CN100473790C - Tower crane foundation for construction and manufacturing method thereof - Google Patents

Abstract

The invention discloses a tower crane foundation for building, which comprises a tower crane foundation cap and at least four cast-in-situ piles fixedly connected under the tower crane foundation cap, and is characterized in that: the top of the cast-in-place pile exposes the base, and the cast-in-situ pile is connected to the building floor There is a water-stop structure in between. The invention also discloses the manufacturing method of the above-mentioned tower crane foundation. Aiming at high-rise buildings with super-large-area multi-storey basements, the present invention adopts high-pile cap tower crane foundations, which not only solves the problem that the tower cranes cannot be attached to the high-rise retracted podium of the main building, but also makes the layout of the tower crane foundations more flexible. The coverage area is larger, and it can be used in advance to maximize the utilization rate of machinery, which has a good effect on reducing labor consumption and reducing the construction period of the structure.

Description

Tower crane foundation for construction and manufacturing method thereof

technical field

The invention relates to a tower crane used for hoisting operations in the construction industry, in particular to a tower crane foundation and a manufacturing method thereof.

Background technique

Tower cranes are important equipment for hoisting and transportation operations in the construction industry. Most of the vertical transportation of building materials is completed by tower cranes. In order to ensure the smooth operation of the tower crane, the tower crane is installed on the foundation of the tower crane. The foundation of the tower crane must meet two requirements: one is to transmit the load on the upper part of the tower crane to the foundation evenly and not exceed the ground endurance; Under all circumstances, the overall stability can be maintained without tipping over. Therefore, the tower crane foundation is usually composed of a larger size concrete cap. In order not to affect the construction of the main body of the building, in the prior art, the tower crane foundation is usually set in the building foundation pit. During construction, it is necessary to excavate earthwork, dewater, and then make the tower crane foundation. However, if the dewatering of the deep foundation pit is stopped, the tower crane foundation will It will be soaked in water, which will affect the stability of the tower crane. Therefore, it is necessary to dewater the foundation of the tower crane separately, which will increase the construction cost.

At the same time, with the acceleration of urbanization and the development of construction technology in our country, a large number of tall and large buildings have emerged in urban construction. It is characterized by large-scale single buildings, all of which are equipped with large-scale multi-storey basements and podium buildings. The basement foundation is deeply buried, which occupies the red line of building land planning; The distance between the planes is large, which brings great difficulty to the layout and attachment of the tower crane. In order to solve this problem, it is considered to set the foundation of the tower crane in the podium. The usual method is to first drill four cast-in-place piles in the soil pit in the podium, then dewater, excavate the earth, and pour on the four cast-in-place piles. Tower crane foundation, but adopting the tower crane foundation structure in the above-mentioned prior art requires excavation, precipitation, backfilling and other operations, and the earthwork construction volume is large. After the demolition is completed, the floor is rebuilt. During this process, the site needs to be continuously dewatered, which may even result in a decrease in the waterproof performance of the building.

Therefore, using the existing technology to make the tower crane foundation, the precipitation period is long, the installation of the tower crane is difficult, and the use of the tower crane lags behind. How to reduce the requirement of dewatering operation while ensuring the foundation strength of the tower crane, and adapt to the situation of high main body and large podium of modern buildings is a difficult problem in this field.

Contents of the invention

The purpose of the present invention is to provide a tower crane foundation that can be installed in the podium of a building and will not adversely affect the waterproofing of the bottom plate of the building. Therefore, after the construction is completed, no more dewatering operations are required to adapt to the large podium of the high main building. The needs of modern architecture.

In order to achieve the above object, the technical solution adopted in the present invention is: a tower crane foundation for construction, comprising a tower crane foundation cap and at least 4 cast-in-place piles fixedly connected under the tower crane foundation cap, the top of the cast-in-place pile is exposed to the base, and A water-stop structure is arranged between the pile and the bottom plate of the building.

In the above technical solution, according to different ground conditions, different water-stop structures can be used to achieve better results.

When the building adopts a natural foundation, in order to prevent the impact caused by uneven settlement, the preferred technical solution is that the water stop structure is that an advanced water stop plate is fixedly connected with the cast-in-place pile, and the gap between the cast-in-place pile and the advance water-stop plate is fixed. Water-swelling water-stop strips are provided, and the advanced water-stop plate is connected to the building bottom plate through elastic material components, and a settlement space is reserved between the leading water-stop plate and the post-cast building bottom plate above.

Wherein, the elastic material components include a rubber waterstop that is integrally connected between the advanced waterstop and the building floor, and polyvinyl chloride on the foam plastic plates on both sides of the rubber waterstop and its lower sides and the outer side of the rubber waterstop. clay.

When the building adopts the engineering pile foundation, it can effectively avoid the influence of uneven settlement. Therefore, the preferred technical solution is that the water stop structure is an additional cap connected to the lower part of the building floor, and the additional cap and the cast-in-situ pile There is a water-swelling water-stop strip between them, and the additional cap is poured together with the building floor.

The manufacturing method of the tower crane foundation for the above-mentioned building includes determining the position and parameters of the tower crane foundation, making at least 4 cast-in-place piles, excavating the earthwork to the bottom elevation of the tower crane foundation cap, making a reinforced concrete tower crane foundation cap on the top of the cast-in-place pile and pre-embedding Tower crane bolts or tower crane standard joints, the top of the cast-in-place pile is higher than the base elevation, and the exposed part of the pile foundation is excavated together with the earthwork of the building basement, and a water-stop structure is set between the cast-in-place pile and the building floor after excavation.

When the building adopts a natural foundation, the method for setting the water-stop structure is that the method for setting the water-stop structure is to clean up the pile side; construct the floor cushion; bind the basement floor and the advanced water-stop plate reinforcement, and install the side form; The water stop strips on the pile side are fixed, and the expansion water stop strips are installed around the pile side. After cleaning the base of the pile side, the expansion water stop strips are fixed with steel nails. The laying of the water stop strips should form a closed loop; the advanced water stop plate rubber Waterstop installation; concrete pouring; among them, a settlement space is reserved between the advanced waterstop slab and the bottom slab of the post-cast building above.

When the building adopts the engineering pile foundation, the method for setting the water-stop structure is as follows: cleaning the pile side; construction of the floor cushion; binding of the basement floor and the additional cap reinforcement, and installation of the side form; fixing the water-stop strip on the pile side, The expansion water-stop strips are all installed. After cleaning the base of the pile side, the expansion water-stop strips are fixed with steel nails. The laying of the water-stop strips should form a closed loop; concrete pouring.

Due to the use of the above-mentioned technical solutions, the present invention has the following advantages compared with the prior art:

1. Because the cast-in-situ pile of the present invention exposes the base, constitutes the high pile cap structure, reduces the buried depth of the tower crane foundation, generally does not need precipitation during foundation construction, and has no slope treatment, which is safe and reliable; especially in the southern coastal areas, the permeable soil layer (powder Soil, silt layer and silt sandwiched with silty clay) are buried shallowly, and the underground water level is relatively high. The construction technology of high pile caps can avoid the necessary precipitation measures due to tower crane foundation construction.

2. Since the present invention sets an advanced water-stop structure between the cast-in-place pile and the basement floor of the building, it is not necessary to carry out subsequent precipitation, and at the same time, it is not affected by adverse geological conditions. Tower cranes can also be installed and arranged under certain geological conditions.

3. With the structure of the present invention, the tower crane can be set in the middle of the foundation pit, and the layout is flexible, which solves the problem of tower crane attachment; effectively improves the coverage of the tower crane and improves work efficiency; The engineering piles are constructed at the same time without occupying the construction period. The installation of the tower crane can be completed before the excavation of a large area of earthwork, and it can be used in advance during the construction of the basement floor.

4. For high-rise buildings with super-large multi-storey basements, the use of high-pile cap tower crane foundation not only solves the problem that the tower crane cannot be attached to the high-rise indented podium of the main building, but also makes the layout of the tower crane foundation more flexible and covering The area is larger, and it can be used in advance to maximize the utilization rate of machinery, which has a good effect on reducing labor consumption and reducing the construction period of the structure. This method solves the problem of tower crane placement in this kind of project in a targeted manner, and provides a practical approach for similar projects in the future.

5. Although the method of the present invention has more expenses for the pile foundation than the traditional natural foundation tower crane, it reduces the number of tower cranes used, and also saves a lot of construction costs (such as the secondary installation and dismantling cost of the tower crane, the labor saved by shortening the construction period) The cost of materials and machinery and the precipitation fee required for the tower crane foundation under special geological conditions) save the construction period of the structure and improve the overall benefit of the project.

Description of drawings

Accompanying drawing 1 is the schematic diagram of the facade structure of the high pile cap tower crane foundation of Embodiment 1 of the present invention;

Accompanying drawing 2 is the attachment plane schematic diagram of the high pile cap tower crane of embodiment one;

Accompanying drawing 3 is the schematic diagram of the force bearing foundation of the high pile cap tower crane;

Accompanying drawing 4 is the tower crane foundation design flowchart in embodiment one;

Accompanying drawing 5 is the construction process flowchart of embodiment one;

Accompanying drawing 6 is the schematic diagram of the connection structure between cast-in-place pile and tower crane foundation in embodiment one;

Accompanying drawing 7 is the schematic diagram of water stop structure in embodiment one;

Accompanying drawing 8 is the A-A sectional schematic diagram of Fig. 7;

Accompanying drawing 9 is the partially enlarged schematic diagram of Fig. 8;

Accompanying drawing 10 is the schematic diagram of the waterproof structure of embodiment 2 of the present invention;

Accompanying drawing 11 is the schematic diagram of reinforcing steel bars at the place where the pile penetrates the bottom plate in the second embodiment.

Among them: 1. Cast-in-place pile; 2. Bearing platform; 3. Advanced water-stop board; 4. Water-swellable water-stop strip; 5. Rubber water-stop belt; 6. Polyvinyl chloride cement; 7. Foam plastic board; 8. Additional podium.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing and embodiment:

Embodiment 1: Referring to accompanying drawings 1 to 9, a tower crane foundation for construction includes a tower crane foundation cap 2 and four cast-in-situ piles 1 fixedly connected to the bottom of the tower crane foundation cap. The height of the exposed base under the position is 5-7 meters, and a water-stop structure is arranged between the cast-in-place pile and the building floor.

The water-stop structure of this embodiment is that an advanced water-stop plate 3 is fixedly connected with the four cast-in-place piles, and a water-swelling water-stop strip 4 is arranged between the cast-in-place piles and the advanced water-stop plate. The building bottom plates are connected by elastic material components, and the settlement space is reserved between the advanced water stop plate and the building bottom plate poured after the upper part; Rubber waterstop 5, polyvinyl chloride mastic 6 on the foamed plastic board 7 and the outside of the rubber waterstop on both sides.

This embodiment is suitable for high-rise buildings with large basements and tower crane foundation construction under adverse geological conditions. Under the condition of good soil quality at the pile side, the exposed base part of the cast-in-situ pile of the tower crane foundation should not exceed 7m, otherwise corresponding structural reinforcement measures should be added.

See attached drawings 1 and 2, by using the high pile cap tower crane foundation to pass through the basement structure, the flexible and reasonable layout of the tower crane can be realized, and the problem of tower crane construction attachment can be solved. The basement structure construction stage can be used in advance, and the coverage of the tower crane construction Greatly increased, improve mechanical utilization.

Referring to shown in accompanying drawing 5, the making of above-mentioned tower crane cap foundation comprises the following steps:

(1) Tower Crane Site Selection

Tower crane site selection must consider the following factors:

① The location of the tower crane should be selected near the place where the building can be attached and the utilization rate of the tower crane can be maximized;

② When selecting the location of the tower crane, the tower crane foundation and the tower body should be considered to avoid the main beam of the building structure;

③ When selecting the location of the tower crane, the foundation pile of the tower crane should be considered to avoid the foundation cap of the building and the engineering pile;

④ When selecting the location of the tower crane, it should be considered that the tower crane can be disassembled conveniently and safely after use.

(2) Determination of tower crane foundation scheme

Attached Figure 3 is the force principle of the tower crane foundation of the high pile cap. In the figure, F is the vertical load of the tower crane, H is the horizontal load of the tower crane, M1 is the bending moment of the tower crane, and M2 is the torque of the tower crane. The torque of the tower crane can be converted into horizontal force for checking calculation .

The design process that the tower crane foundation should follow is shown in Figure 4. During the foundation design, the items that should be calculated and checked include:

① Cap shear calculation, bearing capacity check calculation and reinforcement calculation;

②Pile foundation vertical bearing capacity check;

③Pile foundation settlement calculation;

④Horizontal bearing capacity (including torque action) check calculation and displacement calculation;

⑤ check calculation of bearing capacity of pile body and buckling of pile body;

⑥ Pile reinforcement calculation.

Determine the parameters of the tower crane foundation according to the calculation results, and determine the construction plan.

(3) Construction of cast-in-situ piles

According to the different geological conditions in various places, different pile sinking techniques can be used. This embodiment is described by taking the bored pile with mud retaining wall as an example.

The construction process is as follows:

Pile positioning→burying casing→mud preparation→drilling pile machine in place→correcting level and verticality→hole cleaning→reinforcement cage making/placement→conduit→secondary hole cleaning→pouring and pounding concrete→test block setting

Construction method:

①Pile hole positioning

The axis and elevation control piles of the pile foundation should be set at places not affected by pile driving and should be properly protected. The position of cast-in-place piles shall be in accordance with the size of the design drawings, and according to the reference point of the control piles, the center point of each pile shall be accurately placed by professionals, and marked clearly, and then the gray line shall be released according to the diameter of the pile hole and casing. The allowable deviation of the placement of piles should meet the requirements specified in the "Code for Acceptance of Construction Quality of Building Foundation Engineering" (GB50202-2002).

②Buried casing

The position of the casing should be buried accurately and stably, and the space between the casing and the pit wall should be filled with clay. The slurry discharge (slurry inlet) port of the casing should be connected with the mud ditch, and the deviation between the centerline of the casing and the centerline of the pile position shall not be greater than 50mm.

The buried depth of the casing should not be less than 1m in cohesive soil, and should not be less than 1.5m in sandy soil and soft fill. The top of the casing should be 100-200mm above the ground.

The casing generally uses a tool type steel casing. Casing inner diameter should be larger than drill bit diameter.

③ Preparation of mud

Corresponding mud treatment facilities such as mud storage tanks and sedimentation tanks shall be set up at the initial stage of construction. When preparing mud, it should be fully stirred and impurities such as stone particles should be removed through vibrating screens and cyclones. After sedimentation, it should be put into the mud storage tank for standby. The mud that circulates through the mud pool and is replaced when pouring underwater concrete is also purified and regenerated through vibrating screens, cyclones, sedimentation tanks, etc.

④ Positioning of bored pile driver and correction of horizontal and vertical

The drilling rig should be kept balanced when in place, so as not to tilt or shift during drilling operations. When a rotary drill is used, the verticality of the drill pipe should be measured in two directions in advance with theodolite or hanging hammer, so that the vertical deviation of the drill pipe should be controlled within 2‰.

The drill bit should be accurate to the hole. The deviation between the center of the drill bit and the center of the casing should be controlled within 15mm. When it is a percussion drill, it should be controlled within 30mm.

After the drilling rig is adjusted, it should be fixed at the bottom of the drilling rig according to the specific structure of the model, and reliable measures should be taken to prevent the rack from being displaced due to force during drilling.

⑤ hole clearing

Drilling is generally performed at a slow speed at the beginning. After the hole is more than 5m long, the verticality of the drill pipe can be checked to ensure the allowable deviation of the verticality of the hole. When all aspects are operating normally, the speed can be started. When entering the bearing layer, you should start with a slow speed according to the specific conditions of the soil layer, and then gradually speed up. For silt and muddy soil and soil layers that are prone to hole collapse, the speed should be reduced to the slowest, and the mud circulation speed should be reduced and the relative density of the mud should be increased to avoid scouring the hole wall due to excessive eddy currents in the mud. After every 4-5m of drilling and treatment of hole inclination, necking, and hole collapse, the verticality and diameter of the drilled hole should be checked in time. Generally, a hole detector can be used to check, so that problems can be found and dealt with in time.

When the hole is drilled to the depth required by the design, the hole cleaning should be started. For drilling holes with good soil quality and positive cycle operation using raw soil slurry, the drilling rig can be idled without drilling footage, and the drilling slag is basically eliminated before water injection. Then replace it with mud with a small relative density. When the relative density of the discharged mud is equal or similar to that of the incoming mud, it is qualified to clear the hole when there is no sand grain feeling in the hand-twisted mud. When it is a reverse circulation operation, clean water or mud should be put in from the mouth of the casing according to the soil quality, and the hole should be cleared by changing the slurry. When the relative density of the discharged mud reaches the same index as that of the positive circulation operation, it is qualified.

Before the completion of hole cleaning, a slurry sample should be taken at a distance of 200-500mm from the bottom of the hole. Drilling reaches the design elevation. Before pouring concrete, the relative density of the mud within 500mm of the hole bottom should be <1.25, the sand content should be ≤8%, and the viscosity should be ≤28S. Before pouring concrete, the thickness index of sediment at the bottom of the hole should meet the following requirements: end-bearing piles ≤ 50mm, friction piles ≤ 150mm.

During the whole process of forming and clearing holes, special personnel should frequently inspect and make construction records.

When necking and hole collapse occur during drilling, clay blocks should be put in immediately to make the drill bit idle at a slow speed without drilling footage, and reduce the mud input speed to solidify the wall, and then drill through at a slow speed. When the mud leaks suddenly, the clay should be backfilled immediately according to the above method, and the drilling should not start until the mud level does not drop. When the drilling hole is inclined or the hole diameter is irregular, the drill can be lifted back and forth to sweep the hole from top to bottom.

⑥ Rebar production

The steel cage can be finished at the base and then transported to the site for use. The reinforcement cage should be made according to the design drawings, and it should have a certain rigidity and integrity to ensure that it will not be deformed during transportation and hoisting. It is advisable to use spiral or welded ring-shaped stirrups, which are welded to the main reinforcement point by point. The lower opening of the reinforcement cage should be slightly bent into an inverted cone shape, so that it is more convenient to hoist into the hole. The production standards are controlled according to the design drawings and specifications, and the inspection standards are shown in the table below.

Table Concrete Reinforcement Cage Quality Inspection Standard Table

serial number content Allowable deviation (mm)

1 Main rib spacing ±10 2 Stirrup spacing or helix pitch ±20 3 Steel cage diameter ±10 4 Reinforcement cage length ±100

Place the reinforcement cage based on the height of the cage top, and the allowable deviation of the height is ≤±100mm. After the reinforcement cage is hoisted and straightened vertically, it is slowly lowered to the bottom along the guide reinforcement (pipe), and then the guide reinforcement is hoisted. Generally, the guide steel bar can not reach the bottom, only 1/2 of the hole depth or 6-8m long can be used, and it can be fixed temporarily. Rebar welding. If the reinforcement cage is too long and limited by the lifting height, the reinforcement cage can be hoisted into the holes in sections and lengthened at the opening.

⑦ Catheter

The diameter of the catheter is generally 200-250mm, and the wall thickness should not be less than 3mm according to the size of the aperture. When assembling, the upper end should be composed of several 1-2m short pipes, the lower end can be long pipes, and the bottom end of the pipe should be welded with stiffening hoops. The pipe-to-pipe joints are connected with screws, and can also be connected with flanges.

The conduit should be installed in the center of the pile hole. If a water stopper is used, the distance from the bottom of the conduit to the bottom of the hole must be 300mm to 500mm larger than the length of the water stopper to ensure that the water stopper is discharged from the bottom of the pipe smoothly. The catheter should be sunk into the bottom of the hole, raised after marking, and fixed after meeting the above requirements. The upper opening of the conduit shall be directly connected to the lower opening of the concrete storage hopper, and shall be at an appropriate distance above the mud surface, generally not less than 3m.

⑧Secondary hole cleaning

Before concrete pouring, the thickness of the sediment at the bottom of the hole must be re-measured, and if it exceeds the requirements, the hole should be cleaned again. The relevant procedures and standards for hole cleaning are in line with the content of the above step ⑤ hole cleaning.

⑨Pouring concrete

Before pouring, do the duct sealing test to prevent air leakage and water leakage. During the initial pouring, the amount of initial pouring should be such that the bottom end of the conduit can be buried in the concrete 0.8m ~ 1.2m at a time.

As the concrete rises, the conduit is also lifted or dismantled accordingly, but the bottom of the pipe end should be buried 2 to 3m below the concrete surface, and should not be greater than 6m, and in any case not less than 1m. Concrete should be poured continuously without interruption, and the pouring speed should be accelerated.

The pouring elevation of the concrete surface at the top of the pile must be at least 1 times the pile diameter higher than the design elevation, and ≥ 0.5m, and it must be observed that the emerging concrete does not contain mud, so that after the pile top concrete is removed, the designed pile top can be guaranteed. Surface concrete quality.

⑩Test block making

During pouring, concrete samples are randomly selected on site to make test blocks for curing under the same conditions, and the tower crane is sent for pressure testing before installation.

This completes the cast-in-place pile construction.

(4) Pile foundation detection

The pile foundation shall be inspected for the integrity of all piles in accordance with the requirements of the "Code for Construction Quality Acceptance of Building Foundation Engineering" (GB50202-2002).

(5) Tower crane foundation construction

The construction process of the tower crane foundation is as follows:

Positioning and setting out and elevation measurement→excavation of foundation soil→pouring of concrete cushion→connection treatment of piles and caps→construction of foundation reinforcement and formwork→pre-embedment of tower crane bolts→pouring of foundation concrete→concrete curing

Construction methods include:

①Positioning and laying out and height measurement

According to the pile hole cross line marked by the cast-in-situ pile, release the outer edge of the cap; according to the site standard elevation and related design documents, determine the elevation of the cap and the depth of earthwork excavation.

② Foundation earthwork excavation

According to the determined excavation depth, excavate to the design elevation.

③Concrete cushion pouring

After the excavation of the earthwork is completed, according to the released edge line, the concrete formwork of the cushion layer is supported by wooden squares, and the concrete is poured.

④ Connection between pile and tower crane foundation

After foundation excavation, in order to facilitate the control of pile elevation, it is considered that the processing of pile cutting should be carried out after pouring of concrete cushion. The concrete of the cast-in-situ pile is chiseled out according to the design elevation of the pile top, and the longitudinal steel bar of the pile is directly anchored to the foundation of the tower crane. The anchorage length shall not be less than 40d (d is the diameter of the steel bar); See Figure 6 for the detailed connection structure.

⑤ Tower crane foundation reinforcement, formwork construction and tower crane bolt pre-embedding

According to the basic reinforcement determined in the plan, after re-checking the reinforcement samples, the bill of materials will be delivered to the workshop for production, transported to the site in time, and classified and stacked according to the component number.

D≥22mm steel bars are connected by equal-strength butt welding or mechanical connection, and the rest can be connected by lap joints. The number of steel bar joints on the same section shall not exceed 50% of all steel bars, the joints of steel bars shall be staggered, and the distance between adjacent joints shall not be less than 36d. The quality of the steel bar connection joints should meet the requirements of the corresponding acceptance specifications, and the connection test pieces should be prepared in advance.

The type, specification and spacing of the steel bars used in the foundation of the tower crane should be bound strictly according to the design drawings, and the steel bar protective layer pads should be set up.

18-thick wood plywood is used for tower crane foundation and other templates (50×100 wood squares are used for the back block and corrugated wood of the glued template), and the support system adopts ф48×3.5 steel pipe fastener system. The basic template is set up according to the basic edge released by the on-site personnel.

According to the spacing and material selection indicated in the tower crane manual, pre-embed the tower crane foot bolts, and the pre-embedded bolts can only be used after passing the inspection.

⑥ Concrete pouring of tower crane foundation

The foundation concrete is poured directly into the mould, using an automobile pump. Concrete is poured in layers, and vibrated with an inserted vibrator to avoid vibration leakage (the distance between the insertion points of the vibrator should be ≤@300; when pouring the upper layer of concrete, the depth of the vibrator inserted into the lower layer of concrete should be ≥100), and vibrate Pound until no air bubbles come out on the surface of the concrete.

⑦ Concrete maintenance

The maintenance of concrete should be carried out by special personnel, and wet grass bags should be covered on the surface of concrete components for heat preservation and moisturizing maintenance. Concrete curing time and related requirements shall be implemented in accordance with the regulations.

(6) In actual construction, tower crane installation can be carried out at the same time

The installation of the tower crane should be carried out in strict accordance with the relevant regulations of the tower crane manual and the "Technical Regulations for the Use and Installation of Construction Machinery" JGJ33-2001. During the installation process, technical inspections must be carried out in stages. After the installation is completed, the technical inspection and adjustment of the whole machine should be carried out, and it can be delivered for use after passing the inspection.

(7) Excavation of earthwork between piles

The excavation of the exposed part of the pile foundation is excavated together with the earthwork of the basement. In order to avoid damage to the pile body by mechanical excavation, the earthwork between the piles and within 1000mm around the outside of the pile are manually excavated in layers and symmetrically. During the entire earthwork excavation process Real-time monitoring of pile foundations.

(8) Treatment of the relationship between the tower crane foundation of the high pile cap and the surrounding structure of the building

Pile foundation through the bottom plate treatment:

This embodiment is applicable to the occasion where the building adopts natural foundation, and the technological process of its floor treatment is as follows:

Pile side cleaning→base plate cushion construction→basement bottom slab and advanced waterstop bottom slab reinforcement binding, side formwork installation→pile side waterstop fixation, advanced waterstop bottom plate rubber waterstop installation→concrete pouring→tower crane dismantle after stop using → The foundation of the high pile cap tower crane is chiseled to the top surface of the advanced water stop slab → The sand and gravel cushion is filled → Part of the post-cast reinforcement connection and construction joint treatment → Part of the post-cast concrete pouring

Under the geological conditions with high confined water level, in order to prevent the tower crane foundation from passing through the basement structure for construction and precipitation, an advanced rubber waterstop bottom plate is set around the foundation pile of the tower crane to meet the deformation and settlement needs between the pile foundation and the natural foundation raft foundation , to avoid adverse effects on the original basement structure, the specific location and method are shown in attached drawings 7 to 9.

The part of the waterstop is poured together with the surrounding floor, and 200mm is reserved for the upper part. After the tower crane foundation is removed, sand and gravel cushions are used to fill the bottom of the basement floor as a bottom formwork for the post-casting plate belt. The remaining parts are the same as the post-casting belt method. The junction of the water stop board and the building floor is connected by a rubber water stop 5, and the upper and lower sides of the rubber water stop are provided with a 50mm polyethylene foam plastic plate 7, and its outer side is a polyvinyl chloride cement 6.

The expansion water-stop strips are installed around the pile side. After cleaning the base of the pile side, the expansion water-stop strips are fixed with steel nails. The laying of waterstop strips should form a closed loop, and no breakpoints should be left during the extension of the laying. The spacing of embedded iron nails must be strictly controlled, and its density must meet the stability requirements for laying waterstop strips.

The junction between the bottom plate and the tower crane pile foundation is set according to the post-casting belt, and the steel bars are reserved for inserting bars, and the reinforced steel bar is added to the part of the post-casting belt with half the cross-section of the original steel bar. The steel bars at the disconnection are mechanically connected after the tower crane foundation is removed.

The post-casting part shall be constructed after the pile foundation is chiseled out. The concrete of the post-casting part shall be poured with shrinkage-compensated concrete with the same impermeability grade as the adjacent structural concrete and a higher concrete strength grade. The curing time shall not be less than 28 days.

Anti-leakage measures:

The concrete at the opening of the roof is made of micro-expansion waterproof concrete one level higher than the structural concrete, and an additional waterproof layer is set on the roof. Mechanical connections are used to disconnect the steel bars at the openings. Concrete shall be poured with shrinkage-compensated concrete with the same impermeability grade as the concrete of the adjacent structure, and a higher concrete strength grade; after the pouring is completed, the maintenance work shall be done in time, and the curing time shall not be less than 14 days.

Embodiment 2: Referring to accompanying drawings 10 and 11, a tower crane foundation for construction includes a tower crane foundation cap 2 and four cast-in-situ piles 1 fixedly connected to the bottom of the tower crane foundation cap. The height of the exposed base under the position is not less than 3 meters, and a water-stop structure is arranged between the cast-in-place pile and the building floor.

The water-stop structure of this embodiment is an additional cap 8 connected to the lower part of the building floor, and a water-expandable water-stop strip 4 is arranged between the additional cap and the cast-in-place pile, and the additional cap is poured together with the building floor.

This embodiment is applicable to the occasion where the building adopts the engineering pile foundation, and its manufacturing method is similar to Embodiment 1, wherein, the difference is the treatment of the bottom plate, and the technological process of the bottom plate treatment is:

Pile side cleaning→floor cushion construction→basement bottom slab and additional cap reinforcement binding, side formwork installation→pile side water stop strip fixing→concrete pouring (reserve 50mm for the slab around the pile before pouring)→remove the tower crane after it stops using→ The tower crane foundation of the high pile cap is chiseled to the top surface of the floor → 50mm is reserved for filling with fine stone concrete

According to the thickness of the bottom slab, two structures can be adopted: additional cap under the bottom slab and no additional cap under the bottom slab. Attachment 10 is a schematic diagram of the structure of the additional cap. For the water-stop strip, 50mm is reserved for the slab surface when pouring the bottom slab. After the tower crane pile foundation is chiseled off, fill it with fine stone concrete of the same grade.

The concrete at this place is poured with shrinkage-compensated concrete with the same impermeability grade as the concrete of the adjacent structure and a higher concrete strength grade, and the curing time is not less than 14 days.

Reinforcing steel bars are provided at the section where the bottom plate steel bar is cut off by the pile body, and its structure is shown in Figure 11.

In order to verify the practicability of the inventive method, the applicant of the present invention carried out an engineering test in a confidential state in a construction site undertaken by himself, and the test results are as shown in the following application examples:

Application example one:

The main civil engineering and installation project of Dongsheng Pedestrian Street is located on Shishi Road, Shengze Town, Wujiang City, opposite to Hongsheng Hotel. It is divided into three areas: A, B, and C during design. The total construction area of the project is 102,838m ² , of which the basement floor is about 23,000m ² , which is an underground supermarket, garage and equipment room, part of which is also used as civil air defense, and has a frame structure. The ground is composed of three blocks A, B, and C, interconnected with each other, with an area of about 80,000m ² , and the 1st-5th floors are commercial podiums of about 60,000m ² ; Blocks B and C each have a 16-story apartment building, and the area of the two apartments is A total of about 20,000m ² is a frame-shear structure. Due to the large volume of the project, the tight construction period, and the construction of the large basement and podium, the tower crane based on the high pile cap was selected, which not only solved the problem that the tower crane could not be attached to the high-rise part in the middle of the podium, but also rushed in The installation of the tower crane before the end of the earthwork excavation created conditions for the construction of the basement, saved 10 days of the construction period of the basement, and saved a comprehensive construction cost of 150,000 yuan.

Application example two:

Suzhou Industrial Park Haitian Plaza project covers an area of 19354m ² , with a total construction area of 168478.77m ² , 125801m ² above ground and 42677m ² underground, of which Area A: 26882m ² shopping malls, 34873m ² office buildings; Area B: 26645m ² shopping malls, 37401m ² high-rise apartments . The project has 2 floors in the basement and 2 towers on the ground: the 20-story office building has a building height of 77.75m (2-6 axis/B-J axis), and the 22-story apartment building has a building height of 77.60m (17-25 axis/B-J axis) , composed of 4 floors of podium. The project has a large volume and foundation pit protection measures are adopted around the foundation pit. The basement area is close to the foundation pit enclosure. There is no space for the traditional tower crane foundation, and the high-rise part is indented in the middle of the podium, and the attachment length of the tower crane is limited. Based on the above situation, the applicant selected the high pile cap foundation as the foundation of the two tower cranes used in this project. The foundation pile of the tower crane adopts ￠850mm concrete pouring pile, and the upper part is equipped with a square cap foundation of 5000×5000×1350. The actual test shows that the tower crane foundation of the high pile cap has achieved good results, and the effect of the tower crane has been maximized, saving the construction period by 10 days. Compared with the traditional foundation form, it has saved a comprehensive construction cost of 60,000 yuan.

Application example three:

The N2N5 project of Times Square in Suzhou Industrial Park is a frame-shear structure, N2 is two floors underground, nine and nineteen floors above ground; N5 is two floors underground, two to three floors above ground, with a total construction area of 127323m ² 84651m ² , N5 area is 47071.5m ² ), the total building area of the basement is 47577.4m ² , (N2 basement area is 18381m ² , N5 basement area is 29196.4m ² ), the total height of N2 is 80.80m, and the total height of N5 is 15.50m. The construction site of the project is narrow, the basement sideline is close to the sideline of the foundation pit enclosure, and the basement volume is quite large. The construction period needs to be completed within 120 days. In view of the above situation, the traditional tower crane foundation placement is not only limited by space and utilization rate, but also The high-rise part of N2 cannot be attached, so the tower crane foundation with high pile caps is used. The tower crane foundation construction is carried out at the initial stage of earthwork excavation. Completing the construction created good conditions and saved 5 days of construction period. Only based on the N5 project calculation, compared with the use of 4 tower cranes and the traditional foundation form, the construction cost has been saved by 336,000 yuan.

Claims (2)

1. tower crane foundation for construction, comprise tower crane cushion cap [2] and be fixedly connected at least 4 castinplace piles [1] of tower crane cushion cap below, substrate is exposed at described castinplace pile top, be provided with water-stopping structure between castinplace pile and building base plate, it is characterized in that: described water-stopping structure is, be fixedly connected with leading seal plate [3] with described castinplace pile, be provided with water-swellable sealing rod [4] between castinplace pile and leading seal plate, be connected through the elastomeric material member between described leading seal plate and building base plate, reserve settlement space between the building base plate that waters behind leading seal plate and the top; Described elastomeric material member comprises, is arranged at the polyvinyl chloride (PVC) cement [6] in rubber fastening band [5], the plastic foamboard [7] that is positioned at the upper and lower both sides of rubber fastening band and the outside thereof that leading seal plate links to each other with one in the building base plate.

2. the manufacture method of the described tower crane foundation for construction of claim 1, comprise, determine tower crane position and parameter, make at least 4 castinplace piles, earth excavation is to tower crane cushion cap bottom absolute altitude, make steel concrete tower crane cushion cap and pre-buried tower crane bolt or tower crane standard knot at the castinplace pile top, described castinplace pile top is higher than the substrate absolute altitude, carry out pile foundation exposed parts soil excavation with the building basement earthwork, the excavation back is provided with water-stopping structure between castinplace pile and building base plate, it is characterized in that: the described method that water-stopping structure is set is the cleaning of stake side; The base plate cushion construction; Basement bottom board and leading seal plate reinforcing bar binding, side form are installed; Stake side sealing rod is fixed, and around the stake side expansion sealing rod is set all, after stake side group layer is cleaned out, adopts steel nail fixed expansion sealing rod, and the laying of sealing rod should form closed circuit; Leading seal plate rubber fastening band is installed; Concreting; Wherein, reserve settlement space between the building base plate that waters behind leading seal plate and the top.

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