JP2008088638A - Ground anchor and ground anchor method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ground anchor which prevents a decrease in initial tensile force introduced into an anchor body, even if the scouring of the soft ground of a surface layer and the adhesion resistance of the peripheral portion of the anchor body are reduced, and a ground anchor method. <P>SOLUTION: In this ground anchor 1, a plurality of compressed bodies 8 in each of which a protrusion 9 is formed on its outer periphery and a steel pipe 10 is provided are longitudinally connected to one another so that a prestressed concrete pile 6 can be formed. The prestressed concrete pile 6 is inserted into the grout 5 of an anchor hole 4 in the ground; and a tension member 7 which is arranged in the steel pipe 17 and the tip of which is protruded from the tip of the prestressed concrete pile 6 is guided out of an opening 19 of the anchor hole, subjected to a predetermined tensioning force, and anchored to an anchorage device 22 of the anchor plate 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a ground anchor and a ground anchor method.

Conventionally, as a ground anchor that stabilizes the ground of a slope, the invention of Japanese Patent Application Laid-Open No. 2004-353343 is known. Such a ground anchor has been applied in order to prevent the soft slope layer from collapsing due to a slip along the assumed slip surface. This ground anchor design is based on the stable design of the slip surface assuming the amount of soil in the soft slope layer as a load, the drilling diameter according to the amount of PC steel determined by the required tension, the anchoring length of the solid ground layer, The excavation head has been decided. Further, the anchor body after drilling was formed by inserting a PC steel material having a fixing plate and a load bearing body at the tip to a fixing layer of a solid ground, and filling mortar over the entire length of the hole. The PC steel head is attached to the anchor plate to prestress the soft ground layer, and the compressive force caused by this prestress is applied to the slip surface. The upward shear resistance force caused by this compressive force causes the soft ground layer to collapse. Is preventing.
JP 2004-353343 A

  However, since the above-mentioned ground anchor is prestressed on the surface layer for a long period of time, if the soft ground of the surface layer is scoured or if the adhesion resistance around the anchor body decreases, the anchor body In some cases, the initial tensile force introduced was reduced and the performance of the ground anchor was not satisfied.

  The present invention has been made in view of these problems, and its purpose is to provide an initial tensile force introduced into the anchor body even if the surface layer soft ground scouring or the adhesion resistance of the anchor body periphery decreases. It is to provide a ground anchor and a ground anchor method that does not deteriorate.

A ground anchor for solving the above problems is a prestressed concrete pile formed by connecting a plurality of compression trunks with protrusions formed on the outer peripheral portion and having steel pipes therein in the length direction. A concrete pile is inserted into the grout at the anchor hole in the ground, wired in the steel pipe, and a tensile material whose tip protrudes from the tip of the prestressed concrete pile is led out from the opening of the anchor hole and has a predetermined It is characterized in that a tension force is applied and the anchor plate is fixed to a fixing tool. In addition, a reinforcing bar or a steel pipe protrudes from the tip of the compression trunk installed at the lowermost end, and a tensile material is wired in the reinforcing bar or the steel pipe.
In addition, the ground anchor method is a compression trunk in which protrusions are formed on the outer periphery and a steel pipe is piped inside, a tensile material is wired in the steel pipe of the compression trunk, and the tensile material is wired. A plurality of other compression trunks are joined to the trunk to form a prestressed concrete pile, the prestressed concrete pile is inserted into an anchor hole in the ground, the grout is filled into the anchor hole, and the grout is cured. After that, the tensile material led out from the opening of the anchor hole is fixed to the anchor plate fixing device by applying a predetermined tension. In addition, a reinforcing bar or a steel pipe protrudes from the tip of the compression trunk installed at the lowermost end, and a tensile material is wired in the reinforcing bar or the steel pipe.

  Even if a slope slip of the surface layer occurs, the initial tensile force introduced into the anchor body does not decline. In addition, it can resist bending stress and shear force even when the load of soft ground layer is applied. In addition, even when slipping due to an earthquake occurs, the anchor body has a tensile performance, so that the soft ground layer can be easily repaired and the restoration period can be shortened. It can also be applied as a highly safe pile that can resist horizontal shear and bending stresses. In addition, when a wide road is created by cutting a narrow road condition in a mountainous area or a natural mountain, it can be easily constructed without bringing in heavy heavy machinery. Moreover, when applying as piles, such as an existing abutment or a retaining wall, it can construct with a low working height, without using a large excavator. Further, a reinforcing bar or a steel pipe protruding from the tip of the PC pile can be used as a leg when the PC pile is inserted into the anchor hole.

  Hereinafter, embodiments of the ground anchor and the ground anchor method of the present invention will be described. First, the ground anchor will be described, and then the ground anchor method will be described. In each embodiment, the same components will be described with the same reference numerals, and only different components will be described with different reference numerals.

  FIG. 1 shows a ground anchor 1 according to a first embodiment. This ground anchor 1 is prestressed concrete pile (hereinafter referred to as PC pile) in a grout 5 of an anchor hole 4 excavated from a soft ground layer 2 to a supporting ground layer 3. ) 6 is inserted, and a predetermined pre-stress is applied to the PC pile 6 with a tensile material 7.

  The PC pile 6 is formed by joining a plurality of compression trunk bodies 8 and 16 in the length direction. The compression trunk 8 is formed of any one of high-strength concrete, high-strength mortar, and ceramics, and circular protrusions 9 that enhance adhesion performance are formed on the outer peripheral portion at appropriate intervals in the length direction, and a core is formed inside. A steel pipe 10 serving as a material is piped to be hollow.

  Around the steel pipe 10, a reinforcing bar 13 composed of longitudinal bars 11 and spiral bars 12 is arranged, and a compression trunk is formed by a tension member 14 such as a PC steel wire or a PC steel bar wired in the length direction. 8 and 16 are prestressed.

  These compression trunks 8 are welded and joined at the steel plates 15 for joining at both ends or one end, and are joined on the ground before being inserted into the anchor holes 4 or joined while being inserted into the anchor holes 4. The number of pieces to be joined is determined according to the length of the PC pile 6.

  Further, the reinforcing bar 13 is protruded from the distal end portion of the compression trunk body 16 arranged at the foremost end, and this serves as a leg when the PC pile 6 is inserted into the anchor hole 4 to support the PC pile 6 and It is independent.

  Since the internal steel pipes 10 are also joined to each other by joining the compression trunk bodies 8, a single steel pipe 17 is formed in the PC pile 6, and the tensile material 7 is wired to the steel pipe 17. This tensile member 7 is a PC steel wire or a PC steel strand, and the lower part is a bare wire and is wired in the reinforcing bar 13 and attached to the grout 5, and is inserted into the sheath 18 in the steel pipe 17. Unbonded steel wire.

  Then, the tension member 7 is tensioned with a predetermined tension force to give a prestress to the PC pile 6, and an upper portion thereof is led out from the steel pipe 17 to the fixing tool 22 of the anchor plate 20 in the opening portion 19 of the anchor hole 4. It has been established.

  Since the lower part of the tension member 7 is wired as a bare wire in the reinforcing bar rod 13 protruding from the compression trunk body 8, it is attached to the grout 5 integrally with the reinforcing bar rod 13, and its adhesion strength is increased. Since it is protected by the reinforcing bar 13, it can be accurately wired in the grout 5 as a bare wire. Therefore, the grout 5 of the anchor hole 4 and the PC pile 6 are integrated to form a pile body 23.

  7 and 8 show a ground anchor 24 according to the second embodiment. This ground anchor 24 is obtained by removing a reinforcing bar from the distal end portion of the compression trunk body 16 located at the lowermost end. It is the same structure as the Guarland anchor 1 of 1 embodiment. Since there is no reinforcing bar, the tensile material 7 is a PC pile 26 fixed to the distal end portion of the compression trunk body 16 by a crimping grip 25, and the tensile material 7 is a bare wire not covered with a sheath.

  FIGS. 9 and 10 show a ground anchor 27 according to the third embodiment. This ground anchor 27 has a steel pipe 28 projecting from the distal end portion of the compression trunk body 16 located at the lowermost end. It is the same structure as the Guarland anchor 1 of 1 embodiment. The steel pipe 28 is an extension of the steel pipe 10 embedded in the compression trunk body 16, and protects the tensile material 7 in the same manner as the above-described reinforcing bar 13, and also when the PC pile 29 is inserted into the anchor hole 4. It becomes a leg and supports and self-supports the PC pile 29. On the circumferential surface of the steel pipe 28, a filling hole 30 for filling the grout 5 in the steel pipe 28 is opened.

  FIG. 11 shows an application of the ground anchor 1 according to the first embodiment to the embankment structure 31, which is used as a pile foundation that supports the foundation block 32 and an anchor that supports the retaining wall 33.

  In FIG. 12, the ground anchor 1 according to the first embodiment is applied to the slope, and is used as an anchor for protecting the slope 34.

  As described above, the ground anchor 1 uses the compression trunk body 8, and the initial tension force is applied thereto, so that the PC piles 6, 26, and 29 can be applied to the ground pile without applying the compressive stress of the surface layer. Prestress is applied to resist pulling force.

  Therefore, even if the surface layer is scoured, it is possible to easily repair the part that has been reused and scoured without re-working the anchor. It can also be applied to the pile method of retaining wall that receives axial force, horizontal shear force and bending moment.

  In addition, since the PC piles 6, 26, and 29 are formed by adding the compression trunk body 8, even when the work height and work space are limited, the work can be easily performed without using a large excavator. It can also be applied to the construction of seismic reinforcement piles.

  Next, the ground anchor method using the PC pile 6 of the first embodiment will be described.

  First, as shown in FIG. 13, a plurality of compression trunks 8 are formed in a factory, and these are carried to the site. Among these compression trunks 8, the compression trunk 16 located at the lowermost end has a reinforcing bar 13 protruding from the tip. Then, a tensile material 7 such as a PC steel wire is inserted into the steel pipe 10 of the compression trunk 16 from which the reinforcing bar 13 protrudes from the tip part, and the lower part is wired to the reinforcing bar 13 and the rear part is connected to the reinforcing bar 13. Derived from the upper end.

  Next, the anchor hole 4 is excavated from the soft ground layer 2 to the support ground layer 3, and the anchor plate 20 is installed on the upper surface of the soft ground layer 2 so as to match the insertion port 21 with the opening 19 of the anchor hole.

  Next, the compression trunk body 16 wired with the tensile material 7 is inserted into the anchor hole 4, and another compression trunk body 8 is added to the anchor hole 4, and the joining steel plates 15 are welded to each other. Further, when another compression trunk body 8 is added in the same manner, a single PC pile 6 is inserted and inserted from the soft ground layer 2 to the supporting ground layer 3, and the rear end portion is inserted into the anchor plate 20. Projecting from the mouth 21, the tensile material 7 is also led out from the opening 19.

  Next, as shown in FIG. 1, the grout 5 is press-fitted into the anchor hole 4, and after this is hardened, the tension member 7 led out from the opening 19 is tensioned with a predetermined force to fix the anchor plate 20. The ground anchor 1 is constructed by fixing to the tool 22. The PC pile 6 is improved in adhesion performance with the grout 5 by the circular protrusion 9, and the tensile material 7 is adhered to the grout 5 together with the reinforcing bar 13. The grout 5 is also filled into the steel pipe 17 of the PC pile 6.

  In the above embodiment, the PC trunk 6 is formed by joining the compression trunk body 8 while inserting the compression trunk body 8 into the anchor hole 4, but separately from this, before the compression trunk body 8 is inserted into the anchor hole 4. The PC pile 6 can be formed by joining to the anchor hole 4 and the PC pile 6 can be inserted into the anchor hole 4.

  The ground anchor method using the PC piles 26 and 29 according to the second and third embodiments is also constructed by the same method as described above.

It is sectional drawing of the ground anchor of 1st Embodiment. It is the sectional view on the AA line of FIG. It is the BB sectional view taken on the line of FIG. It is sectional drawing of the front-end | tip part of the ground anchor of 1st Embodiment. It is sectional drawing of the ground anchor of 1st Embodiment. It is sectional drawing of the ground anchor of 1st Embodiment. It is sectional drawing of the ground anchor of 2nd Embodiment. It is sectional drawing of the front-end | tip part of the ground anchor of 2nd Embodiment. It is sectional drawing of the ground anchor of 3rd Embodiment. It is sectional drawing of the front-end | tip part of the ground anchor of 3rd Embodiment. It is sectional drawing of the embankment structure using a ground anchor. It is sectional drawing of the slope using a ground anchor. It is sectional drawing of a ground anchor construction method.

Explanation of symbols

1, 24, 27 Ground anchor 2 Soft ground layer 3 Support ground layer 4 Anchor hole 5 Grout 6, 26, 29 PC pile 7 Tensile material 8, 16 Compression trunk 9 Projection 10, 17, 28 Steel pipe 11 Longitudinal muscle 12 Spiral muscle DESCRIPTION OF SYMBOLS 13 Reinforcement rod 14 Tensile material 15 Steel plate for joining 18 Sheath 19 Opening 20 Anchor plate 21 Insert port 22 Fixing tool 23 Pile body 25 Crimp grip 30 Filling hole 31 Embankment structure 32 Foundation block 33 Retaining wall 34 Slope

Claims (4)

  Prestressed concrete piles are formed by connecting a plurality of compressed trunks with protrusions on the outer periphery and steel pipes in the length direction, and the prestressed concrete piles are formed in the grout at the anchor holes in the ground. The tensile material inserted and wired in the steel pipe, the tip of which protrudes from the tip of the prestressed concrete pile, is led out from the opening of the anchor hole and given a predetermined tension force to the anchor plate fixing tool. A ground anchor characterized by being established.   The ground anchor according to claim 1, wherein a reinforcing bar rod or a steel pipe protrudes from a tip end portion of the compression trunk body installed at the lowermost end portion, and a tensile material is wired in the reinforcing bar rod or the steel pipe. .   A compression trunk having a protrusion formed on the outer periphery and a steel pipe inside is formed, a tensile material is wired in the steel pipe of the compression trunk, and the compression trunk is wired with the tensile material. A plurality of compression trunks are joined to form a prestressed concrete pile, the prestressed concrete pile is inserted into an anchor hole in the ground, and the anchor hole is filled with grout. After the grout is hardened, the anchor hole is opened. A ground anchor method characterized in that a tensile material derived from a portion is applied to a fixing tool of an anchor plate by applying a predetermined tension.   The ground anchor according to claim 3, wherein a reinforcing bar or a steel pipe protrudes from the tip of the compression trunk installed at the lowermost end, and a tensile material is wired in the reinforcing bar or the steel pipe. Construction method.

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