Construction scheme of super high-rise bored pile?

the construction scheme of super-high-rise bored pile is very important. The scheme is made by professionals through on-the-spot investigation and rational use of professional knowledge, and every detail is crucial. Zhongda Consulting will tell you about the construction scheme of super high-rise bored pile.

1. General situation:

The bored pile is used in the project of Building No. of p>XX Garden, and the designed pile diameter is φ8. The enclosure is in the form of bored cast-in-place piles with a pile diameter of φ85. The concrete grade is C3, and the underwater grade is improved to C35.

The basic quantities are as follows: the engineering piles are φ8mm, with an effective length of 5.1m. The pile ends enter ⑦2b gray-yellow silt layer, and the absolute elevation of the pile ends is-54.15m. There are ***499 piles, of which 15 piles are also used as supporting lattice columns. The retaining row piles are φ85mm, the effective length is 17 meters, the absolute elevation of pile end is -16.25m, and there are 259 piles.

2. Construction process flow

Note: The lattice column can only support the column piles

3. Hard ground construction process

1. Overview

According to the distribution of engineering piles and the sequence of pile construction, combined with the technology of bored pile, a certain amount of vertical and horizontal connected ditch network and a certain capacity of mud pool with circulation, sedimentation and waste storage functions are set up; Hardening the ground with concrete; Harden the ditch and pool with bricks, so that the mud forms a closed circulation system and is discharged in an orderly manner. It solves the problem of mud overflowing and site softening, so as to achieve the unity of comprehensive benefits of bored pile construction quality, safety, progress, economy and civilized construction.

2. Hard floor construction technology

1. Hardening site procedures and technological processes

* Be familiar with the pile map, determine the site elevation, level the site and determine the hard floor elevation.

* Dig and build mud pits and mud ditches according to the site layout.

* drain the temporary pipeline.

* The site concrete is cast 5~1cm, with the label C2.

3. Mud process flow

4. Technical measures for measurement and positioning

According to the plan of pile location, building red line and main foundation axis provided by the owner, the pile location is determined by theodolite orientation and steel rule distance according to the plan location, and each pile location is nailed into the ground with red painted steel bars, with the point deviation less than 5 mm. Then determine the pile position and submit the recheck sheet for the supervisor's recheck and acceptance.

5. technical measures for burying liners

surveyors and engineers and technicians are responsible for the accuracy of burying liners. The diameter of liners is φ Φ95mm, the burial depth is ≯2m, the deviation between the central axis and the center is ≤1mm, and the surrounding areas are backfilled with clay and compacted in layers. The liners are rolled with 3mm steel plates, with a height of 1.2-1.5 m, and the top should be provided with a reinforcing ring. The diameter of the liners should be greater than the pile diameter by 1mm. The liners should be buried deeply, firmly and correctly, and the surrounding soil should be backfilled and compacted in layers. The depth of the bottom of the barrel into the original soil is not less than 2mm. The deviation between the center point of the cylinder and the actual pile site is not more than 1 mm.

6. technical measures for hole-forming construction

1. after the drilling rig is in place, the chassis should be padded flat, and the center of the pile position, the active drill pipe and the crown block should be on the same vertical line.

2. At the beginning of hole-forming drilling, slow drilling should be done with light pressure, and mud should be circulated with a small amount of pump to prevent the deviation of the hole protection barrel caused by severe vibration of the drill bit.

3. To ensure verticality, rigidity and concentricity of drilling tools, the diameter of drill bit must be the same as the designed pile diameter.

4. Use drilling parameters correctly. The stratum lithology in the construction area is mainly cohesive soil and silty soil. When drilling parameters are selected, the WOB of cohesive soil can be controlled at 1-2kPa and the rotating speed is 2-4r/min. The WOB of silty soil and sandy soil can be controlled at 15-25 kPa and the rotating speed is 4-7r/min.

5. Correct use of mud performance index, positive circulation pore-forming is adopted in the construction, and the mud performance index is controlled as follows:

The mud performance index density of the injection orifice is ≤1.15, and the viscosity is 18 ″-2 ″

The mud performance index density of the discharged pore products is ≤1.3, and the viscosity is 2 ″-22 ″

6. Hole cleaning technical measures are carried out in two times

. When cleaning the hole, the drilling tool should be lifted about 2cm away from the bottom of the hole, and 1.25-1.3 high-density mud should be used until there is no slag, and the hole cleaning at one time is over. The second cleaning shall be carried out in the reinforcing cage. After the conduit is placed, the conduit shall be used, and the hole cleaning shall be carried out with low-density mud ≤1.15. To meet the requirements for the end of the second hole cleaning, the mud density shall be controlled ≤1.25, the viscosity ≤ 22 ",and the sediment thickness <; 1mm。

7. Fabrication and installation of reinforcing cage

Prepare the sectional drawing of reinforcing cage according to the design drawing, adopt the bending mould of reinforcing bar, process reinforcing cage according to the design requirements and specifications, and make reinforcing cage in sections, and the length of each section is determined according to the length of incoming materials. The blanking should be accurate, the main reinforcement should be straight, and the surface should be free of dirt and corrosion.

a special bench and construction platform are provided to make the reinforcing cage, so as to ensure that the cage body is straight. The annular stirrup and the main reinforcement are connected by spot welding, and the spiral stirrup and the main reinforcement are connected by spot welding at intervals.

The processed reinforcing cage should be carefully checked and accepted according to the specifications and design requirements, and the unqualified part should be corrected, and it can only be lowered into the hole after it is qualified.

The stacking and handling of reinforcing cages should be kept straight to prevent bending and deformation.

when the reinforcing cage is lowered into the hole, it should be placed vertically, aiming at the hole position and slowly and gently, so as to avoid colliding with the hole wall. If there is an obstacle in the cage, it is not allowed to be forcibly lowered. The reason should be found out and the lowering should be continued after appropriate treatment.

During wellhead welding, the surface dirt on the welding parts of the main reinforcement should be removed, and the positions of the main reinforcement of the upper and lower cages should be set straight, and the upper and lower cages should be in a vertical state, and the two sides should be welded symmetrically. After welding, the stirrups at the welding parts should be supplemented, and the next cage can be installed only after acceptance.

the installation depth of the reinforcing cage should meet the design requirements. after all the holes are confirmed to meet the requirements, the reinforcing cage should be fixed so as to position the reinforcing cage and avoid going down and arching when pouring concrete.

the welding electrodes used for reinforcing bars shall have the factory inspection sheet and warranty, and the raw materials and welding tests shall be carried out according to the requirements of the regulations.

The main reinforcement of segmented reinforcing cage adopts single-sided welding lap, and the length of lap seam is 1d, and the number of joints of main reinforcement in the same section is not more than 5%.

the solder joint is firm, and the weld width and stack height should meet the specification requirements.

in order to ensure the thickness of the protective layer, a group of protective blocks should be set every 4m in the longitudinal direction of the steel cage, and 4 blocks in each group are symmetrically distributed.

The reinforcing cage should be installed in the center of the hole position, hung straight and steady, and slowly sink to avoid collision with the hole wall.

after all the reinforcing cages are inserted into the holes, the reinforcing cages will be sent to the predetermined elevation with positioning steel bars in time, and they will be hoisted and fixed. The false control of cage top is controlled within 1 mm.

8. technical measures for installation of perfusion catheter

the catheter is a tube with a wall thickness of 3mm, a diameter of 258mm and a length of 2.5m m.

the conduit shall not be bent or sunken, and the joint shall be sealed with sealing ring to block water.

the depth of the catheter into the hole should be controlled at about 5cm from the bottom of the hole.

9. Technical measures for underwater concrete pouring

Underwater concrete pouring shall be carried out within 3 minutes after secondary hole cleaning.

select high-quality commercial concrete according to the design and owner's requirements. The initial setting time should be considered when preparing concrete, and the pouring time should be shortened as much as possible.

the slump of the concrete used in the construction shall be tested according to the quality standards required by the regulations, and the slump of the poured concrete shall be 18~22cm. At the same time, during the grouting process of each pile, one group (3 blocks) of test blocks shall be made as required, and the samples of test blocks shall be representative, maintained according to the requirements of specifications, and sent for inspection 28 days later.

in this project, the design strength grade of pile concrete is C3, and the construction adopts commercial concrete. The actual strength grade of concrete should be improved by one grade, namely C35 (or underwater 3). In order to ensure smooth concrete pouring. Commercial concrete adopts fluid concrete, and the slump is controlled at 18~22cm.

during the initial pouring of underwater concrete, the iron wire for installing the waterproof bolt in the conduit should be cut off only after the initial pouring of sufficient concrete. The waterproof plug adopts ball bladder.

underwater concrete pouring should be carried out continuously, and the conduit should be buried under the concrete surface from beginning to end. It is forbidden to lift the conduit out of the concrete surface, and the depth of the conduit buried in the concrete should be 3-1m, at least not less than 2m. The catheter shall be removed frequently in Ying Qin, and the tube removal shall not exceed 6m at a time.

attention should be paid to controlling the pouring speed of concrete, especially when the concrete surface rises to the bottom of the reinforcing cage, the pouring speed should be slowed down, and the lifting conduit should be stable to avoid the reinforcing cage floating (floating cage) caused by excessive discharging impact or the coupling hook of the conduit with the reinforcing cage.

in the process of pouring, there must be someone who is responsible for measuring the height of the concrete surface, and lift and dismantle the conduit in time. The buried depth of the conduit is 3~1m, and it is forbidden to lift the conduit away from the concrete surface. The initial pouring amount should ensure that the buried depth is not less than 2m.

in the process of concrete pouring, the rising surface height of concrete should be determined frequently according to the flooding situation. The reserved height of concrete column above the top surface of pile shall be controlled at 2-2.5m..

concrete pouring shall be continuous and compact without interruption. At the same time, in the process of pouring, Ying Qin moves the conduit in series, which makes the concrete filling dense.

in order to ensure the quality of the pile head, a certain amount of over-grouting should be carried out above the design elevation according to the design requirements. Its perfusion filling coefficient shall not be less than 1.5.

after the concrete pouring is finished, cut the steel hanger in time, pull out the casing, and remove the orifice mud and residual concrete slurry.

1. main construction equipment

specifications, models, unit quantities

engineering drilling rig GPS-15 sets, 55*3KW

pouring platform platform 55*22KW

mud pump 3PNL set, 11*22KW

deep mixing pile driver SBJ-II set, 43 * 75kw

. Summary of construction scheme of 24KW

super high-rise bored pile: According to the distribution of engineering piles and the sequence of pile construction, combined with the technology of bored pile, Set a certain amount of vertical and horizontal connected ditch network and a certain capacity with circulation and sedimentation

more information. Real estate E-net

air compressor 3WC-O.9/7A, 44*5.5KW

crane QY12-16, 2

sewage truck 8t, 6

sewage pump NL65A-16, 22*. 5.5KW

theodolite J6, 2

level S3, 1

grout guide pipe Ф 258m 25

11. Construction quality control standard

1. Pile length reaches the design length, pile diameter (+5mm,-mm)

2. The thickness of sediment before grouting after hole formation is not more than 1mm.

3. The strength, quality and bearing capacity of pile body meet the design requirements.

4. The filling coefficient of pile concrete should not be less than 1 and should not be greater than 1.3.

5. The compressive strength and mathematical statistics evaluation indexes of concrete blocks should meet the design and specification requirements.

6. The deviation between the actual pile position and the designed pile position is less than 1mm.

7. Vertical deviation of pile hole <; 1/1。

8. allowable deviation of reinforcing cage fabrication: main reinforcement spacing is 1mm, stirrup spacing is ±2mm, reinforcing cage diameter is 1mm, and reinforcing cage overall length is ±1mm.

12. Quality assurance measures for bored pile construction

In order to ensure the smooth progress of this project under the premise of ensuring quality and time limit, the following specific rules-based quality assurance measures must be formulated and implemented in a strict quality management system:

1) Control of raw materials for construction

All raw materials for construction must be purchased from qualified suppliers screened and confirmed by the company. The main material acceptance requirements are as follows:

(1) Acceptance of steel: the grade, variety and diameter of steel (reinforcement) should meet the design requirements. All steel products (steel bars) must have quality certificates. And sampling mechanical retest shall be carried out according to each batch of no more than 6 tons. You can only use it if you pass the second interview. At the same time, the spot-check test of spot welding of reinforcement cage is also carried out according to the sampling standard of every 3 pieces under the welding conditions of the same welder and the same specification.

⑵. Acceptance of commercial concrete: Commercial concrete must be provided by the concrete supplier who has been audited by the municipal building materials industry management office and issued the Certificate for the Application of Commercial Concrete. When the commercial concrete is supplied to the site, the quality certificate of the commercial concrete shall be obtained from the concrete supplier according to the quantity within the same batch during site acceptance. Two tasks should be done well in the acceptance of construction site. One is the detection of slump, and the unqualified concrete should be returned. Secondly, the concrete test block made on site is taken as the final evaluation basis of the concrete strength of this bored pile unit project. No less than one set of test blocks shall be made for each pile. Considering the influence of initial setting on the pile quality, the time interval between the commercial concrete delivered to the site and its delivery from the mixing station and its use by pouring shall not be more than 2 hours.

2) control of construction personnel

(1). All managers and construction personnel engaged in quality-related work must use personnel who have been trained in special functions and skills and passed the examination. On-the-job personnel in important positions such as project manager, builder, quality engineer, safety officer, material engineer, rig operator, welder and steam crane operator must hold relevant certificates.

⑵. Before starting work, educate all construction personnel and management personnel engaged in quality, organize a quality activity summary appraisal meeting once a week or every ten days, put forward rectification opinions and formulate rectification measures for outstanding problems.

(3). The quality responsibility system should be institutionalized. The quality responsibility system should not only be implemented in specific heads and operation teams, but also reflect the clear scale of rewards and punishments. The quality responsibility system must be posted on the wall to facilitate mutual supervision.

3) Construction process control

The construction process control of bored pile is mainly embodied in four concealed engineering projects: "hole forming", "hole cleaning", "fabrication and installation of reinforcing cage" and "concrete pouring".

The key points of control are as follows:

(1) Hole-forming:

The parameters of hole-forming drilling and the performance index of mud used must be determined according to the trial hole-forming results. In order to make the parameter selection representative, the number of trial holes should not be less than 2, and the diameter of the hole-forming bit must be the same size as the pile diameter. Pay attention to regularly check the wear degree of the drill bit and repair the size in time according to the wear condition.

the verticality control of hole formation should generally be controlled by the stable positioning of the drilling rig and the vertical positioning of the frame. This stability and perpendicularity must be determined by the trial run of the drilling rig and the correction of the special level. It is forbidden to use the method of visual gross estimation.

the hole-forming construction shall be completed continuously at one time, and drilling shall not be stopped without reason. In the flow operation of drilling holes, the safe distance between adjacent holes should not be less than 4 times the distance between piles, and the minimum time interval should not be less than 36 hours.

⑵. hole cleaning:

hole cleaning must be done twice or more, and the principle of hole cleaning termination conditions should be mastered: after the first hole cleaning, the feel of mud should be basically free of particles and slag. After the second hole cleaning, the mud in the hole should be basically new slurry after replacement, and the mud density, viscosity, sand content and sediment thickness meet the design and specification requirements.

(3). Fabrication and installation of reinforcing cage

The fabrication dimension deviation of reinforcing cage should be strictly implemented in accordance with the specifications, and eye-catching reinforcing cage fabrication standard cards should be hung in the on-site processing shed as a reminder.

in order to prevent the irretrievable distortion of the reinforcing cage caused by careless handling and lifting, the reinforcing cage should be moved and lifted under the condition of multi-point average stress.

On-site reinforcement cage yard should be flat, and the pile height should not exceed 2 floors.

The installation cage body of the reinforcing cage should be upright, and it should be smooth and free from obstruction when sinking into the hole for 3 times. The segmented reinforcing cage should be welded firmly to prevent the cage from escaping.

the elevation data of the depth positioning under the reinforcing cage should be checked and approved by more than two people, and the standard is supervised and confirmed by the hole.

(4). concrete pouring

concrete pouring should be carried out within 3 minutes after the second cleaning, otherwise it should be decided whether it is necessary to clean the hole again according to the sediment thickness measured again. The commercial concrete used should have good