Method for treating cracking of power transmission tower foundation by reducing upward pulling force

Abstract

The invention discloses a method for treating cracking of a power transmission tower foundation by reducing uplift force. The method comprises the following steps: building an uplift-resistant foundation; processing a connecting plate; a protective cap of the cracked foundation is dismantled; welding the connecting plate and the tower foot plate; installing a temporary stay wire for controlling the safety of the iron tower; the cracked concrete is removed; pouring and curing concrete at the cracking part; dismantling the temporary stay wire; and pouring a concrete protective cap. According to the method for treating power transmission tower foundation cracking by reducing the upward pulling force, the upward pulling force acting on the foundation is reduced, and cracked concrete is removed, so that the problem of foundation cracking is fundamentally solved.

Description

Technical Field

[0001] The invention relates to the field of transmission tower foundation reinforcement and treatment, in particular to a method for treating cracks in a transmission tower foundation by reducing upward pulling force. Background Art

[0002] Reinforced concrete is one of the most widely used building materials at present, and is widely used in power transmission lines, buildings, bridges and other projects. Due to the low tensile strength of concrete, cracking often occurs in concrete structures, that is, various cracks are formed on the surface of concrete structures, and the reinforced concrete foundation of overhead power transmission line towers is no exception. At present, the common methods for dealing with concrete cracks are mainly grouting (adding concrete sealant to the inside of the cracks) and surface sealing (pasting a single layer of carbon fiber cloth or other anti-cracking fiber mesh on the outer surface). The grouting method and the surface sealing method are both to seal the crack surface; for the problem of internal steel corrosion caused by concrete cracking, the method adopted is to chisel out the concrete matrix of the cracked part, replace the corroded steel with new steel bars, brush off the dust and debris from the chiseled part with a brush, rinse and moisten it with water, and finally fill and compact it with repair mortar.

[0003] Specific similar schemes are as follows: CN202323316807, discloses a concrete crack repair structure, which supports the inside of the crack and is used in conjunction with the grouting method, thereby greatly reducing the impact of wall stress on the newly filled concrete. CN202410441303, proposes a crack self-repair capsule that is highly compatible with concrete materials. The capsule core material contains a fast-response functional ratio component. The multiple components have a synergistic effect in the cracks, effectively improving the strength and service life of the concrete. CN202410723319, invented a crack-proof and impermeable concrete formula that does not require the addition of expansion agents and polypropylene fibers, avoids the inability to control the expansion rate, reduces the risk of temperature stress concentration and chemical shrinkage, and the new formula can effectively improve the crack resistance and reduce the risk of early concrete cracking. The composite material in its formula can significantly improve the durability, water penetration resistance and sulfate erosion resistance of the concrete. CN118754554, relates to a clear water concrete repair material and a clear water concrete repair method, wherein the clear water concrete repair material comprises a clear water concrete repair material matrix and a colorant, and can effectively restore the texture and color of the original clear water concrete. CN202410170489, a structure and method for improving the bonding performance of the concrete repair interface by carbonization, comprising a concrete matrix to be repaired, a cement-based repair material layer containing a solid carbon carrier, and an ordinary cement-based repair material layer, wherein the cement-based repair material layer containing a solid carbon carrier is located between the concrete matrix to be repaired and the ordinary cement-based repair material layer.

[0004] Whether it is crack filling, crack sealing, or changing the performance of concrete materials, the risk of cracking during the curing period or early service period can be reduced. The main features of these technologies are to fill or seal cracks, or to avoid the generation of non-load cracks, and to prevent air, water and other substances from invading the reinforced concrete through cracks. However, these methods only repair cracks and cannot change the nature of the cracking of the reinforced concrete foundation of the overhead transmission line tower due to excessive uplift force. The repaired concrete may crack again under external loads.

[0005] The existing method of reducing the uplift force to control the cracking of the transmission tower foundation is mainly to make advance arrangements during the construction of the iron tower. When repairing the cracking problem of the foundation of the existing transmission tower in operation, when the foundation of the transmission tower that has been formed and in operation cracks, there are the following problems: 1) The existing method of controlling the uplift of the iron tower is to install a guy wire on the iron tower. Because the guy wire must be at a certain angle with the tower body, it occupies a large space and requires new land acquisition, resulting in high cost and difficulty in land acquisition for installing the guy wire. 2) The method of controlling the uplift of the foundation includes inserting anchor rods around the foundation and connecting the anchor rods to the foundation during the pouring of concrete. The anchor rods resist the uplift by firmly anchoring in the rock, which is not applicable to the iron tower foundation with thick soil layer and deep rock buried. Moreover, the current method of controlling the uplift does not involve the removal and repair of the foundation cracks. Therefore, it is necessary to propose a method that does not require additional land acquisition, is suitable for geological conditions with thick soil layer, reduces the uplift force acting on the foundation of the transmission tower, and solves the problem of foundation cracking. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method for treating cracks in the foundation of a transmission tower by reducing the upward pull force, thereby fundamentally solving the problem of foundation cracks by reducing the upward pull force acting on the foundation and removing cracked concrete.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] A method for treating cracks in a transmission tower foundation by reducing the upward pull force comprises the following steps:

[0009] Step 1: Build an anti-uplift foundation;

[0010] Step 2: Processing the connecting plate;

[0011] Step 3: Remove the protective cap of the cracked foundation;

[0012] Step 4: Weld the connecting plate and the tower base plate;

[0013] Step 5: Install temporary guy wires to control the safety of the tower;

[0014] Step 6: Remove cracked concrete;

[0015] Step 7: Concrete pouring and curing of cracked parts;

[0016] Step 8: Remove the temporary pull wire;

[0017] Step 9: Pour the concrete protective cap.

[0018] In the step 1, constructing an anti-uplift foundation specifically includes:

[0019] The foundation with cracked concrete is defined as the cracked foundation, the two foundations adjacent to the cracked foundation are defined as the first uncracked foundation, and the foundation on the same diagonal line as the cracked foundation is defined as the second uncracked foundation;

[0020] Based on the line's advancing direction, an anti-uplift foundation is built at a certain inclination angle clockwise and at a certain distance from the center of the cracked foundation;

[0021] Bolts are reserved on the upper part of the two anti-uplift foundations to connect the connecting plate to the new foundation repaired on the cracked foundation.

[0022] In the step 2, processing the connecting plate specifically includes:

[0023] The steel plate with the same thickness as the tower base plate is cut into two connecting plates with the same structural dimensions. One end of each connecting plate is cut to form a notch end, which is matched and aligned with the two adjacent edges of the tower base plate. The other end of each connecting plate is a straight end with bolt holes processed at the straight end.

[0024] In the step three, the protective cap of the cracked foundation is removed, specifically including: removing the protective cap on the upper part of the tower foot plate by manual non-explosive means, and cleaning up the concrete fragments, dust and corrosion layer around the tower foot plate to ensure that the tower foot plate and the connecting plate are firmly welded.

[0025] In the step 4, welding the connecting plate and the tower base plate specifically includes: aligning the cut end of one of the connecting plates with the two sides of the tower base plate, welding and fixing, and fixing the straight end of the connecting plate to one of the anti-uplift foundations with bolts; aligning the cut end of the other connecting plate with the other two sides of the tower base plate, welding and fixing, and fixing the straight end of the other connecting plate to the other anti-uplift foundation with bolts.

[0026] In the step five, temporary guy wires are installed to control the safety of the iron tower, specifically including: installing temporary guy wires on the main material of the iron tower connected to the second uncracked foundation, the temporary guy wires are led to the outside of the tower body at a certain angle to the advancing direction of the line, the upper part of the temporary guy wires is fixed at the intersection of the main material and the cross arm, and the lower part of the temporary guy wires is fixed to the ground by ground anchors.

[0027] In the step six, the cracked concrete is removed, specifically including: manually chiseling away the cracked concrete from the outer edge of the cracked foundation to the tower foot plate in the horizontal direction and from top to bottom in the vertical direction, and cleaning the exposed uncracked concrete surface.

[0028] In the step seven, the cracked part is poured with concrete and cured, and the specific process includes: according to the size of the cracked foundation, formwork is supported around the cracked foundation, concrete with a higher grade than the cracked concrete is used, the cracked part removed from the cracked foundation is re-poured, and the formwork is removed after the prescribed curing is completed.

[0029] In the step eight, the temporary guy wire is removed, which specifically includes: first removing the fixed end of the temporary guy wire on the main material, then removing the fixed end of the temporary guy wire on the ground anchor, and finally removing the ground anchor.

[0030] In the step nine, a concrete protective cap is cast, and the specific process includes: casting a concrete protective cap on the anti-uplift foundation and the cracking foundation to ensure that the bolts of the connecting plate and the tower foot plate can be sealed inside the protective cap and are not exposed.

[0031] The present invention provides a split solid spiral structure, which has the following technical effects:

[0032] 1) Not only the cracked parts of the reinforced concrete foundation of the overhead transmission line tower are repaired, but also the uplift force acting on the foundation is reduced by building an anti-uplift foundation, avoiding secondary cracking of the foundation, achieving the effect of treating both the symptoms and the root cause.

[0033] 2) In step five, during the process of clearing and repairing the cracked parts of the foundation, the anti-uplift foundation and the temporary guy wire installed to control the safety of the tower ensured the safety and reliability of the construction process.

[0034] 3) In step 1, the anti-uplift foundation is set at a 45° inclination angle on both sides of the cracked foundation 2. The purpose is: if the first uncracked foundation and the second uncracked foundation have cracked or cracked later, the anti-uplift foundation can be used to control the uplift force of the first uncracked foundation and the second uncracked foundation. Assuming that the center distance between the four tower foundations is D, the distance of the anti-uplift foundation is

[0035] The buried depth is H and the cross-sectional dimensions are d×d, which meet the following conditions:

[0036]

[0037] Where: T b To reduce the pull-out force by 1 / 2; γ c is the horizontal force influence coefficient; cis the influence coefficient of the base development angle; A1, A2, A3 are dimensionless calculation coefficients, which are related to the sliding form of the anti-lift soil, the internal friction angle, and the foundation depth-to-diameter ratio; c is the soil cohesion; γ s is the weighted average weight of the soil above the foundation bottom; H ​​is the foundation burial depth, which is less than the limit depth of the shear failure mode; V0 is the volume within the foundation burial depth range, which is related to the foundation section size d×d and the burial depth H; G f It is the deadweight of the foundation, which is related to the foundation section size d×d and the burial depth H. K1 and K2 are the foundation pull-out safety factors.

[0038] 4) In step 4, the anti-uplift foundation is connected to the cracked foundation 2 by setting the connecting plate 4, so as to achieve the purpose of transmitting and reducing the uplift force acting on the cracked foundation 2. Considering that the tower foot plate is fixedly connected to the cracked foundation 2 by bolts, affected by the existing bolts and other steel plates vertically welded to the tower foot plate, there is no welding surface on the end face of the tower foot plate, and the connecting plate 4 is not convenient to overlap on the tower foot plate, so the connecting plate 4 is welded to the edge of the tower foot plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0040] Figure 1 This is the orientation diagram of the anti-uplift foundation and temporary tension wire.

[0041] Figure 2 Layout diagram of cracked foundation and anti-uplift foundation

[0042] Figure 3 It is a top view of the connecting plate in the present invention.

[0043] Figure 4 Temporary guy wire arrangement diagram for controlling tower safety.

[0044] Figure 5 Schematic diagram of the damage factor changing with the pull-out load.

[0045] Figure 6 This is the damage cloud diagram of the top surface of the foundation with 100% pull-out load.

[0046] In the figure: cracked concrete 1, cracked foundation 2, anti-uplift foundation 3, connecting plate 4, first uncracked foundation 5, second uncracked foundation 6, bolt hole 7, ground anchor 8, temporary guy wire 9, straight end 10, cut end 11, line forward direction X. DETAILED DESCRIPTION

[0047] like Figure 1-4 As shown, a method for treating cracks in a transmission tower foundation by reducing the upward pull force comprises the following steps:

[0048] Step 1: Build an anti-uplift foundation;

[0049] Step 2: Processing the connecting plate;

[0050] Step 3: Remove the protective cap of the cracked foundation;

[0051] Step 4: Weld the connecting plate and the tower base plate;

[0052] Step 5: Install temporary guy wires to control the safety of the tower;

[0053] Step 6: Remove cracked concrete;

[0054] Step 7: Concrete pouring and curing of cracked parts;

[0055] Step 8: Remove the temporary pull wire;

[0056] Step 9: Pour the concrete protective cap.

[0057] In step one, an anti-uplift foundation is constructed, and the specific process includes: the foundation with cracked concrete 1 is the cracked foundation 2, and the other three foundations are: the two adjacent to the cracked foundation 2 are the first uncracked foundation 5, and the second uncracked foundation 6 on the same diagonal as the cracked foundation 2. On both sides of the cracked foundation 2, with the line advancing direction as the reference, in a direction with an inclination angle of 45° clockwise, at a distance of L from the center of the cracked foundation 2, an anti-uplift foundation 3 with a buried depth of H and a cross-sectional size of d×d is constructed, and H and d are both 1 / 2 of the cross-sectional size of the cracked foundation 2, or are determined according to actual engineering requirements and mechanical calculations; 4 bolts are pre-embedded in the upper part of the two anti-uplift foundations 3, which are used to connect the connecting plate 4 to the new foundation repaired on the cracked foundation 2.

[0058] In step 2, the connection plate is processed. The specific process includes: the tower foot plate has a thickness of c and a square cross section with a side length of a; the steel plate with the same thickness as the tower foot plate is cut into two connection plates 4, the two connection plates 4 have the same structural dimensions, and each connection plate 4 has a length of b and a width of One end of each connecting plate 4 is cut off into an isosceles right triangle with a side length a according to the size of the tower foot plate to form a cut end 11, and the other end is a straight end 10, and four bolt holes 7 are processed at the straight end 10.

[0059] In step three, the protective cap of the cracked foundation is removed. The specific process includes: removing the protective cap on the upper part of the tower foot plate by manual non-explosive means, and cleaning the concrete fragments, dust and corrosion layer around the tower foot plate to ensure that the tower foot plate and the connecting plate 4 are firmly welded.

[0060] In step four, the connecting plate and the tower base plate are welded, and the specific process includes: aligning the cut end 11 of one of the connecting plates 4 with the two sides of the tower base plate, welding and fixing it, and using bolts to fix the straight end 10 of the connecting plate 4 to one of the anti-uplift foundations 3; using the same method, aligning the cut end 11 of the other connecting plate 4 with the other two sides of the tower base plate, welding and fixing it, and using bolts to fix the straight end 10 of the other connecting plate 4 to the other anti-uplift foundation 3.

[0061] In step five, temporary guy wires are installed to control the safety of the iron tower. The specific process includes: installing temporary guy wires 9 on the main material of the iron tower connected to the second uncracked foundation 6, the temporary guy wires 9 are led to the outside of the tower body at an angle of 45° to the forward direction of the line, the upper part of the temporary guy wires 9 is fixed at the intersection of the main material and the cross arm, and the lower part of the temporary guy wires 9 is fixed to the ground through anchors 8 to ensure the stability of the iron tower when the cracked concrete 1 is removed.

[0062] In step six, the cracked concrete is removed. The specific process includes: manually chiseling away the cracked concrete 1 from the outer edge of the foundation to the tower foot plate in the horizontal direction and from top to bottom in the vertical direction, and cleaning the exposed uncracked foundation concrete surface.

[0063] In step seven, the cracked part is poured with concrete and cured. The specific process includes: according to the size of the cracked foundation 2, a formwork is supported around the cracked foundation 2, and concrete with a grade higher than that of the cracked concrete 1 is used to re-pour the cracked part of the cracked foundation 2 that has been removed, and the formwork is removed after the prescribed curing is completed.

[0064] In step eight, the temporary guy wire is removed. The specific process includes: firstly removing the fixed end of the temporary guy wire 9 on the main material, then removing the fixed end of the temporary guy wire 9 on the anchor 8, and finally removing the anchor 8.

[0065] In step nine, a concrete protective cap is poured, and the specific process includes: pouring a concrete protective cap on the anti-uplift foundation 3 and the crack foundation 2 to ensure that the bolts of the connecting plate 4 and the tower foot plate can be sealed inside the protective cap without being exposed.

[0066] The present invention has been verified through simulation and the expected effect is consistent.

[0067] Depend on Figure 5 As shown in Table 1, the maximum value of the damage factor increases with the increase of the pull-out load, and once the pull-out load reaches 95% of the design load, the maximum value of the damage factor will suddenly change from 0.28 under the previous load level to 0.61, indicating that the foundation begins to crack at this time. The damage cloud diagram of the foundation top surface at 100% pull-out load is as follows: Figure 6This shows that the pull-out load is the main factor affecting the cracking of the upper part of the foundation. By reducing the upper load acting on the foundation, the problem of foundation cracking can be fundamentally solved.

[0068] Table 1 Maximum damage factors under different pull-out loads

[0069]

Claims

1. A method for treating cracks in a transmission tower foundation by reducing the upward pull force, comprising the following steps: Step 1: Build an anti-uplift foundation; Step 2: Processing the connecting plate; Step 3: Remove the protective cap of the cracked foundation; Step 4: Weld the connecting plate and the tower base plate; Step 5: Install temporary guy wires to control the safety of the tower; Step 6: Remove cracked concrete; Step 7: Concrete pouring and curing of cracked parts; Step 8: Remove the temporary pull wire; Step 9: Pour the concrete protective cap.

2. A method for treating cracks in a transmission tower foundation by reducing the upward pull force according to claim 1, characterized in that: In the step 1, constructing an anti-uplift foundation specifically includes: The foundation with cracked concrete (1) is defined as a cracked foundation (2), two foundations adjacent to the cracked foundation (2) are defined as a first uncracked foundation (5), and a foundation on the same diagonal line as the cracked foundation (2) is defined as a second uncracked foundation (6); Based on the line advancing direction, an anti-uplift foundation (3) is constructed at a certain inclination angle clockwise and at a certain distance from the center of the cracked foundation (2); Bolts are reserved on the upper parts of the two anti-uplift foundations (3) for connecting the connection plate (4) to the new foundation repaired on the cracked foundation (2).

3. The method for treating cracks in the foundation of a transmission tower by reducing the upward pull force according to claim 1, characterized in that: In the step 2, processing the connecting plate specifically includes: A steel plate having the same thickness as the tower foot plate is cut into two connecting plates (4), the two connecting plates (4) having the same structural dimensions, one end of each connecting plate (4) is cut to form a notch end (11), the notch end (11) matches and is aligned with two adjacent edges of the tower foot plate, the other end of each connecting plate (4) is a straight end (10), and a bolt hole (7) is processed at the straight end (10).

4. The method for treating cracks in the foundation of a transmission tower by reducing the upward pull force according to claim 1, characterized in that: In the step 3, the protective cap of the cracked foundation is removed, which specifically includes: removing the protective cap on the upper part of the tower foot plate by artificial non-explosive means, and cleaning the concrete fragments, dust and corrosion layer around the tower foot plate to ensure that the tower foot plate and the connecting plate (4) are firmly welded.

5. The method for treating cracks in the foundation of a transmission tower by reducing the upward pull force according to claim 1, characterized in that: In the step 4, the connection plate and the tower foot plate are welded, specifically comprising: aligning the cut end (11) of one of the connection plates (4) with the two sides of the tower foot plate, welding and fixing, and fixing the straight end (10) of the connection plate (4) with one of the anti-uplift foundations (3) using bolts; aligning the cut end (11) of the other connection plate (4) with the other two sides of the tower foot plate, welding and fixing, and fixing the straight end (10) of the other connection plate (4) with the other anti-uplift foundation (3) using bolts.

6. The method for treating cracks in the foundation of a transmission tower by reducing the upward pull force according to claim 1, characterized in that: In the step 5, a temporary guy wire for controlling the safety of the iron tower is installed, which specifically includes: installing a temporary guy wire (9) on the main material of the iron tower connected to the second uncracked foundation (6), the temporary guy wire (9) is led to the outside of the tower body at a certain angle to the advancing direction of the line, the upper part of the temporary guy wire (9) is fixed at the intersection of the main material and the cross arm, and the lower part of the temporary guy wire (9) is fixed to the ground through a ground anchor (8).

7. The method for treating cracks in the foundation of a transmission tower by reducing the upward pull force according to claim 1, characterized in that: In the step six, the cracked concrete is removed, specifically comprising: manually chiseling away the cracked concrete (1) from the outer edge of the cracked foundation (2) to the tower foot plate in the horizontal direction and from top to bottom in the vertical direction, and cleaning the exposed uncracked concrete surface.

8. The method for treating cracks in the foundation of a transmission tower by reducing the upward pull force according to claim 1, characterized in that: In step seven, the cracked part of the concrete is poured and cured, and the specific process includes: according to the size of the cracked foundation (2), a formwork is supported around the cracked foundation (2), and concrete of a higher grade than the cracked concrete (1) is used to re-pour the cracked part of the cracked foundation (2) that has been removed, and the formwork is removed after the prescribed curing is completed.

9. The method for treating cracks in the foundation of a transmission tower by reducing the upward pull force according to claim 1, characterized in that: In the step eight, the temporary pull wire is removed, which specifically includes: first removing the fixed end of the temporary pull wire (9) on the main material, then removing the fixed end of the temporary pull wire (9) on the anchor, and finally removing the anchor (8).

10. The method for treating cracks in the foundation of a transmission tower by reducing the upward pull force according to claim 1, characterized in that: In the step nine, a concrete protective cap is cast, and the specific process includes: casting a concrete protective cap on the anti-uplift foundation (3) and the crack foundation (2) to ensure that the bolts of the connecting plate (4) and the tower foot plate can be sealed inside the protective cap and are not exposed.

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