JPH01165818A - Execution for preparing permanent ground anchor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention is useful for fixing high-rise buildings or tower-like buildings so that they do not fall down due to earthquakes or strong winds, or for fixing underground buildings in places where the groundwater level is relatively high. Permanent J is used to prevent buildings with deep parts from rising to the surface due to groundwater, or to prevent sliding due to uneven earth pressure acting on buildings built on slopes.
'! ! Regarding the construction method of ground anchors, in particular, the anchor assembly is buried at a desired depth in the ground prior to ground excavation, and after the ground is excavated, tension is applied to the tensile steel of the anchor assembly that protrudes from the bottom of the excavation. This invention relates to a method of constructing a permanent ground anchor, which is characterized by introducing a permanent ground anchor and making it work as a permanent ground anchor.

BACKGROUND OF THE INVENTION Conventionally, many so-called temporary ground anchors for supporting retaining walls such as sheet piles have already been put into practice (see, for example, the one described in Japanese Patent Publication No. 13686/1986).

However, there is still no practical example of a full-scale permanent ground anchor, and development research is still in progress. Therefore, the reality is that there is no established construction method.

■ The permanent ground anchor described in Japanese Patent Application Laid-Open No. 62-228521 uses a heavy steel pipe for the free length sheath, and a tensile steel pipe disposed inside the free length sheath and the load-bearing body, and The structure is completely separate from the cement milk and other injection materials that are injected into the hole, and this permanent ground anchor is installed by bringing a hole drill or tow truck to the bottom of the excavation after excavating the ground. It has been implemented.

Problems to be Solved by the Invention A long permanent ground anchor assembly with a total length of 20 m to 30 m is assembled lying horizontally on the ground at the site, and then directly hung by a tow truck or the like. It is lowered and inserted into the hole for construction.

However, since the ground at the bottom of the excavation is rough and the footing is poor, and there are various harmful objects such as struts and superstructures, it is difficult to install a hole drill or a tow truck by lowering it to the bottom of the excavation.
In addition to being time-consuming and difficult, it also poses various obstacles to the free operation of machinery.

For example, in a place where the site is narrow, it is not possible to assemble a long anchor assembly in a straight position, or to secure enough space to hang it up in a straight position.
There is a problem with poor workability.

Therefore, if possible, there is a strong desire to install a permanent ground anchor in the ground before excavating the ground.

However, when adopting and implementing such a construction method, it is important to avoid hindrance to subsequent ground excavation, and to avoid as much waste and uneconomical equipment as possible during the excavation process.

Means for Solving the Problems As a means for solving the problems of the above-mentioned prior art, a method for constructing a permanent ground anchor according to the present invention is provided in the first part of the drawing.
As shown in preferred embodiments in Figures to Figure 15, a) a step of drilling a hole 23 of a predetermined depth into the 1#A plate 20 from the original ground surface with a hole drill 21 using a casing pipe 22; (1) Injecting and filling the injection material 15 into the grooved hole 23 from the bottom of the hole using the grout hose 25.

c) Assemble the anchor assembly 24 on the ground, attach a temporary suspension jig 31 to the upper end of the tensile steel member 10, and removably connect a unit length steel rod 33 to this temporary suspension jig 31; Thereafter, the anchor assembly 24 is inserted into the hole 23 to a predetermined depth while adding the steel rod, and 2) the pressure head 37 is connected to the upper end of the casing pipe 22, and the casing pipe 22 is gradually inserted. By injecting the injection material 15 under pressure while pulling it up, an anchor anchoring portion is formed in the large diameter root portion 38. After that, the casing pipe 22 is completely pulled out, the steel material 33 is removed from the temporary suspension jig 31 and recovered, and (e) the ground 20 is excavated, and the tensile steel material 10 of the anchor cradle integral 24 protruding from the excavated bottom surface 20' is removed. After the construction of the structural frame 16, a predetermined tension force is introduced into the same structural frame 16, and then the head cap 1 is covered to perform rust prevention treatment.

The structure consists of:

Since the anchor assembly 24 is buried on the original ground surface free from any obstacles, construction efficiency can be improved.

Anchor assembly 24 can be installed at any desired depth (
18! (below the bottom surface 20').

After the anchor assembly 24 is installed, the casing pipe 22 and steel rod 33 have been completely recovered and removed, so that the ground 20 can be excavated as before without any obstacles.

There is no wastage of equipment.

After excavating the ground 20, a predetermined tension is applied to the tensile steel member 10 of the anchor assembly 24 protruding from the bottom surface 20' of the excavation, and then it is fixed to the structural frame 16 and subjected to anti-corrosion treatment, so that it can be used as a permanent ground anchor. ), and the service life is no different from that of the conventional example, which is constructed at the excavation bottom surface 20'.

Example Next, a detailed explanation of the illustrated invention will be given.

Figures t51 to 1O show important process diagrams of the permanent ground anchor construction method according to the present invention.

First, Figure 1 shows the original J'I! of the ground 20 to be constructed. ! This shows a stage in which a hole fi 21 such as a rotary percussion drill is installed on the surface of the board, and a hole 23 for fixing the anchor is drilled by a hollow method using a casing pipe 22.

In Figure 2, a grout hose 25 is inserted into a drilled hole 23 (actually a casing pipe 22), and an injection material 15 such as cement milk is injected into the bottom of the hole and replaced with drilling water. It shows the steps to take.

Next, FIG. 3 shows a step in which the anchor assembly 24, which has been assembled on the ground, is vertically suspended by a wire rope 30 such as a crane and inserted into the hole 23.

This anchor assembly 24, as shown in detail in FIG.
Tensile steel barrel unbonded PC steel stranded wire 1
0, a thick-walled steel tubular load-bearing body 11 that transmits the tension force transmitted to the tip bearing plate 12 to the surrounding ground and takes a reaction force, and a structural frame constructed from the upper end of the load-bearing body 11 on the excavation bottom surface. 16
(Fig. 1θ)
The free length sheath 9 is made of a thin-walled (approximately 4 to 5 tm) synthetic resin pipe such as polyethylene and covers the pipe. The crimp grip 13 at the tip is double rust-proofed by a tip cap 17 fixed to the tip support plate 12 and a rust-preventing filler such as rust-preventing oil injected into the tip cap 17 . Further, the upper end of the free length sheath 9 is closed with a lid 18 made of foamed polystyrene or the like to protect the wire lO from PC steel.

The reason why the free length sheath 9 of this anchor assembly 24 is made of a synthetic resin pipe is as follows. The anchor assembly 24 is assembled in a horizontal position on the ground. After that, either lift it up vertically using a tow truck or the like and insert it, or when lifting it up, make sure that the free length sheath 9 is
There is no problem with bending when hoisting it up, and the work can be done smoothly.

However, the free length sheath 9 may be made of a steel pipe as in the past. In this case, since the steel pipe is heavy, there is no fear that it will float up due to the buoyancy of the injection material 15 when inserted into the drilled hole 23. However, it is heavy when lifted by a tow truck, and
The drawback is that the free length sheath 9, which extends to the length of the lofim, often bends when being lifted up.

, the anchor assembly 24 having the configuration L is attached to the wire rope 30.
The same anchor assembly 2 is inserted into the hole 23 by hanging
Temporary hanging jig 31 is attached to the wire lO from the PC steel protruding from the upper end of 4.
is attached, and a wire rope 30 is hung around it.

As shown in FIGS. 12 to 14, the details of the structure of the temporary hanging jig 31 are as shown in FIG. The wire lO is fixed to the PC steel by inserting the wedge 31b. A wedge holding plate 31d with a nut 31c welded to the center of the upper surface is placed on the wedge 316 by passing the wire 1O11o from PC steel and tightening it by passing the plate 31b through the wire 1O from PC steel and tightening the nut 31c. This tightening is performed from the plate 31e to the lifting head 31a.
For tightening, the wedge 31b is pushed in by screwing in the bolt 31f, and due to its pressing effect, the lifting head 31a is firmly attached to the wire 10 by the PC steel. Therefore, the temporary hanging jig 31 can be easily removed from the PC steel stranded wire 10 by loosening and removing the bolt 31f.

Next, FIG. 4 shows that at the beginning of the insertion process of the anchor assembly 24, a temporary support material 32 is installed on the upper end of the casing pipe 22, and the support of the anchor assembly 24 is temporarily transferred to the temporary support material 32. Next, the wire rope 30 is removed from the temporary suspension jig 31, a steel rod 33 of unit length (3 to 4 m) is attached to the temporary suspension jig 31, and the hanging point is changed to the steel rod 33. There is. For details, as shown in FIGS. 12 to 14, a thread is formed at the lower end of the steel rod 33, and the threaded portion is screwed into the nut 31c of the temporary suspension jig 31 to be detachably connected. ing. In other words, the steel rod 33 can be removed from the temporary suspension jig 31 by turning it in the opposite direction.

After changing the hanging point to the above steel bar 33, the temporary support is made of material 3.
2 is removed, and the process of inserting the anchor assembly 24 begins in earnest.

At this time, the anchor assembly 24's free length sheath 9 is made of a lightweight synthetic resin pipe. The tallow hose 34 is inserted deeply into the free length sheath 9 of the anchor assembly 24 and the hollow part of the load bearing body 11 so as to reach the tip bearing plate 12. Then, the injection material 15 such as cement milk is injected and filled into the load-bearing body 11 and the free length sheath 9, and the weight 1 is increased while the insertion is carried out.

FIG. 5 shows a step in the process of inserting the anchor assembly 24 by successively adding unit length steel rods 33. Further, FIG. 6 shows a stage in which the anchor assembly 24 has been inserted to the target depth.

The addition of the steel rod 33 is carried out by threaded connection using a connecting nut 34, as shown in detail in FIG. In addition, in order to prevent the steel rod 33 and the temporary suspension jig 31 from rotating together when separating the steel rod 33 and the temporary suspension jig 31, which will be done later, a locking pin or locking pin (3) is provided.
Fix it with screws 5.

Next, FIG. 7 shows a pressure head 36 attached to the upper end of the casing pipe 22 after completing insertion of the anchor assembly 24.
The casing pipe 22 is pulled up to about 1/2 (about 3 m) of the anchor fixing length (approximately the total length of the load-bearing body 11), and the grouting material 15 is poured through the grout hose 37.
This shows a stage in which a large-diameter root portion 38 is formed by performing pressurized injection and expanding the hole wall ground with the injection pressure. The formation of the large-diameter root portion 38 is completed by further pulling the casing pipe 22 to one end of the fixing length 1 and performing the second stage of pressurized injection. The load-bearing body 11 takes a reaction force to the surrounding ground through this large-diameter root portion 38.

FIG. 8 shows a stage in which the casing pipe 22 has been completely pulled out and the steel rod 33 has also been separated from the temporary suspension jig 31 and recovered. Therefore, there are no obstacles to the excavation of the ground 2o, and the excavation can be carried out in the conventional manner. Further, in excavating the ground 20, no anchor equipment other than the injection material 15 is wasted, making it highly economical.

The 9th UA is Jl! ! The excavation of the board is progressing! i! Bottom surface 2
0' shows a stage where the PC steel stranded wire IO of the anchor assembly 24 protrudes. At this stage, the temporary hanging jig 31
To tighten, loosen the bolt 31f and remove it.

In Figure 1O, a structural frame 16 is constructed on the bottom surface 20' of the excavation, a predetermined tension is introduced into the PC steel stranded wire IO, and the wire is fixed on the structural frame 16, and the head cap 1 is attached. This shows the stage at which the permanent ground anchor has been completed by applying anti-rust treatment to the PC steel protruding from the structural unit 16.

Tension force is introduced into the PC steel stranded wire 10 by a control setting method of the so-called strong hold construction method using a strong hold jack (not shown). A rust preventive filler such as rust preventive oil or cement milk is injected into the head cap L through an injection port provided at a relatively lower position of the cap L, and the filler is filled up to the air hole at the top of the cap. The air present in the head cap l is successively expelled by injecting the anti-rust filler, so that the PC steel strands 10 and the fixing fittings are in complete contact only with the anti-rust filler.

The effects of the present invention are as described above in conjunction with the embodiments, and the method of constructing a permanent ground anchor according to the present invention is fl! ! Board 20
As a step before completing all 20, the anchor assembly 24 is buried in advance at a predetermined depth underground from above the field surface.
Construction can be carried out on a wide, thick ground surface with no obstacles, and the workability is good.

Furthermore, after the anchor assembly 24 is buried at a predetermined depth in the ground, not only the casing pipe 22 but also the steel rod 33
Since all of the anchor equipment is collected and removed, there is no waste of anchor equipment and it is highly economical. And J′l! ! Since no obstacles are created in the excavated part of the board 20, the excavation work can be carried out simply by the conventional method.

After excavating the ground FB 20, the anchor assembly 24 protruding from the excavated bottom surface 20' can be recovered by removing the temporary hanging jig 31 from the PC steel wire 1O and being used for other purposes, making it economical. expensive. The protruding PC steel stranded wire IO can be fixed to the structural frame 16 by applying tension after the structural frame 16 is constructed, and can be moved once as a permanent ground anchor, so it has high practical value.

[Brief explanation of the drawing]

Figures 1 to 10 are explanatory diagrams showing the important steps of the anchor construction method according to the present invention, Figure 11 is an overall structural diagram of the permanent ground anchor to be constructed, and Figure 12 is a temporary suspension of the anchor head. A detailed view of the structure of the jig, FIGS. 13 and 14 are views taken from arrows 13-13.14 to 14 in FIG. 12, and FIG. 15 is a detailed view of the joint of the steel rod. 20...Ground 20'...Excavation bottom surface 21
... Drilling hole a 15 ... Injection material 23.
... Hole 38 ... Large diameter root 33 ... Steel rod 31 ... Temporary hanging jig 10 ... Tensile steel material 9 ... Free length sheath 1 ... Head cap 16 ... Structure Frame (concrete) Figure 10

Claims (1)

[Scope of Claims] [1] A) Using the casing pipe (22) with the hole drilling machine (2)
1) drilling a hole (23) of a predetermined depth into the ground (20) from the original ground level, and b) using a grout hose (25) into the hole (23) to pour the injection material from the bottom of the hole. c) assembling the anchor assembly (24) on the ground;
Attach a temporary hanging jig (31) to the upper end of the tensile steel material,
A unit length steel rod (33) is removably connected to this temporary suspension jig (31), and the anchor assembly (24) is inserted into the hole (23) to a predetermined depth while adding steel rods. d) installing a pressure head (3) at the upper end of the casing pipe (22);
6), and while pulling up the casing pipe (22) step by step, the injection material (15) is injected under pressure to form an anchor anchoring part at the large diameter root (38), and then the casing pipe (22) is
22) are all pulled out, and the steel rod (33) is attached to the temporary hanging jig (31).
), and e) the ground (20) is excavated, and the tensile steel (10) of the anchor assembly (24) protruding from the bottom of the excavation (20') is used to construct the structural frame (16). Later, after introducing a predetermined tension force, it is fixed to the same structural frame (16), and then the head cap (1) is attached.
A method of constructing a permanent ground anchor, which is characterized by comprising the steps of applying rust prevention treatment by covering the ground with.