(1) Preparation before construction
A, site leveling, remove sundry, backfill soil should be compacted;
B, dredging a mud pond, a sedimentation pond and a water storage pond to prepare qualified clay;
C, water and electricity are connected;
D, when burying the liners, the periphery of the liners should be tamped, with the top 30cm above the ground and the bottom buried 2.0-2.5m. The liners should be upright from top to bottom, and the plane deviation of the centerline of the liners should be less than 5cm.
E, the frame should be straight, the machine should be smooth, not uneven hardness, not displacement and uneven settlement when drilling.
F, mud index: the sand content of clay layer 16 "- 17 "sand layer 17 "- 19" shall not exceed 8%, the colloid content shall be above 90%, and the specific gravity is about1.2-/.
G. The mud tank shall be dug to a height of 20cm, a width of 30cm, a length of not less than 15m, and a mud flow rate of not more than 10cm/s ".
H, when installing the drilling rig, it is required that the center of the turntable and the lifting pulley on the drilling rig are on the same axis, and the position deviation of the drill pipe is not more than 20cm. "
(2) Drilling
A, drilling tool connection should be vertical, the initial drilling speed should not be too fast, and the hole depth should not exceed 2m/h within 4.0m and 3m/h in the future. In the overburden, the WOB should always be reduced, and the ROP should be adapted to the mud displacement.
B, in the process of drilling, often test the change of mud index, and pay attention to adjust the mud height in the borehole.
C, often check whether the machine is running normally, and report it immediately if it is abnormal. The parts that need lubrication must be checked once per shift.
D, wrenches, hammers, crowbars and other gadgets are fastened with safety ropes to prevent them from falling into the holes.
E, always pay attention to observe whether there is any crack on the ground near the hole or whether the casing and drilling rig are inclined.
F, strictly abide by the operating procedures, pay attention to every small link, and make detailed records.
G, after the final hole cleaning, use the original mud method to clean the hole. After hole cleaning, the mud index specific gravity is1.15-1.258, the sand content is less than 4%, the viscosity is17 "-20", the hole bottom should not be more than 5CM, and the hole depth should meet the requirements of design and construction specifications.
H, hole cleaning should be checked and confirmed by the supervision engineer, and the visa is hidden.
1. During hole cleaning, keep the water level in the hole higher than the underground water level 1.5-2.0m to prevent hole collapse.
(3) Reinforcing cage system.
A, reinforced approach must have a certificate of approval, each batch of materials, each specification must be sampling inspection qualified rear can use.
B, reinforcing cage made of main reinforcement joints should be staggered, the joint within the same section shall not exceed 50%.
C, steel binding process should strictly abide by the specification.
D precast concrete blocks shall be installed on the outside of the reinforcing cage to ensure the protective layer of reinforcement.
E, reinforced know to prevent deformation in hoisting, reinforced cage into the hole after positioning is firm, must prevent reinforced cage is pulled up when lifting catheter.
F, appropriate welding steel hoop and steel hanger, to ensure that the reinforcing cage is not deformed during installation.
(4) Concrete pouring
A, pouring underwater concrete with a conduit with a diameter of 25cm, and the length of each conduit is >; 4m, the catheter should be assembled before use, and the leak test should be done (0.3 MPa), which is suitable for 15 minutes without water leakage.
B. When installing the conduit, the base end should be 30-40 cm higher than the bottom of the hole, the depth of the conduit buried in concrete should be 2-3 m, the deepest should not exceed 4m, and the shallowest should not be less than1m. An attached vibrator should be set at the upper end of the conduit to make the hoisting speed of the conduit slow.
C, concrete slump is 18-22 cm, to prevent pipe plugging.
D, concrete continuous pouring interruption time shall not exceed 30 minutes, and the top height of cast-in-place pile shall be 0.5- 1.0m higher than the design.
E, in the process of construction, should keep the site clean and sanitary, mud shall not overflow, sediment should be removed in time.
F, after the completion of the construction, chisel out the pre-heightening concrete at the pile head, and measure or core it.
1, bored pile construction.
(1) Preparation before construction
A, site leveling, remove sundry, backfill soil should be compacted.
B, establish a closed traverse network, and close it with the municipal advanced control points to achieve the accuracy required by the specification. After acceptance, the traverse points will be used as the benchmark for pile location lofting. Traverse points should also be closed to meet the accuracy requirements. When the casing is buried, the pile position will be destroyed, so after the pile position is determined, put more than two protection piles. Check the accuracy of casing with protective piles. Ensure that the deviation of pile position meets the requirements. Total station is used for measuring and setting out, and the data is calculated in polar coordinates. Pile spacing can be measured with steel ruler.
C. Dig mud pools, sedimentation tanks and storage tanks, and prepare qualified clay or bentonite.
D, connect the water and power supply.
E. bury the liner. The periphery of the pile casing should be compacted, with the top 30cm higher than the ground, the buried depth at the bottom 1.5-2.0m, the diameter of the pile casing is 20cm greater than the pile diameter, and it stands upright from top to bottom, with the deviation of the center line of the pile casing less than 5cm. Generally, steel lining is adopted, and the thickness of steel plate is 0.8- 1.0 cm. Casing should be buried manually or mechanically, and find out underground obstacles.
F, remove underground obstacles. There may still be some pipe network occupying the pile site, so it is necessary to find out the underground pipe network before the bored pile construction and take measures to remove the underground obstacles on the pile site as soon as possible.
G, pile frame in place. The frame should be straight, the base should be stable and the hardness should not be uneven. Generally, the pile driver should pad sleepers. During the drilling process, the frame will not shift and sink unevenly.
H, mud index. Clay layer 16 "- 17 ",sand layer 17 "- 19", sand content less than 8%, resin ratio greater than 90%, and specific gravity about1.2-1. Mud quality directly affects drilling progress.
I the mud tank shall be 20cm high, 30cm wide, with a length of not less than 15m and a mud flow rate of not more than10cm/s. ..
J, drilling machinery adopts rotary drilling rig. The design requirement is 2m at the bottom of into the pit. .
(2) Drilling
A, drilling tool connection should be firm and vertical, the initial drilling speed should not be too fast, and the hole depth should be within 4.0m, not more than 2m/h, and not more than 3m/h in the future. Always drill holes in the overburden under reduced pressure, and the drilling speed should be suitable for mud discharge. When drilling, the percussion drill should be slow, and the hole depth should be less than 2.0m and not more than1.5m/h. ..
B, in the process of drilling, often test the change of mud index, and pay attention to adjust the mud concentration in the borehole. The buried depth of underground water level in this project is 2-3 meters, and the mud pressure exceeds the water pressure, which can meet the requirements of construction specifications.
C, often check the operation of machines and tools, find out the reason immediately if any abnormal situation is found, and handle it in time. Wire rope and lubricating parts must be inspected once per shift.
D, wrenches, hammers, crowbars and other gadgets are fastened with safety ropes to prevent them from falling into the holes.
E, often pay attention to observe whether there are cracks on the ground near the borehole or whether the pile casing and pile frame are inclined.
F, strictly abide by the operating technical regulations, and make drilling records. Mud changes should be reflected in the records.
G, when the drilling reaches the design depth, the supervision engineer shall, jointly with the relevant personnel of the construction unit, judge and accurately determine the hole depth at the scene. As the basis of the final hole elevation.
(3) hole cleaning
A, drilling to the design depth, the construction unit put forward the final hole-forming requirements, which need to be decided by the on-site supervision engineer, and acceptance of the aperture, hole inclination and hole depth. The acceptance method is to make a reinforcing cage with a length equal to 4-6 times of the pile diameter and a diameter equal to the aperture, hang the reinforcing cage into the hole, and smoothly put it into the bottom of the hole required by the design, indicating that the aperture and skewness meet the requirements. Measure the hole depth with measuring rope and steel ruler. When the reinforcing cage cannot be lowered to the bottom, it needs to be repaired until the hole wall is straight and the reinforcing cage can be lowered to the bottom smoothly.
B, hole cleaning method is to clean the hole by replacing the original mud. After hole cleaning, the mud index specific gravity is between 1. 15- 1.20, the sand content is less than 4%, the viscosity is 20-22 ",and the sediment at the bottom of the hole is less than 5cm. In order to prevent the mud and sand in the hole from exceeding the specification requirements, the mud and sand in the hole are generally knocked off first, and then the slurry is changed with a noise pump.
C, hole cleaning should keep the mud level in the hole higher than the underground water level 1.5-2.0m to prevent hole collapse.
D, hole cleaning meets the requirements, and the supervision engineer will check the hole depth, mud and sediment thickness again. Upon the visa of the supervision engineer, it is agreed to pour concrete concealed before the next working procedure.
(4) Installation of reinforcing cage
A, reinforced approach must have a certificate of approval, each batch of materials, each specification must be sampling inspection qualified rear can use.
B, reinforcing cage production must be carried out in strict accordance with the design drawings and specifications. General reinforcement cage welding, individual connection points pierced holes. The positioning steel bars on the outside of the reinforcing cage can be prefabricated with hollow porous concrete cylinders, or directly bent and welded on the main reinforcement with steel bars to ensure the thickness of the protective layer of the main reinforcement.
C, reinforcing hoop of reinforcing cage must be welded with main reinforcement, and covered electrode generally adopts 5-prefix model to ensure the welding quality of reinforcing cage. The reinforcing cage cannot be deformed during installation.
D, reinforcing cage is best to use the crane once.
E, steel hanger should be welded at the top of the reinforcing cage, higher than the steel casing. After the reinforcement cage is in place, the hanging reinforcement is supported on the sleeper at the top of the pile casing, and cannot be directly placed on the pile casing.
F, ultrasonic testing pile reinforcement cage installed galvanized steel pipe and connected with stirrups, to ensure that the testing steel pipe is watertight.
(5) pouring underwater concrete
A, with a diameter of 20cm catheter pouring underwater concrete. Each catheter is 3-4 meters long. Before using the catheter, try to assemble it first, and do a water-closing test (0.3Mpa), and it is advisable that it does not leak for 15 minutes. Carefully check the weld of the catheter.
B, the bottom of the catheter installation should be higher than the bottom of the hole 30-40 cm. The depth of the conduit buried in concrete is 2-3m, with the deepest not exceeding 4m and the shallowest not less than1m.. The lifting speed of the conduit should be slow.
C, the number of concrete nozzle should meet the requirements of the pipeline buried in concrete depth, and the corresponding number should be prepared in front of the nozzle.
D, concrete slump is 18-22 cm, in case of pipe plugging.
E, concrete should be poured continuously, and the interruption time should not exceed 30 minutes. The elevation of the top of the cast-in-place pile should be higher than the design elevation by more than 0.5m. The concrete is made of commercial concrete or self-provided mixing equipment, and the concrete is put into the tank by bucket or pumped directly.
F, in the process of construction, should keep the site clean and sanitary, mud shall not overflow everywhere, mud residue should be removed in time.
(6) Pile foundation detection
A, chisel in addition to the pile top pre-heightening concrete, pile head reinforcement can't bend. Chisel the pile head with a pneumatic pick or a hand chisel. The elevation of pile top should meet the design requirements, and the pile top should be roughly flat.
B, pile foundation detection methods are dynamic detection and ultrasonic detection. The detection method of each pile is determined by the design and supervision engineer and the quality inspection department.
C, the construction unit should cooperate with the quality inspection department to test each pile. Only after the quality is qualified can the construction of the next working procedure be carried out.
Construction technology of manual digging pile
1. Excavation sequence: When the distance between adjacent piles is less than 2 times the diameter of the pile body, boundary piles should be constructed first, and before the excavation of the post-construction piles, the pre-construction piles should have been poured with concrete and meet the strength requirements. After the concrete pouring of pile core is completed and the core-pulling inspection is qualified, the superstructure construction will be carried out.
Second, the digging pile construction technology
The construction procedure is as follows: site leveling → setting out → determining pile position → erecting bracket or electric foundation reed → preparing submersible pump, blower and lighting equipment. → Pumping while digging → Cleaning the surrounding wall of the pile hole every 90 mm, checking the diameter and verticality of the pile hole → Supporting the breast wall formwork → Pouring the breast wall concrete → Dismantling the formwork to continue digging. After the breeze reaches a certain depth, the survey unit will accept → tie the reinforcing cage → accept the reinforcing cage → remove the accumulated water at the bottom of the hole and put it into the string tube, and the core concrete of the cast-in-place pile will reach the design top elevation.
Third, the site treatment
1. Level the original site.
2. Set drainage ditches at proper positions around the building to make collecting wells, as shown in 5.3.
3. Make a concrete cushion on the excavation surface, and the concrete thickness of C 10 is100 mm. ..
Four, pile hole earthwork treatment
Temporary earthwork stacking area shall be set up on the construction site, and the excavated earthwork shall be transported away by car within two days (excavator shall cooperate with manual loading), and the excavated earthwork shall not be stacked on the edge of the hole to ensure the smooth flow of the construction site. In the first construction stage, the earthwork of construction sections ③ and ⑥ is transported to construction section ④ by derrick. (2) During the construction period, the earthwork is transported from the temporary ramp to the construction period (4), piled up in a unified way, and then transported to the garbage dump by dump trucks.
Verb (abbreviation of verb) mining
1. Before excavation, make disclosure of underground soil layer and underground distribution to each operation group. The possible problems and general treatment methods are pointed out.
2, each pile hole has a fixed team responsible for the construction, each underground and under construction must be operated by someone, the safety responsibility of underground operators should be clear, and there is a good contact signal from top to bottom.
3. Keep enough fresh air in the well and continuously supply gas to the well.
4. When transporting waste soil and other building materials vertically in the well, measures should be taken to ensure the safety of underground workers, and a safety zone should be set at the bottom of the well to prevent objects from falling and hurting people.
5. The excavation work must be carried out continuously, so as to shorten the connection time as far as possible, reduce the exposure time of unsupported soil in air or water, and prevent collapse.
6, when the adjacent hole pile is pouring concrete, in principle, to stop piling, in case the shaft under greater soil lateral pressure and instability collapse.
Six, reinforcing cage adopts the method of on-site processing, well binding, and then hoisted into the bottom of the well. Steel bar connection adopts double-sided lap welding, and the lap length is ≥5d. See 5.4.
Seven, dig a hole in concrete engineering
Digging pile concrete is divided into two parts: retaining wall concrete and pile core concrete.
1, concrete retaining wall project
(1): The retaining wall of this project is a wedge-shaped ring with the upper part and the lower part, which is rammed into the shaft in sections during excavation. In a relatively stable soil layer, the height of the front section of the retaining wall is 900 mm. When the pile passes through the strongly permeable layer, the height of each section should be about 500 mm In case of water content and quicksand, straw can be inserted into the steel bar to prevent the mud and sand from flowing out. When the situation is serious, you can use it.
(2): Retaining wall concrete is dense and early-strength, with slump of 3-5CM, and 1CM fine stone is used. It is forbidden to vibrate with an internal vibrator, so as not to affect the stability of soil outside the formwork. Longitudinal steel bars are embedded between the upper and lower retaining walls to make them a whole, and the joints of each section are guaranteed to be watertight.
2, pile core concrete engineering
When the soil quality of the excavated pile meets the design requirements, the residue at the bottom of the hole shall be removed, and the design, survey, quality inspection and construction units shall jointly organize the acceptance of the pile hole. After the design requirements are met, the next working procedure shall be carried out, and the steel bar shall be bound and the pile core concrete shall be poured.
3. Preparation before pouring pile core concrete
(1) Eliminate plugging and water accumulation. Before pouring concrete, the leakage on the concrete retaining wall should be blocked in time, and then the water in the well should be discharged to ensure the quality of the pile core concrete. By plugging, a large area is blocked into a small area, a small area is blocked into a point leak, and finally blocked.
⑵ Preparation of chute, chute and cylinder: The concrete reaches the pouring surface through the cylinder, and its free-falling height should not be greater than 2M, otherwise it will cause the concrete to be layered and uneven, which will affect the concrete quality.
4. Pile core concrete construction
(1), pile core concrete shall be vibrated, and dense concrete shall be compacted by underground operators in layers with plug-in vibrators. The thickness of the first layer shall not exceed 50CM, and the insertion form shall be vertical. The spacing between insertion points is about 40-50CM, so as to achieve "fast insertion and slow extraction".
[2] The core concrete of each pile must be poured continuously at one time without leaving any construction joints, and the continuous gap shall not exceed 2 hours.
(3) Pay attention to control the pouring height of the pile core concrete, so as not to cause the pile core concrete pouring to be too high (but it must be about 3CM higher than the designed pile top elevation, and the laitance on the pile top should be chiseled before the upper structure concrete construction). If there is too much laitance at the top of the pile, the mud must be washed out and poured with concrete with small slump, preferably without laitance.
(4), each pile core concrete do a set of specimens, and ensure that each workbench class not less than a group.