JPH0452806B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention provides a ground anchor B for preventing a high-rise building or a tower-like building _A1 as shown in FIG. 7 from falling during an earthquake or a storm. ₁
As shown in Figure 8, when a building A2 with a deep underground part is constructed in a place where the groundwater level W is relatively high, it can be used as a ground anchor _B2 to prevent floating by groundwater, or as a ground anchor _B2 to prevent floating by groundwater, or as shown in Figure 9. As shown in Figure 3, it relates to ground anchors that can be effectively used as ground anchors _B3 to prevent uneven earth pressure or sliding in buildings built on slopes, such as _A3 , and more specifically, 100 ground anchors for permanent installation. This invention relates to a permanent ground anchor that has been improved to have a service life of more than 20 years.

Conventional technology Conventionally, as shown in Figure 7, for high-rise buildings _A1 that require measures to prevent falling during earthquakes and storms,
Even if it was not necessary, this problem was dealt with by adding a deeper underground structure (a) underground.

Furthermore, as shown in Figure 8, building _A2 , which requires measures to prevent surfacing due to groundwater W, has been dealt with by increasing the weight of the building frame.

Furthermore, as shown in Figure 9, building _A3 , which requires countermeasures against uneven earth pressure and sliding, has been dealt with by methods such as scraping away the ground on the mountain side and constructing a retaining wall c.

This is because until now, permanent ground anchors have not been found that are sufficiently reliable in terms of quality and service life.

Conventionally, a wide variety of so-called temporary ground anchors have been used to support retaining walls such as sheet piles and to be removed after use.

For example, FIG. 10 shows the main parts of a temporary ground anchor described in Japanese Unexamined Patent Publication No. 57-13686.

In the figure, e is a tensile steel material, and a bearing plate f is attached to its tip, and a load-bearing body g made of reinforced mortar or the like is brought into contact with the front side of this bearing plate f. It is fixed in the ground by injection material h. The ground anchor described in Utility Model Publication No. 61-8120 has almost the same structure.

Problems to be Solved by the Invention () Although the purpose is to prevent falls during earthquakes and strong winds, it is necessary to purposely attach an unnecessary underground structure part a as shown in Figure 7, or to prevent it from floating up. However, as shown in Figure 8, it is necessary to increase the weight of the building frame A ₂ , or to remove the retaining wall by scraping the ground as shown in Figure 9, even though it is a countermeasure against uneven earth pressure and sliding.
Countermeasures such as building a new one are too short-sighted and have no solution, and are also wasteful and uneconomical solutions.

() Despite the fact that temporary ground anchors are well known and have many practical examples, the reason why they have not been able to be used as permanent ground anchors for permanent installations that can be used as a countermeasure against () above is simply because they are not suitable for rust prevention. This is because they did not have sufficient trust.

For example, even in the case of the temporary ground anchor shown in Fig. 10, the attachment means j between the tension steel e and the bearing plate f remain exposed, and if this is corroded and damaged,
At that point, its useful life as a ground anchor is over.

Additionally, anti-rust coated PC steel stranded wire is normally used for tensile steel e, but if the sheath is damaged or damaged due to some kind of accident during construction or due to deterioration over time during use, the PC Since the wire begins to corrode from the steel, it is impossible to expect a long service life of 10 or 20 years in any case, and it is impossible to expect quality and reliability as a permanent ground anchor for permanent installation. I couldn't get it.

The ground anchor described in Utility Model Publication No. 61-8120 has a first layer attached to the tip of the tensile material by removing the coating layer.
An anchoring steel pipe is attached by crimping, and a circular plate with a slightly larger diameter and a second anchoring steel pipe are brought into contact with the pull-out side of the first anchoring steel pipe.
The fixed steel pipe is directly coated with injection material, which poses a problem in terms of rust prevention. Considering the function, in the case of the ground anchor described in the above publication, the load of the tensile material is:
The first anchoring steel pipe constitutes a stress transmission mechanism in which a part of the stress is directly transmitted to the ground through the injection material, and the rest is transmitted from the second anchoring steel pipe to the ground through the injection material. Therefore, there is a risk that the injection material will crack or break at the boundary between the first anchored steel tube and the second anchored steel tube, where the directions of stress are different, and this poses a problem in terms of strength.

Means for Solving the Problem (First Invention) As a means for solving the problems of the prior art described above, the permanent ground anchor of the present invention has a preferred embodiment shown in FIGS. 1 to 6 of the drawings. As shown, the bearing plate 2 is attached to the tip of the tensile steel material 1 with a grip 13, and the crimp grip 13 and the tip of the tensile steel material 1 are attached in an oil-tight structure to the side opposite to the pull-out side of the bearing pressure plate 2 and coated with rust preventive oil 10. protected by a tip cap containing the

A tubular load-bearing body 3 is brought into contact with the pull-out side of the bearing pressure plate 2 so as to surround the outer periphery of the tensile steel material 1, and the load-bearing body 3 also surrounds the outer periphery of the tensile steel material 1 on the pull-out side of the load-bearing body 3. In this arrangement a tubular free length sheath 4 is abutted.

The outer circumferences of the load-bearing body 3 and the free length sheath 4 are filled with injection material 5 and coated.

A prestress of a predetermined magnitude is introduced into the tensile steel material 1, the upper end of the tensile steel material 1 is fixed on the head bearing plate 12 on the frame 6, and the fixed portion and the upper end of the tensile steel material 1 are Each of them is characterized in that it is protected by a head cap 25 which is attached to the upper surface of the head bearing pressure plate 12 in an oil-tight structure and contains rust preventive oil 24.

Function: In the case of this permanent ground anchor, the bearing plate 2 and crimp grip 13 at the tip, as well as the tip of the tensile steel member 1, are double protected against rust by the tip cap 9 and antirust oil 10.

Further, the free length portion and the fixed length portion of the tensile steel material 1 are also provided with double anti-corrosion protection by the unbonded sheath covering the tensile steel material 1 and the free length portion sheath 4 or the load bearing body 3, respectively.

Moreover, if the covering thickness of the injection material 5 is taken into account, the tip, fixed length, and free length are each treated with triple anti-corrosion protection.

Further, the upper end of the tensile steel member 1, its anchoring portion, and the head bearing plate 12 are connected to the head cap 25 and the rust preventive oil 24.
Anti-corrosion protection is provided.

Thus, the rust protection of this permanent ground anchor is complete over the entire length of the tensile steel 1.
It is safe to say that it has a rust-proof structure with sufficient residual capacity, aiming for a service life of 100 years or more, and you can expect quality and reliability for permanent installation.

In addition, in the case of this permanent ground anchor, the tensile steel member 1 has a completely unbonded structure over the entire length from the position of the bearing pressure plate 2 at the tip to the bearing pressure plate 12 at the head. Since the displacement characteristics during testing are numerically clear and easy to confirm, there are almost no design errors.

Furthermore, in the case of this permanent ground anchor, since steel is used for the load-bearing body 3, its material properties are clear and it is highly reliable.

Moreover, since the structure is such that a reaction force is exerted on the ground by hardening the bond between the load-bearing body 3 and the injection material 5, the anchor frame formed by the injection material 5 acts as a compression type, has good strength, and has no risk of cracking. , it has an excellent service life.

(Second Invention) As a means for solving the same problem, the permanent ground anchor of this invention is also provided in the first aspect of the drawings.
As shown in the embodiments shown in FIGS. 6 to 6, the entire structure of the first invention is the main part, and the upper end of the free length sheath 4 is a head sheath provided in the anchor opening of the building frame 6. 7, a structure is added in which the damper 8 is slidably inserted into the damper 8.

Effects Therefore, this invention also exhibits the effects described in the first invention. Moreover, in the case of this permanent ground anchor, the tensile steel 1 is double protected against rust by sealing with the free length sheath 4, head sheath 7, and damper 8 in addition to the unbonded sheath at the part where the tensile steel material 1 passes through the frame. has been done.

Furthermore, in the case of this permanent ground anchor, the subsidence of the ground that occurs with the construction of the building's superstructure can be
By sliding the head sheath 7 and the free length sheath 4, complete absorption is achieved over a wide range. In addition, the damper 8 also prevents misalignment between the frame 6 and the ground during an earthquake.
It functions as a so-called bottle structure and exhibits flexibility and flexibility in absorbing liquid flexibly.

Embodiment Next, a preferred embodiment of the present invention shown in FIGS. 1 to 6 of the drawings will be described.

Number 1 in Figure 1 is a wire stranded with about 17 unbonded PC steel, which is tensile steel. By the way, this ground anchor is buried to a depth of about 20m directly under the frame 6, so the PC steel stranded wire 1 has such a length.

A support plate 2 made of a thick-walled cast steel disk is attached to the tip of the PC steel strand 1 with sufficiently high pull-out strength by a crimp grip 13 fixed to the tip of the strand 1.

The bearing plate 2 has a tip cap 9 having approximately the same diameter as the bearing plate 2.
is attached to the anti-pulling side of the bearing plate 2 in an oil-tight structure by welding, and the end cap 9 is filled with Procoat oil 10 as a rust preventive oil.
The attachment part of the steel stranded wire 1 has been subjected to rust prevention treatment.

On the other hand, on the pull-out side of the bearing pressure plate 2, the outer diameter is
86, length is 6m (this length will be the anchor length),
Rib 11 with a wall thickness of about 10 mm that increases adhesion to the outer surface
The cast steel tubular load-bearing body 3 formed with a large number of
It is abutted so as to surround the outer periphery of the steel stranded wire 1, and the abutting portion is watertightly joined to the bearing plate 2 by welding the entire circumference.

Further, on the pull-out side of the load-bearing body 3, the outer diameter is
76. The free length sheath 4, which is made of a gas pipe or the like and has a wall thickness of about 4 mm and is long enough to reach the frame 6 (this length becomes the free length), is also made of PC steel and extends around the outer periphery of the wire 1. They are abutted in a surrounding manner in a concentric arrangement.

The free length sheath 4 is also watertightly joined to the load bearing body 3 by welding the entire circumference. Since the free length sheath 4 has a large total length (more than 10 m), it is constructed by sequentially jointing gas pipes each having a unit length of about 3 m.

The upper end of the free length sheath 4 is slidably fitted by several tens of centimeters into the head sheath 7 installed in the anchor opening of the body 6 via a damper 8. The damper 8 is used to ensure airtightness and watertightness inside and outside the sheath.

Note that each of the above-mentioned components is completely assembled in advance on the ground. Then, as shown in FIG. 2, the fixing hole 14 is hoisted by a crane or the like and inserted into the center of the fixing hole 14, which has been drilled in the ground 15 and the drilling water has been replaced with cement milk 5 as the injection material.
Therefore, the PC steel stranded wire 1 is never exposed to cement milk 5 or its moisture during construction.

After the insertion, the cement milk injection hose 17 is connected to the casing pipe 16 left in the fixing hole 14 in advance (Fig. 3), and while pulling up the casing pipe 16, the length of the load bearing body 3 is removed. Cement milk 5 is press-fitted into the area to form a dense filling.

After pulling out the casing pipe 16, the construction of the frame 6 is completed (Fig. 4), a prestress corresponding to a design load of, for example, 100 tons is introduced by jacking up, and then the anchor head is fixed and rust prevention treatment is performed. (Figure 5).

As shown in FIG. 1, the detailed structure is such that a head bearing plate 12 is placed on the frame 6, an anchor head 18 is installed on top of the head bearing plate 12, and the upper end of the PC steel stranded wire 1 is attached to a wedge 19. and is fixed to the anchor head 18.

This tension fixing work is carried out by using the jack 20 shown in FIG. 6 and by a controlled setting method of the so-called strong hold construction method.

That is, the temporary bearing pressure plate 2 is placed around the outer periphery of the anchor head 18.
1 and set the jack 20 on it,
The upper ends of the steel strands 1 are gripped by the wedge 22 in the jack, each steel strand 1 is simultaneously tensioned, and a pretress of a predetermined size is introduced (FIG. 6 shows the introduced state). Thereafter, the fixing wedge 19 is pushed downward by the index plate 23 to forcibly fix the image.

Therefore, since the problem of loosening of the jack 20 and the PC steel stranded wire 1 does not occur at all, it is possible to introduce prestress with an accurate value. After completing each of the above steps, the jack 20 is removed.

Thereafter, a head cap 25 filled with grease 24, which is a rust preventive oil, is mounted on the head support plate 12 in an oil-tight manner so as to cover the upper end protrusion of the PC steel wire 1.

Although the above example shows a design load of 100 tons, it is easily possible to implement a permanent ground anchor of 200 tons by appropriately designing the sizes of the main members.

Effects of the present invention As described above in detail in conjunction with the examples, the permanent ground anchor of the present invention maintains a necessary and sufficient service life (quality and reliability of anti-corrosion treatment) for permanent installation. For example, anchors to prevent high-rise buildings from falling over (Figure 7), anchors to prevent buildings from floating due to groundwater (Figure 8), or anchors to prevent uneven earth pressure and sliding on buildings (Figure 7). 9), and can be applied to meet various permanent ground anchor needs that arise for other permanent structures.

Therefore, compared to conventional methods that could not use this type of anchor, construction can be carried out extremely easily and great economical and architectural technical effects can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view conceptually showing the overall structure of the permanent ground anchor according to the present invention, Figs. 2 to 5 are important construction process diagrams of the anchor, and Fig. 6 is an explanation of the tension anchoring work. Figures 7 to 9 are explanatory views of the use of the ground anchor, and Figure 10 is a sectional view showing the main parts of a conventional temporary anchor.

Claims (1)

[Claims] 1. A bearing plate 2 is attached to the tip of the tensile steel material 1 with a crimp grip 13, and the crimp grip 13 and the tip of the tensile steel material 1 are installed in an oil-tight structure on the opposite side of the bearing plate 2 from being pulled out. Tip cap 9 containing rust oil 10
A tubular load-bearing body 3 is in contact with the pull-out side of the bearing pressure plate 2 in a position surrounding the outer periphery of the tensile steel material 1,
The tensile steel material 1 is also provided on the pull-out side of the load-bearing body 3.
A tubular free length sheath 4 arranged to surround the outer periphery of the
The outer peripheries of the load-bearing body 3 and the free length sheath 4 are filled with and coated with injection material 5. A prestress of a predetermined magnitude is introduced into the tensile steel material 1, and the same The upper end of the tensile steel material 1 is fixed on the head bearing pressure plate 12 on the frame 6, and the fixing part and the upper end of the tensile steel material 1 are attached to the upper surface of the head bearing pressure plate 12 in an oil-tight structure and coated with rust preventive oil 24. Permanent ground anchors each characterized by being protected by a head cap 25 containing a. 2 Tensile steel material 1 described in claim 1
A permanent ground anchor characterized by being unbonded PC steel stranded wire. 3. Ribs 1 are provided on the outer circumferential surface of the load-bearing body 3 described in claim 1 to increase the adhesion force with the injection material 5.
A permanent ground anchor characterized in that 1 is formed. 4 A pressure bearing plate 2 is attached to the tip of the tensile steel material 1 with a crimping grip 13, and the pressure bonding grip 13 and the tip of the tensile steel material 1 are attached in an oil-tight structure to the side opposite to the pull-out side of the bearing pressure plate 2 and contain rust preventive oil 10. Tip cap 9
A tubular load-bearing body 3 is in contact with the pull-out side of the bearing pressure plate 2 in a position surrounding the outer periphery of the tensile steel material 1,
The tensile steel material 1 is also provided on the pull-out side of the load-bearing body 3.
The upper end of the free length sheath 4 is in contact with the head sheath 7 provided in the anchor opening of the frame body 6 via the damper 8. The outer peripheries of the load-bearing body 3 and the free length sheath 4 are filled and coated with an injection material 5. A prestress of a predetermined magnitude is introduced into the tensile steel material 1. The upper end of the tensile steel material 1 is fixed on the head bearing plate 12 on the frame 6, and the fixing part and the upper end of the tensile steel material 1 are attached to the upper surface of the head bearing pressure plate 12 in an oil-tight structure to prevent rust. Permanent ground anchors each characterized in that they are protected by a head cap 25 containing oil 24.