CN117683329A - Super-strength, high-fatigue-resistance and high-temperature-resistance stay cable cold-cast anchor grouting material and anchor grouting method - Google Patents
Super-strength, high-fatigue-resistance and high-temperature-resistance stay cable cold-cast anchor grouting material and anchor grouting method Download PDFInfo
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- CN117683329A CN117683329A CN202311541253.5A CN202311541253A CN117683329A CN 117683329 A CN117683329 A CN 117683329A CN 202311541253 A CN202311541253 A CN 202311541253A CN 117683329 A CN117683329 A CN 117683329A
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- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 7
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Abstract
The invention relates to an ultra-high strength, high fatigue resistance and high temperature resistance stay cable cold casting and anchoring material and an anchoring and grouting method, and belongs to the field of cable-stayed bridge anchoring. The cold casting anchor filling material comprises steel balls, bisphenol A diglycidyl ether resin, a curing agent, a fireproof filling filler and a toughening agent; the steel balls comprise steel balls with more than two diameters, the bonding strength fe of the bisphenol A diglycidyl ether resin after curing is more than 80MPa, and the compactness v of the steel balls is more than 53%. The steel ball consists of a first-stage steel ball and a second-stage steel ball, and the diameter D of the first-stage steel ball 1 Diameter D of the secondary steel ball is 1-2mm 2 Diameter D smaller than the first-stage steel ball 1 The secondary steel ball is filled in the primary steelIn the stacking gap of the balls. The compressive strength of the cold casting body obtained by the method can reach 170 MPa-230 MPa, and the anchoring requirement of the ultra-high strength and high fatigue resistance stay cable with the phi of 7mm-2100MPa is met.
Description
Technical Field
The invention relates to an anchor grouting material of a stay cable anchor and an anchor grouting method.
Background
Along with the improvement of the strength of the stay cable steel wire and the enlargement of the stay cable specification, the bearing capacity of a single stay cable is continuously improved. The traditional stay cable cold-cast anchor-filling material has lower strength, generally has compressive strength not lower than 147MPa and poor fireproof performance, can not meet the anchoring requirements of the stay cable with ultra-high strength and high fatigue resistance of phi 7mm-2100MPa, and needs to develop a novel cold-cast anchor-filling material and an anchor-filling method aiming at the stay cable with ultra-high strength and high fatigue resistance of phi 7mm-2100MPa so as to realize the anchor matching property of the stay cable with ultra-high strength, high fatigue resistance and large specification.
Disclosure of Invention
The invention aims to provide an ultra-high strength and high fatigue resistance stay cable cold casting anchor material, and the compressive strength is more than 170 MPa.
Another object of the present invention is to provide a method for casting an anchor material to optimize the way the anchor material is cast, thereby achieving better compactness.
The specific technical scheme of the invention is as follows: an ultra-high strength, high anti-fatigue and high temperature resistant stay cable cold casting anchor irrigation material is characterized in that: comprises steel balls, bisphenol A diglycidyl ether resin, curing agent, fire-resistant filling filler and toughening agent; the steel balls comprise steel balls with more than two diameters, the bonding strength fe of the bisphenol A diglycidyl ether resin after curing is more than 80MPa, and the compactness v of the steel balls is more than 53%.
As one of the preferable modes of the application, the steel ballConsists of a first-stage steel ball and a second-stage steel ball, wherein the diameter D of the first-stage steel ball 1 Diameter D of the secondary steel ball is 1-2mm 2 Diameter D smaller than the first-stage steel ball 1 The second steel balls are filled in the stacking gaps of the first steel balls.
As one of the preferred modes of the present application, for large-size anchors: the inner diameter of the anchorage device is larger than 250mm, the first-stage steel balls simulate quadrilateral stacking, small steel balls are embedded in gaps among the first-stage steel balls, and the diameter D of the second-stage steel balls is set 2 ＝0.41D 1 The steel ball compactness v=55.69% corresponding to this stacking mode.
As one of the preferred modes of the present application, for small-gauge anchors: the inner diameter of the anchorage device is less than or equal to 250mm, the primary steel balls simulate triangle stacking, small steel balls are embedded in gaps between the primary steel balls, and the diameter D of the secondary steel balls is set 2 ＝0.15D 1 The steel ball compactness v=60% corresponding to this stacking mode.
As one of the preferable modes of the application, for small-specification anchorage devices, the diameter D of the primary steel ball 1d The value range is 0.8-1.8mm, D 2 The range of the value of (C) is 0.12-0.24mm.
As one preferable mode of the application, the hardness of the steel ball is HRC 60-70.
As one of the preferred modes of the application, EP01441 epoxy resin with 184-195 g/mol of epoxy equivalent and EP01451 epoxy resin with 210-230 g/mol of epoxy equivalent are mixed according to the mass ratio of (4:6) to (6:4), and the obtained mixed epoxy resin has bonding strength not lower than 20MPa and compressive strength not lower than 80MPa.
Further, the curing agent in the cold casting anchor wiping material is one of a phenolic amine type small molecule curing agent and an anhydride type curing agent, and the dosage of the anhydride type curing agent is 0.85 time of the weight of the bisphenol A type diglycidyl ether resin.
Further, the refractory filling filler in the cold casting anchor wiping material is alumina and quartz powder, the volume usage of the alumina is 10-30% of the volume usage of bisphenol A diglycidyl ether resin, and the fineness of the quartz powder is as follows: 80% or more of the particles smaller than 1 μm have an average particle diameter of: 0.1-0.3 mu m, melting point: 1650 ℃, relative density: 2.65, the volume consumption of the quartz powder is 10-20% of the volume consumption of the bisphenol A diglycidyl ether resin;
further, the toughening agent in the cold casting anchor wiper is selected from one or more of dibutyl phthalate, dioctyl phthalate and tricresyl phosphate, and the dosage of the toughening agent is 2-10% of the weight of the bisphenol A diglycidyl ether resin.
Another object of the present application is to provide an anchor pouring method for an optimized cold cast anchor pouring material, wherein the anchor pouring material is uniformly mixed and stirred to obtain a liquefied cold cast anchor pouring material, a vibrator is mounted on the anchor, vibration energy of the vibrator is transmitted to the cold cast anchor pouring material through the anchor during anchor pouring, the vibration amplitude of the vibrator is between 0.5mm and 3.0mm, and the vibration frequency is between 50Hz and 300 Hz.
Preferably, when the diameter and the length of the anchor are larger than 250mm, the vibrators are arranged at both sides of the anchor to vibrate simultaneously, one vibrator is arranged every 250mm, after the cold cast anchor pouring material is poured into the anchor, the vibrator is started to vibrate, the pouring height of the cold cast anchor pouring material is higher than the mounting position of the vibrator, and when the gap between the steel wire is smaller or the gap between the steel wire and the anchor is deeper and narrower, a method of pouring and vibrating simultaneously is adopted; the external vibrator is tightly connected with the anchor, and the vibration time is based on the condition that no bubbles appear in the cold casting anchor pouring material and the surface is horizontal.
Compared with the prior art, the invention has the advantages that:
the compressive strength of the cold casting body obtained by the method can reach 170MPa to 230MPa.
The stay cable adopting the cold casting filler (cold casting anchor filling material) has the tensile strength of the stay cable with the upper stress limit of 40 percent, high stress amplitude of 280MPa and 200 ten thousand fatigue cycles, and the anchor does not fail.
In addition, the stay cable anchor head adopting the heat-resistant type cold casting filler is loaded for 30 minutes according to 40% stay cable breaking load under the action of 300 ℃ and the anchoring is not invalid.
Drawings
FIG. 1 is a schematic diagram of a stay cable chill casting anchor structure;
FIG. 2 is a schematic diagram of a chilled filler steel ball arrangement stacked in a quadrilateral manner;
FIG. 3 is a schematic diagram of a triangular stacked chilled filler steel ball arrangement;
FIG. 4 is a diagram of a mechanical stirring device for cold casting anchor materials;
FIG. 5 is a construction block diagram of an anchor casting filler in accordance with an embodiment of the present invention;
in the figure, an anchor cover plate 1, a steel wire upsetting head 2, an anchor cup 3, a nut 4, an anchor cup tensioning thread 5, an anchor plate 6, a cold casting and grouting anchor material 7, a cold casting and grouting anchor material 8, a cold casting and grouting anchor material 2, a cold casting and grouting anchor material 9, a stirring cylinder 10, a stirring blade 11, a discharge port 12, a vibrator 13 and a steel wire bundle 14.
Detailed Description
The present invention is described in further detail below with reference to the accompanying drawings, which are exemplary and intended to be illustrative of the invention and not to be construed as limiting the invention. The text description in the embodiment corresponds to the drawings, the description related to the orientation is also based on the drawings, and the description is not to be construed as limiting the protection scope of the invention.
The super-strength, high-fatigue-resistance and high-temperature-resistance stay cable chill casting filler provided by the embodiment is composed of steel balls with different diameters, high-strength bisphenol A diglycidyl ether resin, a curing agent, a fireproof filling filler, a toughening agent and the like.
After extrusion molding and blanking of the stay cable, polyethylene sheaths with certain lengths are stripped at two ends, steel wires are dispersed and penetrate into anchor plates, then chill filling materials (namely chill filling materials) are filled into anchor cups, gaps between the steel wires and the anchor cups are filled, chill anchor cones are formed, and when the stay cable is loaded, the chill anchor castings transmit acting forces on the steel wires to the anchor cups, so that reliable anchoring of the stay cable is realized. In the embodiment, the anchor cup conical cavity is anchored by adopting a cold casting anchor filling material 1, and the straight cylinder cavity in which the parallel steel wires are positioned is anchored by adopting a cold casting anchor filling material 2. The two are different in stacking modes adopted by the first-stage steel balls, wherein a quadrangular stacking model is adopted by the conical cavity, and a triangular stacking model is adopted by the straight cylinder cavity.
The composition design scheme of the cold casting anchor irrigation material in the embodiment is specifically as follows:
1. steel ball grading principle and hardness requirement
The steel balls are aggregates for forming the stay cable chill filling material, and the steel balls with different diameters are graded according to a certain stacking model, so that the void ratio and the total surface area of the steel ball aggregates in the chill filling material are smaller, the skeleton action of the steel balls in the chill filling material is fully reflected, and the compactness, the strength and other performances of the chill filling material are improved.
The empirical formula of compressive strength of the chill filling is fc=fe/(1-v)
Wherein: fc is the theoretical compressive strength of the chill casting filler;
fe is the bonding strength of the epoxy resin;
v is the compactness of the steel ball.
In order to meet the requirements, for the cold casting filler with the theoretical compressive strength of more than 170MPa, if the bonding strength of the cured epoxy resin is more than 80MPa, the compactness of the steel ball is more than 53%.
The size and grading of the steel balls simultaneously influence the fluidity and cohesiveness, namely pouring manufacturability, of the stay cable chill casting filler. The fluidity refers to the ability of the cold casting filler mixture to overcome internal resistance and resistance among the cold casting filler, the anchor and the steel wire under the self weight or the vibration action of construction machinery, generate flow and evenly and compactly fill gaps among the anchor and the steel wire. The fluidity directly influences the difficulty of pouring and vibrating construction and the quality of the solidified cold casting filler, and if the steel ball is too large in size and the fresh cold casting filler is too dry and thick, the molding and tamping of the fresh cold casting filler are difficult, and defects such as internal or surface holes and the like are easily caused; if the newly mixed cold casting filler is too thin, layering segregation phenomenon that the epoxy resin slurry floats upwards and large-particle aggregates such as steel balls sink easily occurs after vibration, and the uniformity of the quality of the cold casting filler and the forming compactness are affected. The cohesiveness refers to the ability of the chill filler mixture to maintain overall uniformity without segregation by delamination during casting. Cold cast filler with poor cohesiveness is easy to cause separation of steel balls and epoxy resin slurry, and honeycomb, holes and the like are easy to appear after vibration. Too high cohesiveness can easily cause poor fluidity of the chill casting filler, and difficult pouring, vibrating and molding. When the diameter of the steel ball is larger, the epoxy resin slurry to be wrapped is less, the fluidity is better, but the cohesiveness is poorer.
For the stay cable with ultra-high strength and high fatigue resistance with the phi of 7mm-2100MPa, the grouting process performance (the gap between the anchorage devices and the gap between the steel wires) is considered, and the following steel ball grading method is provided.
In the chill filling mixture, the small steel balls fill the gaps of the large steel balls, the epoxy resin fills the gaps of the small steel balls and the large steel balls, and a certain amount of epoxy resin is used for wrapping the surfaces of the steel ball aggregates, so that the steel ball aggregates are lubricated, and the chill filling mixture has better fluidity (good anchor filling process performance) and higher compactness (compression strength improvement). However, the too many small steel balls and the relatively increased content of fine aggregates of the small steel balls obviously increase the total surface area of the aggregates of the small steel balls, the epoxy resin coating the surfaces of the steel ball particles is insufficient, and the increase of the internal friction resistance among the small steel balls becomes a main cause for reducing the fluidity of the chill filling mixture, so that the fluidity of the chill filling is gradually reduced by increasing the number of the small steel balls. Therefore, there is a small steel ball to large steel ball ratio to maximize fluidity and maintain good cohesiveness of the chill casting filler mix.
As the maximum gap between the stay cable steel wire bundles with the diameter of phi 7mm-2100MPa is 2-4 mm and the gap between the steel wire bundles and the anchorage is 5-10 mm, the diameter D of the primary steel ball is determined 1 Is 1-2mm to ensure that the cold casting filler can flow into the gaps of the steel wire bundles and the gaps between the anchor and the steel wires, and ensure that the compactness of the cold casting body reaches more than 95 percent.
(1) Grading according to quadrilateral stacking principle
For larger-size anchors, because the size of the anchor is larger, the gap between the anchor and the steel wire is also larger, and the primary steel balls are stacked according to a quadrilateral, and small steel balls are embedded in the gap between the primary steel balls. The diameter of the first-stage steel ball is D 1 The diameter of the second-level steel ball is D 2 ，D 2 ＝0.41D 1 。
According to the principle, the volume ratio of the steel balls of the chill casting filler is calculated as follows:
spatial volume: v=d 1 ×D 1 ×D 1
First-stage steel ball volume: v (V) 1 ＝4π/24(D 1 ×D 1 ×D 1 )
Volume of the secondary steel ball: v (V) 2 ＝4π/24(D 1 ×D 1 ×D 1 ×0.41×0.41×0.41)
Steel ball solidity v=55.69%
The strength requirement of the cold casting filler can be met theoretically.
Steel balls with the same mass, the smaller the diameter of the steel balls, the larger the total surface area; the larger the diameter, the smaller the total surface area, and thus the smaller the epoxy material that is required to coat the surface of a large diameter steel ball. Namely, the epoxy resin layer coated on the surface of the large-diameter steel ball is thicker than the epoxy resin layer coated on the small-diameter steel ball with the same epoxy resin dosage, and the friction between the steel balls is correspondingly reduced. However, the maximum diameter of the steel ball with the chill filling material is increased, so that the bonding between the steel ball and the interface of the epoxy resin body can be weakened, and the discontinuity of the internal structure is increased; the large-diameter steel ball plays a constraint role in epoxy curing shrinkage, and because the elastic modulus of the large-diameter steel ball and the epoxy curing shrinkage are different, the tensile stress is generated in the cold casting filler, the diameter of the large-diameter steel ball is increased, and the internal tensile stress is increased; therefore, reducing the diameter of the steel balls in the chill material can increase the compressive strength of the chill packing.
Based on the above consideration, the combination of the large-diameter steel balls and the small-diameter steel balls is adopted to give consideration to smaller friction force between the steel balls and higher compressive strength, and in summary, the grouting process performance (the gap between an anchor and a steel wire bundle, the gap between steel wires, general D 1 Is 1.00 mm-2.00 mm, D 2 Then 0.41 to 0.82mm.
The volume ratio (weight ratio) of the large steel ball to the small steel ball is about 1:0.13.
the principle of grading by adopting the quadrilateral stacking principle is to ensure that a small steel ball is filled among four large steel balls, so that the volume ratio of the small steel ball to the large steel ball is more than 10%, the cohesiveness of the cold casting filler is improved, and the grouting compactness of the large-specification high-strength stay cable anchor is ensured.
(2) Grading according to triangle stacking principle
The first grading is mainly aimed at small-specification anchorage devices, the gap between the anchorage devices and the steel wires is smaller, the large steel balls are considered to be stacked according to a triangle, and the diameter of the largest steel ball is D 1 The diameter of the second-level steel ball is D 2 ，D 2 ＝0.15D 1。
According to the principle, the volume ratio of the steel balls of the chill casting filler is calculated as follows:
spatial volume: v= v3/4 (D 1 ×D 1 ×D 1 )
Large steel ball volume: v (V) 1 ＝4π/24(D 1 ×D 1 ×D 1 )/2
Small steel ball volume: v (V) 1 ＝4π/24(D 1 ×D 1 ×D 1 ×0.15×015×0.15)
Steel ball solidity v=60%
Considering the performance of the grouting process (gap between anchor and wire bundle, gap between wires, general D 1 Is 0.8 mm-1.8 mm, D 2 Then 0.12 to 0.24mm.
The volume ratio (weight ratio) of the ingredients of the big steel ball to the small steel ball is about 1:0.04
The principle of grading by adopting the triangle stacking principle is to ensure that a small steel ball is filled among three large steel balls, so that the volume ratio of the small steel ball to the large steel ball is more than 4%, the fluidity of the cold casting filler is improved, and the grouting manufacturability of the small-specification high-strength stay cable anchor is ensured.
(3) Hardness requirement of steel ball
The steel ball should have a hardness higher than that of the stay cable wire so that when the chilled anchor is compressed, the steel ball will press against the surface of the wire and the inner wall of the anchor cup to form a partial engagement therebetween, thereby reducing deformation and slippage of the chilled anchor. With the improvement of the strength of the steel wire, the surface hardness of the steel wire with the phi of 7mm-2100MPa is HRC 55-60, and the hardness of the steel ball is HRC 60-70.
2. Bisphenol A diglycidyl ether epoxy resin requirement
The strength grade of the epoxy resin is the most important factor affecting the compressive strength of the chill casting filler. In the chill filling material, the strength of the epoxy resin directly influences the strength of the chill filling material because the epoxy resin bonds with the steel balls, and under the condition of the same mixing ratio, the higher the strength of the epoxy resin is, the higher the bonding strength of the epoxy resin and the steel balls is, and the higher the strength of the chill filling material is.
The epoxy resin is used as the adhesive of the stay cable cold-casting anchoring filler, and the soft resin with high strength, good adhesiveness, no byproducts in the curing process, good chemical stability and good ageing resistance is selected to strengthen the adhesive force of the cold-casting body and reduce the shrinkage of the cold-casting body after being pressed.
The epoxy resin adopts bisphenol A diglycidyl ether epoxy resin with chemical formula of (C) 21 H 24 O 4 ) X The relative molecular mass of the epoxy resin is critical to the bonding properties of the stay cable chill casting filler. The adhesive has the advantages of low relative molecular mass, low viscosity, high fluidity, easy wetting and convenient adhesion, but the adhesive layer is easy to cohesive failure due to low cohesive force and low adhesive strength. If the relative molecular mass is large, the viscosity is also large, the wettability to the surface of an adherend is poor, the cohesive force is larger, and the high adhesive strength is not easily obtained. Therefore, only the epoxy glue stock with medium relative molecular mass has larger adhesive force and certain cohesive force, and has good adhesive property and high strength.
In order to obtain ideal bonding effect, for the ultra-high strength steel wire stay cable with the diameter of 7mm to 2100MPa, the similar bisphenol A diglycidyl ether epoxy resin with different relative molecular masses of EP01441 and EP01451 is mixed for use, so that the resin sizing material with medium relative molecular mass can be obtained. The EP01441 resin has low molecular weight, 184-195 g/mol epoxide equivalent, low viscosity, good wettability, higher adhesive strength than EP01451 resin and less cohesive force. Whereas EP01451 epoxy resin is quite contrary, the molecular weight of the resin is high, the epoxy equivalent is 210-230 g/mol, the viscosity is high, the wettability is poor, the bonding strength is low, but the cohesive force is high.
The invention proposes that the mixed epoxy resin obtained by mixing the EP01441 bisphenol A diglycidyl ether resin and the EP01451 bisphenol A diglycidyl ether resin according to the mass ratio of 5:5, 6:4 or 4:6 has the advantages of not lower than 20MPa, not lower than 80MPa of compressive strength and good fluidity because of the mutual complement. Meanwhile, in order to further improve the high temperature resistance of the epoxy resin in the chill casting filler, heat-resistant filling materials such as bisphenol A-organosilicon condensate, aluminum powder and the like are added into the epoxy resin, so that the heat-resistant temperature of the epoxy resin is improved to be more than 300 ℃.
3. Curing agent requirement
Bisphenol A diglycidyl ether epoxy resin is a linear thermoplastic resin, does not harden, does not have any use performance, and has excellent use performance and practical value only by adding a curing agent and reacting with the curing agent to crosslink the bisphenol A diglycidyl ether epoxy resin into a three-dimensional net-shaped or body-shaped structure from a linear structure to form insoluble and infusible matters; and the performance of the cured product is greatly dependent on the curing agent, and the structure and quality of the curing agent directly influence the application effect of the epoxy resin, so the curing agent is an important component part of the epoxy resin after being molded.
In order to improve the compressive strength of the chill filling material, the curing agent adopts phenolic amine micromolecule curing agent, the molecular structure of the curing agent contains rigid benzene ring structure, the distance between the rigid benzene ring structure and the crosslinking point of the epoxy group is small, and the steric hindrance of the benzene ring is large, so that the chemical bond between the crosslinking points is difficult to rotate, and therefore, the compressive strength and the compressive elastic modulus of the chill filling material adopting the curing agent are large. Maleic anhydride or similar materials can also be used as the curing agent of ultra-high strength steel wire stayed cable cold cast materials with the diameter of 7mm to 2100MPa, and the anhydride curing agent reacts with hydroxyl groups in the epoxy resin to generate monoester containing one carboxyl group, and the monoester is used for initiating the curing of the epoxy resin. The curing reaction rate is related to the hydroxyl groups in the epoxy resin, the curing reaction rate of the epoxy resin with low hydroxyl concentration is slow, and the curing reaction rate is fast when the hydroxyl concentration is high. The amount of the acid anhydride curing agent is about 0.85 times that of the epoxy resin.
In addition, since the reactivity of the acid anhydride curing agent with the epoxy resin is weak, curing at a high temperature is required, and thus the hydroxyl group and the epoxy group of the epoxy resin may undergo esterification reaction with the acid anhydride. The addition of small amounts of tertiary amines, phenols, etc. to the epoxy-anhydride system can shorten the curing time and lower the reaction temperature.
4. Epoxy resin filling filler
The filling material can improve mechanical property, thermal property and electrical property for bisphenol A diglycidyl ether epoxy resin, especially reduce shrinkage rate of the material. The addition of the filler can reduce the internal stress of the material, improve the dimensional stability and improve the flame retardance, heat resistance and heat conductivity of the epoxy resin. Considering service life of the stay cable anchoring system over 50 years and fire resistance of the anchor head, the epoxy filling material in the ultra-high strength steel wire stay cable cold casting material with the phi of 7mm-2100MPa is preferably alumina with the particle size of 30-150 mu m. The alumina is used as a high-quality inorganic filling material with high hardness, chemical corrosion resistance, high temperature resistance and fire resistance, and can reduce the temperature rise and the curing shrinkage rate caused by the heat release of the curing reaction of the epoxy resin, reduce the linear expansion coefficient of a cured product, and improve the performances of the epoxy resin, such as bending strength, tensile strength, impact strength and the like. The volume usage of the alumina is 10-30% of the volume usage of the epoxy resin. In addition, for the subsequent high temperature resistance, the fire-resistant filling filler also comprises quartz powder, wherein the fineness of the quartz powder is as follows: 80% or more of the particles smaller than 1 μm have an average particle diameter of: 0.1-0.3 mu m, melting point: 1650 ℃, relative density: 2.65, the volume dosage of the quartz powder is 10 to 20 percent of the volume dosage of the bisphenol A diglycidyl ether resin
5. Other auxiliary agent requirements
In order to improve the toughness and plasticity of the chill casting filler, dibutyl phthalate (DBP), dioctyl phthalate (DOP), tricresyl phosphate (TCP) and other materials are adopted as plasticizer of the ultra-high strength steel wire stay cable chill casting material with the diameter of phi 7mm-2100 MPa. The dosage of the plasticizer is 2 to 10 percent of the mass of the epoxy resin.
The ultra-high strength steel wire stay cable cold casting material with the phi of 7mm-2100MPa is designed by filling gaps of large-diameter steel ball aggregates with small-diameter steel ball aggregates and uniformly distributing epoxy materials on the surfaces of coarse and fine aggregates consisting of large-diameter steel balls and small-diameter steel balls. Therefore, the chill casting material is unevenly stirred, and the chill casting filler with high strength, high fatigue resistance and high toughness and plasticity cannot be obtained. By adopting mechanical stirring, not only can the stirring speed and the uniformity of the mixture be improved, but also the strength of the chill casting filler can be improved, and the labor intensity and the productivity can be greatly reduced.
For the above fillers, a vertical forced type cold casting filler stirrer is provided, the working principle of which is shown in fig. 4, and the stirring materials are forcedly stirred by the rotating stirring blades. The stirring mechanism consists of a stirring shaft which is vertically or horizontally arranged in the stirring barrel, a stirring blade is arranged on the stirring shaft, and when the stirring mechanism works, the motor drives the rotating shaft, and the rotating shaft drives the blade to perform forced stirring actions such as shearing, extrusion, overturning and pushing on materials in the barrel, so that the chill casting material consisting of the steel balls and the epoxy resin is uniformly stirred in severe relative motion. The forced stirrer has the advantages of good material mixing quality and high efficiency.
On the other hand, the homogeneous cold casting filler mixture is between solid and liquid, and the internal particles are in a suspension state by virtue of friction force and cohesive force among materials. When the chill filler mixture is vibrated, the energy of the vibrator is transmitted to the material particles in a pulse mode to force the particles to participate in vibration, the vibration energy eliminates the friction force among the materials at the moment, and the substances without internal friction are in a liquid state, so the chill filler mixture is temporarily liquefied and is in a liquefied state. The cold casting filler mixture can be filled in the container just like liquid, so that bubbles can be forced to float upwards, and air and pores in the original mixture are removed; the material particles sink under the action of gravity, and are simultaneously disturbed by vibration to form a compact structure. In this way, the cold casting filler is shaped and compacted by vibration. Whether or not the chill is tapped is related to the frequency and amplitude of the vibration. The material has self vibration frequency, when the vibration source frequency is the same as or close to the vibration frequency of the material, resonance phenomenon can occur, so that the amplitude is obviously improved, and the vibration effect is enhanced. Generally, high frequencies are better for finer particles, while low frequencies are more effective for coarser particles, so the frequency of vibration is generally selected based on the size of the material particles. When larger amplitude vibration is adopted, the vibration time required by compacting the chill filling is shortened; conversely, the required vibration time is prolonged; if the amplitude is too small, a good compaction effect cannot be achieved; the excessive amplitude may cause segregation of the chill.
Based on the mechanism, the invention provides a method for installing a vibrator on a stay cable anchor in the anchor filling process.
The method is to fix the vibrator on the anchor by using bolts or pincer-shaped clamps, and the vibration energy of the vibrator is transmitted to the chill filling material through the anchor, so that the chill filling material is vibrated and compacted. The amplitude of the vibrator is between 0.5mm and 3.0mm, and the frequency of the vibrator is between 50Hz and 300 Hz. For small-size anchorage devices, high-frequency low-amplitude is adopted, and for large-size anchorage devices, low-frequency high-amplitude is adopted.
When the vibrator is used, the vibration acting distance is about 250mm, and when the diameter and the length of the anchor are larger than 250mm, the vibrators are arranged on two sides of the anchor to vibrate simultaneously, and one vibrator is arranged every 250 mm. The vibrator is started to vibrate after the cold casting filler is filled into the anchor, the pouring height of the cold casting filler is higher than the installation position of the vibrator, and when the gap between the steel wire is smaller or the gap between the steel wire and the anchor is deeper and narrower, a method of pouring and vibrating can be adopted; the external vibrator should be closely connected with the anchor, and the vibration time is controlled based on the condition that the chill filling material no longer generates bubbles and the surface is horizontal.
By implementing the measures, the compressive strength of the chill casting is greatly improved. After the stay cable bears the tensile load, the compression force is formed on the steel wire by the bonding force of the cold casting body and the steel wire and the compression action of the inner cone of the anchor device on the cold casting body, so that the load of the stay cable body is transferred to the stay cable anchoring system. Thus, the chill casting is a compression member which breaks in a predominantly compressive manner. The process of compressive fracture of the chill is essentially a process in which cracks continue to propagate within the chill. The interface transition area between the steel ball and the epoxy resin is the weakest link in the cold casting filler, and local cracks are easy to occur. After the chilled casting body caused by the bearing of the stay cable is pressed, the loading causes the interface area to initiate crack growth first, which is the interface crack growth. When the load is further increased, the crack of the epoxy resin is expanded at the same time of the crack expansion of the interface. With continuous loading, the interfacial cracks of the steel ball and the epoxy resin and the self cracks of the epoxy resin are continuously expanded and gradually communicated with each other, and the chill casting body is damaged.
The strength of the chill casting body under unidirectional pressure is uniaxial compressive strength, commonly referred to as chill casting body compressive strength. According to the national standard 'hot extrusion polyethylene high-strength steel wire inhaul cable for cable-stayed bridge' (GB/T18365-2018), when the stayed cable is anchored, three cylindrical cubic test pieces with the diameter of 25mm multiplied by 30mm are manufactured in the same furnace, and under the standard condition (the temperature (23+/-5) DEG C), the measured compressive strength is the compressive strength of a mixed-cooled cast body test piece, and the measured compressive strength is expressed by fcc and is calculated according to the following formula:
fcc＝F/A
in the middle of
fcc-compressive strength of the chill casting, MPa, to the nearest 0.1MPa;
f-limit load, N;
a-area under pressure, mm 2 。
The test process should be continuously and evenly loaded, and the loading speed is 0.8-1.0 MPa/s.
The arithmetic average of the measured values of the three test pieces was used as the measured value, and the test result was calculated to 0.1MPa. If the difference between any measured value and the intermediate value exceeds 15% of the intermediate value, the intermediate value is taken as the measured value; if the difference between the two measured values exceeds 15% of the median value, the test results are not valid.
Through the measures, the compressive strength of the chill casting body can reach 170MPa to 230MPa.
The stay cable adopting the cold casting filler has the tensile strength of the stay cable with the upper stress limit of 40 percent, the high stress amplitude of 280MPa and the fatigue cycle of 200 ten thousands times, and the anchoring is not invalid.
In addition, the stay cable anchor head adopting the heat-resistant type cold casting filler is loaded for 30 minutes according to 40% stay cable breaking load under the action of 300 ℃ and the anchoring is not invalid.
Claims (10)
1. An ultra-high strength, high anti-fatigue and high temperature resistant stay cable cold casting anchor irrigation material is characterized in that: comprises steel balls, bisphenol A diglycidyl ether resin, curing agent, fire-resistant filling filler and toughening agent; the steel balls comprise steel balls with more than two diameters, the bonding strength fe of the bisphenol A diglycidyl ether resin after curing is more than 80MPa, and the compactness v of the steel balls is more than 53%.
2. The ultra-high strength, high fatigue resistance, high temperature resistant stay cable cold cast anchor casting material of claim 1, wherein: the steel ball consists of a first-stage steel ball and a second-stage steel ball, and the diameter D of the first-stage steel ball 1 Diameter D of the secondary steel ball is 1-2mm 2 Diameter D smaller than the first-stage steel ball 1 The second steel balls are filled in the stacking gaps of the first steel balls.
3. The ultra-high strength, high fatigue resistance, high temperature resistant stay cable cold cast anchor casting material of claim 2, wherein: for large-scale anchorage devices: the inner diameter of the anchorage device is larger than 250mm, the first-stage steel balls simulate quadrilateral stacking, small steel balls are embedded in gaps among the first-stage steel balls, and the diameter D of the second-stage steel balls is set 2 ＝0.41D 1 The steel ball compactness v=55.69% corresponding to the stacking mode 。
4. The ultra-high strength, high fatigue resistance, high temperature resistant stay cable cold cast anchor casting material of claim 2, wherein: aiming at the small-specification anchorage device, the inner diameter of the anchorage device is less than or equal to 250mm, the primary steel balls simulate triangular stacking, small steel balls are embedded in gaps among the primary steel balls, and the diameter D of the secondary steel balls is set 2 ＝0.15D 1 The steel ball compactness v=60% corresponding to the stacking mode 。
5. The ultra-high strength, high fatigue resistance, high temperature resistant stay cable cold cast anchor casting material of claim 4, wherein: in the case of small-sized anchors,diameter D of primary steel ball 1d The value range is 0.8-1.8mm, D 2 The range of the value of (C) is 0.12-0.24mm.
6. The ultra-high strength, high fatigue resistance, high temperature resistant stay cable cold cast anchor casting material of claim 1, wherein: the hardness of the steel ball is HRC 60-70.
7. The ultra-high strength, high fatigue resistance, high temperature resistant stay cable cold cast anchor casting material of claim 1, wherein: EP01441 epoxy resin with 184-195 g/mol of epoxy equivalent and EP01451 epoxy resin with 210-230 g/mol of epoxy equivalent are mixed according to the mass ratio of (4:6) to (6:4), and the obtained mixed epoxy resin has bonding strength not lower than 20MPa and compressive strength not lower than 80MPa.
8. The ultra-high strength, high fatigue resistance, high temperature resistant stay cable cold cast anchor casting material of claim 1, wherein:
the curing agent is one of a phenolic amine type small molecule curing agent and an anhydride type curing agent, and the dosage of the anhydride type curing agent is 0.85 time of the weight of the bisphenol A type diglycidyl ether resin;
the refractory filling filler is alumina and quartz powder, the volume consumption of the alumina is 10% -30% of the volume consumption of bisphenol A diglycidyl ether resin, and the fineness of the quartz powder is as follows: 80% or more of the particles smaller than 1 μm have an average particle diameter of: 0.1-0.3 mu m, melting point: 1650 ℃, relative density: 2.65, the volume consumption of the quartz powder is 10-20% of the volume consumption of the bisphenol A diglycidyl ether resin;
the toughening agent is selected from one or more of dibutyl phthalate, dioctyl phthalate and tricresyl phosphate, and the dosage of the toughening agent is 2-10% of the weight of the bisphenol A diglycidyl ether resin.
9. An anchor irrigation method of an ultra-high strength, high fatigue resistance and high temperature resistance stay cable cold casting anchor irrigation material is characterized in that: the anchor pouring materials are uniformly mixed and stirred to obtain liquefied cold casting anchor pouring materials, a vibrator is arranged on the anchor, vibration energy of the vibrator is transmitted to the cold casting anchor pouring materials through the anchor during anchor pouring, the vibration amplitude of the vibrator is between 0.5mm and 3.0mm, and the frequency of the vibrator is between 50Hz and 300 Hz.
10. The method according to claim 9, wherein: when the diameter and the length of the anchor are larger than 250mm, the vibrators are arranged on two sides of the anchor to vibrate simultaneously, one vibrator is arranged every 250mm, after the cold cast anchor pouring material is poured into the anchor, the vibrators are started to vibrate, the pouring height of the cold cast anchor pouring material is higher than the mounting position of the vibrator, and when the gap between the steel wire is smaller or the gap between the steel wire and the anchor is deeper and narrower, a method of pouring and vibrating simultaneously is adopted; the external vibrator is tightly connected with the anchor, and the vibration time is based on the condition that no bubbles appear in the cold casting anchor pouring material and the surface is horizontal.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311541253.5A CN117683329A (en) | 2023-11-20 | 2023-11-20 | Super-strength, high-fatigue-resistance and high-temperature-resistance stay cable cold-cast anchor grouting material and anchor grouting method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311541253.5A CN117683329A (en) | 2023-11-20 | 2023-11-20 | Super-strength, high-fatigue-resistance and high-temperature-resistance stay cable cold-cast anchor grouting material and anchor grouting method |
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