CN105442591A - High-performance low-prestressed concrete hollow square pile - Google Patents

High-performance low-prestressed concrete hollow square pile Download PDF

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Publication number
CN105442591A
CN105442591A CN201510752024.7A CN201510752024A CN105442591A CN 105442591 A CN105442591 A CN 105442591A CN 201510752024 A CN201510752024 A CN 201510752024A CN 105442591 A CN105442591 A CN 105442591A
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pile
concrete
terminal pad
mold
hollow square
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陈玉龙
柳志富
王德利
刘婧
吕晓庆
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WEIHAI QIDE NEW BUILDING MATERIALS Co Ltd
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WEIHAI QIDE NEW BUILDING MATERIALS Co Ltd
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    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D5/00Bulkheads, piles, or other structural elements specially adapted to foundation engineering
    • E02D5/22Piles
    • E02D5/58Prestressed concrete piles
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B28WORKING CEMENT, CLAY, OR STONE
    • B28BSHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B23/00Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects
    • B28B23/02Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects wherein the elements are reinforcing members
    • B28B23/04Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects wherein the elements are reinforcing members the elements being stressed
    • B28B23/06Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects wherein the elements are reinforcing members the elements being stressed for the production of elongated articles
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D5/00Bulkheads, piles, or other structural elements specially adapted to foundation engineering
    • E02D5/22Piles
    • E02D5/24Prefabricated piles
    • E02D5/30Prefabricated piles made of concrete or reinforced concrete or made of steel and concrete
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D5/00Bulkheads, piles, or other structural elements specially adapted to foundation engineering
    • E02D5/22Piles
    • E02D5/52Piles composed of separable parts, e.g. telescopic tubes ; Piles composed of segments
    • E02D5/523Piles composed of separable parts, e.g. telescopic tubes ; Piles composed of segments composed of segments

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  • Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Mining & Mineral Resources (AREA)
  • Paleontology (AREA)
  • Civil Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Piles And Underground Anchors (AREA)

Abstract

The invention discloses a high-performance low-prestressed concrete hollow square pile. The high-performance low-prestressed concrete hollow square pile is characterized in that a pile body is composed of at least one unit pile; each unit pile is composed of concrete and parallel reinforcing steel bars tensioned with the prestress of 0.3-0.6 [sigma] in the concrete; the two ends of the reinforcing steel bars are connected with connection plates respectively; the adjacent unit piles are welded through the connection plates to form the pile body; the outer layers of the two connected connection plates are coated with fiber resin with the thickness not smaller than 1.5 mm; the fiber resin layers are wrapped with carbon fiber cloth capable of improving the antiseptic ability and tension resistance. The high-performance low-prestressed concrete hollow square pile has the advantages of being high in corrosion resistance, large in bearing force, low in production cost, high in durability and the like, the problem of the piling illusion is effectively solved, the integrity of the pile body is ensured during construction, the bearing force of the pile body is effectively improved, the weight is lower, cracks caused by mutual collision in the production and transportation process can be avoided, and the phenomena of pile breakage, pile body concrete falling and the like are also not prone to occurring in the site construction.

Description

High-performance lower-prestressed concrete hollow square pile
Technical field
The present invention relates to the basis of building, specifically a kind of easy construction, long service life, high-performance lower-prestressed concrete hollow square pile that anti seismic efficiency is good.
Background technology
As everyone knows, stake is the basis of building, and first building stability needs reliable pile foundation, for this reason, proposes technical requirements specially in " technical code for building pile foundation " (JGJ94-2008) to concrete pile.In current construction, general employing is prestressed concrete solid pile, if the patent No. is 2012100044922, patent name is " prestressed concrete solid pile and preparation method ", it contains reinforcing cage, concrete, reinforcing cage is combined integrate structure, the independent body reinforcing cage adopting slip welding method to be welded respectively by least two welds or colligation forms, pile body two ends are provided with the metal end plate be connected with reinforcing cage, the stirrup of reinforcing cage is welded on main muscle in the shape of a spiral, the main muscle of reinforcing cage adopts prestressed concrete pile high pre-stress rod iron, its prestressing force 0.7-0.9 [σ] stretch-draw, its intensity meets every square millimeter and is greater than 1420 Ns, because every reinforcing cage all adopts slip welding method to be welded, the structural strength of reinforcing cage own is improved greatly, Joint Strength loss is less than or equal to 5%, the diameter of the main muscle of reinforcing cage prestressing force reduces 20%, the deficiency of this high pre-stress concrete solid square pile: one is that design is unreasonable, Main Function due to stake bears building load, but what this high pre-stress concrete solid square pile adopted is high pre-stress rod iron, as Chan Sheng Transverse is excessive to the deflection of stake during power in use procedure, affect the safety of building, two is that connection between pile body does not have safeguard measure, and antiseptic property is poor, three is adopt common concrete, its cracking resistance is poor, have impact on the durability of preformed pile, owing to there is crack, air or corrosive medium easily and reinforcing bar and concrete produce chemical action, reduce the safety of pile body, the reduction in building application life when particularly using in the environment that the corrosivity such as ocean, saline-alkali soil is strong, can be accelerated.
Summary of the invention
The object of the invention is to solve above-mentioned the deficiencies in the prior art, provide that a kind of corrosion resistance is strong, the high-performance lower-prestressed concrete hollow square pile of long service life.
The technical solution adopted in the present invention is:
A kind of high-performance lower-prestressed concrete hollow square pile, comprise pile body, pile crown, the stake of at least one joint unit of pile body forms, it is characterized in that unit stake cross section is that central authorities establish round-meshed side's shape shape, the reinforcing bar that the pile lining of unit stake is 0.1 σ-0.8 σ by the prestressing force be parallel to each other in concrete and concrete forms, the two ends of unit stake are respectively equipped with terminal pad, the two ends of reinforcing bar are connected with terminal pad respectively, adjacent cells stake forms pile body through terminal pad welding, the fibre resin of the two terminal pads outer brushing thickness 0.5-2.5mm be connected, fiber reinforced resin layer is wound around again the carbon cloth that can improve antiseptic power and resistance to tension, its production technology is as follows:
Step one, production unit pile die, unit pile die is concrete by external mold, internal mold concrete, internal mold fixed support, reinforcing cage fixed support, steel bar tensioning device form, described external mold is specifically fixedly connected into the side template of both sides is mutually vertical by soffit formwork, it is circular mast or pipe that described internal mold is specially an external diameter cross section, described steel bar tensioning device is made up of detent mechanism and stretch-draw mechanism
Step 2, make reinforcing cage, reinforcing cage is that the regular screw threads reinforcing bar of 0.1 σ-0.8 σ and terminal pad form by the prestressing force be parallel to each other, terminal pad is outer mold body section shape, central authorities are provided with the through hole of inner mold body diameter size, the two ends of regular screw threads reinforcing bar are connected with the two ends of terminal pad respectively, the regular screw threads reinforcing bar be parallel to each other in two terminal pads is welded by connecting reinforcement or ties up the reinforcing cage being made into tubular, the terminal pad of reinforcing cage one end is provided with the locating ring be connected with detent mechanism, the terminal pad of the other end of reinforcing cage is provided with the connecting ring be connected with stretch-draw mechanism, reinforcing cage is put into external mold concrete and located by reinforcing cage fixed support,
Step 3, installation internal mold are concrete, are specifically positioned in the concrete interior reinforcing cage of external mold by internal mold fixed support by internal mold,
Step 4, to be exerted a force to terminal pad by steel bar tensioning device, carry out lower-prestressed stretch-draw to the regular screw threads reinforcing bar be parallel to each other of composition reinforcing cage, make that regular screw threads are prestressed, reinforced to be 0.1 σ-0.8 σ and to keep stretch-draw, optimum prestress is 0.3 ~ 0.6 σ,
Step 5, make antirust, that impermeability is strong concrete, concrete is made up of cement 15-25%, husky 25-40%, stone 35-65%, water reducing agent 0.01-1% and corrosion inhibitor 0.01-1%, and cement adopts strength grade to be not less than the sulfate resisting cement of 42.5 grades or portland cement, the Portland cement of treated (mixing Admixture or the mineral admixture of sulfate resistance); Fines should adopt clean natural hard medium coarse sand, and fineness modulus is preferably 2.8-3.1, and when adopting manufactured sand, fineness modulus can be 2.9-3.3; Coarse aggregate should adopt rubble, continuous grading, and flat-elongated particles is no more than 10%, and mud content should be not more than 1%, and maximum particle diameter should not be greater than 35mm, and should not exceed 3/4 of distance of reinforcing bar; For improving antiseptic property, mixing the Admixtures such as the high efficiency water reducing agent of 0.01-5%, sulfate resistance Admixture and reinforcing steel bar corrosion inhibitor, also can mix the mineral admixtures such as 0.01-20% silica flour or flyash,
Step 6, be coated with one deck interleaving agent at cast inner mold external surface, square outer mold inner surface, by the high performance concrete feeding mould for preparing and after hand punning or centrifugal dense concrete,
Step 7, when pile strength reaches 40 ~ 80%, unclamp steel bar tensioning device and dismantle mold, and according to design length, the terminal pad of unit mould through its end being weldingly connected into pile body,
Step 8, clean pile body terminal pad surface also brushing thickness are not less than the fiber reinforced resin layer of 0.5-2.5mm, and optimum thickness is less than 1.5mm, fiber reinforced resin layer is wound around again the carbon cloth that can improve antiseptic power and resistance to tension.
The yield strength value of plain bars of the present invention is 300N/mm 2-500N/mm 2plain bars, the two ends of plain bars are weldingly connected with terminal pad respectively.
High performance concrete of the present invention, while mobility needed for guarantee concrete batching system, reduces water supply volume as far as possible, and reduce water/binder ratio, make concrete total pore space, particularly capillary interstice rate significantly reduces.Cement, after the stirring that adds water, can produce a kind of flocculence structure.In these flocculence structures, be wrapped in many mixing waters, thus reduce the workability of green concrete.In order to keep the workability needed for concrete batching system in construction, just correspondingly must increase water supply volume when mixing and stirring, will impel in water mudrock structure forming too much hole like this.When adding aligning of water reducing agent, make cement particle surface all with identical charges.Under the effect of electrical repulsion, not only make cement system be in metastable suspended state, also form one deck solvation moisture film at cement particle surface, make the free water in Flocculated Cement body discharge simultaneously, thus reach the object of diminishing.Much research shows, when water/binder ratio is reduced to below 0.38, the target eliminating capillary interstice just can realize, and mixes high efficiency water reducing agent, water/binder ratio can be reduced to less than 0.38 completely.
The deficiency of hydrate stability in the Behavior of Hardened Cement Paste of ordinary concrete is that concrete can not another principal element of super-durable.In ordinary concrete, mix the object of active mineral, be to improve the composition of the gum material of Behavior of Hardened Cement Paste in concrete.Containing a large amount of active SiO in active mineral additives 2and active A l 2o 3their can and cement hydration process in the free lime that produces and high alkalinity aquation silicon acid calcium generation secondary response, generate the low alkalinity aquation silicon acid calcium that intensity is higher, stability is more excellent, thus reach the composition improving aquation gum material, eliminate the object of free lime, make water mudrock structure more fine and close, and block the infiltration road that may be formed.In addition, can also improve and gather materials and the interfacial structure of Behavior of Hardened Cement Paste and boundary zone performance.These important effects, have the contribution of internal to the concrete durability of enhancement and intensity.
Advantageous effect of the present invention is:
(1) compared with hollow shell pill, concrete corrosion allowance can be increased; Compared with castinplace pile, it does not contact with corrosive substance in formation of pile; (2) compared with pile tube, when volume of concrete is identical, the surface area of square pile is larger, significantly can improve bearing capacity of friction pile; (3) high-performance lower-prestressed concrete hollow square pile adopts hollow-core construction process, and save raw material, cost of production reduces greatly, meets green construction requirement; (4) protection at terminal pad place and the size of Shi Hanzhang etc. are through appropriate design, the resistance to corrosion of concrete hollow square pile is improved greatly, the life requirement of moderate corrosion and general deep-etching can be met completely, (5) adopt hollow concrete prefabricated in the above scope of high-performance lower-prestressed concrete hollow square pile pile top 2m, ensure that pile body integrity when square pile is constructed.Pile foundation construction need pass through there is more boulder and obstruction in thicker harder interlayer or place time, often a kind of illusion of piling can be seen: after the pile concrete near the pile top of a pile is broken, the above pile concrete in broken place continuously destroys along with top impact pile driving, outwardly, the hammering downward injection of pile body once a bit, these hammering energies are all for destroying bottom shaft concrete and being expressed in the soil layer of surrounding by its fragment in fact, and piling embedded depth is only an illusion.Piling artefact problems can be effectively solved by doing hollow process within the scope of pile top 2 meters, ensure that the integrality of pile body during construction, also effectively improve the bearing capacity of pile body simultaneously, (6) high-performance lower-prestressed concrete hollow square pile bearing capacity of pile than square pile of the same type and pile tube higher; Because pile body position is identical with the structure of pile tube, be all hollow, external overall shape or square, therefore pile body external surface area is than pile tube larger of identical caliber, and improving bearing capacity for friction pile has significant impact.This high-performance lower-prestressed concrete hollow square pile has the advantage of square pile and pile tube concurrently simultaneously, bearing capacity is relatively higher, (7) high-performance lower-prestressed concrete hollow square pile weight is lighter, production and transport is convenient, more not easily crack is produced during construction, this square pile adopts hollow-core construction process, compare square pile weight of the same type lighter, crack can not be produced owing to mutually colliding during production and transport, also not easily broken pile is produced during site operation, pile concrete falls the phenomenons such as block, (8) high-performance lower-prestressed concrete hollow square pile pile concrete is more closely knit, more can ensure the integrality of pile body, compactness, because square pile adopts the hollow-core construction identical with pile tube, therefore centrifugal process can be adopted to produce in production square pile flow process, but not the artificial vibrated concrete of plain hollow square pile, significantly improve the compactness of pile concrete, bearing capacity of pile improves greatly, (9) high-performance lower-prestressed concrete hollow square pile adopts hollow-core construction process, save raw material, cost of production reduces greatly, meet green construction " material-saving and material resources utilize technology " and builing industry New technical use " concrete technology ", construction work green construction " material-saving and material resources utilize technical essential " comprises and " promotes the use of high performance concrete, reduce resource consumption ".Builing industry New technical use " concrete technology " comprises " high durability concrete, high-strength high-performance concrete ".This square pile adopts strong concrete, the multiple high performance additive of admixture, improves multiple index such as impermeability, intensity of pile concrete.Also more raw material are saved when hollow-core construction is produced, effective reduction cost of production, (10) safety and the durability of pile foundation is met, after the construction of high-performance lower-prestressed concrete hollow square pile, the prefabricated filling core block shutoff of pile crown, completely cut off the hazardous substancess such as extraneous aggressivity and entered the inner accelerate concrete corrosion of pile body, meet safety and the durability of pile foundation.
Accompanying drawing explanation
Fig. 1 is a kind of structural representation of the present invention.
Fig. 2 is the structural representation of terminal pad in the present invention.
Detailed description of the invention
The invention will be further described below:
As shown in the figure, a kind of high-performance lower-prestressed concrete hollow square pile, comprise pile body 1, pile crown 2, the stake of at least one joint unit of pile body 1 forms, it is characterized in that unit stake cross section is that central authorities establish round-meshed side's shape shape, the reinforcing bar 4 that the pile lining of unit stake is 0.1 σ-0.8 σ by the prestressing force be parallel to each other in concrete and concrete forms, the two ends of unit stake are respectively equipped with terminal pad 3, the two ends of reinforcing bar 4 are connected with terminal pad 3 respectively, adjacent cells stake forms pile body through terminal pad welding, the thickness of terminal pad 3 is 8-16mm, terminal pad 3 is positioned at unit pile die both ends, terminal pad 3 spacing is the length of unit stake, be generally 1.0-2.0mm, terminal pad 3 plays the connection between unit stake, the fibre resin of the two terminal pads 3 outer brushing thickness 0.5-2.5mm be connected, fiber reinforced resin layer is wound around again the carbon cloth that can improve antiseptic power and resistance to tension, its production technology is as follows:
Step one, production unit pile die, unit pile die is concrete by external mold, internal mold is concrete, internal mold fixed support, reinforcing cage fixed support, steel bar tensioning device forms, described external mold is specifically fixedly connected into the side template of both sides is mutually vertical by soffit formwork, its structure and the interconnected relationship between them same as the prior art, this does not repeat, it is circular mast or pipe that described internal mold is specially an external diameter cross section, described steel bar tensioning device is made up of detent mechanism and stretch-draw mechanism, detent mechanism is a fixture, stretch-draw mechanism can be mechanical type, also fluid pressure type can be adopted, its structure and the interconnected relationship between them same as the prior art, this does not repeat,
Step 2, make reinforcing cage, reinforcing cage is that the regular screw threads reinforcing bar of 0.1 σ-0.8 σ and terminal pad form by the prestressing force be parallel to each other, terminal pad is outer mold body section shape, central authorities are provided with the through hole of inner mold body diameter size, the two ends of regular screw threads reinforcing bar are connected with the two ends of terminal pad respectively, the regular screw threads reinforcing bar be parallel to each other in two terminal pads is welded by connecting reinforcement or ties up the reinforcing cage being made into tubular, the terminal pad of reinforcing cage one end is provided with the locating ring be connected with detent mechanism, the terminal pad of the other end of reinforcing cage is provided with the connecting ring be connected with stretch-draw mechanism, reinforcing cage is put into external mold concrete and located by reinforcing cage fixed support, reinforcing cage fixed support location adopts rod iron, one end of rod iron is specifically connected location with external mold, the other end is connected with the reinforcing bar on reinforcing cage, the initial stress that described regular screw threads reinforcing bar applies lower-prestressed is consistent, and the prestressing force of the stretch-draw of the regular screw threads reinforcing bar be parallel to each other in described unit stake is equal, identical with the moment of flexure making pile body produce when lifting by crane or transport, the overall performance of further raising pile body, the yield strength standard value of regular screw threads reinforcing bar is 300N/mm2-500N/mm2, lower-prestressed stretch-draw value is 0.1 σ-0.9 σ, by applying lower-prestressed stretch-draw to regular screw threads reinforcing bar, not only avoid pile body lift by crane and transport time cause by curved and produce crack, simultaneously, can also ensure in work progress the prestressing force abatement that the impact of pile body or time effect cause, significantly reduce the load of pressurized pile body,
Step 3, installation internal mold are concrete, internal mold is specifically positioned in the concrete interior reinforcing cage of external mold by internal mold fixed support, internal mold fixed support is also adopt rod iron, one end of rod iron is specifically connected location with external mold, the other end is connected with inner mold, and inner mold inserts from the main point of reinforcing cage, its technique and its structure and the interconnected relationship between them same as the prior art, this does not repeat
Step 4, to be exerted a force to terminal pad by steel bar tensioning device, carry out lower-prestressed stretch-draw to the regular screw threads reinforcing bar be parallel to each other of composition reinforcing cage, make that regular screw threads are prestressed, reinforced to be 0.1 σ-0.8 σ and to keep stretch-draw, optimum prestress is 0.3 ~ 0.6 σ,
Step 5, make antirust, that impermeability is strong concrete, concrete is made up of cement 15-25%, husky 25-40%, stone 35-65%, water reducing agent 0.01-1% and corrosion inhibitor 0.01-1%, and cement adopts strength grade to be not less than the sulfate resisting cement of 42.5 grades or portland cement, the Portland cement of treated (mixing Admixture or the mineral admixture of sulfate resistance); Fines should adopt clean natural hard medium coarse sand, and fineness modulus is preferably 2.8-3.1, and when adopting manufactured sand, fineness modulus can be 2.9-3.3; Coarse aggregate should adopt rubble, continuous grading, and flat-elongated particles is no more than 10%, and mud content should be not more than 1%, and maximum particle diameter should not be greater than 35mm, and should not exceed 3/4 of distance of reinforcing bar; For improving antiseptic property, mixing the Admixtures such as the high efficiency water reducing agent of 0.01-5%, sulfate resistance Admixture and reinforcing steel bar corrosion inhibitor, also can mix the mineral admixtures such as 0.01-20% silica flour or flyash,
Step 6, be coated with one deck interleaving agent at cast inner mold external surface, square outer mold inner surface, by the high performance concrete feeding mould for preparing and after hand punning or centrifugal dense concrete,
Step 7, when pile strength reaches 40 ~ 80%, unclamp steel bar tensioning device and dismantle mold, and according to design length, the terminal pad of unit mould through its end being weldingly connected into pile body,
Step 8, clean pile body terminal pad surface also brushing thickness are not less than the fiber reinforced resin layer of 0.5-2.5mm, and optimum thickness is less than 1.5mm, fiber reinforced resin layer is wound around again the carbon cloth that can improve antiseptic power and resistance to tension.
The yield strength value of plain bars of the present invention is 300N/mm 2-500N/mm 2plain bars, the two ends of plain bars are weldingly connected with terminal pad respectively.
High performance concrete of the present invention, while mobility needed for guarantee concrete batching system, reduces water supply volume as far as possible, and reduce water/binder ratio, make concrete total pore space, particularly capillary interstice rate significantly reduces.Cement, after the stirring that adds water, can produce a kind of flocculence structure.In these flocculence structures, be wrapped in many mixing waters, thus reduce the workability of green concrete.In order to keep the workability needed for concrete batching system in construction, just correspondingly must increase water supply volume when mixing and stirring, will impel in water mudrock structure forming too much hole like this.When adding aligning of water reducing agent, make cement particle surface all with identical charges.Under the effect of electrical repulsion, not only make cement system be in metastable suspended state, also form one deck solvation moisture film at cement particle surface, make the free water in Flocculated Cement body discharge simultaneously, thus reach the object of diminishing.Much research shows, when water/binder ratio is reduced to below 0.38, the target eliminating capillary interstice just can realize, and mixes high efficiency water reducing agent, water/binder ratio can be reduced to less than 0.38 completely.
The deficiency of hydrate stability in the Behavior of Hardened Cement Paste of ordinary concrete is that concrete can not another principal element of super-durable.In ordinary concrete, mix the object of active mineral, be to improve the composition of the gum material of Behavior of Hardened Cement Paste in concrete.Containing a large amount of active SiO in active mineral additives 2and active A l 2o 3their can and cement hydration process in the free lime that produces and high alkalinity aquation silicon acid calcium generation secondary response, generate the low alkalinity aquation silicon acid calcium that intensity is higher, stability is more excellent, thus reach the composition improving aquation gum material, eliminate the object of free lime, make water mudrock structure more fine and close, and block the infiltration road that may be formed.In addition, can also improve and gather materials and the interfacial structure of Behavior of Hardened Cement Paste and boundary zone performance.These important effects, have the contribution of internal to the concrete durability of enhancement and intensity.
The yield strength standard value of regular screw threads reinforcing bar of the present invention is 300N/mm2-500N/mm2, lower-prestressed stretch-draw value is 0.1 σ-0.9 σ, by applying lower-prestressed stretch-draw to regular screw threads reinforcing bar, not only avoid pile body lift by crane and transport time cause by curved and produce crack, simultaneously, can also ensure to cut down the prestressing force that the impact of pile body or time effect cause in work progress, significantly reduce the load of pressurized pile body.
The briny environments such as particularly suitable Yu Haiyang of the present invention, saline-alkali soil use.It is as follows that the present invention calculates checking:
The calculatingcrackswidth of 1 common non-prestressed precast square pile
1. designing the 400 ㎜ × 400 anticorrosive stakes of ㎜ specification BF type in atlas L13SG329 according to Shandong Province's building standard is example,
Square pile specification 400 ㎜ × 400 ㎜, Theoretical Mass ρ=400kg/m, the long L=15m of stake, at 0.207L and 3.1m place, positive hogging moment equal place suspension centre is for calculating bearing, strength grade of concrete C60, modulus of elasticity of concrete E c=3.6 × 10 4n/mm 2, tensile region reinforcing bar is 2C18, Steel Bar Tensile Strength design load f y=360N/mm 2, reinforcing bar elastic modulus E s=2 × 10 5n/mm 2, thickness of concrete cover c=55mm.
Effective tension area: A te=0.5bh=0.5 × 400 × 400=80000mm 2
Longitudinal tensile area of reinforcement: A s = 2 · 1 4 πd 2 = 2 × 1 4 × 3.14 × 18 2 = 509 mm 2
Longitudinal tensile rebar ratio: ρ t e = A s A t e = 509 80000 = 0.006
Moment of flexure: M q = 1 2 ρgl 2 = 1 2 × 400 × 9.8 × 10 - 3 × 3.1 2 = 18.8 k N · m
Longitudinal tensile reinforcement stresses: σ s q = M q 0.87 h 0 A s = 18.8 × 10 6 0.87 × ( 400 - 55 ) × 509 = 123.1 N / mm 2
Maximum crack: ω m a x = α c r ψ σ s E s ( 1.9 c + 0.08 d e q ρ t e )
= 1.9 × 0.2 × 123.1 2 × 10 5 × ( 1.9 × 55 + 0.08 × 18 0.006 ) = 0.081 m m
For anticorrosive stake, there is crack that the corrosive medium of outside will be made to enter, cause the destruction of pile body, so must not crack be had to anticorrosive stake.
2. high-performance lower-prestressed concrete hollow square pile crack resisting calculation
Stake section area: A = 400 × 400 - 1 4 × π × 144 2 = 143722 mm 2
Stake cross section bending resistance resistance moment: W = bh 2 6 - πd 3 32 = 400 3 6 - π × 144 3 32 = 10.37 × 10 6 mm 3
Moment of flexure: M q = 1 2 ρgl 2 = 1 2 × 400 × 9.8 × 10 - 3 × 3.1 2 = 18.8 k N · m
The tensile stress that concrete lower limb produces: σ c k = M k W = 18.8 × 10 6 10.37 × 10 6 = 1.81 N / mm 2
Longitudinal tensile area of reinforcement: A s = 2 · 1 4 πd 2 = 2 × 1 4 × 3.14 × 18 2 = 509 mm 2
By the prestressing force (deducting the actual value after loss of prestress) of 30% stretch-draw, concrete normal force
N x=30%·A s×σ k=30%×509×2×360=109944N
The compressive pre-stress that concrete lower limb produces
σ p c = N x A = 109944 143722 = 0.76 N / mm 2
Cracking resistance stress σ ckpc=1.81-0.76=1.05≤f tk=2.85N/mm 2
Experience meets the requirements, and there will not be crack.
2 mix high efficiency water reducing agent, improve concrete impervious ability, delay concrete erosion, while mobility, reduce water supply volume as far as possible, reduce water/binder ratio needed for guarantee concrete batching system, make concrete total pore space particularly capillary interstice rate significantly reduce.Cement, after the stirring that adds water, can produce a kind of flocculence structure, be wrapped in many mixing waters, thus reduce the workability of green concrete in these flocculence structures.In order to ensure the workability of concrete batching system in construction, just must increase water supply volume when stirring, will impel in water mudrock structure like this and forming too much hole.When adding aligning of water reducing agent, make cement particle surface all with identical charges.Under the effect of electrical repulsion, not only make cement system be in metastable suspended state, also form one deck solvation moisture film at cement particle surface, make the free water in Flocculated Cement body discharge simultaneously, thus reach the object of diminishing.Much research shows, when water/binder ratio is reduced to below 0.38, the target eliminating capillary interstice just can realize, and mixes high efficiency water reducing agent, water/binder ratio can be reduced to less than 0.38 completely.
3 mix mineral admixture (silica flour or flyash), improve concrete impermeability and intensity, mix mineral admixture (silica flour or flyash), fully play the effect of micro-aggregate, rational gradation composition is carried out to concrete mix, make to gather materials from slightly, thin to micro-, ensure that concrete compactness, improve concrete impermeability and intensity, the calcium hydroxide generated in silica simultaneously in admixture and cement hydration process carries out secondary response and forms hydrated calcium silicate gel, make concrete in Sulfates erosion medium resistance, expansion crystallographic can not be formed with the calcium oxide in concrete, prevent the erosion damage of sulfate species.
4 butt joints place and pile top place carry out anti-corrosion protection, in, strong corrosive environment, the joint end plate of square pile and the exposed steel bar at pile top place must carry out protective treatment.When square pile appears on the scene, epoxy coating can be carried out for exposed steel bar part; For tip side plate portion, moderate corrosion end plate can brush fast-set resin, and deep-etching header portion can brush fast-set resin paste carbon cloth, so not only ensure that antiseptic property but also can improve the tensile strength of precast square pile end plate joint.
Advantageous effect of the present invention is:
(1) compared with hollow shell pill, concrete corrosion allowance can be increased; Compared with castinplace pile, it does not contact with corrosive substance in formation of pile; (2) compared with pile tube, when volume of concrete is identical, the surface area of square pile is larger, significantly can improve bearing capacity of friction pile; (3) high-performance lower-prestressed concrete hollow square pile adopts hollow-core construction process, and save raw material, cost of production reduces greatly, meets green construction requirement; (4) protection at terminal pad place and the size of Shi Hanzhang etc. are through appropriate design, the resistance to corrosion of concrete hollow square pile is improved greatly, can meet the life requirement of moderate corrosion and general deep-etching completely; (5) adopt hollow concrete prefabricated in the above scope of high-performance lower-prestressed concrete hollow square pile pile top 2m, ensure that pile body integrity when square pile is constructed.Pile foundation construction need pass through there is more boulder and obstruction in thicker harder interlayer or place time, often a kind of illusion of piling can be seen: after the pile concrete near the pile top of a pile is broken, the above pile concrete in broken place continuously destroys along with top impact pile driving, outwardly, the hammering downward injection of pile body once a bit, these hammering energies are all for destroying bottom shaft concrete and being expressed in the soil layer of surrounding by its fragment in fact, and piling embedded depth is only an illusion.Can effectively solve piling artefact problems by doing hollow process within the scope of pile top 2 meters, ensure that the integrality of pile body during construction, also effectively improve the bearing capacity of pile body simultaneously; (6) high-performance lower-prestressed concrete hollow square pile bearing capacity of pile than square pile of the same type and pile tube higher; Because pile body position is identical with the structure of pile tube, be all hollow, external overall shape or square, therefore pile body external surface area is than pile tube larger of identical caliber, and improving bearing capacity for friction pile has significant impact.This high-performance lower-prestressed concrete hollow square pile has the advantage of square pile and pile tube concurrently simultaneously, and bearing capacity is relatively higher; (7) high-performance lower-prestressed concrete hollow square pile weight is lighter, production and transport is convenient, more not easily crack is produced during construction, this square pile adopts hollow-core construction process, compare square pile weight of the same type lighter, crack can not be produced owing to mutually colliding during production and transport, also not easily produce broken pile during site operation, pile concrete falls the phenomenons such as block; (8) high-performance lower-prestressed concrete hollow square pile pile concrete is more closely knit, more can ensure integrality, the compactness of pile body, because square pile adopts the hollow-core construction identical with pile tube, therefore centrifugal process can be adopted to produce in production square pile flow process, but not the artificial vibrated concrete of plain hollow square pile, significantly improve the compactness of pile concrete, bearing capacity of pile improves greatly; (9) high-performance lower-prestressed concrete hollow square pile adopts hollow-core construction process, save raw material, cost of production reduces greatly, meet green construction " material-saving and material resources utilize technology " and builing industry New technical use " concrete technology ", construction work green construction " material-saving and material resources utilize technical essential " comprises " promote the use of high performance concrete, reduce resource consumption ".Builing industry New technical use " concrete technology " comprises " high durability concrete, high-strength high-performance concrete ".This square pile adopts strong concrete, the multiple high performance additive of admixture, improves multiple index such as impermeability, intensity of pile concrete.Also more save raw material when hollow-core construction is produced, effectively reduce cost of production; (10) safety and the durability of pile foundation is met, after the construction of high-performance lower-prestressed concrete hollow square pile, the prefabricated filling core block shutoff of pile crown, has completely cut off the hazardous substancess such as extraneous aggressivity and has entered the inner accelerate concrete corrosion of pile body, met safety and the durability of pile foundation.

Claims (6)

1. a high-performance lower-prestressed concrete hollow square pile, comprise pile body, pile crown, the stake of at least one joint unit of pile body forms, it is characterized in that unit stake cross section is that central authorities establish round-meshed side's shape shape, the reinforcing bar that the pile lining of unit stake is 0.1 σ-0.8 σ by the prestressing force be parallel to each other in concrete and concrete forms, the two ends of unit stake are respectively equipped with terminal pad, the two ends of reinforcing bar are connected with terminal pad respectively, adjacent cells stake forms pile body through terminal pad welding, the fibre resin of the two terminal pads outer brushing thickness 0.5-2.5mm be connected, fiber reinforced resin layer is wound around again the carbon cloth that can improve antiseptic power and resistance to tension, its production technology is as follows:
Step one, production unit pile die, unit pile die is concrete by external mold, internal mold concrete, internal mold fixed support, reinforcing cage fixed support, steel bar tensioning device form, described external mold is specifically fixedly connected into the side template of both sides is mutually vertical by soffit formwork, it is circular mast or pipe that described internal mold is specially an external diameter cross section, described steel bar tensioning device is made up of detent mechanism and stretch-draw mechanism
Step 2, make reinforcing cage, reinforcing cage is that the regular screw threads reinforcing bar of 0.1 σ-0.8 σ and terminal pad form by the prestressing force be parallel to each other, terminal pad is outer mold body section shape, central authorities are provided with the through hole of inner mold body diameter size, the two ends of regular screw threads reinforcing bar are connected with the two ends of terminal pad respectively, the regular screw threads reinforcing bar be parallel to each other in two terminal pads is welded by connecting reinforcement or ties up the reinforcing cage being made into tubular, the terminal pad of reinforcing cage one end is provided with the locating ring be connected with detent mechanism, the terminal pad of the other end of reinforcing cage is provided with the connecting ring be connected with stretch-draw mechanism, reinforcing cage is put into external mold concrete and located by reinforcing cage fixed support,
Step 3, installation internal mold are concrete, are specifically positioned in the concrete interior reinforcing cage of external mold by internal mold fixed support by internal mold,
Step 4, by steel bar tensioning device, terminal pad to be exerted a force, lower-prestressed stretch-draw is carried out to the regular screw threads reinforcing bar be parallel to each other of composition reinforcing cage, make that regular screw threads are prestressed, reinforced to be 0.1 σ-0.8 σ and to keep stretch-draw,
Step 5, make antirust, that impermeability is strong concrete, concrete is made up of cement 15-25%, husky 25-40%, stone 35-65%, water reducing agent 0.01-1% and corrosion inhibitor 0.01-1%, and cement adopts strength grade to be not less than the sulfate resisting cement of 42.5 grades or portland cement, the Portland cement of treated (mixing Admixture or the mineral admixture of sulfate resistance); Fines should adopt clean natural hard medium coarse sand, and fineness modulus is preferably 2.8-3.1, and when adopting manufactured sand, fineness modulus can be 2.9-3.3; Coarse aggregate should adopt rubble, continuous grading, and flat-elongated particles is no more than 10%, and mud content should be not more than 1%, and maximum particle diameter should not be greater than 35mm, and should not exceed 3/4 of distance of reinforcing bar; For improving antiseptic property, mixing the Admixtures such as the high efficiency water reducing agent of 0.01-5%, sulfate resistance Admixture and reinforcing steel bar corrosion inhibitor, also can mix the mineral admixtures such as 0.01-20% silica flour or flyash.
2. step 6, be coated with one deck interleaving agent at cast inner mold external surface, square outer mold inner surface, by the high performance concrete feeding mould for preparing and after hand punning or centrifugal dense concrete,
Step 7, when pile strength reaches 40 ~ 80%, unclamp steel bar tensioning device and dismantle mold, and according to design length, the terminal pad of unit mould through its end being weldingly connected into pile body,
Step 8, clean pile body terminal pad surface also brushing thickness are not less than the fiber reinforced resin layer of 0.5-2.5mm, and optimum thickness is less than 1.5mm, fiber reinforced resin layer is wound around again the carbon cloth that can improve antiseptic power and resistance to tension.
3. a kind of high-performance lower-prestressed concrete hollow square pile according to claim 1, is characterized in that the optimum prestress that step 4 plain bars first carries out stretch processing is 0.3 ~ 0.6 σ.
4. a kind of high-performance lower-prestressed concrete hollow square pile according to claim 1, is characterized in that diameter is that the two ends of the plain bars of 12-50mm are weldingly connected with terminal pad respectively.
5. a kind of high-performance lower-prestressed concrete hollow square pile according to claim 1, is characterized in that concrete water/binder ratio is not more than 0.38:1.
6. a kind of high-performance lower-prestressed concrete hollow square pile according to claim 1, is characterized in that in concrete containing a large amount of active SiO 2and active A l 2o 3, the free lime produced in they and cement hydration process and high alkalinity aquation silicon acid calcium produce secondary response, generate the low alkalinity aquation silicon acid calcium of high strength, high stability, improve the composition of aquation gum material, eliminate the object of free lime.
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CN110642580A (en) * 2019-11-13 2020-01-03 南通海华建材有限公司 Preparation process of high-strength hollow square pile
CN111571775A (en) * 2020-04-30 2020-08-25 中铁上海工程局集团有限公司 Assembled hollow pier body and construction device and construction method thereof
CN114277788A (en) * 2021-12-06 2022-04-05 东南大学 Super-large diameter combined pile for offshore wind power

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