WO2023273253A1 - 可回收锚入式预应力吊脚桩支护结构及施工方法 - Google Patents

可回收锚入式预应力吊脚桩支护结构及施工方法 Download PDF

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Publication number
WO2023273253A1
WO2023273253A1 PCT/CN2021/141916 CN2021141916W WO2023273253A1 WO 2023273253 A1 WO2023273253 A1 WO 2023273253A1 CN 2021141916 W CN2021141916 W CN 2021141916W WO 2023273253 A1 WO2023273253 A1 WO 2023273253A1
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Prior art keywords
anchor
wedge
pile
shaped
soil
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PCT/CN2021/141916
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English (en)
French (fr)
Inventor
任晓光
杨志银
张兴杰
王召磊
蒋毅
闫贵海
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中冶建筑研究总院（深圳）有限公司
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Publication of WO2023273253A1 publication Critical patent/WO2023273253A1/zh

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    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D17/00—Excavations; Bordering of excavations; Making embankments
    • E02D17/02—Foundation pits
    • E02D17/04—Bordering surfacing or stiffening the sides of foundation pits
    • 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
    • E02D5/22—Piles
    • E02D5/34—Concrete or concrete-like piles cast in position ; Apparatus for making same
    • 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
    • E02D5/76—Anchorings for bulkheads or sections thereof in as much as specially adapted therefor
    • E02D5/765—Anchorings for bulkheads or sections thereof in as much as specially adapted therefor removable

Definitions

  • the present application relates to the technical field of foundation pit support, for example, to a retrievable anchored prestressed pile support structure and a construction method.
  • foundation pits with soil on the upper part and rock on the lower part of the excavation surface, that is, soil-rock combination foundation pits.
  • the commonly used support forms for this type of foundation pit include hanging piles, composite soil nail walls and conventional support piles.
  • the hanging piles generally use hanging piles + trapezoidal rock shoulder protection feet + anchor bolt locking feet.
  • the width of the rock shoulder and the quality of the locking foot anchor determine the success or failure of the support structure, and the safety degree is low; It is difficult to control the width of the rock abutment during the process.
  • the width of the rock abutment is limited, so the support depth is limited, and the bottom of the pile needs to be embedded in the rock abutment to a certain depth, and the progress of hole drilling is slow and the cost is high.
  • Composite soil nail wall structure generally adopts micro-pile + soil nail + anchor rod, which is only suitable for foundation pits with simple surrounding environment and shallow excavation depth; conventional support piles need to embed the bottom of the pile to a certain depth in the bottom of the pit. Higher foundation pit, high cost and long construction period.
  • the support structure commonly used in the above foundation pits is a temporary structure, and it will be put into service after the completion of the underground structure and left underground with the backfill of the foundation pit, resulting in a large waste of steel.
  • the embodiment of the present application discloses a recyclable anchored prestressed suspension foot pile support structure and a construction method.
  • the embodiment of the present application discloses a recyclable anchored prestressed stilt pile support structure, which is installed in a soil-rock composite foundation pit.
  • the recyclable anchored prestressed stilt pile support structure includes:
  • the hanging pile is arranged on the air side of the soil, and the bottom end of the hanging pile is arranged on the rock mass;
  • the plurality of anchor rods are divided into two groups, the first group of anchor rods in the two groups of anchor rods are vertically arranged in the suspension foot piles and penetrate downwards.
  • the second set of anchor rods in the two groups of anchor rods is obliquely penetrated through the suspension foot pile and the soil body, and/or obliquely penetrates the suspension foot pile and the rock body;
  • Each anchor rod in the plurality of anchor rods includes an anchor bar and an anchor component, the anchor component is arranged at the bottom end of the anchor bar and is located in the soil or the rock body, and the anchor component and The anchor bars are detachably connected.
  • the embodiment of the present application also discloses a construction method of a recoverable anchored prestressed stilt pile support structure, which includes the following steps:
  • Fig. 1 is a schematic diagram of the arrangement of a recyclable anchored prestressed sling pile support structure in the foundation pit according to the embodiment of the present application;
  • Fig. 2 is a structural schematic diagram of an anchor rod in a retrievable anchored prestressed stilt pile support structure according to an embodiment of the present application
  • Fig. 3 is a schematic diagram of the top fixing structure of the anchor rod in a retrievable anchored prestressed sling pile support structure according to an embodiment of the present application;
  • Fig. 4 is A-A sectional schematic diagram among Fig. 2;
  • Fig. 5 is B-B sectional schematic diagram among Fig. 2;
  • Fig. 6 is a structural schematic diagram of an isolation bracket in a recoverable anchored prestressed stilt pile support structure according to an embodiment of the present application
  • Fig. 7 is a schematic cross-sectional view of C-C in Fig. 1 .
  • Anchor rod 21. Anchor tendon; 22. Anchor component; 221. Bearing platform; 222. Wedge-shaped pressing piece; 223. Wedge-shaped thimble; 224. Thimble sleeve; 225. Covering; 226. Temporary fixing sheet; 227. Temporary screw; 23. Locking component; 231. Backing plate; 232. Lock nut; 24. Isolation bracket; 241. Center through hole; 242. Grouting pipe hole; 25. Grouting pipe; 26. Grouting body; 27. Isolation sleeve.
  • connection should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integrated ; It can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediary, and it can be the internal communication of two components or the interaction relationship between two components.
  • connection can be a fixed connection, a detachable connection, or an integrated ; It can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediary, and it can be the internal communication of two components or the interaction relationship between two components.
  • a first feature being "on” or “under” a second feature may include direct contact between the first and second features, and may also include the first and second features Not in direct contact but through another characteristic contact between them.
  • “above”, “above” and “above” the first feature on the second feature include that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature.
  • “Below”, “beneath” and “under” the first feature to the second feature include that the first feature is directly below and obliquely below the second feature, or simply means that the first feature has a lower level than the second feature.
  • the embodiment of the present application firstly provides a recyclable anchored prestressed stilt pile support structure, aiming at the problems of steel waste and complicated construction in the earth-rock composite foundation pit support structure used in the related technology, which is complicated for the surrounding environment.
  • the soil-rock composite foundation pit with deep depth and large excavation area provides a support structure of hanging piles that avoids steel waste, reduces costs, and is easy to construct.
  • the rock mass 200 is below the soil mass 100
  • the recyclable anchored prestressed stilt pile support structure includes a stilt pile 1 and an anchor rod 2, and the stilt pile 1 is arranged on the air side of the soil body 100 in the foundation pit, The bottom end of the hanging pile 1 is arranged on the rock mass 200; there are multiple anchor rods 2, and the plurality of anchor rods 2 are divided into two groups.
  • the first group of anchor rods 2 is vertically arranged in the hanging pile 1 and downward Penetrating in the rock mass 200, the second group of anchor rods 2 obliquely penetrate the hanging pile 1 and the soil 100, and/or obliquely penetrate the hanging pile 1 and the rock mass 200; wherein, the anchor rod 2 includes an anchor The tendon 21 and the anchoring component 22, the anchoring component 22 is arranged at the bottom of the anchoring tendon 21 and is located in the soil mass 100 or the rock mass 200, and the anchoring component 22 and the anchoring tendon 21 are detachably connected.
  • the hanging pile 1 is set on the rock mass 200 without entering the rock mass 200, and the anchor rod 2 is set in the hanging pile 1 and penetrates downward through the rock mass 200 to form a pair of hanging feet.
  • the fixing of the pile 1, the anchor rod 2 and the hanging foot pile 1 are fixed as a whole, which not only ensures the stability of the overall structure, but also reduces the cost of the hanging foot pile 1 entering the rock, and the construction is simple.
  • the anchor bar 21 is set into two groups of vertical and oblique, and the hanging pile 1 and the soil 100, as well as the hanging pile 1 and the rock mass 200 are respectively pierced.
  • the prestressing can effectively control the deformation of the foundation pit, improve the fixing strength between the hanging pile 1 and the soil 100 and between the hanging pile 1 and the rock mass 200, the supporting structure is stable and reliable, and the construction is convenient.
  • the detachable anchor component 22 at the bottom of the anchor bar 21, it is convenient to recover the anchor bar 21 after the construction, so as to realize the recycling of the anchor bar 2 for reuse, which not only reduces the cost, but also reduces the pollution to the surrounding environment.
  • the first group of anchor rods 2 and the second group of anchor rods 2 have the same structure, but the anchoring angles are different, and the distance between multiple anchor rods 2 is set according to actual calculation.
  • the bottom end of the first group of anchor rods 2 pierced in the rock mass 200 can be lower than the bottom end of the rock shoulder 500 to achieve a better anchoring effect.
  • the oblique direction of the second group of anchor rods 2 in the soil mass 100 The anchoring angle is 15°-35° (for example, the oblique anchoring angle can be the reference datum line in the horizontal direction in Fig. 1), and the oblique anchoring angle in the rock mass 200 is 10°-15°.
  • the length of the anchor rod 2 is determined according to the load calculation.
  • the second group of anchor rods 2 is arranged obliquely.
  • the oblique direction can be any direction between the vertical direction and the horizontal direction, or any direction other than the vertical direction.
  • the anchor assembly 22 includes a bearing platform 221, a wedge-shaped pressing piece 222, a wedge-shaped thimble 223, a thimble sleeve 224 and a cover 225, wherein,
  • the supporting platform 221 is provided with a central through hole, and the central through hole is a circular platform hole; the diameter of the top hole of the circular platform hole is smaller than that of the bottom hole.
  • the round platform formed by the combination of two wedge-shaped pressing pieces 222 can be installed in the central through hole of the carrying platform 221 and form an integral body with it.
  • the sheet 226 and the temporary screw 227, the temporary fixing sheet 226 covers the seam and is fixed on the bearing platform 221 by the temporary screw 227, so as to realize the integration of the two.
  • the temporary fixing piece 226 is made of plastic material or other materials that are easy to be cut and broken.
  • wedge-shaped thimbles 223, at least two wedge-shaped thimbles 223 are arranged on the end surface of the bottom end of the anchor bar 21, and at least two wedge-shaped slideways 211 are arranged at the bottom end of the anchor bar 21, and the wedge-shaped thimbles 223 correspond to the wedge-shaped slideways 211 Set, the wedge-shaped thimble 223 can slide into the wedge-shaped slideway 211 so that the wedge-shaped pressing piece 222 is separated from the anchor bar 21; as shown in Figure 5, there are three wedge-shaped thimbles 223, which are the same as the three wedge-shaped slideways on the anchor bar 21 shown in Figure 4 211 is set correspondingly.
  • the wedge-shaped thimble 223 can slide into the wedge-shaped slideway 211 and spread the two wedge-shaped pressing pieces 222, so that the wedge-shaped pressing piece 222 is separated from the anchor bar 21, which is convenient for the anchor bar 21's recovery. It can be understood that the dimensions of the wedge-shaped thimble 223 , the wedge-shaped slideway 211 and the wedge-shaped pressing piece 222 should be designed and calculated in advance to meet the above-mentioned recovery requirements.
  • the thimble sleeve 224 is sleeved on the outside of at least two wedge-shaped thimbles 223; with reference to FIG. 2 and FIG.
  • the movement of the anchor tendons 21 and the movement of the anchor tendons 21 are axially limited.
  • the thimble sleeve 224 is sleeved on the outer circumference of the three wedge-shaped thimbles 223 to define the positions of the three wedge-shaped thimbles 223.
  • the thimble sleeve 224 can define the circumferential direction of the wedge-shaped thimble 223. The displacement is to ensure the vertical sliding of the anchor bar 21, and ensure that the wedge-shaped pressing piece 222 is separated from the anchor bar 21 smoothly.
  • the cover 225 covers the wedge-shaped thimble 223 and the thimble sleeve 224 and is fixed on the supporting platform 221 , the thimble sleeve 24 and the wedge-shaped thimble 223 are fixedly connected with the cover 225 .
  • the cover 225 adopts a groove structure with an upward opening, and the opening can cover the wedge-shaped thimble 223 and the thimble sleeve 224 and then be fixed on the bottom surface of the bearing platform 221, so as to seal the wedge-shaped thimble 223 and the thimble sleeve 224, At the same time, the wedge-shaped thimble 223 and the thimble sleeve 224 are fixed on the inner side wall of the bottom end of the cover 225, so as to realize fixing the bottom end of the anchor rod 2 .
  • the fixing methods involved in the embodiments of the present application are all welding and fixing, and the metal parts used, such as steel bars, are all welded and fixed.
  • the anchor rod 2 further includes a locking assembly 23, the locking assembly 23 includes a backing plate 231 and a locking nut 232, and the top end of the anchor bar 21 passes through the suspension pile 1 and the backing plate 231 and is locked with the locking nut 232 to Anchor bar 21 is fixed and tensioned.
  • the top of the anchor bar 21 is successively pierced with the hanging pile 1 and the crown beam 300, the backing plate 231 is arranged on the top of the crown beam 300, and the top of the anchor bar 21 is pierced with a pad
  • the plate 231 is also connected with the lock nut 232, which can provide tension prestress for the anchor rod 2, and is convenient for fixing and pouring.
  • a hydraulic jack is used to apply a pulling force to the anchor bar 21, so that the lock nut 232 is separated from the backing plate 231, and then the lock nut 232 is removed to facilitate pulling out the anchor bar 21 later.
  • the top ends of the anchor tendons 21 are fixed on the outer wall of the suspension foot pile 1 through the locking assembly 23 .
  • the anchor rod 2 further includes an isolation bracket 24, and there are multiple isolation brackets 24, and the plurality of isolation brackets 24 are arranged at intervals along the long axis direction of the anchor tendon 21 (for example, refer to the long axis direction L1 in FIG. 2 ). , the anchor bar 21 is set on the spacer bracket 24 to limit the position.
  • the anchor rod 2 further includes a grouting pipe 25 , and the grouting pipe 25 is passed through the spacer bracket 24 to limit the position.
  • the spacer bracket 24 is a flat piece, and the spacer bracket 24 is provided with a central through hole 241 and a grouting pipe hole 242.
  • the grouting pipe 25 includes a The grout pipe and the normal pressure grout pipe, the anchor bar 21 is penetrated in the central through hole 241, the grout pipe 25 is penetrated in a plurality of grout pipe holes 242, and the multi-channel spacer bracket 24 (that is, multiple Road spacer bracket 24 is arranged at intervals along anchor bar 21), can maintain the verticality of anchor bar 21 and grouting pipe 25, guarantees that anchor bar 21 pulls out and reclaims smoothly.
  • the grout is first injected through the normal pressure grouting pipe until the hole overflows, and the second grouting is carried out through the high pressure grouting pipe within 2 hours after the final setting of the cement grout, and the pressure is not less than 2MPa to form the grouting body 26.
  • the suspension foot pile 1 includes a longitudinal bar 11, a stirrup 12 and a support bar 13, a plurality of stirrups 12 are arranged at intervals in the direction of the long axis of the longitudinal bar 11, and a plurality of longitudinal bars 11 are attached to the sides of the stirrup 12.
  • the inner side walls are arranged at intervals, and the two ends of the support bars 13 are respectively connected to the inner side walls of the stirrups 12 to divide the plane where the stirrups 12 is located into an arched area adjacent to the soil and an arched area adjacent to the sky, and the anchor bars 21 are arranged in the arched area adjacent to the soil.
  • one support bar 13 may be connected to each stirrup 12 .
  • one support bar 13 can be connected to one stirrup 12 in every two stirrups 12, for example, if the spacing distance between each stirrup 12 is u, then every 2u spacing distance can be Set a support bar 13. But it is not limited to the arrangement of such support bars 13 .
  • the stirrup 12 is circular, and the two ends of the support reinforcement 13 are connected in the stirrup 12 to divide the ring into two areas, adjacent to the soil arch area (Fig. 7 middle upper area) and the empty arch area (lower area in Fig. 7), for example, the height of support reinforcement 13 is a quarter circle diameter length, is convenient to set anchor bar 21 to improve anchorage strength on the side of soil.
  • the longitudinal bars 11, stirrups 12 and support bars 13 are welded and fixed to each other to form a reinforcement cage, which is convenient to fall on the top of the rock mass 200 for casting.
  • the arc segment of the anchor bar 21 in the arch area adjacent to the soil abuts against the inner wall of the stirrup 12 and is arranged alternately with the longitudinal bars 11, and the straight line segment of the anchor bar 21 in the arch area adjacent to the soil abuts on the support steel bar 13 interval settings.
  • the arch area adjacent to soil is a semicircle area adjacent to soil
  • the arch area adjacent to air is a semicircle area adjacent to air.
  • the anchor bar 21 is set against the inner wall of the stirrup 12 and the inner wall of the support bar 13, forming a semicircular radial layout and a straight line layout respectively.
  • the anchor bar group, the specific number of anchor bar 21 is determined according to the load calculation.
  • the anchor bars 21 are evenly spaced, and the longitudinal bars 11 are evenly spaced.
  • seven anchor bars 21 are arranged on the inner wall of the stirrup 12, and three anchor bars 21 are arranged on the inner side of the support bar 13, and the length of each anchor bar 21 is The depth of anchoring into the rock body in the direction is greater than or equal to 6m to provide sufficient anchoring strength.
  • the anchor rod 2 further includes a spacer sleeve 27 , the spacer sleeve 27 is sleeved on the anchor bar 21 , and the bottom end of the spacer sleeve 27 stops against the top of the bearing platform 221 .
  • the isolation sleeve 27 is sleeved on the outside of the anchor bar 21 for isolating the anchor bar 21 and the grouting body 26 , so as to facilitate the extraction and recovery of the anchor bar 21 at a later stage.
  • Isolation sleeve 27 adopts plastic bellows or metal bellows.
  • antirust agent and butter can be painted on the outside of anchor bar 21 to ensure sufficient lubricity and facilitate the recovery of anchor bar 21.
  • a retrievable anchored prestressed stilt pile support structure in the embodiment of the present application is described below through an embodiment.
  • the first set of anchors 2 are recyclable prestressed anchors for the pile body, and the second set of anchors 2 are soil (rock)
  • the body can recover prestressed anchor rods, and the two groups of anchor rods 2 have the same structure.
  • the anchor bar 21 is made of prestressed rebar, the bottom end is threaded and chamfered at the bottom end with 2 mm, the length of the thread is the thickness of the carrier 221 + 10 mm, the strength and diameter are determined according to the load calculation; the isolation sleeve 27 Plastic bellows or metal bellows can be used.
  • the grouting body 26 is formed by grouting pure cement slurry.
  • the carrier body 221 is a cylinder made of Q345 steel with a thickness of not less than 50mm and a diameter slightly smaller than the diameter of the drilled hole.
  • the center of the cylinder is round.
  • the diameter of the upper bottom of the trapezoidal hole and the circular truncated hole is the diameter of the anchor bar 21 + 10mm, and the diameter of the lower bottom is the diameter of the upper bottom + the thickness of the carrier 221 ⁇ tan25° ⁇ 2;
  • the wedge-shaped clip 222 is made of Q345 steel, and the inner sleeve and the anchor bar 11 Bottom thread set, two wedge-shaped clips 222 form a hollow circular table, which can be threadedly connected with the bottom of the anchor bar 21, and the outer size of the circular table is slightly smaller than the size of the circular table hole in the middle of the carrier 221;
  • the wedge-shaped slideway 211 is at the bottom of the anchor bar 21 After threading, planing and milling is formed (the deepest depth of the wedge-shaped slideway
  • the normal-pressure grouting pipe adopts a PE plastic pipe (outer diameter 25mm, the pressure is greater than or equal to 1MPa, and the bottom end is open), and the high-pressure grouting pipe adopts a PE plastic pipe ( The outer diameter is 25mm, the pressure is greater than or equal to 4MPa, the bottom end is sealed, the diameter of the pipe body is 5mm, the circumference is greater than or equal to 5, and the axial distance is less than or equal to 15cm).
  • the number of anchor bars 21 is determined according to the load calculation and is greater than or equal to 7;
  • the linear layout in the area is greater than or equal to 3; the anchor rods are 2 long.
  • the degree of anchoring into the rock mass at the bottom of the pit is greater than or equal to 6m.
  • the longitudinal bar 11 is made of hot-rolled ribbed steel bar (strength and diameter are determined according to the calculation of the load)
  • the spiral stirrup 12 is made of hot-rolled smooth round steel bar (the strength and diameter are determined according to the calculation of the load)
  • the concrete Commercial concrete is used (the specification is determined according to the load calculation)
  • the support steel bar 13 is HRB400 steel bar with a diameter of 20mm (the vertical interval is 2m, which is used to fix the anchor hole pre-embedded pipe).
  • the pile bottom of hanging foot pile 1 falls on the smooth rock face of rock mass 200 and gets final product, need not enter rock, as shown in Figure 1.
  • the crown beam 300 and the waist beam 400 adopt conventional reinforced concrete structures.
  • the second group of anchor rods 2 is set in the vertical direction according to the excavation depth of the foundation pit.
  • the first anchor rod 2 is located at the bottom of the crown beam 300, and then laid downward at a distance of 2.5-3.5m, and the The last bolt 2 is set at the bottom of the pile 1 to form a locking foot bolt.
  • the incident angle of the anchor 2 in the soil 100 is selected from 15° to 35° according to the soil quality.
  • the incident angle of the anchor 2 in the rock mass 200 is 10° ° ⁇ 15°, the length of each anchor rod 2 is calculated and determined according to the load.
  • the width of the rock abutment 500 is flush with the outer edge of the waist beam 400 and greater than or equal to 300mm.
  • the embodiment of the present application also provides a construction method of a recoverable anchored prestressed stilt pile support structure, as shown in Figure 1, including the following steps:
  • the anchor bar 21 can be recovered after the construction is completed, which not only reduces the cost , and reduce the pollution of the surrounding environment.
  • the anchor rod 2 by passing the anchor rod 2 through the hanging pile 1 and the soil 100, and the hanging pile 1 and the rock mass 200, the hanging pile 1 passes through the anchor rod 2 and the rock mass 200 and the soil.
  • the bodies 100 are respectively solidified as a whole, which not only ensures the stability of the overall structure, but also reduces the cost of penetrating the foot pile 1 into the rock, and the construction is simple.
  • the recovery process of anchor rod 2 is:
  • the top fixing structure of the anchor bar 21 is first unlocked, and then the anchor component 22 is unlocked by using the detachable connection between the anchor bar 21 and the anchor assembly 22, so that the anchor bar 21 is unlocked, and finally the anchor bar 21 is unlocked.
  • Lifting the anchor bar 21 realizes recycling, and the anchor bar 21 can be reused, saving the cost of steel bar materials, the unlocking process of lifting and pressing down is simple, easy to realize, and simple and convenient in construction.
  • the thimble sleeve 224 inside lubricated with butter
  • the wedge-shaped thimble 223 outside lubricated with butter
  • the cover 225 is welded and connected, and then the whole is welded to the carrier 221;
  • the central axis of the tube 224 is coincident and the wedge-shaped thimble 223 is aligned with the wedge-shaped slideway 211 .
  • the site is flat, and the hanging pile 1 is positioned and set out.
  • the rotary drilling rig drills into the flat rock surface of the rock mass 200 to form a pile hole.
  • a top-drive drilling rig is used to drill the PVC pipe reserved in the pile body to form the anchor hole of the pile body.
  • the backing plate 231 is installed, a hydraulic jack is used to apply prestress to the anchor bar 21, and then the lock nut 232 is installed to lock the prestress, and finally the first group of anchor rods 2 is formed.
  • Top drive drilling rigs are used to drill between the piles to form anchor holes in the soil (rock) layer (choose from 120 to 200 mm according to the depth of the foundation pit and the characteristics of the rock and soil mass), and then grouting, construction of the waist beam 400, tension locking to form the second The first bolt 2 in the group of bolts 2; the grouting and tension locking process is the same as that of the first group of bolts 1.
  • the anchor bar 21 is pulled out to a certain length by a hydraulic jack, and then the anchor bar 21 is pulled out by a lifting machine or a vibrating hammer.
  • the anchor bar 21 of the main component can be recovered, and the anchoring method of the anchor bar 21 can effectively control the deformation of the foundation pit.
  • the anchor rod 2 can be integrated with the soil mass 100 and the rock mass 200 after being anchored, which not only improves the stability of the overall structure, but also reduces the pile-into-rock cost of the sling pile 1 and simplifies construction.
  • the anchor rod 2 is used as the main stress tendon and horizontal support structure of the suspension foot pile 1, and the deformation of the foundation pit can be effectively controlled through construction prestress.
  • the recycling of the anchor bar 21 not only reduces the material cost, but also reduces the pollution to the surrounding environment.

Abstract

本申请实施例公开了一种可回收锚入式预应力吊脚桩支护结构及施工方法，可回收锚入式预应力吊脚桩支护结构设于土岩组合基坑内，包括吊脚桩，设于基坑内土体的临空侧，吊脚桩的底端设于岩体上；锚杆，设有多个，多个锚杆分为两组，第一组锚杆竖直设于吊脚桩内且向下穿设在岩体内，第二组锚杆斜向穿设吊脚桩和土体，和/或斜向穿设吊脚桩和岩体；锚杆包括锚筋和锚固组件，锚固组件设于锚筋的位于土体或岩体内的底端，锚固组件与锚筋之间为可拆卸式连接。

Description

可回收锚入式预应力吊脚桩支护结构及施工方法
本申请要求在2021年07月01日提交中国专利局、申请号为202110742634.4的中国专利申请的优先权，以上申请的全部内容通过引用结合在本申请中。
技术领域
本申请涉及基坑支护技术领域，例如涉及一种可回收锚入式预应力吊脚桩支护结构及施工方法。
背景技术
随着国民经济的发展，城市化步伐的加快，地下空间开发规模越来越大，基坑开挖越来越大、越来越深；在土层覆盖较薄的滨海、丘陵及山地区域，开挖面上部为土、下部为岩的基坑越来越多，即土岩组合基坑。对于该类基坑常用的支护形式有吊脚桩、复合土钉墙及常规支护桩。其中吊脚桩一般采用吊脚桩+梯形岩肩护脚+锚杆锁脚，岩肩的宽度及锁脚锚杆的质量决定了支护结构的成败，安全度较低；石方爆破开挖过程中岩肩宽度较难控制，对于较深基坑岩肩宽度有限，从而支护深度有限，且桩底需嵌入岩肩一定深度，成孔打岩进度慢成本高。复合土钉墙结构一般采用微型桩+土钉+锚杆，仅适用于周边环境简单且开挖深度较浅的基坑；常规支护桩，需将桩底嵌入坑底一定深度，对于岩面较高的基坑，造价高、工期长。以上基坑常用的支护结构作为一种临时性结构，在地下结构完工后便完成服役并随基坑回填留置地下，从而造成钢材大量浪费。
发明内容
本申请实施例公开一种可回收锚入式预应力吊脚桩支护结构及施工方法。
本申请实施例公开一种可回收锚入式预应力吊脚桩支护结构，设于土岩组合基坑内，所述可回收锚入式预应力吊脚桩支护结构包括：
吊脚桩，设于土体的临空侧，所述吊脚桩的底端设于岩体上；
锚杆，所述锚杆设有多个，多个所述锚杆分为两组，两组锚杆中的第一组所述锚杆竖直设于所述吊脚桩内且向下穿设在所述岩体内，两组锚杆中的第二组所述锚杆斜向穿设在所述吊脚桩和所述土体内，和/或斜向穿设在所述吊脚桩和所述岩体内；
所述多个锚杆中的每个锚杆包括锚筋和锚固组件，所述锚固组件设于所述 锚筋的底端且位于所述土体或所述岩体内，所述锚固组件与所述锚筋之间为可拆卸式连接。
本申请实施例还公开一种可回收锚入式预应力吊脚桩支护结构的施工方法，包括如下步骤：
S1，在锚筋底端设置锚固组件以形成锚杆；
S2，在土体和岩体上分别钻锚孔，然后使得所述锚杆穿设所述吊脚桩和所述土体上所述锚孔，和/或使得所述锚杆穿设所述吊脚桩和所述岩体上所述锚孔，然后注浆；
S3，基坑内岩肩施工完毕后，将所述锚筋拔出实现锚杆回收。
附图说明
图1是本申请实施例的一种可回收锚入式预应力吊脚桩支护结构在基坑内的设置示意图；
图2是本申请实施例的一种可回收锚入式预应力吊脚桩支护结构中锚杆的结构示意图；
图3是本申请实施例的一种可回收锚入式预应力吊脚桩支护结构中锚杆的顶端固定结构示意图；
图4是图2中A-A截面示意图；
图5是图2中B-B截面示意图；
图6是本申请实施例的一种可回收锚入式预应力吊脚桩支护结构中隔离支架的结构示意图；
图7是图1中C-C截面示意图。
图中：
100.土体；200.岩体；300.冠梁；400.腰梁；500.岩肩；
1.吊脚桩；11.纵筋；12.箍筋；13.支架钢筋；
2.锚杆；21.锚筋；22.锚固组件；221.承载台；222.楔形压片；223.楔形顶针；224.顶针套管；225.封盖；226.临时固定片；227.临时螺钉；23.锁定组件；231.垫板；232.锁定螺母；24.隔离支架；241.中心通孔；242.注浆管孔；25.注浆管；26.注浆体；27.隔离套管。
具体实施方式
下面结合附图和实施例对本申请实施例进行说明。可以理解的是，此处所 描述的具体实施例仅仅用于解释本申请，而非对本申请的限定。另外还需要说明的是，为了便于描述，附图中仅示出了与本申请相关的部分而非全部结构。
在本申请的描述中，除非另有明确的规定和限定，术语“相连”、“连接”、“固定”应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或成一体；可以是机械连接，也可以是电连接；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通或两个元件的相互作用关系。对于本领域的普通技术人员而言，可以结合具体情况理解上述术语在本申请中的具体含义。
在本申请中，除非另有明确的规定和限定，第一特征在第二特征之“上”或之“下”可以包括第一和第二特征直接接触，也可以包括第一和第二特征不是直接接触而是通过它们之间的另外的特征接触。而且，第一特征在第二特征“之上”、“上方”和“上面”包括第一特征在第二特征正上方和斜上方，或仅仅表示第一特征水平高度高于第二特征。第一特征在第二特征“之下”、“下方”和“下面”包括第一特征在第二特征正下方和斜下方，或仅仅表示第一特征水平高度小于第二特征。
在本实施例的描述中，术语“上”、“下”、“右”、等方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述和简化操作，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请的限制。此外，术语“第一”、“第二”仅仅用于在描述上加以区分，并没有特殊的含义。
本申请实施例首先提供一种可回收锚入式预应力吊脚桩支护结构，针对相关技术中应用的土岩组合基坑支护结构存在的钢材浪费和施工复杂的问题，为周边环境复杂、深度深、开挖面积大的土岩组合基坑，提供一种避免钢材浪费、降低成本以及施工简便的吊脚桩支护结构，如图1所示，设于土岩组合基坑内，其中，土体100的下方为岩体200，可回收锚入式预应力吊脚桩支护结构包括吊脚桩1和锚杆2，吊脚桩1设于基坑内土体100的临空侧，吊脚桩1的底端设于岩体200上；锚杆2设有多个，多个锚杆2分为两组，第一组锚杆2竖直设于吊脚桩1内且向下穿设在岩体200内，第二组锚杆2斜向穿设吊脚桩1和土体100，和/或斜向穿设吊脚桩1和岩体200；其中，锚杆2包括锚筋21和锚固组件22，锚固组件22设于锚筋21的的底端且位于土体100或岩体200内，锚固组件22与锚筋21之间为可拆卸式连接。
结合图1，本申请实施例中，吊脚桩1设置在岩体200上而不入岩体200， 通过锚杆2设于吊脚桩1内并向下穿设岩体200形成对吊脚桩1的固定，锚杆2和吊脚桩1固为整体，不仅保证了整体结构的稳定性，而且减少了吊脚桩1入岩的成本，施工简单。本实施例中通过将锚筋21设置为竖直和斜向两组，分别穿设吊脚桩1和土体100，以及吊脚桩1和岩体200，通过在吊脚桩1的外侧施加预应力可有效控制基坑变形，提高了吊脚桩1和土体100以及吊脚桩1和岩体200之间的固定强度，支护结构稳定可靠，施工方便。通过在锚筋21底端设置可拆卸的锚固组件22，便于施工结束后回收锚筋21，从而实现锚杆2回收以重复利用，不仅降低了成本，而且减轻了对周边环境的污染。
在一实施例中，第一组锚杆2和第二组锚杆2具有相同的结构，只是锚入角度不同，多个锚杆2之间的间距根据实际计算设置，在一些实施例中，第一组锚杆2的底端穿设在岩体200内的部分可低于岩肩500的底端，以达到更好的锚固效果，第二组锚杆2在土体100中的斜向锚入角度为15°-35°(例如，斜向锚入角度可以图1中的水平方向为参考基准线)，在岩体200中的斜向锚入角度为10°-15°，各道锚杆2的长度根据所受载荷计算确定。
在一实施例中，第二组锚杆2斜向设置，参考图1，斜向可为竖直方向与水平方向之间的任意方向，或非竖直方向之外的任意方向。
在一实施例中，如图2所示，锚固组件22包括承载台221、楔形压片222、楔形顶针223、顶针套管224和封盖225，其中，
承载台221设有中心通孔，中心通孔为圆台孔；圆台孔的顶孔的孔径小于底孔的孔径。
楔形压片222设有至少两个，至少两个楔形压片222围设锚筋21的底端并与锚筋21的底端螺纹连接，楔形压片222穿设在中心通孔内并固定；其中，锚筋21的底端通过套丝方式加工外螺纹，图4所示采用两个楔形压片222组合成圆台并加工内螺纹使之与锚筋21的底端外螺纹配套连接，同时，两个楔形压片222组合成的圆台能够穿设在承载台221的中心通孔内并与之形成整体，本实施例中，楔形压片222的底部与承载台221的接缝处设置临时固定片226和临时螺钉227，临时固定片226覆盖在接缝处并通过临时螺钉227固定在承载台221上，实现二者固定一体。为了便于后期回收，临时固定片226采用塑料材质或其他易于剪切断裂的材质。
楔形顶针223设有至少两个，至少两个楔形顶针223设于锚筋21的底端的端面，锚筋21的底端设置至少两个楔形滑道211，楔形顶针223与楔形滑道211相对应设置，楔形顶针223能够滑入楔形滑道211以使得楔形压片222与锚筋 21分离；如图5，楔形顶针223设有三个，与图4中所示锚筋21上三个楔形滑道211相对应设置，当锚筋21向下运动时，楔形顶针223能够滑入楔形滑道211内并将两个楔形压片222撑开，使得楔形压片222与锚筋21分离，便于锚筋21的回收。可以理解，楔形顶针223、楔形滑道211和楔形压片222的尺寸要预先进行设计计算以满足上述回收要求。
顶针套管224套设在至少两个楔形顶针223的外侧；结合图2和图5，顶针套管224为环形套管如钢管件，顶针套管224的内径大于锚筋21的外径以便于锚筋21的移动以及对锚筋21的移动进行轴向限位。顶针套管224套设在三个楔形顶针223的外圆周以限定三个楔形顶针223的位置，当楔形顶针223滑入楔形滑道211内时，顶针套管224能够限定楔形顶针223的周向位移以保证锚筋21的竖直滑入，确保楔形压片222顺利与锚筋21分离。
封盖225罩设楔形顶针223和顶针套管224并固定于承载台221上，顶针套管24和楔形顶针223均与封盖225固定连接。
如图2所示，封盖225采用开口向上的凹槽结构，开口能够罩设楔形顶针223和顶针套管224后固定在承载台221的底面，以将楔形顶针223和顶针套管224密封，同时楔形顶针223和顶针套管224固定在封盖225的底端内侧壁上，以实现对锚杆2的底端固定。在没有特别说明的情况下，本申请实施例中涉及的固定方式均为焊接固定，所采用的金属件如钢筋之间均为焊接连接固定。
在一实施例中，锚杆2还包括锁定组件23，锁定组件23包括垫板231和锁定螺母232，锚筋21的顶端穿设吊脚桩1和垫板231并与锁定螺母232锁紧以将锚筋21固定张紧。
以第一组锚杆2为例，如图3，锚筋21的顶端依次穿设吊脚桩1和冠梁300，垫板231设置在冠梁300的顶端，锚筋21的顶端穿设垫板231并与锁定螺母232连接，可以为锚杆2提供张拉预应力，便于固定和浇注。在回收锚杆2时，采用液压千斤顶对锚筋21施加拉力，使得锁定螺母232与垫板231之间脱离，然后拆除锁定螺母232，便于后期拔出锚筋21。对于第二组锚杆2，锚筋21的顶端通过锁定组件23固定在吊脚桩1的外侧壁上。
在一实施例中，锚杆2还包括隔离支架24，隔离支架24设有多个，多个隔离支架24沿锚筋21长轴方向(例如，参见图2中的长轴方向L1)间隔设置，锚筋21穿设在隔离支架24上以限位。
在一实施例中，锚杆2还包括注浆管25，注浆管25穿设在隔离支架24上以限位。
如图2和图6所示，隔离支架24为平板件，隔离支架24上设有中心通孔241和注浆管孔242，注浆管孔242设有两个，注浆管25包括高压注浆管和常压注浆管，锚筋21穿设在中心通孔241内，注浆管25穿设在多个注浆管孔242内，通过纵向设置的多道隔离支架24(即，多道隔离支架24沿着锚筋21间隔设置)，可以维持锚筋21和注浆管25的竖直度，确保锚筋21的顺利拔出回收。施工时，先通过常压注浆管注入水泥浆至孔口溢浆，待水泥浆终凝后2h内通过高压注浆管进行二次注浆，压力不小于2MPa，形成注浆体26。
在一实施例中，吊脚桩1包括纵筋11、箍筋12和支架钢筋13，多个箍筋12间隔设置在纵筋11的长轴方向，多个纵筋11贴靠箍筋12的内侧壁间隔设置，支架钢筋13的两端分别连接箍筋12的内侧壁以将箍筋12所在平面划分为临土弓形区域和临空弓形区域，锚筋21设置在临土弓形区域。
在一示例中，可在每个箍筋12上连接一个支架钢筋13。
在一示例中，可在每两个箍筋12中的一个箍筋12上连接一个支架钢筋13，例如，若每个箍筋12之间的间隔距离为u，则可每2u的间距距离上设置一个支架钢筋13。但不限制于此类支架钢筋13的设置方式。
结合图1和图7，在一个箍筋12平面上，箍筋12呈圆环形，支架钢筋13的两端连接在箍筋12内将圆环分为两个区域，临土弓形区域(图7中上方区域)和临空弓形区域(图7中下方区域)，例如，支架钢筋13的高度为四分之一圆环直径长度，便于在临土侧设置锚筋21以提高锚固强度。纵筋11、箍筋12和支架钢筋13相互焊接固定形成钢筋笼，便于落在岩体200上方以浇筑成型。
在一实施例中，锚筋21在临土弓形区域内的圆弧段贴靠箍筋12内侧壁且与纵筋11交替设置，锚筋21在临土弓形区域内的直线段贴靠支架钢筋13间隔设置。
例如，临土弓形区域为临土半圆区域，临空弓形区域为临空半圆区域。
如图7，以第一组锚杆2为例，在临土半圆区域内，锚筋21贴靠箍筋12内侧壁和支架钢筋13内侧壁设置，分别形成半圆形辐射状布设和直线布设的锚筋组，具体锚筋21数量根据所受载荷计算确定。例如，锚筋21均匀间隔设置，纵筋11均匀间隔设置，本实施例中，箍筋12的内侧壁设置七根锚筋21，支架钢筋13内侧设置三根锚筋21，每根锚筋21长度方向上锚入岩体内深度大于或等于6m，以提供足够的锚固强度。
在一实施例中，锚杆2还包括隔离套管27，隔离套管27套设在锚筋21上，隔离套管27的底端止抵在承载台221上方。
如图2，隔离套管27套设在锚筋21的外侧用于隔离锚筋21和注浆体26，便于锚筋21的后期拔出回收。隔离套管27采用塑料波纹管或金属波纹管，在安装隔离套管27前可在锚筋21外部涂刷防锈剂及黄油，保证足够润滑度，便于锚筋21的回收。
例如，隔离套管27与锚筋21之间、顶针套管224与楔形顶针223之间、楔形夹片222与承载台221之间、楔形夹片222与锚筋21之间均涂抹有润滑油如黄油，便于锚杆2回收。
下面通过一个实施例来对本申请实施例中的一种可回收锚入式预应力吊脚桩支护结构进行描述。
实施例1：
如图1-图7，一种可回收锚入式预应力吊脚桩支护结构，第一组锚杆2为桩身可回收预应力锚杆，第二组锚杆2为土(岩)体可回收预应力锚杆，两组锚杆2的结构相同。锚筋21采用预应力螺纹钢，底端套丝且在底端端头进行2mm倒角，套丝长度为承载体221的厚度+10mm，强度及直径根据所受荷载计算确定；隔离套管27可采用塑料波纹管或金属波纹管，注浆体26由纯水泥浆注浆形成，承载体221为Q345钢材制作的圆柱体，厚度不小于50mm，直径略小于钻孔直径，圆柱体中心开圆台形孔，圆台形孔上底面直径为锚筋21直径+10mm，下底面直径为上底面直径+承载体221厚度×tan25°×2；楔形夹片222采用Q345钢材制作，内部套丝与锚筋11底端套丝配套，两个楔形夹片222组成空心圆台可与锚筋21底端螺纹连接，圆台外部尺寸略小于承载体221中部圆台形孔尺寸；楔形滑道211在锚筋21底端套丝后刨铣形成(楔形滑道211最深处深度为锚筋21直径的1/5且不小于5mm)，临时固定片226采用硬质塑料制作(长度覆盖楔形夹片222的1/5，并超过临时固定螺丝227)，临时固定螺丝227采用直径6mm普通螺丝；顶针套管224采用无缝钢管(内径略大于锚筋21底端套丝后的外径)，楔形顶针223采用Q345钢材制作(外形尺寸与楔形滑道211相匹配)，封盖225采用Q235钢板制作，顶针套管224、楔形顶针223及封盖225之间采用焊接连接，垫板231采用Q345钢板制作(250mm×250mm×20mm，中部开孔，开孔直径大于锚筋21直径+40mm)，锁定螺母232采用与锚筋21螺纹钢配套的成品螺母，隔离支架24采用聚乙烯材料制作(直径略小于钻孔直径，厚度不小于15mm，中心通孔241作为锚筋孔，直径不小于外套有隔离套管27后的锚筋21的外径+10mm，注浆管25包括常压注浆管和高压注浆管，相应地，注浆管孔242包括常压注浆管孔和高压注浆管孔，其中，常压注浆管孔的 内径大于或等于常压注浆管的外径+10mm，高压注浆管孔的内径大于或等于高压注浆管的外径+10mm，常压注浆管采用PE塑料管(外径25mm，承压大于或等于1MPa，底端开口)，高压注浆管采用PE塑料管(外径25mm，承压大于或等于4MPa，底端封口，在管身设置直径5mm，周向大于或等于5个，轴向间距小于或等于15cm)。第一组锚杆2中受拉纵筋及锚固筋在桩身临土半圆区域内呈辐射形布设，如图7所示，锚筋21数目根据所受荷载计算确定且大于或等于7根；锚固筋在桩身临空侧1/4区域内直线形布设大于或等于3根；锚杆2长度锚入坑底岩体大于或等于6m。
吊脚桩1中，纵筋11采用热轧带肋钢筋(强度及直径根据所受荷载计算确定)，螺旋箍筋12采用热轧光圆钢筋(强度及直径根据所受荷载计算确定)，混凝土采用商品混凝土(规格根据所受荷载计算确定)，支架钢筋13采用HRB400直径20mm钢筋(竖向间隔2m，用于固定锚孔预埋管)。吊脚桩1的桩底落于岩体200的平整岩面即可，不用入岩，如图1。冠梁300及腰梁400采用常规钢筋混凝土结构。
第二组锚杆2沿竖向方向设置道数根据基坑开挖深度进行设置，一般第一道锚杆2位于冠梁300底，然后以2.5～3.5m间距向下布设，且在吊脚桩1桩底位置设置最后一道锚杆2形成锁脚锚杆，土体100中的锚杆2入射角度根据土质情况在15°～35°选择，岩体200中锚杆2的入射角度在10°～15°选择，各道锚杆2长度根据所受荷载计算确定。岩肩500宽度与腰梁400外缘齐平且大于或等于300mm。上述的提供的可回收锚入式预应力吊脚桩支护结构，吊脚桩1不入岩，施工简单；锚杆2可回收，节约钢材成本。
本申请实施例还提供一种可回收锚入式预应力吊脚桩支护结构的施工方法，如图1，包括如下步骤：
S1，在锚筋21底端设置锚固组件22以形成锚杆2；
S2，在土体100和岩体200上分别钻锚孔，然后使得锚杆2穿设吊脚桩1和土体100上锚孔，和/或使得锚杆2穿设吊脚桩1和岩体200上锚孔，最后注浆；
S3，基坑内岩肩500施工完毕后，将锚筋21拔出实现锚杆2回收。
本申请实施例的一种可回收锚入式预应力吊脚桩支护结构的施工方法，通过在锚筋21底端设置锚固组件22，在施工完毕后可回收锚筋21，不仅降低了成本，而且减轻了对周边环境的污染。本申请实施例的施工方法中，通过将锚杆2分别穿设吊脚桩1和土体100，以及吊脚桩1和岩体200，吊脚桩1通过锚 杆2与岩体200和土体100分别固为整体，不仅保证了整体结构的稳定性，而且减少了吊脚桩1入岩的成本，施工简单。
在一实施例中，结合图2和图3，锚杆2回收的过程为：
S31，对锚筋21施加向上的拉力使得锁定螺母232和垫板231脱离，拆除锁定螺母232；
S32，对锚筋21施加沿轴向向下的冲击力，使得锚筋21的底端滑入顶针套管224内，同时楔形顶针223滑入楔形滑道211内，使得楔形夹片22与锚筋21的底端分离；
S33，向上拔出锚筋21，实现回收。
可以理解，锚杆2回收时，首先解锁锚筋21的顶部固定结构，然后利用锚筋21与锚固组件22之间的可拆卸式连接方式，解锁锚固组件22，使得锚筋21解锁，最后上提锚筋21实现回收，锚筋21可以实现重复利用，节约钢筋材料成本，上提和下压的解锁过程简单，易于实现，施工简单方便。
实施例2：
下面通过一个实施例描述本申请实施例的一种可回收锚入式预应力吊脚桩支护结构的施工方法，包括锚杆2锚入和锚杆2回收，如下：
(1)锚杆2的安装：
对锚筋21底端套丝，然后刨铣形成楔形滑道211，在套丝位置涂抹黄油。
将楔形夹片222(内部套丝与锚筋21底端套丝配套)外部涂抹黄油后与锚筋21组合，然后穿过承载体221并压紧，通过临时固定片226及临时固定螺丝227进行固定。
将顶针套管224(内部涂抹黄油润滑)、楔形顶针223(外部涂抹黄油润滑)、封盖225焊接连接后再将其整体与承载体221焊接；安装过程要使锚筋21中轴线与顶针套管224的中轴线重合且楔形顶针223与楔形滑道211对齐。
对锚筋21外部涂刷防锈剂及黄油然后将隔离套管27套于外侧；
将锚筋21、注浆管25(包括常压注浆管及高压注浆管)平行放置，然后每隔1.5m安装隔离支架24，通过绑丝固定。
(2)整体支护结构实施方式：
场地平整，吊脚桩1定位放线。
旋挖钻机钻进至岩体200的平整岩面形成桩孔。
将纵筋11、螺旋箍筋12及支架钢筋13组合安装形成钢筋笼，并在锚筋21位置埋设与锚杆2成孔直径(根据桩径大小及基坑特征在60～100mm选择)相 同的PVC管，PVC管内部注满水两端封口与钢筋笼绑扎固定，底部齐平桩底、顶部齐平冠梁300顶。
安装钢筋笼至桩孔，浇筑混凝土形成吊脚桩1。
开挖基坑第一层土至冠梁300底，破除桩头施工冠梁300。
采用顶驱钻机在桩身预留PVC管位置钻进形成桩身锚孔。
安装锚杆2至桩身锚孔，然后通过常压注浆管注入水泥浆至孔口溢浆为止，待水泥浆终凝后2h内通过高压注浆管进行二次注浆(压力不小于2MPa)，形成注浆体26。
安装垫板231，采用液压千斤顶对锚筋21施加预应力，然后安装锁定螺母232锁定预应力，最后形成第一组锚杆2。
开挖基坑第二层土至第一道腰梁400底。
采用顶驱钻机在桩间钻进形成土(岩)层锚杆孔(根据基坑深度及岩土体特征在120～200mm选择)，然后注浆、施工腰梁400、张拉锁定形成第二组锚杆2中的第一道锚杆2；其中注浆和张拉锁定工艺与第一组锚杆1相同。
开挖基坑第三层土至第二道腰梁400底，施工对应位置的锚杆2和腰梁400。......开挖基坑至最后一道腰梁400底，施工对应位置锚杆2及腰梁400。
爆破开挖石方至基坑底，临近桩边石方采用控制静爆形成岩肩500。
(3)锚杆2回收实施方式：
采用液压千斤顶对锚筋21施加拉力使锁定螺母232与垫板231间脱离，然后拆除锁定螺母232。
通过锤击对锚筋21施加与锚筋21中轴重合的冲击力，使锚筋21底端滑入顶针套管224，从而楔形顶针223滑入楔形滑道211，进而使楔形夹片222与锚筋21底端分离。
通过液压千斤顶将锚筋21拔出一定长度，然后采用起重机械或振动锤将锚筋21拔出。
上述施工方法中，适用于土岩组合基坑的支护结构，施工过程安全可靠，主要部件锚筋21可回收，锚筋21的锚入方式可以有效控制基坑变形。锚杆2在锚入后可与土体100及岩体200固为整体，不仅提高了整体结构的稳定性，而且减少的吊脚桩1的桩入岩成本，施工简化。锚杆2作为吊脚桩1的主要受力筋及水平支撑结构，通过施工预应力可以有效控制基坑变形。通过锚筋21回收后的重复利用，不仅降低了材料成本，而且减轻了对周边环境的污染。
本申请的上述实施例仅仅是为了清楚说明本申请所作的举例，而并非是对 本申请的实施方式的限定。对于所属领域的普通技术人员来说，能够进行各种明显的变化、重新调整和替代而不会脱离本申请的保护范围。这里无需也无法对所有的实施方式予以穷举。凡在本发明构思之内所作的任何修改、等同替换和改进等，均应包含在本申请权利要求的保护范围之内。

Claims (10)

  1. 一种可回收锚入式预应力吊脚桩支护结构，设于土岩组合的基坑内，所述可回收锚入式预应力吊脚桩支护结构包括：
    吊脚桩(1)，设于土体(100)的临空侧，所述吊脚桩(1)的底端设于岩体(200)上；
    锚杆(2)，所述锚杆(2)设有多个，多个所述锚杆(2)分为两组，两组锚杆(2)中的第一组所述锚杆(2)竖直设于所述吊脚桩(1)内且向下穿设在所述岩体(200)内，两组锚杆(2)中的第二组所述锚杆(2)斜向穿设在所述吊脚桩(1)和所述土体(100)内，和/或斜向穿设在所述吊脚桩(1)和所述岩体(200)内；
    所述多个锚杆(2)中的每个锚杆(2)包括锚筋(21)和锚固组件(22)，所述锚固组件(22)设于所述锚筋(21)的底端且位于所述土体(100)或所述岩体(200)内，所述锚固组件(22)与所述锚筋(21)之间为可拆卸式连接。
  2. 根据权利要求1所述的可回收锚入式预应力吊脚桩支护结构，其中，所述锚固组件(22)包括：
    承载台(221)，所述承载台(221)设有中心通孔，所述中心通孔为圆台孔；
    楔形压片(222)，设有至少两个，至少两个所述楔形压片(222)围设所述锚筋(21)的所述底端并与所述锚筋(21)的所述底端螺纹连接，至少两个所述楔形压片(222)穿设在所述中心通孔内并固定；
    楔形顶针(223)，设有至少两个，至少两个所述楔形顶针(223)设于所述锚筋(21)的所述底端的端面，所述锚筋(21)的所述底端设置至少两个楔形滑道(211)，所述至少两个楔形顶针(223)与所述至少两个楔形滑道(211)相对应设置，所述至少两个楔形顶针(223)能够分别滑入所述至少两个楔形滑道(211)以使得所述至少两个楔形压片(222)与所述锚筋(21)分离；
    顶针套管(224)，所述顶针套管(224)套设在至少两个所述楔形顶针(223)的外侧；
    封盖(225)，所述封盖(225)罩设所述至少两个楔形顶针(223)和所述顶针套管(224)并固定于所述承载台(221)上，所述顶针套管(224)和所述至少两个楔形顶针(223)分别与所述封盖(225)固定连接。
  3. 根据权利要求1所述的可回收锚入式预应力吊脚桩支护结构，其中，所述每个锚杆(2)还包括锁定组件(23)，所述锁定组件(23)包括垫板(231)和锁定螺母(232)，所述锚筋(21)的顶端穿设所述吊脚桩(1)和所述垫板(231)并与所述锁定螺母(232)锁紧以将所述锚筋(21)固定张紧。
  4. 根据权利要求1所述的可回收锚入式预应力吊脚桩支护结构，其中，所述每个锚杆(2)还包括隔离支架(24)，所述隔离支架(24)设有多个，多个所述隔离支架(24)沿所述锚筋(21)长轴方向间隔设置，所述锚筋(21)穿设在所述多个隔离支架(24)上以限位。
  5. 根据权利要求4所述的可回收锚入式预应力吊脚桩支护结构，其中，所述每个锚杆(2)还包括注浆管(25)，所述注浆管(25)穿设在所述隔离支架(24)上以限位。
  6. 根据权利要求1所述的可回收锚入式预应力吊脚桩支护结构，其中，所述吊脚桩(1)包括多个纵筋(11)、多个箍筋(12)和支架钢筋(13)，多个所述箍筋(12)间隔设置在所述纵筋(11)的长轴方向，多个所述纵筋(11)贴靠所述多个箍筋(12)的内侧壁间隔设置，所述支架钢筋(13)的两端分别连接所述多个箍筋(12)中的一个箍筋(12)的内侧壁以将所述一个箍筋(12)所在平面划分为临土弓形区域和临空弓形区域，所述锚筋(21)设置在所述临土弓形区域。
  7. 根据权利要求6所述的可回收锚入式预应力吊脚桩支护结构，其中，所述锚筋(21)在所述临土弓形区域内的圆弧段贴靠所述箍筋(12)内侧壁且与所述纵筋(11)交替设置，所述锚筋(21)在所述临土弓形区域内的直线段贴靠所述支架钢筋(13)间隔设置。
  8. 根据权利要求2所述的可回收锚入式预应力吊脚桩支护结构，其中，所述每个锚杆(2)还包括隔离套管(27)，所述隔离套管(27)套设在所述锚筋(21)上，所述隔离套管(27)的底端止抵在所述承载台(221)上方。
  9. 一种可回收锚入式预应力吊脚桩支护结构的施工方法，包括如下步骤：
    步骤1(S1)，在锚筋(21)底端设置锚固组件(22)以形成锚杆(2)；
    步骤2(S2)，在土体(100)和岩体(200)上分别钻锚孔，然后使得所述锚杆(2)穿设吊脚桩(1)和所述土体(100)上所述锚孔，和/或使得所述锚杆(2)穿设所述吊脚桩(1)和所述岩体(200)上所述锚孔，然后注浆；
    步骤3(S3)，基坑内岩肩(500)施工完毕后，将所述锚筋(21)拔出实现锚杆(2)回收。
  10. 根据权利要求9所述的可回收锚入式预应力吊脚桩支护结构的施工方法，其中，所述锚杆(2)回收的过程为：
    步骤31(S31)，对锚筋(21)施加向上的拉力使得锁定螺母(232)和垫板(231)脱离，拆除所述锁定螺母(232)；
    步骤32(S32)，对所述锚筋(21)施加沿轴向向下的冲击力，使得所述锚筋(21)的底端滑入顶针套管(224)内，同时楔形顶针(223)滑入楔形滑道(211)内，使得楔形夹片(222)与所述锚筋(21)的底端分离；
    步骤33(S33)，向上拔出所述锚筋(21)，实现回收。
PCT/CN2021/141916 2021-07-01 2021-12-28 可回收锚入式预应力吊脚桩支护结构及施工方法 WO2023273253A1 (zh)

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