Bag type expanded head anchor rod structure and construction method thereof

Abstract

The invention discloses a bag type expanded head anchor rod structure which comprises an anchor rod assembly in an anchor rod hole and cement soil wrapping the anchor rod assembly, the anchor rod hole is formed through a rotary jet grouting technology, the anchor rod assembly comprises an anchor cable set and a bag, the anchor cable set comprises a plurality of anchor cables, the anti-pulling ends of the anchor cables are located in an expanded head containing cavity of the anchor rod hole, and the bag is arranged in the expanded head containing cavity of the anchor rod hole. The tensioning end extends out of the anchor rod hole, the bag is fixed to the anti-pulling end and located in an expansion head containing cavity of the anchor rod hole, and an anchoring block formed by cement paste is arranged in the bag. The invention further discloses a construction method of the bag type expanded head anchor rod structure. The anchor rod hole is prevented from collapsing through the supporting force of the cement soil in the anchor rod hole, the soil body is compacted through outward permeation of cement paste, the strength of the soil body is improved, and collapse of the anchor rod hole is avoided. And cement soil is utilized to form a cement soil shell for bonding an external soil body and the bag around the bag, so that the friction force between the bag type expansion head and the underground soil body is improved, and the uplift bearing capacity of the anchor rod structure is improved.

Description

Technical Field

[0001] The invention relates to a bladder-type enlarged head anchor rod structure and a construction method thereof. Background Art

[0002] As a deformation technology of the enlarged head anchor, the bladder-type enlarged head anchor structure has been promoted and used because the shape of the enlarged head can be effectively controlled. When constructing the bladder-type enlarged head anchor structure, it is necessary to first dry-drill a hole, then send the rod carrying the bladder bag into the anchor hole, and then grout into the bladder bag to form an enlarged head. However, when constructing the anchor hole, since the soil in the enlarged head cavity cannot be completely taken out, part of the soil remains in the enlarged head cavity, especially when constructing in areas with soft soil, the hole collapse phenomenon often occurs, the bladder structure is difficult to push in, and more soil remains in the enlarged head cavity, so that when grouting into the bladder bag, the bladder bag cannot be fully opened, which affects the outer diameter of the bladder-type enlarged head, resulting in a reduction in the pull-out bearing capacity of the bladder-type enlarged head anchor.

[0003] Since the friction and adhesion between the bladder and the underground soil are relatively small, the anchor rod mainly relies on the end surface resistance of the bladder-type enlarged head to improve the pull-out bearing capacity, which limits the scope of use of the bladder-type enlarged head anchor rod structure. Summary of the invention

[0004] In order to at least partially solve the above-mentioned problems in the prior art, the present application first proposes a bladder-type enlarged head anchor rod structure, which includes an anchor rod assembly inserted into the anchor rod hole and cement soil wrapped on the anchor rod assembly. The anchor rod hole is formed by a rotary spraying process. The anchor rod assembly includes an anchor cable group and a bladder bag. The anchor cable group includes a plurality of anchor cables. The pull-out end of each anchor cable is located in the enlarged head cavity of the anchor rod hole, and the tensioning end of each anchor cable extends outward from the anchor rod hole. The bladder is fixed to the pull-out end and is located in the enlarged head cavity of the anchor rod hole. There is an anchor block formed by cement slurry in the bladder bag.

[0005] In the present application, the anchor hole is constructed by the rotary spraying method, and the cement soil formed by the mixture of cement slurry and soil is retained in the anchor hole. The supporting force of the cement soil is used to avoid the collapse of the anchor hole. In addition, when constructing the anchor hole, the cement slurry will penetrate into the soil around the anchor hole to compact the soil, improve the strength of the soil around the anchor hole, and effectively avoid the collapse of the anchor hole. When the cement slurry is injected into the bag to form the anchor block, it is necessary to complete it before the cement soil in the anchor hole is initially set, so as to utilize the fluidity of the cement soil. The cement soil in the anchor hole can form a cement soil shell around the bag to bond the external soil and the bag. The shell can improve the connection strength between the bag and the underground soil, thereby improving the friction between the bag-type enlarged head and the underground soil, and improving the pull-out bearing capacity of the anchor structure, avoiding the defect that the friction between the bag-type enlarged head and the underground soil is small in the prior art, and the pull-out bearing capacity is mainly improved by the end resistance of the bag-type enlarged head.

[0006] Specifically, two anchor disc assemblies are fixedly installed on the anchor cable group, and the two anchor disc assemblies are respectively a first anchor disc assembly and a second anchor disc assembly, wherein the second anchor disc assembly is located on the side of the first anchor disc assembly away from the tensioning end, and the end of the bag facing the tensioning end is sealed and fixed on the first anchor disc assembly; a grouting pipe hole and an exhaust pipe hole are opened on the first anchor disc assembly, wherein the grouting pipe hole is used to insert the grouting pipe, and the exhaust pipe hole is used to insert the exhaust pipe, when one end of the grouting pipe and the exhaust pipe are respectively inserted into the grouting pipe hole and the exhaust pipe hole, the other ends of the grouting pipe and the exhaust pipe both extend outward from the anchor rod hole; a center hole is provided on the first anchor disc assembly, and the rotary jet drill rod can pass through the center hole in a sealed manner and then press against the second anchor disc assembly to send the anchor rod assembly into the anchor rod hole. Preferably, a sealing ring is provided between the inner wall of the center hole of the first anchor disc assembly and the rotary jet drill rod to seal the gap between the rotary jet drill rod and the inner wall of the center hole. Both the grouting pipe and the exhaust pipe can be inserted into the bag, wherein the grouting pipe is used to inject cement slurry into the bag, and the exhaust pipe is used to discharge the gas in the bag to the outside during grouting to avoid difficulties in grouting into the bag due to obstruction of cement soil in the anchor hole.

[0007] In order to improve the sealing performance, it is preferred to sleeve a sealing ring between the grouting pipe and the grouting pipe hole, and to sleeve a sealing ring between the exhaust pipe and the exhaust pipe hole.

[0008] Two anchor plate assemblies are used to improve the connection strength between the anchor assembly and the anchor block in the bag, and the exhaust pipe is used to facilitate the grouting of the bag. In this application, the anchor hole is formed by the rotary spraying process, and there is cement soil formed by mixing cement slurry and soil in the anchor hole, which has a strong sealing performance. If the grouting pipe is used to grout the bag, the air in the bag cannot be discharged smoothly, and the bag may not be fully opened, thereby affecting the outer diameter of the bladder expansion head.

[0009] Further, one end of the bladder away from the tensioning end is sealingly fixed to the second anchor plate assembly, and the second anchor plate assembly closes the end of the bladder away from the tensioning end; or one end of the bladder away from the tensioning end is sealingly fixed to the second anchor plate assembly, a guide cap is fixedly installed on the side of the second anchor plate assembly away from the tensioning end, and a slurry hole connecting the guide cap and the bladder is provided on the second anchor plate assembly, and the guide cap and the second anchor plate assembly jointly close the end of the bladder away from the tensioning end.

[0010] In specific construction, the guide cap can be set or cancelled as needed. In this design, when the guide cap is not set, the anchor assembly needs to use the second anchor plate assembly to overcome the resistance of cement soil in the anchor hole during the insertion of the anchor assembly into the anchor hole. The resistance will be slightly greater than when the guide cap is set, but some structural parts will be reduced.

[0011] Furthermore, the end of the bag away from the tensioning end is a closed end, and the second anchor plate assembly is located in the bag. In this design, the bag is a bag with one end open, which is more convenient to install. During the specific construction, a guide cap can be installed on the side of the second anchor plate assembly away from the first anchor plate assembly. When the anchor rod assembly is sent into the anchor rod hole, the bag will fit on the guide piece to reduce the pushing resistance of the anchor rod assembly.

[0012] Specifically, in order to keep each anchor plate assembly stably on the anchor cable and avoid damage to the anchor cable, each anchor plate assembly includes an anchor plate and an extrusion plate. Corresponding to each anchor cable, an anchor hole in the form of a through hole is provided on the anchor plate. The end of the anchor hole away from the tensioning end is formed into a conical hole with the small end facing the tensioning end. A clip group is arranged in the conical hole. The extrusion plate is located on the side of the anchor plate away from the tensioning end. The locking bolt connects the extrusion plate to the anchor plate, and the extrusion plate tightly squeezes the clips in the clip group into the conical hole to fix the anchor cable on the anchor plate. The clip-type anchor is a conventional anchor for the anchor cable, which can avoid installing the anchor plate assembly by welding or other methods that affect the strength of the anchor cable.

[0013] Furthermore, a cement soil enlarged head is provided on the side of the bladder bag facing the tensioning end, and the diameter of the cement soil enlarged head is larger than the diameter of the free section. In the process of forming the cement soil enlarged head, cement slurry will diffuse outward in the surrounding soil, thereby improving the connection strength between the cement soil enlarged head and the underground soil, thereby improving the stability of the cement soil enlarged head underground. The cement soil enlarged head and the bladder-type enlarged head together form an enlarged head section of the anchor rod structure, enhancing the stability of the bladder-type enlarged head underground and improving the use range of the bladder-type enlarged head. The outer diameter of the cement soil enlarged head is 0.8-1.2 times the outer diameter of the anchor block, and preferably the outer diameter of the cement soil enlarged head is the same as the outer diameter of the anchor block.

[0014] Secondly, the present application also discloses a construction method of the bladder-type enlarged head anchor structure described in any one of the above items, which comprises the following steps:

[0015] (1) drilling an anchor hole using a jet grouting drill rod and forming an enlarged head cavity at a set position; when drilling the anchor hole, spraying a first cement slurry outward through the jet grouting drill rod, and the first cement slurry forms cement soil with the soil;

[0016] (2) inserting the anchor assembly carrying the grouting pipe and the exhaust pipe into the anchor hole by using the jet jet drill rod, and positioning the bag in the enlarged head cavity;

[0017] (3) injecting the second cement slurry into the bladder bag through the grouting pipe to form a bladder-type enlarged head, and the air in the bladder bag is discharged outward through the exhaust pipe; during the process of injecting the second cement slurry into the bladder bag, the jet grouting drill rod needs to be always inserted in the center hole of the first anchor plate assembly to ensure the grouting pressure in the bladder bag;

[0018] (4) injecting the third cement slurry into the common anchoring section and the free section;

[0019] (5) When the slurry in the anchor hole solidifies and reaches the set strength, the anchor cable is tensioned and locked.

[0020] The jet-jet drill rod keeps rotating during the process of inserting the rod assembly into the anchor hole.

[0021] In this construction method, cement soil is used to support the anchor hole, thereby avoiding the collapse of the inner wall of the anchor hole. Since cement soil has strong fluidity, when the second cement slurry is injected into the bag, the bag can be expanded, and under the squeezing of the bag, part of the cement soil in the anchor hole will flow out of the anchor hole. In order to avoid the cement soil in the anchor hole solidifying, resulting in the failure of grouting in the bag, it is necessary to complete the grouting of the bag before the cement soil completes the initial setting. Step (4) The injection of the third cement slurry into the ordinary anchor section and the free section is a secondary grouting of the ordinary anchor section and the free section to improve the density of the cement soil in the ordinary anchor section and the free section.

[0022] In the existing construction, the anchor assembly is manually pushed into the anchor hole using fine-rolled threaded steel bars, which is a static press-in method. Since the fine-rolled threaded steel bars are slender and have a small pushing force, if there is a lot of crushed soil remaining in the anchor hole, it cannot be pushed in. The anchor assembly can only be pulled out and the anchor hole must be cleaned again. During the construction, the hole may collapse during the cleaning process, and repeated cleaning is often required to insert the anchor assembly to the set depth.

[0023] In the present application, the anchor assembly is inserted into the anchor hole by using a jet grouting drill rod, which has a large thrust and can overcome the resistance of cement soil in the anchor hole. In addition, when the jet grouting drill rod pushes the anchor assembly forward, it needs to keep rotating all the time, so the anchor assembly has a good positioning ability.

[0024] Specifically, in order to smoothly complete the construction of the anchor hole and complete the secondary grouting of the common anchor section and the free section, in step (1), when drilling the anchor hole, first use a grouting pressure of 10-15MPa to form the hole, and then use a grouting pressure of 25-35MPa to form the enlarged head cavity; the water-cement ratio of the first cement slurry is 1.0-1.5; in step (4), the grouting pressure in the common anchor section and the free section is 10-15MPa, and the water-cement ratio of the third cement slurry is 1.0-1.5. In this application, the water-cement ratio of each cement slurry is the weight ratio of water to cement.

[0025] Specifically, to ensure the strength of the anchor block, in step (3), when the second cement slurry is injected into the bladder bag, the grouting pressure is 4-8MPa, and the water-cement ratio of the second cement slurry is 0.4-0.6. The low water-cement ratio of the second cement slurry ensures that the anchor block has a high strength and a connection strength with the anchor rod assembly, thereby ensuring the connection stability between the anchor rod assembly and the bladder-type enlarged head.

[0026] Furthermore, there is a cement soil enlargement head between the bladder enlargement head and the common anchoring section. The cement soil enlargement head is formed by using the third cement slurry. When constructing the cement soil enlargement head, the grouting pressure is 25-35MPa. When the rotary jet drill rod forms the cement soil enlargement head, the rotary jet drill rod reciprocates and sprays at least twice. When forming the cement soil enlargement head, all cement slurries are the same as those of the common anchoring section and the free section, so as to reduce the preparation of cement slurry and improve the grouting efficiency. The use of the third cement slurry with a high water-cement ratio is conducive to the infiltration of cement slurry into the external soil body. While improving the strength of the external soil body, it also improves the connection strength between the external soil body and the cement soil in the anchor hole, and improves the stability of the anchor structure underground. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural diagram of an embodiment of the present application.

[0028] Figure 2 yes Figure 1 Enlarged view of part A.

[0029] Figure 3 yes Figure 2 Enlarged view of part B.

[0030] Figure 4 yes Figure 2 Magnified view of part C.

[0031] Figure 5This is the state diagram of the bladder before grouting.

[0032] Figure 6 This is a second fixing diagram of the bladder on the first anchor plate assembly.

[0033] Figure 7 This is the second installation diagram of the bladder.

[0034] Figure 8 yes Figure 7 Enlarged view of part D. DETAILED DESCRIPTION

[0035] Example 1

[0036] The following first describes the structure of the balloon-type enlarged head anchor rod. Figure 1-Figure 4 , along the length direction, the capsule-type enlarged head anchor rod structure includes an enlarged head section 201, a common anchoring section 202 and a free section 203 connected in sequence, wherein the enlarged head section and the common anchoring section are collectively referred to as the anchoring section, and the diameters of the common anchoring section and the free section are substantially the same. In this embodiment, the capsule-type enlarged head anchor rod structure is inclined, and it can be understood that in other embodiments, the capsule-type enlarged head anchor rod structure can also be vertical or horizontal. In specific construction, there is no special requirement for the extension direction of the capsule-type enlarged head anchor rod structure.

[0037] The bladder-type enlarged head anchor structure includes an anchor assembly 100 inserted into an anchor hole 200 and cement soil wrapped on the anchor assembly 100. In the attached drawings, the cement soil is not shown. The anchor hole 200 is formed by a rotary spraying process. The anchor assembly 100 includes an anchor cable group and a bladder bag 11. The anchor cable group includes a plurality of anchor cables 10. The pull-out end 101 of each anchor cable 10 is located in the enlarged head cavity 220 of the anchor hole 200. The tensioning end 102 of each anchor cable 10 extends out of the anchor hole 200. The bladder bag 11 is fixed to the pull-out end 101 and is located in the enlarged head cavity 220 of the anchor hole 200. There is an anchor block 210 formed by cement slurry in the bladder bag 11. The anchor block and the bladder bag together form a bladder-type enlarged head. There is an outer shell adjacent to the cement soil on the outside of the bladder bag. In this embodiment, there is also a cement soil enlarged head 230 on the side of the bladder bag facing the tensioning end. Figure 1 In the longitudinal direction, the area of ​​the bladder enlarged head is marked as S, and the area of ​​the cement soil enlarged head 230 is marked as M. The bladder enlarged head and the cement soil enlarged head together form an enlarged head section 201. In this embodiment, the outer diameter of the cement soil enlarged head is substantially the same as the outer diameter of the anchor block.

[0038] In this embodiment, two anchor disc assemblies are fixedly installed on the anchor cable group, and the two anchor disc assemblies are respectively a first anchor disc assembly 20 and a second anchor disc assembly 30, wherein the second anchor disc assembly 30 is located on the side of the first anchor disc assembly 20 away from the tensioning end, and the end of the bladder 11 facing the tensioning end is fixed to the first anchor disc assembly.

[0039] The structures of the two anchor plate assemblies are roughly the same, wherein the first anchor plate assembly 20 includes a first anchor plate 21 and a first extrusion plate 23. Corresponding to each anchor cable 10, a first anchor hole in the form of a through hole is provided on the first anchor plate 21. The end of the first anchor hole away from the tensioning end is formed into a first conical hole 25 with the small end facing the tensioning end. The first clip group 26 is arranged in the first conical hole 25. The first extrusion plate 23 is located on the side of the first anchor plate away from the tensioning end. The first locking bolt 24 connects the first extrusion plate to the first anchor plate, and the first extrusion plate tightly extrudes the clips in the first clip group 26 into the first conical hole to fix the anchor cable on the first anchor plate. In order to ensure the extrusion of the clips in the first clip group, a first extrusion tube 22 is sleeved on each anchor cable. The first extrusion tube is located between the clips of the first clip group and the first extrusion plate. The first extrusion plate is pressed against the clips of each first clip group through the first extrusion tube.

[0040] The second anchor plate assembly 30 includes a second anchor plate 31 and a second extrusion plate 33. Corresponding to each anchor cable 10, a second anchor hole in the form of a through hole is provided on the second anchor plate 31. The end of the second anchor hole away from the tensioning end is formed into a second conical hole 35 with the small end facing the tensioning end. The second clip group 36 is arranged in the second conical hole 35. The second extrusion plate 33 is located on the side of the second anchor plate away from the tensioning end. The second locking bolt 34 connects the second extrusion plate to the second anchor plate, and the second extrusion plate tightly squeezes the clips in the second clip group 36 into the second conical hole to fix the anchor cable on the second anchor plate. In order to ensure the extrusion of the clips in the second clip group, a second extrusion tube 32 is sleeved on each anchor cable. The second extrusion tube is located between the clips of the second clip group and the second extrusion plate. The second extrusion plate is pressed against the clips of each second clip group through the second extrusion tube.

[0041] Please continue to refer to 3. In this embodiment, the end of the bag 11 facing the tensioning end is an open end, and the end of the bag 11 away from the tensioning end is a closed end. The bag is sleeved on the end of the anchor assembly away from the tensioning end. A first clamping ring 13 is provided on the side of the first anchor plate 21 away from the second anchor plate assembly. The edge of the open end is tightly clamped between the first anchor plate and the first clamping ring 13. The first clamping bolt 14 passes through the first clamping ring 13 and is screwed on the first anchor plate to seal the end of the bag facing the tensioning end on the first anchor plate assembly. The second anchor plate assembly is accommodated in the bag.

[0042] When fixing the bag, it is generally not necessary to set a special seal. Since the bag is mainly made of organic materials such as HDPE, PVC or PPTA, it has a certain elasticity and has a strong sealing effect. If the open end is not easy to install, a special joint can be set at the open end to facilitate installation. Of course, a seal can also be installed when necessary.

[0043] It is understood that in another embodiment, a guide member can also be provided on the side of the second anchor assembly away from the first anchor assembly to reduce the resistance of the anchor assembly when inserted into the anchor hole. After the guide member is provided, the guide member is also wrapped in the bladder bag.

[0044] It is understood that in another embodiment, the bladder bag can also be fixed to the first anchor plate assembly by a hoop method, see Figure 5 When the bladder is fixed by a hoop, an upper ring 12 adapted to the outer peripheral surface of the first anchor plate needs to be provided at the open end of the bladder, and the upper hoop 18 tightly and sealingly binds the upper ring to the outer peripheral surface of the first anchor plate.

[0045] A grouting pipe hole 212 and an exhaust pipe hole 213 are provided on the first anchor plate 21, wherein the grouting pipe hole 212 is used to insert the grouting pipe 301, and the exhaust pipe hole 213 is used to insert the exhaust pipe 302. When one end of the grouting pipe and the exhaust pipe are respectively inserted into the grouting pipe hole and the exhaust pipe hole, the other ends of the grouting pipe and the exhaust pipe both extend outward from the anchor hole. The grouting pipe and the exhaust pipe are both connected to the inner cavity of the bag.

[0046] To improve the sealing performance, in this embodiment, sealing rings are provided between the grouting pipe and the grouting pipe hole, and between the exhaust pipe and the exhaust pipe hole. In the accompanying drawings, the sealing rings are not shown. In the specific construction, the installation of pipeline sealing rings in the prior art can be used to complete the installation, which will not be repeated here.

[0047] Cement slurry can be injected into the bag through the grouting pipe to form the anchor block 210. During the process of injecting the cement slurry into the bag, the gas in the bag can be discharged from the anchor hole 200 through the exhaust pipe.

[0048] A first center hole 211 is provided at the center of the first anchor plate 21, and a through-plate hole 231 is provided at the center of the first extrusion plate 23. A second center hole 311 is provided at the center of the second anchor plate 31, and the jet grouting drill rod 300 can pass through the first center hole 211 and press against the second center hole 311, so that the anchor rod assembly 100 is sent into the anchor rod hole 200. The first center hole 211, the through-plate hole 231, and the second center hole 311 are all through holes and are coaxially arranged to facilitate the penetration of the jet grouting drill rod.

[0049] In order to avoid the situation where the grouting pressure cannot be increased when grouting into the bladder due to the gap between the rotary jet drill rod and the first center hole 211, thereby affecting the grouting effect, in this embodiment, a rubber sealing ring 214 is embedded in the inner wall of the first center hole. When the rotary jet drill rod passes through the first center hole, the rubber sealing ring 214 seals the gap between the rotary jet drill rod and the inner wall of the first center hole, thereby improving the sealing of the bladder.

[0050] Example 2

[0051] This embodiment is basically the same as Embodiment 1, and the only difference is that the structure and installation method of the bag are slightly different.

[0052] See also Figure 7 and Figure 8 In this embodiment, the end of the bag 11 facing the tensioning end is the same as that in the first embodiment, but the end of the bag 11 facing away from the tensioning end is also open. For the convenience of description, the end of the bag 11 facing away from the tensioning end is called the open end. A second clamping ring 16 is provided on the side of the second anchor plate 31 facing the first anchor plate assembly. The edge of the open end is tightly clamped between the second anchor plate and the second clamping ring 16. The second clamping bolt 17 passes through the second clamping ring 16 and is screwed on the second anchor plate to seal the open end of the bag on the second anchor plate assembly. When installing the bag, the open end needs to be fixed on the second anchor plate first, and then the open end needs to be fixed on the first anchor plate.

[0053] Of course, in another embodiment, the second clamping bolt 17 may also be passed through the second anchoring plate and screwed onto the second clamping ring.

[0054] It can be understood that in another embodiment, the fixing of the opening end to the second anchor plate can also be done by a hoop. For details, please refer to the corresponding contents in Embodiment 1 and Figure 5 , no more details.

[0055] A guide cap 50 is welded on the side of the second anchor plate away from the first anchor plate assembly, and the guide cap and the second anchor plate together close the open end. That is, the guide cap and the second anchor plate assembly together close the end of the bag away from the tensioning end. In order to allow the cement slurry to smoothly enter the guide cap 50, six slurry through holes 312 are opened on the second anchor plate, and the six slurry through holes 312 are evenly spaced around the second center hole 311, and a slurry through hole 331 is opened in the center of the second extrusion plate 33 to speed up the cement slurry to enter the space between the second extrusion plate 33 and the end of the guide cap. It can be understood that the guide cap can also be installed on the second anchor plate in a detachable manner.

[0056] It can be understood that in another embodiment, the guide cap can be eliminated, and the second center hole 311 and the slurry through hole 312 on the second anchor plate can be eliminated, and the second anchor plate can be used to close the open end, that is, the second anchor plate assembly closes the end of the bag away from the tensioning end. In order to facilitate the positioning of the jet grouting drill rod on the second anchor plate, a blind hole can be provided on the side of the second anchor plate facing the first anchor plate assembly, and when the jet grouting drill rod delivers the anchor rod assembly 100 into the anchor rod hole 200, the head of the jet grouting drill rod is inserted into the blind hole.

[0057] Example 3

[0058] The construction method of the bladder-type enlarged head anchor structure in the above-mentioned embodiments 1 and 2 is described below, and the steps are as follows:

[0059] (1) The anchor hole is drilled by a jet grouting drill rod of a jet grouting drill, and an enlarged head cavity is formed at a set position. When drilling the anchor hole, a first cement slurry is sprayed outward through the jet grouting drill rod, and the first cement slurry forms cement soil with the soil.

[0060] When drilling the anchor hole, first use 12MPa grouting pressure to form the hole, and then use 30MPa grouting pressure to form the enlarged head cavity; the water-cement ratio of the first cement slurry is 1.2.

[0061] (2) After the drilling of the anchor hole is completed, the jet grouting drill rod is pulled out of the anchor hole, and then the head of the jet grouting drill rod is passed through the first center hole 211 and the through-plate hole 231, and then pressed against the edge of the second center hole 311, and the jet grouting drill rod is used to insert the anchor assembly carrying the grouting pipe and the exhaust pipe into the anchor hole, and the bag is located in the enlarged head cavity. Figure 6 At this time, under the pressure of the cement soil in the anchor hole, the bladder is attached to the components of the anchor assembly. Figure 6 In the embodiment, the bag is not attached to the components of the anchor assembly. One end of the grouting pipe and the exhaust pipe are both inserted into the bag, and the other ends are both extended outward from the anchor hole.

[0062] (3) The second cement slurry is injected into the bladder bag through the grouting pipe, and the air in the bladder bag is discharged to the outside through the exhaust pipe; after the second cement slurry solidifies, it forms an anchor block 210, and the anchor block and the bladder bag together form a bladder-type enlarged head; when the second cement slurry is injected into the bladder bag, the grouting pressure is 5 MPa, and the water-cement ratio of the second cement slurry is 0.5.

[0063] During the process of injecting the second cement slurry into the bladder bag, the rotary jet drill rod needs to be always inserted in the first center hole of the first anchor plate, and during the injection of the second cement slurry, the rotary jet drill rod is slowly pulled out, but the end of the rotary jet drill rod must be kept in the first center hole. After the injection of the second cement slurry is completed, the rotary jet drill rod is completely pulled out of the first center hole to carry out the construction of the cement soil enlargement head.

[0064] After the grouting into the bag is completed, the jet grouting drill rod is moved outward. When the jet grouting drill rod is separated from the bag, the third cement slurry is sprayed at a grouting pressure of 30 MPa to form a cement soil enlarged head. The cement soil enlarged head and the bladder-type enlarged head together form an enlarged head section 201. The water-cement ratio of the third cement slurry is 1.2. When the jet grouting drill rod forms the cement soil enlarged head, the jet grouting drill rod reciprocates and sprays at least twice. Grouting into the bag needs to be completed before the cement soil in the anchor hole completes initial setting.

[0065] It is understandable that in another embodiment, the cement soil enlargement head can be eliminated, and after the second cement slurry is injected into the bag, the grouting of the common anchoring section and the free section in step (3) can be directly performed.

[0066] (4) Inject the third cement slurry into the common anchor section and the free section. The grouting pressure in the common anchor section and the free section is 12 MPa.

[0067] (5) When the grout in the anchor hole reaches a set strength, the anchor cable is tensioned and locked. The grout in the anchor hole includes the second cement grout in the bag and cement soil formed by mixing the first cement grout and the third cement grout with the soil.

[0068] In this embodiment, the water-cement ratio of each cement slurry is the weight ratio of water to cement.

Claims

1. A balloon-type enlarged head anchor structure, characterized in that: It includes an anchor rod assembly inserted into an anchor rod hole and cement soil wrapped on the anchor rod assembly. The anchor rod hole is formed by a rotary spraying process. The anchor rod assembly includes an anchor cable group and a bladder. The anchor cable group includes a plurality of anchor cables. The pull-out end of each anchor cable is located in the enlarged head cavity of the anchor rod hole. The tensioning end of each anchor cable extends outward from the anchor rod hole. The bladder is fixed to the pull-out end and is located in the enlarged head cavity of the anchor rod hole. An anchor block formed by cement slurry is provided in the bladder.

2. The balloon-type enlarged head anchor structure according to claim 1, characterized in that: Two anchor plate assemblies are fixedly installed on the anchor cable group, and the two anchor plate assemblies are respectively a first anchor plate assembly and a second anchor plate assembly, wherein the second anchor plate assembly is located on the side of the first anchor plate assembly away from the tensioning end, and the end of the bag facing the tensioning end is sealingly fixed to the first anchor plate assembly; a grouting pipe hole and an exhaust pipe hole are opened on the first anchor plate assembly, wherein the grouting pipe hole is used for inserting the grouting pipe, and the exhaust pipe hole is used for inserting the exhaust pipe, when one end of the grouting pipe and the exhaust pipe are respectively inserted into the grouting pipe hole and the exhaust pipe hole, the other ends of the grouting pipe and the exhaust pipe both extend outward from the anchor rod hole; a center hole is arranged on the first anchor plate assembly, and the rotary jet drill rod can sealably pass through the center hole and then press against the second anchor plate assembly to send the anchor rod assembly into the anchor rod hole.

3. The balloon-type enlarged head anchor structure according to claim 2, characterized in that: One end of the bladder away from the tensioning end is sealingly fixed to the second anchor plate assembly, and the second anchor plate assembly closes the end of the bladder away from the tensioning end; or the end of the bladder away from the tensioning end is sealingly fixed to the second anchor plate assembly, a guide cap is fixedly installed on the side of the second anchor plate assembly away from the tensioning end, and a slurry hole connecting the guide cap and the bladder is provided on the second anchor plate assembly, and the guide cap and the second anchor plate assembly together close the end of the bladder away from the tensioning end.

4. The balloon-type enlarged head anchor structure according to claim 2, characterized in that: One end of the bladder away from the tensioning end is a closed end, and the second anchor plate assembly is located in the bladder.

5. The balloon-type enlarged head anchor structure according to claim 2, characterized in that: Each anchor plate assembly includes an anchor plate and an extrusion plate. Corresponding to each anchor cable, an anchor hole in the shape of a through hole is provided on the anchor plate. The end of the anchor hole away from the tensioning end is formed into a conical hole with the small end facing the tensioning end. A clip group is arranged in the conical hole. The extrusion plate is located on the side of the anchor plate away from the tensioning end. The locking bolt connects the extrusion plate to the anchor plate, and the extrusion plate tightly squeezes the clips in the clip group into the conical hole to fix the anchor cable on the anchor plate.

6. The balloon-type enlarged head anchor structure according to claim 2, characterized in that: A cement soil enlarged head is arranged on one side of the bladder bag facing the tensioning end, and the diameter of the cement soil enlarged head is greater than the diameter of the free section.

7. The construction method of the balloon-type enlarged head anchor structure according to any one of claims 1 to 6, characterized in that: The steps include: (1) drilling an anchor hole using a jet grouting drill rod and forming an enlarged head cavity at a set position; when drilling the anchor hole, spraying a first cement slurry outward through the jet grouting drill rod, and the first cement slurry forms cement soil with the soil; (2) inserting the anchor assembly carrying the grouting pipe and the exhaust pipe into the anchor hole by using the jet jet drill rod, and positioning the bag in the enlarged head cavity; (3) injecting a second cement slurry into the bladder bag through the grouting pipe to form a bladder-type enlarged head, and the air in the bladder bag is discharged to the outside through the exhaust pipe; (4) injecting the third cement slurry into the common anchoring section and the free section; (5) When the slurry in the anchor hole solidifies and reaches the set strength, the anchor cable is tensioned and locked.

8. The construction method according to claim 7, characterized in that: In step (1), when drilling the anchor hole, firstly, a grouting pressure of 10-15 MPa is used to form the hole, and then a grouting pressure of 25-35 MPa is used to form the enlarged head cavity; the water-cement ratio of the first cement slurry is 1.0-1.5; In step (4), the grouting pressure in the common anchoring section and the free section is 10-15 MPa, and the water-cement ratio of the third cement slurry is 1.0-1.

5.

9. The construction method according to claim 7, characterized in that: In step (3), when the second cement slurry is injected into the bag, the grouting pressure is 4-8 MPa, and the water-cement ratio of the second cement slurry is 0.4-0.

6.

10. The construction method according to claim 7, characterized in that: There is also a cement soil enlargement head between the bladder enlargement head and the ordinary anchoring section. The cement soil enlargement head is formed by using the third cement slurry. When constructing the cement soil enlargement head, the grouting pressure is 25-35MPa; when the rotary jet drill rod forms the cement soil enlargement head, the rotary jet drill rod reciprocates and sprays at least twice.

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