JPH02279819A - Installation of underground anchor - Google Patents

Abstract

PURPOSE:To simplify work by making blades widely open at the furthermost part of an anchor hole by using bearing metal fixtures with anchor blades capable of widely opening with remote control, and grouting cement grout into the hole to bury the bearing metal fixtures into the hole. CONSTITUTION:Three blades bearing metal fixtures 12 are provided to the center shaft 11 of a center steel pipe of an anchor bearing metal fixture 10, they have anchor blades 13 respectively, and a moving ring 15 is fitted in the axial direction of the shaft 11 so that it is capable of sliding to pivot the lower end of a ring 16 on three projected pieces of the bottom of the ring 15. A flange 24 is provided to the lower end of the center shaft 11 to anchor an anchor tension wire 27 with an anchorage metal fixture 28. The bearing metal fixture 10 is rotated by a boring machine 23 while feeding the jet water into an anchor hole 30 through a steel pipe 23, and an anchor hole 33 with an enlarged diameter is formed in the furthermost part to carry out the injection of cement milk, the laying of the bearing metal fixture 10 and the placement of anchor concrete 32. According to the constitution, even if it is installed shallowly, it can with stand the load of drawing.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an underground anchor installation method for constructing a removal anchor or a permanent anchor mainly used for earth retaining, mountain retaining, etc. of an underground excavation part.

(Prior art) As shown in Fig. 4, a conventional underground anchor is constructed by inserting an anchor tension wire 3 with an anchor bearing fitting 2 fixed to its tip into an anchor hole 1 drilled from the ground surface by poling. Generally, grout made of cement milk is injected into the hole 1 and solidified, and the tip of the anchor wire tension wire 3 is fixed in the anchor concrete 4 of the anchor hole 1.

Furthermore, as shown in FIG. 5, this type of underground anchor is known to have an enlarged diameter portion 1a at the deep end of the anchor hole 1 to increase the resistance against the pull-out load of the anchor concrete 4 from the ground surface. ing.

(Problems to be Solved by the Invention) When installing such conventional underground anchors, the anchor bearing fittings inserted into the anchor hole are of a size that can pass through the small diameter part near the opening of the anchor hole. Since the diameter of the enlarged diameter part cannot be increased very much, it is necessary to make the anchor hole deep in order to obtain a large pull-out load.

As a result, the overall length of the anchor becomes longer, which not only makes it more difficult to excavate and insert the anchor into it, but it also forces the anchor to reach underground on someone else's land.
There was a time when U had to make it possible to remove it, resulting in high costs.

In view of these problems, the present invention aims to provide an underground anchor installation method that can provide a large pull-out load even in a shallow anchor hole and that allows easy insertion of the anchor.

(Means for Solving the Problems) The feature of the underground anchor installation method of the present invention for solving the above-mentioned conventional problems and achieving the intended purpose is that it has anchor blades that can be expanded by remote control. Using an anchor bearing pressure fitting, a steel pipe for operation is connected to the top of the outer anchor bearing pressure fitting, and an anchor tension wire with one end fixed to the anchor bearing pressure fitting is inserted into the steel pipe, The anchor pressure fitting is inserted into an anchor hole excavated from the surface of the ground, the anchor blades are expanded at the innermost part of the anchor hole, and the anchor pressure fitting is rotated through a steel pipe. forming an enlarged diameter anchor hole, injecting cement grout into the enlarged diameter anchor hole, burying an anchor bearing fitting in the enlarged diameter anchor hole with the anchor blades expanded, and removing the steel pipe; The purpose is to lead out the other end of the anchor tension wire to the outside.

(Function) In this underground anchor installation method, by rotating the anchor bearing fitting through the steel pipe with the anchor blade open, an enlarged diameter portion corresponding to the size of the anchor blade is formed, and the expanded diameter portion is It will be buried in the anchor concrete in an open state, and the load in the pullout direction applied to the anchor bearing fitting will be directly applied to a wide area of the anchor concrete via the anchor blades, and the anchor concrete will compress the ground. It will work.

(Example) Next, an example of implementation of the present invention will be described with reference to the drawings.

Figures 1 and 2 show an example of an anchor bearing fitting used in this method. This anchor bearing fitting 10 has a central shaft 11 made of a steel pipe at its center, and the lower end side of each anchor blade 13 is pivotally connected by a pin 14 to three blade supporting fittings 12 that radially project from the outer periphery of the upper end thereof. ing.

A moving ring 15 is fitted into the center of the central shaft 11 so as to be slidable in the axial direction. The upper end of a link 16 is pivotally connected to three protrusions protruding from the lower surface of the movable ring 15 by a pin 17, and the lower end of the link 16 is pivotally connected to the central portion of the anchor blade 13 by a pin 18. There is.

A reinforcing rib 19 is provided radially projecting from the outer periphery of the upper end of the central shaft 11, and a flange 20 is integrally provided at the lower end of the rib. A coil spring 21 is interposed between the flange 20 and the movable ring 15, and biases the movable ring 15 in the dry direction.

A joint cylinder 22 is integrally provided at the upper end of the central shaft 11 inside the reinforcing rib 19, and a steel pipe 23 for operation is screwed into a thread on the inner surface of the joint cylinder 22 for connection. .

A flange 24 is integrally provided on the outer periphery of the lower end section 1 of the central shaft 11, and a bearing pressure plate 26 is fixed below the flange 24 via a support shaft 25. A plurality of through holes are formed in the bearing pressure plate 26, through which the lower end of the anchor tension wire 27 inserted into the central shaft 11 is passed, and is fixed to the lower surface thereof via a fixing metal fitting 28.

Next, the steps of an embodiment of the method of the present invention using the above-mentioned anchor bearing fitting will be explained.

First, using an excavator such as a boring machine or a screw orc, anchor holes 30 having approximately the same diameter are bored over the entire area as shown in FIG. 3(A).

The above-described bearing fitting 10 is inserted into this anchor hole 30 as shown in FIG. 3(B). During this insertion, the coil spring 21 is compressed to fold the anchor blade 13 into a position along the central axis 11, and the steel pipe 23 is connected to the upper end of the anchor blade 23 while being prevented from opening with the string 31. Further, an anchor tension wire 27 made of an unbonded cable is inserted into the steel pipe 23 and the central shaft 11, and the anchor tension wire 27 is inserted with its lower end fixed to the fixing fitting 28. In addition, the opening stop using the string 31 is made so that the tip of the string puller is led out to the ground so that it can be easily removed by pulling the string.

In this way, the bearing fitting 10 and the anchor tension wire 2
7 to the I&M portion of the anchor hole 30, then insert the steel pipe 2
Attach the upper end of 3 to the boring machine 32, and
Pull the upper end of the string 31 to release the lock on the anchor blade 13. At this time, the anchor blade 13 is attached to the coil spring 2.
1 is pushed open via the moving ring 15 and link 16.

In this state, while feeding jet water into the anchor hole 30 through the steel pipe 23, the boring machine 32 moves the bearing fitting 10 up and down and turns it, thereby forming the bore link hole 30 as shown in FIG. 3(C). An enlarged diameter anchor hole 33 is formed in the deepest part of the hole. After that, the steel pipe 23 is pulled out with the bearing fitting 10 positioned at the innermost part of the enlarged diameter anchor hole 33, cement milk is poured into the anchor hole 30.33, and the anchor concrete 34 is cast. A bearing metal fitting 10 is buried inside it to serve as an anchor.

After the anchor concrete 34 has hardened, the anchor tension wire 27 is pulled as shown in FIG.

(Effects of the Invention) As described above, in the underground anchor installation method of the present invention, the bearing fitting having the anchor blades that are expanded in the anchor hole is inserted into the anchor hole having the same diameter over the entire length, and the anchor By opening the anchor blade in the hole and leaving it open, the enlarged diameter part is excavated, and the bearing fitting is buried in the anchor concrete with the anchor blade opened in the enlarged diameter part. This makes it possible to easily construct an underground anchor with a structure that can withstand large pull-out loads even in shallow anchor holes with simple work. In addition, since the tip of the tension wire is fixed to the lowest end of the bearing metal fitting, force acts on the anchor concrete in the compression direction, creating an underground anchor that can withstand larger pull-out loads.

[Brief explanation of drawings]

Fig. 1 is a plan view of the bearing fitting used in the present invention, Fig. 2 is a vertical sectional view of the same portion, Figs. 3 (A) to (D) are sectional views showing the construction process, Figs. Each figure is a cross-sectional view schematically showing a separate conventional earth anchor. 10... Bearing metal fitting, 11... Center shaft,
12...Blade support fitting, 13...Anchor blade, 15...Movement ring, 1''6...
...Link, 20...Flange, 21...
... Coil spring, 22 ... Joint tube, 23 ... Steel pipe, 24 ... Flange, 26 ... Bearing plate, 27 ...・Anchor tension wire rod, 28... Fixture fitting, 30...
・Anchor hole, 31... String, 32...
Boring machine, 33...Diameter expansion anchor hole, 34...Anchor concrete. Patent applicant Kurosawa Construction Co., Ltd.] Figure 5 Figure 4 (D) (C) Figure

Claims (1)

[Claims] An anchor tension wire using an anchor bearing fitting having anchor blades that can be expanded by remote control, connecting a steel pipe for operation to the top of the outer anchor bearing fitting, and having one end fixed to the anchor bearing fitting. is inserted into the steel pipe, the anchor bearing fitting is inserted into the anchor hole excavated from the surface of the ground, the anchor blades are expanded at the innermost part of the anchor hole, and the steel pipe is rotating the anchor bearing pressure fitting through the anchor to form an enlarged diameter anchor hole;
Cement grout is injected into the expanded diameter anchor hole, and with the anchor blades expanded, the anchor bearing fitting is buried in the expanded diameter anchor hole, and the steel pipe is removed, and the other end of the anchor tension wire is An underground anchor installation method characterized by bringing it out to the outside.