JPH011824A - Earth anchor method - 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] <Industrial Application Fields> The present invention is useful for preventing collapse of earth retaining walls, prevention of retaining walls from falling, prevention of buoyancy of dock slabs, prevention of fall of bridge piers, etc. in civil engineering and construction root cutting work. This relates to the earth anchor construction method used.

(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 injecting a consolidation material B'. After curing the consolidation material B', the tension steel material C' was fixed by tensioning it with a predetermined tension force.

In this earth anchor construction method, the design value of the anchor integral resistance (pulling shear resistance) is calculated as a value averaged over the entire length of the anchor body as shown in a, and the predetermined tension is applied 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 (handling force) is applied to the anchor, the stress distribution is concentrated on the front side as shown in FIG. The distribution exceeds the design value of the integral resistance.

As a result, the ground in front of the anchor unit is destroyed due to tension and creep or elongation of the anchor unit over time.
Moreover, there is a problem in that so-called advance failure occurs in which this failure sequentially moves toward the distal end side, and the anchor unit is removed from the anchor hole by one inch.

An object of the present invention to solve the above problems is that when anchoring an earth anchor, the shear stress when tension is applied to the anchor unit is proportional to the design value of the anchor unit resistance of the target ground. This is done by averaging over the entire length.

(Means for Solving the Problems) The gist of the present invention for solving the above problems is to insert tensile steel members of different lengths each having a bearing pressure portion on the tip side into an anchor hole. A plurality of tension steel members are inserted at different positions from each other, and a consolidating material is injected. After curing the consolidating material, these tensile steel members of different lengths are individually tensioned with a predetermined tension force. After that, they are simultaneously tensioned and fixed with a predetermined tension force.

(Function) According to the above configuration, the earth anchor construction method of the present invention, for example, when three tension steel members of different lengths are attached to one anchor, first, the elastic elongation rate of the tension steel members is determined. Tensioning the longest tensioned steel material with a predetermined force,
When the elongation rate becomes the same as the elongation rate of the next longer tension steel material, the tension steel material is tensioned with a predetermined force.

Then, in the same way as above, when the elongation rate of the two tension steel materials becomes the same as the elongation rate of the shortest tension steel material, tensioning of the tension steel materials is started, and the tension is continued until a predetermined tension is reached. do.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

In the earth anchor construction method of the present invention, tensile steel members C- of different lengths each having a bearing pressure part 2 on the tip side are inserted into an anchor hole of a predetermined diameter and length with the bearing pressure parts shifted in position. At the same time, the consolidation material B is injected, and after curing the consolidation material B, the tension steel materials C are tensed at a predetermined tension in order of length, and then they are simultaneously tensioned at a predetermined tension and fixed. It is something to do.

The tension steel material C is composed of a tension strand 1 and a bearing pressure part 2, and the tension strand 1 is a conventionally well-known structure in which the strand 1b is slidably inserted into a polyethylene sheath 3 via grease, and is made by a reinforcing bar bender. It is bent at the center, and a bearing pressure portion is formed at the bent portion 1a.

The bearing pressure part 2 is a hanging plate 5 provided at both the upper and lower ends of the support body 4.
．． 5' and a curved body 6 attached to the lower surface of the retaining plates 5, 5-, a bearing member 7 is attached to the bent portion 1a of the tension strand 1.

A latching groove 8 is provided on the peripheral edge of the latching plate 5.5- to face each other. It is temporarily fixed, and a fixing device 1 such as tape or wire is wound around the bearing pressure device 7 to fix it.

The retaining groove 8 is formed to a size that completely accommodates the entire tension strand 1, and is formed at the same location on both the upper and lower sides.

The bending body 6 is fitted with the bent portion 1a at the tip of the tension strand 1, and is provided protrudingly from the center of the lower hanging plate 5'.

As mentioned above, the tension steel material C is the first tension steel material 20 in order of length,
The second tension steel material 30 and the third tension steel material 40 are assembled and formed.
151 of the first tension steel material 20 in a state where 0a is shifted toward the front side by an appropriate distance from the first bearing pressure tool 20a of the first tension steel material 20.
By fitting the 4 tension strand 20b into the locking groove 8 of the second support pressure tool 30a, and fastening the 1511 tension strand 20b to the second support pressure tool 30a with the fixing tool 1 such as tape or wire, The second tension steel material 30 is attached to the first tension steel material 20 and assembled. Further, the third tension steel material 40 is also
Similarly to the tension steel material 30, the third bearing pressure tool 4 of the third tension steel material 40
The first tension strand 20b and the second tension strand are fitted into the locking groove 8 of the third pressure support shell 40a with the tension strand 0a shifted toward the front side by an appropriate distance from the second pressure support tool 30a, and these first Tension strand 20b and second tension strand 30
b with a fixing device such as tape or wire to the third bearing pressure device 30a.
The third tension strand 40 is attached to the second tension strand 30 by tightening to form an assembly.

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

In this case, the first, second and third tension strands are 20°30.
To distinguish each 40, wrap different colored vinyl tape around the front side so that you do not mix up the order in which they are strained.

Furthermore, by forming each tension strand in a U-shape as described above, it can be easily handled when pulling out the strand 1b, so that it can also be used as a removal anchor.

As described above, the tension steel members C having different lengths are inserted into the anchor hole Δ with the bearing pressure portions shifted in position, and the consolidation material B such as cement paste, mortar, and concrete is injected.

Next, after curing the consolidation material B, the first tension strand 20 which has the highest elongation rate with respect to the tension force is tensed by a tension jack J, and the tension force is applied to the third tension strand 20 which has the second highest elongation rate. 30, start tensioning the second tension strand 40, and while tensioning these first and second tension strands, the tension of the second tension strand 30 has the next highest elongation rate. When the elongation rate of the third tension strand 40 becomes the same as that of the third tension strand 40, tensioning of the third tension strand 40 is started, and these first, second, and third tension strands 20.3
0.40 is tightened and fixed until a predetermined tension is reached.

FIG. 8 shows a case in which four pairs of locking grooves 8 are provided in the locking plate 5, and in this case, four tension steel members can be assembled.

Moreover, FIG. 9 shows another example of actual drops of tension steel material C-.

This forms first, second, and third tension strands 20'', 30'', and 40= of different lengths in which bearing pressure portions 2' are formed by making the tips of the strands protrude from the sheath, and
These are inserted into the cement paste B- so that the bearing pressure parts 2' are located at different points from each other to form an integrated anchor, and the tensioned steel members are tensioned with a predetermined tension force in order from the longer tensioned steel members as described above. After that, they are simultaneously tightened and fixed with a predetermined tension.

(Effects of R-light) The present invention has the following effects by using the construction method as described above.

■ It is possible to average the shear stress that occurs in the entire anchor when tensioning the tension strand in the tension steel material with a predetermined tension force over the entire length of the anchor in proportion to the design value of the anchor resistance of the target ground. This prevents the earth anchor from coming off when placed on soft ground.
B) Since the shear stress generated in the anchor can be averaged over the entire length of the anchor in proportion to the design value of the anchor resistance of the target ground, the earth anchor can be anchored with tension suitable for each type of ground. This can increase its reliability.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of the present invention, Fig. 2 is a perspective view, Fig. 3 is an enlarged front view of the fixing device, Figs. 4 to 6 are a bottom view of the same, and Fig. 7
The figure is a bottom view of another embodiment of the fixing device, FIG. 8 is a longitudinal sectional view of another embodiment, and FIG. 9 is a longitudinal sectional view of a conventional example. In addition, in the figure, A: anchor hole, B: spun material, C: tension 14 material. are shown respectively.

Claims (1)

[Claims] A plurality of tensile steel members of different lengths each having a bearing pressure portion on the tip side are inserted into the anchor hole with the bearing pressure portions being shifted to different positions, and a consolidation material is injected, and the consolidation material is After curing, these tensioned steel members of different lengths are individually tensioned with a predetermined tension, and then they are simultaneously tensioned and fixed with a predetermined tension.