CN111997101A - Prestressed anti-corrosion and anti-floating anchor rod and construction method - Google Patents

Abstract

The invention discloses a prestressed anti-corrosion and anti-floating anchor rod and a construction method. The first cylinder is integrally formed by pre-grouting casting, the part of the first water stop plate is exposed to the first cylinder body, and the second cylinder is formed by casting on the outside of the exposed part of the first water stop plate to form a prefabricated anchor rod. The exposed part of the first water stop plate is wrapped by the two cylinders, the upper part of the slow-bonding prestressed steel strand is sleeved with a second water-stop plate, and the interior of the second water stop plate and the slow-bonding prestressed steel strand are supplemented by pouring A supplementary pouring cylinder is formed, so that the supplementary pouring column and the second column are connected. Through the above method, the prestressed anti-corrosion and anti-floating anchor rod and its construction method of the present invention adopt slow-bonding prestressed steel strands, and the new waterproof structure and construction method are used to prevent the entire anchor rod from being corroded by water, and to avoid the failure of the anti-floating anchor rod. The problem.

Description

Prestressed anti-corrosion and anti-floating anchor rod and construction method

technical field

The invention relates to the field of prestressed anti-floating anchor rods, in particular to a prestressed anti-corrosion anti-floating anchor rod and a construction method.

Background technique

Anti-floating anchor is an anti-floating technology used by underground structures to resist water buoyancy. It is widely used at home and abroad, especially in China in recent years, with the construction of basements, subways, underground transportation hubs, underground spaces, The buried depth of hydraulic construction and other underground projects is getting deeper and deeper, and the anti-floating anchor is increasingly playing an irreplaceable and important role.

Anti-floating anchors are generally permanent structures, which are divided into two categories: prestressed anchors and fully bonded anchors (non-prestressed anchors). The construction process of using prestressed bolts is relatively complicated, the construction management is inconvenient, and the casing needs to be set when the anchor head passes through the underground structure. Therefore, the steel strand in the anti-floating anchor will be eroded by groundwater, gradually corroded, and the tensile bearing capacity will be reduced.

SUMMARY OF THE INVENTION

The main technical problem to be solved by the present invention is to provide a prestressed anti-corrosion and anti-floating anchor rod and a construction method thereof, adopting slow-bonding prestressed steel strands, and using a new waterproof structure and construction method to avoid the whole anchor rod being corroded by water and to avoid occurrence of The problem of anti-floating anchor failure.

In order to solve the above-mentioned technical problems, a technical solution adopted in the present invention is to provide a prestressed anti-corrosion and anti-floating anchor rod, which includes a plurality of slow-bonding prestressed steel strands, and the slow-bonding prestressed steel strands are vertically mounted. It is supported by the installation centering spacer in the vertical direction, and the lower end passes through the lower bearing plate and is connected with the extrusion anchor. The upper end of the slow bonding prestressed steel strand is bent obliquely with The lower end of the prestressed steel strand is sleeved with a first water stop plate, and the first water stop plate, the lower bearing plate and the lower end of the slow-bonded prestressed steel strand are integrally formed by pre-grouting casting to form a first cylinder , the part of the first water stop plate is exposed to the first cylinder, and the prefabricated anchor rod is formed after casting the outside of the exposed part of the first water stop plate to form a second cylinder, and the second cylinder wraps the first stop In the exposed part of the water plate, the first cylinder and the second cylinder are integrally connected by the first water stop plate. The upper part of the slow-bonding prestressed steel strand is sleeved with a second water stop plate. The supplementary pouring column is formed by supplementary pouring between the interior of the water plate and the slow-bonded prestressed steel strand.

In a preferred embodiment of the present invention, the second cylinder is directly poured outside the borehole and then the prefabricated bolt is put into the borehole, or the first cylinder is poured and the above-mentioned part is put into the borehole Then, a second cylinder is poured in the drilled hole, and the first cylinder and the second cylinder are cylindrical structures.

In a preferred embodiment of the present invention, the first water stop plate is an annular water stop plate, and its upper and lower ends have funnel-shaped openings.

In a preferred embodiment of the present invention, the centers of the lower bearing plates are evenly spaced between the slow-bonding prestressed steel strands, and the upper ends of the slow-bonding prestressed steel strands are sleeved with water Expanded water stop ring, the upper end of the slow-bonding prestressed steel strand passes through the upper bearing plate and is connected with the finished anchorage, and the lower end of the slow-bonding prestressed steel strand is installed between the lower bearing plate There is a first elasticity, a second elastic piece is installed between the upper end and the upper bearing plate, the upper end of the slow-bonded prestressed steel strand is bent, and its bending radius is 5000mm.

In order to solve the above-mentioned technical problems, another technical solution adopted by the present invention is to provide a construction method for the above-mentioned prestressed anti-corrosion and anti-floating anchor rod, which includes the following steps: a. Prefabricated bolts: at least three slow-bonded prestressed steel strands are evenly distributed along the circumference, supported and fixed by a plurality of centering spacers arranged at intervals in the vertical direction, and the lower end passes through the first water stop plate and the lower bearing plate , The first elastic member is connected with the extrusion anchor, the mold is sleeved on the outside of the lower end of the steel strand, and the upper half of the first water stop plate is exposed to the mold, and then the first cylinder is formed by grouting and casting, and removed after the casting is completed. Mold and maintenance, the first cylinder outside the anti-penetration treatment, made of prefabricated anchor; b. Drilling: Before drilling, determine the hole position according to the design requirements, make a mark, use wet drilling, and clean the hole with water after drilling until the hole flows out of clean water; c. Pouring: Put the casting conduit and the prefabricated anchor rod made in step a into the drilled hole together, and complete the grouting at one time with the grouting slurry. When the orifice overflows, the grouting can be stopped. The slurry should be grouted before the final setting. Fill in the grout in time until it is full, and determine the perfusion pressure according to the engineering conditions and design requirements to ensure the perfusion density of the slurry. Can penetrate upward; d. End treatment: excavate along the outer circumference of the prefabricated bolt to form a construction pit, break the pouring part at the upper end of the prefabricated bolt, and then put on the second water stop plate, and the inside of the second water stop plate is supplemented by pouring and molding, so that the supplementary pouring column is formed. The body and the second column are connected, and then the cushion is poured. The pouring height of the cushion must be lower than the second water stop, and the upper end of the second water stop must be exposed, and then the reinforcement is bound longitudinally and laterally on the cushion. After the steel bars are bound, install a water stop ring, an upper bearing plate, a second elastic member and an anchorage on each slow-bonded prestressed steel strand and reserve a tension groove, and then pour the bottom plate and surface layer; e. Tensioning and sealing anchors; after the concrete strength of the bottom plate reaches 100% of the design strength, the tensioning can be carried out, and the end sealing treatment is done after the prestressed tendons are tensioned.

In a preferred embodiment of the present invention, in the step a, the lower end of the slow-bonding prestressed steel strand is peeled off part of the PE jacket and extruded, and the steel strand is exposed to 1-5 mm of the extrusion anchor, and the slow-bonding steel strand is removed. For the stains on the surface of the stranded wire, install a spacer frame every 1000mm to center, and fix it with binding. After removing the mold, brush two layers of waterproofing agent for anti-penetration treatment, and grouting and pouring through C40 concrete to form the first column.

In a preferred embodiment of the present invention, before drilling in the step b, the hole position is determined according to the design requirements, and a mark is made. The positioning deviation of the anchor hole should not be greater than 20mm, and the deviation of the anchor hole should not be greater than 1%. The drilling depth beyond the anchor rod should not be less than the design length, nor greater than the design length.

In a preferred embodiment of the present invention, when the anchor rod is inserted in the step c, the prestressed tendons should be prevented from being twisted and bent, and the rod body is placed in the same angle as the drilling angle, and the C35 fine stone concrete is poured underwater. A second cylinder is formed.

In a preferred embodiment of the present invention, in the step d, the reinforcing bars on the bottom plate should actively avoid or bypass the steel strands, and after the reinforcing bars on the bottom plate are bound, install rubber water-stop rings and welding tension end pads one by one. The steel strand prevents two water-stop rings within the scope of the bottom plate, and a tension groove is reserved with a polystyrene foam board.

In a preferred embodiment of the present invention, in the end-capping treatment in step f, the excess steel strand is first cut off with a grinding wheel, and the length of the remaining exposed steel strand is not less than 30mm, and then the tensioned end and its surroundings are cleaned Clean, brush two coats of waterproofing agent, and finally seal the tension end with micro-expanded fine stone concrete and vibrate to compact it.

The beneficial effects of the present invention are as follows: the prestressed anti-corrosion and anti-floating anchor rod and its construction method of the present invention adopt slow-bonding prestressed steel strands, and the whole anchor rod is prevented from being corroded by water through the new waterproof structure and construction method, and the occurrence of anti-floating The failure of the anchor rod has a service life of more than 50 years.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, under the premise of no creative work, other drawings can also be obtained from these drawings, wherein:

Fig. 1 is the structural representation of a preferred embodiment of the prestressed anti-corrosion and anti-floating anchor rod and the construction method of the present invention;

Fig. 2 is the partial structure schematic diagram of Fig. 1;

Fig. 3 is the partial structure schematic diagram of Fig. 1;

Figure 4 is a schematic diagram of the partial structure of Figure 1 (the slow-bonded prestressed steel strand is not shown in the figure);

The symbols of the components in the accompanying drawings are as follows: 1. Slowly bonded prestressed steel strand, 2. Centering spacer, 3. Lower bearing plate, 4. Extrusion anchor, 5. First water stop plate, 6. The first cylinder, 7, the second cylinder, 8, the second water stop plate, 9, the filling cylinder, 10, the first elastic piece, 11, the second elastic piece, 12, the water stop ring, 13, the finished product Anchorage, 14, upper bearing plate, 15, cushion layer, 16, base layer, 17, surface layer.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Please refer to Fig. 1 to Fig. 4, a prestressed anti-corrosion and anti-floating anchor rod, including a plurality of slow-bonded prestressed steel strands 1, and the slow-bonded prestressed steel strands 1 are vertically separated by installation and centering The frame 2 is supported, the lower end passes through the lower bearing plate 3 and is connected with the extrusion anchor 4, the upper end of the slow-bonding prestressed steel strand 1 is bent obliquely with the vertical direction, and the slow-bonding prestressed steel strand 1 is The lower end is sleeved with a first water stop plate 5. The lower end of the first water stop plate 5, the lower bearing plate 3 and the slow-bonding prestressed steel strand 1 are integrally formed by pre-grouting casting to form a prefabricated anchor rod. The part of 5 is exposed on the first cylinder 6, the prefabricated anchor rod and the grouting pipe are put into the borehole and then grouted to form the second cylinder 7, the second cylinder 7 wraps the exposed part of the first water stop plate 5, The first water stop plate 5 connects the first cylinder 6 and the second column body 7 integrally, and the upper part of the slow-bonding prestressed steel strand 1 is sleeved with a second water stop plate 8, and the second water stop plate 8 is gentle inside. A supplementary pouring cylinder 9 is formed between the bonded prestressed steel strands 1 through supplementary casting, so that the supplementary pouring column 9 and the second column 7 are connected.

In addition, the first water stop plate 5 is an annular water stop plate, and its upper and lower ends are open in a funnel shape.

In addition, the center of the lower bearing plate 3 is evenly spaced between the slow-bonding prestressed steel strands 1, and the upper end of the slow-bonding prestressed steel strand 1 is sleeved with a water-swelling water stop ring 12 to prevent the slow bonding The upper end of the prestressed steel strand 1 passes through the upper bearing plate 14 and is connected with the finished anchor 13, and a first elastic member 10 is installed between the lower end of the slow bonding prestressed steel strand 1 and the lower bearing plate 3, A second elastic member 11 is installed between the upper end and the upper bearing plate 14 , and the upper end of the slow-bonded prestressed steel strand 1 is bent, and its bending radius is 5000 mm.

In addition, the first column body 6 and the second column body 7 are cylindrical structures.

A construction method for a prestressed anti-corrosion and anti-floating anchor rod, comprising the following steps:

a. Prefabricated bolts: 17.8mm specification slow-bonded prestressed steel strands are used, and their performance should meet the requirements of "Steel Strands for Prestressed Concrete" (GB/T5224-2014), and the standard tension of the retarding adhesive is applicable. The curing period is 180d, and the standard curing time is 540d. The slow-bonded prestressed steel strand must be tensioned within the tensioning period. Peel off part of the PE jacket from the lower end of the slow-bonded prestressed steel strand and extrude the steel strand to expose the extrusion anchor 1-5mm, remove the stains on the surface of the slow-bonded steel strand, and install a spacer every 1000mm for centering. It is fixed by binding, and the three slow-bonding prestressed steel strands are evenly distributed along the circumference, and are supported and fixed by three centering spacers arranged at intervals in the vertical direction. The first elastic member is connected with the extrusion anchor, the mold is sleeved on the outside of the lower end of the steel strand, the upper half of the first water stop plate is exposed to the mold, and then the first cylinder is formed by grouting with C40 concrete, and the pouring is completed. After removing the mold and performing maintenance, the first cylinder is brushed with two layers of waterproofing agent for anti-penetration treatment to make a prefabricated bolt for dismantling;

b. Drilling: Before drilling, set the hole position according to the design requirements and make a mark. The hole positioning deviation should not be greater than 20mm, and the anchor hole deviation should not be greater than 1%. Wet drilling is used. Until clear water flows out of the orifice, the diameter of the hole is greater than 200mm, and the depth of the drilled hole exceeding the bolt should not be less than the design length, nor greater than the design length of 500mm;

c. Pouring: Put the pouring conduit and the prefabricated anchor rod made in step a into the drilled hole. The prestressed tendons should be prevented from being twisted and bent. The angle of the rod body should be consistent with the drilling angle. The distance between the layers is not less than 100mm. The pouring conduit is filled with cement-based grouting material or M40 cement composite mortar. When the orifice overflows, the grouting can be stopped. The grout should be replenished in time before the final setting until it is full. The perfusion pressure should be determined according to the engineering conditions and design requirements to ensure the density of the grout. The 30 bolts should not be less than one group, and each group should have no less than 6 test blocks. The strength of the test blocks meets the design requirements, and the strength is not less than 30Mpa. After grouting, the second column and the first column pass the first stop. The water ring is integrally connected, so that the water can only penetrate upwards;

d. End treatment: excavate along the outer circumference of the prefabricated bolt to form a construction pit, break the pouring part at the upper end of the prefabricated bolt, and then put on the second water stop plate, and the inside of the second water stop plate is supplemented by pouring and molding, so that the supplementary pouring column is formed. The body and the second cylinder are connected, and then the cushion layer is poured. The pouring height of the cushion layer must be lower than the second water stop plate, at least 1/3 of the second water stop plate is exposed, and then the cushion layer is bound longitudinally and laterally. Reinforcing bars, install water stop rings, upper bearing plates, second elastic parts and anchors on each slow-bonded prestressed steel strand after the reinforcing bars are bound, and reserve tension grooves with polystyrene foam boards, and then pour the bottom plate and surface layer;

e. Tensioning and sealing anchors; tensioning can be carried out after the concrete strength of the bottom plate reaches 100% of the design strength, the characteristic value of the pull-out bearing capacity Nka is 400KN, and the tensile force F1 of the test pile and anchor is measured by 2 times the pull-out bearing capacity characteristics The value of 800KN is controlled; the locking tension F2 of the construction anchor is controlled by 650KN, and the stress control should be used as the main method and the strain check method should be used for tensioning. Within the range of +6%, the on-site prestressing records should be made during construction. The tensioning should be uniform and orderly to avoid the adverse effects of concentrated tensioning in local areas on the adjacent anchor rods. It is forbidden to disturb the tendons, jacks or other anchor fixtures during the tensioning process. After the prestressed tendons are tensioned, the end capping treatment is done. First, the excess steel strands are cut off with a grinding wheel, and the length of the remaining exposed steel strands is not less than 30mm. Then, clean the tensioned end and its surroundings, and apply two coats of waterproofing. Finally, the pit wall is painted with cement-based permeable crystalline waterproof material, and then the tension end is sealed with micro-expanded fine stone concrete and vibrated for compaction. After the construction of the prestressed anti-corrosion and anti-floating anchor rod is completed, as shown in Figure 2, since the first water stop plate connects the first column and the second column together, the bottom water will not enter the slow-bonded prestressed steel strand laterally. It flows in the vertical direction, and will not cause corrosion to the slow-bonding prestressed steel strand, as shown in Figure 3. Similarly, the upper layer water also flows in the vertical direction, and will not cause corrosion to the slow-bonding prestressed steel strand. Steel strands cause corrosion.

Example 2, in step c, the second cylinder is continuously poured on the first cylinder that has been poured in step a outside the borehole, and the second cylinder and the first cylinder are integrally connected by a first water stop ring, Then insert the above-mentioned part into the drilled hole again, and proceed to step d after supplementary pouring. The rest are the same as in Example 1.

Different from the prior art, the prestressed anti-corrosion and anti-floating anchor rod and its construction method of the present invention adopt slow-bonding prestressed steel strands, and the whole anchor rod is prevented from being corroded by water through a new waterproof structure and construction method, and the occurrence of anti-floating anchors is avoided. The problem of rod failure, the service life is more than 50 years.

The above descriptions are only the embodiments of the present invention, and are not intended to limit the scope of the patent of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the description of the present invention, or directly or indirectly applied in other related technical fields, are all applicable. Similarly, it is included in the scope of patent protection of the present invention.

Claims (10)

1. a prestressed anti-corrosion and anti-floating anchor rod is characterized in that, comprises a plurality of slow-bonding prestressed steel strands, and the slow-bonding prestressed steel strands are supported by installation centering spacers in the vertical direction , the lower end passes through the lower bearing plate and is connected with the extrusion anchor, the upper end of the slow-bonding prestressed steel strand is bent obliquely with the vertical direction, and the lower end of the slow-bonding prestressed steel strand is sleeved There is a first water stop plate, and the lower end of the first water stop plate, the lower bearing plate and the slow-bonding prestressed steel strand are integrally formed by pre-grouting casting to form a first cylinder, and the part of the first water stop plate is formed. It is exposed on the first cylinder, and the prefabricated anchor rod is formed by pouring on the outside of the exposed part of the first water stop to form a second cylinder. The second cylinder wraps the exposed part of the first water stop and passes through the first water stop. The plate makes the first cylinder and the second cylinder integrally connected, the upper part of the slow-bonding prestressed steel strand is sleeved with a second water stop plate, and the second water stop plate is inside the slow-bonding prestressed steel strand. The supplementary pouring column is formed between the lines by supplementary pouring. 2. The prestressed anti-corrosion and anti-floating anchor rod according to claim 1, characterized in that, after the second cylinder is directly poured outside the borehole, the prefabricated anchor rod is put into the borehole, or the first column After the body casting is completed, the above-mentioned parts are put into the drilled hole, and then the second cylinder is poured in the drilled hole, and the first and second cylinders are cylindrical structures. 3 . The prestressed anti-corrosion and anti-floating anchor rod according to claim 1 , wherein the first water stop plate is an annular water stop plate, and its upper and lower ends are open in a funnel shape. 4 . 4. The prestressed anti-corrosion and anti-floating anchor rod according to claim 1, characterized in that, the center intervals of the lower bearing plates between the slow-bonding prestressed steel strands are evenly arranged, and the slow-bonding prestressed The upper end of the stress steel strand is sleeved with a water-swelling water stop ring, the upper end of the slow bonding prestressed steel strand passes through the upper bearing plate and is connected with the finished anchorage, and the slow bonding prestressed steel A first elastic piece is installed between the lower end of the strand and the lower pressure-bearing plate, and a second elastic piece is installed between the upper end and the upper pressure-bearing plate. The upper end of the slow-bonded prestressed steel strand is bent, and its bending curvature The radius is 5000mm. 5. a construction method of prestressed anti-corrosion anti-floating anchor rod as claimed in claim 1, is characterized in that, comprises the following steps: a. Prefabricated bolts: at least three slow-bonded prestressed steel strands are evenly distributed along the circumference, supported and fixed by a plurality of centering spacers arranged at intervals in the vertical direction, and the lower end passes through the first water stop plate and the lower bearing plate , The first water stop plate is connected with the extrusion anchor, the mold is sleeved on the outside of the lower end of the steel strand, the upper part of the first water stop plate is exposed to the mold, and then the first cylinder is formed by grouting and pouring. The mold is removed and maintained, and the outside of the first cylinder is treated with anti-penetration; b. Drilling: Before drilling, set the hole position according to the design requirements, make a mark, use wet drilling, and clean the hole with water after drilling until the hole flows out of clean water; c. Pouring: Put the pouring conduit and the anchor rod made in step a into the drilled hole, and complete the one-time grouting with grouting. When the orifice overflows, the grouting can be stopped. The slurry should be carried out before the final setting. Fill the grout in time until it is full. Determine the perfusion pressure according to the engineering conditions and design requirements to ensure the perfusion density of the slurry. After grouting, the second cylinder and the first cylinder are integrally connected through the first water stop ring, so that the penetrate upward; d. End treatment: excavate along the outer circumference of the prefabricated bolt to form a construction pit, break the pouring part at the upper end of the prefabricated bolt, and then put on the second water stop plate, and the inside of the second water stop plate is supplemented by pouring and molding, so that the supplementary pouring column is formed. The body and the second column are connected, and then the cushion is poured. The pouring height of the cushion must be lower than the second water stop, and the upper end of the second water stop must be exposed, and then the reinforcement is bound longitudinally and laterally on the cushion. After the steel bar is bound, install the water stop ring, the upper bearing plate, the second elastic member and the anchor on each slow-bonded prestressed steel strand, and reserve the tension groove, and then pour the bottom plate and surface layer; e. Tensioning and sealing anchors; after the concrete strength of the bottom plate reaches 100% of the design strength, the tensioning can be carried out, and the end sealing treatment is done after the prestressed tendons are tensioned. 6 . The construction method according to claim 5 , wherein in the step a, the PE jacket is peeled off from the lower end of the slow-bonding prestressed steel strand for extrusion, and the steel strand is exposed to the extrusion anchor by 1-5 mm, , remove the stains on the surface of the slow-bonded steel strand, install a spacer frame every 1000mm to center, fix it with binding, remove the mold and brush two water repellants for anti-penetration treatment, and use C40 concrete for grouting to form the first cylinder. . 7. The construction method according to claim 5, characterized in that, before drilling in the step b, the hole positions are determined according to the design requirements, and marks are made, the anchor hole positioning deviation should not be greater than 20mm, and the anchor hole skewness It should not be greater than 1%, and the drilling depth exceeding the bolt should not be less than the design length, nor greater than the design length. 8. The construction method according to claim 5, characterized in that, in the step c, the pouring of the second cylinder is continued on the first cylinder that has been poured in the step a outside the borehole, and the second cylinder is It is integrally connected with the first cylinder through the first water stop ring, and then the above part is inserted into the drilled hole again, and the step d is continued after supplementary pouring. 9. construction method according to claim 5, is characterized in that, in the described step d, the reinforcement of the bottom plate should actively avoid or bypass the steel strand, and after the binding of the reinforcement of the bottom plate is completed, install the rubber water stop ring and the welding tension one by one. End pad, each steel strand prevents two water-stop rings within the scope of the bottom plate, and uses polystyrene foam board to reserve tension grooves. 10. The construction method according to claim 5, characterized in that, in the end-capping treatment in the step f, the excess steel strands are first cut off with a grinding wheel piece, and the length of the remaining exposed steel strands is not less than 30mm, and then the The pulling end and its surroundings are cleaned up, and two coats of waterproofing agent are applied. Finally, the wall of the pit is painted with cement-based permeable crystalline waterproof material, and then the tension end is sealed with micro-expanded fine stone concrete and vibrated and compacted.

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