to the design requirements, reliable entry of pile tip into the bearing layer, large bearing capacity of single pile and so on.
The pile head concrete must be roughened, and then pour the concrete with a strength grade higher than the original grade.
6.2 Preventive measures 1) strictly control the concrete quality.
The particle size of coarse aggregate should be 5 ~ 25mm.
If cracks occur only within a section of the length of the pile head, the concrete at the pile head shall be chiseled until solid concrete is exposed, and then the concrete with a strength grade higher than the original grade shall be poured.
According to the soil characteristics on site, the wall protection slurry shall be selected correctly.
Therefore, quality control has become a difficulty in construction.
