Rotary jet grouting drill rod for reinforcing high-pressure jet expanded-head anchor rod

Abstract

The rotary jet drill rod comprises a rod body and a hollow drill bit installed at the lower end of the rod body, the rod body is of a double-rod structure and comprises an inner pipe and an outer pipe arranged on the outer side of the inner pipe in a sleeving mode, an inner cavity of the inner pipe is a water cavity, and a slurry cavity is formed between the inner pipe and the outer pipe; the inner pipe and the outer pipe are detachably mounted on the hollow drill bit; a through-hole-shaped spraying hole is formed in the lower end of the rotary spraying drill rod, the spraying hole penetrates through the peripheral surface of the rotary spraying drill rod, the slurry cavity is communicated with the spraying hole, and cement slurry in the slurry cavity can be sprayed out through the spraying hole; the water cavity communicates with an inner cavity of the hollow drill bit. By means of the method, a cement-soil inclusion can be formed on the existing high-pressure injection expanded-head anchor rod again, the connecting strength of a post-construction reinforcing part and the existing high-pressure injection expanded-head anchor rod is improved, and due to the fact that reinforcement and reinforcement of the single high-pressure injection expanded-head anchor rod can be completed at a time, the construction efficiency is improved, and the construction cost is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of for high-pressure jetting enlarged head anchor rod reinforcement and reinforcement of rotary jetting drill rod. BACKGROUND

[0002] High-pressure jetting enlarged head anchor rod is that high-pressure fluid is used to cut and expand hole and grout cement slurry or cement mortar to the soil in the bottom of anchor hole according to design length, and form the anchor rod of the cylindrical grouting body with larger diameter.The Chinese industry standard "high-pressure jetting enlarged head anchor rod technical specification" (JGJ / T282-2012) stipulates that the compressive strength of anchor section grouting body should not be less than 20MPa in general.High-pressure jetting enlarged head anchor rod is based on ordinary anchor rod, and the soil outside the anchor hole in a certain length range at the bottom of anchor hole is cut and expanded by high-pressure jetting with water and cement slurry or cement mortar, and cement slurry is grouted in the anchor hole to form the anchor rod of cylindrical cement-soil anchoring body with larger diameter.The process requires pre-emptying hole, and then injecting pure cement slurry or cement mortar, which is easy to collapse hole in soft soil foundation, especially in inclined hole construction, resulting in insufficient bearing capacity of high-pressure jetting enlarged head anchor rod and unable to meet the design requirements.Therefore, when the bearing capacity of high-pressure jetting enlarged head anchor rod is insufficient, it is common to supplement pile around the existing high-pressure jetting enlarged head anchor rod, abandon the existing high-pressure jetting enlarged head anchor rod or use it together with the existing high-pressure jetting enlarged head anchor rod, but this construction method may result in that the later-constructed high-pressure jetting enlarged head anchor rod also cannot meet the design requirements, and supplementing pile requires adjusting the corresponding frame structure, which increases construction cost, so the best solution is to reinforce and strengthen the existing high-pressure jetting enlarged head anchor rod, but the existing reinforcement and strengthening is generally to directly construct rotary jetting pile on one side of the existing high-pressure jetting enlarged head anchor rod, and to improve frictional resistance by using the later-constructed rotary jetting pile, which is difficult to position the already-constructed high-pressure jetting enlarged head anchor rod, and the new rotary jetting pile cannot bond with the existing high-pressure jetting enlarged head anchor rod with weak bonding strength, and in order to evenly bear stress, at least three rotary jetting piles are usually constructed around the existing high-pressure jetting enlarged head anchor rod, which undoubtedly increases construction amount and construction cost, so how to low-cost reinforce and strengthen the existing high-pressure jetting enlarged head anchor rod still has strong practical significance. SUMMARY

[0003] In order to reduce the construction cost of reinforcement and improve the connection strength between the post-construction reinforcement part and the existing high-pressure jet expansion head anchor rod, the application provides a rotary jet drill rod for reinforcing and strengthening a high-pressure jet expansion head anchor rod, which comprises a rod body and a hollow drill bit mounted at the lower end of the rod body. The rod body is a double rod structure, and comprises an inner tube and an outer tube sleeved outside the inner tube. The inner cavity of the inner tube is a water cavity, and a slurry cavity is formed between the inner tube and the outer tube. The inner tube and the outer tube are detachably mounted on the hollow drill bit. A jet hole in the form of a through hole is arranged at the lower end of the rotary jet drill rod, and the jet hole penetrates the outer peripheral surface of the rotary jet drill rod. The slurry cavity is communicated with the jet hole, and the cement slurry in the slurry cavity can be sprayed outward through the jet hole. The water cavity is communicated with the inner cavity of the hollow drill bit, and the inner cavity of the hollow drill bit penetrates the lower end surface of the hollow drill bit downward.

[0004] When the rotary jet drill rod is used to reinforce and strengthen the high-pressure jet expansion head anchor rod, the steps are as follows:

[0005] (1) Rotate the rotary jet drill rod, drill the rotary jet drill rod along the axial direction of the high-pressure jet expansion head anchor rod, and drill the rotary jet drill rod into the ground until the hollow drill bit of the rotary jet drill rod reaches the set depth. When the rotary jet drill rod is drilled into the ground, the hollow drill bit cuts the soil around the high-pressure jet expansion head anchor rod and forms a core rod. The rod body of the high-pressure jet expansion head anchor rod is located in the core rod, and the rotary jet drill rod is sleeved on the core rod. The annular gap between the inner wall of the hollow drill bit and the core rod forms a ring-shaped jet port, and high-pressure water is sprayed downward through the jet port to impact the soil. The rotary jet drill rod and the high-pressure jet expansion head anchor rod are coaxially arranged.

[0006] (2) Rotate the rotary jet drill rod, spray cement slurry around the core rod, and form a cement-soil wrapping body. The cement-soil wrapping body is located on the upper side of the stiffened expansion head of the high-pressure jet expansion head anchor rod, and the cement-soil wrapping body is wrapped on the core rod. The outer diameter of the cement-soil wrapping body is greater than the outer diameter of the stiffened expansion head. The stiffened expansion head of the high-pressure jet expansion head anchor rod can be a steel cage expansion head or a bag-type expansion head.

[0007] The spraying pressure of the cement slurry is 20.0-30.0 MPa, and the pressure of the high-pressure water is 0.2-3.0 MP. The outer diameter of the formed cement-soil wrapping body is 1.2-2 times the outer diameter of the stiffened expansion head of the high-pressure jet expansion head anchor rod. The contact area between the reinforced high-pressure jet expansion head anchor rod and the underground soil can be effectively expanded, so as to improve the friction resistance of the high-pressure jet expansion head anchor rod. The formed cement-soil wrapping body is connected with the stiffened expansion head of the high-pressure jet expansion head anchor rod. The newly constructed cement-soil wrapping body and the stiffened expansion head form an integral whole and jointly resist the external force transmitted by the rod body. Preferably, the cement-soil wrapping body extends upward to the top of the high-pressure jet expansion head anchor rod, so as to fully improve the friction resistance of the high-pressure jet expansion head anchor rod. When the cement-soil wrapping body is formed, the rotary jet drill rod can be reciprocated along the axial direction for multiple times.

[0008] The rod body of the high-pressure jet expanding head anchor pile can be made of finish-rolled threaded steel, prestressed steel strand or carbon fiber cable. When the rod body is made of multiple prestressed steel strands or carbon fiber cables, each prestressed steel strand or carbon fiber cable is referred to as a rod body in the present application.

[0009] The existing high-pressure jet expanding head anchor pile can be reformed with the rotary jet drill rod in the present application to form a cement-soil wrapping body. The cement-soil wrapping body as a post-construction reinforcement part can improve the frictional resistance of the high-pressure jet expanding head anchor pile. Since the cement-soil wrapping body is wrapped around the core rod, the cement-soil wrapping body formed by post-construction and the existing structure of the high-pressure jet expanding head anchor pile can form an integral whole, avoiding the problem of low bonding strength between the post-construction rotary jet pile and the existing high-pressure jet expanding head anchor pile in the prior art. Moreover, the cement-soil wrapping body is wrapped around the core rod and has at most only a small amount of eccentricity, so it is only necessary to set the size of the cement-soil wrapping body according to the strength of the existing high-pressure jet expanding head anchor pile. The reinforcement and strengthening of a single high-pressure jet expanding head anchor pile can be completed at one time, providing construction efficiency and reducing construction cost. Thus, the problem of high construction efficiency and construction cost caused by the need to construct multiple rotary jet piles around the existing high-pressure jet expanding head anchor pile in the prior art is avoided.

[0010] Further, the inner tube, the outer tube and the hollow drill bit are coaxially arranged.

[0011] Specifically, the hollow drill bit includes a ring body in the shape of a circular ring, an inner tangent tube and an outer tangent tube extending upward in the axial direction are arranged on the upper side of the ring body, a jetting cavity with an upward opening is formed between the inner tangent tube and the outer tangent tube, a jetting hole is arranged on the outer tangent tube, the inner tube is screwed on the inner tangent tube, and the outer tube is screwed on the outer tangent tube.

[0012] The hollow drill bit can be produced by one-time forming, or the inner tangent tube, the outer tangent tube and the ring body can be separately processed and then welded together. The inner tube and the outer tube are connected together by the hollow drill bit to simplify the structure of the drill rod. Preferably, teeth are arranged at the lower end of the ring body to improve the cutting efficiency.

[0013] Further, the outer wall of the outer tube does not exceed the outer wall of the hollow drill bit. This design can avoid unnecessary excessive wear of the outer tube to improve the service life of the outer tube.

[0014] Further, the inner diameter of the inner tube is larger than the inner diameter of the hollow drill bit. When the inner diameter of the inner tube is the same as the inner diameter of the hollow drill bit, the wear of the inner wall of the inner tube is approximately the same as the wear of the inner wall of the hollow drill bit, but as the rotary jet drill rod drills into the ground, the length of the core rod entering the inner tube becomes larger and larger, and the narrow gap between the core rod and the inner tube can cause the high-pressure water to be unable to be sprayed downward. When the inner diameter of the inner tube is larger than the inner diameter of the hollow drill bit, a larger annular gap can be formed between the core rod and the inner tube to reduce the pressure loss of the high-pressure water, thereby reducing the pressure required by the high-pressure water. This design can reduce the wear of the inner tube and improve the service life of the inner tube. Specifically, the inner diameter of the inner tube is 2-20 mm larger than the inner diameter of the hollow drill bit.

[0015] Further, to avoid damage to the rod body in the high-pressure jet expansion head anchor rod, the inner diameter of the hollow drill bit is 5-20 mm larger than the outer diameter of the ordinary anchoring section of the high-pressure jet expansion head anchor rod; and when the rotary jet drill rod drills into the ground along the axial direction of the high-pressure jet expansion head anchor rod, the rotary jet drill rod is coaxially arranged with the high-pressure jet expansion head anchor rod, and the inner wall of the hollow drill bit is at least 10 mm away from the outer wall of any rod body of the high-pressure jet expansion head anchor rod. Under the above limitations, the rotary jet drill rod mainly cuts the soil around the high-pressure jet expansion head anchor rod, and even if there is an error in construction, the rotary jet drill rod will only cut the edge of the cement-soil shell of the high-pressure jet expansion head anchor rod and will not touch the rod body. When the rod body is composed of a plurality of prestressed steel strands or carbon fiber cables, each prestressed steel strand or carbon fiber cable is referred to as a rod body in this application. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a structural schematic diagram of an embodiment of the rotary jet drill rod.

[0017] Figure 2 is a structural schematic diagram of an embodiment of the rotary jet drill rod. Figure 1 is an enlarged view of part A in

[0018] Figure 3 is an exploded view of Figure 2

[0019] Figure 4 is a structural schematic diagram of the high-pressure jet expansion head anchor rod.

[0020] Figure 5 is a state diagram when the pile machine is in place.

[0021] Figure 6 is an enlarged view of part B in Figure 5

[0022] Figure 7 is a state diagram when the drill rod completes drilling.

[0023] Figure 8 is a state diagram when the drill rod completes drilling. Figure 7 ​​Enlarged view of the middle C portion.

[0024] Figure 9 is a state diagram when the reinforcement is completed. DETAILED DESCRIPTION

[0025] The structure of the high-pressure jet expansion head anchor rod 30 reinforced by the present application will be described first as follows, please refer to Figure 4 The steel structure of the high-pressure jet expansion head anchor rod 30 includes a rod body 31 and an expansion head reinforcement cage 36 fixedly connected to the lower end of the rod body 31, the expansion head reinforcement cage 36 and the surrounding cement-soil block 37 together form a reinforcement cage expansion head, the rod body 31 extends upward along the axis of the high-pressure jet expansion head anchor rod out of the ground 100, and the surrounding of the rod body 31 has a cement-soil shell 34 formed by cement-soil. Along the axial direction of the high-pressure jet expansion head anchor rod, the high-pressure jet expansion head anchor rod is sequentially divided into an expansion head section S, a common anchoring section M and a free section N from bottom to top, the reinforcement cage expansion head is formed into the expansion head section S, the expansion head section S and the common anchoring section M together form an anchoring section, and the common anchoring section and the free section have the same outer diameter. In this embodiment, each high-pressure jet expansion head anchor rod is provided with four steel strands, the four steel strands are dispersedly arranged, each steel strand is formed into a rod body, and a plastic sleeve 33 is sleeved on the free section area of each steel strand. The centering support 32 on the rod body 31 is a plastic part. It can be understood that in other embodiments, the rod body can also be a carbon fiber cable or a finished threaded steel bar.

[0026] The structure of the rotary jet drill rod will be described as follows, please refer to Figures 1-3 The rotary jet drill rod specifically includes a rod body 10 and a hollow drill bit 20 installed at the lower end of the rod body, the rod body 10 is a double rod structure, and the rod body includes an inner tube 11 and an outer tube 12 sleeved on the outer side of the inner tube, the inner cavity of the inner tube is a water cavity 13, and a slurry cavity 14 is formed between the inner tube and the outer tube. The inner tube, the outer tube and the hollow drill bit are coaxially arranged.

[0027] The hollow drill bit 20 includes a ring body 21 in the shape of a circular ring, and has a central hole 26 extending along the axial direction and penetrating through both ends of the ring body 21, the central hole is the inner cavity of the hollow drill bit, so that the inner cavity of the hollow drill bit penetrates through the lower end surface of the hollow drill bit downward. An inner tangent pipe 22 and an outer tangent pipe 23 extending upward along the axial direction are arranged on the upper side of the ring body, a jet cavity 24 open upward is formed between the inner tangent pipe and the outer tangent pipe, the outer tangent pipe is located on the outer side of the inner tangent pipe, a jet hole 25 is arranged on the outer tangent pipe and penetrates through the outer wall of the outer tangent pipe outward, in the axial direction, the top end of the inner tangent pipe is lower than the top end of the outer tangent pipe, and the jet hole is located within the height range of the inner tangent pipe. The slurry cavity is communicated with the jet hole, and the cement slurry in the slurry cavity can be sprayed outward through the jet hole. The ring body is provided with a tooth 27 at the lower end.

[0028] The inner thread is arranged on the inner wall of the inner sleeve and the outer sleeve, and the outer thread is arranged on the outer wall of the lower end of the inner sleeve and the outer sleeve. The inner sleeve is screwed on the inner side of the inner sleeve, and the outer sleeve is screwed on the outer side of the outer sleeve, so that the center hole 26 of the hollow drill bit is connected to the water cavity 13 of the inner sleeve. In this embodiment, the inner sleeve and the outer sleeve are integrally formed with the ring body. It can be understood that in another embodiment, the inner sleeve, the outer sleeve and the ring body can also be separately processed, and then the inner sleeve and the outer sleeve are welded on the ring body.

[0029] To avoid excessive wear on the outer sleeve, the outer wall of the outer sleeve does not exceed the outer wall of the hollow drill bit. Specifically, in this embodiment, the outer diameter of the outer sleeve is the same as the outer diameter of the hollow drill bit. In this embodiment, the inner diameter of the inner sleeve is 10mm larger than the inner diameter of the center hole. It can be understood that in other embodiments, the inner diameter of the inner sleeve can also be 2mm, 5mm, 15mm, 20mm or other data between 2-20mm larger than the inner diameter of the center hole.

[0030] In this embodiment, the inner diameter of the hollow drill bit is 10mm larger than the outer diameter of the ordinary anchoring section of the high-pressure jet expansion head anchor rod, and when the rotary jet drill rod is drilled into the ground along the axis of the high-pressure jet expansion head anchor rod, the rotary jet drill rod is coaxially arranged with the high-pressure jet expansion head anchor rod, and the inner wall of the hollow drill bit has a distance of at least 10mm from the outer wall of any rod body of the high-pressure jet expansion head anchor rod. It can be understood that in other embodiments, the inner diameter of the hollow drill bit can also be 5mm, 15mm or 20mm larger than the outer diameter of the ordinary anchoring section, or other distances between 5-20mm.

[0031] The following describes the construction method of reinforcing the existing high-pressure jet expansion head anchor rod with the rotary jet drill rod. Please refer to Figures 5-9 , the construction method comprises the following steps:

[0032] (1) Install the rotary jet drill rod on the rotary jet drill machine 40, rotate the rotary jet drill rod, and drill the rotary jet drill rod into the ground along the axis of the high-pressure jet expansion head anchor rod 30 until the hollow drill bit of the rotary jet drill rod reaches the set depth. In this embodiment, the set depth is the upper end surface of the reinforcement cage expansion head. When the rotary jet drill rod is drilled into the ground, the hollow drill bit cuts the soil around the high-pressure jet expansion head anchor rod and forms a core rod 35, all rod bodies are located in the core rod, and the rotary jet drill rod is sleeved on the core rod. The rotary jet drill rod is coaxially arranged with the high-pressure jet expansion head anchor rod.

[0033] The annular gap between the inner wall of the hollow drill bit and the core rod forms a ring-shaped jet port. When the jetting drill rod is drilled downward, high-pressure water enters the water cavity 13 through the first external pipe 61 and is sprayed downward through the jet port, thereby breaking the soil and cooling the hollow drill bit. In this embodiment, the pressure of the high-pressure water is 0.5-1.0 MPa. It can be understood that in other embodiments, the pressure of the high-pressure water can also be other pressure values or pressure intervals between 0.2-3.0 MPa.

[0034] When the jetting drill rod is drilled downward along the axial direction of the high-pressure jetting expansion head anchor rod, the inner wall of the hollow drill bit and the outer wall of any rod body of the high-pressure jetting expansion head anchor rod have a distance of at least not less than 10 mm.

[0035] (2) Rotate the jetting drill rod and lift it upward. The cement slurry enters the slurry cavity 14 through the second external pipe 62 and then enters the jetting cavity 24. The cement slurry in the jetting cavity 24 is sprayed around the core rod through the jetting hole 25, forming a cement-soil wrapping body 51 wrapped around the core rod. The jetting pressure of the cement slurry is 25.0-27.0 MPa. It can be understood that the pressure of the cement slurry can also be other pressure values or pressure intervals between 20-30 MPa. When the cement slurry is sprayed, the jetting drill rod remains rotating. According to the needs, the jetting drill rod can be reciprocated along the axial direction multiple times.

[0036] The cement-soil wrapping body 51 is located on the upper side of the reinforced cage expansion head and is bonded to the reinforced cage expansion head. The cement-soil wrapping body extends upward to the top of the high-pressure jetting expansion head anchor rod. In this embodiment, the outer diameter of the cement-soil wrapping body is 1.4 times the outer diameter of the reinforced cage expansion head. It can be understood that in other embodiments, the outer diameter of the cement-soil wrapping body can also be 1.2 times, 1.6 times or 2 times the outer diameter of the reinforced cage expansion head, or other multiples between 1.2-2 times.

[0037] In this embodiment, the reinforced expansion head is a reinforced cage expansion head. It can be understood that in another embodiment, the reinforced expansion head can also be a bag-type expansion head.

Claims

1. A jetting drill rod for high pressure jetting enlargement of a head anchor rod reinforcement, characterized in that, The rotary jetting drill rod comprises a rod body and a hollow drill bit mounted at the lower end of the rod body, the rod body is a double rod structure, the rod body comprises an inner tube and an outer tube sleeved outside the inner tube, the inner cavity of the inner tube is a water cavity, and a slurry cavity is formed between the inner tube and the outer tube; the inner tube and the outer tube are detachably mounted on the hollow drill bit; a jetting hole in the form of a through hole is arranged at the lower end of the rotary jetting drill rod, the jetting hole penetrates the outer peripheral surface of the rotary jetting drill rod, the slurry cavity is communicated with the jetting hole, and the cement slurry in the slurry cavity can be jetted outwards through the jetting hole; the water cavity is communicated with the inner cavity of the hollow drill bit, and the inner cavity of the hollow drill bit penetrates the lower end surface of the hollow drill bit downwards.

2. The jetting drill pipe of claim 1, wherein, The inner tube, the outer tube and the hollow drill bit are coaxially arranged.

3. The jetting drill pipe of claim 1, wherein, The hollow drill bit comprises a ring body in the form of a circular ring, an inner tangent tube and an outer tangent tube extending upwards in the axial direction are arranged on the upper side of the ring body, a jetting cavity with an upward opening is formed between the inner tangent tube and the outer tangent tube, the jetting hole is arranged on the outer tangent tube, the inner tube is screwed on the inner tangent tube, and the outer tube is screwed on the outer tangent tube.

4. The jetting drill pipe of claim 1, wherein, The outer wall of the outer tube does not outwardly exceed the outer wall of the hollow drill bit.

5. The jetting drill pipe of claim 1, wherein, The inner diameter of the inner tube is greater than the inner diameter of the hollow drill bit.

6. The jetting drill pipe of claim 1, wherein, The inner diameter of the inner tube is greater than the inner diameter of the hollow drill bit by 2-20 mm.

7. The jetting drill pipe of claim 1, wherein, The inner diameter of the hollow drill bit is greater than the outer diameter of the ordinary anchoring section of the high-pressure jetting expansion head anchor rod by 5-20 mm; and when the rotary jetting drill rod is drilled downwards along the high-pressure jetting expansion head anchor rod in the axial direction, the rotary jetting drill rod and the high-pressure jetting expansion head anchor rod are coaxially arranged, and the distance between the inner wall of the hollow drill bit and the outer wall of any rod body of the high-pressure jetting expansion head anchor rod is at least not less than 10 mm.

Images