Construction method of prestressed anti-floating anchor rod with buckling-restraining prevention and anti-floating anchor rod

Abstract

This invention discloses a construction method for a buckling-restrained prestressed anti-buoyancy anchor and the anti-buoyancy anchor itself. The method includes: inserting a buckling-restrained precast pipe into the ground along a first direction, penetrating the upper soft soil layer and entering a lower, stronger soil layer for 1-2 meters; using the hollow cavity of the buckling-restrained precast pipe as a guide, drilling a hole in the hollow cavity and continuing drilling into the underlying soil; cleaning the drilled hole and the hollow cavity of the pipe; placing the reinforcing bar of the prestressed anchor into the drilled hole; positioning it; and pouring anchor grout to the top of the buckling-restrained precast pipe; tensioning and locking the prestressed anchor to anchor it within the foundation slab of the underground structure. This invention uses a precast outer tube to constrain the prestressed anchor rod bearing the tension force in the core, allowing the anchor rod to complete the entire tensioning and locking process without compressive buckling. The anchor head is then anchored into the base slab of the underground structure, thus completely solving the problem of compressive buckling failure of prestressed anti-buoyancy anchor rods on soft soil foundations during tensioning. During the design phase, there is no need to significantly reduce the pull-out bearing capacity of the anchor rod, thus avoiding a substantial increase in the number of anchor rods or a change to an anti-buoyancy scheme entirely composed of reinforced concrete cast-in-place piles. Therefore, it can effectively reduce the structural cost of such projects.

Description

Technical Field

[0001] This invention relates to the field of anti-buoyancy anchor construction technology, and in particular to a method for constructing an anti-buckling restrained prestressed anti-buoyancy anchor and an anti-buoyancy anchor. Background Technology

[0002] Anti-buoyancy anchors can be divided into prestressed anti-buoyancy anchors and non-prestressed anti-buoyancy anchors, depending on whether prestress is applied. They are widely used in civil engineering to improve the anti-buoyancy capacity of underground buildings or structures.

[0003] A prestressed anti-buoyancy anchor can be divided into three parts: the anchorage section, the free section, and the anchor head. The prestressed anti-buoyancy anchor applies prestress to the anchorage section through a post-tensioning construction process, and then actively reinforces the latter using the frictional force generated by the interfacial bond strength between the anchorage section and the surrounding soil and rock layers. When the groundwater head pressure adversely affects the stability and safety of underground engineering, the relative uplift between the structure and the strata is small, effectively preventing the underground structure from floating and avoiding problems such as structural cracking and water accumulation.

[0004] The main stress characteristics of prestressed anti-buoyancy anchors are that they can provide a certain pull-out bearing capacity but cannot withstand the pressure of the superstructure. Therefore, they have been generally used in underground engineering projects with relatively high groundwater levels, good geological conditions, foundations with a certain bearing capacity, and natural foundation schemes for the main structure.

[0005] In recent years, due to increasingly stringent cost control in engineering projects, prestressed anti-buoyancy anchors have begun to be used in some soft soil foundation projects. In these projects, the foundation soil has low bearing capacity and high compressibility. The weight of the superstructure is entirely borne by reinforced concrete pile foundations centrally located under vertical components such as columns and walls. The anchors are evenly and dispersedly placed on the basement floor slab between columns and walls to bear all or most of the buoyancy force from groundwater. The pile foundation bears little or no buoyancy force, resulting in significant cost savings compared to the method where all buoyancy force is borne by the pile foundations.

[0006] Conventional prestressed anti-buoyancy anchor bolts involve numerous construction steps and are difficult to control in terms of construction quality. They require the installation of penetrating sleeves in the base slab, with the anchor bolts being post-tensioned and locked after the base slab construction is completed. These sleeves, under groundwater pressure, can create potential leakage channels, significantly impacting the long-term waterproofing performance of underground engineering projects.

[0007] To mitigate the aforementioned engineering quality risks, projects often employ a structural scheme where anchor bolts are tensioned and locked before the foundation slab is constructed, followed by the installation of the foundation slab and its anchoring connection. During the tensioning stage, the tension force is typically applied to the top of the anchor bolt and gradually increases. The design locking load should be no less than 1.0 times the characteristic value of the pull-out bearing capacity required by relevant specifications.

[0008] Because the anchor rod is a slender rod and the soft soil layer above cannot provide effective lateral restraint, the top of the anchor rod is subjected to buckling and strength failure during tensioning, which can induce buoyancy failure accidents in underground engineering. Therefore, it is necessary to improve the existing technical solution. Summary of the Invention

[0009] In view of this, the purpose of this invention is to propose a method for constructing a prestressed anti-buoyancy anchor rod with anti-buckling restraint, which can solve the problem of prestressed anti-buoyancy anchor rods on soft soil foundations buckling under pressure during tensioning.

[0010] According to one aspect of the present invention, a method for constructing a buckling-restrained prestressed anti-buoyancy anchor is provided, comprising:

[0011] The buckling-restrained precast pipe is sent underground along a first direction, and the pipe penetrates the upper soft soil layer and enters the underlying layer with higher strength for 1-2m.

[0012] Guided by the hollow inner cavity of the buckling-restrained precast pipe, a hole is drilled in the hollow inner cavity and the hole is continued to be drilled in the soil below. The hole and the hollow inner cavity of the pipe are cleaned. The tendon of the prestressed anchor rod is placed into the hole, and after positioning, the anchor grout is poured to the top of the buckling-restrained precast pipe.

[0013] The prestressed anchor rod is tensioned and locked to anchor it within the base slab of the underground structure.

[0014] In the above technical solution, the precast pipe of the outer casing constrains the prestressed anchor rod bearing the tension force in the core, allowing the anchor rod to complete the entire tensioning and locking process without compressive buckling. The anchor head is then anchored into the base slab of the underground structure, thus completely solving the problem of compressive buckling failure of prestressed anti-buoyancy anchor rods on soft soil foundations during tensioning. During the design phase, there is no need to significantly reduce the pull-out bearing capacity of the anchor rod, thus avoiding a large increase in the number of anchor rods or a change to an anti-buoyancy scheme entirely composed of reinforced concrete cast-in-place piles. Therefore, the structural cost of such projects can be effectively reduced. In this embodiment, the purpose of the pipe body penetrating the upper soft soil layer and entering the underlying higher-strength stratum by 1-2m is to: prevent the pipe material from suspending in the upper soft soil layer, improve the stability of the pipe material in the stratum, and effectively prevent pipe breakage or displacement due to construction disturbance.

[0015] In some embodiments, the buckling-restrained precast pipe material includes: prestressed concrete pipe piles, circular precast vertical stiffeners, and steel pipes.

[0016] In the above technical solutions, it is recommended to adopt the circular prefabricated vertical stiffener solution because:

[0017] 1. Factory prefabrication makes construction quality easy to control; 2. Convenient to use with piling equipment, strong penetration ability, and fast construction speed; 3. Easy to connect piles and adjust the driving depth; 4. More economical than prestressed concrete pipe piles and steel pipes.

[0018] In some embodiments, the prestressed anchor is a pressure-type prestressed anchor or a tension-type prestressed anchor.

[0019] Of the above technical solutions, it is recommended to use the pressure-type prestressed anchor bolt solution because:

[0020] 1. When the anchor rod is under tension, the entire anchor section is under pressure and does not crack. It has strong corrosion resistance and is suitable for various corrosive environments. 2. Compared with tension-type prestressed anchor rods, only a free section needs to be set in the soft soil layer. It does not need to meet the structural requirement of a minimum length of not less than 4m as specified in relevant design specifications, so it is more cost-effective.

[0021] In some embodiments, the positioning specifically includes:

[0022] The buckling-restrained precast pipe and the prestressed anchor rod have their central axes coincident.

[0023] In the above technical solution, the cross-sectional centers of the buckling-restrained precast pipe and the prestressed anchor rod coincide. After construction, the buckling-restrained precast pipe surrounds the prestressed anchor rod, restraining and protecting the prestressed anchor rod from compressive buckling.

[0024] In some embodiments, the prestressed anchor rod is tensioned and locked, specifically:

[0025] After the anchor grout strength reaches the design requirements, the prestressed anchor rod is tensioned and locked. The locking load should be no less than 1.0 times the characteristic value of the pull-out bearing capacity of the prestressed anchor rod.

[0026] In the above technical solution, 1.0 times is the minimum requirement of the relevant design specifications. The advantage is that it strives to ensure that the anchor bolts will not undergo excessive additional deformation due to changes in groundwater level throughout the entire design service life of the underground structure, thus ensuring that the upward displacement of the overall structure is within a controllable range.

[0027] In some embodiments, the pad of the prestressed anchor is a circular pad, the outer ring diameter of which is 2-5 cm smaller than the diameter of the buckling restraint precast pipe, and the reinforcing bar passes directly through the inner ring opening.

[0028] In the above technical solution, the purpose of this arrangement is to facilitate a tight fit between the pad and the top of the prestressed anchor rod, so that all the tension load is transferred to the rod body of the prestressed anchor rod, ensuring that the buckling restraint precast pipe of the outer jacket does not directly bear the tension force.

[0029] In some embodiments, after positioning, the anchor grout is poured to the top of the buckling-restrained precast pipe, which further includes:

[0030] A layer of unbonded material is laid on the inner wall surface of the buckling-restrained precast pipe, and after positioning, anchor grout is poured to the top of the buckling-restrained precast pipe.

[0031] The above technical solution improves overall compressive stability. Unbonded materials provide a buffer between the anchor bolt and the pipe, further preventing the surrounding pipe from bearing tensile force, thereby improving the overall structural compressive stability.

[0032] In some embodiments, the portion of the prestressed anchor within the soft soil stratum is a free section.

[0033] In the above technical solution, the prestressed anchor rod can be designed as a free section in the soft soil layer, without considering its participation in providing pull-out resistance. This helps to reduce the prestress loss during anchor rod tensioning and avoid the upward deformation of the underground structure's bottom slab.

[0034] In some embodiments, a waterproof layer is provided at the contact surface between the prestressed anchor rod and the bottom slab of the underground structure above the soft soil layer.

[0035] In the above technical solution, a waterproof layer is set at the top of the prestressed anchor rod, and the bottom of the underground structure slab is tightly attached to the waterproof layer to prevent groundwater from seeping in and enhance the waterproof effect.

[0036] In some embodiments, the material of the reinforcing bars of the prestressed anchor rod includes: PSB precision rolled threaded steel and prestressed steel strand.

[0037] In the above technical solution, the ribs have high strength and are easy to tension, which helps to save materials and reduce costs.

[0038] According to another aspect of the present invention, a buckling-restrained prestressed anti-buoyancy anchor is provided, which is applied to the above-mentioned buckling-restrained prestressed anti-buoyancy anchor construction method. The anti-buoyancy anchor includes a buckling-restrained precast tube and a prestressed anchor disposed in the hollow cavity of the buckling-restrained precast tube.

[0039] In the above technical solution, the precast pipe of the outer casing constrains the prestressed anchor rod bearing the tension force in the core, allowing the anchor rod to complete the entire tensioning and locking process without compressive buckling. The anchor head is then anchored into the base slab of the underground structure, thus completely solving the problem of compressive buckling failure of prestressed anti-buoyancy anchor rods on soft soil foundations during tensioning. During the design phase, there is no need to significantly reduce the pull-out bearing capacity of the anchor rods, thus avoiding a substantial increase in the number of anchor rods or a change to an anti-buoyancy scheme entirely composed of reinforced concrete cast-in-place piles. Therefore, it can effectively reduce the structural cost of such projects. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a flowchart illustrating an embodiment of the construction method for a buckling-resistant prestressed anti-buoyancy anchor bolt according to the present invention.

[0042] Figure 2 This is a structural schematic diagram of an embodiment of the anti-buckling restraint prestressed anti-buoyancy anchor bolt construction method of the present invention. Detailed Implementation

[0043] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be particularly noted that the following embodiments are for illustrative purposes only and do not limit the scope of the invention. Similarly, the following embodiments are only some, not all, embodiments of the present invention, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] This invention provides a method for constructing a prestressed anti-buoyancy anchor bolt with buckling resistance and an anti-buoyancy anchor bolt, which can solve the problem of buckling under pressure during the tensioning process of prestressed anti-buoyancy anchor bolts on soft soil foundations.

[0045] Example 1

[0046] Please see Figure 1 , Figure 2 A method for constructing a buckling-restrained prestressed anti-buoyancy anchor bolt, comprising:

[0047] S101. The buckling-restrained precast pipe 10 is sent into the ground along a first direction, and the pipe body penetrates the upper soft soil layer 60 and enters the underlying layer with higher strength for 1-2m.

[0048] S102. Using the hollow inner cavity of the buckling-restrained precast pipe 60 as a guide, drill a hole in the hollow inner cavity and continue drilling in the soil below. Clean the hole and the hollow inner cavity of the pipe 60. Place the reinforcing bar 21 of the prestressed anchor rod 20 into the hole. After positioning, pour the anchor grout to the top of the buckling-restrained precast pipe 60.

[0049] S103. Tension and lock the prestressed anchor rod 20 to anchor the prestressed anchor rod 20 in the underground structure base plate 40.

[0050] In this embodiment, the first direction is perpendicular to the ground. This embodiment of the invention is applicable to basements, and all anti-buoyancy measures for basements are vertical.

[0051] In this embodiment, the prestressed anchor rod bearing the tension force in the core is constrained by the precast pipe of the outer casing, allowing the anchor rod to complete the entire tensioning and locking process without compressive buckling. The anchor head is then anchored into the base slab of the underground structure, thus completely solving the problem of compressive buckling failure of prestressed anti-buoyancy anchor rods on soft soil foundations during tensioning. During the design phase, there is no need to significantly reduce the pull-out bearing capacity of the anchor rod, thus avoiding a substantial increase in the number of anchor rods or a change to an anti-buoyancy scheme entirely composed of reinforced concrete cast-in-place piles. Therefore, the structural cost of such projects can be effectively reduced.

[0052] In this embodiment, the buckling-restrained precast pipe 10 includes: a prestressed concrete pipe pile, a circular precast vertical stiffener, and a steel pipe. In this embodiment, a circular precast vertical stiffener is recommended because:

[0053] 1. Factory prefabrication makes construction quality easy to control;

[0054] 2. It is easy to use with piling equipment, has strong penetration ability, and fast construction speed;

[0055] 3. Convenient pile splicing and easy adjustment of driving depth; 4. More economical than prestressed concrete pipe piles and steel pipes.

[0056] In this embodiment, the prestressed anchor 20 is a compression type prestressed anchor or a tension type prestressed anchor. In this embodiment, a compression type prestressed anchor is recommended because:

[0057] 1. When the anchor bolt is subjected to tensile force, the entire anchoring section is under pressure without cracking, and it has strong corrosion resistance, making it suitable for various corrosive environments;

[0058] 2. Compared with tension-type prestressed anchors, only a free section needs to be set in the soft soil layer. It does not need to meet the structural requirement that the minimum length of the free section is not less than 4m as specified in relevant design codes, so it has a cost advantage.

[0059] In this embodiment, the positioning specifically means that the central axes of the buckling-restrained precast pipe 10 and the prestressed anchor 20 coincide. The cross-sectional centers of the buckling-restrained precast pipe 10 and the prestressed anchor 20 also coincide. After construction, the buckling-restrained precast pipe surrounds the prestressed anchor, restraining and protecting it from compressive buckling.

[0060] In this embodiment, the prestressed anchor rod 20 is tensioned and locked. Specifically, after the anchor grout strength reaches the design requirements, the prestressed anchor rod 20 is tensioned and locked. The locking load should be no less than 1.0 times the characteristic value of the pull-out bearing capacity of the prestressed anchor rod. 1.0 times is the minimum limit requirement of relevant design specifications. The advantage is that it strives to ensure that the anchor rod will not undergo excessive additional deformation due to changes in groundwater level throughout the entire design service life of the underground structure, thus ensuring that the upward displacement of the overall structure is within a controllable range.

[0061] In this embodiment, the pad of the prestressed anchor 20 is a circular pad 31. The outer diameter of the pad 31 is 2-5 cm smaller than the diameter of the buckling-restrained precast tube 20, and the reinforcing bar 21 passes directly through the inner ring opening. The purpose of this arrangement is to facilitate a tight fit between the pad 31 and the top of the prestressed anchor 20, transferring all the tension load to the rod body of the prestressed anchor 20, and ensuring that the buckling-restrained precast tube 10 does not directly bear the tension force.

[0062] In this embodiment, after positioning, the anchor grout is poured to the top of the buckling-restrained precast pipe 10, and the process further includes: laying a layer of unbonded material 50 on the inner wall surface of the buckling-restrained precast pipe 10, and then pouring anchor grout to the top of the buckling-restrained precast pipe 10 after positioning. The unbonded material 50 can improve the overall compressive stability. The unbonded material provides a buffering effect between the anchor and the pipe, further preventing the surrounding pipe from bearing tensile force, thereby improving the compressive stability of the overall structure.

[0063] In this embodiment, the portion of the prestressed anchor 20 within the soft soil stratum is a free section. Designing the prestressed anchor as a free section within the soft soil stratum, without considering its role in providing pull-out resistance, helps reduce prestress loss during anchor tensioning and avoids upward deformation of the underground structure's base slab.

[0064] In this embodiment, a waterproof layer is provided at the contact surface between the prestressed anchor rod 20 and the underground structure base plate above the soft soil layer. The waterproof layer is provided at the top of the prestressed anchor rod, and the bottom end of the underground structure base plate is in close contact with the waterproof layer to prevent groundwater from seeping in and enhance the waterproof effect.

[0065] In this embodiment, the material of the reinforcing bars 21 of the prestressed anchor rod 20 includes: PSB precision-rolled threaded steel and prestressed steel strand. The reinforcing bars have high strength and are easy to tension, which helps save materials and reduce costs.

[0066] To better understand this embodiment, a specific example will be used for explanation below.

[0067] 1) Please refer to Figure 2Construction of buckling-restrained precast pipe 10: The lower end of buckling-restrained precast pipe 10 does not need to be sealed. The buckling-restrained precast pipe 10 is vertically sent into the ground by the equipment to ensure that the pipe body penetrates the upper soft soil layer 60 and enters the underlying layer with better soil quality and higher strength by 1-2m. The area above the dividing line in the figure is the soft soil layer, and the area below is the underlying layer with higher strength.

[0068] 2) Construction of prestressed anchor rod 20: Guided by the hollow inner cavity of buckling-restrained precast pipe 10, the drill bit and drill rod of the anchor rod drilling machine drill vertically through the hollow inner cavity and continue drilling into the soil below. The borehole and the hollow inner cavity of the pipe 10 are cleaned. The reinforcing bar 21 of the prestressed anchor rod 20 is placed into the borehole. After accurate positioning, the anchor grout is poured to the top of the buckling-restrained precast pipe 10.

[0069] 3) Tensioning and locking the prestressed anchor rod 20: An anchor head 30 is installed at the top of the prestressed anchor rod. The anchor head 30 includes a circular pad 31 and an anchoring device 32. After the strength of the prestressed anchor rod 20 reaches the design requirements, the prestressed anchor rod 20 is then tensioned and locked. The locking load should not be less than 1.0 times the characteristic value of the pull-out bearing capacity of the anchor rod.

[0070] 4) Anchor the anchor head 30 to the underground structure base plate 40: The anchoring device 32 is located above the annular pad 31. After the prestressed anchor rod 20 is locked, the construction of the underground structure base plate 40 is carried out, and the anchoring device 32 is anchored in the base plate 40.

[0071] The above-mentioned method for constructing a buckling-restrained prestressed anti-buoyancy anchor rod involves first inserting a precast outer casing 10 to restrain the subsequently constructed core prestressed anchor rod 20, which bears the tension force. This allows the anchor rod to complete the entire tensioning and locking process without buckling under pressure. Then, the anchor head 30 is anchored within the base slab 40 of the underground structure, thereby completely solving the problem of buckling failure of the prestressed anti-buoyancy anchor rod 20 on soft soil foundations during the tensioning process.

[0072] First, the buckling-restrained precast pipe 10 can be selected from precast prestressed concrete pipe piles, circular precast vertical stiffeners, or steel pipes, which facilitates construction procurement and saves project costs. The diameter and wall thickness of the pipe 10 should be selected according to design calculations to ensure that the buckling-restrained precast pipe 10 has sufficient strength to prevent the core prestressed anchor 20 from buckling failure.

[0073] Furthermore, the prestressed anchor 20 can be either a compression type or a tension type prestressed anchor to meet different design and construction requirements. The diameter and length of the anchor in the anchoring section are determined through design calculations to ensure that the prestressed anchor 20 provides sufficient pull-out resistance; the diameter of the anchor in the free section is determined through design calculations to ensure sufficient compressive strength within the section.

[0074] Simultaneously, the cross-sectional centers of the buckling-restrained precast pipe 10 and the prestressed anchor 20 coincide. After construction, the buckling-restrained precast pipe 10 surrounds the prestressed anchor 20, restraining and protecting the prestressed anchor 20 from compressive buckling. This alleviates local stress concentration caused by eccentric compression of the prestressed anchor 20 and enhances the restraining effect of the buckling-restrained precast pipe 10.

[0075] In addition, the reinforcement of the prestressed anchor rod 20 is made of PSB precision-rolled threaded steel or prestressed steel strand. The reinforcement has high strength and is easy to tension, which helps to save materials and costs, and is convenient to meet construction requirements. The lower end face of the annular pad 31 is a complete annular pad. The outer ring diameter of the pad is 2-5 cm smaller than the diameter of the prestressed anchor rod 20. The reinforcement 21 passes directly through the inner ring opening, which facilitates the tight fit between the pad and the top of the prestressed anchor rod 20. This transfers all the tension load to the rod body of the prestressed anchor rod 20, ensuring that the buckling restraint precast pipe 10 does not directly bear the tension force, thus achieving the function of preventing buckling.

[0076] Furthermore, an unbonded material 50 can be optionally inserted between the buckling-restrained precast pipe 10 and the prestressed anchor 20 to further improve the overall compressive stability. The prestressed anchor 20 can be designed as a free section within the soft soil layer 60, without being considered for providing pull-out resistance, which helps reduce prestress loss during anchor tensioning and avoids upward deformation of the underground structure base slab 40. A waterproof layer is installed at the top of the prestressed anchor 20, and the bottom of the underground structure base slab 40 is tightly fitted with the waterproof layer to prevent groundwater infiltration and enhance the waterproofing effect.

[0077] Finally, the present invention provides a method for constructing a buckling-restrained prestressed anti-buoyancy anchor rod. The precast outer tube restrains the prestressed anchor rod bearing the tension force in the core, allowing the anchor rod to complete the entire tensioning and locking process without buckling under pressure. The anchor head is then anchored into the base slab of the underground structure, thus completely solving the problem of buckling failure of prestressed anti-buoyancy anchor rods on soft soil foundations during tensioning. During the design phase, there is no need to significantly reduce the pull-out bearing capacity of the anchor rod, thereby avoiding a substantial increase in the number of anchor rods or a change to an anti-buoyancy scheme entirely composed of reinforced concrete cast-in-place piles. Therefore, it can effectively reduce the structural cost of such projects.

[0078] Example 2

[0079] Please see Figure 2 A buckling-restrained prestressed anti-buoyancy anchor rod is disclosed, applied to the buckling-restrained prestressed anti-buoyancy anchor rod construction method described in one embodiment. The anti-buoyancy anchor rod includes a buckling-restrained precast tube 10 and a prestressed anchor rod 20 disposed within the hollow cavity of the buckling-restrained precast tube. The specific working principle and installation method have been detailed in one embodiment and will not be repeated here.

[0080] In this embodiment, the prestressed anchor rod bearing the tension force in the core is constrained by the precast pipe of the outer casing, allowing the anchor rod to complete the entire tensioning and locking process without compressive buckling. The anchor head is then anchored into the base slab of the underground structure, thus completely solving the problem of compressive buckling failure of prestressed anti-buoyancy anchor rods on soft soil foundations during tensioning. During the design phase, there is no need to significantly reduce the pull-out bearing capacity of the anchor rod, thus avoiding a substantial increase in the number of anchor rods or a change to an anti-buoyancy scheme entirely composed of reinforced concrete cast-in-place piles. Therefore, the structural cost of such projects can be effectively reduced.

[0081] The above description is only a part of the embodiments of the present invention and does not limit the scope of protection of the present invention. Any equivalent device or equivalent process transformation made based on the content of the present invention specification and drawings, or direct or indirect application in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for constructing a buckling-restrained prestressed anti-buoyancy anchor, characterized in that, include: The buckling-restrained precast pipe is sent underground along a first direction, and the pipe penetrates the upper soft soil layer and enters the underlying layer with higher strength for 1-2m. Guided by the hollow inner cavity of the buckling-restrained precast pipe, a hole is drilled in the hollow inner cavity and the hole is continued to be drilled in the soil below. The hole and the hollow inner cavity of the pipe are cleaned. The tendon of the prestressed anchor rod is placed into the hole, and after positioning, the anchor grout is poured to the top of the buckling-restrained precast pipe. The prestressed anchor rod is tensioned and locked to anchor it within the base slab of the underground structure. The prestressed anchor plate is a circular ring plate, and the outer ring diameter of the plate is 2-5 cm smaller than the inner diameter of the buckling restraint precast pipe. The reinforcement passes directly through the inner ring opening. After positioning, the anchor grout is poured up to the top of the buckling-restrained precast pipe, which also includes: A layer of unbonded material is laid on the inner wall surface of the buckling-restrained precast pipe, and after positioning, anchor grout is poured to the top of the buckling-restrained precast pipe.

2. The construction method of the anti-buckling restrained prestressed anti-buoyancy anchor bolt as described in claim 1, characterized in that, The buckling-restrained precast pipe material includes: prestressed concrete pipe piles, circular precast vertical stiffeners, and steel pipes.

3. The construction method for a buckling-resistant, prestressed, anti-buoyancy anchor bolt as described in claim 1, characterized in that, The prestressed anchor bolt is either a pressure-type prestressed anchor bolt or a tension-type prestressed anchor bolt.

4. The construction method of the anti-buckling restrained prestressed anti-buoyancy anchor bolt as described in claim 1, characterized in that, The location is specifically: The buckling-restrained precast pipe and the prestressed anchor rod have their central axes coincident.

5. The construction method of the anti-buckling restrained prestressed anti-buoyancy anchor bolt as described in claim 1, characterized in that, The prestressed anchor rod is tensioned and locked, specifically: After the anchor grout strength reaches the design requirements, the prestressed anchor rod is tensioned and locked. The locking load should be no less than 1.0 times the characteristic value of the pull-out bearing capacity of the prestressed anchor rod.

6. The construction method of the anti-buckling restrained prestressed anti-buoyancy anchor bolt as described in claim 1, characterized in that, The portion of the prestressed anchor rod within the soft soil stratum is a free section.

7. The construction method of the anti-buckling restrained prestressed anti-buoyancy anchor bolt as described in claim 1, characterized in that, A waterproof layer is provided at the contact surface between the prestressed anchor rod and the bottom slab of the underground structure above the soft soil layer.

8. A prestressed anti-buoyancy anchor bolt with buckling restraint, characterized in that, The method for constructing a buckling-restrained prestressed anti-buoyancy anchor bolt according to any one of claims 1-7, wherein the anti-buoyancy anchor bolt comprises a buckling-restrained precast tube and a prestressed anchor bolt disposed in the hollow cavity of the buckling-restrained precast tube.

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