2, project overview
2.1. design overview
Xinyu. Emerald City 2 3A # building. 97 hand-dug piles, placed on the pile side pile diameter 900,1000,1200,1300 required design weathered sandstone and shale strata for no more than 1D less. With C30 concrete pile material, reinforcing steel using HPB235, HRB335; pile longitudinal reinforcement joints welded joints; protective layer, thick 50mm. pile of two security levels.
2.2. engineering geology
According to the investigation report, engineering geology distribution: site terrain is flat, the first layer of soil miscellaneous fill strength is low, high water content, which should not be used as a base layer of the class; the 2nd layer of silty clay layer, the soil is uniformly granular structure, interspersed with a large number of iron, manganese, dry high-strength, toughness, the bottom of the strong weathering of sandstone and a small amount of debris containing mudstone ; layer 3 sandy shale, gray, bedding development, a large number of gravel pieces, with a small number of cracks, with a large mass of iron and manganese, interbedded mudstone interspersed, chondrites, the more crushed amount.
3. construction preparation
1, familiar with the construction drawings and soil, groundwater hydrogeological data.
2, according to the current project into a pile of artificial pile hole wall support in accordance with the soil in the region, the distribution of groundwater soil moisture characteristics of the pumping station excavation to provide geological survey and geological information on the wall supporting the calculation and design. Ground leveling seedlings, trees and other obstacles need to be dealt with before
3, excavation site.
4, fully excavated before selectively digging two holes for pile testing, analysis of soil, hydrology and other relevant information in order to the original code of the construction program
5, the groundwater level of the area is relatively high, lower the groundwater level to about 0.5 meters below the first end of the pile column.
6, safety-critical operations manual digging, excavation before the construction staff to carry out a comprehensive safety and technical briefing; safety before spreader inspection and test of operational reliability to ensure construction safety.
7, materials and major equipment:
7.1.1 Cement: No. 325 to No. 425 ordinary silicate cement or slag silicate cement should be used.
7.1.2 Sand: sand or coarse sand with mud content not exceeding 5%.
7.1.3 Stones: 0.53.2 centimeters gravel or crushed stone grain size; piles of concrete can also be used without diameter in the stone and clay content does not exceed 2%.
7.1.4 Water: The application does not contain harmful substances in tap water or purified water.
7.1.5 Addition of early-strengthening agent should be selected by test, fly according to the provisions of the laboratory to determine the gray mix.
7.1.6 Reinforcing steel: horizontal reinforcement diameter must meet the design requirements, factory re-examination certificate and report.
7.1.7 General should ride Miki, group or electric hoist winch, wheelbarrows or dump trucks, picks, shovels,
hand shovels, welding, wire fall, fixed pulley guided pulley block, concrete mixers, buckets, tanks, pipes, vibrators, plug welding, thick rope, wire rope, safety activities covered, waterproof lamps (low-voltage 36V, 100W),
welding machine. Ventilation and oxygen supply equipment, head pumps, wooden windlasses, movable ladders, helmets, safety harnesses, etc.
7.1.8 template: combined steel, bent steel 4 warele (or eight) assembly. Clamps, hoists
hooks and spare parts. Timber, wood, 8 or 12 channels, etc..
3.2. construction schedule
Started on November 09, 2010 and completed on December 8, 2010, with the testing requirements of the pile.
3.3.
According to the requirements of labor organization and general engineering construction progress, the arrangement of manual labor digging holes 30, two pairs, industrial facilities, technicians of the captain; steel processing and tying personnel 5, concrete 3. The project manager to arrange a professional, high-quality workforce 1.
4. construction flow chart of the main construction methods
4.1. technical measures manually dug piles
Construction of manually dug piles points as the process: wall concrete ratio, hole plate attic, center position and hole depth measurement of each part. Requirements for each part of the construction soil, water seepage, center deviation, the beginning of the depth of the timely record of construction.
1, before excavating the site to clean up debris, leveling and tamping, accurate sampling, piling around the hole in the center of the distance of one meter to set up four piles of protection, cross-symmetrical arrangement. At the end of the construction of the wellhead wall, will be marked in the center pile wellhead wall.
2, a row of rows of pile foundation excavation, the use of spaced digging holes, excavation, group piles, plum blossom-shaped excavation should be used to avoid the impact of adjacent piles retaining wall excavation. When encountering a slight flow of sand, the Great Wall shortens the length of 0.5 meters, reducing the exposure time of the excavation hole wall, timely wall pouring concrete.
3, digging holes, the use of lenses even with the wall concrete, concrete wall labeling should not be less than C25. wall template should be used in the shape of a trumpet to unite the two semicircular steel, wall thickness of 12-20CM, centralized mixing, pounding columns, the wall hole diameter after the wall, according to the design of each part according to the design of the pile design pile diameter of the pile diameter of the wall than the aperture to open the 16 cm large. When the wall is not dense concrete vibrator, wall leakage occurs, we should deal with it in time. When small leakage, waterproof material can be blocked directly. Slightly larger holes in the water surface, you can enter the wedge, waterproofing materials, and then closed around. Huge water pressure, seepage-proof large hole, according to the size of the hole, choose the appropriate plastic pipe embedded in the diversion, closed around the waterproofing material, pile in the excavation hole, with a drainpipe leading out of the water out of the hole, in the grouting of the pile in the concrete in front of the eyes, Department of wire and cut pipe.
4, in each section of the excavation, pile hole recovery center, sampling of the part with a hammer hanging hole center position to prevent the heart of a pile deviation. High with a shovel shovel, hard soil and strong weathered rock with a pickaxe crushing digging clay layer.
5, when digging holes within 10m, use a blower to ventilate the hole, keep the air fresh. Filling in the air solidified
Soil, usually in the string pipe material, layered or short vibrator casing construction method of direct feeding. Practice has proved that the combination of two ways to better ensure the dense construction of pile concrete. Because of groundwater in order to minimize the impact, it is necessary to speed up the filling speed to complete the concrete in a short period of time to pour a sufficient amount of the required concentration, the use of the concrete's own weight to inhibit the infiltration of groundwater.
6, large underground concrete uniformity, the impact of density. What kind of concrete construction method should be determined according to the groundwater flow rate. From the bottom of the hole, and when a large hole wall rising groundwater infiltration rate (reference value ≧ 6mm/min), the method should be used underwater piles, carry out engineering specifications set out in the terms and conditions of the details. However, it should be noted that before the concrete borehole water level filling must be at least 11.5 meters for the same height or higher than the water outside the table.
7, vertical lifting equipment set up a company should be able to withstand a certain momentum will not be disrupted, vertical lifting equipment must be put into use after check. Digging the pile design bottom elevation, using a test probe hole vertical hole with the depth of the hole. The project is proposed to invest mainly in latitude and longitude instrumentation automatic leveling level and so on.
8, when the pile hole depth is greater than 20M, underground ventilation should strengthen air convection. Oxygen is delivered when necessary to prevent the hazards of toxic gases. When operating up and down on the pile hole personnel operator's rotating closely monitor the situation, observe the pile personnel react to each other, and effectively prevent accidents. If not in the local water, cut and transported out of the bucket of mud. Underground engineering seepage water is large, the bucket has been unable to meet the drainage, digging pool hole pile at the bottom of the water pump pumping the elevation of the submerged, while the precipitation side of the excavator, pumping specifications pumping fixed. Should be three shifts day and night pumping, the water level remains stable.
9, when the groundwater level is high, measures should be taken to coordinate the precipitation, and then excavation.
10, pile installation activities through the horizontal orifice safety cover when someone posted digging holes, they should include a good safety cover to prevent debris from falling on people. Irrelevant personnel shall not be close to the edge of the pile orifice. When lifting soil, then open the safety cover. Part of the pile lifting earth excavation (pruning), starting from the second quarter, the use of lifting equipment earth, pile holes should wear a helmet, ground personnel should be hauled with harness. When leaving the top of the bucket mouth 1.5 meters, actively pushing the safety cover, housing openings, to prevent dumping dirt soil, rocks and other debris fall down the hole injury. Push the car in a small bucket after the dump, and then open the lid of the activity, the power to decentralize the bucket loading soil. Pile hole dug to the required depth, with the hole in the diameter of the pillar and vertical check the pile wall circularity, up and down should be leveled, trimming the hole wall.
4.2.
The four levels are proposed around the building construction survey and design, and this is the basis of building settlement observation. The level of four-point closure difference should be less than ±12√H. Site preparation and earth excavation should protect the good level of the points.
Before excavation should be based on the auxiliary control point field, set up a single axis control point, and this for the foundation axis control and release. Measurement and control lines of latitude and longitude of the axis, each pile position of the heart of the steel tape for the axis, and review the pile, the pile is set in the vertical center of the position of each control axis around the four stakes, review write a report to the commissioner, after signing the confirmation of the Great Wall
Started the first mold construction, concrete retaining wall above the natural ground should be the first mold construction of 150 millimeters. After the wall, and each axis elevated lead control to the upper mouth of the wall with bamboo nails or piles standard center axis, boiled marked with red paint, easy to control and pile elevation of the center.
4.3. manually dug hole piles into the hole construction
4.3.1.
Pile construction construction crews before each day of attention should be arranged to go down the shaft wall has been done to check the situation, in the absence of abnormal samples to enter the hole under the mold excavation.
4.3.2. artificial pile hole construction
1.
Earth excavation construction process (or pumping) → clear the hole wall, check the verticality and pile diameter → → → digging down the concrete retaining wall.
2. Hole construction method
①. When using a short pickaxe, shovel and manual excavation and other simple tools, encountered relatively hard rock, available for picking or
Contoured artificial construction. Vertical soil, soil and artificial vertical movement; axis of the first review and correction after the start of excavation, each concrete wall 1 meter shot once like, that is, one meter construction section; when the pile hole with a depth of more than 10 meters fan, lost fresh air conduit piled up into the hole, put the soil down the barrel or cage to ensure smooth contact.
②. For excavation in a group of two each group of two to three days to arrange a bunch of assembly line to ensure that each pile per day or to build five teams of two pipe cores across the construction of footage across the construction of a hole.
3. In the excavation of rocks or other obstacles encountered, the use of manual labor and air compressor, and pick with the construction.
④. In the process of making holes, send people to repair the ground through the water channel, pumping water from the well in time to drain the hole pile in the water to dig the hole pile waste soil or stone ballast is transmitted by the person responsible for the timely appearance of other than.
⑤. Pile, longitudinal diameter check: control points and points for the foundation of the standard should be located in the axis of the pile does not affect the construction of the place. Before the start, after the review should be properly protected, construction should be frequently retested. Into the wall hole by the first quarter of the field technicians in the wall after setting bamboo piles around the axis centerline orthogonal to the pile crosshairs control, for reducing the construction and pile verticality deviation control for the basis of the template, check the diameter of the rod with a ruler to find ways to carry out the circumference.
3. Quality inspection checkpoint
Earth excavation, concrete wall secondary behavior, must be found at each inspection, deviation, corrected at any time to ensure the precise location.
4.3.3. wall construction
A large pile like wall wall
Large sample description: the use of C20 fine gravel concrete
Concrete wall > 1. wall construction
Pile holes are dug to the required depth, and the diameter of the hole's strut and the vertical check the pile wall circularity, the top and bottom should be leveled, trimming the hole wall. First remove the first section of the wall template, put extra reinforcement, wall template, in order to use the turnover use of savings demolition of the next section. Part of the wall poured concrete, concrete bucket string sent, manually poured, manually inserted and pounded dense. Specific can be determined by experiment to mix the early-strength agent to accelerate the hardening of concrete, such as narrowing the aperture should be adjusted with a small piece of the template. The upper mouth of the template to leave 100mm of concrete pouring port interface height should be pounded dense. After demolding
Concrete blocks or bricks rigorously, smooth cement mortar, for 1MPa demolding strength. Use concrete pile diameter per pile diameter, pile diameter of the caliber of the next plus 500mm, height 1100mm or 2500mm wall construction. Part of the wall should be greater than 30 in the ground 50cm to keep or points, etc..
4.3.4.
Checking the design of the digging hole class after the last hole, the construction unit should be self-tested assessment to check the content of the pile in the last hole including the pile hole centerline displacement deviation, the pile diameter deviation, the depth of the final hole, the bottom of the hole sediment and the environment compelled by the pile substrate, and the deviation should be within the scope of the design and specifications are allowed. Reporting supervision, investigation, verification and design institute and the owner and other departments and for hidden acceptance visa procedures.
When continue to expand the construction before verifying the relevant departments in charge of the strata design after the expansion of the construction unit should be a good start after the construction of self-inspection and evaluation, reported to the supervision, survey, design units and other owners of the department for hidden acceptance visa verification procedures.
4.3.5. digging injection
1. vertical pile hole and diameter, should be checked at each time, found deviation, timely correction to ensure the correct position. According to the construction design requirements
2. Pile end final hole depth, after each pile, in the last hole must be required to survey, design, owner, competent inspection and acceptance, to carry out secret inspection of the root cause.
3. If the hole collapses, landslides occur outside the brick mold, with the appropriate amount of spacing rebar diameter 150mm 6MM, and then support the mold pouring concrete retaining wall.
4, when groundwater or rainwater infiltration rapid inflow, pumping and drainage is not timely, there will be water. Excavation process digging hole bottom pool, pump pumping water in time. If a small amount of water, pouring concrete can be used semi-rigid in the first disk, a large amount of water in the case, and remove the difficult moment, pouring underwater concrete conduit method applied to ensure construction quality.
5 bottom of the hole residual virtual earth up. ;Into the hole, and pruning soil, broken bricks, accidentally removed are relatively empty. Put the bottom of the hole around the reinforcing cage should be carefully checked to remove debris virtual earth. When necessary, the back cover with cement mortar or concrete.
6 Vertical deviation is too large: due to the excavation process is not in accordance with the requirements of the verification of each section of the vertical, resulting in later digging a vertical super deviation. After each digging section, hanging straight axis must be based on the pile open, trimming, so that the hole straight up and down the wall to maintain the arc.
7. Wooden piles must be dug or scaffolding boards, wire mesh cover to prevent clods, debris, personnel fall. Strictly prohibit the use of straw bags, plastic sheeting false cover.
4.3.6. quality standard
1 Pile hole centerline displacement tolerance: ≤ 30 mm; .
2 Tolerance of pile hole diameter: negative deviation is not allowed;
3 Tolerance of concrete wall thickness: ±15 mm;
4 Thickness of slag at the bottom of the hole: not allowed.
4.3. manually dug hole pile reinforcing cage
Making and installing the security of reinforcing cage welding system is adopted, making the hole or multiple holes to form two tie molding construction process, as appropriate, choose to use.
4.3.1. Reinforcing steel cage production
1 material requirements:
Steel mills must have enrollment and quality assurance certificate, the method should be based on the specification of the reinforcement, type, batch piling respectively, according to the witnessing sampling and testing requirements, please supervisory units, *** with the witnessing site notification of the sampling, submitted to the approval and supervision of the unit of the written test scores of the technical director of the construction unit can be dealt with behind the scenes to identify the production of qualified The steel piling inspection on the site listed in the location requirements, clearly labeled has been checked, qualified, unqualified words.
2. Before the rebar cage should produce a different kind of pile dug out by the real root, according to the actual sample production using flash butt welding or arc welding, in the process of operation on the ground, every stiffening hoops, spiral bar 300 connectors is a batch of acceptance sampling and inspection before use. When the production figures, after listing, by stacking the root opening.
4.3.2. tying reinforcement cage construction method
1 construction should have before the conditions:
①, pile into a hole about acceptance, acceptance procedures have been handled by the last hole.
②, steel products and raw materials and inspection report certificate.
③, the hole water has been drained of fresh air ventilation equipment and air through the test after passing the hole downward conveyance.
④, and then to the team's work before the safety and technical tests. .
2 process: enhance the material on the well → → → reinforced hoop hoop weld residual height and reinforcement → → → binding screws hole hanging rebar cage for concealed installation procedures → → → pile concrete pouring
installation.
3.
According to the design requirements and production of reinforcing steel cage actual pile length, reinforcing component holes when the next lap reinforcing material to ensure that lap joints 500 meters 35D or the number of ranges do not exceed the said reinforcing hoops produced by the reinforcement of 50% should be to ensure the protection of the pile reinforcing layer of not less than 50mm, the length of the helical coil section can be tied 3-5 to meet the required length of the reinforcement laps; not less than More than three hoops pile tip level.
4.3.3. erected in the molding of the hole after the steel cage
Steel cage production methods to ensure the safety of lifting the cage, decided to use a comprehensive method of derrick lifting or to carry out the lifting of a pile of steel cage installation.
1. Located in the upper part of the cage stiffening hoop reinforcement welded together as a hanging point for hanging piles.
2 when carrying out the part of the reinforcing cage, using a one-time overall lifting method pile reinforcing cage installation; when carrying out the segmented reinforcing cage, put down a section of the reinforcing cage hanging in the mouth of the upper part of about 1.0 meters then the last section of the reinforcing cage lifting, so that the alignment welded reinforcement, and then around the helix, the entire reinforcing cage slowly lifting into the instead of the hole.
3.
Reinforcing steel cage reinforcing cage hidden check after installation, should be its elevation, steel diameter, spacing, spacing, welding quality, tying quality, protective layer self-test, a written report, supervision engineers to check the self-test qualified, inspection and approval, in a timely manner for the hidden project signature procedures.
4.3.4. Tolerance of steel cage production
1 Spacing of reinforcement bars: ±10mm;
2 Spacing or spacing of helical bars: ±20mm
3 Diameter of cage: ±10mm;
4 Length of cage: ±50mm;
4.4.1. 425# ordinary silica is suitable or slag cement, factory certificate and inspection certificate. Cement, factory certificate and inspection report: requirements
1 cement material. .
2 sand: sand with mud content not more than 3%. .
3 Stone: crushed stone, diameter 10-15MM, mud content not more than 2%.
4.4.2. concrete supply
Adopted on-site centralized supply, transportation with tanker trucks, pouring dumping concrete mixing station.
4.4.3.
As the pile concrete pouring concrete pouring pile hole seepage is different, according to the actual situation to choose different pouring methods.
1. Concrete is poured to the top of the pile, and the pile should be appropriately above the design elevation to ensure that the elevation of the top of the pile meets the design requirements after removal of the floating slurry. The top of the steel pin on the pile must be maintained at the design size and inserted vertically with sufficient protection layer. When the pile hole is basically free of water, the use of pouring concrete, concrete pumping concrete delivery when necessary conventional methods.
2. seepage holes faster, but also quickly depleted anti-seepage pile hole with a simple conduit structure. A bunch of excavation work on the platform, take a high - 6M steel able to support more than 1 - 2 tons of heavy work simple frame; by way of filling conduit and funnel (holding a small funnel 0.2 m3 of concrete, holding the ball) underwater concrete; conduit is inserted into the pile hole of the chain hanging on the bottom of a simple frame work; concrete pouring preparations, pumping wells with submersible pumps; should be able to get only 10cm or so of the hole
Depth to make the submersible pump, should be immediately to the funnel and pipe pumping concrete; can be filled with concrete on the surface of the funnel, the chain guided conduit exit conduit inside the rise 2cm, so quickly fill the hole at the bottom inside the concrete pipe
and rise to surround the conduit, continue to pour the concrete when the concrete is no longer flowing towards the hole until when the conduit surface, the concrete is no longer flowing towards the hole, so as to increase the continuous pouring of concrete in the hole, the concrete should be poured into the hole, and the concrete will be poured into the hole. To raise the concrete continuously filling the bottom of the hopper. Continue pouring according to this method. Cycle in accordance with the method, when there is a certain height (near the top of the chain), remove the top part of the conduit; With the gradual removal of the conduit to rise the surface of the concrete; When you arrive at the top of the pile above the design elevation of 10 to 20 centimeters, that is, discharging the surface water, the use of inserted vibrator vibration of the surface of the concrete to remove the surface of the floating slurry. This method pile head shorter stay, in the concrete slump should be controlled at about 16-18 cm.
3. When a large number of seepage (> 6mm/min) construction difficulties and pumping should be used drilled pile construction method underwater concrete pouring. Concrete pile pile from the bottom to the pile elevation above once. In case of power outage and other special reasons, construction joints must be left, can be inserted into the reinforced concrete short amount of the surrounding surface. Before infusion of new concrete, the surface must be clean of seams, chiseled, free of water and isolation materials.
4. Pile concrete, concrete surface must be used from the pipe trough, within 2m of the string, not allowed to throw shovels in the wellhead or reverse tilt material to avoid concrete segregation, the impact on the overall strength of the concrete.
5. Concrete filling process, pay attention to prevent groundwater into the water layer not more than 50mm thick, otherwise, you should try to use the conduit concrete surface water layer filling concrete before drying. If the seepage is too much (> 1M3 / H), the program should be underwater concrete construction.
Pouring concrete side side taps, using a vibrator vibration mode to ensure that the concrete is dense.
6, when the concrete pile body, digging the hole in the adjacent 10M working range should be stopped, and shall not let people at the bottom of the hole.
7, when the concrete pile body, will be retained test blocks, not less than one group (3) per pile, timely test report.
According to the design requirements, the use of dynamic testing methods to detect the two piles pile quality testing, test reports should be submitted to the design unit for review.
8. After the pile concrete pouring is completed, the pile and pile top elevation should be checked. Pile reinforcement or the top of the stick to help positively save the life, prevent shrinkage of concrete, dry.
4.4.4. Pile testing, the use of dynamic testing methods pile foundation quality testing, each pile is subjected to testing, the test report should be submitted to the design unit for review.
5, technical measures to ensure the quality
To ensure the quality of the project has developed the following quality assurance measures:
1, careful study of the drawings, drawings to do the design intent to divert the work and to achieve a comprehensive understanding of the need for process changes; do level testing, for better preparation, strictly in accordance with the construction procedures for construction of the construction work.
2, strict compliance with national standards and technical rules in the section of construction quality inspection and engineering assessment standards, sub-project quality assessment, assessment by the national quality inspection engineering standards assessment.
3, the inspection team set up unit operation of the project manager and the team leading the department composed of regular or irregular inspection.
4, gearshift operation team self-test and various types of systems and processes between the acceptance of tracking full-time quality inspector inspection monthly quality inspection company, check out the quality problems in a timely manner with the development of effective prevention and implementation of corrective specific measures.
5, all raw materials, semi-finished products must have factory certificates of conformity or quality assurance and inspection reports, such as copies must be stamped by the original unit seal and pointed out the original. Input related materials, materials, employees use sampling before passing, to fill out the "raw material inspection notice" sent to the laboratory, after the laboratory.
6, by the project manager of the measurement unit project is responsible for good positioning measurements, axis, elevation, vertical monitoring and settlement, etc., on the control points and standard points of the axis must be in a solid selection and reliable components and protection. Release positioning quality inspector and audit acceptance technical director in time to enter the next process of construction and positioning of the release bacteria release bacteria before reviewing the record and find the record.
7, on the axis, elevation, construction layout, reinforcing materials and individual pieces of raw material application and processing and other technical review, subject to engineering and quality inspector, responsible for auditing, delivery before construction.
8, do a good job of checking the hidden works for self-assessment, self-testing, self-checking based on 24 hours in advance will be "notice of acceptance of hidden works" before entering the next acceptance of the road construction process after delivery to the site supervision engineer.
9, the use of field-mixed concrete core piles, the amount of concrete needed for each batch, the person responsible for the site. Each site pouring concrete, must be based on the weather, site conditions, a method to determine the actual concrete pouring of structural elements; strictly in accordance with the specifications required to do specimen sampling, sampling should be dense concrete vibrator, do not allow the phenomenon of honeycomb, there must also be a person responsible for the regular maintenance of the concrete, to ensure the quality of concrete.
10, construction management and special types of construction personnel must be licensed, strictly prohibited without a business license.
11, for the higher authorities and supervisors to put forward quality problems or hidden dangers