Construction technology of manual digging pile in building.

The construction technology of manual digging pile is very important. Understanding the construction technology is the first step of construction, and only by clearly knowing the desired effect can we achieve the best. Zhong Da Consulting will explain the construction technology of manual digging pile for you.

I. Introduction

With the development of national economy, all kinds of civil and industrial buildings are increasingly high-rise, and manual digging piles have been recognized by many design units and construction units for their unique advantages of large bearing capacity. It is indeed a basic form of economic application.

Second, the characteristics of manual digging pile

(1) The construction operation process is simple, and the construction is convenient, and large mechanical equipment is not needed.

(2) The bearing capacity of a single pile is high, which can directly check the overall size and bearing layer of the pile, with reliable mechanical properties and strong seismic capacity.

(3) Multiple piles can be carried out at the same time, so that the construction speed is faster, the equipment investment is saved, and the project cost is reduced.

(4) The underground working conditions are poor, the environment is harsh, and the labor intensity is high, so safety and quality are particularly important.

Third, the scope of application

Manual digging pile is suitable for clay and silty clay with a pile diameter of more than 800㎜, clay with no or little groundwater and a small amount of sand, sandy pebbles and loess, especially for loess layer, with a depth of about10m, and can be used for high-rise buildings and public buildings. For quicksand, alluvial areas with high groundwater level and large water inflow, as well as silt and silt with high water content deposited in modern times,

Fourth, the process flow

5. Operation process.

(1), setting out, determining pile position and elevation: according to the data of building survey control network and pile position layout, determine the pile position grid control network and elevation datum point, determine the pile position center, take the pile position center as the center of the circle, draw a circle with the radius of pile body plus the thickness of retaining wall as the radius, and sprinkle lime line as the pile hole to excavate dimension line. Excavation can only be carried out after the pile position line is determined and accepted by the supervisor.

(2) Earthwork excavation of the first pile hole: the excavation of the pile hole shall be carried out layer by layer from top to bottom. Excavate the earthwork in the middle part first, and then expand it to the periphery, which can effectively control the cross-sectional size of the pile hole. The excavation height of each section should be determined according to the soil quality and design, and generally it should be 0.9-1.2m. ..

(3) Supporting wall formwork and placing additional steel bars: In order to prevent the pile hole wall from collapsing and ensure the safe construction of hole formation, a wall protection including plain concrete and reinforced concrete should be set. Cast-in-place reinforced concrete retaining wall is the best, which can be closely combined with soil wall and has good integrity and stability. The thickness of retaining wall and the strength of concrete must meet the design requirements. The formwork for retaining wall can be detached to support the lower section for reuse, and can also be connected with fixtures and fasteners. The steel ring made of channel steel or angle steel is used as the internal support, and the formwork is pressed to prevent the formwork from tensile deformation. There is no horizontal support for easy operation. The retaining wall in the first section should be higher than the ground150-200mm, and the thickness of the retaining wall is higher than that of the retaining wall below100-150mm, which is convenient for retaining soil and water.

(4) Pouring the first section of retaining wall concrete: After the retaining wall formwork is supported, immediately pour the retaining wall concrete, manually pour it, and manually tamp it. When the concrete strength reaches 65438±0.2 MPa, the formwork can be removed. Retaining wall formwork shall be removed according to climatic conditions. Generally, the mold can be removed after 24 hours.

(5) Check the axis and elevation of the pile position (center): set a cross control net and datum point on the ground, measure the axis and elevation of the pile on the first section of the retaining wall, center each section with a cross line, use a hanging hammer as the center control, use a ruler to find the circumference, and use the datum point to measure the hole depth.

(6) Erection of vertical transport frame: After the first pile hole is drilled, vertical transport frame shall be erected on the pile hole, which shall be stable and firm.

(7) Install lifting equipment, bucket, movable cover plate, water pump, ventilator, etc. When installing lifting equipment, try to make the center of bucket wire rope coincide with the center of pile hole, so as to control the pile position and the center of formwork support intuitively when digging. The pile mouth is provided with a fence. When the depth of the pile hole exceeds 5m, ventilation should be carried out underground to strengthen air convection, and oxygen should be transported when necessary to prevent the harm of toxic gas. Personnel on the pile hole closely observe the personnel under the pile hole and respond to each other. A movable cover plate that can move horizontally is installed at the pile hole. When someone digs in the pile hole, cover the safety cover to prevent debris from falling and hurting people. When lifting the soil, open the safety cover again.

(8) Earthwork excavation in the second section of the pile hole: from the second section, the earth will be transported by lifting equipment, and the personnel in the pile hole should wear safety helmets. When the bucket leaves the hole1.5m above, push the movable safety cover to cover the hole, so as to prevent the discharged clods, stones and other sundries from falling into the hole and injuring people. After the bucket is unloaded, open the movable cover plate, lower the bucket to fill the soil, and dig the pile hole to the specified depth.

(9) Dismantle the retaining wall formwork in the first section and the second section to prevent additional reinforcement: the retaining wall formwork is used in turn by removing the support in the previous section, and a concrete pouring opening with a height of 100㎜ is reserved at the top of the formwork.

(10) Pouring concrete for the second section of retaining wall: the concrete is transported by bucket, manually poured and rammed.

(1 1) Check the axis and elevation of the pile position (center): After the wall protection of each pile hole is completed, the horizontal axis and elevation of the pile position must be determined at the upper mouth of the wall protection, then the crosshair is used for alignment, the hanging hammer is set at the bottom of the well, the vertical flatness of the hole wall is checked with a radius ruler, and then the hole wall is trimmed. Well depth must be measured one by one based on the reference point.

(12) Cycle down layer by layer: Dig the pile hole to the design depth and check the soil quality. The pile bottom should be supported on the bearing layer specified in the design.

(13) Digging and enlarging the bottom: the bottom of the pile can be divided into two situations: enlarging the bottom and not enlarging the bottom. When excavating the belled pile, the cylinder at the belled part should be excavated first, and then the soil should be excavated from top to bottom according to the size and shape of the designed belled position.

(14) inspection and acceptance: after the hole is formed, the diameter of the pile body, the elevation of the bottom of the hole, the center line of the pile position and the verticality of the shaft wall must be reported to the supervisor for acceptance, and the construction records shall be made after passing the inspection.

(15) Hoisting the reinforcing cage: The reinforcing cage shall be manufactured, transported and hoisted according to the design to prevent torsional deformation, and the internal fixing bars shall be welded as required. Before placing the reinforcing cage, the mortar pad should be tied. When hoisting the reinforcing cage, it should be aligned with the hole position, hoisted steadily, and slowly sank to avoid collision with the hole wall. When the reinforcing cage is placed in the design position, it should be fixed immediately.

(16) Concrete for cast-in-place pile: clear the accumulated water at the bottom of the hole and pour concrete into the bottom of the hole with a chute. When the height is more than 3m, the tandem drum should be used. When the height from the end of the string tube to the bottom of the hole is not more than 2m, and the depth of the pile hole is more than 12m, concrete conduit shall be used for grouting. Concrete shall be continuously poured, compacted by layers, and soaked and cured after pouring 12H.

(17) When pouring concrete on the pile top, the design elevation of the pile top should be properly exceeded to ensure that the elevation of the pile top meets the design requirements after removing laitance.

Six, quality control

(1) pile position control: according to the data of building survey control network and pile position layout, determine the pile position grid control network and elevation reference point, determine the pile position center, take the pile position center as the center of the circle, the radius of pile body plus the thickness of retaining wall as the radius, draw the upper circumference, sprinkle lime line as the pile hole to excavate dimension line, and after the pile position line is determined, it will be rechecked by the supervisor. With bamboo, Ф 6 or Ф 8 reinforcement, four core control points are buried outside the lime line, which is convenient for correcting the template position when installing the first section of pile hole wall protection template.

(2) Strictly control the verticality and center position of the pile hole. After the wall protection of each pile hole is completed, the axis and elevation of the pile position must be determined at the top of the wall protection, and then the pile position should be centered with crosshairs. Set the messenger wire hammer at the bottom of the well, and check the vertical flatness of the hole wall with a radius ruler. The well depth will be measured one by one according to the reference points.

(3) The final hole of the pile shall ensure the designed length of the pile and the depth into the rock. After the pile hole is dug to the design depth, the soil condition must be checked, and the pile bottom must be supported on the bearing layer specified in the design.

(4) Pile concrete shall be continuously poured by layers. Each casting height shall not exceed 1.5 m, and the thickness of each layer shall not exceed 0.5m m. When the height from the discharge port to the concrete pouring surface exceeds 2 m, a chute or bucket string must be used to prevent concrete segregation, and the concrete slump should be controlled at 70-90 ㎜. When the distance from the pile hole is less than 6 m, it is difficult to cast manually, so it can be used. Increase the concrete slump to 150- 180 ㎜, and use the impact force when the concrete slump falls to make the concrete itself compact. When it is within 6 meters from the orifice, the concrete will be poured in layers, and vibrated and compacted in layers with an internal vibrator until the pile top.

Seven, safety technical measures

(1) orifice sealing measures:

A concrete retainer must be poured around the orifice, and a fence should be set on the retainer. The fence should be 1.2m higher than the ground. The fence shall be made of steel bars and welded firmly, and the excavated earthwork shall not be piled around the orifice1m.

(2) Protective wall collapse measures:

After each pile hole is dug, the formwork for retaining wall shall be supported immediately, and retaining wall concrete shall be poured. In general, retaining wall concrete can only be removed after 24 hours. Retaining walls can be properly reinforced, and the upper and lower retaining walls should be reinforced with tie bars to avoid the phenomenon that the retaining walls crack due to their own weight due to quicksand silt. The lap length between the upper and lower retaining walls shall not be less than 50㎜. If the bottom of the pile is designed to be enlarged, if the height of the enlarged bottom exceeds 2m, the enlarged bottom shall be protected in sections to prevent the enlarged bottom from collapsing.

(3) Gas protection measures in the hole:

The underground special soil layer often contains CO2, SO2, H2S or other toxic gases, so the gas in the pile hole must be sampled and detected before each hole (quick detection tube can be used). When the content of toxic gas exceeds the allowable value, the harmful gas should be discharged to the minimum allowable concentration of chemical poisons, and adequate safety and health precautions should be taken, such as setting up special equipment to ventilate the holes, and the ventilation volume should not be less than 25L/S to prevent the occurrence of acute poisoning accidents.

(4) electric shock prevention measures:

The installation and removal of all power supplies and circuits on the construction site must be operated by certified electricians. The power supply and lines in the construction site are arranged according to the requirements of "three-phase five-wire system" and TN-S system, and are protected by classification according to "three-level distribution" and "two-level leakage". The power consumption of each well must be separated, and it is forbidden to use one brake for multiple purposes. One machine, one brake, one leakage and one box must be laid, and the wires and cables on the holes must be overhead for 20 hours. Protective measures such as moistureproof and breakage prevention, aerial workers should wear work gloves and insulating rubber shoes, and the distribution box should have strict rainproof measures, and the installation position should be appropriate and firm.

For more information about project/service/procurement bidding, and to improve the winning rate, please click on the bottom of official website Customer Service for free consultation:/#/? source=bdzd