CN110670599A - Hollow grouting prestressed anchor rod and construction method thereof - Google Patents

Hollow grouting prestressed anchor rod and construction method thereof Download PDF

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Publication number
CN110670599A
CN110670599A CN201910845916.XA CN201910845916A CN110670599A CN 110670599 A CN110670599 A CN 110670599A CN 201910845916 A CN201910845916 A CN 201910845916A CN 110670599 A CN110670599 A CN 110670599A
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CN
China
Prior art keywords
anchor
hollow
hole
rod body
grouting
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Granted
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CN201910845916.XA
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CN110670599B (en
Inventor
刘思谋
刘丽杰
刘思广
杨文蛟
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Mcc Communication Construction Group Co Ltd
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Mcc Communication Construction Group Co Ltd
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Priority to CN201910845916.XA priority Critical patent/CN110670599B/en
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    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D17/00Excavations; Bordering of excavations; Making embankments
    • E02D17/02Foundation pits
    • E02D17/04Bordering surfacing or stiffening the sides of foundation pits
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D17/00Excavations; Bordering of excavations; Making embankments
    • E02D17/20Securing of slopes or inclines
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D5/00Bulkheads, piles, or other structural elements specially adapted to foundation engineering
    • E02D5/74Means for anchoring structural elements or bulkheads

Abstract

The invention discloses a hollow prestressed anchor rod and a construction method thereof. Wherein the anchor head comprises a cylindrical connecting part and an expansion part consisting of a plurality of spherical-segment-shaped shells. After the hollow prestressed anchor rod is constructed and installed, the maximum tensile force which can be achieved by the hollow prestressed anchor rod is greatly increased compared with that of a traditional anchor rod, so that the safety performance of a supporting structure consisting of the anchor rod is improved.

Description

Hollow grouting prestressed anchor rod and construction method thereof
Technical Field
The invention relates to the technical field of civil engineering construction tools, in particular to a hollow grouting prestressed anchor rod and a construction method using the same.
Background
The prestressed anchor rod is a tool for reinforcing rock mass, can improve the stress of row piles in a deep foundation pit, and improves the stability of a side slope. The prestressed anchor rods are commonly used in building engineering, highways, railways and hydraulic engineering to reinforce soil bodies around high slopes and deep foundation pits, and are also widely applied as a support structure in the initial stage of a tunnel. When the anchor rod is used, firstly, a hole is drilled on a soft rock stratum or a sliding surface through the drilling machine, then one end of the anchor rod is anchored in a hard rock stratum, and then the other end of the anchor rod is screwed up and tensioned by the nut, so that the soil body or the rock body is stressed and reinforced, the stability of the soil body or the rock body is improved, and collapse is avoided. The hollow grouting anchor rod is generally composed of a nut, a backing plate, a grout stop plug, a hollow anchor rod body and an anchor head, when the hollow grouting anchor rod is used, an anchor rod hole is drilled firstly, the rod body and the anchor head stretch into the anchor rod hole, then cement slurry is poured into the anchor rod hole, and finally tensioning is carried out.
The traditional construction method of the hollow grouting anchor rod has multiple working procedures and is not easy to ensure the quality. When the construction is finished and the tensioning is carried out, the designed tension value can not be achieved frequently, and the stability of the supporting structure is influenced. In addition, the water of aquifer in the soil body can dilute the grout, influence the intensity of grout, still can accelerate the corrosion speed of stock simultaneously, influence supporting construction's stability. Unsafe factors are brought, roof collapse or collapse accidents happen on a construction site seriously, and great loss is caused.
Disclosure of Invention
The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a hollow grouting prestressed anchor rod and a construction method thereof, which can improve anchoring force of the anchor rod and make a supporting structure composed of the anchor rod more stable.
In order to achieve the above object, the present invention provides a hollow grouting prestressed anchor rod, including a hollow rod body, an anchor head, a nut and a backing plate, wherein the surface of the hollow rod body is provided with an external thread, the anchor head is arranged at the anchoring end of the hollow rod body, and the nut and the backing plate are arranged at the free end of the hollow rod body; one end of the anchor head is an expansion part consisting of a plurality of spherical-segment-shaped shells, and the other end of the anchor head is a cylindrical connecting part; one end of the shell is integrally connected with the connecting part, and convex teeth are arranged on the outer surface of the shell; the inner wall of connecting portion be provided with external screw thread assorted internal thread, the anchor head passes through connecting portion cup joint is in the tip of the cavity body of rod.
Furthermore, the anchoring end of the hollow rod body is conical.
Furthermore, one side of the connecting part, which is close to the expansion part, is not provided with an internal thread, one side of the connecting part, which is far away from the expansion part, is provided with an internal thread, and the inner diameter of the connecting part without the internal thread section is larger than that of the connecting part with the internal thread section.
Furthermore, a limiting ring is arranged on the hollow rod body close to the anchoring end to prevent the anchor head from falling off from the anchoring end.
Furthermore, the free end of the hollow rod body is provided with a polygonal groove along the axial direction, and the polygonal groove is used for being matched with a spanner to rotate the hollow rod body.
Further, a pulp outlet hole is arranged on one point 1/5-1/2 of the hollow rod body along the radial direction, and the hole diameter of the outer side of the pulp outlet hole is smaller than that of the inner side of the pulp outlet hole; and a hole plug matched with the shape of the slurry outlet hole is arranged in the slurry outlet hole.
On the other hand, the invention also provides a construction method of the hollow grouting prestressed anchor rod, which adopts the hollow grouting prestressed anchor rod and comprises the following steps:
s1, manufacturing a reinforced concrete ring beam at a preset position of a soil body, reserving an anchor rod hole position on the ring beam, and reserving a grouting hole leading to the anchor rod hole on the ring beam;
s2, drilling holes in the anchor rod hole sites according to a preset angle to form anchor rod holes;
s3, reaming the bottom of the anchor rod hole to form an anchoring cavity, and then cleaning the anchor rod hole and the anchoring cavity;
s4, sleeving the anchor head at the anchoring end of the hollow rod body and extending into the anchor rod hole to enable the anchor head to be located in the anchoring cavity, and sequentially installing a pedestal, a backing plate and a nut at the free end of the hollow rod body;
s5, rotating the hollow rod body to enable the expansion part of the anchor head to expand under squeezing and expanding of the hollow rod body, then pouring cement slurry into the anchoring cavity and the bottom of the anchor rod hole through the inner cavity of the hollow rod body until the upper layer of the cement slurry is close to the slurry outlet hole, and stopping grouting to form an anchoring section;
s6, after the cement strength of the anchoring section reaches a design value, tensioning the anchor rod until the tension reaches the design value;
s7, injecting cement slurry into the anchor rod hole through the grouting hole until the cement slurry flows out of the free end of the hollow rod body, and then stopping grouting to form a free section;
and S8, plugging the grouting hole, and then sealing the anchor.
Further, an inclined plane of pedestal with the ring beam laminating, another inclined plane of pedestal perpendicular to the stock.
According to the above description and practice, the hollow grouting prestressed anchor rod of the present invention adopts the expansion part composed of several segmental shells, and the expanded anchoring cavity is arranged at the bottom of the anchor rod hole, so as to raise the upper limit of the tension force which can be reached by the anchor rod. In addition, set up out the thick liquid hole at the middle part of the cavity body of rod, changed traditional slip casting direction, can improve the intensity of grout to a certain extent with the downthehole ponding discharge of stock to protect the stock, reduced the corrosion speed of stock, promoted the protective structure's that the stock constitutes the security performance. In addition, under the same design tension value, the hollow grouting prestressed anchor rod can reduce the length of a hollow rod body, save materials and reduce the workload of drilling, thereby reducing the construction cost.
Drawings
Fig. 1 is a schematic view showing a hollow grouting prestressed anchor according to an embodiment of the present invention in a state where a divergent portion is not spread when in use.
Fig. 2 is a schematic view showing a hollow grouting prestressed anchor rod according to an embodiment of the present invention, in a state after grouting of an anchoring section in use.
Fig. 3 is a schematic view showing a state after a free section is grouted in use of the hollow grouting prestressed anchor according to one embodiment of the present invention.
FIG. 4 is a schematic view showing the detailed structure of the anchor head in the hollow grouting prestressed anchor rod according to one embodiment of the present invention.
Fig. 5 is a schematic view illustrating a construction process of a hollow grouting prestressed anchor according to an embodiment of the present invention.
In the figure:
1. the device comprises a hollow rod body, 2, an anchor head, 3, a nut, 4, a base plate, 5, a limiting ring, 6, an anchor rod hole, 7, a ring beam, 8, a pedestal, 9 and a support;
11. a groove 12, a grout outlet 13 and a hole plug;
21. an expansion portion 22, a connection portion;
61. an anchor lumen;
71. and (4) grouting holes.
Detailed Description
The embodiment of the hydraulic device of the energy storage type ladle long nozzle manipulator related to the invention will be described with reference to the attached drawings. Those of ordinary skill in the art will recognize that the described embodiments can be modified in various different ways, without departing from the spirit and scope of the present invention. Accordingly, the drawings and description are illustrative in nature and not intended to limit the scope of the claims. Furthermore, in the present description, the drawings are not to scale and like reference numerals refer to like parts.
Example 1
FIG. 1 is a schematic view illustrating a state in which a divergent portion of a hollow prestressed grouting bolt according to an embodiment of the present invention is not spread. Fig. 2 is a schematic view showing a state after grouting of an anchoring section of a hollow grouting prestressed anchor according to an embodiment of the present invention. Fig. 3 is a schematic view showing a state after secondary grouting of the hollow grouting prestressed anchor according to an embodiment of the present invention. FIG. 4 is a schematic view showing the detailed structure of the anchor head in the hollow grouting prestressed anchor rod according to one embodiment of the present invention.
Referring to fig. 1 to 4, in this embodiment, the hollow grouting prestressed anchor is applied to protection of a foundation pit slope, and includes a hollow rod body 1, an anchor head 2, a nut 3 and a backing plate 4. Wherein, the external diameter of the hollow rod body is 51mm, the internal diameter is 35mm, the length is 8m, and the surface is provided with the external screw thread. The anchoring end of the hollow rod body 1 is conical; the free end of the hollow rod 1 is provided with a polygonal recess 11 along the axial direction for turning the hollow rod by means of a wrench, in this embodiment, the recess 11 is square, and the hollow rod 1 can be turned by means of a square wrench matching the recess 11.
One end of the anchor head 2 is an expansion part 21 consisting of a plurality of spherical shell bodies, and the other end is a cylindrical connecting part 22. One end of the shell is integrally connected with the connecting part 22, and convex teeth are further arranged on the outer surface of the shell to increase the friction force between the expansion part 21 and the inner wall of the anchor rod hole. An internal thread matched with the external thread of the hollow rod body 1 is arranged on the inner wall of the connecting part 22, the length of the internal thread is 1/2-4/5 of the length of the connecting part, the internal thread is arranged on one side far away from the expansion part, and the anchor head 2 is sleeved at the anchoring end of the hollow rod body 1 through the connecting part 22. In addition, the inner diameter of the section without the internal thread of the connecting part 22 is larger than that of the section with the internal thread, a limiting ring 5 is correspondingly fixed at the part of the hollow rod body 1 close to the anchoring end, the limiting ring 5 is welded on the hollow rod body 1, the outer diameter of the limiting ring is slightly smaller than that of the section without the internal thread of the connecting part 22, but the inner diameter of the limiting ring is larger than that of the section with the internal thread of the connecting part 22. Because the anchor head 2 and the hollow rod body 1 are in threaded connection, if the tension is too large in the tensioning process to cause slide fastener to be generated between the anchor head 2 and the hollow rod body 1, the limiting ring 5 can effectively prevent the anchor head 2 from falling off from the anchoring end of the hollow rod body 1.
In this embodiment, the expansion portion 21 is formed by four pieces of spherical shell, one end of which is integrally connected with the end of the connecting portion 22 without internal thread, and the other end of which is in a closed state, and when in use, the hollow rod body 1 penetrates out of the middle of each piece of shell, so that each piece of shell is opened to form the spherical expansion portion 21, thereby increasing the friction force between the expansion portion and the surrounding rock mass.
Specifically, in this embodiment, the length of the connecting portion is 260mm, wherein the length of the section with the internal thread is 180mm, and the length of the section without the internal thread is 80 mm. The spacing ring 5 is arranged 140mm away from the anchoring end of the hollow rod body 1. The four shells of the expansion part 21 can form a hollow sphere with a diameter of about 130mm when opened. When the hollow rod body 1 rotates and moves forwards, because the teeth on the outer surface of the expansion part 21 generate friction with the soil layer or rock stratum in the anchor rod hole 6, the anchor head 2 cannot move forwards along with the hollow rod body 1, and further, the conical anchoring end can extrude and expand the expansion part 21 to form a sphere with the diameter of about 130 mm.
In addition, a pulp outlet 12 is arranged on the hollow rod body at a certain point 1/5-1/2 along the radial direction, and the diameter of the outer side of the pulp outlet 12 is smaller than that of the inner side; go out the downthehole be provided with go out thick liquid hole 12 shape assorted stopple 13, stopple 13 can be made loudspeaker form by soft plastics, folding stopple 13 during the use and fill in from the outside of going out thick liquid hole 12, later stopple 13 can open automatically to block up out thick liquid hole 12, when carrying out the slip casting in the cavity body of rod 1, grout can not flow from this play thick liquid hole. In the anchor rod hole 6, a space between the grout outlet hole 12 and the anchoring end is called an anchoring section, and a space between the grout outlet hole 12 and the free end is called a free section. When the free section is grouted, the hole plug 13 falls off from the grout outlet hole 12 to the inside of the hollow rod body 1 under the action of pressure.
In this embodiment the diameter of the shank bore 6 is 110mm and the anchoring cavity 61 at the bottom of the shank bore 6 is a spherical cavity with a diameter of 150mm for receiving the expansion portion 21 of the anchor head 2. The free end of the hollow rod body 1 is sequentially provided with a reinforced concrete ring beam 7, a pedestal 8, a base plate 4 and a nut 3. The reinforced concrete ring beam 7 can enlarge the stress area of the side slope, and a bracket 9 welded by angle steel is arranged below the reinforced concrete ring beam and used for supporting the ring beam and the pedestal. The pedestal 8 is a wedge-shaped pedestal, and an inclined plane far away from the free end of the pedestal is attached to the ring beam 7; the inclined plane that is close to the free end with backing plate 5 laminating, this inclined plane perpendicular to promptly the cavity body of rod 1 when guaranteeing that the stock carries out stretch-draw, the axial of the cavity body of rod 1 is followed to the effort that nut 3 and backing plate 4 received. Through holes with the same size as the outer diameter of the hollow rod body 1 are arranged on the base plate 4 and the pedestal 8 and are parallel to the hollow rod body; the internal thread of the nut 3 is matched with the external thread of the hollow rod body 1. In addition, the ring beam 7 is provided with a grouting hole 71 leading into the anchor rod hole 6 for grouting free section cement slurry in the anchor rod hole 6.
Example 2
Fig. 5 is a schematic view illustrating a construction process of a hollow grouting prestressed anchor according to an embodiment of the present invention. In this embodiment, a construction process of the hollow grouting prestressed anchor rod described in embodiment 1 is described in detail, and in this embodiment, the hollow grouting prestressed anchor rod is applied to a retaining work of a foundation pit slope.
Referring to fig. 1 to 5, the concrete construction steps of the hollow grouting prestressed anchor rod are as follows:
step S1, firstly, arranging a support 9 at a preset position on the soil body of the foundation pit side slope, manufacturing a reinforced concrete ring beam 7 on the support, reserving a hole position of an anchor rod hole 6 on the ring beam 7, and reserving a grouting hole 71 leading to the anchor rod hole 6 on the ring beam 7. Usually, anchor rods of a plurality of lines and rows are arranged on the side slope of the foundation pit, and the anchor rods with the same height are arranged on the ring beam so as to increase the contact surface of the anchor rods and the side slope. The anchor rod hole site that reserves on the ring roof beam is the same with the inclination in anchor rod hole, the follow-up drilling operation of being convenient for.
And step S2, drilling holes in the anchor rod hole positions according to a preset angle to form anchor rod holes 6. Where the angle of inclination of the bolt hole is to be determined with reference to the construction drawing for the particular project, the bottom of the bolt hole is typically drilled into the rock mass or hard rock. In this embodiment the diameter of the anchor rod eye 6 is 110 mm.
Step S3, the bottom of the anchor rod hole 6 is reamed to form an anchor cavity 61, and then the anchor rod hole and the anchor cavity are cleaned. Reaming may be achieved by installing a reaming bit at the head of the drill rod, the resulting anchoring cavity having an internal dimension greater than the size of the anchor rod bore, in this embodiment a spherical cavity with a diameter of 150 mm. The cleaning work is mainly to clean the residual dregs, broken stones and other impurities in the holes, and if accumulated water exists in the holes, the accumulated water needs to be pumped out.
Step S4, sleeving the anchor head 2 at the anchoring end of the hollow rod body 1 and extending into the anchor rod hole 6 to enable the anchor head 2 to be located in the anchoring cavity 61, and then sequentially installing the wedge-shaped pedestal 8, the backing plate 4 and the nut 3 at the free end of the hollow rod body 1. Because the anchoring end of the hollow rod body 1 is provided with the limiting ring 5, the anchor head 2 can be installed from the free end of the hollow rod body 1 and rotates to the anchoring end along the thread on the hollow rod body, and then the expansion part 21 of the anchor head 2 is folded and gathered together, so that the expansion part 21 is in an unexpanded state and is convenient to insert into the anchor rod hole.
Step S5, fixing the nut 3 so that it cannot rotate, and then rotating the hollow rod 1, or fixing the hollow rod 1 so that it cannot rotate, and then rotating the nut 3, so that the hollow rod 1 moves into the bolt hole. At this time, the teeth on the outer surface of the expansion part 21 generate friction with the rock mass, so that the anchor head cannot rotate along with the hollow rod body 1; thus, the tapered anchoring end of the hollow rod 1 will expand the expansion portion 21 of the anchor head 2 forward, so that the expansion portion 21 will expand, and finally a hollow sphere will be formed, which is not a completely closed sphere, and gaps will be formed between the shells of the expansion portion after the expansion. And stopping rotating the hollow rod body when the end part of the hollow rod body 1 reaches the bottom of the anchoring cavity. And then grouting cement slurry into the anchoring cavity and the bottom of the anchor rod hole through the inner cavity of the hollow rod body 1 until the upper layer of the cement slurry is close to the slurry outlet hole, and stopping grouting to form an anchoring section. At this time, the inside and outside of the expansion part are filled with cement paste. It needs to be noted that, before carrying out the slip casting, if there is ponding in the anchor intracavity, the inner chamber of the accessible cavity body of rod is extracted ponding, reduces the influence of moisture to grout. Before grouting, the volume of cement paste required by an anchoring section needs to be calculated, wherein the volume is the volume from the grout outlet 12 to each cavity at the bottom of the anchor rod hole, and the grout outlet 12 is not covered by grouting. In addition, the early strength agent is added into the cement paste, so that the hardening speed of the cement paste can be increased.
And step S6, after the cement slurry poured into the anchoring section is hardened and the strength reaches a design value, tensioning the anchor rod until the tension reaches the design value. The specific stretching process is to fix the hollow rod body 1 to be incapable of rotating, and then to rotate the nut 3, so that the hollow rod body 1 moves out of the anchor rod hole. An electric tool can be adopted when the nut 3 is rotated, and the rotation can be stopped when the anchor rod reaches the designed tension value. In addition, tensioning equipment (such as an oil pressure gauge, a jack and a force measuring device) can be directly sleeved at the free end of the hollow rod body according to requirements to tension the anchor rod, and when the tension value reaches a designed value, the nut 3 is screwed to lock the hollow rod body and cannot contract inwards any more.
And step S7, injecting cement slurry into the anchor rod hole 6 through the grouting hole 71 reserved on the reinforced concrete ring beam 7 until the cement slurry flows out of the free end of the hollow rod body, and then stopping grouting to form a free section. When the downthehole slip casting of stock, grout gets into in the stock hole from the slip casting of upper end, make the downthehole pressure increase of stock, until will go out the hole stopper 13 on grout hole 12 and impress the inner chamber of cavity stock 1, if there is ponding in the stock hole, then ponding can be discharged from the free end of cavity stock 1 under the downthehole pressure of stock, along with going on of slip casting process, downthehole water of stock and air are discharged gradually, all be full of grout until the stock downthehole and cavity stock intracavity, then stop the slip casting.
And step S8, finally, plugging the grouting hole 71, and sealing the anchor, wherein the redundant hollow rod body at the outside needs to be cut off when the anchor is sealed.
On the slope of the same foundation pit, five groups of hollow grouting prestressed anchor rods are manufactured and installed according to the hollow grouting prestressed anchor rods and the construction method thereof in the embodiments 1 and 2, and the numbers are 1 to 5; in addition, five groups of traditional hollow grouting prestressed anchor rods are manufactured and installed, the number is 6-10, and the type R51/8 hollow grouting anchor rod produced by the oriental. The two are the same in size specification, wherein the length of the hollow rod body is 8m, the outer diameter is 51mm, and the wall thickness is 8 mm; the ultimate tensile value of the hollow rod body is 640KN, the aperture of the anchor rod hole is 110mm, and the designed tensile value is 350 KN. The bottom of the anchor rod hole is weakly weathered bedrock.
The concrete parameters of the cement slurry are as follows:
grouting materials: p.o42.5 portland cement slurry; the cement paste is uniformly stirred by a secondary stirrer.
Proportioning the slurry: cement paste to triethanolamine (early strength agent): 1: 0.5 per mill;
cement paste water cement ratio: 1: 0.55.
Strength of cement paste: m30.
The difference between the two is that the expanding part of the hollow grouting prestressed anchor rod consists of a plurality of spherical shell bodies, an expanded anchoring cavity is arranged at the bottom of an anchor rod hole, a grout outlet hole is arranged in the middle of the hollow rod body, grouting is respectively carried out on an anchoring section and a free section during construction, and the length of the anchoring section is 5 m. The traditional hollow grouting prestressed anchor rod only carries out one-time grouting to ensure that the anchor rod hole and the inner cavity of the hollow rod body are filled with cement slurry.
After the construction is finished, ten groups of anchor rods are respectively tensioned, and the maximum tension value which can be reached by each group of anchor rods is shown in a table 1:
TABLE 1
Anchor rod numbering 1 2 3 4 5 6 7 8 9 10
Maximum tensile force value/KN 467 459 455 456 471 345 351 357 348 346
Referring to the data in table 1, the maximum tensile values that can be achieved by the five groups of hollow grouting prestressed anchor rods of the invention far exceed the designed tensile values, while the maximum tensile values that can be achieved by the five groups of hollow grouting prestressed anchor rods manufactured by the traditional method fluctuate up and down the designed tensile values. Therefore, under the same parameter size, the tension of the hollow grouting prestressed anchor rod can be far greater than that of the traditional anchor rod.
In addition, five groups of hollow grouting prestressed anchor rods are manufactured according to the method provided by the invention, and are numbered from 11 to 15. The difference between the hollow grouting prestressed anchor rod and the hollow grouting prestressed anchor rod with the serial numbers of 1 to 5 is that the length of the hollow rod body is 5.5m, the length of the anchoring section is 4m, and the length of an anchor rod hole is correspondingly reduced. After the construction is finished, the construction is tensioned, and the maximum tension value which can be reached is shown in table 2:
TABLE 2
Anchor rod numbering 11 12 13 14 15
Maximum tensile force value/KN 367 359 355 356 371
Referring to the data in table 2, the length of the hollow grouting prestressed anchor rod of the invention is shortened to a certain extent, and the designed tension value can be achieved. Thereby reducing the cost of the construction work.
A hollow grouting prestressed anchor and a construction method thereof according to the present invention have been described above by way of example with reference to the accompanying drawings. However, it should be understood by those skilled in the art that various modifications may be made to the hollow grouting prestressed anchor and its construction method without departing from the scope of the present invention. Therefore, the scope of the present invention should be determined by the contents of the appended claims.

Claims (8)

1. A hollow grouting prestressed anchor rod comprises a hollow rod body, an anchor head, a nut and a base plate, and is characterized in that,
the surface of the hollow rod body is provided with external threads, the anchor head is arranged at the anchoring end of the hollow rod body, and the nut and the base plate are arranged at the free end of the hollow rod body;
one end of the anchor head is an expansion part consisting of a plurality of spherical-segment-shaped shells, and the other end of the anchor head is a cylindrical connecting part; one end of the shell is integrally connected with the connecting part, and convex teeth are arranged on the outer surface of the shell; the inner wall of connecting portion be provided with external screw thread assorted internal thread, the anchor head passes through connecting portion cup joint is in the tip of the cavity body of rod.
2. The hollow grouting prestressed anchor of claim 1, wherein the anchoring end of the hollow rod body is tapered.
3. The hollow grouting prestressed anchor of claim 1, wherein the connecting portion has no internal thread on a side thereof adjacent to the expansion portion, and has an internal thread on a side thereof remote from the expansion portion, and the connecting portion has no internal thread section having an internal diameter larger than that of the connecting portion having an internal thread section.
4. A hollow grouting prestressed anchor as claimed in claim 3, wherein a stop ring is provided on said hollow shank body near said anchoring end to prevent said anchor head from falling off said anchoring end.
5. The hollow grouting prestressed anchor of claim 1, wherein the free end of the hollow rod body is axially provided with a polygonal groove for engaging a wrench to rotate the hollow rod body.
6. The hollow grouting prestressed anchor of claim 1, wherein a grout outlet is radially provided at a point 1/5 to 1/2 on the hollow rod body, and the diameter of the outer side of the grout outlet is smaller than that of the inner side; and a hole plug matched with the shape of the slurry outlet hole is arranged in the slurry outlet hole.
7. A method for constructing a hollow grouting prestressed anchor, which adopts the hollow grouting prestressed anchor as claimed in any one of claims 1 to 6, and comprises the following steps:
s1, manufacturing a reinforced concrete ring beam at a preset position of a soil body, reserving an anchor rod hole position on the ring beam, and reserving a grouting hole leading to the anchor rod hole on the ring beam;
s2, drilling holes in the anchor rod hole sites according to a preset angle to form anchor rod holes;
s3, reaming the bottom of the anchor rod hole to form an anchoring cavity, and then cleaning the anchor rod hole and the anchoring cavity;
s4, sleeving the anchor head at the anchoring end of the hollow rod body and extending into the anchor rod hole to enable the anchor head to be located in the anchoring cavity, and sequentially installing a pedestal, a backing plate and a nut at the free end of the hollow rod body;
s5, rotating the hollow rod body to enable the expansion part of the anchor head to expand under squeezing and expanding of the hollow rod body, then pouring cement slurry into the anchoring cavity and the bottom of the anchor rod hole through the inner cavity of the hollow rod body until the upper layer of the cement slurry is close to the slurry outlet hole, and stopping grouting to form an anchoring section;
s6, after the cement strength of the anchoring section reaches a design value, tensioning the anchor rod until the tension reaches the design value;
s7, injecting cement slurry into the anchor rod hole through the grouting hole until the cement slurry flows out of the free end of the hollow rod body, and then stopping grouting to form a free section;
and S8, plugging the grouting hole, and then sealing the anchor.
8. The method as claimed in claim 7, wherein one inclined surface of the platform is engaged with the ring beam, and the other inclined surface of the platform is perpendicular to the anchor.
CN201910845916.XA 2019-09-09 2019-09-09 Hollow grouting prestressed anchor rod and construction method thereof Active CN110670599B (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112144526A (en) * 2020-09-15 2020-12-29 河北建筑工程学院 Double-cavity anchor rod structure for improving soil condition

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