CN105821832A - Self-healing concrete pile preventing frost heaving and bonding weakening - Google Patents

Abstract

The invention discloses a self-healing concrete pile preventing frost heaving and bonding weakening. In order to improve the bonding performance between steel bars and concrete, a steel capsule string formed by connecting steel capsules through strip-shaped polypropylene fabrics in series is twined on each steel bar. By adopting the self-healing concrete pile, the tensile strength and shear strength of concrete can be remarkably improved, roughness of the concrete can be greatly enhanced, and accordingly the anti-seismic performance of the concrete is improved. The critical bonding stress between the steel bars and the concrete can be remarkably increased. As polypropylene has good plasticity, roughness and temperature adaptability, the polypropylene can have extremely strong resisting capacity on heaving stripping and degradation between the steel bars and the concrete in the freezing-thawing process. Because the positions and orientations of the steel capsules are distributed randomly in the concrete, the steel capsules can break to conduct repairing and heeling on cracks in all directions. Self-compacting concrete is adopted as the concrete in the pile, and accordingly the steel capsules in the concrete can be prevented from breaking during vibrating.

Description

The self union concrete stake that a kind of anti-lifting by frost bonding weakens

Technical field

The invention belongs to anti-lifting by frost and destroy technical field, the self union concrete stake that a kind of anti-lifting by frost bonding weakens.

Background technology

At cold district, the dilatancy produced due to freezing soil is limited by pile foundation, therefore will be produced tangent coordinate system on pile foundation surface.Along with the increasing of the active layer depth of freezing in season, the tangent coordinate system in stake week can become larger.When the degree of depth of pile foundation embedment is relatively deep or uses club-footed pile, under the effect of tangent coordinate system, concrete cracking, the reinforcing bar within pile foundation produces bond-slip with concrete.

At present, the main method used is to change in stake side to fill out non-frost heave material, typically uses the non-frost heave coarse particulate material such as coarse sand, cobble, slag.But, this method can produce disturbance to the soil body, affects the stability of pile foundation.

Another kind of method is to arrange insulating in stake side or bury heating wire underground and keep soil temperature to alleviate freezing soil degree, is frozen by minimizing and deeply reduces tangent coordinate system.Due to this method construction complexity, relatively costly, application is greatly restricted, and angle of operating from for a long time, is not a kind of economic and practical and durable pile foundation.

Still an alternative is that the size reducing stake cross section or the diameter increasing reinforcing bar.The size reducing stake cross section can reduce the tangent coordinate system in stake week, and the diameter increasing reinforcing bar can increase the critical bond stress of reinforcing bar and concrete.But the size reducing stake cross section can reduce the critical bearing capacity of stake；The diameter increasing reinforcing bar improves cost, and it is possible to the situation of overreinforced occur；Therefore, this method is the most impracticable.

More it is worth noting, said method does not all account in frozen-thaw process, mechanical property difference bigger between concrete and rebar is the most notable, show the deterioration of adhesive property between concrete and rebar during lifting by frost, coming off between the two even occur, the long-term operation to pile foundation is the most severe potential hazard.

Summary of the invention

In order to solve above-mentioned technical problem, the invention provides the self union concrete stake that a kind of anti-lifting by frost bonding weakens.

The technical solution adopted in the present invention is: the self union concrete stake that a kind of anti-lifting by frost bonding weakens, it is characterised in that: during concrete-agitating, put into steel capsule, to be mixed uniformly after pour in cut-and-dried concrete-pile model；Simultaneously in order to improve the adhesive property between steel and concrete, reinforcing bar is wound around the steel capsule string being cascaded by strip polypropylene fabric.

As preferably, described steel capsule is made up of steel capsule wall, structure glue, ring-shaped pottery；Being filled with structure glue inside described steel capsule wall, described ring-shaped pottery is arranged on the middle part of described steel capsule.

As preferably, described steel capsule wall is made by low-temperature high-toughness high strength steel, and thickness is 1～2mm；The wall thickness of described ring-shaped pottery is 0.2～0.3mm, and height is 2～2.5mm, and internal diameter, as the internal diameter size of steel capsule wall, is arranged in described steel capsule wall central slot.

As preferably, described steel capsule wall surface configuration has stereo concave-convex decorative pattern.

As preferably, a length of the 18～23mm of described steel capsule, a diameter of 5～8mm, volume volume is 10～15%.

As preferably, described strip polypropylene fabric is formed by monfil braiding, thickness 0.1mm, and width is 2～4mm, and the density being wrapped on reinforcing bar is 35～40 steel capsules of series connection in 1m length range.

As preferably, described concrete uses self-compacting concrete, is avoided that rupturing of steel capsule during vibrating.

As preferably, the volume volume ρ of described steel capsule_fComputing formula be:

${\mathrm{\ρ}}_f=\frac{f_{ft}{d}_f}{{\mathrm{\α}}_t{f}_t{l}_f}$

In formula, f_ftPreparation tensile strength for steel capsule concrete；f_tFor original concrete tensile strength, l_f/d_fDraw ratio for steel capsule；α_tFor empirical coefficient.

The invention have the advantage that

1, it is low-temperature high-toughness high strength steel due to the material of steel capsule wall, tension and the shearing strength of concrete can not only be significantly improved after mixing concrete, and the toughness of concrete can be greatly enhanced, and then improve its anti-seismic performance.Owing to the surface configuration of steel capsule wall has stereo concave-convex decorative pattern, the binding ability of capsule self and concrete after mixing concrete, can be strengthened.Owing to the pottery in the middle part of steel capsule is fragile material, thickness is suitable, can be the most damaged, and internal structure colloid flows out mended crack immediately.Ceramic material self performance is stable, good to thermal adaptability, will not because of in concrete the heat of hydration of cement and melted in advance lost efficacy.

2, it is wound with steel capsule string on reinforcing bar, is equivalent to the contact area increasing reinforcing bar with concrete, can significantly improve the adhesive property of reinforcing bar and concrete.Owing to strip polypropylene fabric intensity is high, good toughness, preferable binding ability is all had with concrete and reinforcing bar, can significantly increase the critical bond stress of reinforcing bar and concrete, due to the good plasticity of polypropylene self and toughness and the adaptability to temperature, the lifting by frost between reinforcing bar and concrete can be peeled off in frozen-thaw process and deterioration have extremely strong resistivity.

3, due to steel capsule position in concrete and orientation random distribution, then the crack of all directions has steel capsules break that it is carried out healing.Owing to the concrete in stake uses self-compacting concrete, the steel capsule in concrete can be avoided to rupture during vibrating.

Accompanying drawing explanation

Fig. 1 be the embodiment of the present invention stake cross section in the scattergram of steel capsule；

Fig. 2 is the steel capsule string of embodiment of the present invention scattergram on reinforcing bar；

Fig. 3 is the strip polypropylene fabric schematic diagram of the embodiment of the present invention；

Fig. 4 is the steel capsule attachment structure figure with strip polypropylene fabric of the embodiment of the present invention；

Fig. 5 is the structure chart of the steel capsule of the embodiment of the present invention；

Fig. 6 is the steel capsule wall cross section along a-a of the embodiment of the present invention；

Fig. 7 is the ring-shaped pottery relative location drawing with steel capsule wall of the embodiment of the present invention.

Detailed description of the invention

Understand for the ease of those of ordinary skill in the art and implement the present invention, below in conjunction with the accompanying drawings and embodiment the present invention is described in further detail, should be appreciated that enforcement example described herein is merely to illustrate and explains the present invention, be not intended to limit the present invention.

Ask for an interview Fig. 1-Fig. 7, the self union concrete stake that a kind of anti-lifting by frost bonding that the present invention provides weakens, during concrete 2 stirs, put into steel capsule 1, to be mixed uniformly after pour in cut-and-dried concrete-pile model；Simultaneously in order to improve the adhesive property between reinforcing bar 3 and concrete 2, reinforcing bar 3 is wound around the steel capsule 1 being cascaded by strip polypropylene fabric 4 and goes here and there.

When the tangent coordinate system acting on pile foundation surface is sufficiently large, the local of pile body will be pulled off, and i.e. concrete 2 ftractures and between reinforcing bar 3 and concrete 2, bond stress deterioration is even lost and produced sliding.In order to improve the adhesive property between reinforcing bar 3 and concrete 2, reinforcing bar 2 is wound around steel capsule string.The thickness (t) of strip polypropylene fabric 5 and width (b) can not be too big, simultaneously can not be the least, otherwise to improving adhesive property without remarkable result.To sum up, strip polypropylene fabric 5 is formed by monfil braiding, thickness 0.1mm, and width is 2～4mm, is wrapped in 35～40 steel capsules 1 of series connection in the about 1m length range of the density on reinforcing bar 3.

The steel capsule 1 of the present embodiment is made up of steel capsule wall 5, structure glue 6, ring-shaped pottery 7；Steel capsule wall 5 is internal is filled with structure glue 6, and ring-shaped pottery 7 is arranged on the middle part of steel capsule 1.In order to ensure that steel capsule 1 has certain rigidity, and can improve its intensity and toughness after mixing concrete, the material of steel capsule wall 5 uses low-temperature high-toughness high strength steel, and thickness is taken as 1～2mm.In order to make steel capsule 1 can rupture in time after concrete produces crack, the wall thickness of ring-shaped pottery 7 is 0.2～0.3mm, and height is 2～2.5mm, and internal diameter, as the internal diameter size of steel capsule wall 6, is arranged in steel capsule wall 5 central slot.In order to improve the adhesive property of steel capsule 1 and concrete 2, there is stereo concave-convex decorative pattern 8 in its surface configuration.In order to the distress in concrete after ensureing healing no longer ftractures, after the reparation adhesive of steel capsule must have higher adhesion strength, and adhesive solidification, intensity own is good, therefore repairs adhesive and use structure glue 6.

Length (the l of steel capsule 1_f) and diameter (d_f) can not be the least, otherwise its internal volume is too small, will affect its healing properties；But can not be too big, because oversize being not only difficult to of steel capsule 1 is uniformly dispersed in concrete, and can be easily broken in whipping process, affect the performance of steel capsule 1 effect.The length of the steel capsule 1 of the present embodiment is taken as 18～23mm, and a diameter of 5～8mm, volume volume is 10～15%.

The concrete 2 of the present embodiment uses self-compacting concrete, and during can avoiding vibrating, steel capsule 1 ruptures.Owing to the comprcssive strength of concrete 2 is affected bigger by the ratio of mud and strength of cement grade；The tensile strength of concrete 2 is affected bigger by the volume fraction of steel capsule 1 and draw ratio, strength of cement grade；The workability of concrete 2 is affected bigger by sand coarse aggregate ratio and water consumption.So, determine the ratio of mud with comprcssive strength and the ratio of mud, the relation of strength of cement；Steel capsule volume fraction is determined with tensile strength and the ratio of mud, the relation of steel capsule volume fraction；Then determine sand coarse aggregate ratio and water consumption according to the requirement of workability, obtain calculating match ratio, be adjusted finally according to execution conditions, obtain coordination in works.

The design process of the mix parameters of high-strength self-compacting concrete of the present embodiment is as follows:

(1) first press Structural strength calls and select cement, by actual cement strength f_cePoor with statistical standard determine preparation strength f_fcu.Then according to preparation strength f_fcuWith ratio of mud W/C, actual cement strength f_ceRelation determine the ratio of mud.Owing to the existing empirical equation of the relation between them is: f_fcu=α₁f_ce(C/W-β₁), then the computing formula of the ratio of mud is as follows:

$W/C=\frac{{\mathrm{\α}}_1{f}_{ce}}{f_{fcu}+{\mathrm{\α}}_1{\mathrm{\β}}_1{f}_{ce}}$

In formula, α₁And β₁For empirical coefficient, α₁=0.46, β₁=0.07.

(2) preparation tensile strength f of steel capsule concrete is utilized_ftWith original concrete tensile strength f_t, the volume fraction ρ of steel capsule_f, draw ratio l_f/d_fRelation determine the volume volume of steel capsule.Due to preparation tensile strength f_ftAlong with original concrete tensile strength f_t, the volume volume ρ of steel capsule_fWith draw ratio l_f/d_fIncrease and increase, therefore suppose that their relation is:

f_ft=α_tf_tρ_fl_f/d_f

Then the volume volume of steel capsule is:

${\mathrm{\ρ}}_f=\frac{f_{ft}{d}_f}{{\mathrm{\α}}_t{f}_t{l}_f}$

In formula, α_tFor empirical coefficient, α_t=0.45.

(3) after primarily determining that the volume volume of the ratio of mud and steel capsule, determine sand coarse aggregate ratio and water consumption according to the requirement of workability, obtain calculating match ratio.

(4) on the basis of calculating match ratio, by testing and combine the condition Adjustable calculation match ratio of job site, final coordination in works is obtained.

The present embodiment, during concrete 2 stirs, puts into steel capsule 1, to be mixed uniformly after, then the steel capsule 1 position distribution in concrete 2 is uniform, and the orientation of steel capsule 1 is then random.

Although this specification more employs the terms such as steel capsule 1, self-compacting concrete 2, reinforcing bar 3, strip polypropylene fabric 4, steel capsule wall 5, structure glue 6, ring-shaped pottery 7 and stereo concave-convex decorative pattern 8, but is not precluded from using the probability of other terms.Using these terms to be only used to more easily to describe the essence of the present invention, it is all contrary with spirit of the present invention for being construed as any additional restriction.

It should be appreciated that the part that this specification does not elaborates belongs to prior art.

Should be understood that; the above-mentioned description for preferred embodiment is the most detailed; therefore the restriction to scope of patent protection of the present invention can not be considered; those of ordinary skill in the art is under the enlightenment of the present invention; under the ambit protected without departing from the claims in the present invention; can also make replacement or deformation, within each falling within protection scope of the present invention, the scope that is claimed of the present invention should be as the criterion with claims.

Claims (8)

1. the self union concrete stake that anti-lifting by frost bonding weakens, it is characterised in that: during concrete (2) stirs, put into steel capsule (1), to be mixed uniformly after pour in cut-and-dried concrete-pile model；Simultaneously in order to improve the adhesive property between reinforcing bar (3) and concrete (2), go here and there at the upper steel capsule (1) being cascaded by strip polypropylene fabric (4) that is wound around of reinforcing bar (3).

The self union concrete stake that anti-lifting by frost the most according to claim 1 bonding weakens, it is characterised in that: described steel capsule (1) is made up of steel capsule wall (5), structure glue (6), ring-shaped pottery (7)；Described steel capsule wall (5) is internal is filled with structure glue (6), and described ring-shaped pottery (7) is arranged on the middle part of described steel capsule (1).

The self union concrete stake that anti-lifting by frost the most according to claim 2 bonding weakens, it is characterised in that: described steel capsule wall (5) is made by low-temperature high-toughness high strength steel, and thickness is 1～2mm；The wall thickness of described ring-shaped pottery (6) is 0.2～0.3mm, and height is 2～2.5mm, and internal diameter, as the internal diameter size of steel capsule wall (5), is arranged in described steel capsule wall (5) central slot.

4. the self union concrete stake weakened according to the anti-lifting by frost bonding described in Claims 2 or 3, it is characterised in that: described steel capsule wall (5) surface configuration has stereo concave-convex decorative pattern (8).

The self union concrete stake that anti-lifting by frost the most according to claim 1 bonding weakens, it is characterised in that: a length of the 18～23mm of described steel capsule (1), a diameter of 5～8mm, volume volume is 10～15%.

The self union concrete stake that anti-lifting by frost the most according to claim 1 bonding weakens, it is characterized in that: described strip polypropylene fabric (4) is formed by monfil braiding, thickness 0.1mm, width is 2～4mm, and the density being wrapped on reinforcing bar is 35～40 steel capsules (1) of series connection in 1m length range.

The self union concrete stake that anti-lifting by frost the most according to claim 1 bonding weakens, it is characterised in that: described concrete (2) uses self-compacting concrete, is avoided that rupturing of steel capsule (1) during vibrating.

8. the self union concrete stake weakened according to the anti-lifting by frost bonding described in claim 1,2,3,5,6 or 7, it is characterised in that: the volume volume ρ of described steel capsule (1)_fComputing formula be:

${\mathrm{\ρ}}_f=\frac{f_{ft}{d}_f}{{\mathrm{\α}}_t{f}_t{l}_f}$

In formula, f_ftPreparation tensile strength for steel capsule concrete；f_tFor original concrete tensile strength, l_f/d_fDraw ratio for steel capsule；α_tFor empirical coefficient.