Anti-overturning reinforcing method for miniature steel pipe anchor bar piles and vase piers

Abstract

The invention discloses an anti-overturning reinforcing method for a miniature steel pipe anchor bar pile and a vase pier. The anti-overturning reinforcing method comprises the following steps that S1, an original single-support single-column pier is transformed into a three-support thin-wall vase pier; s2, holes are drilled in the soft soil foundation, miniature steel pipes are inserted, and grouting materials are poured into the miniature steel pipes; s3, the micro steel pipe piles are rigidly connected with an original foundation through pre-embedded anchor bars and a cast-in-place bearing platform; and S4, the miniature steel pipe pile groups are arranged in a rectangular shape. Therefore, the three-support vase pier and the micro piles work together to enhance the overall stability, the micro piles improve the stress distribution of the soft soil foundation and reduce differential settlement, the equipment is light, the process is flexible, and the three-support vase pier is suitable for complex geology and space limited scenes.

Description

Technical Field

[0001] The invention relates to the field of civil engineering, and in particular to an anti-overturning reinforcement method for a micro steel pipe anchor pile and a vase pier. Background Art

[0002] In urban bridge reconstruction projects, single-column pier structures often need to be transformed into multi-support pier structures due to landscape requirements and insufficient anti-overturning capacity. For example, piers 8 and 9 of a bridge need to be changed from single-support single-column piers to three-support thin-walled vase piers to enhance stability. However, the original pier column foundation is a single pile structure, and the geological conditions are soft soil foundations, resulting in traditional reinforcement methods facing the problems of open excavation to expand the foundation, requiring an excavation depth of 9 meters to meet the foundation bearing capacity requirements, a long construction period and a great impact on the surrounding environment. On the other hand, conventional pile foundations are limited by the clearance height under the bridge, large drilling equipment cannot enter the site, and the construction feasibility is low.

[0003] In the existing technology, the above-mentioned method has defects such as low construction efficiency, high cost, and difficulty in settlement control in soft soil foundations and narrow space scenarios. There is an urgent need for a reinforcement solution with strong adaptability, flexible process and the ability to effectively improve anti-overturning capacity. Summary of the invention

[0004] The present invention aims to solve the technical problems in the above-mentioned technology at least to some extent.

[0005] To this end, the present invention discloses a method for anti-overturning reinforcement of a micro steel pipe anchor pile and a vase pier, comprising the following steps:

[0006] S1. Transform the original single-support single-column pier into a three-support thin-walled vase pier;

[0007] S2, drilling a hole in the soft soil foundation and inserting a micro steel pipe, and pouring grouting material into the micro steel pipe;

[0008] S3, rigidly connecting the micro steel pipe pile to the original foundation through pre-buried anchor bars and cast-in-place caps;

[0009] S4. Micro steel pipe pile groups are arranged in a rectangular shape.

[0010] According to the anti-overturning reinforcement method of micro steel pipe anchor piles and vase piers disclosed in the present invention, the three-support vase piers and micro piles work together to enhance the overall stability. The micro piles improve the force distribution of the soft soil foundation and reduce differential settlement. The equipment is light and the process is flexible, which is suitable for complex geological and space-constrained scenes.

[0011] In addition, the anti-overturning reinforcement method of the micro steel pipe anchor pile and the vase pier disclosed in the present invention may also have the following additional technical features:

[0012] In one embodiment of the present invention, the thickness of the micro steel pipe entering the soft soil layer ranges from 6 to 12 meters, and the pile spacing is 1.5 to 2.5 times the pile diameter.

[0013] In one embodiment of the present invention, the grouting material injection pressure is greater than or equal to 1.5 MPa, and the anchor bar tensile strength is greater than or equal to 400 MPa.

[0014] In one embodiment of the present invention, the verticality deviation of the micro steel pipe pile is less than or equal to 1 degree.

[0015] In one embodiment of the present invention, the anchor bar is connected to the original foundation by welding or bolt anchoring.

[0016] In one embodiment of the present invention, the supports of the three-support thin-wall vase pier are distributed in a triangular shape.

[0017] In one embodiment of the present invention, the 28-day compressive strength of the grouting material of the micro steel pipe pile is greater than or equal to 40 MPa.

[0018] In one embodiment of the present invention, the depth of the drilling hole penetrating the soft soil layer and entering the bearing layer is greater than or equal to 1 meter.

[0019] Additional contents and advantages of the present invention will be given in the following description or may be understood through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The technical solutions and beneficial effects of the present invention will become apparent and easily understood from the following contents in conjunction with the accompanying drawings, wherein:

[0021] Figure 1 It is a structural schematic diagram of the anti-overturning reinforcement method of the present invention. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0023] The anti-overturning reinforcement method of the micro steel pipe anchor pile and the vase pier disclosed in the present invention will be described below with reference to the accompanying drawings.

[0024] like Figure 1 As shown, a method for anti-overturning reinforcement of a micro steel pipe anchor pile and a vase pier comprises the following steps:

[0025] S1. Transform the original single-support single-column pier into a three-support thin-walled vase pier;

[0026] S2, drilling a hole in the soft soil foundation and inserting a micro steel pipe, and pouring grouting material into the micro steel pipe;

[0027] S3, rigidly connect the micro steel pipe pile to the original foundation through pre-buried anchor bars and cast-in-place caps;

[0028] S4. Micro steel pipe pile groups are arranged in a rectangular shape.

[0029] The thickness of the micro steel pipe entering the soft soil layer ranges from 6 to 12 meters, and the pile spacing is 1.5 to 2.5 times the pile diameter.

[0030] The grouting material injection pressure is greater than or equal to 1.5 MPa, and the anchor bar tensile strength is greater than or equal to 400 MPa.

[0031] The verticality deviation of micro steel pipe piles is less than or equal to 1 degree.

[0032] The connection method between the anchor bar and the original foundation is welding or bolt anchoring.

[0033] The supports of the three-pedestal thin-walled vase pedestal are distributed in a triangular shape.

[0034] The 28-day compressive strength of the grouting material of the micro steel pipe pile is greater than or equal to 40 MPa.

[0035] The drilling depth penetrates the soft soil layer and enters the bearing layer greater than or equal to 1 meter.

[0036] Specifically, for the transformation of the original single-support single-column pier into a three-support thin-walled vase pier, the top of the original single-support single-column pier is horizontally cut off using a cutting process, retaining the original pier column main structure;

[0037] High-strength chemical anchors are implanted on the cut surface. The anchor spacing is arranged in an equilateral triangle with a side length of 1.2 to 1.5 meters. The implantation depth is greater than or equal to 30d, where d is the diameter of the anchor;

[0038] The formwork is supported and poured with C50 slightly expansive concrete to form three independent bearing caps with a size of 800×800×600 mm. The top surface is provided with embedded steel plates with a thickness of 20 mm, which are connected to the bridge bearings.

[0039] In addition, glass fiber reinforced composite materials can also be used to wrap the interface between new and old concrete to enhance the interface bonding strength;

[0040] For drilling holes in soft soil foundation and inserting micro steel pipes, the interior of the micro steel pipes is filled with grouting material. A walking auger is used for drilling, the hole diameter is Φ150 mm, and the verticality control adopts a laser guidance system, with a deviation of less than or equal to 1 degree;

[0041] The drilling depth must penetrate all soft soil layers, generally 6 to 12 meters, and enter the medium weathered rock layer to a depth of more than or equal to 1 meter;

[0042] A Φ108×6mm seamless steel pipe is selected as the micropile body, and four Φ8mm overflow holes are set every 1 meter on the pipe body, and a one-way valve is set at the hole mouth;

[0043] The cement-based grouting material is injected by high-pressure grouting method, with an initial pressure of 1.5 MPa and a final pressure of 2.5 MPa. The grouting volume is calculated according to the formula Q = πr2h × 1.2, where r is the diffusion radius of 0.5 m and h is the pile length;

[0044] After grouting is completed, insert the steel cage immediately, with main reinforcement 4Φ16, stirrup Φ8@200, and the bottom of the steel cage 100 mm from the bottom of the hole;

[0045] For the rigid connection between the micro steel pipe pile and the original foundation through the pre-buried anchor bar, drill holes on the top surface of the original foundation and embed the Φ25 pre-buried anchor bar, the embedding depth is greater than or equal to 40d, and Class A glue is used for anchoring;

[0046] The connection between the anchor bar and the micro steel pipe pile is double-sided welding, with a weld length of 5d or more and a weld thickness of 8mm or more;

[0047] After welding, apply two coats of epoxy resin anti-corrosion coating, with a dry film thickness of 200μm or more;

[0048] Set up L-shaped shear keys with dimensions of 200×200×15 mm to enhance the shear resistance of the interface and arrange them evenly at intervals of 1.5 meters;

[0049] For micro steel pipe piles, the micro piles are arranged in a rectangular array, with a longitudinal spacing of 2.0 meters and a transverse spacing of 1.8 meters, both of which are 1.7 times the pile diameter;

[0050] A reinforced concrete cap beam is set on the top of the pile, with a size of 800×600 mm. The cap beam is reinforced with 6Φ22 main bars on the top and bottom, and stirrups Φ10@150;

[0051] The pedestal beam and the three-support pedestals are connected by pre-embedded steel bars, Φ20@500, to form a space frame structure.

[0052] In summary, according to the anti-overturning reinforcement method of micro steel pipe anchor piles and vase piers disclosed in the present invention, the three-support vase piers and micro piles work together to enhance the overall stability, the micro piles improve the force distribution of the soft soil foundation and reduce differential settlement, the equipment is light and the process is flexible, and it is suitable for complex geological and space-constrained scenes.

[0053] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for anti-overturning reinforcement of micro steel pipe anchor piles and vase piers, characterized in that: The following steps are involved: S1. Transform the original single-support single-column pier into a three-support thin-walled vase pier; S2, drilling a hole in the soft soil foundation and inserting a micro steel pipe, and pouring grouting material into the micro steel pipe; S3, rigidly connecting the micro steel pipe pile to the original foundation through pre-buried anchor bars and cast-in-place caps; S4. Micro steel pipe pile groups are arranged in a rectangular shape.

2. The method for anti-overturning reinforcement of micro steel pipe anchor piles and vase piers as claimed in claim 1, characterized in that: The thickness of the micro steel pipe entering the soft soil layer ranges from 6 to 12 meters, and the pile spacing is 1.5 to 2.5 times the pile diameter.

3. The method for anti-overturning reinforcement of micro steel pipe anchor piles and vase piers as claimed in claim 1, characterized in that: The grouting material injection pressure is greater than or equal to 1.5 MPa, and the anchor bar tensile strength is greater than or equal to 400 MPa.

4. The method for anti-overturning reinforcement of micro steel pipe anchor piles and vase piers as claimed in claim 1, characterized in that: The verticality deviation of the micro steel pipe pile is less than or equal to 1 degree.

5. The method for anti-overturning reinforcement of micro steel pipe anchor piles and vase piers as claimed in claim 1, characterized in that: The anchor bar is connected to the original foundation by welding or bolt anchoring.

6. The method for anti-overturning reinforcement of micro steel pipe anchor piles and vase piers as claimed in claim 1, characterized in that: The supports of the three-support thin-wall vase pier are distributed in a triangular shape.

7. The method for anti-overturning reinforcement of micro steel pipe anchor piles and vase piers as claimed in claim 1, characterized in that: The 28-day compressive strength of the grouting material of the micro steel pipe pile is greater than or equal to 40 MPa.

8. The method for anti-overturning reinforcement of micro steel pipe anchor piles and vase piers as claimed in claim 1, characterized in that: The drilling depth penetrates the soft soil layer and enters the bearing layer greater than or equal to 1 meter.

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