Construction method for fabricated anchoring node of sunken post-tensioning anti-floating anchor

Abstract

The invention relates to the technical field of foundation engineering, in particular to a sunken post-tensioning anti-floating anchor rod fabricated anchoring joint construction method which comprises the following steps: carrying out an anchor rod uplift bearing capacity test; constructing a cushion layer and manufacturing an anchor rod, wherein the anchor rod comprises a steel strand; an anchor rod construction point is positioned on the cushion layer; drilling and cleaning an anchor hole; lowering the anchor rod; performing primary normal-pressure grouting and secondary high-pressure grouting; maintaining the anchor rod; constructing a waterproof layer; binding reinforcing steel bars and installing a sealing anchor base; pouring structural bottom plate concrete; tensioning and locking the anchor rod; according to the construction method, it can be guaranteed that the site of the structural bottom plate is flat, operation of constructors and transportation of mechanical equipment are facilitated, the effect of protecting anchoring joints of the anchor rods is achieved, and the damage risk of the anchoring joints is reduced; compared with a traditional convex type or concave type anchoring node, the bottom plate can be reduced by a certain thickness, waterproof construction operation is simpler and more convenient, the labor material cost can be greatly reduced, the construction difficulty can be lowered, the self weight of the bottom plate is reduced, and the effect of shortening the construction period is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of foundation engineering, in particular to a concave post-tensioning anti-floating anchor rod assembly type anchoring node construction method. BACKGROUND

[0002] According to the survey results, the site is basically a cut area, so most of the proposed buildings use shallow foundations, with medium weathered rock as the foundation bearing layer. Before construction, the ground around the foundation pit is closed, and a water collection well is set up inside the foundation pit for water pumping, and drainage ditches are set up around it for drainage. The anti-floating measures for anchor rod construction are implemented. For such construction scenarios, the conventional anti-floating anchor rod construction has the defects of affecting the safety of the anchoring node due to the transportation of mechanical equipment, large thickness of the foundation slab, complex and costly waterproof construction, long construction period, etc. SUMMARY

[0003] In order to solve the problems existing in the prior art, the present application provides a concave post-tensioning anti-floating anchor rod assembly type anchoring node construction method.

[0004] The concave post-tensioning anti-floating anchor rod assembly type anchoring node construction method provided by the present application adopts the following technical solution: S1, anchor rod uplift bearing capacity test; S2, cushion construction and anchor rod manufacturing, the anchor rod including a steel strand; S3, positioning the anchor rod construction point on the cushion; S4, anchor hole drilling and hole cleaning; S5, lowering the anchor rod; S6, primary normal pressure grouting and secondary high pressure grouting; S7, anchor rod maintenance; S8, waterproof layer construction; S9, steel bar binding and anchor base installation; S10, structure slab concrete pouring; S11, anchor rod tensioning and locking.

[0005] By adopting the above technical solution, the concave post-tensioning anti-floating anchor rod assembly type anchoring node construction method of the present application can ensure the flatness of the structure slab site, facilitate the operation of construction personnel and the transportation of mechanical equipment, and achieve the effect of protecting the anchor rod anchoring node, reducing the risk of damage to the anchoring node. Compared with the traditional convex or concave anchoring node at the bottom plate, a certain thickness can be reduced, and the waterproof construction operation is more simple and convenient, which not only can greatly reduce the labor and material costs, but also can reduce the construction difficulty and the self-weight of the bottom plate, achieving the effect of shortening the construction period. According to statistics, compared with the traditional convex anti-floating anchor rod, the construction method can save 34.5% of the cost and 40% of the construction period.

[0006] Preferably, the soft plastic pipe is sleeved on the outer upper part of the steel strand, the wave-shaped sleeve pipe is sleeved on the lower part, a plurality of brackets are sleeved at the interval between the outer sides of the soft plastic pipe and the wave-shaped sleeve pipe, the spiral rib is sleeved at the bottom of the wave-shaped sleeve pipe, and the extrusion anchor and the conical sleeve pipe are installed at the bottom end of the steel strand.

[0007] By adopting the technical scheme, the anchor rod system with reasonable structure and remarkable uplift resistance effect is formed.

[0008] Preferably, the cross frame is installed at the anchor hole, and the steel strand is bound with the cross frame to ensure the centering of the steel strand.

[0009] By adopting the technical scheme, the centering of the steel strand is effectively ensured.

[0010] Preferably, when the waterproof layer is constructed, the JS waterproof paint is first applied to the anti-floating anchor rod and the surrounding ground, then the self-adhesive polymer modified asphalt waterproof roll material is used for local paving of the anti-floating anchor rod, then the waterproof rubber sleeve ring is sleeved on the anchor rod, the outer side of the waterproof rubber sleeve ring is covered and paved again by using the self-adhesive polymer modified asphalt waterproof roll material, the JS waterproof paint and the oil paste are filled in the waterproof rubber sleeve ring in sequence, and the water-swelling waterstop is wound around the top of the anchor rod.

[0011] By adopting the technical scheme, the overall waterproof effect, especially the waterproof effect at the anchoring point, is significantly improved.

[0012] Preferably, the anchor sealing base comprises a pad plate, supporting legs and a steel pipe, the supporting legs are arranged at the four corners of the pad plate, the steel pipe is fixedly connected to the top surface of the pad plate, and the steel strand sleeved with the soft plastic pipe passes through the center hole of the pad plate.

[0013] By adopting the technical scheme, the height of the anchor sealing base is adjusted by the length of the supporting legs at the four corners, the pad plate disperses the tension stress of the anchor rod, reduces the local stress of the concrete at the anchor rod, the anchoring node is embedded in the top of the structure bottom plate, the damage risk of the anchoring node is reduced, the construction progress is accelerated, and the material cost and labor cost are saved.

[0014] Preferably, before the structure bottom plate concrete is poured, the plastic film is filled in the steel pipe to fix the plastic film and the steel pipe together to form the anchoring node sealing.

[0015] By adopting the technical scheme, the concrete is prevented from being poured into the steel pipe by mistake when the concrete is poured.

[0016] Preferably, the anchor rod drilling machine is used to drill the hole, the rock powder is blown out while drilling, the drilling is stopped after reaching the predetermined hole depth, and the hole is cleaned by continuing to blow air, and the perpendicularity, hole diameter and depth of the hole are checked after the hole cleaning is completed.

[0017] Preferably, in S9, the bent reinforcement is placed at the position of the anchor rod and is bound with the main reinforcement.

[0018] Preferably, in S9, the stirrup is arranged on the upper part of the structure base plate, the steel bar is laid on the upper part of the structure base plate, the collision steel bar at the position of the anchor base is adjusted and avoided, and then the steel bar on the upper part of the structure base plate is bound. BRIEF DESCRIPTION OF DRAWINGS

[0019] Fig. 1 Fig. 1 is a schematic diagram of an anchor rod structure according to an embodiment of the present application.

[0020] Fig. 2 Fig. 2 is a schematic diagram of a bracket structure according to an embodiment of the present application.

[0021] Fig. 3 Fig. 3 is a schematic diagram of an anchor head structure of an anchor rod according to an embodiment of the present application.

[0022] The following signs are explained: 1, cushion layer; 2, steel strand; 3, soft plastic pipe; 4, wave-shaped sleeve; 5, bracket; 6, spiral reinforcement; 7, extruded anchor; 8, conical sleeve; 9, cross; 10, grouting body; 11, waterproof layer; 12, waterproof rubber sleeve ring; 13, oil paste; 14, waterproof protective layer; 15, water-swelling waterstop; 16, anchor base; 161, base plate; 162, supporting leg; 163, steel pipe; 17, structure base plate; 18, bent steel bar; 19, anchorage device. DETAILED DESCRIPTION

[0023] The present application is further described below. Figs. 1-3 The present application is further described below.

[0024] An embodiment of the present application discloses a recessed post-tensioning anti-floating anchor rod assembly type anchoring node construction method, which comprises the following contents: S1, preparation work, specifically comprising: before large-area anchor rod construction, a basic test of not less than three roots should be carried out to determine the site rock layer parameters; the maximum load of the basic test should not be less than twice the characteristic value of the single anchor rod uplift bearing capacity, and preferably added to the destruction, and the load increment is preferably 10% of the maximum test load; after determining the anchor rod parameters according to the test results, the large-area construction is carried out, and the basic test anchor rod is not used for engineering anchor rod.

[0025] S2, cushion layer 1 construction and anchor rod manufacturing, specifically comprising: pouring a 100mm thick C15 plain concrete layer as a cushion layer 1 before anchor rod construction; according to the length of the anchor rod and the design requirements, the length of the steel strand 2 is determined, the soft plastic pipe 3 is sleeved on the outer side of the upper part of the steel strand 2, the wave-shaped sleeve 4 is sleeved on the lower part, and a plurality of brackets 5 are sleeved and installed at intervals on the outer sides of the soft plastic pipe 3 and the wave-shaped sleeve 4, the spiral reinforcement 6 is sleeved on the bottom of the wave-shaped sleeve 4, and the extruded anchor 7 and the conical sleeve 8 are installed at the bottom end of the steel strand 2.

[0026] S3, anchor rod positioning, specifically comprising: the anchor rod is numbered uniformly, the steel bar head is set on the cushion layer 1 according to the design drawing, and the special situation is appropriately moved after approval.

[0027] S4. Hole Formation and Cleaning: This includes drilling with a dedicated anchor drilling rig, maintaining a steady drilling position for 1-2 minutes after reaching the designed depth. The allowable deviation of the verticality of the borehole should be less than 1%, the allowable deviation of the hole position should be ±50mm, and the allowable deviation of the top surface elevation of the anchor rod should be ±10mm. Record the drilling data and collect rock powder at the beginning and end of the anchoring section. If the borehole is in a weak rock layer, all parties should be notified to extend the hole depth and continue drilling until the standard is met. Blow out the rock powder while drilling. After reaching the predetermined hole depth, stop drilling and continue to supply air to clean the hole. After cleaning the hole, perform a self-inspection of its verticality, hole diameter, and depth.

[0028] S5. Lowering the anchor rod, specifically including: inspecting the anchor rod before lowering it, and manually inserting it into the hole along the hole wall after confirming there are no problems. Install a cross 9 made of steel bars at the hole opening according to the drawings. Tie the steel strand 2 to the cross 9 to ensure that the steel strand 2 is centered and control the exposed length of the steel bars. The grouting pipe is inserted into the borehole together with the steel strand 2. The steel strand 2 should extend beyond the bottom of the pit by no less than 1.2 times the designed drilling length.

[0029] S6. Primary atmospheric pressure grouting and secondary high pressure grouting, specifically including: forming a grout body 10 inside the anchor hole; grouting using M35 pure cement mortar with added micro-expansion agent; grouting material using ordinary Portland cement, strength grade 42.5, chloride <0.1%, water-cement ratio 0.45-0.50 pure cement grout; grouting pressure 0.5-0.8MPa; the grouting pump should be test-run before use, and pipe joints should be securely connected and sealed; the grouting pipe should be inserted into the bottom of the hole and then pulled up 50mm-100mm before grouting begins, and grouting should be continuous; The grouting pipe is tied together with the steel strand 2 and placed into the borehole. The grouting pipe should be able to withstand a pressure of 1MPa at a time. During grouting, clean the area around the anchor bolt hole to ensure that no dust or stone chips fall into the anchor bolt. After filling the anchor bolt hole, use a wooden pole to vibrate the hole to confirm that the air and moisture in the hole have come out of the anchor bolt hole. After standing for 5 minutes (if shrinkage occurs after the first grouting, grout should be continuously added until there is no shrinkage in the hole), perform a second high-pressure grouting. After 12 hours, the anchor bolt hole should be grouted and cleaned.

[0030] S7. Maintenance, specifically including: the anchor bolts should not be bumped during the maintenance period. When the concrete in the hole collapses or shrinks significantly, cement mortar of the same strength should be poured into the hole opening in a timely manner.

[0031] S8. Construction of Waterproof Layer 11 includes: To prevent damage to the anchor bolts caused by nighttime earthwork excavation and machinery entering the anchor bolt construction area, the area should be marked; the machinery entering the anchor bolt construction area should have its travel route marked on site; after the anchor bolt grouting construction and curing are completed, the rod body should be coated with epoxy resin; when constructing Waterproof Layer 11, JS waterproof coating should be applied to the anti-buoyancy anchor bolt and the surrounding ground first, then self-adhesive polymer modified bitumen waterproof membrane should be used to partially cover the anti-buoyancy anchor bolt, then the waterproof rubber collar 12 should be put into the anchor bolt, and the outer part of the waterproof rubber collar 12 should be covered and laid again with self-adhesive polymer modified bitumen waterproof membrane. At the same time, JS waterproof coating and grease 13 should be filled into the waterproof rubber collar 12 in sequence, so that the anchor bolt, waterproof rubber collar 12, grease 13 and waterproof membrane form Waterproof Layer 11, completing the anchor bolt waterproofing measures. Waterproof protective layer 14 is constructed on top of Waterproof Layer 11, and a water-swellable waterstop strip 15 is wrapped around the top of the anchor bolt.

[0032] S9. Reinforcing bar binding and installation of anchor base 16, specifically including: the prefabricated anchor base 16 includes a base plate 161, legs 162 and steel pipe 163. The base plate 161 is made of 20mm thick steel plate, with the bottom of the plate 120mm from the finished surface of the structure. The legs 162 are set at the four corners of the base plate 161. The steel pipe 163 is fixed to the top surface of the base plate 161. The steel pipe 163 has an inner diameter of 250mm, a height of 100mm and a thickness of 3mm, and is arranged with steel strand 2 in the center. According to the design drawings, select the reinforcing bar type and size parameters, lay the lower reinforcing bars of the structural base plate 17 according to the marked line position, then bind them, and place concrete pads. Place 2C22 bent-up steel bars 18 at the anchor bolt location and tie them to the main reinforcement; calculate the height of the anti-buoyancy anchor bolt anchoring node according to the location of the anti-buoyancy anchor bolt hole, adjust the height of the support leg 162 to place the prefabricated sealing anchor base 16, and then pass the steel strand 2 with the soft plastic tube 3 through the four central holes of the pad plate 161. The lifting height of the sealing anchor base 16 can be manually adjusted according to the height difference between the pad layer 1 and the structural base plate 17; support the upper stirrups of the structural base plate 17, lay the upper reinforcement of the structural base plate 17, adjust the collision reinforcement at the location of the sealing anchor base 16 to avoid collision, and then tie the upper reinforcement of the structural base plate 17; before pouring the concrete of the structural base plate 17, fill the inside of the steel pipe 163 with plastic film, and wrap the plastic film and the steel pipe 163 together with tape to form an anchoring node seal to prevent the concrete from being accidentally poured in.

[0033] S10. Concrete pouring of structural base slab 17, specifically including: after completing the installation of the anchor base 16 and the internal plastic film filling operation, pouring concrete in sections of structural base slab 17; curing the concrete of structural base slab 17 until the concrete strength of structural base slab 17 reaches 25MPa and the grouting strength of the anchor body reaches 31.5MPa or above, before subsequent anchor tensioning can be carried out.

[0034] S11. Anchor bolt tensioning and locking, specifically including: using anchor 19, the locking tension value of the prestressed anchor bolt is 1.05-1.10 times the anchor bolt tension design value; before the anchor bolt is formally tensioned, it is advisable to pre-tension the anchor bolt 1-2 times with 10%-15% of the tension design value; the strength grade of the grouting body 10 should reach the design strength before tensioning; the locking tension value of the prestressed anchor bolt is 1.2 times the anchor bolt tension design value; the anchor bolt tensioning should be applied gradually, and the loading rate should not exceed 0.1 times the anchor bolt bearing capacity characteristic value per minute; the anchor bolt displacement and pressure gauge pressure under the tension value should remain stable; Before tensioning the anchor bolts, the tensioning equipment should be calibrated and standardized. Formal tensioning should be carried out in stages, with tensioning to the design load lasting for 10 minutes. Tensioning should be uniform and orderly to avoid the adverse effects of concentrated tensioning in local areas on adjacent anchor bolts. During tensioning, it is forbidden to disturb the reinforcement, jacks, or other clamps. Anchor bolt tensioning should be applied gradually, with a loading rate not exceeding 0.1 times the characteristic value of the anchor bolt bearing capacity per minute. The anchor bolt displacement and pressure gauge pressure should remain stable under the tension value. The load should be held for 10 minutes at the design load. The tension load and deformation should be fully recorded, and locking should be performed promptly after tensioning is completed.

[0035] S12. Anchor head sealing, specifically including: cutting the excessively long prestressed tendons of the anti-buoyancy anchor rod, the exposed length of the prestressed tendons after anchoring should not be less than 30mm; placing an A4@50X50 steel mesh on the upper part of the anchor head, and then filling it densely with C40 micro-expansion anti-seepage (P8) high-strength grout to complete the anchor sealing. After the compressive strength of the anchor head reaches 1.2MPa, construction can proceed.

[0036] The prefabricated anchoring joint construction method of the concave post-tensioned anti-buoyancy anchor bolt of this invention can ensure that the site of the structural base plate 17 is flat, which is convenient for construction personnel to operate and for the transportation of mechanical equipment, and can achieve the effect of protecting the anchor bolt anchoring joint and reducing the risk of damage to the anchoring joint. Compared with the traditional convex or concave anchoring joint, the base plate thickness can be reduced, and the waterproof construction operation is simpler. It can not only greatly reduce labor and material costs, but also reduce construction difficulty and reduce the self-weight of the base plate, thus shortening the construction period. According to statistics, compared with the traditional convex anti-buoyancy anchor bolt, the construction method of this invention can save 34.5% of the cost and 40% of the construction period.

[0037] The anchoring node is supported by the prefabricated anchor base 16, the height of which is adjusted by the length of the four corner legs 162. The pad 161 disperses the tension stress of the anchor rod, reduces the local stress of the concrete at the anchor rod, and the anchoring node is embedded in the top of the structural base plate 17, which reduces the risk of damage to the anchoring node, speeds up the construction progress, and saves material and labor costs.

[0038] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A construction method for a prefabricated anchoring joint of a concave post-tensioned anti-buoyancy anchor bolt, characterized in that, Includes the following: S1. Conduct an anchor pull-out bearing capacity test; S2, Subbase (1) construction and anchor bolt fabrication, the anchor bolts include steel strands (2); S3. Locate the anchor bolt construction point on the cushion layer (1); S4. Anchor hole drilling and cleaning; S5. Lower the anchor bolt; S6. Primary atmospheric pressure grouting and secondary high pressure grouting; S7. Anchor bolt maintenance; S8, Waterproofing layer (11) construction; S9. Rebar binding and installation of anchor base (16); S10, Concrete pouring of structural base slab (17); S11, Anchor bolt tensioning and locking.

2. The construction method for the assembled anchoring node of the concave post-tensioned anti-buoyancy anchor bolt according to claim 1, characterized in that: A soft plastic tube (3) is fitted on the upper part of the outer side of the steel strand (2), and a corrugated sleeve (4) is fitted on the lower part. Multiple brackets (5) are fitted and installed at intervals on the outer side of the soft plastic tube (3) and the corrugated sleeve (4). A spiral rib (6) is fitted on the bottom of the corrugated sleeve (4), and an extrusion anchor (7) and a tapered sleeve (8) are installed at the bottom end of the steel strand (2).

3. The construction method for the assembled anchoring node of the concave post-tensioned anti-buoyancy anchor bolt according to claim 2, characterized in that: Install a cross (9) at the anchor hole and tie the steel strand (2) to the cross (9) to ensure that the steel strand (2) is centered.

4. The construction method for the assembled anchoring node of the concave post-tensioned anti-buoyancy anchor bolt according to claim 3, characterized in that: When constructing the waterproof layer (11), first apply JS waterproof coating to the anti-buoyancy anchor rod and the surrounding ground, then apply self-adhesive polymer modified bitumen waterproof membrane to the anti-buoyancy anchor rod locally, then put the waterproof rubber ring (12) into the anchor rod, and then cover the outer part of the waterproof rubber ring (12) with self-adhesive polymer modified bitumen waterproof membrane again. At the same time, fill the waterproof rubber ring (12) with JS waterproof coating and grease (13) in sequence, and wrap a water-swellable waterstop strip (15) around the top of the anchor rod.

5. The construction method for the assembled anchoring node of the concave post-tensioned anti-buoyancy anchor bolt according to claim 4, characterized in that: The anchor base (16) includes a pad (161), legs (162) and steel pipe (163). The legs (162) are set at the four corners of the pad (161), and the steel pipe (163) is fixed to the top surface of the pad (161). The steel strand (2) with the soft plastic tube (3) is passed through the central hole of the pad (161).

6. The construction method for the assembled anchoring node of the concave post-tensioned anti-buoyancy anchor bolt according to claim 5, characterized in that: Before pouring concrete for the structural base slab (17), a plastic film is filled inside the steel pipe (163) to fix the plastic film and the steel pipe (163) together to form an anchoring node seal.

7. The construction method for assembled anchorage joints of concave post-tensioned anti-buoyancy anchors according to any one of claims 1-6, characterized in that: An anchor drilling rig is used to drill holes. Rock powder is blown out during drilling. After the predetermined hole depth is reached, drilling is stopped and air is supplied to clean the hole. After the hole is cleaned, its verticality, hole diameter and depth are checked.

8. The construction method for assembled anchoring joints of concave post-tensioned anti-buoyancy anchors according to any one of claims 1-6, characterized in that: In S9, a bent-up steel bar (18) is placed at the anchor position and tied to the main reinforcement.

9. The construction method for the assembled anchoring node of the concave post-tensioned anti-buoyancy anchor bolt according to any one of claims 1-6, characterized in that: In S9, stirrups are installed on the upper part of the structural base plate (17), upper steel bars are laid on the structural base plate (17), collision steel bars at the location of the anchor base (16) are adjusted to avoid collision, and then upper steel bars of the structural base plate (17) are tied.

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