JP2015229861A - Metallic ground anchor structure and installation method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metallic ground anchor structure and an installation method therefor that eliminate the need on maintenance and management relating to the structure, that is, achieve so-called maintenance free and prolong the service life, by eliminating the need to supply a rustproof material for corrosion prevention after constructing the ground anchor on a sloped surface, thereby enhancing the anticorrosion property and long-term anchorage property.SOLUTION: A metallic ground anchor has an anchor body part 2, a tension part 3, and an anchor head part 4 formed by a stranded PC steel wire tendon 1 filled and covered with a polyethylene resin. A stainless steel restricting-type spiral spacer 5 is fitted on the anchor body part 2, and a tip of the spiral spacer is covered with a terminal cap 6. The tension part 3 is covered with a polyethylene sheath 7. A stainless steel or a zinc-plated tendon grip 8 is fitted on the anchor head part 4, and a filler 9 that anchors and adheres firmly on the tendon is filled and cured inside the tendon grip.

Description

  The present invention relates to the structure of a metal ground anchor and its installation method, and after constructing the ground anchor on the slope surface, it is not necessary to replenish rust preventives for corrosion prevention, and to achieve corrosion resistance and long-term fixability, It aims at so-called maintenance-free and long life that does not require maintenance related to the structure.

In general, a metal ground anchor that is drilled in the ground of a slope surface and inserted into the drilling hole to prevent the surface layer from collapsing and the rock mass from collapsing has a tensile force applied to a tensile member made of PC steel wire. There is known an adhesion transmission method for transmitting to an anchor body part by adhesion resistance force between a tension member and a grout material.
The structure of the anchor body part of the adhesion transmission method is that when a tensile force is applied to a tensile member made of a strand made of PC steel, a split crack develops in the surrounding grout, so the adhesion part of the tensile member and the grout gradually breaks down, There is a problem that the creep property is pulled out, and the improvement is demanded.
In addition, the structure of the metal ground anchor head is a method in which a tensile member made of PC steel wire is fixed with a wedge and the surrounding area is protected with a rust preventive material and a protective cap, and a steel pipe is pressed on the tensile member. There is known a method in which after screwing, a screw is cut and fixed with a nut, and its periphery is anticorrosive with a rust preventive and a protective cap.
However, when the vicinity of the anchor head is submerged for a long time due to spring water from the ground, it is difficult to block water, and deterioration of the rust preventive material proceeds.
For this reason, in the method of fixing with the wedge, there is a problem that the corrosion of the wire progresses more than the wedge or PC steel, and even when the PC steel strand coated with resin is used, the wedge and the wedge are gripped. Since the resin is broken in the part of the PC steel strand, the progress of corrosion cannot be avoided.
In addition, the method of fixing with the nut has a problem that the corrosion of the screw portion proceeds, and even when stainless steel or the like is used for the screw portion steel pipe, the potential difference between dissimilar metals at the crimping portion with the PC steel strand. Therefore, the progress of corrosion is inevitable.
Therefore, the structure of the metal ground anchor head has a problem with respect to the anticorrosion, and the improvement thereof is required.

  In addition, metal ground anchors installed on the slope surface are required to be maintained and managed against deterioration of anchorage anchorage and corrosion of the anchor head over time, but maintenance and inspection work on steep slope surfaces, etc. Is always dangerous and needs to be improved.

JP 2003-293379 A Japanese Patent Laid-Open No. 08-134907 Japanese Patent Laid-Open No. 06-192980 JP 2004-353343 A

In Patent Document 1, a spiral bar 3 for preventing cracking of concrete is provided on the outer peripheral side of an anchor bar 2, and the spiral bar 3 is a foundation concrete 5 due to a horizontal force F applied to a male threaded rod part 2 a protruding from the base top surface. Embedded in the foundation concrete 5 in a manner that can prevent cracking.
Since the present invention is not concrete, but a hole is provided in a natural ground and an anchor body is inserted therein, the conditions are different.

Patent Document 2 is an adhesion transmission type ground anchor in which a tension member in which a reinforcing bar processed in a spiral shape is attached to the upper part of an anchor body is embedded in a grout material in the ground. In the present invention, a parallel cylindrical spiral spacer is disposed on the entire anchor body, whereas the cylindrical body is processed into a spindle shape and disposed only on the top of the anchor body.
In the present invention, the reason why the spiral spacers are arranged parallel to the anchor body is that, in addition to suppressing the development of split cracks in the grout, the covering for the grout to fill and adhere to the entire tensile material of the anchor body portion. Is to prevent damage to the coating of the wire from the PC steel during construction, and the scope of the purpose and effect is different from Patent Document 2.

In Patent Document 3, polyethylene resin is completely filled and coated inside and outside the PC steel strand that constitutes tendon, and one or two ridges are spiraled on the outer circumference in the diameter direction of the PC steel strand. By forming it into a shape, adhesion with the grout is ensured.
In the present invention, a PC steel strand having excellent corrosion resistance and adhesion is used.

  Patent Document 4 uses a high-strength fiber composite material as a tendon, whereas the present invention uses a PC steel wire as a tendon.

  The present invention is provided to realize maintenance-free and long life of the metal ground anchor.

  In the first aspect of the present invention, in a metal ground anchor, an anchor body portion, a tension portion, and an anchor head portion are formed with a wire tendon from a PC steel filled and coated with a polyethylene resin, and a stainless steel restraint type spiral is formed on the anchor body portion. Fit the spacer, put the end cap on the tip of the spiral spacer, cover the tensile part with a polyethylene sheath, fit the stainless steel or galvanized tendon grip on the anchor head, and against the tendon in the tendon grip A fixing filler having high fixing power and fixing power is filled and cured.

  The second aspect of the present invention is a metal ground anchor manufacturing method, in which a long strand of PC steel filled and coated with polyethylene resin is cut into a predetermined length to make a tendon, and the anchor head is made of stainless steel or galvanized. Fitted with a tendon grip with anti-corrosion effect such as manufacturing, filled with a fixing filler with high fixing power / adhesive strength inside, hardened, covered with a polyethylene sheath on the tension part, stainless steel on the anchor body part A restraint type spiral spacer is fitted and the end cap is covered with a terminal cap.

  In the third method of the present invention, in the metal ground anchor installation method, for the purpose of drilling a drilling length designed by a boring machine on the slope of a natural ground and fixing cement milk that becomes grout in the drilled hole to the ground. After pouring into the ground, insert the ground anchor into the drilling hole, pressurize the cement milk, harden the anchor plate after hardening, and tighten the anchor head to the pressure receiving plate on the slope with a jack through the fixing nut. It is fixed while applying force.

  Since the present invention has the above configuration, the following effects are obtained. That is, according to the structure of claims 1 to 3, the anchor body portion is reinforced by the cylindrical constraining spiral spacer, so that the grout is uniformly filled and adhered to the entire anchor body portion, and the anchor body is inserted into the ground. As a result, the development of splitting of the grout filled and hardened can be suppressed. As a result, the creep resistance can be improved.

Further, the PC steel stranded wire and the surrounding grout of the anchor body portion have an effect of exhibiting higher adhesion than the conventional method by reinforcement by a constraining spiral spacer.
Furthermore, when inserting the metal ground anchor into the drilling hole on the ground slope, the PC steel strand filled and coated with polyethylene resin in the anchor body part is entirely covered with a constraining spacer and protected. So no damage will occur.

  Furthermore, the anchor head is fixed to a stainless steel or galvanized cylindrical tendon grip with a filler for fixing the wire tendon from PC steel filled and coated with polyethylene resin. The gripping part and screw part are not corroded due to deterioration of the rust material or intrusion of moisture, and permanent corrosion resistance is obtained.

In the present invention, with a single metal ground anchor, long-term fixability can be achieved by suppressing the development of splitting of the filled grout and exhibiting a high adhesion function to the grout.
Furthermore, since the permanent corrosion resistance of the tensile member can be obtained, maintenance-free operation and longer service life can be realized without the need for inspection and repair after the metal ground anchor construction.

It is a side view of the ground anchor structure concerning the present invention. FIG. 2 is an enlarged cross-sectional view taken along line 2-2 in FIG. It is an expanded sectional view which follows the 3-3 line of FIG. FIG. 4 is an enlarged cross-sectional view taken along line 4-4 of FIG. It is a figure which shows the test result of the grout adhesion strength with respect to the spiral spacer of an anchor body part.

  The anchor body, tension, and anchor head are formed from PC steel filled and coated with polyethylene resin with a wire tendon, and a stainless steel constraining spiral spacer is sheathed, and a terminal cap is put on the tip, and the tension part is covered. Covering the polyethylene sheath, fitting a stainless steel or galvanized tendon grip to the anchor head, filling and curing the filler with high fixing power and fixing power in the grip, and fixing the anchor head. Therefore, after ground anchors are installed on the slope surface, it is not necessary to replenish rust preventives for corrosion prevention, so that corrosion resistance and long-term fixability are achieved, so-called maintenance-free and long-life maintenance is not required. Can be realized.

1 to 4 show a ground anchor structure according to the present invention, 1 is a line made of tendon PC strand coated with a coating material 1 ₁ polyethylene resin, anchoring body the tendon length, the tension member, the anchor It is composed on the head. The tendon 1 can use a super-durable PC steel strand (for example, “SUPRO \ Supro (registered trademark of Time Engineering Co., Ltd.)”).
2 is an anchor body part, 3 is a pulling part, 4 is an anchor head part, 5 is a stainless steel constraining spiral spacer fitted to the anchor body part 2, 6 is a terminal cap placed on the tip of the anchor body part 2, 7 Is an ambush sheath made of polyethylene that covers the pulling portion of the anchor, and 8 is a tendon grip that is made of stainless steel or galvanized and has an anticorrosion effect, such as a crown, and has one end connected to one end of the anpond sheath 7. It is in contact. 9 is a fixing filler for holding the PC strand of the anchor head filled in the cylindrical cap, 10 is a ground surface of the ground, 11 is a hole drilled from the ground surface into the ground, and 12 is It is a grout filled in the drilling hole, and attaches a wire from the PC steel of the anchor body part to the spiral spacer 5. 13 is a pressure receiving plate, 14 is an anchor plate, and 15 is a fixing nut. The anchor plate 14 and the fixing nut 15 are both made of the same material as the tendon grip 8. Reference numeral 16 denotes a protective cap.

  For the fixing filler 9, a known product is used, for example, a material having a high fixing force / adhesive force such as a cement-based bolt fixing material or an epoxy resin-based bolt fixing material.

  Moreover, the stainless steel restraint type spiral spacer 5 protects the tendon when it is inserted, and further secures the adhesion cover to the grout 12 filled in the drilling hole 11, and prevents the hardened grout 12 from being split. Therefore, the spiral pitch (interval) is set to about 2 to 5 times the filament diameter.

"Production example of ground anchor"
(1) and tendon length 1 line from super durable PC steel coated with a coating material 1 ₁ of the polyethylene resin was cut to a predetermined length.
(2) A tendon grip 8 is fitted to the anchor head 4 and a fixing filler 9 for fixing the tendon head is filled therein and cured.
(3) The unbonded sheath 7 made of polyethylene is put on the tension part 3 of the tendon 1.
(4) A constraining spiral spacer 5 is fitted and attached to the anchor body 2 of the tendon 1.
(5) A terminal cap 6 is put on and attached to the tip of the anchor body 2 of the tendon 1 to complete the ground anchor.

"Specific ground anchor installation process"
(1) A drilling hole 11 is provided by drilling from the ground surface 10 of the natural ground into the ground with a predetermined depth by a boring machine.
(2) Cement milk is primarily injected into the hole 11 as a grout 12 for the purpose of removing slime.
(3) Insert a ground anchor into the hole 11.
(4) Cement milk as the grout 12 is injected into the casing under pressure, and then injected into the secondary injection.
(5) The grout 12 filled in the drilling holes adheres the PC strand of the anchor body part to the constraining spiral spacer 5 with a strong adhesion force. FIG. 5 shows that the adhesion strength is several steps higher than that of the conventional method.
(6) After the grout 12 is cured, the anchor head 4 is fitted with a pressure receiving plate 13 with a hole in the tendon grip 8.
(7) The anchor plate 14 and the fixing nut 15 are fitted into the tendon grip 8 in this order from the top of the pressure receiving plate 13 and fixed to the pressure receiving plate 13. Finally, the protective cap 16 is put on.

  The present invention completely eliminates the occurrence of corrosion by using a stainless steel or galvanized tendon grip and a fixing filler for fixing the head of a wire tendon from a PC steel filled and coated with a polyethylene resin. By fitting a spiral spacer to the body to improve long-term fixability, it can be used as a new ground anchor that has never existed as a maintenance-free, completely corrosion-resistant long-life anchor.

DESCRIPTION OF SYMBOLS 1 ... Tendon made from PC steel coated with polyethylene resin coating material 2 ... Anchor body part 3 ... Tensile part 4 ... Anchor head 5 ... Stainless steel restraint type spiral spacer 6 ... End cap 7 ... Polyethylene sheath 8 ... Made of stainless steel Or galvanized cylindrical tendon grip 9 ... Fixing filler 10 ... Slope 11 ... Hole 12 ... Groat 13 ... Pressure plate 14 ... Anchor plate 15 ... Fixing nut 16 ... Protective cap

Claims (3)

  The anchor body part (2), tension part (3), and anchor head part (4) are formed of wire tendon (1) from PC steel filled and coated with polyethylene resin. The anchor body part (2) is made of stainless steel. The spiral spacer (5) is fitted, and the end cap (6) is put on the tip of the spiral spacer, the polyethylene sheath (7) is covered on the tension part (3), and the anchor head (4) is made of stainless steel or A metal ground anchor characterized in that a galvanized tendon grip (8) is fitted, and a fixing filler (9) having a high fixing force / adhesive strength to the tendon is filled and cured in the tendon grip.   PC steel wire filled and coated with polyethylene resin is cut into a predetermined length to make a tendon (1). A stainless steel tendon grip (8) is fitted to the anchor head, and a high fixing force Filling and fixing the fixing filler (9) having fixing force, covering the tensile part (3) with a polyethylene sheath (7), and anchoring part (2) made of stainless steel constrained spiral spacer (5) A metal ground anchor manufacturing method, characterized in that a terminal cap (6) is put on the end of the tendon. Drilling a drilling length designed by a boring machine on the ground surface, pouring cement milk that becomes grout into the drilling hole for the purpose of fixing to the ground, and then inserting a ground anchor into the drilling hole Furthermore, the anchor plate is attached after the cement milk is hardened by injecting under pressure, and the anchor head is fixed to the pressure receiving plate on the slope surface while applying tension with a jack via a fixing nut. Metal ground anchor installation method.