JPH0412774B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an anchor installation method.

<Conventional technology> When installing an anchor in the ground, a hole-drilling machine is positioned at the tip of the casing pipe as shown in Figure 3, and the hole is drilled while supplying water into the hole, and the casing pipe is then pulled out. There is an anchor installation method in which a tensile member is inserted into a hole, mortar is injected, and after the mortar is cured and hardened, a predetermined tensile force is applied to the tensile member.

The anchor installed in this way transmits the tensile force acting on the tensile material to the mortar and further to the ground, increasing the pull-out resistance of the anchor.

However, when installing an anchor in a solidified mudstone layer, the powder generated during drilling forms a smooth thin film layer on the surface of the hole wall using the water in the hole as a medium. .

Therefore, since a smooth layer is interposed between the mortar and the hole wall, the frictional resistance between the mortar and the hole wall is reduced.

Therefore, the pull-out resistance of the anchor decreases, and the strength of the anchor decreases.

Therefore, we are currently trying to solve the above problems using the following methods.

(1) A method in which a cutter is attached to the tip of the casing pipe, a hole is drilled to a specified depth, the casing pipe is slid inside the hole, and the membrane is removed using the cutter.

However, this method is time-consuming because the membrane at the bottom of the hole is scraped off by sliding the casing pipe many times.

(2) A method in which drilling is performed by supplying air without supplying water into the hole, and does not generate a film of powder using water as a medium.

With this method, there is no water in the hole, so there is a risk that a lot of dust will be generated during drilling, polluting the environment, and the casing pipe will become clogged, making drilling difficult.

<Objective of the present invention> The present invention was made in order to solve the above-mentioned problems, and provides an anchor installation method that can increase the pull-out resistance of the anchor and improve the strength of the anchor. The purpose is to

<Configuration of the Present Invention> An embodiment of the present invention will be described below with reference to the drawings.

<A> Apparatus of the present invention In the present invention, as shown in FIG. 1, a water jet is used.

An injection bit 2 is attached to the end of the guide tube 1 on the bottom side of the hole, and a jet hose 3 connected to the water jet main body is passed through the guide tube 1 and connected to the injection bit 2.

The guide tube 1 serves as a handle for vertically and rotationally moving the injection bit 2 within the hole.

Therefore, in order to make it possible to carry out the work easily by hand, the guide tube 1 is made of, for example, a thin and light tube made of plastic.

The injection bit 2 may be, for example, a cylindrical block made of steel.

A plurality of injection ports 21 are provided on the side surface of the injection bit 2 to spray water or the like toward the hole wall.

The end of the jet hose 3 on the bottom side of the hole is inserted into the injection bit 2 from the upper surface of the injection bit 2, and the tip thereof is closed.

The jet hose 3 located inside the injection bit 2 is connected with the same number of branch pipes 31 as the injection ports 21.
The free end of the branch pipe 31 is attached to the injection port 21.

<B> Anchor installation method (1) Excavation of the ground First, as shown in FIG. 3, the hole-drilling machine 5 is positioned at the lower end of the casing pipe 4 to drill an anchor hole in the ground, as in the conventional method.

At this time, water is injected into the hole through the inner rod, and is discharged to the outside of the hole through the space between the inner rod and the casing pipe 4 together with the excavated earth and sand.

After drilling the hole to a predetermined depth, the drilling machine 5 is removed from the hole.

(2) Inserting the injection bit into the hole Next, as shown in Fig. 1, pull up the casing pipe 4 by a length L from the bottom of the hole.

The length of this L is the length of the fixing length portion.

Then, the injection bit 2 configured as described above is inserted to the bottom of the hole.

(3) Injection of water, etc. From the water jet, for example, 300Kg/cm ²
Water or a mixture of water and granules is sprayed with a water pressure of .

Water or the like passes through the jet hose 3 in the guide tube 1 and is injected from the injection port 21 toward the hole wall.

At this time, the guide tube 1 is moved up and down by a length L from the hole bottom, and is also rotated.

As a result, the injection bit 2 moves up and down and rotates between the fixing lengths, making it possible to roughen the hole wall only between the fixing lengths by spraying water or the like.

(4) Installation of the anchor body After roughening the hole wall and completely removing the thin film of excavation powder, insert the tensile material 6 into the hole as shown in Figure 2, and inject mortar 7 into the anchor length. .

After the mortar 7 is cured and hardened, a predetermined tensile force is applied to the tension member 6 and it is fixed with an anchor head.

<Other Embodiments> In addition to the purpose of spraying water or the like to roughen the hole wall as in the previous embodiment, it is also possible to further increase the force of the spray to enlarge the anchor hole.

<Effects of the Present Invention> Since the present invention has been described above, the following effects can be expected.

<B> By spraying water, etc. onto the hole wall of the fixing length using a water jet, it is possible to completely remove the thin smooth film formed by water and powder during drilling that adheres to the hole wall. .

Therefore, the frictional resistance between the mortar and the hole wall increases, and the resistance to pulling out the anchor increases.

Therefore, the strength as an anchor is improved.

<B> Furthermore, the hole wall can be formed into an uneven shape by spraying water or the like, or the hole wall can be formed into a screw groove shape by moving the injection bit up and down while rotating.

Therefore, the mortar and the hole wall engage with each other, further increasing the frictional resistance, and improving the strength of the anchor.

<C> The injection bit is attached to the lower end of the guide tube.

Since the guide tube is a light and thin tube that can be easily operated manually, by vertically moving and rotating the guide tube, the injection bit can also be easily vertically moved and rotated.

Therefore, it is possible to easily remove the film attached to the hole wall.

[Brief explanation of drawings]

Figure 1: An explanatory diagram of an embodiment of the present invention, Figure 2:
Explanatory diagram of mortar injected into the hole, 3rd
Figure: Explanatory diagram of the hole drilling method.

Claims (1)

[Claims] 1. Drilling an anchor hole in the ground with a hole-drilling machine attached to the lower end of the casing pipe, pulling out the casing pipe after drilling the hole, positioning a tensile material in the hole, injecting mortar, and pouring mortar into the hole. In the anchor installation method, which applies a predetermined tensile force to the tensile material after curing and hardening, after drilling a hole in the ground to a predetermined depth, only the anchored length of the casing pipe is pulled out, and the waterjet injection bit is inserted. A method for installing an anchor, which comprises inserting the anchor to the bottom of the hole, jetting water or the like from the jet bit toward the hole wall, and giving the jet bit vertical and rotational movement between the fixing length parts.