WO2021248822A1 - 一种扩大头预应力混凝土锚杆施工工法 - Google Patents

一种扩大头预应力混凝土锚杆施工工法 Download PDF

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Publication number
WO2021248822A1
WO2021248822A1 PCT/CN2020/129280 CN2020129280W WO2021248822A1 WO 2021248822 A1 WO2021248822 A1 WO 2021248822A1 CN 2020129280 W CN2020129280 W CN 2020129280W WO 2021248822 A1 WO2021248822 A1 WO 2021248822A1
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Prior art keywords
anchor rod
concrete
anchor
head
prestressed
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PCT/CN2020/129280
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English (en)
French (fr)
Inventor
王林
陶刚
王军
刘松梅
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江苏景源万河环境科技有限公司
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Publication of WO2021248822A1 publication Critical patent/WO2021248822A1/zh

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    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
    • E02D5/74—Means for anchoring structural elements or bulkheads
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D31/00—Protective arrangements for foundations or foundation structures; Ground foundation measures for protecting the soil or the subsoil water, e.g. preventing or counteracting oil pollution
    • E02D31/10—Protective arrangements for foundations or foundation structures; Ground foundation measures for protecting the soil or the subsoil water, e.g. preventing or counteracting oil pollution against soil pressure or hydraulic pressure
    • E02D31/12—Protective arrangements for foundations or foundation structures; Ground foundation measures for protecting the soil or the subsoil water, e.g. preventing or counteracting oil pollution against soil pressure or hydraulic pressure against upward hydraulic pressure

Definitions

  • This application relates to a fixed diameter or enlarged head prestressed concrete anchor rod and a construction method. It is an anchor rod application device that overcomes the elastic deformation of the free section of the anti-floating fixed diameter or enlarged head anchor rod body, and also relates to a variable diameter steel cage expansion head Stress concrete anchor pile and construction method (post-tensioning method).
  • the applicant’s CN2020103929335 is a post-tensioning prestressing device for an anchor rod, which includes a force applying machine 10, a support or/and a support plate, a steel bar holder, and the upper end of the support or the support plate is provided with an upper steel bar ( The hole through which the main reinforcement passes; the lower end of the anchor rod is fixed in the borehole of the anchor rod stratum or rock formation.
  • the upper reinforcement is fixed to the support plate by means of lock nuts or welding, and then concrete is poured around the reinforcement (main reinforcement) in the drilled hole .
  • Reinforcing bars (main bars) especially use fine-rolled rebar.
  • the anchor rod is provided with a support 7 on the surface of the stratum or rock drilled hole as an anchor rod, and the upper end steel bar behind the hole is held by a steel bar holder.
  • the bracket is provided with supporting legs, and the anchor nut is screwed to the finish-rolled threaded steel under the bracket hole.
  • the anchored locking bracket is placed on the surface of the stratum or rock drilled hole, and a backing plate and a pre-stressed locking nut are placed above the locking bracket; and the anchoring structure at the uppermost end of the anchor rod is poured together with the building floor. But it does not involve the construction method of enlarged head or fixed diameter or prestressed concrete anchor rod (pile).
  • the strength of sand-gravel cement three-in-one concrete is many times higher than that of mortar.
  • the strength of concrete marked c30 can reach more than 30MPa; the cost is not high, as long as ordinary cement is used.
  • CN 107044122 is a construction method proposed by the inventor to overcome the deformation of the anti-floating fixed diameter or enlarged head anchor rod system (elastic deformation of the free section of the rod and the soil creep deformation of the fixed diameter or enlarged head anchor section). Method to apply prestress, so as to achieve the purpose of controlling the deformation of pressure-bearing fixed diameter or expanding head bolt engineering practice. Based on the analysis of the deformation of these two parts, a new construction method for solving the deformation of the straight or enlarged head bolt is proposed.
  • Pressure-bearing fixed diameter or enlarged head anchor rod prestress construction method drilled to the design depth, can carry out rotary jet construction or mechanical reaming construction, lower the anchor rod and fixed diameter anchor head or expansion head (variable diameter steel bar) Cage or various capsule expansion heads, and various expansion heads, etc.), after the expansion head is in place, the expansion mechanism expands the expansion head to the design size.
  • the method proposed by the applicant in advance to solve the problem of anti-floating anchor rod basically solves the deformation problem.
  • Engineering practice shows that the displacement of the pressure-bearing fixed diameter or enlarged head anchor rod is determined by the elastic deformation of the rod body and the slip (plastic deformation) of the expanded section. Partial composition.
  • the plastic deformation and residual deformation of the expansion section of the anchor rod are related to the end pressure endured by the expansion section and the nature of the soil layer where it is located, and has nothing to do with the number of steel bars used in the rod.
  • the elastic deformation of the free section of the anchor rod is controlled.
  • the elastic deformation of the rod that is, the elastic deformation of the steel bar, is mainly controlled by the cross-sectional area of the steel bar, the elastic modulus of the steel bar, and the length of the rod.
  • the purpose of this application is to provide an anchor rod (pile) formed by pouring and solidifying an anchor rod skeleton system and prestressed concrete, and propose an anchor rod (pile) formed by pouring and solidifying an anchor rod skeleton system and prestressed concrete.
  • Tensile prestress application device through a concise and effective device, can apply prestress during on-site construction (compared to precast prestressed anchor rods, this application uses prestressed concrete to infuse the solidified anchor skeleton system, and uses post-tensioned prestressed It can be applied to eliminate the deformation of the anchor rod, which can reduce the displacement of the engineering anchor rod, the anchor rod body strain, and increase the safety and stability of the anchor rod.
  • the technical solution of the present application is an anchor rod (pile) formed by pouring and solidifying an anchor rod skeleton system and prestressed concrete, and using an application device to apply prestress by a post-tensioning method.
  • the construction and implementation steps are: drilling and positioning; Drill to the design depth, carry out rotary jetting or mechanical reaming construction and make holes, lower the anchor rods, namely the main reinforcement and enlarged head skeleton or fixed-diameter anchor head skeleton; the anchor rods are the main reinforcement and enlarged head (variable diameter steel cage Or various capsule expansion heads, and various expansion heads, etc.).
  • the expansion mechanism expands the expansion head to the design size, and then pours concrete into the expansion head, namely the expansion section and the non-expansion section.
  • the tie rod in the anchor rod that is, the main reinforcement
  • the tie rod in the anchor rod uses a device and method that can apply prestress to the main reinforcement (such as unbonded prestressed finish-rolled rebar with casing, ordinary third-level rebar, steel strand, etc.) Apply pre-stress (no bonding is convenient for later application of stress; apply the pre-stress required by design and specifications, and lock it after completion (such as nut locking, welding, etc.), and then cancel the pre-stress application equipment that needs to be removed;
  • the anchor rod The whole part is composed of poured concrete and anchor rod skeleton body; after the whole of the anchor rod reaches the rated strength, according to the requirements of engineering design and specifications, the anchoring structure set at the top of the anchor rod main reinforcement is poured together with the building bottom plate to form Anti-floating
  • it can also be poured with the building floor without applying prestress.
  • it can also be poured together with the floor of the building without prestressing.
  • Pre-stressed anti-floating and tensile anchor steel bars including main reinforcing steel (including main reinforcing steel or main reinforcing steel connection structure with main reinforcing steel through connecting nuts) as the basic bearing structure, the main reinforcing steel is finished rolled unbonded steel, and the surface of the main reinforcing steel It is equipped with an anti-corrosion grease layer, and a plastic film sleeve is arranged outside the anti-corrosion grease layer; the anti-corrosion grease layer is coated by the anti-corrosion grease layer device, and the anti-corrosion grease layer is coated without adhesive ribs.
  • the polyethylene or polypropylene plastic film is coated by a plastic extruder. The plastic casing is then molded by cooling drum.
  • the casing can be made of various materials such as metal, PP, PE, PVC, and plastic; the plastic casing is wrapped with concrete or cement mortar, cement slurry or other curable materials. And condense and solidify; after prestress is applied to the main reinforcement (prestress is applied after the fixing is completed) to form a prestressed anchor rod; the main reinforcement is locked with a nut, and the tensile steel is prestressed to form a prestressed anchor rod
  • the prestressed anchor rod can be cast on the construction site or prefabricated in the factory.
  • the main reinforcement of the anchor rod, the number of steel bars in the post-tensioned anchor rod assembly is one or more, but generally no more than 15 (otherwise it becomes a concrete pile), the specifications, performance, strength, and diameter of the reinforcement It can be determined according to the design requirements; the length, cross-sectional shape and area of the prestressed anchor rod assembly are set according to the engineering technical requirements; when the length of the rod is required for the project to be too long, the method of nut connector or other can be adopted Way, two or more steel bars are connected to achieve the required length; the steel nut connector can also be embedded in the anchor rod in advance, and the steel bars can be round steel, steel pipe, steel strand and other steel , The two ends of the section steel can also be provided with silk patterns.
  • Anchor rod components and variable diameter steel cages include but are not limited to: cube, polyhedron, regular polyhedron, tetrahedron, cuboid, cylinder, truncated cone, prism, pyramid, cone, pyramid, bamboo joint, string, Convex and concave;
  • the shape of the plane cross-section includes but is not limited to: square, rectangle, triangle, quadrilateral, rhombus, trapezoid, polygon, circle, ellipse, ring, sector, arc;
  • the anchor rod component can be solid or it can be Hollow section.
  • the prefabricated pre-stressed unbonded steel bars for anti-floating and tensile anchor rods and the materials that can be used for the elongated main bars and reinforcements, including but not limited to steel, steel strands, glass fiber, resin, glass fiber reinforced resin, aromatic Fiber, carbon fiber, graphene, carbon-related materials and their composite materials, macromolecules, macromolecular polymer materials, nanomaterials, metallic materials and non-metallic materials.
  • the top surface of the non-expanded head section of the anchor bolt can also be used as the fulcrum for applying prestress. After the concrete strength reaches the strength that can be applied to the prestress not lower than the design and specification requirements, the grouting is removed and leveled to the top surface of the anchor pile for construction The elevation of the surface is pre-stressed and tensioned and locked according to the design requirements. It can also be set according to engineering design needs.
  • the inner diameter of the pouring concrete pouring pipe is generally 4-10cm (also can be set according to the engineering design needs and the size of the hole diameter), for pouring or high-pressure pouring, mixing sand, fine stone, cement and water to meet the engineering design specifications Prestressed fine stone concrete.
  • the strength of the main body of the anchor rod is obviously increased.
  • the expansion head can be poured first, especially the expansion head with variable diameter steel cage, and also poured with concrete.
  • the strength of the expansion head is sufficient to meet the requirements of prestressing. Tension fixed end.
  • Applying a protective device to the prestressed nut means that the spiral stirrup is sleeved on the prestressed nut, and the spiral stirrup and the foundation slab reinforcement on the base are bound to avoid collision with the prestressed steel during the lashing process;
  • the foundation concrete foundation slab is poured by the formwork, which is poured together with the building slab to form a floating, tensile or compressive system.
  • the concrete is poured through a thin tube (generally no more than 150 mm in outer diameter), and the diameter of the free section of the anchor rod is controlled to be 180-300 mm, which can also be used as a rigid micro-pile;
  • This application adopts prestressed anti-floating and tensile anchor rods, including main reinforcing steel bars (including main reinforcing steel bars or main reinforcing steel bars connected by connecting nuts) as the basic load-bearing structure, especially the main reinforcing steel bars are precision-rolled unbonded steel bars ,
  • the surface of the main steel bar is provided with an anti-corrosion grease layer, and the anti-corrosion grease layer is equipped with a plastic film sleeve; the anti-corrosion grease layer is coated by the anti-corrosion grease layer device, and the anti-corrosion grease layer is coated without bonding ribs and the plastic extruder is coated with polyethylene or poly Acrylic plastic film, and then cool the barrel mold to form a plastic sleeve (pipe); outside the plastic sleeve, the method of this application includes concrete or (cement mortar, cement slurry or other curable materials) and condenses and solidifies; the prestress is applied to the main reinforcement steel bar (After pre-stress is applied, the concrete
  • the anchor body After the free section of the anchor rod, that is, the anchor body reaches the strength required by the design, it becomes the anchor rod that is pre-stressed by the post-tensioning method. Place the anchor pad on the top of the anchor rod, that is, the top of the rigid micro-pile. After the anchor pad is placed, the anchor rod reinforcement The top end is mechanically connected with the backing plate and the prestressed tendons through nuts.
  • the post-tensioning prestressing device of the anchor rod includes a force applying machine, a bracket or/and a bracket plate, a steel bar holder or a lock nut, and a hole through which the upper end of the anchor rod can pass through is provided in the center of the bracket or the bracket plate; The lower end of the steel bar is fixed in the borehole of the anchor stratum or rock formation. After the hole passes through, the upper steel bar is clamped by the steel bar clamp or locked by the nut, and the stress is applied by the force application machine. The upper steel bar is locked by the nut or welded, etc.
  • the post-tensioning pre-stressing device of the anchor rod is fixed on the support plate.
  • the anchor rod is provided with a post-tensioning pre-stressed locking bracket of the anchor rod on the surface of the stratum or rock formation.
  • the locking bracket can be prefabricated or
  • the shapes produced on site include but are not limited to cuboid, cube, cylinder, polyhedral concrete or steel parts with or without supporting feet.
  • the pre-stress locking bracket is provided with supporting feet, the main reinforcement of the anchor rod is threaded through the hole of the bracket, and the anchor nut is screw-locked on the top of the anchor rod.
  • the locking bracket with anchor is placed on the surface of the stratum or rock drilled hole, and a backing plate and a prestressed locking nut are placed on the top of the locking bracket; and together with the anchoring structure at the top end of the anchor rod The floor of the building is poured together.
  • the post-tensioning pre-stress applying device of the anchor rod has two structures. One is a device for applying upward force at the lower end of the steel bar holder, including a jack 6; the other is at the upper end of the steel bar holder.
  • Upward force equipment including but not limited to jacks, manual wrenches, cranes, hummingbirds, gantry cranes, wheel disks, etc., electric, hydraulic, pneumatic machinery and manual equipment.
  • the steel bar (main bar) is especially the fine-rolled screw steel, and the bonded or unbonded steel bar is adopted.
  • the shaft of the anchor rod with an enlarged head at the bottom end of the anchor rod exerts better stress
  • the bottom end of the anchor rod has an enlarged head or a straight-through equal-diameter non-expanded head anchor rod .
  • the post-tensioning prestressing device of the anchor rod can improve and strengthen the soil around the pile head to increase its bearing strength.
  • the anchor rod can be selected from concrete or high-grade cement slurry and steel frame to form a high-strength rigid anchor rod body, and a concrete structure with reinforcing ribs 13, such as a reinforced cage , Spiral stirrups, etc.
  • the use includes but not limited to the selection of various reinforcement materials, increasing the cross-sectional area, and increasing the strength and specifications of cement and concrete, etc.
  • various reinforcement materials include but not limited to several vertical bars, stirrups, steel sleeves, and steel cages , Steel wire mesh cage, pile end indirect reinforcement, bearing plate, anchor plate, bearing flange, etc., the reinforcement material is wrapped with one of the concrete or cement mortar, cement paste or other curable materials and solidified to form the anchor rod body .
  • the construction method of overcoming the deformation of the anti-floating straight-through equal-diameter non-enlarged head anchor rod or the enlarged head anchor rod system arranges anchor pads in the pile section, thereby post-tensioning Method to apply prestress.
  • the anchoring structure set at the top of the main bar of the anchor rod is poured together with the bottom of the building to form a floating, tensile or compressive system.
  • the anchoring structure at the upper end of the anchor rod adopts a three-piece high-strength nut anchoring form, a three-way high-strength nut or flange anchoring structure or other traditional anchoring methods.
  • Flange nuts and tic-shaped steel mesh combined structure or other traditional anchoring methods are used to anchor the bottom plate, purlin, beam, etc.
  • This application relates to a pre-stressed concrete anchor pile and a construction method (post-tensioning method) of an enlarged head (especially an enlarged head of a variable-diameter steel cage).
  • This application uses on-site prestressing, that is, post-tensioning application, so that the bearing capacity of the anchor rod reaches the required pre-stress value for the design, completely reforming the anchor rod without concrete pouring products, using the applicant’s post-tensioning method to apply
  • the pre-stressing device can be accurately applied, which can greatly reduce the deformation of the free section of the expanded anchor rod, and can ensure that the anchor rod is directly in the state of receiving force and applying tension during application.
  • the application in construction is extremely reasonable.
  • the overall cost is not high, because it can reduce transportation costs, and the length of the anchor rod is easy to control on site.
  • the length of the anchor rods often needs to be processed.
  • the strength of the concrete structure can be reached by the pouring method.
  • the strength above C30 (or higher strength) is far better than the pouring strength of mortar or mortar; when it is stretched, the construction of this scheme is simple and basically has no effect on the construction of the foundation.
  • the post-tensioned prestressed concrete anchor (pile) is Revolutionary. Prestressed concrete anchor rods (piles) play a positive role in improving the safety, stability and durability of anchor rod technology.
  • Figure 1 is a process flow diagram of the post-tensioning method of the application
  • Figure 2 is a schematic diagram of the structure and the device of the bolt expansion head after the application process is successful
  • Figure 3 is a schematic diagram of the second device with the structure and the bolt expansion head after the application process is successful;
  • Fig. 4 is a schematic diagram of the third device with the structure and the bolt expansion head after the application process is successful;
  • Fig. 5 is a schematic diagram of the structure of the device for applying prestress by the post-tensioning method of this application;
  • Fig. 6 is a schematic diagram of the structure of the device for applying prestress by the post-tensioning method of this application;
  • Fig. 7 is a schematic diagram of the structure of the device for applying prestress by the post-tensioning method of this application.
  • FIG. 8 is a schematic diagram of the structure of the device for applying prestress by the post-tensioning method of this application.
  • Figure 9 is the pouring structure of the applied bolt expansion head
  • Fig. 10 is a schematic cross-sectional view of Fig. 9;
  • Figure 11 is a schematic diagram of the overall structure of the prestressed concrete anchor rod (pile) of the enlarged head of the application;
  • Fig. 12 is a schematic diagram of an anchoring case in the D area of Fig. 11.
  • Rebar holder (the simplest way is composed of fixing nut 8, force clamp 9, internal penetration cylinder 6 and fixing nut 8), rebar (main reinforcement) 1, expansion head 2, bracket Plate 3, locking nut 4, anchor rod pouring body 5, inner-piercing cylinder 6, bracket 7, fixing nut 8, force clamp 9, and force applying machine 10.
  • the support plate 3 is placed on the reinforced soil.
  • the pipe sleeve 14 may be an outer shell of an unbonded steel bar oil coating layer, or a mesh steel bar 15.
  • Pile end prestressed anchor plate (anchor bracket pad) 3, prestressed pile end elevation 21.
  • the support plate 3 is placed on the reinforced soil body 12, and the surfaces of various locking supports 3-1 are provided with steel perforations.
  • Figures 2-4 show the complete structure and application structure of this application, the structure of the expanded diameter steel cage and the method of applying release and the method of constructing holes (including drilling tools, please refer to the applicant’s previous patent application) );
  • the anchor rod body is made of C30 concrete (or other high-grade concrete); the anchor rod body with an enlarged head 2 at the bottom of the anchor rod exerts better stress, and the enlarged head 2 can be anchored at the bottom end of the anchor after pre-casting Afterwards, prestress is applied to the steel bars.
  • prestress is applied to the steel bars.
  • Use a variety of prefabricated prestressed locking brackets and can be integrated with the cushion or with the bottom plate when pouring the concrete bottom plate.
  • Figure 5-8 is a schematic diagram of the application of prestressing structure; respectively represents the two structures of the force applying machine 10.
  • Figure 5-8 is a device that applies force upward at the lower end of the steel bar holder, including jacks and internal perforated cylinders 6; The other is a device that applies force upward on the upper end of the steel bar holder.
  • jacks two ordinary jacks can be prepared as a pair of upward dynamic lifting steel bars and stress Structure
  • manual wrenches etc.
  • the other is equipment that applies force upwards on the upper end of the steel bar holder, including but not limited to jacks, manual wrenches, cranes, hulus, gantry cranes, wheel disks, etc., electric, hydraulic, pneumatic machinery And manual equipment.
  • the locking bracket has various structures.
  • a backing plate and pre-stressed locking nut can be placed on the top, and the locking nut is tightened after the stress is applied.
  • the locking bracket and the anchoring structure at the uppermost end of the anchor rod are poured together with the building bottom plate, pre-stressed Will not be released.
  • Concrete anchor piles are formed by adding concrete and reinforcing steel skeleton to the anchor rod steel bars, and the concrete anchor piles are constructed with reinforced ribs 13, such as reinforced cages, vertical bars, spiral stirrups, etc.
  • the diameter of the ordinary section of the anchor rod (reinforced steel bar is poured with concrete) is increased (to 250mm or more), and used as a rigid concrete micro-pile 7.
  • Anchor pads are arranged in the pile section, so that the post-tensioning method applies prestress.
  • the prestress that can be applied to the pile body of the project of this embodiment is not more than 500KN.
  • the supporting torque wrench is also used to apply prestress through the upper fixing nut; for equipment with perforated rebar, the rebar holder mainly includes a fixing nut 8 and a force clamp 9.
  • the matching torque wrench is pre-stressed, and the oil cylinder, push rod, winch, wheel dial, lever, wrench, crane, hoist, hoist can be used; manual, electric, hydraulic, and pneumatic are not beyond the scope of protection of this application.
  • the inner-penetrating oil cylinder 6 and the fixing nut 8 form a steel bar holder 9, and the fixing nut 8 fixes the main rib of the anchor rod above the inner-penetrating oil cylinder 6.
  • a pre-stressed nut is set above the steel backing plate, which is mechanically connected with the backing plate and pre-stressed tendons, and the pre-stressed nut is tightened in time, and the pre-stress is applied with a matching torque wrench; the spiral stirrup and the foundation floor steel bar are bound, in the process of lashing Avoid collisions with prestressed steel bars and cause prestress loss; finally, according to the requirements of engineering design and specifications, the anchoring structure set at the top 13 of the main bar of the anchor rod is poured together with the building floor to form an anti-floating, tensile or compressive system .
  • Figure 11 is a schematic diagram of the overall structure of the enlarged head prestressed concrete anchor (pile) of the application: unbonded prestressed finish rolled threaded steel component A, finish rolled threaded steel supporting connector B, enlarged head section fine stone concrete crystal body C, applied After prestressing, the top of the anchor rod and the bottom plate are anchored to indicate D, the variable diameter steel cage E, and the ordinary section (free section) fine stone concrete crystal F.
  • a pre-stressed nut is set above the anchor backing plate, which is mechanically connected with the backing plate and pre-stressed tendons, and the pre-stressed nut is tightened in time after the pre-stress is applied, and the pre-stress is applied to the deformed position required by the design with a matching torque wrench, or a jack, Or use other machinery described in this application to apply prestress to the load required by the design, and lock it with anchors.
  • prestressed nuts can also be used for secondary tension locking to avoid collisions with the prestressed reinforcement during the lashing of the slab reinforcement.
  • the post-tensioning method is adopted to apply prestress, which can greatly reduce the displacement of the expanded anchor rod in practice.
  • the construction of this scheme is simple and has basically no impact on the construction of the foundation. It has a positive effect on improving the safety, stability and durability of the expansion bolt technology and engineering quality.
  • MXL-150D rotary engineering drilling rig (the examples are not limited to the brand specifications of the listed equipment); Genergy high-pressure grouting pump XPB-90C;
  • Mixers and multifunctional fine stone pumps; air compressors; (variable diameter) steel cage skeletons can adopt the steel cages of various structures previously applied for in this application, especially variable diameter steel cages.
  • the hole position datum line is ejected on the base layer.
  • the anchor rod position is determined by the method of inserting reinforcement to make the mark, and the white gray mark is scattered, and the anchor rod plane positioning deviation should not be greater than 100mm. Notify the supervisor and the owner's on-site personnel to conduct a review and acceptance.
  • the anchor rod position is determined according to the baseline and marked by the method of inserting reinforcement, and the supervisor and the owner’s on-site personnel are notified for recheck and acceptance.
  • Rotary jet lifting speed is 10-20cm/min, rotating speed is 10-20 revolutions/min.
  • the jet blasting medium can be changed from water to cement slurry.
  • the hole is drilled by the diameter of the drill bit at the front end. Therefore, the pressure is set to normal pressure, and the hole is drilled to the bottom of the hole and overdrilled by 500mm; , Experience or test pile results, adjust the pressure to the required pressure and carry out high-pressure spinning reaming (or reaming by other methods, for rock or gravel, the applicant has applied for a variety of drill bits earlier).
  • the hole expansion adopts pure cement slurry (or water), and ordinary Portland cement with cement strength not less than 42.5.
  • the nozzle rotates at a constant speed, and the high-pressure spray reaming is carried out at a lifting speed of 20cm/min and a rotation speed of 20r/min, and the hole is reamed at a constant speed from the bottom to the top for 2 times; when the water reaming process is adopted, the cement slurry expansion shall be used at the end. Hole again.
  • the injection pressure is determined according to the geological survey, experience or preliminary test piles.
  • the length of the expanded hole is calculated by measuring the length of the drill pipe.
  • the jet shall not be interrupted; once the jet is interrupted, the overlap length shall not be less than 500mm and the interval time shall not be greater than 30min when jetting again. Reduce the drilling speed after entering the rock formation in the high jetting section. Increase injection pressure.
  • the high-pressure jet water should be filtered through a filter, and the mud and cement slurry should be stirred twice and filtered during the mud transfer process to prevent pipe blockage accidents and affect the normal construction progress.
  • Elevation control After excavation at the construction site, use a level to measure the elevation of each work surface, calculate the length of the empty hole of each anchor rod hole, and mark it on the anchor feeder.
  • the residual slag in the hole is removed.
  • the on-site engineer and quality inspector shall measure the hole depth and anchor hole deflection. After the design requirements are met, the next process should be carried out as soon as possible.
  • the production and storage of the anchor pile body is carried out in the on-site steel bar processing shed.
  • the main rib is sleeved with a matching long corrugated pipe, filled with anti-corrosion grease and sealed (also: anti-corrosion grease layer is applied through the anti-corrosion grease layer device, and the anti-corrosion grease layer is coated without adhesive ribs.
  • Polypropylene plastic film, and then a plastic sleeve (pipe) is molded by a cooling cylinder; the corrugated tube and the centering bracket are bound firmly (a centering bracket is placed on the rod body every two meters according to the specification), and the anchor rod body is pressed
  • the material is cut according to the design requirements or the required length of the rock hole depth.
  • the high-strength steel bars of the anchor rod body are connected by high-strength connectors and are strictly prohibited from welding, and are made in strict accordance with the design requirements and specifications.
  • the quality of the anchor pile system should be checked again to ensure that the assembly meets the design requirements.
  • use a drilling rig to lift or manually lift the anchor piles into the hole along the wall of the hole for anchoring.
  • the fine stone concrete conveying pipe, steel wire rope and anchor pile are placed in the hole simultaneously; the anchor pile is inserted
  • the inner length of the hole should not be less than 95% of the design stipulation.
  • the anchor rod shall not be knocked at will or lifted at will.
  • variable diameter steel cage anchor pile After the variable diameter steel cage anchor pile is installed to the design elevation, control the verticality (hole slope ⁇ 1.0%), and then use a mechanical hoist or manually pull out the variable diameter switch pin to release the constraint; no pause in the middle, ensure that the steel cage is once Sexually open. Then it is ready to pour fine stone concrete.
  • the sand for underwater concrete pouring should be mixed medium sand mixed medium sand (extra-fine sand and artificial sand each 3:7); the particle size of coarse aggregate should be 5-12mm (depending on the chosen pouring equipment);
  • Underwater pouring concrete should be mixed with admixtures.
  • the wall thickness of the conduit should be 3-5mm, and the outer diameter should be 68 ⁇ 70mm; the diameter production deviation should not exceed 2mm, and the section length of the conduit should be determined according to the process requirements.
  • the length of the bottom pipe should not be less than 4m, and the joint should be double. Threaded square buckle quick connector;
  • the catheter should be assembled and pressure tested before use.
  • the test water pressure can be 0.6 ⁇ 1.0MPa;
  • the water-proof plug used should have good water-proof performance and ensure smooth drainage; the water-proof plug should be made of bladder or fine-stone concrete with the same strength level as the pile body concrete.
  • the buried depth of the pipe into concrete should be 2 ⁇ 6m. It is strictly forbidden to lift the catheter out of the concrete pouring surface, and the speed of raising the pipe should be controlled. A dedicated person should measure the buried depth of the pipe and the height difference between the concrete pouring surface inside and outside the pipe, and fill in the underwater concrete pouring record;
  • the last pouring volume should be controlled, and the height of overfilling should be 0.8 ⁇ 1.0m. After removing the flooding, it is necessary to ensure that the concrete strength of the exposed pile top reaches the design level.
  • the indirect steel mesh is placed in the center of the anchor pile head and lower than the elevation of the bottom plate surface, so that the indirect steel mesh is completely wrapped by the concrete slurry. Please refer to the detailed design drawing for the size of the indirect steel mesh and the buried elevation.
  • the flooding is removed and leveled to the elevation of the anchor pile construction surface, and the pre-stressed tension lock is implemented according to the design requirements.
  • the rated pressure of the loading device (jack, oil pump) used for the test must be greater than the type test pressure.
  • Test measuring instruments pressure gauge, dynamometer, displacement gauge
  • the anchoring structure set at the top of the main reinforcement of the anchor rod is poured together with the bottom of the building to form a floating, tensile or compressive system.

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Abstract

本申请提供一种扩大头预应力混凝土锚杆施工工法，由锚杆骨架体系与预应力混凝土灌注凝固而成的锚杆；其具体施工实施步骤是，钻孔定位；钻孔钻进至设计深度，开展旋喷或机械扩孔施工并成孔，下放锚杆的拉杆即主筋与扩大头骨架或固定直径锚头骨架；锚杆的拉杆即主筋与扩大头，扩大头骨架到位后，扩大机构将扩大头扩大至设计尺寸，然后灌注混凝土在扩大头即扩体段和非扩体段成型，至设计和规范要求的额定强度后；锚杆中拉杆即主筋采用能施加预应力的装置和方法对主筋施加预应力；施加设计和规范要求的预应力,完成后并锁定，再撤消需要撤除的预应力施加的设备装置；锚杆的整体部分由浇筑的混凝土与锚杆骨架体构成。

Description

一种扩大头预应力混凝土锚杆施工工法 技术领域
本申请涉及固定直径或扩大头预应力混凝土锚杆及施工工法，是一种克服抗浮固定直径或扩大头锚杆杆体自由段弹性变形的锚杆应用装置，也涉及变直径钢筋笼扩大头预应力混凝土锚杆桩及施工工法(后张法)。
背景技术
本申请人的CN2020103929335一种锚杆的后张预应力施加装置，包括施力机械10、支架或/与支架板、钢筋夹持器、支架或支架板中央设有能使锚杆的上端钢筋(主筋)穿过的孔洞；锚杆钢筋的下端固定在锚杆地层或岩层的钻孔内，穿过的孔洞后上端钢筋由钢筋夹持器夹持，并由施力机械10施加应力，施加到额定应力时(也可以根据相对伸长进行估值或用应力计测量)，上端钢筋的通过锁定螺母或焊接等方式固定在支架板上，再在钻孔内此钢筋(主筋)的周围浇筑混凝土。钢筋(主筋)尤其是采用精轧螺纹钢。锚杆在地层或岩层钻孔的表面设有的支架7为锚杆，孔洞后上端钢筋由钢筋夹持器。支架带有支撑脚，支架孔洞的下方为锁锚螺母螺接在精轧螺纹钢。带锚的锁定支架在地层或岩层钻孔的表面，锁定支架上方放置垫板和预应力锁定螺母；并和锚杆最上端的锚固结构一起与建筑物底板一并浇筑。但未涉及扩大头或固定直径或预应力混凝土锚杆(桩)的施工工法。
众所周知，砂石水泥三合一混凝土比砂浆的强度高许多倍，如标号c30混凝土强度达到30MPa以上；成本并不高，只要采用普通水泥。
CN 107044122是发明人提出的一种克服抗浮固定直径或扩大头锚杆体系变形(杆体自由段弹性变形和固定直径或扩大头锚固段的土体蠕变变形)的工法，通过新的后张法施加预应力，从而达到控制承压型固定直径或扩大头锚杆工程实践中变形量的目的。通过对这两部分变形的分析，提出一种新型的解决直通或扩大头锚杆变形的工法。承压型固定直径或扩大头锚杆预应力工法，钻孔钻进至设计深度，能够开展旋喷施工或机械扩孔施工，放下锚杆的拉杆与固定直径锚头或扩大头(变直径钢筋笼或各种囊式扩大头、以及各种扩大头等)，扩大头到位后扩大机构将扩大头扩大至设计尺寸。
本申请人先期提出的方法解决抗浮锚杆基本解决变形问题，工程实际表明：承压型固定直径或扩大头锚杆的位移由杆体的弹性变形和扩体段的滑移(塑性变形)两部分组成。
锚杆扩体段的塑性变形及残余变形，与扩体段承受的端压力有关以及所在土层性质相关，与杆体采用的钢筋根数无关。锚杆自由段杆体的弹性变形控制，杆体的弹性变形即钢筋的弹性变形主要由杆体钢筋的截面积、钢筋的弹性模量以及杆体的长度控制。
发明内容
本申请目的是，由锚杆骨架体系与预应力混凝土灌注凝固而成的锚杆(桩)，提出一种由锚杆骨架体系与预应力混凝土灌注凝固而成的锚杆(桩)，并用后张预应力施加装置，通 过简明和有效的装置，在现场施工时能够施加预应力(与预制预应力锚杆相比较，本申请应用预应力混凝土灌注凝固锚杆骨架体系，并用后张预应力的施加，从而消除锚杆的变形量，可以很好的减少工程锚杆的位移，锚杆体拉裂，增加锚杆的安全和稳定性。
本申请的技术方案是，由锚杆骨架体系与预应力混凝土灌注凝固而成的锚杆(桩)，并用施加装置用后张法施加预应力，其施工实施步骤是，钻孔定位；钻孔钻进至设计深度，开展旋喷或机械扩孔施工并成孔，下放锚杆的拉杆即主筋与扩大头骨架或固定直径锚头骨架；锚杆的拉杆即主筋与扩大头(变直径钢筋笼或各种囊式扩大头、以及各种扩大头等)，扩大头到位后，扩大机构将扩大头扩大至设计尺寸，然后灌注混凝土在扩大头即扩体段和非扩体段成型，至设计和规范要求的额定强度后；锚杆中拉杆即主筋采用能施加预应力的装置和方法对主筋(如带套管的无粘结预应力精轧螺纹钢筋、普通三级钢筋、钢绞线等)施加预应力(无粘结才便于后施加应力；施加设计和规范要求的预应力,完成后并锁定(如螺母锁定、焊接等)，再撤消需要撤除的预应力施加的设备装置；锚杆的整体部分由浇筑的混凝土与锚杆骨架体构成；锚杆的整体达到额定强度后，依据工程设计和规范的要求，锚杆主筋的顶端所设置的锚固结构，与建筑物底板一并浇筑，形成抗浮抗拉或抗压体系。也可以根据工程设计和规范的要求，不用施加预应力与建筑物底板浇筑。例如：锁定支架3-1并和锚杆最上端的锚固结构一起与建筑物底板一并浇筑，也可以预应力不施加一并与建筑物底板浇筑。
预应力抗浮抗拉锚杆钢筋，包括主筋钢筋(包括主筋钢筋或将主筋钢筋通过连接螺母的主筋钢筋连接结构)作为基本承力的结构，主筋钢筋为精轧无粘结钢筋，主筋钢筋表面设有防腐油脂层，防腐油脂层外设有塑料薄膜套；通过涂防腐油脂层装置涂防腐油脂层，涂防腐油脂层无粘结筋通过塑料挤压机涂刷聚乙烯或聚丙烯塑料薄膜，再经冷却筒模成型塑料套管，套管可以是金属、PP、PE、PVC、塑料等各种材质的套管；在塑料套外采用包括混凝土或水泥砂浆、水泥浆或其他能固化材料包裹并凝结固化；预应力后施加在主筋钢筋(固定完成后施加预应力)，形成预应力锚杆杆件；将主筋钢筋，用螺母锁定，张拉钢筋施加预应力后，形成预应力锚杆杆件；预应力锚杆杆件可以是施工现场浇筑的，亦可以是工厂预制生产的。
锚杆主筋钢筋，施加后张预应力锚杆组件内钢筋的数量，是一根或者一根以上，但一般不多于15根(否则成混凝土桩了)，钢筋的规格、性能、强度、直径可根据设计要求确定；预应力锚杆组件的长度、横截面的形状和面积，则根据工程技术要求设定；当工程需要杆件的长度超长时，可以采取用螺母连接器的方式或其他方式，将两根或两根以上的钢筋杆件加以连接，以达成所需的长度；钢筋螺母连接器也可以预先埋设在锚杆内，钢筋可以选用圆钢、钢管、钢绞线和其他型钢，型钢两端亦可以设有丝纹。
锚杆组件和可变径钢筋笼，立体几何形态包括但不限于：立方体、多面体、正多面体、四面体、长方体、圆柱、圆台、棱柱、棱台、圆锥、棱锥、竹节状、串状、凸凹状，；平面横截面的形状包括但不限于：正方形、长方形、三角形、四边形、菱形、梯形、多边形、圆、椭圆、圆环、扇形、弓形；锚杆组件可以是实心的，亦可以是空心的截面。
抗浮抗拉锚杆用预制预应力无粘结钢筋，及其加长形态的主筋和配筋可选用的材料，包括但不限于钢材、钢绞线、玻璃纤维、树脂、玻璃纤维增强树脂、芳纶纤维、碳纤维、石墨烯、碳元素相关的材料及其复合材料、高分子、高分子聚合物材料、纳米材料、金属材料和非金属材料。
砂石水泥三合一混凝土中，常见采用与水搅拌成符合工程设计规范的预应力细石混凝土，细石的直径中一般在13毫米以下，砂、细石、水泥与水搅拌成符合工程设计规范的预应 力细石混凝土，细石的粒径及砼配合比例，需满足设计和规范要求。
钻孔前完成主体结构底板浇筑，主体结构底板浇筑完成以后，在底板上开槽，通过底板作为施加预应力的支点，再进行预应力混凝土锚杆桩施工工法，对钢筋施加预应力完成锚杆浇筑后，最后在开槽处浇筑混凝土完成锚杆与主体结构底板锁定，(由于对底板的影响较大，此种方法一般不常见采用)。
亦可以锚杆非扩大头段的顶面作为施加预应力的支点，待混凝土强度达到不低于设计和规范要求的可施加预应力的强度后，凿除泛浆找平至锚杆桩顶面施工面标高，根据设计要求实施预应力张拉锁定。也可根据工程设计需要设定。
可选择满足工程施工和设计质量要求的各种型号规格的灌注设备。浇筑混凝土浇筑管的内径一般采用4-10cm(也可根据工程设计需要和钻孔孔径的大小设定)，用以浇筑或高压浇筑由砂、细石、水泥与水搅拌成符合工程设计规范的预应力细石混凝土。
锚杆主体强度明显增大，可以采用先浇筑扩大头，尤其是带变直径钢筋笼的扩大头，也用混凝土浇筑，扩大头的强度足以满足施加预应力的要求，并在锚杆主筋底部在拉力固定端。
施加预应力的步骤：
(一)以底板作为施加预应力的支点
①基坑开挖至基底并清理浮浆且找平(亦可在垫层施工完成后操作此步骤)，在找平后的锚杆顶部放置遇水膨胀止水胶条；
②浇筑底板混凝土，在底板开槽或预留孔道端埋入锚垫板(施加预应力用)，埋入锚垫板前再放置一道遇水膨胀止水胶条；
③锚垫板上方螺纹钢筋上设置预应力螺母，与垫板、预应力钢筋机械连接，并及时旋紧预应力螺母，并用配套扭力扳手施加预应力至设计要求的变形位置。或用千斤顶施加预应力至设计要求的荷载，用锚具锁定。
(二)以锚杆桩顶作为施加预应力的支点
①在锚杆的混凝土或注浆体强度达到90％以后，清理锚杆桩顶设计标高以上的浮浆，并用水泥砂浆找平，在锚杆顶部埋入锚垫板；
②在锚垫板上方螺纹钢筋上设置预应力螺母，与垫板、预应力钢筋机械连接，并及时旋紧预应力螺母，并用配套扭力扳手施加预应力至设计要求的变形位置。或用千斤顶等或其他种设备，施加预应力至设计要求的荷载，用锚具锁定。
③锚垫板及锁定预应力用的螺母均刷防腐漆；
④浇筑垫层，再在垫层上端底板下端放置遇水膨胀止水胶条；
⑤预应力螺母上施加保护装置指螺旋箍筋套在预应力螺母上，绑扎螺旋箍筋以及基底上的基础底板钢筋，绑扎过程中避免碰撞预应力钢筋；
⑥安装锚固配件；根据工程设计和规范的要求，在锚杆主筋的顶部所设置锚固结构
⑦最后支模浇筑基础混凝土基础底板，与建筑物底板一并浇筑，形成抗浮抗拉或抗压体系。
本申请通过细导管(外径一般不超过150毫米)浇注混凝土，将锚杆自由段直径控制在180～300mm结构，也能作为刚性微型桩；
锚杆的整体部分，如果选用高标号的水泥砂浆或水泥浆与锚杆骨架体构成，并能够满 足设计与规范要求，也是可行的。
本申请采用预应力抗浮抗拉锚杆，包括主筋钢筋(包括主筋钢筋或将主筋钢筋通过连接螺母的主筋钢筋连接结构)作为基本承力的结构，尤其是主筋钢筋为精轧无粘结钢筋，主筋钢筋表面设有防腐油脂层，防腐油脂层外设有塑料薄膜套；通过涂防腐油脂层装置涂防腐油脂层，涂防腐油脂层无粘结筋通过塑料挤压机涂刷聚乙烯或聚丙烯塑料薄膜，再经冷却筒模成型塑料套(管)；在塑料套外采用本申请方法包括混凝土或(水泥砂浆、水泥浆或其他能固化材料)并凝结固化；预应力后施加在主筋钢筋(后施加预应力、混凝土固化完成再释放预应力)，形成预应力锚杆杆件；将主筋钢筋用螺母锁定，对钢筋施加预应力后，形成预应力锚杆杆件。
在锚杆自由段即锚杆体达到设计要求的强度后成为后张法施加预应力的锚杆，在锚杆顶部即刚性微型桩顶部放置锚垫板，锚垫板放置完成后，锚杆钢筋顶端通过螺母与垫板、预应力筋机械连接。
锚杆的后张预应力施加装置包括施力机械、支架或/与支架板、钢筋夹持器或锁定螺母、支架或支架板中央设有能使锚杆的上端钢筋穿过的孔洞；锚杆钢筋的下端固定在锚杆地层或岩层的钻孔内，穿过的孔洞后上端钢筋由钢筋夹持器夹持或螺母锁定，并由施力机械施加应力，上端钢筋的通过锁定螺母或焊接等方式固定在支架板上所述的锚杆的后张预应力施加装置，锚杆在地层或岩层钻孔的表面设有锚杆的后张预应力锁定支架，锁定支架可以是预制的也可以是现场制作的，其形状包括但不限于带支撑脚或不带支撑脚的长方体、正方体、圆柱体、多面体混凝土或钢制件。
所述的锚杆的后张预应力施加装置，预应力锁定支架带有支撑脚，锚杆主筋精轧螺纹钢穿过支架孔洞，在其上方用锁锚螺母螺锁定。
所述的锚杆的后张预应力施加装置，带锚的锁定支架在地层或岩层钻孔的表面，锁定支架的上方放置垫板和预应力锁定螺母；并和锚杆最上端的锚固结构一起与建筑物底板一并浇筑。
所述的锚杆的后张预应力施加装置，施力机械有两种结构，一是使在钢筋夹持器下端向上加力的设备，包括千斤顶6；另一种是在钢筋夹持器上端向上加力的设备，包括但不限于千斤顶、手动扳手、吊车、胡芦、龙门吊、轮旋盘等，电动、液压、气压机械和手动设备。
所述的锚杆的后张预应力施加装置，钢筋(主筋)尤其是采用精轧螺纹钢，采用有粘结或无粘结的钢筋。
所述的锚杆的后张预应力施加装置，锚杆钢筋底端具有扩大头的锚杆钢筋的杆身施加应力更好，锚杆钢筋底端具有扩大头或直通等直径非扩大头锚杆。
所述的锚杆的后张预应力施加装置，并可对桩头周围土体进行改良加固，增加其承载强度。
所述的锚杆的后张预应力施加装置，锚杆可选择混凝土或高标号的水泥浆及钢筋骨架形成高强度的刚性锚杆体，加有加强筋13的混凝土的结构，如加钢筋笼、螺旋箍筋等。
施加预应力的大小：根据地下室抗浮计算时，计算的上浮水头放大1.05倍；抗浮计算锚杆的安全系数取K＝2.0；因此锚杆施加的预应力小于锚杆的特征值(最大变形长度)，且要大于常水位时所需要的锚杆抗浮力，综合考虑取施加预应力的大小，应根据设计和有关规 范的要求确定。
提高注浆体材料的强度，将其作为刚性微型桩，在锚杆自由段注浆体达到设计要求的强度后，在锚杆顶部放置锚垫板，后张法施加预应力。
通过将锚杆自由段直径加大(增至200～300mm，或更大，浇注混凝土等方式)，使用包括但不限于选用各种配筋材料、增加截面积、增加水泥和混凝土强度与规格等方法，增加锚杆体及其桩端段的承载强度，及对其周围的土体加固增加土体强度；各种配筋材料包括但不限于若干竖钢筋、箍筋、钢套筒、钢筋笼、钢丝网笼、桩端间接配筋、承压板、锚固板、承压法兰等，配筋材料与混凝土或水泥砂浆、水泥浆或其他能固化材料包裹之一并凝结固化形成锚杆杆体。
通过施加预应力，从而消除锚杆的变形量，可以很好的减少工程锚杆的位移。综合考虑，在保证桩身强度以及桩抗压承载力的前提下，克服抗浮直通等直径非扩大头锚杆或扩大头锚杆体系变形的工法，在桩段布置锚垫板，从而后张法施加预应力。
施加设计和规范要求的预应力,完成后并锁定，再撤消需要撤除的预应力施加的设备装置；锚杆的整体部分由浇筑的混凝土与锚杆骨架体构成；锚杆的整体达到额定强度后，根据工程设计和规范的要求，锚杆主筋的顶端所设置的锚固结构，与建筑物底板一并浇筑，形成抗浮抗拉或抗压体系。锚杆杆上端的锚固结构采用高强螺母三件套锚固形式、三通高强螺母或法兰锚固结构或其他传统锚固方式。法兰螺母加井字形钢筋网组合结构或其他传统锚固方式与底板、围檩、梁等进行锚固。
现有技术包括本申请人已经申请获得的技术，一般都是灌注水泥浆或水泥砂浆(凝固后强度远不够)，解决不了或很难解决锚杆的预应力及其施加，以达到规范要求和确保工程安全性、稳定性、耐久性的问题，从而使传统锚杆技术的安全性、稳定性、耐久性等方面存在着安全隐患。为解决这一问题，本申请针对性地提出一种扩大头(特别是变直径钢筋笼扩大头)预应力混凝土锚杆桩及施工工法(后张法)。本申请主要用于建筑地下室抗浮基坑支护，边坡支护，以及加固等技术范畴，也用于抗压桩。
有益效果：本申请涉及一种扩大头(特别是变直径钢筋笼扩大头)预应力混凝土锚杆桩及施工工法(后张法)。本申请通过现场的预应力施加，即后张应用，使其锚杆承载力达到设计所需要的施加预应力值，完全改革了锚杆无混凝土浇筑的制品，利用本申请人的后张法施加预应力装置能够精确施加，可以大大减小扩体锚杆自由段的变形量，可以保证锚杆应用时直接处于受力并施加拉力的状态，在建筑上应用极为合理，而且本申请与预制预应力锚杆相比较，总体成本不高，因为能够减少运输成本，锚杆的长度易在现场控制，采用预制锚杆时往往锚杆的长度还要进行处理，采用混凝土结构的浇筑法强度能够达到C30(或更高强度)以上的强度，远优于砂浆或灰浆的浇筑强度；在拉伸时同时本方案施工简单，对基础的施工基本无影响，后张预应力混凝土锚杆(桩)是革命性的。预应力混凝土锚杆(桩)对于提高锚杆技术的安全性、稳定性、耐久性，有着积极的作用。
附图说明
图1为本申请后张法工艺流程图；
图2为本申请工艺成功后结构连同锚杆扩大头的装置示意图；
图3为本申请工艺成功后结构连同锚杆扩大头的第二种装置示意图；
图4为本申请工艺成功后结构连同锚杆扩大头的第三种装置示意图；
图5为本申请后张法施加预应力的装置结构示意图；
图6为本申请后张法施加预应力的装置结构示意图；
图7为本申请后张法施加预应力的装置结构示意图；
图8为本申请后张法施加预应力的装置结构示意图；
图9为本申请锚杆扩大头浇筑结构；
图10为图9的横截面示意图；
图11为本申请扩大头预应力混凝土锚杆(桩)总体结构示意图；
图12为本图11之D区的一种锚固案例的示意图。
具体实施方式
如图2-3所示：钢筋夹持器(最简明的方式由固定螺母8、受力夹9、内穿式油缸6与固定螺母8构成)，钢筋(主筋)1、扩大头2、支架板3、锁定螺母4、锚杆浇筑体5、内穿式油缸6、支架7、固定螺母8、受力夹9、施力机械10。支架板3放置在加固后的土体上。管套14可以是无粘结钢筋涂油层的外套、网片钢筋15。桩端预应力锚板(锚固支架垫板)3、施加预应力桩端标高21。自由(普通)段钻孔孔径16、灌注口17，网片钢筋15与桩端预应力锚板(支架垫板)3的连接点18。应力计11。支架板3放置在加固后的土体12上、各种锁定支架3-1的表面上设有钢筋穿孔。
图2-4表示了本申请的完整结构和应用上的结构，扩大直径的钢筋笼的结构与施加释放的方法以及施工成孔的方法(包括钻具均可参考本申请人的在先专利申请)；锚杆杆体采用C30混凝土(或其他高标号混凝土)；锚杆钢筋底端具有扩大头2的锚杆钢筋的杆身施加应力更好，扩大头2预先浇筑后可以在锚杆底端锚固后施加预应力在钢筋上。使用各种预制预应力锁定支架，并可以和垫层或在浇注混凝土底板时与底板一体化。
并可增加桩头周围土体加固或扩大头。图5-8为本申请预应力施加结构示意图；分别代表了施力机械10的两种结构，图5-8是使在钢筋夹持器下端向上加力的设备，包括千斤顶、内穿孔式油缸6；另一种是在钢筋夹持器上端向上加力的设备，向上加力的设备的种类极多，不超出杠杆原理的结构.
具体实施方式中有所列举施力机械有两种结构，一是使在钢筋夹持器下端向上加力的设备，包括千斤顶(两个普通千斤顶可以制备成一对向上的动力抬钢筋、施加应力的结构)、手动扳手等；另一种是在钢筋夹持器上端向上加力的设备，包括但不限于千斤顶、手动扳手、吊车、胡芦、龙门吊、轮旋盘等，电动、液压、气压机械和手动设备。
锁定支架有各种结构，上方可再放置垫板和预应力锁定螺母，在应力施加到位后由锁定螺母拧紧；锁定支架并和锚杆最上端的锚固结构一起与建筑物底板一并浇筑，预应力不会释放。
锚杆钢筋外加混凝土及钢筋骨架形成混凝土锚杆桩，混凝土锚杆桩加有加强筋13的混凝土的结构，如加钢筋笼、竖筋、螺旋箍筋等。
将锚杆普通段直径(螺纹钢筋外周浇混凝土)加大(增至250mm，或更大)，将其作为刚性混凝土微型桩7，在保证桩身强度以及桩抗压承载力的前提下，在桩段布置锚垫板，从而后张法施加预应力。
不考虑扩体段的端压力，假设杆体普通段可以提供的抗压承载力标准值(按照摩擦 桩考虑)约为500kn：桩身强度设计值为：N＝fc*As＝14.3x3.14x0.25x0.25/4*1000＝701.6KN
本实施例工程桩身可以施加的预应力不大于500KN。
1、施加预应力的步骤如下：
①基坑开挖至基底并清理浮浆；并施作遇水膨胀止水胶条；
②初步浇筑混凝土垫层，再在锚杆顶部，埋入带锚的锁定支架作为锚垫板(直径250mm，厚16mm)；在锁定支架上方设置支架，锁定螺母先拧在钢筋上，内穿式油缸6(或内孔式千斤顶)在支架上，内穿式油缸(或内孔式千斤顶)中央有孔穿过锚杆钢筋；内穿式油缸6(或千斤顶)在支架上方向上发力使主筋应力产生，再在支架下方固定锁定螺母。锚杆钢筋上拧有预应力锁锚螺母；
③也用配套扭力扳手通过上方的固定螺母施加预应力；钢筋穿孔的设备，钢筋夹持器主要包括固定螺母8、受力夹9。配套扭力扳手施加预应力，油缸、推杆、绞盘、轮旋盘、杠杆、板手、吊车、葫芦、吊机均可；手动、电动、液压、气动均没有超出本申请的保护范围。
也可以是内穿式油缸6与固定螺母8构成钢筋夹持器9，固定螺母8在内穿式油缸6上方固定锚杆的主筋。
与垫板、预应力筋机械连接，并及时旋紧预应力螺母，
④绑扎螺旋箍筋套住螺纹钢筋及预应力螺母以及基础底板钢筋，绑扎过程中避免碰撞预应力钢筋，造成预应力损失；最后，支模浇筑基础混凝土的底板(保证整体性良好)。[0078]钢垫板上方设置预应力螺母，与垫板、预应力筋机械连接，并及时旋紧预应力螺母，并用配套扭力扳手施加预应力；绑扎螺旋箍筋以及基础底板钢筋，绑扎过程中避免碰撞预应力钢筋，造成预应力损失；最后，根据工程设计和规范的要求，锚杆主筋的顶端13所设置的锚固结构，与建筑物底板一并浇筑，形成抗浮抗拉或抗压体系。图11为本申请扩大头预应力混凝土锚杆(桩)总体结构示意图：无粘结预应力精轧螺纹钢筋组件A，精轧螺纹钢筋配套连接器B，扩大头段细石混凝土结晶体C，施加预应力后锚杆顶部与底板锚固示意D，变直径钢筋笼E，普通段(自由段)细石混凝土结晶体F。
锚垫板上方设置预应力螺母，与垫板、预应力筋机械连接，并在预应力施加后及时旋紧预应力螺母，并用配套扭力扳手施加预应力至设计要求的变形位置、或用千斤顶、或用本申请所述的其它机械施加预应力至设计要求的荷载，用锚具锁定。
在绑扎基础底板钢筋前，也可以利用预应力螺母进行二次张拉锁定，底板钢筋绑扎过程中避免碰撞预应力钢筋，最后，根据工程设计和规范的要求，锚杆主筋的顶端所设置的锚固结构，与建筑物底板一并浇筑，形成抗浮抗拉或抗压体系。
通过采用的后张法施加预应力，可以大大减小扩体锚杆的实践中的位移量，同时本方案施工简单，对基础的施工基本无影响。对于提高扩体锚杆技术和工程质量的安全性、稳定性、耐久性，有着积极的作用。
扩大头预应力混凝土锚杆(桩)的施工
1、机械设备及产品规格
MXL-150D回转式工程钻机(实施例不限于列举的设备的品牌规格)；聚能高压注浆泵XPB-90C；
搅拌机和多功能细石泵；空气压缩机；(变直径)钢筋笼骨架可以采用本申请在先申请的多种结构的钢筋笼，尤其是变直径钢筋笼。
(预应力)杆件为精轧螺纹钢筋
2、不同地层条件下机械设备与产品的组合
Figure PCTCN2020129280-appb-000001
3、成孔
3.1施工工艺(图1)
3.2施工方法
3.21测量定位
按照现场已复核过的轴线，根据设计要求和地层条件，在基层上弹出孔位基准线。
根据基准线确定出锚杆位置采用插筋法作好标记，并撒白灰标记，锚杆平面定位偏差不宜大于100mm。通知监理、业主现场人员进行复核验收。
3.22钻孔(普通段)
根据基准线确定出锚杆位置采用插筋法作好标记，通知监理、业主现场人员进行复核验收。
锚杆钻机成孔：
1)孔位偏差≤100mm，孔斜率≤1.0％，孔径≥设计孔径。
2)旋喷提升速度10～20cm/min，旋转速度10～20转/min。
3)为防塌孔此时旋喷介质可由水改为水泥浆，此时依靠前端钻头直径进行钻孔，因此压力设为常压，钻至孔底并超钻500mm；待扩孔时根据地勘、经验或试桩结果将压力调至所需压力进行高压旋喷扩孔(或其它方法扩孔，对岩石或砾石本申请人已经申请在先的多种钻头)。
4)中断喷射后，恢复注浆时搭接长度≥0.5m。
3.23高压旋喷扩孔(根据不同的地质条件也可以选择不同的扩孔方式)
1)扩孔采用纯水泥浆(或水)，水泥强度不低于42.5的普通硅酸盐水泥。喷射时喷管匀速旋转，以20cm/min的提升速度及20r/min的转速进行高压喷射扩孔，由底往上匀速扩孔2遍；采用水扩孔工艺时，最后还应采用水泥浆液扩孔一遍。喷射压力根据地勘、经验或前期试桩进行敲定。
2)为了确保扩体段长度满足设计要求，采用测量钻进钻杆的长度来推算扩孔长度。
3)旋喷扩孔完毕后将钻杆提出孔外，立即用大量清水清洗钻机及高压泵及管路。
4)注意事项：
①喷射扩孔时，实时监测浆液状态、喷射流量、压力、钻杆转速及提升速度等施工参数，确保其符合设计要求。
②在高压喷射扩孔过程中，不得中断喷射；一旦出现喷射中断，再次喷射时，搭接长度不小于500mm，且间隔时间不大于30min。在高喷段进入岩层后降低钻进速度。提升喷射压力。
③高压喷射用水应经滤网过滤，泥浆及水泥浆应采用二次搅拌，并在泥浆转移过程中进行过滤，以防发生堵管事故，影响正常施工进度。
④标高控制施工现场开挖后用水准仪测量各做作业面的标高，计算出每个锚杆孔位的空孔长度，在送锚器上做标记。
⑤最终成孔后清除孔内余渣，同时现场工程师及质检员进行孔深、锚孔偏斜度测量，符合设计要求后应尽快进行下道工序施工。
⑥各机台施工人员必须认真填写钻孔钻进中原始记录表，详细记录各孔的进尺情况，地层变化及施工时的其它特殊情况。
进一步的，根据设计规范要求和工程土层状况，也可以机械干孔成孔和扩孔，并在干孔状态下灌注混凝土。
4、变直径钢筋笼扩大头锚杆桩组装与下放
4.1变直径钢筋笼扩大头锚杆桩组装
4.11锚杆桩杆体
锚杆桩杆体制作、存储在现场钢筋加工棚内进行。主筋套上与之匹配的通长波纹管，填充防腐油脂并密封(亦可：通过涂防腐油脂层装置涂防腐油脂层，涂防腐油脂层无粘结筋通过塑料挤压机涂刷聚乙烯或聚丙烯塑料薄膜，再经冷却筒模成型塑料套(管))；波纹管和对中支架之间绑扎牢固(按规范要求在杆体上每隔两米安放一个对中支架)，锚杆杆体按设计要求或根据入岩孔深要求的长度下料。锚杆杆体高强钢筋的搭接采用高强连接器连接严禁焊接，严格按设计要求和规范制作。
4.12锚杆桩的组装
1)将制作好的杆体穿过变直径钢筋笼中心管并用配套的高强螺母进行锁定，螺母超拧两丝；同时在变直径钢筋笼中心管顶部用限位螺母进行锁定防止钢筋笼上下滑动。
2)将细石砼导管沿着杆体至变直径钢筋笼穿插到底部(导管末端2m段也可采用软管)并安装导向帽(以不影响导向帽的安装为宜)，安装时注意不能影响到钢筋笼的弹开；上部细石砼输送管用扎丝与杆体进行轻微绑扎固定以不影响后期抽出为宜。
3)用细钢丝绳卸扣扣住变直径钢筋笼变直径开关销子，此时钢丝绳严禁拉扯。
4.2变直径钢筋笼扩大头锚杆桩的下放与打开
4.21锚杆桩的下放
锚杆桩放入钻孔前，应再次检查锚杆桩体系的质量，确保组装满足设计要求。经检验合格后采用钻机吊运或人工抬送沿孔壁将锚杆桩送入孔中进行下锚，下放时细石砼输送管、钢丝绳与锚杆桩同步放入孔内；锚杆桩插入孔内长度不应小于设计规定的95％，锚杆桩下放完成后，不得随意敲击锚杆，不得随意提拔。
4.22打开变直径钢筋笼
变直径钢筋笼锚杆桩安装到设计标高后，控制好垂直度(孔斜率≤1.0％)，然后用机械卷扬机或人工拔出变直径开关销子，解除约束；中间禁止停顿，确保钢筋笼一次性打开。然后准备灌注细石混凝土。
5、灌注细石混凝土
5.1水下灌注的混凝土应符合下列规定:
1)水下灌注混凝土必须具备良好的和易性,配合比应通过试验确定；坍落度宜为180～220mm；和
易性良好。无泌水、无离析现象，易泵送，易施工；28天抗压强度符合强度评定标准(GB/T50107-2010)；
2)水下灌注混凝土的砂宜选用混合中砂混合中砂(特细沙与人工砂各3:7)；粗骨料的粒径宜为5～12mm(根据所选用灌注设备来定)；
3)水下灌注混凝土宜掺外加剂。
4)采用的c30细石混凝土配合比设计见下表(或按设计规范要求配置细石混凝土)：
强度MPa
Figure PCTCN2020129280-appb-000002
5.2混凝土导管的构造和使用应符合下列规定:
1)导管壁厚宜为3-5mm,外径径宜为68～70mm；直径制作偏差不应超过2mm,导管的分节长度可视工艺要求确定,底管长度不宜小于4m,接头宜采用双螺纹方扣快速接头；
2)导管使用前应试拼装、试压,试水压力可取为0.6×1.0MPa；
3)每次灌注后应对导管内外进行清洗。
5.3隔水栓
使用的隔水栓应有良好的隔水性能,并应保证顺利排出；隔水栓宜采用球胆或与桩身混凝土强度等级相同的细石混凝土制作。
5.4灌注水下混凝土的质量控制应满足下列要求(根据设计规范要求和工程土层状况，也可以机械干孔成孔和扩孔，在干孔状态下灌注混凝土):
1)开始灌注混凝土时,导管底部至孔底的距离宜为300～500mm；
2)应有足够的混凝土储备量,导管一次埋入混凝土灌注面以下不应少于0.8m；
3)导管埋入混凝土深度宜为2～6m。严禁将导管提出混凝土灌注面,并应控制提拔导管速度,应有专人测量导管埋深及管内外混凝土灌注面的高差,填写水下混凝土灌注记录；
4)灌注水下混凝土必须连续施工,每根桩的灌注时间应按初盘混凝土的初凝时间控制,对灌注过程中的故障应记录备案；
5)应控制最后一次灌注量,超灌高度宜为0.8～1.0m,凿除泛浆后必须保证暴露的桩顶混凝土强度达到设计等级。
6、间接钢筋网片安装
混凝土灌注完成后将间接钢筋网片居中安放在锚杆桩桩头并低于底板面标高，使得间接钢筋网片完全被混凝土浆体包裹住。间接钢筋网片尺寸与埋放标高见设计大样详图。
7、张拉锁定与锚固
7.1张拉预应力的条件
混凝土强度达到不低于设计要求的强度90％后凿除泛浆找平至锚杆桩施工面标高，根据设计要求实施预应力张拉锁定。试验用加荷装置(千斤顶、油泵)的额定压力必须大于式验压力。试验用计量仪表(压力表、测力计、位移计)应满足测试要求的精度。
7.2锚固：张拉锁定结束后，即可在锚杆主筋的顶端13将止水环及锚固配件按设计说明进行安装。
7.3最后，根据工程设计和规范的要求，锚杆主筋的顶端所设置的锚固结构，与建筑物底板一并浇筑，形成抗浮抗拉或抗压体系。
以上所述仅为本申请的实施例，并不用以限制本申请，凡在本申请的精神和原则之内所作的任何修改、等同替换和改进等，均以包含在本申请的保护范围之内。

Claims (10)

  1. 一种扩大头预应力混凝土锚杆施工工法，其中，是由锚杆骨架体系与预应力混凝土灌注凝固而成的锚杆(桩)；其具体施工实施步骤是，钻孔定位；钻孔钻进至设计深度，开展旋喷或机械扩孔施工并成孔，下放锚杆的拉杆即主筋与扩大头骨架或固定直径锚头骨架；锚杆的拉杆即主筋与扩大头(变直径钢筋笼或各种囊式扩大头、以及各种扩大头等)，扩大头到位后，扩大机构将扩大头扩大至设计尺寸，然后灌注混凝土在扩大头即扩体段和非扩体段成型，至设计和规范要求的额定强度后；锚杆中拉杆即主筋采用能施加预应力的装置和方法对主筋(如带套管的无粘结预应力精轧螺纹钢筋、普通三级钢筋、钢绞线等)施加预应力；施加设计和规范要求的预应力,完成后并锁定，再撤消需要撤除的预应力施加的设备装置；锚杆的整体部分由浇筑的混凝土与锚杆骨架体构成；锚杆的整体达到额定强度后，根据工程设计和规范的要求，锚杆主筋的顶端所设置的锚固结构，与建筑物底板一并浇筑，形成抗浮抗拉或抗压体系；或依据工程设计和规范的要求，不用施加预应力与建筑物底板浇筑。
  2. 根据权利要求1所述的扩大头预应力混凝土锚杆施工工法，其中，砂石水泥三合一混凝土中，常见采用砂、细石、水泥与水搅拌成符合工程设计规范的预应力细石混凝土，细石的粒径及砼配合比例，需满足设计规范。
  3. 根据权利要求1所述的扩大头预应力混凝土锚杆施工工法，其中，亦可以在主体结构底板浇筑完成以后，在底板上开槽或预留孔槽，通过底板作为施加预应力的支点，再进行预应力混凝土锚杆桩施工工法，对钢筋施加预应力完成锚杆浇筑后，最后在开槽处浇筑混凝土完成锚杆与主体结构底板锁定；亦可以锚杆桩顶面作为施加预应力的支点，待混凝土强度达到不低于设计要求的可施加预应力的强度后，凿除泛浆找平至锚杆桩顶面施工面标高，根据设计要求实施预应力张拉锁定。
  4. 根据权利要求1所述的扩大头预应力混凝土锚杆施工工法，其中，可选择满足工程施工和设计质量要求的各种型号规格的灌注设备，用以浇筑或高压浇筑由砂、细石、水泥与水搅拌成符合工程设计规范的预应力细石混凝土，浇筑管的内径一般采用4-10cm。
  5. 根据权利要求1所述的扩大头预应力混凝土锚杆施工工法，其中，预应力抗浮抗拉锚杆钢筋，包括主筋钢筋作为基本承力的结构，主筋钢筋为精轧无粘结钢筋，主筋钢筋表面设有防腐油脂层，防腐油脂层外设有塑料薄膜套；通过涂防腐油脂层装置涂防腐油脂层，涂防腐油脂层无粘结筋通过塑料挤压机涂刷聚乙烯或聚丙烯塑料薄膜，再经冷却筒模成型塑料套管；在塑料套外采用包括混凝土或水泥砂浆、水泥浆或其他能固化材料包裹并凝结固化；预应力后施加在主筋钢筋，形成预应力锚杆杆件；将主筋钢筋，用螺母锁定，张拉钢筋施加预应力后，形成预应力锚杆杆件；预应力锚杆杆件可以是施工现场浇筑的，亦可以是工厂预制的。
  6. 根据权利要求1所述的扩大头预应力混凝土锚杆施工工法，其中，施加应用时采用如下装置：钻孔定位时在锚杆主筋上部在拉力固定端；装置包括施力机械、支架或/与支架板、钢筋夹持器或锁定螺母、支架或支架板中央设有能使锚杆的上端钢筋穿过的孔洞；锚杆钢筋的下端固定在锚杆地层或岩层的钻孔内，穿过的孔洞后上端钢筋由钢筋夹持器夹持或螺母锁定，并由施力机械施加应力，上端钢筋的通过锁定螺母或焊接等方式固定在支架板上；钢筋一般常见为精轧螺纹钢。
  7. 根据权利要求1-6之一所述的扩大头预应力混凝土锚杆施工工法，其中，钢筋采用无粘结的钢筋或有粘结的钢筋，其数量可以是一根或一根以上。
  8. 根据权利要求1-6之一所述的扩大头预应力混凝土锚杆施工工法，其中，施力机械一般有两种结构，一是使在钢筋夹持器下端向上加力的设备；另一种是在钢筋夹持器上端向上加力的设备；包括但不限于千斤顶、手动扳手、吊车、胡芦、龙门吊、轮旋盘等，电动、液压、气压机械和手动设备。
  9. 根据权利要求1-6之一所述的扩大头预应力混凝土锚杆施工工法，其中，锚杆钢筋底端具有变直径钢筋笼或普通钢筋笼骨架的扩大头锚杆，或直通非扩大头锚杆。
  10. 根据权利要求9所述的扩大头预应力混凝土锚杆施工工法，其中，可以对锚杆杆件和上部，使用包括但不限于配筋、增加截面积、增加水泥和混凝土强度与规格等方法，增加锚杆的承载强度，及对其周围的土体加固增加土体强度。
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