How to do the construction quality inspection of cement soil mixing pile?

Cement-soil mixing pile.

Construction quality inspection.

The quality inspection before the excavation of the foundation pit should be carried out before the roof of the retaining wall is poured, and the test content includes the review of the pile strength and the number of piles. The pile strength test should be carried out by making cement soil test blocks or drilling coring methods. The test block is made using cubes.

Mold test, each mechanical shift spot check 2 piles, each pile should not be less than 2 sampling points, should be within 1m above the bottom of the pit and above the bottom of the pit soft soil layer in the pile sampling. Make 3 cement soil test blocks at each sampling point. And it should be cured underwater and measured at the age of 28 days without confinement compressive strength.

The number of bored coring samples is not less than the total number of piles and not less than 3, each with 3 points and 3 test blocks per point. The strength of the test block obtained by drilling coring should be multiplied by the coefficient, and the coring pores should be closed by grouting in time after the completion of drilling and coring.

Quality inspection standard for biaxial mixing piles and cement-soil mixing piles.

The construction quality inspection of cement-soil mixing pile is mainly tested according to the design and construction specifications in the following aspects according to the frequency: first, the light dynamic penetration test is done 7 days after the pile is completed, the strength of the pile body is detected, and the number of contact strikes is 35 times, and the results should be corrected according to the age of each pile; the second is to do the unconfined compressive strength test after 28 days, and select the test sample from the core pull; the third is to do the core core testing of the pile quality after 28, and randomly select the stirred piles for testing according to the frequency specified in the specification; Fourth, according to the design requirements, the bearing capacity of a single pile or a composite foundation is tested.

In addition, it is necessary to carry out an on-site inspection of the pile quality of the pile head.

Summary. 1. Before construction, the quality of cement and external admixtures, pile position, mixer working performance and the integrity of various metering equipment (mainly cement slurry flowmeter and other metering devices) should be checked.

1. Before the construction of the celebration book, the quality of the cement and the external admixture, the pile position, the poor working ability of the mixer and the integrity of various metering equipment (mainly cement slurry flowmeter and other metering devices) should be checked.

2. During the construction, the lifting speed of the machine head, the amount of cement slurry or cement injection, the length and elevation of the mixing pile should be checked.

3. After the construction is completed, the pile strength, pile diameter and foundation bearing capacity should be checked.

4. When carrying out the strength test, the specimen after 90d should be taken for the load-bearing cement-soil mixing pile; The specimen should be taken after 28 days for the supporting cement-soil mixing pile.

5. The quality inspection standards for cement-soil mixing pile foundation should comply with the regulations.

Before construction, the following tests need to be done:

1. Cement inspection. According to the design requirements, select the cement to send to the testing center.

2. Soil sampling. Try to use the most unfavorable soil sample in the pile depth range and send it to the testing center, and they will use the ring knife method to make a soil density to prepare for determining the amount of cement.

3. Make cement-soil mixture. According to the design water-cement ratio (there is also a dry mix, there should be no water-cement ratio requirements), pile diameter, 28-day compressive strength and other design indicators, please test the center to do the cement soil mix ratio.

4. After construction, the testing center will go to the site for coring, do an unconfined compressive test, and also do a bearing capacity test, which is qualified if it meets the requirements.

Definition of cement-soil mixing pile is a method used to strengthen the saturated soft clay soil foundation, which uses cement as a curing agent, through a special mixing machinery, the soft soil and the curing agent are forcibly stirred in the depth of the foundation, and a series of physical and chemical reactions between the curing agent and the soft soil are used to make the soft soil hard into a high-quality foundation with integrity, water stability and certain strength.

The reinforcement depth is usually more than 5m, the dry reinforcement depth is not more than 15m, and the wet reinforcement depth is not more than 20m. The cement slurry pressed into the soft soil is forcibly mixed with the surrounding soft soil with the rotating mixing blades to form mud solidification.

At the beginning, various raw materials such as cement and admixtures should be sent for inspection, and then on-site sampling should be used to determine the mixing ratio of cement slurry, and then the quality inspection of each formed mixing pile focuses on the amount of cement, the number of tanks mixed with cement slurry, whether there is slurry breaking in the grouting process, the time of spraying and stirring and the number of re-mixing. In order to ensure that the amount of mixing per meter of the pile and the amount of cement slurry meet the design requirements, each machine should be equipped with a computer recorder. At the same time, the site should be equipped with a cement slurry specific gravity tester in case the supervision engineer and the quality inspector of the project management department can spot check and check whether the cement slurry water-cement ratio meets the design requirements at any time.

Quality inspection: 1 Light penetration method 7 days after the pile is completed, the light exploration method can be used to inspect the quality of the pile. Use the spoon drill with the light cone probe, drill and sample in the center of the pile, observe whether the color is consistent, check the uniformity of small soil stirring, check whether the strength of the pile can meet the design requirements according to the relationship between the number of light contact blows and the strength of the cement soil, and the depth of the light and portable exploration method is generally not more than 4m.

2 core sampling method cement production process into piles completed, after 90 days of vertical bearing cement soil, transversely bearing cement soil after 28 days, with the method of core sampling to check the integrity of the pile, the degree of uniformity of stirring, the strength of the pile, the verticality of the pile. The drill core sampling frequency is 1%. The diameter of the cement mixing pile is generally 500mm 550mm, and the maximum is 600mm, and the strength of the common grade of curing agent is.

In addition to 7% 12% of the quality of the wet soil that can be reinforced in block, the rest should be 12% 20%.

Reinforcement depth: 20m for wet <, 15m for dry <

Summary. Hello dear.

Hello, it is generally necessary to do "cement mixing pile detection"; If it is an engineering pile, the bearing capacity must be tested; If it is a maintenance pile, it is necessary to take a core sample to test its cement content.

What kind of test and detection need to be done after the construction of cement mixing pile is completed.

Hello, dear Huai, you know that you generally want to do "cement mixing pile detection"; If it is an engineering pile, it is necessary to detect the bearing lead tremor and dissipation; If it is a maintenance pile next to the hole, it is necessary to take a core sample to test its cement.

Is there anything else I can do for you?

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Quality inspection during construction.

1. Pile position: the deviation is not more than 5cm.

2. The elevation of the top of the pile and the bottom of the pile: should not be lower than the design value, the bottom of the pile should generally be 10-20cm deep, and the top of the pile should be 10-50cm high.

3. The verticality of the pile should not exceed 1%.

4. Pile cement quality: the amount of cement for each pile is allowed to be adjusted within the range of 25kg.

5. Cement marking: selected according to the design requirements.

6. The speed of lifting the spraying slurry (or powder spraying) on the mixing head: the lifting speed does not exceed.

7. Selection of external admixtures: usually calcium chloride, sodium carbonate, triethanolamine, calcium lignosulfonate, sodium silicate, etc.

8. Slurry water-cement ratio:

9. Uniformity of cement slurry stirring.

10. Uniformity of powder spraying and stirring.

11. When the powder is sprayed to 1-2m from the ground, there is no phenomenon of a large amount of powder flying and polluting the environment.

12. For the lateral enclosure pile in the foundation pit excavation project, the adjacent pile body requires lap construction, and the adjacent pile construction should be continuous, and the construction interval time should not exceed 8-10 hours.

Quality inspection after the completion of the project.

1. Standard penetration test and dynamic penetration test.

2. Cone penetration test.

3. Coring inspection.

4. Static load test of pile foundation.

Quality inspection after foundation pit excavation.

1. Water leakage on the wall.

2. The verticality and uniformity of the pile wall.

3. The number of cracks in the pile body and the degree of development, the lack of piles and broken piles.

4. Pile strength and uniformity.

5. The development of cracks in the pile body and the roof beam of the pavement and the degree of detachment.

6. Horizontal displacement of the pile top.

7. The leakage at the bottom of the pit is agitated.

8. The uplift of the bottom of the pit.

Reference standards and specifications.

1. Code for Acceptance of Construction Quality of Building Foundation Engineering GB 50202-2002

2. Building construction manual.

3. Technical Specification for Ground Treatment JGJ 79-2002