Concrete pole reinforcing structure and reinforcing method based on UHPC (Ultra High Performance Concrete)

Abstract

The invention relates to the technical field of crossing of electric power engineering and civil engineering, in particular to a concrete electric pole reinforcing structure and method based on UHPC and an original concrete electric pole. The interface treatment layer comprises an epoxy interface agent coated on the surface of the original concrete electric pole and embedded steel bars embedded into the original concrete electric pole; the UHPC reinforcing layer wraps the original concrete pole and is bonded with the interface processing layer; optionally, additional longitudinal bars and annular stirrups are included, the additional longitudinal bars are evenly arranged along the circumference of the electric pole and extend into the UHPC reinforcing layer, and the annular stirrups surround the additional longitudinal bars and are bound with the additional longitudinal bars. The method is suitable for existing concrete electric poles with cracks, steel bar corrosion, concrete stripping and other diseases in 110-500 kV high-voltage transmission lines and durability enhancement protection of newly-built electric poles, and can be stably applied to severe environments such as coastal corrosion, severe cold freezing and thawing and industrial area pollution.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of power engineering and civil engineering, in particular to a concrete electric pole reinforcing structure based on UHPC and a reinforcing method. BACKGROUND

[0002] As an important supporting structure of power and communication infrastructure, the concrete electric pole is exposed to complex environments for a long time, and is prone to cracks, steel corrosion, concrete spalling, strength reduction and other diseases. The traditional replacement method has high cost, long construction period and great influence on power supply and communication. Therefore, it is of great significance to develop efficient, reliable and economical structure repair and reinforcement technology to ensure the safe operation of infrastructure and prolong the service life.

[0003] With the increase of service life and environmental load, the concrete electric pole is prone to typical diseases such as cracks, steel corrosion, concrete spalling and overall stiffness reduction. At present, the reinforcement technologies for concrete electric poles at home and abroad mainly include four categories: external steel plate reinforcement, carbon fiber cloth pasting reinforcement, ordinary concrete spraying reinforcement and grouting reinforcement. Among them, the external steel plate reinforcement is suitable for scenes of severe damage and short-term emergency reinforcement, but the steel plate weighs 50-80 kg / m, is prone to corrosion, needs to be painted regularly, and the construction process is easy to damage the original pole; the carbon fiber cloth pasting reinforcement is suitable for scenes of slight cracks and high appearance requirements, but its shear performance is poor, the performance decays at high temperature, the adhesive is prone to aging, and the cost is high; the ordinary concrete spraying reinforcement method is suitable for concrete spalling repair, but the ordinary concrete has low strength, poor durability and weak adhesion with the original pole, and is easy to peel off; the grouting reinforcement method is suitable for fine cracks, but this method only repairs cracks and cannot improve the overall bearing capacity, and the slurry shrinkage rate is high and easy to crack again.

[0004] In addition, the concrete electric pole reinforcing device disclosed in the Chinese patent CN119221732A can move the reinforcing hoop on the surface of the electric pole and reinforce the electric pole at any height by using the pull line hoop and the guide hoop to cooperate with the pull line to adjust the position of the reinforcing hoop. However, the pull line adjustment requires the installation of multiple pulley groups, and the device also needs to be adjusted, which has high requirements for construction level, and the pull line and pulley group exposed outside are easy to be corroded and damaged. At the same time, the reinforcing segment covered by the pull line adjustment has a small coverage range, which is not helpful for the severely damaged electric pole.

[0005] A concrete pole reinforcing device is disclosed in Chinese patent with publication number CN204663119U, which comprises a fastening bolt and a fastening nut, and is characterized in that the fastening bolt and the fastening nut are locked and fixed through a bolt hole to form a ring-shaped whole. Although the technical solution is easy to construct, it has the same shortcomings as the outer steel plate reinforcement, i.e., it is easy to corrode and needs to be painted regularly, and it needs to be welded during construction, which can damage the original pole and can only be used as a temporary remedial measure.

[0006] A concrete pole reinforcing device is disclosed in Chinese patent with publication number CN212105351U, which comprises a support steel pipe, a hoop I, a hoop II, a reverse lock and a steel pile. The device has the advantages of easy construction, low material cost, short construction time and prevention of further tilting of the pole. However, the reinforcing strength is not high, the original defects of the pole body are not repaired, and the reinforcing device occupies a large space and can interfere with the normal use of other facilities.

[0007] A concrete pole reinforcing method is disclosed in Chinese patent with publication number CN101748901A, which comprises the following steps: cutting a flat glass fiber reinforced plastic cylindrical template into an unfolded surface of the outer surface of the annular pole to be repaired, then applying structural adhesive to the inner surface of the template, directly rolling the template along the annular outer surface so that the inner surface of the template is tightly attached to the outer surface of the pole, and finally adding a detachable hoop to the surface of the template. After the structural adhesive is completely solidified, the hoop is removed. Although the method is easy to construct, has low cost, light weight and good flexibility of the material, it has the same shortcomings as the carbon fiber cloth reinforcement method, i.e., the adhesive is prone to aging.

[0008] In summary, there is an urgent need to develop a concrete pole reinforcing technology that has high adhesion, high durability and high bearing capacity, and is easy to construct and has reasonable cost, in order to solve the service safety problem of old poles. SUMMARY

[0009] In view of this, the present application provides a UHPC concrete pole reinforcing structure and a reinforcing method, which realizes efficient repair and performance improvement of the pole through the design of interface strengthening, UHPC reinforcing layer and integrated maintenance, to solve the problems existing in the prior art.

[0010] To achieve the above-mentioned purpose, the present application provides a UHPC concrete pole reinforcing structure, which comprises: a original concrete pole; an interface treatment layer, which comprises an epoxy interface agent coated on the surface of the original concrete pole and a bonded rebar implanted in the original concrete pole; a UHPC reinforcing layer, which is wrapped outside the original concrete pole and is bonded with the interface treatment layer; Optionally, additional longitudinal reinforcement and ring-shaped stirrups are included, the additional longitudinal reinforcement is uniformly arranged along the circumference of the electric pole and extends into the UHPC reinforcing layer, and the ring-shaped stirrups encircle the additional longitudinal reinforcement and are tied with the additional longitudinal reinforcement.

[0011] Optionally, the bonding strength of the epoxy interface agent is not less than 4 MPa, and the solid content is not less than 90%.

[0012] Optionally, the reinforcing bar has a HRB400E grade, a diameter of Φ8-12 mm, an embedding depth of 80-120 mm, and a spacing of 150-200 mm.

[0013] Optionally, the UHPC reinforcing layer has a material strength grade of C120-C150, a compressive strength of not less than 120 MPa, a flexural strength of not less than 15 MPa, a permeability coefficient of not more than 1×10 -12 m / s, and a frost resistance grade of not less than F300. The thickness of the UHPC reinforcing layer is determined according to the disease degree, when the disease is slight, the crack width is less than 0.5 mm, and the thickness is 50 mm; when the disease is moderate, the crack width is 0.5-1.0 mm, and the thickness is 60-80 mm; and when the disease is severe, the crack width is greater than 1.0 mm, and the thickness is 80-100 mm.

[0014] Optionally, the additional longitudinal reinforcement has a HRB400E grade, a diameter of Φ12-16 mm, and a number of 4-8, and is uniformly arranged along the circumference of the electric pole and welded with the original pole reinforcement. The ring-shaped stirrup has a HPB300 grade, a diameter of Φ6-8 mm, and a spacing of 100-150 mm, and is tied with the additional longitudinal reinforcement.

[0015] In another aspect to achieve the above object, the application provides a UHPC-based concrete electric pole reinforcing method, comprising the following steps: Step one: non-destructive testing of the original concrete electric pole to determine the concrete strength, crack width, and reinforcement corrosion rate; Step two: high-pressure water cleaning, chiseling treatment, and reinforcing bar construction on the surface of the original pole; Step three: installation of a customized mold, the mold being a semicircular steel mold provided with a feeding port and an exhaust port; Step four: preparation of UHPC material and pouring into the customized mold, vibration compaction, and construction of a UHPC reinforcing layer; Step five: curing of the UHPC reinforcing layer; Step six: appearance, strength, bonding force, and bearing capacity testing of the reinforced concrete electric pole.

[0016] Optionally, in the step two, the chiseling depth is not less than 5mm, and the surface roughness is not less than 2mm; the epoxy mortar is injected into the anchorage hole, and the compressive strength is not less than 60MPa.

[0017] Optionally, in the step four, the proportioning of the UHPC material comprises: Cement: Silica Fume: Quartz Sand: Steel Fiber: Water Reducing Agent: Water = 1:0.2:1.2:0.02:0.02:0.16; The initial fluidity is not less than 250mm, and the initial setting time is not less than 2 hours.

[0018] Optionally, in the step five, the curing mode comprises: Covering geotextile for moisture curing for 7 days under normal temperature environment; In a low-temperature environment, steam curing is adopted, the temperature is controlled at 60±5℃, the humidity is not less than 90%, and the curing time is not less than 4 hours.

[0019] Optionally, in the step six, the interface bonding strength of the bonding force test is not less than 3MPa, and the anti-bending bearing capacity of the bearing capacity test is restored to more than 110% of the original design value.

[0020] Compared with the prior art, the beneficial effects of the present application are: The reinforcing structure of the present application forms a firm connection between the UHPC reinforcing layer and the original electric pole through the double interface treatment of the epoxy interface agent and the anchorage bar, significantly improves the interface bonding strength, and ensures that the two can effectively work together when stressed. The anchorage bar penetrates into the original pole and the reinforcing layer, further enhancing the interface shear capacity, solving the common interlayer peeling problem in traditional reinforcement methods.

[0021] The UHPC material with optimized proportioning has excellent compressive and bending strength, which can comprehensively improve the comprehensive bearing capacity of the electric pole. The reasonable configuration of the additional longitudinal reinforcement and ring hoop reinforcement further enhances the bending and shear performance of the structure, and even the severely damaged electric pole can restore and exceed the original design level.

[0022] The UHPC material used in the present application has extremely low permeability and excellent freeze-thaw resistance, which can effectively resist the invasion of harmful media such as chloride ions and water, and slow down the corrosion rate of the internal steel bar. The reinforced electric pole can still maintain long-term stability in harsh environments such as coastal salt fog and severe freezing and thawing, significantly prolonging its service life.

[0023] The construction process of the method uses customized templates and standardized on-site operation procedures, greatly shortening the entire reinforcement period. The method has low requirements for construction space, does not require large and heavy equipment or complex welding operations, reduces the construction difficulty and safety risk, and reduces the impact on the normal operation of the power line.

[0024] Compared to carbon fiber reinforcement or complete pole replacement, this method has significant advantages in terms of material and construction costs. Due to the excellent durability of the reinforcement system, it requires virtually no additional maintenance throughout its lifespan, making its overall economic efficiency superior to traditional reinforcement solutions. Attached Figure Description

[0025] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. In the drawings: Figure 1 This is a structural diagram of the UHPC-reinforced concrete pole in an embodiment of the present invention; Figure 2 This is a schematic cross-sectional view of the reinforced structure in an embodiment of the present invention; Figure 3 This is a schematic diagram illustrating the interface processing details in an embodiment of the present invention; Figure 4 This is a schematic diagram of the UHPC reinforcement layer casting template in an embodiment of the present invention; Figure 5 This is a schematic diagram of the load-bearing capacity test of the reinforced utility pole in an embodiment of the present invention; Among them: 1-Original concrete pole, 2-UHPC reinforcement layer, 3-Additional longitudinal reinforcement, 4-Circular stirrup, 5-Rebar installation, 6-Epoxy interface agent, 7-Uncarbonized area of ​​original concrete pole, 8-Roughened surface, 9-Epoxy mortar, 10-Carbonized layer of original pole, 11-Semi-circular steel formwork, 12-Sealing sponge strip, 13-Inlet, 14-Exhaust port, 15-Connecting bolt, 16-Reinforcing rib, 17-Reinforced pole, 18-Horizontal loading cylinder, 19-Force sensor, 20-Displacement gauge, 21-Data acquisition instrument, 22-Fixed support. Detailed Implementation

[0026] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0027] Example 1 This embodiment proposes a reinforcement structure and method for concrete utility poles based on UHPC, such as... Figure 1As shown, the reinforced structure includes the original concrete pole 1, the interface treatment layer (epoxy interface agent 6), the UHPC reinforcement layer 2, the additional longitudinal reinforcement 3, and the ring stirrups 4. The design details of each part are shown in Table 1. Table 1

[0028] As a preferred embodiment, the key details of the above structure are as follows: UHPC material mix ratio: cement, P·O 52.5R; silica fume, active SiO2 ≥ 95%; quartz sand, particle size 0.15-0.6mm; steel fiber, length 12mm, diameter 0.2mm, volume fraction 2%; water-reducing agent, polycarboxylate, water reduction rate ≥ 30%; water = 1:0.2:1.2:0.02:0.02:0.16; The diameter of the hole for anchoring rebar 5 is 4mm larger than that of the rebar. Epoxy mortar is injected into the hole with a compressive strength of ≥60MPa to ensure that the pull-out force of the anchoring rebar is ≥50kN. The top of the UHPC reinforcement layer 2 is equipped with a 15° drainage slope to prevent rainwater from accumulating at the interface between the reinforcement layer and the original pole.

[0029] Figure 2 A schematic diagram of the overall structure of UHPC reinforced concrete poles, by Figure 2 It can be seen that the reinforcement consists of an interface treatment layer (composed of epoxy interface agent 6 and rebar 5) and a UHPC reinforcement layer 2. In addition, additional longitudinal bars 3 and ring stirrups 4 can be used to make deeper reinforcement and strengthening.

[0030] Interface processing layer details Figure 3 The details of the interface treatment are described, and the figure shows the microstructure of the original pole surface roughening, rebar 5, and epoxy interface agent 6. The roughening depth is 5 mm, and the surface roughness is 2 mm to increase the bonding area. The rebar diameter is 10 mm, the insertion depth is 100 mm, and the exposed length is 50 mm, extending into the UHPC layer. The epoxy interface agent 6 is 1 mm thick, and the original pole carbonized layer 10 is removed down to the uncarbonized area. These measures ensure that the interface bond strength reaches over 3 MPa. The rebar 5 is fixed with epoxy mortar, effectively transferring shear force and ensuring a tight bond between the reinforcement layer and the original pole.

[0031] After cleaning and roughening the surface of the original utility pole to obtain a basic working surface, multiple reinforcing bars 5 are arranged on the horizontal circumference of the pole. The reinforcing bars 5 are evenly spaced along the circumference, with a quantity of 4-8 bars. This reinforces the pole itself without requiring excessive construction on the already damaged pole, thus avoiding excessive loss of pole strength. The drilled hole diameter is 4mm larger than the diameter of the reinforcing bar, ensuring smooth insertion and fixation. Epoxy mortar (compressive strength ≥60MPa) is filled into the hole before the reinforcing bar 5 to enhance the bond between the reinforcing bar and the hole wall, allowing them to work well together with the pole. When inserting the reinforcing bar into the hole, ensure the exposed length meets the design requirements, typically 50mm, extending into the UHPC reinforcement layer 2. This allows the reinforcing bar 5 to act as a connection medium between the original pole and the UHPC reinforcement layer 2, deepening the connection between the UHPC reinforcement layer 2 and the utility pole, enhancing the interface bonding force, significantly improving the bond strength between the reinforcement layer and the original pole, and ensuring that both work together to bear the load.

[0032] UHPC reinforcement layer 2 details Figure 4 The diagram shows the formwork for pouring the UHPC reinforcement layer 2. The semi-circular steel formwork is 3 mm thick, with its curvature matching the outer diameter of the pole and the thickness of the UHPC. The formwork length matches the height of the reinforcement area. Inlet 13, 100 mm in diameter, is located at the top of the formwork, while vents 14, 20 mm in diameter, are located on both sides of the bottom, spaced 1 meter apart. Bolt connections are spaced 300 mm apart and are M8×30. A 10 mm thick sealing sponge strip prevents grout leakage. This formwork design ensures dense filling and venting during UHPC pouring, preventing material defects.

[0033] After the rebar installation (5th layer) is completed, the UHPC reinforcement layer 2 will be constructed. The main area to be constructed will be the base of the pole, as it is the critical support structure and the region where internal forces and stresses are concentrated. The base is also the area most vulnerable to external impacts, leading to the most severe damage at the base. Therefore, the construction of the UHPC reinforcement layer 2 will begin at the base. The upward extension of the UHPC reinforcement layer 2 is determined by the longitudinal distribution area of ​​the damage and the pole's height. The thickness of the UHPC reinforcement layer 2 is determined by the width of the cracks in the pole. The UHPC reinforcement layer 2 will wrap around the most severely damaged part of the pole circumferentially. This utilizes the high strength and deformation resistance of UHPC to significantly improve the pole's compressive, bending, and shear strength, restoring severely damaged poles to more than 110% of their original design value and extending the pole's service life.

[0034] Additional longitudinal reinforcement 3 (optional) details During the construction of UHPC reinforcement layer 2, additional longitudinal reinforcement bars can be added appropriately according to the actual damage condition of the utility pole. These additional longitudinal reinforcement bars are distributed circumferentially along the longitudinal direction of the pole's length. HRB400E grade steel bars are used, a high-strength, high-toughness steel bar capable of effectively resisting tensile and bending moments. The diameter of the additional longitudinal reinforcement bars ranges from 12mm to 16mm, with the specific dimensions adjusted according to the pole's diameter and degree of corrosion. The number of additional longitudinal reinforcement bars 3 is between 4 and 8, evenly distributed along the pole's circumference to ensure uniform stress distribution. The additional longitudinal reinforcement bars 3 are placed inside UHPC reinforcement layer 2 and welded to the original pole's reinforcement bars, with the weld length at least 10 times the diameter of the reinforcement bar. The circumferential spacing of the additional longitudinal reinforcement bars 3 is between 60mm and 200mm, with the specific spacing adjusted according to the pole's diameter and degree of corrosion. Furthermore, the additional longitudinal reinforcement 3 is welded to the original pole reinforcement (weld length ≥ 10d, where d is the diameter of the reinforcement) to further strengthen the connection with the pole and enable them to share the load. In addition, the addition of the longitudinal reinforcement can share part of the bending moment, prevent the original reinforcement from being overloaded, and extend the service life of the pole.

[0035] 4 ring stirrups (optional) During the construction of the UHPC reinforcement layer 2, ring stirrups 4 can be appropriately added according to the actual damage condition of the utility pole. The ring stirrups 4 are distributed along the length of the utility pole, forming concentric circles around the pole's cross-section. They are made of HPB300 steel reinforcement, a high-strength, high-toughness steel that effectively resists tensile and bending moments. The diameter of the ring stirrups 4 ranges from 6mm to 8mm, with each ring stirrup spaced 100-150mm apart. The ring stirrups 4 are tied to the additional longitudinal reinforcement 3, with the tying points spaced no more than 200mm apart to ensure a secure connection. This arrangement of ring stirrups 4 restrains the UHPC reinforcement layer 2, limiting its lateral deformation and preventing longitudinal splitting, thereby improving the integrity and shear resistance of the reinforcement layer. The ring stirrups 4 also effectively resist the lateral shear force on the pole, increasing its shear capacity and preventing shear failure. The ring stirrup 4 can also work in conjunction with the additional longitudinal reinforcement: the ring stirrup 4 and the additional longitudinal reinforcement 3 together form a steel reinforcement skeleton, which together enhances the overall strength and rigidity of the pole.

[0036] Figure 5This paper explains the principle of testing the load-bearing capacity of a reinforced utility pole. The diagram shows the horizontal loading device, the arrangement of displacement gauges 20, and the measurement points. The loading point is 6 meters high, simulating the force at the midpoint of the pole. The loading method is horizontal graded loading, with each grade at 5 kN, and a maximum test load of 50 kN. Displacement gauges are positioned at heights of 3 meters, 6 meters, and 9 meters to measure deflection changes. The support is fixed at the bottom to simulate the pole's foundation conditions. Force sensor 19 has a range of 100 kN, and the data acquisition instrument records load and displacement data. This testing method verifies the bending load-bearing capacity of the reinforced pole, ensuring it recovers to more than 110% of the original design value.

[0037] The reinforcement construction method in this embodiment includes six key steps, with a total construction period of no more than two days, and is applicable to the reinforcement of single utility poles.

[0038] Step 1: Disease Detection and Assessment The strength of the original pole's concrete was measured using non-destructive testing techniques such as ultrasonic testing or infrared thermography, and the concrete strength grade was determined by combining rebound hammer testing and core sampling. Simultaneously, the width and length of cracks were measured using a crack width meter to classify the damage as mild, moderate, or severe. The corrosion rate of the reinforcing steel was detected using a steel corrosion meter, and areas with a corrosion rate exceeding 20% ​​were marked to determine whether additional longitudinal reinforcement was needed. This comprehensive assessment of the pole's current condition provides a basis for subsequent reinforcement.

[0039] Step 2: Surface treatment of the original rod This step is fundamental to ensuring the reinforcement effect. A high-pressure water gun at a pressure of at least 8 MPa is used to remove loose dust and oil from the pole. For areas with spalled concrete, a chisel is used to remove loose portions until a solid base surface is exposed. Next, a pneumatic chisel is used to roughen the reinforced area to a depth of at least 5 mm, achieving a surface roughness of at least 2 mm, ensuring an increase in the interface bonding area of ​​at least 30%. For rebar installation, holes are drilled according to the designed spacing. The hole diameter and depth are determined based on the rebar installation parameters. After cleaning the holes with high-pressure air and acetone, epoxy mortar is injected, the rebar is inserted and fixed, and cured for 24 hours to allow the mortar strength to reach at least 40 MPa, thereby enhancing the interface bonding strength.

[0040] Step 3: Custom-made semi-circular steel formwork, 3 mm thick, with an arc matching the pole, is used for formwork installation. The formwork length is determined based on the reinforcement area, typically two to five meters. Formwork panels are bolted together at 300 mm intervals. The gap between the formwork and the original pole is sealed with 10 mm thick sponge strips to prevent grout leakage during UHPC pouring. A 100 mm diameter inlet is provided at the top of the formwork, and a 20 mm diameter vent is provided at the bottom to ensure dense filling during pouring, creating favorable conditions for subsequent UHPC construction.

[0041] Step 4: UHPC Preparation and Casting Process The process strictly adheres to the mixing ratio, prepared at a mixing plant or on-site mobile mixer. The mixing sequence is as follows: first, dry-mix cement, silica fume, and quartz sand for two minutes; then, add water and water-reducing agent and wet-mix for three minutes; finally, add steel fibers and mix for two minutes to ensure uniform dispersion and no agglomeration of the steel fibers. The workability of UHPC is measured, with an initial flowability of not less than 250 mm and an initial setting time of not less than two hours to ensure the operability of the casting process. UHPC is injected into the formwork inlet using pumping or manual pouring. During pouring, a 30 mm diameter vibrator is used for compaction, vibrating for five to ten seconds at each point until dense UHPC overflows from the vent and no air bubbles are released, thus achieving the high-performance application of the material.

[0042] Step 5: Maintenance Phase Depending on environmental conditions, different measures should be taken. When the temperature is not lower than 5 degrees Celsius, geotextile should be covered to retain moisture, and curing should be carried out for seven days to ensure that the UHPC strength reaches 80% of the design value. In extremely cold regions where the ambient temperature is below 5 degrees Celsius, steam curing should be used, with the temperature controlled at 60 ± 5 degrees Celsius and the humidity not lower than 90%, for four hours to quickly improve strength and avoid frost damage. During the curing period, any disturbance to the pole, such as climbing or hanging heavy objects, is prohibited to ensure the stable formation of the reinforcement layer.

[0043] Step Six: Quality Inspection and Acceptance This final step involves visual inspection to ensure the reinforced layer surface is free of cracks, honeycombing, and exposed reinforcement, with a flatness error not exceeding 5 mm per meter. Strength testing utilizes the rebound method with a UHPC-specific rebound curve, or drills a 50 mm diameter core sample to test compressive strength, requiring a minimum of 120 MPa. Adhesion testing is conducted through pull-out tests at at least three points, with the interface bond strength needing to reach at least 3 MPa. For critical poles such as 500 kV lines, load tests are performed to measure bending capacity, requiring a recovery to at least 110% of the original design value, thus comprehensively verifying the reinforcement effect.

[0044] In summary, the key technical features of this method include interface synergistic reinforcement technology. Through dual treatment of epoxy interface agent and rebar anchoring, the bonding strength between the UHPC reinforcement layer and the original pole reaches over 3 MPa, far exceeding existing technologies, ensuring synergistic stress distribution. The optimized design of the UHPC material, by adjusting the steel fiber volume fraction to 2% and the silica fume content to 20%, gives the material high compressive strength of no less than 120 MPa, high flexural strength of no less than 15 MPa, and high durability, with a permeability coefficient not exceeding 1 x 10^-12 meters per second, adapting to the multi-dimensional stress requirements of the pole. The differentiated reinforcement scheme adjusts the thickness of the UHPC reinforcement layer according to the severity of the damage and adds additional longitudinal reinforcement or stirrups to avoid over- or under-reinforcement, balancing effectiveness and cost. The convenient construction process uses customized steel formwork and on-site mixing and pouring, with a construction cycle of no more than two days and power outage time of no more than one day, adapting to narrow construction spaces in the field and reducing the impact on power supply. UHPC's adaptability to all environments enables it to have an antifreeze rating of F300 and a chloride ion penetration resistance rating of RCMⅠ, allowing it to operate stably in environments ranging from -30°C to 60°C, coastal salt spray, and industrial corrosion, with a durability life of no less than 30 years.

[0045] Example 2 This embodiment applies the proposed method to a 110kV transmission line concrete pole in a coastal city. The pole, 22 years old, is 12m long, Φ300mm in diameter, and uses C30 concrete. Longitudinal cracks, 0.6-0.8mm wide, exist in the 0-3m height section of the pole. The steel reinforcement corrosion rate is 18%, and the chloride ion penetration depth is 15mm, classifying it as moderate damage. The requirement is that after reinforcement, the pole's bending capacity should be restored to at least 110% of the original design value of 120kN·m, its durability should meet the requirements of coastal salt spray environments, and the power outage time during construction should be ≤1 day.

[0046] The specific implementation plan includes the structural parameters for reinforcement and key construction steps. Regarding the reinforced structure, this embodiment uses a 70 mm thick UHPC reinforcement layer, with a material grade of C120, a steel fiber volume fraction of 2%, and a permeability coefficient not exceeding 1e-12 m / s. An epoxy interface agent with a bond strength of 4.2 MPa is used for interface treatment, combined with rebar anchoring. Φ10 HRB400E steel bars are used, spaced 180 mm apart, and embedded to a depth of 100 mm. Six additional Φ14 HRB400E steel bars are used as additional longitudinal reinforcement, evenly arranged along the circumference and welded to the original reinforcement bars, with a weld length of 140 mm. Φ6 HPB300 steel bars are used as annular stirrups, spaced 120 mm apart, and tied to the additional longitudinal reinforcement.

[0047] In this construction procedure, the surface is first treated by cleaning with a high-pressure water gun and then roughening it with a pneumatic chisel to a depth of 5 mm. Debris in cracked areas is blown away with high-pressure air. The diameter of the anchoring holes is 14 mm, and epoxy mortar with a compressive strength of 65 MPa is injected into the holes. After the rebar is inserted, it is cured for 24 hours. UHPC is prepared according to the following ratio: cement, silica fume, quartz sand, steel fiber, water-reducing agent, and water in a ratio of 1:0.2:1.2:0.02:0.02:0.16. After on-site mixing, the fluidity is 260 mm, and the initial setting time is 2.5 hours. Pouring is done by pumping at a pressure of 0.6 MPa. After compaction by vibration, it is covered with geotextile and cured for 7 days while maintaining an ambient temperature between 15 and 25 degrees Celsius.

[0048] The implementation results show that, in quality inspection, the UHPC surface had no cracks, the flatness error was 3 mm per meter, the core sample compressive strength reached 128 MPa, and the interface bond strength was 3.5 MPa. In the load-bearing capacity test, when horizontally loaded to 55 kN, the maximum deflection of the pole was 18 mm, less than or equal to 60 mm (pole length divided by 200), and the bending load-bearing capacity was 135 kNm, reaching 112.5% ​​of the original design value. Durability verification was conducted through a 1000-hour salt spray test using a 5% sodium chloride solution. The UHPC layer showed no corrosion, the interface showed no peeling, and the steel reinforcement corrosion rate was less than 0.5%. In terms of economics, the reinforcement cost of a single pole was 12,000 yuan, saving 40% compared to the 20,000 yuan for a newly built pole, and the maintenance cost over the entire 30-year lifespan was less than 1,000 yuan.

[0049] Example 3 This embodiment applies the proposed method to a 220kV transmission line in a frigid region. The concrete pole, 15 meters long and 350 mm in diameter, has been in service for 18 years. The original concrete strength grade was C30, but current testing indicates it is C20. Transverse cracks exist between 0 and 4 meters in height, with widths ranging from 1.2 to 1.5 mm. Concrete spalling area reaches 20%, and the steel reinforcement corrosion rate is 28%. The pole is classified as severely damaged. Reinforcement requirements include a frost resistance grade of at least F300, a flexural bearing capacity of at least 180 kNm, and a construction period not exceeding 2 days.

[0050] The reinforcement structural parameters used in this embodiment include a UHPC reinforcement layer thickness of 90 mm, a material grade of C150, and the addition of 5% antifreeze agent, resulting in a frost resistance grade of F300. Interface treatment utilizes an epoxy interface agent and rebar anchoring. The rebar anchoring uses Φ12 HRB400E steel bars, spaced 150 mm apart, with an embedment depth of 120 mm. Additional longitudinal reinforcement consists of 8 Φ16 HRB400E steel bars, welded to the original reinforcement. Circular stirrups are Φ8 HPB300 steel bars, spaced 100 mm apart, to enhance shear resistance.

[0051] In this embodiment, the surface treatment includes removing spalled concrete to a depth of 20 to 30 mm, roughening the surface to a solid base to a depth of 6 mm, and curing for 24 hours after rebar installation. Antifreeze is added during UHPC preparation, resulting in a flowability of 250 mm and an initial setting time of 2.2 hours. Pouring and curing are carried out at an ambient temperature of -5 degrees Celsius, using steam curing at 60 degrees Celsius for 4 hours. After curing, a 50 mm thick layer of insulation cotton is used to prevent frost damage.

[0052] In implementing key steps, UHPC material quality control includes incoming raw material inspection, requiring cement strength of no less than 52.5 MPa, silica fume reactive silica of no less than 95%, and steel fiber tensile strength of no less than 2800 MPa. Mixing control requires a total mixing time of no less than 7 minutes, steel fiber agglomeration rate of no more than 5%, and flowability deviation of no more than 10 mm. Strength testing requires the preparation of 3 sets of cubic test blocks per batch, with dimensions of 100 mm x 100 mm x 100 mm. After 28 days of standard curing, compressive strength is tested, and the results must reach or exceed the design value. In interface treatment quality control, the roughening depth is randomly measured at 10 points using a depth gauge, with an average depth of no less than 5 mm and a minimum depth of no less than 3 mm. For rebar pull-out tests, one rebar out of every 50 rebars is randomly selected, with a pull-out force of no less than 50 kN. For Φ10 rebars, double retesting is required if the test fails. Construction safety control includes workers wearing safety belts during high-altitude operations, and the use of insulated materials for the work platform to withstand the electrical environment. Power outage work must strictly follow the procedures of power outage, voltage testing, and grounding, and a safety warning zone with a radius of 10 meters must be set up. During winter construction, if the ambient temperature is below 5 degrees Celsius, steam curing shall be used to prevent UHPC from freezing, and the temperature during the curing period shall not be lower than 5 degrees Celsius.

[0053] In terms of implementation results, quality testing showed that the UHPC compressive strength was 155 MPa and the interfacial bond strength was 3.8 MPa; after F300 freeze-thaw cycles, the strength loss rate was less than 5%. In the load-bearing capacity test, the flexural capacity reached 205 kNm, meeting the design requirement of not less than 180 kNm. Construction efficiency was high, with the reinforcement of a single pole completed within 2 days, and the power outage time only 1 day, without affecting the power supply to the line.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A concrete pole reinforcement structure based on UHPC, characterized in that, The utility model relates to a kind of concrete pole, including: Original concrete pole; Interface treatment layer, the interface treatment layer includes epoxy interface agent coated on the surface of original concrete pole and embedded bar implanted in original concrete pole; UHPC reinforcing layer, wrapped in the outside of the original concrete pole, and bonded with the interface treatment layer; Optionally, including additional longitudinal reinforcement and ring hoop, the additional longitudinal reinforcement is uniformly arranged along the circumference of electric pole and extends into the UHPC reinforcing layer, and the ring hoop is around the additional longitudinal reinforcement and is tied with the additional longitudinal reinforcement.

2. The reinforcement structure of claim 1, wherein The bonding strength of the epoxy interface agent is not less than 4 MPa, and the solid content is not less than 90%.

3. The reinforcement structure of claim 1, wherein The embedded bar uses HRB400E grade steel bar, the diameter is Φ8-12mm, the implantation depth is 80-120mm, and the interval is 150-200mm.

4. The reinforcement structure of claim 1, wherein The material strength grade of the UHPC reinforcing layer is C120-C150, the compressive strength is not less than 120 MPa, the bending strength is not less than 15 MPa, the permeability coefficient is not greater than 1*10 -12 m / s, and the frost resistance grade is not less than F300; The thickness of the UHPC reinforcing layer is determined according to the degree of disease, when the mild disease, the crack width is less than 0.5mm, the thickness is 50mm; when the moderate disease, the crack width is 0.5-1.0mm, the thickness is 60-80mm; when the severe disease, the crack width is greater than 1.0mm, the thickness is 80-100mm.

5. The reinforcement structure of claim 1, wherein The additional longitudinal reinforcement uses HRB400E grade steel bar, the diameter is Φ12-16mm, the number is 4-8, and is uniformly arranged along the circumference of electric pole and welded with the original rod steel bar; The ring hoop uses HPB300 grade steel bar, the diameter is Φ6-8mm, the interval is 100-150mm, and is tied with the additional longitudinal reinforcement.

6. A method for reinforcing a concrete pole based on UHPC, characterized in that, The utility model relates to a kind of concrete pole, including: The following steps are included: Step one: nondestructive testing is carried out on the original concrete pole to determine the concrete strength, crack width and steel bar corrosion rate; Step two: high-pressure water cleaning, chiseling treatment and embedded bar construction are carried out on the surface of the original rod; Step three: a customized mold is installed, the mold is a semicircular steel mold, and an inlet and an exhaust port are provided; Step four: UHPC material is prepared and poured into the customized mold, and is vibrated and compacted to build a UHPC reinforcing layer; Step five: the UHPC reinforcing layer is maintained; 7. The method of reinforcement of claim 6, wherein, Step six: the appearance, strength, adhesion and bearing capacity of the reinforced concrete pole are tested.

8. The method of reinforcement of claim 6, wherein, In step two, the chiseling depth is not less than 5mm, and the surface roughness is not less than 2mm;Epoxy mortar is injected into the embedded bar hole, and the compressive strength is not less than 60MPa. In step four, the proportioning of UHPC material includes: Cement: silica fume: quartz sand: steel fiber: water reducing agent: water = 1:0.2:1.2:0.02:0.02:0.16; 9. The method of reinforcement of claim 6, wherein, The initial fluidity is not less than 250mm, and the initial setting time is not less than 2 hours. In step five, the maintenance methods include: Covering geotextile for moisture maintenance for 7 days in a normal temperature environment; 10. The method of reinforcement of claim 6, wherein, In a low temperature environment, steam curing is used, the temperature is controlled at 60±5℃, the humidity is not less than 90%, and the curing time is not less than 4 hours. In step six, the interface bonding strength of the adhesion test is not less than 3MPa, and the bending bearing capacity of the bearing capacity test is restored to more than 110% of the original design value.

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