JPH0530932B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is used to prevent collapse of earth retaining walls in civil engineering and construction root cutting work, to prevent retaining walls from falling, to prevent buoyancy of dock slabs, to prevent pier piers from falling, and to prevent slopes. This relates to the earth anchor construction method used for stability, etc.

(Prior art) As shown in Fig. 9, the conventional earth anchor construction method involves inserting a tensile steel member C' whose tip protrudes from the sheath into the earth anchor hole A, and at the same time
B' is injected, and after curing the consolidation material B', the tension steel is
C′ was to be fixed by tensioning it with a predetermined tension force.

This earth anchor construction method calculates the design value of the anchor body resistance (pulling shear resistance) by averaging the value over the entire length of the anchor body as shown in a, and then applies a predetermined tension to the tension steel member C′ based on the design value. It was established by giving power.

(Problems to be Solved by the Invention) However, in the above fixing method, when tension force (pulling force) is applied to the anchor body, the stress distribution is concentrated on the front side as shown in FIG. The distribution of body resistance exceeds the design value.

As a result, the ground on the front side of the anchor body is destroyed due to the tension and the creep or elongation of the anchor body over time, and this destruction sequentially moves to the tip side, causing so-called advance failure, and the anchor body comes out of the anchor hole. I had a problem with it.

The purpose of the present invention to solve the above problems is to
When anchoring an earth anchor, the shearing resistance with the ground that occurs when tension is applied to the anchor body is averaged over the entire length of the anchor body in accordance with the design value of the anchor body resistance of the target ground. It is to do so.

(Means for Solving the Problems) The gist of the present invention for solving the above problems is to provide upper and lower retaining plates that are provided with retaining grooves radially and provided at the upper and lower parts of the support; The bearing pressure tool consists of a curved body protruding from the lower surface of the lower hanging plate and around which the tension steel material is wound. The tensioned steel material is inserted into the anchor holes so as to be located at different locations, and a consolidation material is injected into the anchor holes, and after the consolidation material hardens, the tensioned steel materials are sequentially tensed with a predetermined tension force. In particular.

(Function) According to the above configuration, in the earth anchor construction method of the present invention, when three tension steel members of different lengths are attached to the anchor body, the longest first tension steel member with the largest elongation is first installed. , the tension is applied by the difference in elongation from the next longer second tension steel member.

When the first tensioned steel material is tensed by the difference in elongation from the second tensioned steel material, tensioning of the second tensioned steel material is started and the second tensioned steel material is tensioned together with the first tensioned steel material.

Next, when this second tension steel material is tensioned by the difference in elongation from the shortest third tension steel material, tensioning of the third tension steel material is started and the third tension steel material is tensed together with the first and second tension steel materials, and these tension steel materials are By tensioning the tensioned steel material until it reaches a predetermined tension, the shear resistance generated between the anchor body and the ground is averaged over the entire length of the anchor body in accordance with the design value of the anchor body resistance of the target ground. can be applied.

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

In the earth anchor construction method of the present invention, tensile steel members 1 of different lengths each having a bearing pressure device 2 on the tip side are placed in an anchor hole A having a predetermined diameter and length with the bearing pressure devices 2 shifted in position. At the same time as the anchor hole A is inserted, a consolidation material B is injected into the anchor hole A, and after curing the consolidation material B, the tensile steel members 1 are tensed with a predetermined tension force in order of length.

Tension steel material 1 is PC steel wire with polyethylene sheath 3
This is a conventionally well-known device which is slidably inserted into the body through grease, and is bent into a U-shape at the center by a reinforcing bar bender or a hydraulic bender, and the bearing pressure tool 2 is attached to the bent portion 1a.

The bearing pressure tool 2 is formed by an upper hanging plate 5 and a lower hanging plate 5' provided at both upper and lower ends of the support body 4, and a curved body 6 attached to the lower surface of the lower hanging plate 5'. The tension steel material 1 is hung around the U-turn figure.

Latch grooves 8 are provided on the peripheries of the upper and lower latch plates 5, 5' to face each other, and the tension steel material 1 bent into the U-shape is latched to the latching grooves 8. It is fixed to the bearing pressure tool 2 for use as a fixing tool such as the like.

The latching groove 8 is formed to a size that can completely accommodate the entire tensioned steel material 1, and is formed at the same location in both the upper and lower latching plates 5 and 5'.

The bent portion 6 is fitted with the bent portion 1a at the tip of the tensioned steel material 1, and is provided protruding from the center of the lower retaining plate 5'.

As mentioned above, the tension steel material 1 is the first tension steel material 20, the second tension steel material 30, and the third tension steel material 40 in order of length.
The first tension steel material 20, which is formed by assembling the three pieces and is hung around the first bearing pressure tool 20a in a U-turn shape, is inserted into the retaining groove 8 of the second bearing pressure tool 30a and the third bearing pressure tool 40a,
Further, the second tension steel members 20, which are hung around the second bearing pressure tool 20a in a U-turn shape, are respectively fitted into the locking grooves 8 of the third bearing pressure tool 40a and bound with fixing tools m such as tape or wire. It is assembled by

Further, as the consolidation material B, cement paste, mortar, concrete, etc. are used.

In this case, the first, second, and third tension steel members 20, 3
To distinguish between 0 and 40, wrap different colored vinyl tapes around the front side so that you do not mix up the order in which the tension is applied.

In addition, as mentioned above, each tension steel material 20, 30, 40
By hanging them around each other in a U-turn, they can be easily pulled out when they are pulled out, so they can also be used as removal anchors.

Then, tension steel members 1 of different lengths are inserted into the anchor hole A with the bearing pressure tool 2 shifted in position, that is, at different depths, and a consolidation material B such as cement paste, mortar, or concrete is inserted into the anchor hole A.
is injected, and after the consolidation material B has hardened, the tension steel material 1 is tensioned.

This tension is calculated by calculating the elongation of the first, second, and third tension steel members 20, 30, and 40 before starting the tension, and then applying tension to the difference in elongation of each tension steel member 20, 30, and 40. Tension steel material 20, 30, 40
be nervous.

That is, first, the first tension steel material 20, which has the largest elongation, is held between the tensioning heads of the jack and tensioned by the difference in elongation from the second tension steel material 30. At this time, the second and third tension steel members 30 and 40 are not held between the tension heads.

Then, when the first tension steel material 20 is tensed by the difference in elongation with the second tension steel material 30 and the difference in elongation with the second tension steel material 30 disappears, the second tension steel material 30 is It is clamped between the heads and tensioned, and tensioned together with the first tensioned steel member 20.

In addition, the first tension steel material 20 and the second tension steel material 3
The point at which the difference in elongation of 0 is eliminated shall be confirmed by the stroke of the tension rod of the jack.

That is, when the first tensioned steel material 20 is tensioned, the difference in elongation with the preset second tensioned steel material 30 and the elongation difference with the second tensioned steel material 30 disappears when the stroke of the tensioning rod is extended. This is to confirm.

Moreover, this can also be confirmed by a predetermined tension load set in advance.

Next, this second tension steel material 30 is transferred to the third tension steel material 4.
When the elongation difference between the third tension steel material 40 and the third tension steel material 40 disappears, the third tension steel material 40 is clamped between the tensioning heads and tensioning is started. tension steel material 20, 30,
40 is tensioned until it reaches a predetermined tension, and then fixed with the anchor head.

In addition, the time when the difference in elongation between the second tension steel material 30 and the third tension steel material 40 disappears shall be confirmed by the same method as described above.

These first, second, and third tension steel materials 2
After 0, 30, and 40 are fixed under tension, by simultaneously tensioning them with a predetermined tension force,
The total tension of these tension steel materials 20, 30, and 40 can be confirmed.

FIG. 7 shows a case where four pairs of locking grooves 8 are provided in the upper and lower locking plates 5, 5', and in this case, four tension steel members 1 can be assembled.

Moreover, FIG. 8 shows another embodiment of the earth anchor construction method.

This forms first, second, and third tension steel members 20', 30', and 40' of different lengths, each having a bearing pressure portion 2' formed by having the tip of the strand protrude from the sheath, and supports these. The anchor body D is formed by inserting the pressure parts 2' into the cement paste B' so that the pressure parts 2' are located at different points from each other, and tensioned with a predetermined tension force in order from the longer tensioned steel members as described above,
After that, these are simultaneously tightened and fixed with a predetermined tension.

(Effects of the Invention) The present invention has the following effects by having the above configuration.

The shear resistance that occurs between the anchor body and the ground can be averaged over the entire length of the anchor body in accordance with the design value of the anchor body resistance of the target ground, so cracks in the anchor body can be prevented, and It is possible to prevent the earth anchor from coming off even on soft ground.

The support device includes upper and lower retaining plates that are provided with retaining grooves radially and provided at the upper and lower parts of the support, and a curved plate that protrudes from the lower surface of the lower retaining plate and around which the tension steel material is hung. Because it was formed from the body,
Since the tension steel material can be fitted into the locking groove, a large number of supporting pressure tools having the same diameter can be inserted into the anchor hole in a concentric manner.

By sequentially tensioning the tension steel materials, it is possible to tension all the tension steel materials with one tension jack.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the earth anchor construction method of the present invention, Fig. 2 is a perspective view of a tension steel member wrapped around a bearing pressure device in a U-turn shape, and Fig. 3 is an enlarged front view of the bearing pressure device. Fig. 4 is a bottom view of the first bearing pressure device, Fig. 5 is a bottom view of the second bearing pressure device, Fig. 6 is a bottom view of the third bearing pressure device, and Fig. 7 is another implementation of the bearing pressure device. Bottom view showing an example,
FIG. 8 is a sectional view showing another embodiment of the earth anchor construction method, and FIG. 9 is a sectional view showing the conventional earth anchor construction method. In addition, in the figure, A: Anchor hole, B: Consolidation material, 1:
The tension steel materials are shown respectively.

Claims (1)

[Claims] 1. Consisting of upper and lower retaining plates provided with radial retaining grooves and provided at the upper and lower parts of the support, and a curved body that protrudes from the lower surface of the lower retaining plate and around which the tension steel material is hung. Insert tension steel materials of different lengths wound around the bearing pressure tool in a U-turn into the anchor hole so that the bearing pressure tool is located at different locations, and at the same time injecting the consolidation material into the anchor hole. An earth anchor construction method characterized in that the tensioned steel material is sequentially tensioned with a predetermined tension force after the consolidation material has hardened.