How to use the drilling coring method to detect the quality of the pile

The core drilling method is to drill the core sample from the pile concrete to determine the quality and strength of the pile concrete, which has the advantages of short construction period, small damage to the pile, comprehensive and reliable data obtained, good economic effect and easy to take remedial measures when the problem is found. Because this method is more intuitive, it can not only observe the pouring quality, mix ratio, sand, stone and cement mixing uniformity of concrete through coring, verify the length of cast-in-place piles, but also correctly judge and check the thickness of sediment at the bottom of the pile, the diameter reduction, the mud inclusion, the condition of concrete and the bedrock at the bottom of the pile. If the borehole passes through the appropriate depth of the pile bottom, the condition of the bearing layer at the end of the pile can be further ascertained, and whether there is a weak interlayer under the bearing layer can be checked.

It can also be used to check whether the actual diameter of the enlarged end of the belled pile meets the design requirements. However, due to the small core sample of the bored coring method, the local defects of the cast-in-place pile are often difficult to find, and the verticality of the drilling is very strict, the core recovery rate is very high, and the construction requires a high level of operation, which should be completed by skilled staff, and should comply with the relevant national regulations on safety technology and labor protection. In addition, the method of detecting the concrete quality of the pile by the core drilling method belongs to the local damage detection method, when the local strength of the pile concrete is too low or the concrete cementation is poor, the cohesion between the mortar and the coarse aggregate is easily destroyed in the core drilling process, which affects the accuracy of the detection results.

The core drilling method of the pile is used to detect the integrity of the pile.

The Technical Regulations for Testing Concrete Strength by Core Drilling Method require that the holes after core sampling should be repaired in time.

Generally, the methods of dealing with air agility are:

1. Using pressure, from the bottom of the core hole to the top with Changhao cement slurry backfilling.

2. If the drilling area accounts for less than 2% of the pile area, it will not affect the bearing capacity of the pile. Because the difference in geological conditions between the piles leads to the difference in bearing capacity is much greater than the difference in the pile area, in addition, there is a 5cm protective layer outside the reinforcement cage, so that the borehole will be at least 10cm away from the reinforcement cage, and this situation can also be left untreated.

1. Coring part:

1) The part of the structure or component that is less stressed;

2) Concrete strength and quality representative parts;

3) The part that is convenient for the placement and operation of the core drilling machine;

4) Avoid the position of the main reinforcement, embedded parts and pipelines, and try to avoid other reinforcements;

5) When the strength is comprehensively measured by the core drilling method and the non-damage method, the same side area should be taken with the non-damage method.

2. The number of coring shall comply with the following provisions:

1) When testing according to a single component, the number of drill cores of each component should not be less than 3; For smaller components, the number of drill cores can be taken as 2;

2) When testing the local area of the component, the core position and the number of core samples should be proposed by the unit requiring testing;

3) The number of core samples for concrete strength correction by rebound method should not be less than 6.

There are two types of pile core sampling and testing standards:

1. Ultrasonic testing method for pile trouser drill core, ultrasonic and low strain dynamic testing method is a non-damage detection method, which should be carried out one by one for the pile foundation of important projects or important parts.

2. The pile core detection method is a local damage shelter detection method, which should be used in accordance with the specified sampling ratio and when there is any doubt about the quality of the pile, and the integrity of the pile can be judged by the core detection method, the integrity of the pile, the strength of the concrete, the length of the pile, the ballast at the bottom of the pile and the characteristics of the bearing layer can meet the requirements of the design and specifications.

Key points of the position of pile foundation coring:

1. The section of the component with insufficient safety cannot be cored for the part with large stress; The joints of the components and the edges of the components, the stress of the concrete is complex, and it is not suitable for coring, and the components with the same conditions are suitable for coring in the middle of the components, and the coring is generally selected on the foundation, wall and column, and the coring is not done on the beam as much as possible.

2. With the help of magnetic inductors, avoid the steel bars of the structure, especially the main reinforcement, and avoid the embedded parts or pipelines.

3. Select the parts with representative concrete strength and quality.

4. When used for non-damage method correction, it should be in the non-damage test area or close to the non-damage test area.

The role of pile foundation coring detection and coring requirements.

The core sample taken out should be numbered in order from top to bottom, and should not be reversed, lost, replaced, and the hole number, the number of returns, the depth of the return, the total number of blocks, and the number of blocks should be written on the core sample, and all the core samples should be photographed in time before the sampling test. The coring process and the core sample taken out should be supervised, inspected and accepted by the supervising engineer, and the core sample should also be properly preserved. <>

Pro, hello Bored pile coring is a method for quality inspection of bored piles, which is stipulated as follows:1Coring Depth:

The coring depth is generally required to be more than 1 3 of the drilling depth, but not less than 2 meters. 2.Coring location:

The coring position should be on the drilling axis, and the distance from the orifice should not be less than 1 meter. 3.Coring method:

The coring should be perpendicular to the drilling axis, the coring tool should be kept clean, complete and sharp, and excessive vibration and shock should be avoided during the coring process, so as not to affect the quality of the coring. 4.Coring Quantity:

The number of coring should be determined according to the actual situation, and the pure high opening generally requires at least 2 core samples for each borehole. 5.Core Identification:

The core sample taken out should be identified, including the orifice number, coring depth, sampling date and other information, so as to facilitate subsequent quality inspection and analysis. It should be noted that when carrying out the coring of bored piles, the relevant regulations and operation procedures should be strictly adhered to to ensure the safety, stability and reliability of the quality of coring and bored piles.

The provisions for the coring of bored piles are as follows:1At least 1 core sample should be taken for each bored pile, the drilling depth should exceed the pouring depth, the length of the core slag cherry sample should not be less than the sampling depth plus 1 core sample should be taken in the borehole within every 4 holes for inspection, and the proportion of 1 core sample for every 4 boreholes should be sampled and inspected in more than 4 boreholes.

3.The core sample of bored pile should be sent to the inspection agency for testing, and the test results should meet the requirements of the specification. 4.

If the strength of the core sample in an inspection batch does not meet the requirements of the specification beam formwork, all bored piles in the batch are considered unqualified and need to be reconstructed or repaired. It should be noted that the above regulations are only coring regulations under general circumstances. The specific coring regulations and inspection standards may vary according to different regions, project types, cast-in-place pile diameters and other factors, and it is recommended that construction and inspection be carried out in accordance with relevant specifications and standards in specific projects.

The core pulling test of pile foundation boring is suitable for testing concrete cast-in-place piles (the pile diameter is generally not less than and the pile quality of the underground diaphragm wall (such as the concrete cementation condition of the pile body, whether there are porosity, segregation, looseness, broken pile, mud inclusion, honeycomb, dog hole, etc.), concrete compressive strength, sediment thickness, contact relationship between concrete and bearing layer and rock (soil) properties of the bearing layer at the bottom of the pile, etc.

The quality evaluation of piles should be carried out according to a single pile. When one of the following situations occurs, it should be judged that the inspected pile does not meet the design requirements:

l. Pile integrity category is W type pile;

2. The representative value of the compressive strength of the core sample sample of the inspected pile concrete is less than that of the pile with the design strength grade on the concrete

3. The pile length and the thickness of the sediment at the bottom of the pile do not meet the requirements of the design or specification

4. Piles whose properties (strength) or thickness do not meet the requirements of the design or specification on the bearing layer rock at the end of the pile.

5. When the core hole deviates from the pile, only the core sample part of the drill is evaluated.