JP5546422B2 - Ground anchor construction method - Google Patents

Description

  The present invention relates to a ground anchor construction method. Specifically, the present invention relates to a ground anchor construction method for constructing a ground anchor for fixing a foundation of a structure to the ground.

Conventionally, when a structure is constructed in a place where groundwater is high, in order to prevent the structure from being lifted by groundwater, a ground anchor may be provided downward from the foundation of the structure in the vertical direction (Patent Document 1). reference).
Such a ground anchor is constructed in the following procedure, for example. First of all, we will conduct mountain construction and pile construction, and then construct a work platform and excavate while lowering the groundwater level by discharging the groundwater through the deep well.

  When the excavation work is completed, a drilling machine is installed on the floored surface and drilled vertically downward by this drilling machine. Next, a tensile material is inserted into the drilled hole, and an injection material is injected into the hole. After that, the foundation is constructed, and the tensile material is fixed on the constructed foundation.

However, the above method has the following problems.
Since the ground anchor is constructed after the excavation work is completed, construction of the foundation of the structure cannot be started until the construction of the ground anchor is completed. In addition, since the hole drilling machine is installed on the flooring surface, a part of the hole drilling machine interferes with the braces of the work gantry, and it takes time to remove and restore the braces and move the hole drilling machine. Therefore, there was a problem that the construction of the frame was prolonged.

In addition, when the ground anchor is installed, the deep well is in operation, so even if the grout material is injected into the hole, the grout material may be sucked into the deep well and flow out of the hole. It was difficult to control the quality of the materials.
In addition, since the deep well is operated over the period of construction of the ground anchor, the operation period of the deep well is prolonged and the original groundwater level is higher than the construction position of the ground anchor. It was necessary to use a water stop box.
Therefore, there was a problem that the construction cost increased.

  In order to solve the above problems, a method of constructing a ground anchor from the ground surface before excavation has been proposed (see Patent Document 2). Specifically, in order to construct an underground structure by the reverse driving method, ground anchors are constructed on the ground surface. Next, a structure is constructed, tension is introduced into the tensile material, and the upper end side of the tensile material is fixed to the ground level structure. Then, while excavating, build the underground frame.

According to the method disclosed in Patent Document 2, since the ground anchor is constructed on the ground surface before excavation, construction of the foundation can be started immediately after the excavation work is completed, and the drilling machine interferes with the work gantry. There is no need to do so, so the time required for frame construction can be shortened.
Further, since it is not necessary to operate the deep well when constructing the ground anchor, the injected material injected into the hole is not sucked into the deep well, and the quality control of the injected material is easy. Moreover, since the groundwater level becomes lower than the construction height of the ground anchor, it is not necessary to attach a water stop box or the like. Therefore, it can suppress that construction cost rises.

JP 2008-223432 A JP 2002-70044 A

  However, in the method disclosed in Patent Document 2, since the excavation is started after the tensile force is introduced into the tensile material, it is necessary to perform excavation while paying attention to the tensile material into which the tensile force is introduced. There was a risk of becoming.

  An object of this invention is to provide the ground anchor construction method which can shorten the period of a frame construction and excavation construction, and can suppress that a construction cost raises.

The ground anchor construction method according to claim 1 is a ground anchor construction method for constructing a ground anchor for fixing a foundation of a structure to the ground, and drilling a hole in a ground surface before excavation for constructing the foundation. Preparing a jig comprising a process, a tubular main body, and a substantially U-shaped engagement portion provided on the main body, and locking one end side of the tensile material to the main body; Attaching the one end side to the hook of the crane, inserting the other end side of the suspension wire into the engagement portion and attaching the suspension wire to the hook, and connecting the tension wire and the suspension wire; Lifting the tensile material using the hole, inserting the tensile material into the drilled hole, injecting the injection material into the hole to fix the tip side of the tensile material to the ground, and other than the suspension wire Remove the end from the hook Raising the hooks, and characterized by comprising a step of recovering the suspension wire, a step of building a foundation and excavation to the floor with surface, to fix the base end side of the tension member to the foundation, the To do.

  According to this invention, since the ground anchor is constructed on the ground surface before excavation, construction of the foundation can be started immediately after completion of the excavation work, and the drilling machine does not interfere with the work gantry. The construction period can be shortened.

  Further, since it is not necessary to operate the deep well when constructing the ground anchor, the injected material injected into the hole is not sucked into the deep well, and the quality control of the injected material is easy. Moreover, since the groundwater level becomes lower than the construction height of the ground anchor, it is not necessary to attach a water stop box or the like. Therefore, it can suppress that construction cost rises.

  Further, since the suspension wire is collected, the wires do not become an obstacle during excavation work, so that the excavation work period can be shortened. In addition, the construction cost can be reduced by collecting and reusing the hanging wire.

Here, the ground anchor construction method according to claim 1, wherein the tensile member and the suspension wire is provided with a cylindrical body, and the engaging portion of the substantially U-shape provided in the body, the Connected with a jig .

  According to this invention, when inserting a tensile material into the hole, for example, the proximal end side of the tensile material is attached to the main body of the jig, and one end side of the suspension wire is attached to the hook of the crane. Next, the other end side of the hanging wire is inserted into the engaging portion of the jig and then attached to the hook. Next, the tensile material is lifted by a crane, and the tensile material is inserted into the hole. As a result, it is possible to remove only the suspension wire from the hole by simply removing the other end side of the suspension wire from the hook and lifting the suspension wire, so that the suspension wire can be easily recovered with a simple mechanism.

The ground anchor construction method according to claim 2 is characterized in that a foundation of the structure has a foundation beam, and the foundation anchor is provided so as to pass near the beam center of the foundation beam in a plan view.

In the past, the side of the foundation beam was blown up, and a ground anchor was provided on the blown up part. Therefore, there has been a problem that the foundation beam is enlarged and the construction cost is increased.
However, according to the present invention, since the ground anchor is provided so as to pass through the vicinity of the beam center of the foundation beam in plan view, it is not necessary to blow the foundation beam as in the conventional case, and it is possible to suppress an increase in construction cost.

  According to the present invention, since the ground anchor is constructed on the ground surface before excavation, the construction of the foundation can be started immediately after the excavation work is completed, and the drilling machine does not interfere with the work gantry. The construction period can be shortened. Further, since it is not necessary to operate the deep well when constructing the ground anchor, the injected material injected into the hole is not sucked into the deep well, and the quality control of the injected material is easy. Moreover, since the groundwater level becomes lower than the construction height of the ground anchor, it is not necessary to attach a water stop box or the like. Therefore, it can suppress that construction cost rises. Further, since the suspension wire is collected, the wires do not become an obstacle during excavation work, so that the excavation work period can be shortened. Moreover, since the suspension wire can be collected and reused, the construction cost can be reduced.

It is sectional drawing of the ground anchor to which the ground anchor construction method which concerns on one Embodiment of this invention was applied. It is a top view of the ground anchor concerning the embodiment. It is FIG. (The 1) for demonstrating the construction procedure of the ground anchor which concerns on the said embodiment. It is a side view which shows the state which lifted the tendon of the ground anchor which concerns on the said embodiment with the crane. It is FIG. (2) for demonstrating the construction procedure of the ground anchor which concerns on the said embodiment. It is FIG. (3) for demonstrating the construction procedure of the ground anchor which concerns on the said embodiment. It is a figure (the 4) for demonstrating the construction procedure of the ground anchor which concerns on the said embodiment. It is a figure (the 5) for demonstrating the construction procedure of the ground anchor which concerns on the said embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of a permanent anchor 1 as a ground anchor to which a ground anchor construction method according to an embodiment of the present invention is applied. FIG. 2 is a plan view of the permanent anchor 1.

The permanent anchor 1 is provided to fix the foundation of the structure to the ground. The permanent anchor 1 is provided at predetermined intervals on the beam center of the foundation beam 2 in plan view. The permanent anchor 1 extends vertically downward from the foundation beam 2.
Specifically, a hole 3 is formed vertically downward from the foundation beam 2, and a tendon 10 is inserted into the hole 3. The bond portion 14 </ b> A of the tendon 10 is fixed to the ground, and the steel wire 14 extending upward from the tendon 10 is fixed to the foundation beam 2 by the fixing tool 4.

  The fixing tool 4 is mounted on the upper surface of the foundation beam 2 and through which the steel wire 14 passes, the support plate 5 through which the support plate 5 is engaged with the support plate 5, an unillustrated locking claw, and a steel wire 14 and a cap 6 attached to the upper end of 14.

  Hereinafter, a portion of the permanent anchor 1 that is fixed to the ground is referred to as a fixing length portion 7, and a portion that is not fixed to the ground is referred to as a free length portion 8.

The permanent anchor 1 is constructed in the following procedure.
First, as shown in FIG. 3, the drilling machine 20 is arranged on the ground surface before excavation. This drilling machine 20 is, for example, a rotary percussion self-propelled type in which a drilling machine and an injection device for injecting a grout material are integrated.
With this hole drilling machine 20, a casing 21 is inserted into the ground surface, and a hole 3 is formed by drilling to a predetermined depth with a cutting blade (not shown) at the tip of the casing 21.

FIG. 4 is a side view showing a state where the tendon 10 is lifted by a crane.
As shown in FIG. 1, the tendon 10 is provided on the inner peripheral side in the vicinity of the distal end portion of the sheath tube 11 and a sheath tube 11 made of synthetic resin (for example, a corrugated tubular corrugated sheath) having irregularities on the inner and outer peripheral surfaces. A first water stop material 12, a second water stop material 13 provided on the inner peripheral side in the vicinity of the base end of the sheath tube 11, and a plurality of pipes that penetrate the second water stop material 13 and are accommodated in the sheath tube 11. A steel wire 14 (for example, a PC steel stranded wire) as a tensile material, an inner injection pipe (not shown) that extends through the second water-stopping material 13 to the vicinity of the distal end portion in the sheath tube 11, and a second water-stopping material 13 and the first water blocking material 12, and an outer injection tube 15 having a distal end protruding from the distal end of the sheath tube 11.

  The proximal end side of the steel wire 14 is covered with a coating material (not shown). A portion of the steel wire 14 that is not covered with the covering material is referred to as a bond portion 14A, and a portion that is covered with the covering material is referred to as an unbonded portion 14B.

Here, the jig 30 is prepared. The jig 30 includes a cylindrical main body 31 and a substantially U-shaped annular engagement portion 32 attached to one end side of the main body 31.
In addition, a suspension wire 23 having a predetermined length is prepared. One end of the suspension wire 23 is locked and has an annular shape, and the other end is fixed with a wire clip 25 to have an annular shape.

One end side of the suspension wire 23 is attached to the hook 22 of the crane, and the other end side of the suspension wire 23 is inserted into the engaging portion 32 of the jig 30 and attached to the hook 22.
Further, the steel wire 14 exposed from the upper end of the tendon 10 is bent, the steel wire 14 is inserted into the main body 31 of the jig 30 from below, and the bent portion is locked to the main body 31. In this way, the tendon 10 and the suspension wire 23 are connected by the jig 30.

  Thereafter, as shown in FIG. 5, the tendon 10 is lifted by a crane, and the tendon 10 is inserted into the casing 21.

  Next, an injection device (not shown) of the drilling machine 20 is driven, and a grout material as an injection material is injected from the injection device into the sheath tube 11 through the inner injection tube, and the sheath tube 11 is filled. And cure.

  As a result, the steel wire 14 of the bond portion 14A is fixed to the sheath tube 11 via the grout material, and the coating material is interposed between the steel wire 14 of the unbond portion 14B and the sheath tube 11, so that the sheath tube 11 It can be freely expanded and contracted.

  As shown in FIG. 6, the tendon 10 is lowered to the bottom of the hole 3. In this way, the bond portion 14 </ b> A of the steel wire 14 is made to reach the fixing length portion 7. At this time, the pipe 24 made of a small diameter vinyl chloride is inserted into the hole 3 until it comes into contact with the upper end of the tendon 10 to check the depth of the tendon 10.

  Next, while pulling out the casing 21 from the hole 3 while injecting the grout material into the bottom of the hole 3 below the first water stop material 12 through the outer injection pipe 15 from the injection device (not shown), The grouting material is filled in the gap between the inner peripheral surface of the hole 3 and the outer peripheral surface of the sheath tube 11. At this time, by confirming the height position of the tube 24 inserted into the hole 3, it is confirmed that the tendon 10 does not rise together when the casing is pulled out.

  Next, the pipe 24 made of vinyl chloride is pulled out and taken out from the hole 3. Then, the wire clip 25 of the hanging wire 23 is removed, and the other end side of the hanging wire 23 is removed from the hook 22. In this state, the suspension wire 23 is pulled up by the crane. Then, as shown in FIG. 7, the suspension wire 23 is taken out from the hole 3 while the tendon 10 and the jig 30 are disposed in the hole 3.

  Since the sheath tube 11 is formed in a tubular shape having irregularities on the inner and outer peripheral surfaces, the sheath tube 11 is firmly fixed to the inner peripheral surface of the hole 3 via a grout material. As a result, the fixing length portions 7 of the plurality of steel wires 14 are fixed on the fixing ground.

  As shown in FIG. 8, while assembling the work gantry, excavation to the floored surface is performed to expose the steel wire 14 extending from the upper part of the tendon 10.

  Subsequently, the foundation beam 2 is constructed, a jack (not shown) is attached to a portion of the steel wire 14 protruding upward from the upper surface of the foundation beam 2, and a predetermined number of steel wires 14 are attached to the plurality of steel wires 14 by the operation of the jack. A tension force is applied, and in this state, the upper end of the steel wire 14 is fixed to the foundation beam 2 by the fixing tool 4.

According to this embodiment, there are the following effects.
(1) Since the permanent anchor 1 is constructed on the ground surface before excavation, the construction of the foundation beam 2 can be started immediately after the excavation work is completed, and the drilling machine 20 does not interfere with the work gantry. The construction period can be shortened.
Further, since it is not necessary to operate the deep well when constructing the permanent anchor 1, the grout material injected into the hole 3 is not sucked into the deep well, and the quality control of the grout material is easy. Moreover, since a groundwater level becomes lower than the construction height of the permanent anchor 1, it is not necessary to attach a water stop box. Therefore, it can suppress that construction cost rises.

  Further, since the suspension wire 23 is collected, the wires do not become an obstacle during excavation work, so that the excavation work period can be shortened. In addition, the construction cost can be reduced by collecting the suspension wire 23 and reusing it.

  (2) Only the suspension wire 23 can be taken out from the inside of the hole 3 simply by removing the other end side of the suspension wire 23 from the hook 22 and lifting the suspension wire 23. Therefore, the suspension wire 23 can be easily recovered with a simple mechanism.

  (3) Since the permanent anchor 1 is provided so as to pass through the vicinity of the beam center of the foundation beam 2 in plan view, it is not necessary to blow the foundation beam as in the conventional case, and the increase in construction cost can be suppressed.

  It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.

1 ... Permanent anchor (ground anchor)
DESCRIPTION OF SYMBOLS 2 ... Foundation beam 3 ... Hole 4 ... Fixing tool 5 ... Supporting plate 6 ... Cap 7 ... Fixing length 8 ... Free length 10 ... Tendon 11 ... Sheath pipe 12 ... 1st water stop material 13 ... 2nd water stop material 14 ... Steel wire (tensile material)
DESCRIPTION OF SYMBOLS 15 ... Outer injection pipe 20 ... Hole cutter 21 ... Casing 22 ... Hook 23 ... Hanging wire 24 ... Vinyl chloride pipe 25 ... Wire clip 30 ... Jig 31 ... Main body 32 ... Engagement part

Claims (2)

A ground anchor construction method for constructing a ground anchor for fixing the foundation of a structure to the ground,
Drilling holes in the ground surface before excavation for constructing the foundation;
A jig provided with a cylindrical main body and a substantially U-shaped engaging portion provided on the main body is prepared, and one end side of the tension material is locked to the main body, and one end side of the hanging wire is Attaching to the hook of the crane, inserting the other end side of the suspension wire into the engagement portion and attaching to the hook, thereby connecting the tension member and the suspension wire;
A step in which the hanging lifting the tensile member using a wire, inserting the tension member to the drilling pores,
Injecting an injection material into the hole and fixing the tip side of the tensile material to the ground;
Removing the other end side of the hanging wire from the hook, and pulling up the hook to collect the hanging wire;
A ground anchor construction method comprising: excavating to a floor surface to construct a foundation, and fixing a base end side of the tensile material to the foundation. The foundation of the structure has foundation beams;
2. The ground anchor construction method according to claim 1, wherein the ground anchor is provided so as to pass near the beam center of the foundation beam in plan view .

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