What are the specific quality requirements of manually dug cast in place piles?

GB50202 has detailed regulations.

The allowable deviation of the stakeout position is as follows:

Group pile 20mm;

Single row pile 10mm.

The pile acceptance of the pile foundation project, in addition to the provisions of the design, shall be carried out according to the following requirements:

1. When the design elevation of the pile top is the same as the elevation of the construction site, or after the construction of the pile foundation, it is possible to inspect the pile position, and the acceptance of the pile foundation project should be carried out after the construction is completed.

2. When the design elevation of the pile top is lower than the elevation of the construction site, and the pile position cannot be inspected after the pile is sent, the driving pile can be carried out in the middle when the top of each pile sinks to the site elevation, and the final acceptance is carried out after the construction of all piles is completed, and the cushion cap or bottom plate is excavated to the design elevation. The cast-in-place pile can be intermediate acceptance of the position of the casing.

The pile position deviation of the cast-in-place pile must meet the provisions of the table, the elevation of the pile top should be at least higher than the design elevation, and the quality of the pile bottom hole cleaning according to different pile-forming processes has different requirements, and should be implemented according to the requirements of each section of this chapter. There must be 1 group of specimens for every 50m3 poured, and 1 group of specimens for piles less than 50m3.

The allowable deviation of the plane position and verticality of the cast-in-place pile (**) [see 50202 specification for detailed data].

Engineering piles should be tested for bearing capacity. For the cast-in-place piles with a foundation design grade of Grade A or complex geological conditions and low reliability of pile quality, the static load test method should be used for inspection, and the number of inspected piles should not be less than 1% of the total number and should not be less than 3, and when the total number of piles is less than 50, it should not be less than 2.

The quality of the pile should be inspected. For cast-in-place piles with a design grade of Grade A or complex geological conditions and low reliability of inspection quality, the number of sampling inspections should not be less than 30% of the total number and should not be less than 20; The number of sampling inspections of other pile foundation projects should not be less than 20% of the total number and should not be less than 10; For precast concrete piles and cast-in-place piles above the groundwater level and verified after the final hole, the number of inspections shall not be less than 10% of the total number of piles, and shall not be less than 10. There shall be no less than 1 under the cap of each column.

The quality, inspection items, batch and inspection methods of raw materials such as sand, gravel, steel, cement and other raw materials shall comply with the provisions of the current national standards.

Except for Section 1 of this CodeIn addition to the main control project of the provisions, other main control projects should be all inspected, for general projects, in addition to the specified provisions, others can be spot-checked according to 20%, but the concrete cast-in-place pile should be fully inspected.

1. Drilling and perfusion.

Bored pile refers to the pile hole formed in the foundation soil by means of mechanical drilling, steel pipe squeezing or manual excavation at the engineering site, and placing a reinforcement cage and pouring concrete in it to make a pile.

2. Immersed tube perfusion.

It refers to the pile formed by using the hammer piling method or vibrating piling method, sinking the steel casing with a flap pile tip or prefabricated reinforced concrete pile shoe into the soil, and then pouring concrete (or putting a steel cage in the pipe first), and pulling the pipe while hammering or vibrating. The former is called the hammer rock skillfully immersed tube cast-in-place pile, and the latter is called the vibrating immersed tube cast-in-place pile.

3. Manual digging holes.

Refers to the pile hole is formed by manual excavation method, and then the reinforcement cage is placed, and the pile made of concrete is poured. In order to ensure the safety of the manual digging pile construction in the over-coarse cherry key path, it is necessary to consider the prevention of hole wall collapse and quicksand during construction, and formulate reasonable wall protection measures.

The bearing capacity of the manually dug pile is slightly larger, and the reasons are: The punched cast-in-place pile is generally constructed with mud wall protection, and the lateral resistance of the pile is not suitable for exerting itself compared with the manual dug pile. The sediment at the bottom of the hole of the punched pile is definitely not clean, and it is easy to exceed the specification or design requirements, while the manual digging pile is cleaner, so that the bearing capacity of the bottom of the Li pile can be more exerted.

Artificial digging piles are mostly suitable for gravel, rock and soil and other foundations with low water levels, and can be worked in the column pit by workers, and the relative piles are not very deep. Bored piles are mostly used for sandy, silty soil and other foundations with high water levels, which are made into holes by the drilling machine, and go through the processes of hole cleaning and wall protection, and the depth of the relative pile is deeper.

Pile foundations include: hammered immersed pipe cast-in-place piles, hydrostatic immersed pipe cast-in-place piles, punching piles, manually dug piles, prefabricated piles, PHC pipe piles, root piles, frank and coarse late anchor piles, etc., which are different because of their construction methods and construction bench simplicity and quality control standards. If the punching pile is considered to be drilling, the difference lies in the construction technology and quality implementation standards.

Answers]: a, b, c, d

Textbook, pp. p71-76

The characteristics of manual digging and cast-in-place piles are that the construction machinery and equipment are simple, the operators are not simple and simple, there is no vibration, no noise, no environmental pollution during the operation, and the impact on the surrounding buildings is small; The construction speed is fast and the cost is low.

1. Quality control of hole formation.

1. Pile position positioning quality control, according to the construction unit's measurement datum point and measurement baseline lofting positioning, after supervision and review, with the cross legal hole pile center.

2. Verticality quality control, and the bottom expansion section should be dug into a round table shape according to the design to ensure the size.

The author believes that in the process of implementing "intelligence", it is necessary to listen to the opinions of management departments at all levels in advance and study what management functions "intelligence" should achieve, which is the core of formulating the plan; Secondly, we should listen to the opinions of professionals, and on the basis of giving full play to the functions of hardware equipment, we should pay attention to the management methods, what data can be provided by the equipment and programs for the management work, and what supplements and improvements ...... the specific management workThe purpose is clear, and it is necessary to avoid "taking the will of the chief" and "taking things for granted".

3. The quality control of the hole pile wall protection is the use of concrete wall protection, generally the height of each section is 60cm, the thickness is 15cm, and the concrete grade is consistent with the pile. Brick wall protection is adopted, and the net distance is not less than the design pile diameter.

Second, pile quality control:

1. Hole cleaning quality control: the hole wall and the bottom of the hole must be cleaned, there is no scum at the bottom of the hole, there is no loosening of the hole wall, and a pump pit should be set up for drainage if there is groundwater.

2. Quality control of steel cage system:

1) steel bar entry to acceptance, to have a quality policy, and required mechanical properties test and welding test, conditional supervision unit should be done parallel test, qualified before it can be used.

2) The welding rod should have a quality insurance policy, and the model should be suitable for the performance of the steel bar.

3) The production of the reinforcement cage is strictly processed according to the design, and the position of the main reinforcement is controlled by the reinforcement and the positioning bracket of the hole forest to control the equal distance.

4) The protective layer of the reinforcement is made of cement mortar blocks, each group, 3 in each group, 120 ° apart in circumference, and the plum blossom arrangement is arranged between each group.

5) Insist on feeding according to the mix ratio, and when the slump loss is greater than 5cm h, the ratio should be adjusted.

6) quality control of concrete mixture, the mixing time of each plate of concrete shall not be less than 90 seconds, a slump test must be done when starting to stir, adjust the fluidity, and have good cohesion, the observation of slump loss when pouring to guide the adjustment of the concrete mix ratio, the mixed concrete should be used immediately, and it is strictly forbidden to pour into the pile hole if there is a segregation phenomenon.

7) Concrete pouring quality control: the distance between the concrete conduit and the bottom of the hole is not greater; The concrete slump should not be too large, with 5-8cm as the finch mu, every 50cm for a layer of timely vibration, concrete perfusion to maintain continuity.

3. Pile quality inspection

1. The strength and quality inspection of the concrete test block and the dynamic inspection of the pile body must be qualified.

Fourth, supervision and control:

1. Supervise the parallel test of important projects as required.

2. In the process of concrete pouring, it is necessary to implement a side station, full staff, the whole process control, and strict control.

3. It is necessary to track the inspection in a timely manner and determine the quality results.

Answer]: a, b, c, e

The characteristics of artificially dug Wublind tung cast-in-place piles are: 1) the bearing capacity of a single pile is high, the structural stress is clear, and the settlement cavity is small;

2) The diameter, verticality and bearing layer of the pile can be directly checked, and the pile quality is reliable;

3) The construction machinery and equipment are simple, the process operation is simple, and the space occupied is small;

4) There is no vibration, no noise, no environmental pollution in the construction, and no impact on the surrounding buildings.

Teach God Agitation p183-200

Answers]: a, b, d, e

p55-58

Manually excavated cast-in-place piles are made by manually digging soil into holes and pouring concrete into piles. The bearing capacity of the single pile of the excavated cast-in-place pile is high, the structural stress is obviously not correct, and the settlement is small; The construction machinery and equipment are simple, the process operation is simple, and the space is small; There is no vibration, no noise, no environmental pollution in the construction, and the aging has no impact on the surrounding buildings.