JP2006274728A - Ground anchor construction method and structure of ground anchor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ground anchor construction method for suppressing gushing-out of underground water completely even in the ground of high artesian water to improve workability and preventing intrusion of mud and water due to direct exposure of an anchor tendon to the underground water even temporarily. <P>SOLUTION: In this ground anchor construction method and the structure of the ground anchor, the whole tendon 6 inserted and fixed in an anchor hole is wrapped by a cylindrical restraining body 8 by leaving an end part to be tightly stretched and fixed to prevent underground water from intruding into it, a rear end part side of the restraining body is constituted by a straight pipe 13 with an aramid packer 10 and is connected with a water cut-off plate 5a provided in an anchor head part 7, grout is poured into the anchor hole 4 to fill a clearance between an outer peripheral face of the restraining body and the anchor hole, grout is poured into an inner side of the restraining body to fill a clearance between the tendon and an inner face of the restraining body, and the tendon is tightly stretched and fixed to the anchor head part 7 provided in a building after each poured grout is solidified. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a ground anchor method that functions effectively on the ground where pressurized groundwater exists, and a ground anchor structure obtained by the method.

  Conventionally, as this type of groundwater construction method of a pressurized groundwater type, for example, a guide tube is driven into a through hole cut in a continuous wall, a water stop box is attached to the head of the guide tube, and the guide tube is attached to the guide tube. While inserting the casing with the Kronen bit with a check valve at the tip, rotate and drill with a drilling machine to connect and insert multiple single pipe casings and insert the inner rod into those casings to the bottom After injecting the injection material and pushing out the kronen bit, insert an assembly with multiple strands aligned with spacers and a stretchable water stop packer in the middle, and pressurize the head of the casing The head is attached, the water-stopping packer is expanded while pressurizing and injecting the injection material through the pressure head to seal between the assembly and the casing, and the casing is pulled out from the pulled out casing. The next connection is disconnected, and when the last casing exceeds the packer, the packer is inflated to seal between the guide tube and the assembly, and the water stop box is removed and water is stopped from the injection hose attached to the spacer. An anchor construction method under pressured water, constructed by injecting material, curing the injected material, and building an anchor for fixing the stranded wire to fix the connecting wall to the ground The anchor structure made is known (see Patent Document 1).

  In this known anchor construction method, when the casing is pulled out, the water-stop packer is expanded to seal between the assembly and the casing, the casing is pulled out, the connection is separated from the pulled casing, and the last casing is When the water-stopping packer is exceeded, the water-stopping packer is inflated to seal between the assembly and the guide tube, preventing backflow of water and earth and sand, and stopping water with the injected water-stopping material. It is possible to build a strong anchor on the ground with much.

  In addition, a woven cloth bag is covered in a range corresponding to the fixing portion of the uncurtain don, a grout injection tube is inserted into the bag, the opening of the bag is sealed, and the grout injection tube covered with this bag After inserting the uncurtain don containing the anchor hole into the anchor hole, the grouting material is pressurized and injected from the grouting pipe, and the bag body is pressurized and filled until the outer peripheral surface of the bag is in pressure contact with the hole wall of the anchor hole. An anchor construction method and an anchor structure constructed thereby are known (see Patent Document 2).

  In this known anchor construction method, since the outer peripheral surface of the bag body is pressurized and filled until it pressurizes and adheres to the hole wall of the anchor hole, the groundwater moves so rapidly that the ground flows out of highly pressurized water. Even if it is, the filled grout material is not washed or diluted before solidifying, the anchor cannot be formed, the adhesion between the anchor body and the ground is adversely affected, and the predetermined anchor strength is obtained. All the issues such as not being solved are solved.

  In any case, the known anchor construction method or construction method is said to be a technique for countermeasures against pressurized water, but due to the structure of the water stop packer, the water stop for the uncurtain dong is insufficient, The uncurtain dong disposed as a tension material inside the anchor structure is a structure in which the periphery thereof is directly hardened with a grout material.

JP-A-6-306860 JP 2002-129555 A

  By the way, in these known anchor construction or construction methods, in short, the former construction method is an assembly in which a plurality of strands (tendons) that are tendon materials are aligned with spacers and a stretchable waterproof packer is provided in the middle. It is formed, and the water-stopping packer is inflated while pressure-injecting the injection material through the pressure head to seal between the assembly and the casing, but the water-stopping packer is inflated. However, it is impossible to stop water between the strands, and if you insert an assembly into the casing and inject an injection material (grouting), groundwater will be ejected from between the strands. It cannot respond to.

  In the latter construction method, a bag made of woven cloth is covered in a range corresponding to the fixing portion of the an curtain curtain, the an curtain curtain is inserted into the anchor hole, and a grout material is injected under pressure into the bag body. The groundwater overflows from the opening of the anchor hole while the grout material is being filled in the bag and the anchor hole until the outer peripheral surface of the container is in pressure contact with the hole wall of the anchor hole. It keeps doing. And about water stop, the mouth packer is finally set to the mouth of an anchor hole, and grout materials, such as cement milk, are inject | poured and filled in this mouth packer until it confirms that flowing water stops.

  In any of the known examples, water stoppage is insufficient during construction such as drilling or grout injection, and the groundwater that is blown out interferes with the work. In particular, it will be exposed directly to the eruption, and in particular, mud and water may invade between the strands of the fixing part, and solidification by the grout may be insufficient, or rust may be generated over time. As this grows, problems arise in the fixing and strength with the solidified grout material.

  Therefore, in the anchor structure constructed by the conventional anchor construction or construction method, it is possible to improve the workability by completely suppressing the ejection of groundwater even in the ground of high pressure water, and the uncurtain dong is temporarily In any case, it has a problem that must be solved by preventing direct intrusion of mud and water by direct exposure to groundwater.

  As a concrete means for solving the problems of the conventional example described above, the first invention is to fix an anchor hole in the ground in order to fix the slope of the ground or the underground structure where the pressurized groundwater exists, After the tendon is inserted into the hole and grout is injected and solidified, it is a ground anchor method in which the tendon is tension-fixed to the anchor head provided in the structure, and the tendon inserted into the anchor hole is The whole body is wrapped with a cylindrical restraining body so that the groundwater does not enter, leaving the end to be tension-fixed, and the rear end side of the restraining body is composed of a straight tube with an aramid packer and provided at the anchor head Connected to the water stop plate, injecting grout into the anchor hole to fill the gap between the outer peripheral surface of the restraint body and the anchor hole, and further injecting grout into the inside of the restraint body, tendon and restraint body Filling the gap between the surfaces, and most important feature ground anchor method consisting in the grout that these injection nervous secured to the anchor head which is provided to construct the tendon after solidification.

  The second invention is a ground anchor structure which is constructed on the ground where the pressurized groundwater exists, and a tendon is inserted into the anchor hole which has been cut, injected into a grout and solidified, and the tendon is tension-fixed to the anchor head. The entire tendon that is solidified with grout is wrapped with a cylindrical restraint so that groundwater does not spout, and the rear end of the restraint consists of a straight tube with an aramid packer. And the ground anchor structure which consists of connecting with the water stop board provided in the anchor head is the main feature.

  Further, in the first ground anchor method and the second ground anchor structure according to the present invention, the cylindrical restraining body uses a different diameter pipe or a spiral pipe at least for the fixing portion on the tip side; The cylindrical restraint is a steel pipe or a stainless steel anticorrosive pipe that has been rust-proofed by galvanization, and is formed by connecting a plurality thereof; and the cylindrical restraint is provided with an uneven portion. Is included as an additional requirement.

In the ground anchor construction method of the present invention having the above-described configuration, the tendon inserted into the anchor hole wraps the whole with a cylindrical restraining body so that the groundwater does not enter, leaving an end portion to be tension-fixed. Therefore, even if it is constructed on the ground where high-pressure groundwater exists, groundwater and mud do not enter between tendons, and the rear end of the restraint is composed of straight pipes with aramid packers. Since the water is stopped between the smooth surface and the smooth surface of the anchor hole, the workability can be improved by completely suppressing the ejection of groundwater from between the tendons or from the anchor hole.
Also, in the ground anchor structure, since the entire tendon is encased in a cylindrical restraint, groundwater and mud do not enter between tendons even in the ground where highly pressurized groundwater exists, and the rear end of the restraint Since the part side is composed of straight pipes with aramid packers, the ejection of groundwater is suppressed, so the tendon is not exposed to the groundwater at all, so there is no rust, and the strength of the constructed anchor itself is Remarkably improved.

In the present invention, in order to fix the slope or underground structure of the ground where the pressurized groundwater exists, anchor holes are cut in the ground, and tendons are inserted into the anchor holes and grout is injected to solidify. It is a ground anchor method that tensions and fixes the tendon to the anchor head provided in the structure, but especially for the tendon that is inserted into the anchor hole, the groundwater does not enter leaving the end to be tensioned and fixed. The whole body is wrapped with a cylindrical restraint body, and the restraint body is configured by connecting a plurality of pipe bodies, and the rear end portion side is composed of a straight tube with an aramid packer and a front end. Different diameter pipes or spiral pipes are used on the side, and the straight pipe with aramid packer on the rear end side is connected to a water stop plate provided on the anchor head to perform almost complete water stop. The grout is injected into the anchor hole to fill the gap between the outer peripheral surface of the restraint body and the anchor hole, and further, the grout is injected inside the restraint body to fill the gap between the tendon and the restraint body inner surface. This is realized by tensioning the tendon to the anchor head provided in the structure after the grout has solidified.
By configuring in this way, even in the ground where high pressure groundwater exists, various problems due to groundwater ejection are solved at once.

  FIG. 1 shows a specific embodiment of a ground anchor structure according to the present invention. The ground anchor method is conventionally used except that a special restraint body of an uncurtain dong (hereinafter simply referred to as tendon) is used. The process being performed can be used as it is. That is, the anchor fixing hole 3 is provided in, for example, a concrete structure (hereinafter referred to as a structure) 2 on the slope or the underground structure of the ground 1 where there is a high pressure groundwater with a lot of groundwater. In drilling the anchor hole 4 having a required depth, the water stop box 5 is attached to the anchor fixing hole 3.

  In the state of passing through the water stop box 5, first, the core boring hole 4 a is drilled in the structure 2, and then an anchor having a predetermined depth is fixed to the ground 1 by a known drilling machine having a drilling bit attached to the tip. The hole 4 is drilled continuously to the core boring hole 4a. A guide tube may be attached to the core boring hole 4a.

  After drilling an anchor hole 4 of a predetermined depth in the ground 1, the drill bit at the tip is cut off and left at the bottom of the anchor hole 4 to pull out the tube rod of the drilling machine. Is to be inserted.

  The tendon 6 in this case uses a plurality of PC steel strands, and the PC steel strands are subjected to a rust-proof coating treatment by forming a thermosetting or thermoplastic synthetic resin film, for example, Seven known twisted ones can be used as they are, and those not subjected to rust prevention treatment can also be used.

  In the case of the present invention, the tendon 6 is disposed in a state where the entire tendon 6 is wrapped in a cylindrical restraint 8 so that the groundwater does not come into direct contact. In other words, a tubular restraining body 8 is inserted into the anchor hole 4, and the rear end portion of the restraining body 8 is welded to the water stopping plate 5 a of the water stopping box 5 so that the groundwater does not enter inside. After the attachment, the tendon 6 is inserted into the restraint 8 so that the whole is wrapped.

  As shown in FIG. 2, the restraint 8 in this case is a tube having rigidity made mainly of metal, and is a steel tube that has been rust-prevented by galvanizing or a stainless steel tube having a required length having corrosion resistance. It is used, and a plurality (books) are connected to correspond to the length of the tendon 6 so as to correspond to the length, and the type of the tube and the parts for connection will be described.

  For example, (A) in FIG. 2 shows a straight tube 9 with a packer that is attached to the rear end side, which is the anchor head side, and connection threads 9a and 9b are formed at both ends, An aramid packer 10 is integrally attached so as to cover the peripheral surface of the intermediate portion of the straight tube 9 with a packer, and a grout injection tube 11 that penetrates the aramid packer 10 and extends along the tube wall is provided. The aramid packer 10 is provided with an air supply pipe 12.

  FIG. 2 (B) shows a straight tube 13 disposed mainly in a free length portion of the tendon 6, and screw threads 13 a and 13 b are also formed at both ends of the straight tube 13.

  2 (C) shows a different diameter pipe or spiral pipe 14 mainly disposed in the fixing portion of the tendon 6 and uses a different diameter pipe having an entire outer peripheral surface formed in a waveform. Alternatively, a spiral tube having spiral irregularities is used, and screw threads 14a and 14b are formed at both ends thereof. In the case of this different diameter pipe or spiral pipe 14, in essence, an uneven portion may be formed in the pipe itself, or a wire having a required thickness may be wound around at least the outer peripheral surface of the straight pipe in a spiral shape and welded.

  Further, FIG. 2 (D) shows a coupling 15 used for connecting the above-mentioned tubes 9, 13, and 14. The coupling 15 is formed with screw portions 15a and 15b at both ends. ing. FIG. 2 (E) shows a cap 16 attached to the distal end portion of the different diameter tube or spiral tube 14. The cap 16 has a threaded portion 16a on one end side, and the other end side. Has a closed configuration. Further, FIG. 2 (F) shows a flexible joint 17, and threaded portions 17a and 17b are formed at both ends of the flexible joint 17, and can be used at appropriate positions if necessary.

  In any of the above-described tubes 9, 13 and 14, for example, the length of the short tube is 50 cm, and the length of the long tube is about 2 m. The depth of the anchor hole 4 and the length of the tendon 6 are prepared. It can be appropriately selected and used correspondingly.

  For example, in the ground anchor structure shown as an example in FIG. 1, for example, the length L1 of the anchor head portion 7 is 70 cm, the thickness L2 of the pressure-resistant wall is 1.5 m, and the length L3 is a free length. Is 5.0 m and the fixing portion length L4 is 10.0 m, a straight tube 9 with a packer having a length of 1.40 m is used, and a flexible joint 17 having a length of about 10 cm is used for this. Then, the straight tube 13 disposed in the free length portion is connected. For example, a straight pipe 13 having a length of 1 m is selected, and a predetermined length is obtained by sequentially adding five straight pipes 13 via a coupling 15.

  In addition, by using the flexible joint 17 in a part of the restraint body 8, since it can be freely deformed at the joint portion, in the ground where the high pressure groundwater exists, the buoyancy generated by the groundwater pressure is absorbed by the deformation, For example, even when vertical or horizontal displacement or excessive tension occurs due to an earthquake or the like, the anchor head 7 is absorbed by deformation of the joint portion so as not to be broken, and further, the core boring hole 4a. Even if there is a slight angular shift in the anchor hole 4 from the tip, it can be deformed to follow it.

  Further, a different diameter tube or a spiral tube 14 is connected to the straight tube 13 via a coupling 15. In this case, for example, if a 2.0 m different diameter pipe or a spiral pipe 14 is selected, the length is set by connecting five pipes. Then, the cap 16 is attached to the free end portion of the different diameter pipe or the spiral tube 14 located at the distal end portion, and the confining body 8 is completed by sealing the groundwater from entering the tube from the distal end portion.

  The depth of the anchor hole 4 and the length of the tendon 6 are determined at the design stage depending on the state of the ground 1 where there is a large amount of groundwater under pressure, and the length of the tendon 6 is determined. The number of parts used as 8 and the lengths and numbers of the pipes 9, 13, and 14 are inevitably determined, and the tendon 6 is formed in a state in which the spacers are sandwiched and aligned and bundled in advance at the factory. The restraint body 8 may be brought into the construction site without connecting the pipes and appropriately connected at the stage of being inserted into the drilled anchor hole 4.

  Then, the restraint 8 is inserted into the anchor hole 4 and attached to the water blocking plate 5a. After the tendon 6 is inserted into the restraint 8, the positioning is performed. First, air is supplied from the air supply pipe 12 to aramid packer. 10 is inflated and pressed against the wall surface of the core boring hole 4a to prevent groundwater from being ejected. In particular, the aramid packer 10 exhibits a so-called complete waterproofing function by tightly blocking water between the smooth outer peripheral surface of the tube 9 and the smooth wall surface of the core boring hole 4a. By doing in this way, groundwater does not penetrate | invade also into the inside of the restraint body 8, and it can interrupt | block completely that groundwater ejects from the anchor hole 4. FIG.

After the groundwater is thus blocked, the grout is injected from the grout injection pipe 11 into the anchor hole 4 at a high pressure, and the grout is also injected into the restraint 8. In this case,
The grout may be injected into the anchor hole 4 and the restraint 8 at the same time or separately with a time difference. For example, if the grout is injected into the restraint 8 first, since the groundwater does not enter the restraint 8, the air is only released from the rear end side at the time of the grout injection. Alternatively, the grout can be injected in a short time, and then the grout may be injected into the anchor hole 4.

  Since the tendon 6 in the state in which the periphery is encased in the anchor hole 4 by the restraint 8 is disposed, the anchor hole 4 is filled with groundwater, and groundwater escape is restricted when the grout is injected. Since the injection is performed at a high pressure, the water pressure increases and the injection time takes longer. Therefore, if the grout is first injected into the restraint 8, the restraint 8 is not affected even if the water pressure in the anchor hole 4 increases.

  FIG. 3 shows an enlarged cross section of the ground anchor structure in a state after injecting grout. 3A is a cross-sectional view of the back end of the straight tube 9 with a packer, FIG. 3B is a cross-sectional view of the free length portion, and FIG. 3C is a cross-sectional view of the fixing portion. It is. As is clear from these cross sections, the grout 18 injected inside the restraint 8 is uniformly injected between the PC steel strands, and the grout 19 injected into the anchor hole 4 And the outer peripheral surface of the restraint body 8 are uniformly filled.

  Then, after the injected grout is sufficiently solidified, the PC steel strands of the tendons 6 may be tension-fixed by the tension fixing means similar to the known technique in the anchor head 7. At this time, in the fixing portion of the tendon 6, the different-diameter pipe or spiral pipe 14 constituting the restraint 8 has an uneven surface, so that the engagement strength between the inner grout 18 and the outer grout 19 is high. Since it is highly integrated, no misalignment or the like occurs, and the PC steel strand is in a state where the synthetic resin coating of the outer tube is removed and the strand itself is solidified with the grout 18. There is no risk of misalignment or the like in the portion.

  Unlike the conventional method, the ground anchor method and its structure according to the present invention surround the tendon 6 in a watertight state with the restraint 8, so that the ground anchor is attached to the ground where there is a lot of groundwater under pressure. During construction, when tendon is inserted into the drilled anchor hole, groundwater or mud does not enter the gap between tendons, and when grout is injected, groundwater may spout from the gap between the tendons and the water stop packer attachment. Since it is completely eliminated, the workability is good, and it can be used significantly when ground anchors are constructed on all grounds with a lot of groundwater.

1 is a side view schematically showing a specific ground anchor structure according to a first embodiment of the present invention. It is a component diagram which comprises the restraint body of tendon in the same invention, (A) is a side view of a straight pipe with an aramid packer, (B) is a side view of a straight pipe disposed in a free length part, (C) is a fixing (D) is a side view showing a coupling for connection, (E) is a side view showing a tip cap, and (F) is a side view of a flexible joint. is there. It is sectional drawing of the principal part in the ground anchor structure of FIG. 1, (A) is an expanded sectional view which follows the AA line, (B) is an expanded sectional view which follows the BB line, (C) is CC It is an expanded sectional view which follows a line.

Explanation of symbols

1 Ground 2 Concrete structure (structure)
3 Anchor fixing hole 4 Anchor hole 4a Core boring drilling hole 5 Water stop box 5a Water stop plate 6 Uncurtain dong (Tendon)
7 anchor head 8 restraint body 9 straight tube with packer 9a, 9b, 13a, 13b, 14a, 14b, 15a, 15b, 16a, 17a,
17b Thread 10 Aramid packer 11 Grout injection pipe 12 Air supply pipe 13 Straight pipe 14 Different diameter pipe or spiral pipe 15 Coupling 16 Cap 17 Flexible joint 18 Grout injected into restraint body 19 Grout injected into anchor hole

Claims (8)

In order to fix the slope of the ground where the groundwater under pressure exists or the underground structure, anchor holes are cut in the ground, tendons are inserted into the anchor holes, and grout is injected and solidified. It is a ground anchor method that tensions and fixes tendon to the anchor head provided in
The tendon inserted into the anchor hole is wrapped in a cylindrical restraint so that groundwater does not enter, leaving an end to be tension-fixed,
The rear end side of the restraint is composed of a straight tube with an aramid packer and connected to a water stop plate provided on the anchor head,
Injecting grout into the anchor hole to fill the gap between the outer peripheral surface of the restraint and the anchor hole,
Furthermore, grout is injected into the inside of the restraint to fill the gap between the tendon and the inside of the restraint,
A ground anchor method characterized in that after each of these injected grouts solidifies, tendon is tension-fixed to the anchor head provided in the structure. The ground anchor method according to claim 1, wherein the cylindrical restraining body uses a different diameter pipe or a spiral pipe at least at a fixing portion on a tip side. 3. The ground according to claim 1, wherein the cylindrical restraining body is a steel pipe or a stainless steel pipe having corrosion resistance treated by galvanization, and is formed by connecting a plurality thereof. Anchor construction method. The ground anchor method according to any one of claims 1 to 3, wherein the tubular constraining body is provided with an uneven portion. The ground anchor structure is constructed on the ground where the groundwater under pressure exists, and the tendon is inserted into the anchor hole that has been cut, injected into the grout and solidified, and the tendon is tension-fixed to the anchor head,
The entire tendon that is solidified by the grout is wrapped with a cylindrical restraint so that groundwater does not spout, and the rear end of the restraint consists of a straight tube with an aramid packer and the anchor head A ground anchor structure that is connected to a water stop plate provided in The ground anchor structure according to claim 5, wherein the cylindrical restraining body uses a different diameter pipe or a spiral pipe at least at a fixing portion on a distal end side. The ground according to any one of claims 5 to 6, wherein the cylindrical restraining body is a steel pipe or a stainless steel pipe having corrosion resistance treated by galvanization, and is formed by connecting a plurality thereof. Anchor structure. The ground anchor structure according to any one of claims 5 to 7, wherein the cylindrical constraining body is provided with an uneven portion.

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