Construction method for post-anchoring variable-diameter anchor bolt of existing concrete structure

Abstract

The invention provides a construction method for post-anchoring a variable-diameter anchor bolt in an existing concrete structure, which comprises the following steps of: according to design drawing requirements and a finite element analysis result, performing paying-off positioning in the existing concrete structure by adopting a corresponding variable-diameter anchor bolt, and drilling by adopting a percussion drill provided with a variable-diameter drill rod to form a steel bar planting hole; in the step, the basic anchoring depth ls'of the variable-diameter embedded steel bar is calculated according to the basic anchoring depth ls of the embedded steel bar; after the holes are formed, the hole walls of the steel bar planting holes are brushed with a scrubbing brush or a hard nylon brush, dust in the steel bar planting holes is blown away with compressed air, and the steel bar planting holes are washed with water; chemical glue or chemical mortar is injected into the steel bar planting holes through a glue injector; and the inserting part where the variable-diameter anchor bolt needs to be planted is brushed clean through a steel wire brush, then is slowly rotated and inserted into the steel bar planting hole, and is kept still until the glue is cured. According to the construction method for post-anchoring the variable-diameter anchor bolt in the existing concrete structure, the steel consumption and the chemical glue consumption are less, the damage to the original structure is small, and the construction speed is high.

Description

Technical Field

[0001] The invention relates to the technical field of building construction, and in particular to a construction method for post-anchoring variable-diameter anchor bolts in an existing concrete structure. Background Art

[0002] Due to a series of reasons, the functionality, durability and structural seismic performance of houses in the past could not meet the needs of people's lives and the country's new seismic fortification; therefore, reinforcing and renovating old houses and strengthening their structures has become a key research direction in the current construction industry.

[0003] However, the current reinforcement and structural reinforcement technologies have the following defects:

[0004] (1) The connection between the new and old concrete surfaces relies more on the bonding force of concrete, which is not reliable;

[0005] (2) Adding steel structure supports and anchoring them will cause damage to the original structure;

[0006] (3) On-site construction is difficult, construction quality is difficult to control, and reinforcement costs are high;

[0007] (4) Chemical anchoring of equal diameter requires a large amount of steel and is difficult to drill in high-strength concrete, which can easily cause damage to the original structure. Summary of the invention

[0008] The invention provides a construction method for post-anchoring variable-diameter anchor bolts in existing concrete structures, which can effectively solve the problems of large amount of steel used for equal-diameter chemical anchoring, difficulty in drilling holes in high-strength concrete, and great damage to the original structure.

[0009] The technical solution adopted by the present invention is: a construction method for post-anchoring variable diameter anchor bolts in an existing concrete structure, comprising the following steps:

[0010] According to the requirements of the design drawings and the results of finite element analysis, the corresponding variable diameter anchor bolts are used to lay out and locate in the existing concrete structure, and an impact drill equipped with a variable diameter drill rod is used to drill holes to form rebar holes;

[0011] In this step, according to the basic anchoring depth l of the rebar, s Calculate the basic anchorage depth l of variable diameter rebar s’ , the calculation formula is as follows:

[0012] l s’ = l s1 +l s2

[0013] l s1 =α 1 l s

[0014] l s2 =α 2 l s

[0015] in,

[0016] l s =0.2α spt df y / f bd

[0017] l s1 ——The anchoring length of the front large diameter;

[0018] l s2 ——The anchoring length of the rear small diameter;

[0019] α 1 ——coefficient, the value range is 0.2~0.3;

[0020] α 2 ——coefficient, the value range is 0.7~0.8;

[0021] After the hole is formed, use a hard brush or a hard nylon brush to clean the wall of the hole for planting reinforcement. Use compressed air to blow away the dust in the hole and rinse with water. The hole for planting reinforcement should be 4 to 6 mm larger than the diameter of the steel bar.

[0022] Use a glue injector to inject chemical glue or chemical mortar into the rebar embedding hole, where the amount of glue injected is 2 / 3 of the hole depth;

[0023] Clean the insertion part of the variable diameter anchor bolt with a wire brush, then slowly rotate it into the anchor hole and keep it still until the glue solidifies.

[0024] Furthermore, after the position of the implanted variable diameter anchor is calibrated, it must be protected by a dedicated person within 30 minutes.

[0025] Furthermore, the method further comprises the following steps: after the variable diameter anchor bolt is implanted, a post-installed steel member is installed, and a washer and a nut provided with the variable diameter anchor bolt are screwed on.

[0026] The present invention further provides the following technical solution:

[0027] A construction method for post-anchoring variable diameter anchor bolts in an existing concrete structure comprises the following steps:

[0028] According to the requirements of the design drawings, the corresponding variable diameter anchor bolts are used to lay out and locate in the existing concrete structure, and the impact drill with a variable diameter drill rod is used to drill holes to form the rebar holes;

[0029] In this step, according to the basic anchoring depth l of the rebar, s Calculate the basic anchorage depth l of variable diameter rebars’ , the calculation formula is as follows:

[0030] l s’ = l s1 +l s2

[0031] l s1 =α 1 l s

[0032] l s2 =α 2 l s

[0033] Among them, l s =0.2α spt df y / f bd

[0034] l s1 ——The anchoring length of the front large diameter;

[0035] l s2 ——The anchoring length of the rear small diameter;

[0036] α 1 ——coefficient, value range 0.2~0.3;

[0037] α 2 ——coefficient, the value range is 0.7~0.8;

[0038] After the hole is formed, use a hard brush or a hard nylon brush to clean the wall of the hole for planting reinforcement. Use compressed air to blow away the dust in the hole for planting reinforcement and rinse with water. The hole for planting reinforcement should be 4 to 6 mm larger than the diameter of the steel bar.

[0039] Use a glue injector to inject chemical glue or chemical mortar into the rebar embedding hole, where the amount of glue injected is 2 / 3 of the hole depth;

[0040] Clean the insertion part of the variable diameter anchor bolt with a wire brush, then slowly rotate it into the anchor hole and keep it still until the glue solidifies;

[0041] After the variable diameter anchor bolt is implanted, the adjustment gasket is placed, and then the rear steel structure is installed, the washers and nuts provided with the variable diameter anchor bolt are screwed on, and finally the secondary grouting is carried out.

[0042] Furthermore, after the position of the implanted variable diameter anchor is calibrated, it needs to be protected by a dedicated person within 30 minutes.

[0043] The present invention also provides the following technical solutions:

[0044] A construction method for post-anchoring variable diameter anchor bolts in an existing concrete structure comprises the following steps:

[0045] According to the requirements of the design drawings, the surface of the existing concrete structure is roughened, the corresponding variable diameter anchor bolts are used to lay out and position the existing concrete structure, and an impact drill with a variable diameter drill rod is used to drill holes to form rebar holes;

[0046] In this step, according to the basic anchoring depth l of the rebar, s Calculate the basic anchorage depth l of variable diameter rebar s’ , the calculation formula is as follows:

[0047] l s’ = l s1 +l s2

[0048] l s1 =α 1 l s

[0049] l s2 =α 2 l s

[0050] Among them, l s =0.2α spt df y / f bd

[0051] l s1 ——The anchoring length of the front large diameter;

[0052] l s2 ——The anchoring length of the rear small diameter;

[0053] α 1 ——coefficient, the value range is 0.2~0.3;

[0054] α 2 ——coefficient, the value range is 0.7~0.8;

[0055] After the hole is formed, use a hard brush or a hard nylon brush to clean the wall of the hole for planting reinforcement. Use compressed air to blow away the dust in the hole for planting reinforcement and rinse with water. The hole for planting reinforcement should be 4 to 6 mm larger than the diameter of the steel bar.

[0056] Use a glue injector to inject chemical glue or chemical mortar into the rebar embedding hole, where the amount of glue injected is 2 / 3 of the hole depth;

[0057] Clean the insertion part of the variable diameter anchor bolt with a wire brush, then slowly rotate it into the anchor hole and keep it still until the glue solidifies.

[0058] Furthermore, after the position of the implanted variable diameter anchor is calibrated, it must be protected by a dedicated person within 30 minutes.

[0059] Furthermore, the method further comprises the following steps:

[0060] After the variable diameter anchor bolts are implanted, the surface of the existing concrete structure is washed and the interface agent is brushed on it. Then the vertical steel bars, stirrups and tension bars are tied and reinforced, the formwork is supported, and finally the micro-expansion concrete is poured.

[0061] Furthermore, before injecting glue, the rebar hole is kept dry.

[0062] Compared with the prior art, the construction method of the variable diameter anchor bolt for post-anchoring an existing concrete structure of the present invention uses a variable diameter drill rod to drill holes, and designs the variable diameter anchor bolt according to the size of the force, with a large front end force and a small rear end force, thereby achieving less steel and chemical glue usage, and the variable diameter anchor bolt causes less damage to the original structure and a faster construction speed, especially for existing concrete structures with higher concrete strength, the drilling speed of small diameter holes is faster and easier to construct. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but should not constitute a limitation of the present invention.

[0064] Figure 1 : Schematic diagram of the bonding between the steel bar and concrete of the present invention;

[0065] Figure 2 : A schematic diagram of the micro-segment force of the steel bar of the present invention;

[0066] Figure 3 : Schematic diagram of pile side friction distribution of the present invention;

[0067] Figure 4 : Schematic diagram of the tensile application of the variable diameter anchor bolt of the present invention implanted in an existing concrete structure;

[0068] Figure 5 : Schematic diagram of compression resistance application of variable diameter anchor bolts of the present invention implanted in existing concrete structures;

[0069] Figure 6 : Schematic diagram of the shear resistance application of the variable diameter anchor bolt of the present invention implanted in an existing concrete structure;

[0070] Figure 7 : A schematic structural diagram of a variable diameter drill rod of the present invention;

[0071] Figure 8 : Schematic diagram of experimental results of finite element analysis of pull-out resistance of variable diameter anchor bolts of the present invention;

[0072] Fig. 9 : Schematic diagram of another experimental result of the finite element analysis of the pull-out resistance of the variable diameter anchor bolt of the present invention;

[0073] Fig.10 : Another schematic diagram of experimental results of the finite element analysis of pull-out resistance of variable diameter anchor bolts of the present invention;

[0074] Fig.11 : Comparison table of results of finite element analysis of pull-out resistance of anchor bolts of the present invention. DETAILED DESCRIPTION

[0075] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0076] Embodiment 1

[0077] like Figures 1 to 4 As shown, this embodiment provides a tensile construction method for post-anchoring variable diameter anchor bolts in an existing concrete structure, comprising the following steps:

[0078] Step 1: According to the design drawing requirements and the finite element analysis results, the corresponding variable diameter anchor bolts 3 are used to lay out and position in the existing concrete structure 1, and the variable diameter drill rods 5 (such as Figure 7 The impact drill (shown) is used to drill holes to form reinforcing bar holes;

[0079] In this step, according to the basic anchoring depth l of the rebar, s Calculate the basic anchorage depth l of variable diameter rebar s’ , the calculation formula is as follows:

[0080] l s’ = l s1 +l s2

[0081] l s1 =α 1 l s

[0082] l s2 =α 2 l s

[0083] in,

[0084] l s1 ——The anchoring length of the front large diameter;

[0085] l s2 ——The anchoring length of the rear small diameter;

[0086] α 1 ——coefficient, the value range is 0.2~0.3, and a higher value is suitable when the diameter is larger;

[0087] α 2 ——coefficient, the value range is 0.7~0.8;

[0088] Among them, l s =0.2α spt df y / f bd

[0089] l s ——Basic anchorage depth of the rebar;

[0090] α spt - calculation coefficients used to prevent concrete splitting;

[0091] d——nominal diameter of the embedded reinforcement (mm);

[0092] f y ——Design value of tensile and compressive strength of ordinary steel bars;

[0093] f bd ——Design value of the bonding shear strength of the adhesive used for anchoring (N / mm 2 ).

[0094] Step 2: After the hole is formed, use a hard-bristle brush or a hard nylon brush to clean the hole wall of the rebar hole, blow away the dust in the hole with compressed air and rinse with water; the rebar hole should be 4 to 6 mm larger than the diameter of the steel bar.

[0095] Step 3: Use a glue injector to inject chemical glue 2 (or chemical mortar) into the rebar hole. The amount of glue injected is 2 / 3 of the hole depth, and it is appropriate to have a small amount of overflow after inserting the variable diameter anchor bolt 3. Before injecting glue, the rebar hole should be kept dry and glue should not be injected in a water environment.

[0096] Step 4: Brush the inserted part of the variable diameter anchor 3 with a wire brush, then slowly rotate it into the rebar hole and keep it still until the glue solidifies; after the position of the variable diameter anchor 3 is calibrated, it should be protected by a dedicated person within 30 minutes to prevent people, machinery, etc. from colliding with the variable diameter anchor 3 and affecting the tension effect; if welding is required, care should be taken to avoid the influence of high welding temperature on the strength of the chemical glue, and relevant protective measures should be taken for the chemical glue 2.

[0097] Step 5: After the variable diameter anchor bolt 3 is implanted, the rear steel member 4 is installed, and the washers and nuts provided with the variable diameter anchor bolt 3 are screwed on.

[0098] Embodiment 2

[0099] like Figures 1 to 3 as well as Figure 5 As shown, this embodiment provides a compression-resistant construction method for post-anchoring variable-diameter anchor bolts in an existing concrete structure, comprising the following steps:

[0100] Step 1: According to the design drawing requirements, the corresponding variable diameter anchor bolt 3 is used to lay out and locate in the existing concrete structure 1, and the variable diameter drill rod 5 (such as Figure 7 The impact drill (shown) is used to drill holes to form reinforcing bar holes;

[0101] In this step, according to the basic anchoring depth l of the rebar, s Calculate the basic anchorage depth l of variable diameter rebar s’ , the calculation formula is as follows:

[0102] l s’ = l s1 +l s2

[0103] l s1 =α 1 l s

[0104] l s2 =α 2 l s

[0105] in,

[0106] l s1 ——The anchoring length of the front large diameter;

[0107] l s2 ——The anchoring length of the rear small diameter;

[0108] α 1 ——coefficient, the value range is 0.2~0.3, and a higher value is suitable when the diameter is larger;

[0109] α 2 ——coefficient, the value range is 0.7~0.8;

[0110] Among them, l s =0.2α spt df y / f bd

[0111] l s ——Basic anchorage depth of the rebar;

[0112] α spt - calculation coefficients used to prevent concrete splitting;

[0113] d——nominal diameter of the embedded reinforcement (mm);

[0114] f y ——Design value of tensile and compressive strength of ordinary steel bars;

[0115] f bd——Design value of the bonding shear strength of the adhesive used for anchoring (N / mm 2 ).

[0116] Step 2: After the hole is formed, use a hard-bristle brush or a hard nylon brush to clean the hole wall of the rebar hole. Use compressed air to blow away the dust in the hole and rinse with water. The rebar hole should be 4 to 6 mm larger than the diameter of the steel bar.

[0117] Step 3: Use a glue injector to inject chemical glue 2 (or chemical mortar) into the rebar hole. The amount of glue injected should be 2 / 3 of the hole depth, and it is appropriate to have a small amount of overflow after inserting the variable diameter anchor bolt 3. Before injecting glue, the rebar hole should be kept dry and glue should not be injected in a water environment.

[0118] Step 4: Clean the insertion part of the variable diameter anchor bolt 3 with a wire brush, then slowly rotate it and insert it into the anchor hole, and keep it still until the glue solidifies; after the position of the variable diameter anchor bolt 3 is calibrated, it should be protected by a dedicated person within 30 minutes to prevent personnel, machinery, etc. from colliding with the anchor bolt and affecting the tension effect. If welding is required, care should be taken to avoid the influence of high welding temperature on the strength of the chemical glue, and take protective measures for the chemical glue.

[0119] Step 5: After the variable diameter anchor bolt 3 is implanted, the adjustment gasket 6 is placed, and then the rear steel member 4 is installed, and the gasket and nut provided with the variable diameter anchor bolt 3 are screwed on, and finally the secondary grouting 7 is performed.

[0120] Embodiment 3

[0121] like Figures 1 to 3 and Figure 6 As shown, this embodiment provides a shear-resistant construction method for post-anchoring variable-diameter anchor bolts in an existing concrete structure, comprising the following steps:

[0122] Step 1: According to the requirements of the design drawings, the surface of the existing concrete structure 1 is roughened, and the corresponding variable diameter anchor bolts 3 are used to lay out and position the existing concrete structure 1, and the variable diameter drill rod 5 (such as Figure 7 The impact drill (shown) is used to drill holes to form reinforcing bar holes;

[0123] In this step, according to the basic anchoring depth l of the rebar, s Calculate the basic anchorage depth l of variable diameter rebar s’ , the calculation formula is as follows:

[0124] l s’ = l s1 +l s2

[0125] l s1 =α 1 l s

[0126] l s2 =α 2 l s

[0127] in,

[0128] l s1 ——The anchoring length of the front large diameter;

[0129] l s2 ——The anchoring length of the rear small diameter;

[0130] α 1 ——coefficient, the value range is 0.2~0.3, and a higher value is suitable when the diameter is larger;

[0131] α 2 ——coefficient, the value range is 0.7~0.8;

[0132] Among them, l s =0.2α spt df y / f bd

[0133] l s ——Basic anchorage depth of the rebar;

[0134] α spt - calculation coefficients used to prevent concrete splitting;

[0135] d——nominal diameter of the embedded reinforcement (mm);

[0136] f y ——Design value of tensile and compressive strength of ordinary steel bars;

[0137] f bd ——Design value of the bonding shear strength of the adhesive used for anchoring (N / mm 2 ).

[0138] Step 2: After the hole is formed, use a hard-bristle brush or a hard nylon brush to clean the hole wall of the rebar hole. Use compressed air to blow away the dust in the hole and rinse with water. The rebar hole should be 4 to 6 mm larger than the diameter of the steel bar.

[0139] Step 3: Use a glue injector to inject chemical glue 2 (or chemical mortar) into the rebar hole. The amount of glue injected should be 2 / 3 of the hole depth, and it is appropriate to have a small amount of overflow after inserting the variable diameter anchor bolt 3. Before injecting glue, the rebar hole should be kept dry and glue should not be injected in a water environment.

[0140] Step 4: Clean the insertion part of the variable diameter anchor bolt 3 with a wire brush, then slowly rotate it and insert it into the anchor hole, and keep it still until the glue solidifies; after the position of the variable diameter anchor bolt 3 is calibrated, it should be protected by a dedicated person within 30 minutes to prevent personnel, machinery, etc. from colliding with the anchor bolt and affecting the tension effect. If welding is required, care should be taken to avoid the influence of high welding temperature on the strength of the chemical glue, and take protective measures for the chemical glue.

[0141] Step 5: After the variable diameter anchor bolts 3 are implanted, the surface of the existing concrete structure 1 is washed and the interface agent is brushed, and then the vertical steel bars, stirrups and tension bars are tied and reinforced, the formwork is supported, and finally the micro-expansion concrete 8 is poured.

[0142] like Figures 8 to 11 As shown, Figures 8 to 10 It is a schematic diagram of the experimental results of the finite element analysis of the pull-out resistance of the variable diameter anchor bolt of the present invention; Fig.11 This is a comparative result table of the pull-out finite element analysis of the variable diameter anchor bolt of the present invention; Figures 8 to 11 The results show that:

[0143] (1) The variable diameter anchor bolt 3 is designed according to the magnitude of the force, with a large front force and a small rear force, thereby achieving a smaller amount of steel and chemical glue.

[0144] (2) Compared with the existing post-anchor bolts of equal diameter, the variable diameter anchor bolts 3 have a faster construction speed, especially for existing concrete structures with greater concrete strength. The small diameter variable diameter drill rod 5 has a faster drilling speed and is easier to construct.

[0145] (3) Compared with the existing post-anchored anchor bolts with equal diameter, the variable diameter anchor bolt 3 causes less damage to the original structure.

[0146] In summary, the construction method of the variable diameter anchor bolt for post-anchoring of existing concrete structures of the present invention has the following advantages:

[0147] 1. Compared with the existing rear anchor bolts of equal diameter, it is more economical. The variable diameter anchor bolt is designed according to the force. The front end force is large and the rear end force is small, so that less steel and chemical glue are used.

[0148] 1. Compared with the existing post-anchor bolts of the same diameter, the construction speed is faster, especially for existing concrete structures with higher concrete strength, the drilling speed of small diameter is faster and easier to construct.

[0149] 2. Compared with the existing equal-diameter post-anchored anchor bolts, variable-diameter anchor bolts cause less damage to the original structure.

[0150] As long as it does not violate the creative ideas of the present invention, any combination of the various embodiments of the present invention shall be regarded as the contents disclosed by the present invention; within the technical concept of the present invention, any combination of various simple modifications of the technical scheme and different embodiments that does not violate the creative ideas of the present invention shall be within the protection scope of the present invention.

Claims

1. A construction method for post-anchoring variable diameter anchor bolts in an existing concrete structure, characterized in that: The following steps are involved: According to the requirements of the design drawings and the results of finite element analysis, the corresponding variable diameter anchor bolts are used to lay out and locate in the existing concrete structure, and an impact drill equipped with a variable diameter drill rod is used to drill holes to form rebar holes; In this step, according to the basic anchoring depth l of the rebar, s Calculate the basic anchorage depth l of variable diameter rebar s’ , the calculation formula is as follows: l s’ ＝l s1 +l s2 l s1 ＝α1l s l s2 ＝α2l s in, l s =0.2α spt df y / f bd l s1 ——The anchoring length of the front large diameter; l s2 ——The anchoring length of the rear small diameter; α1——coefficient, ranging from 0.2 to 0.3; α2——coefficient, ranging from 0.7 to 0.8; After the hole is formed, use a hard brush or a hard nylon brush to clean the wall of the hole for planting reinforcement. Use compressed air to blow away the dust in the hole and rinse with water. The hole for planting reinforcement should be 4 to 6 mm larger than the diameter of the steel bar. Use a glue injector to inject chemical glue or chemical mortar into the rebar embedding hole, where the amount of glue injected is 2 / 3 of the hole depth; Clean the insertion part of the variable diameter anchor bolt with a wire brush, then slowly rotate it into the anchor hole and keep it still until the glue solidifies.

2. The construction method of the variable diameter anchor bolt for post-anchoring of an existing concrete structure as claimed in claim 1, characterized in that: After the position of the implanted variable diameter anchor is calibrated, a dedicated person is required to provide protection within 30 minutes.

3. The construction method of the variable diameter anchor bolt for post-anchoring of an existing concrete structure as claimed in claim 1, characterized in that: The following steps are also included: After the variable diameter anchor bolt is implanted, install the rear steel structure and screw on the washers and nuts that come with the variable diameter anchor bolt.

4. A construction method for post-anchoring variable diameter anchor bolts in an existing concrete structure, characterized in that: The following steps are involved: According to the requirements of the design drawings, the corresponding variable diameter anchor bolts are used to lay out and locate in the existing concrete structure, and the impact drill with a variable diameter drill rod is used to drill holes to form the rebar holes; In this step, according to the basic anchoring depth l of the rebar, s Calculate the basic anchorage depth l of variable diameter rebar s’ , the calculation formula is as follows: l s’ ＝l s1 +l s2 l s1 ＝α1l s l s2 ＝α2l s Among them, l s =0.2α spt df y / f bd l s1 ——The anchoring length of the front large diameter; l s2 ——The anchoring length of the rear small diameter; α1——coefficient, ranging from 0.2 to 0.3; α2——coefficient, ranging from 0.7 to 0.8; After the hole is formed, use a hard brush or a hard nylon brush to clean the wall of the hole for planting reinforcement. Use compressed air to blow away the dust in the hole for planting reinforcement and rinse with water. The hole for planting reinforcement should be 4 to 6 mm larger than the diameter of the steel bar. Use a glue injector to inject chemical glue or chemical mortar into the rebar hole. The amount of glue injected should be 2 / 3 of the hole depth. Clean the insertion part of the variable diameter anchor bolt with a wire brush, then slowly rotate it into the anchor hole and keep it still until the glue solidifies; After the variable diameter anchor bolt is implanted, the adjustment gasket is placed, and then the rear steel structure is installed, the washers and nuts provided with the variable diameter anchor bolt are screwed on, and finally the secondary grouting is carried out.

5. The construction method of post-anchoring variable diameter anchor bolts in existing concrete structures as claimed in claim 4, characterized in that: After the position of the implanted variable diameter anchor is calibrated, a dedicated person is required to provide protection within 30 minutes.

6. A construction method for post-anchoring variable diameter anchor bolts in an existing concrete structure, characterized in that: The following steps are involved: According to the requirements of the design drawings, the surface of the existing concrete structure is roughened, the corresponding variable diameter anchor bolts are used to lay out and position the existing concrete structure, and an impact drill with a variable diameter drill rod is used to drill holes to form rebar holes; In this step, according to the basic anchoring depth l of the rebar, s Calculate the basic anchorage depth l of variable diameter rebar s’ , the calculation formula is as follows: l s’ ＝l s1 +l s2 l s1 ＝α1l s l s2 ＝α2l s Among them, l s =0.2α spt df y / f bd l s1 ——The anchoring length of the front large diameter; l s2 ——The anchoring length of the rear small diameter; α1——coefficient, ranging from 0.2 to 0.3; α2——coefficient, ranging from 0.7 to 0.8; After the hole is formed, use a hard brush or a hard nylon brush to clean the wall of the hole for planting reinforcement. Use compressed air to blow away the dust in the hole for planting reinforcement and rinse with water. The hole for planting reinforcement should be 4 to 6 mm larger than the diameter of the steel bar. Use a glue injector to inject chemical glue or chemical mortar into the rebar hole. The amount of glue injected should be 2 / 3 of the hole depth. Clean the insertion part of the variable diameter anchor bolt with a wire brush, then slowly rotate it into the anchor hole and keep it still until the glue solidifies.

7. The construction method of post-anchoring variable diameter anchor bolts in existing concrete structures as claimed in claim 6, characterized in that: After the position of the implanted variable diameter anchor is calibrated, a dedicated person is required to provide protection within 30 minutes.

8. The construction method of post-anchoring variable diameter anchor bolts in existing concrete structures as claimed in claim 6, characterized in that: The following steps are also included: After the variable diameter anchor bolts are implanted, the surface of the existing concrete structure is washed and the interface agent is brushed on it. Then the vertical steel bars, stirrups and tension bars are tied and reinforced, the formwork is supported, and finally the micro-expansion concrete is poured.

9. The construction method of post-anchoring variable diameter anchor bolts in existing concrete structures according to any one of claims 1 to 8, characterized in that: Before injecting glue, keep the rebar hole dry.

Images