JPS6221088B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for reinforcing retaining walls constructed to prevent the collapse of steps of various sizes formed on land such as cliffs, cut-outs, embankments, or river embankments.

Retaining walls such as cliffs and embankments often collapse naturally due to wind and rain, and it is necessary to protect and reinforce them. For this reason, it is generally necessary to excavate the entire surface of a cliff, embankment, etc. or only at key points and bury the anchor as deep as possible into the soil, or
Alternatively, anchors are driven deep into the soil, and then tension is applied to the anchors to utilize the frictional force generated between the anchors and the earth and sand to prevent the retaining walls from collapsing. However, in this construction method, the stress distribution within the soil layer that is applied by the anchor is maximum at the surface layer, and as it gets deeper, this stress distribution decreases and reaches a value of O or close to it at the end of the anchor. It is clear that a triangular distribution is formed, which requires fairly long anchors to generate sufficient frictional forces. Therefore, as a conventional retaining wall reinforcement construction method, for example, a driving head is fixed at the tip, and a plurality of locking pieces that can be opened and closed by rotation are arranged and fixed on the driving head. Insert the anchor rod, then rotate the anchor rod to expand the locking piece, excavate the surrounding area, inject mortar, concrete, synthetic resin, etc. into the drilled hole to form a lump at the tip of the anchor, and then A construction method was proposed that consisted of applying tension to each anchor that protruded from the retaining wall. However, this construction method requires digging down the embankment and weakening the ground before burying the anchors, making it difficult to construct in areas with densely populated houses and facilities.Also, even if construction is possible, the ground will loosen due to rainwater, etc., and the retaining wall will be damaged. It was unsatisfactory as a reinforcement method for retaining walls because it was easily displaced. In addition, not only a large excavator is required, but a means for rotating the anchor is also required, and the movement of these construction machines on the site impairs work efficiency, and there are problems in that a relatively large construction area is required. Furthermore, we had to devise ways to dispose of the soil that was created by re-drilling holes using the anchor's locking pieces.

The present invention was made to improve the above-mentioned conventional drawbacks, and by using an anchor that has extremely high pull-out resistance, construction can be carried out on soft ground while retaining the bearing capacity, and extremely low Enables quick and economical construction using suitable materials,
The purpose of this invention is to provide a retaining wall reinforcement method that is easy to construct even in densely populated areas with people's homes and facilities.

The basic concept of the present invention is to drive an anchor of a predetermined length with a U-shaped cut into the embankment or cut,
Inject the swelling agent through the upper opening of this anchor,
The expansion pressure causes the U-shaped tongue formed by the cut to stand up, giving the anchor pull-out resistance, and then applying tension to the upper end of the anchor protruding from the retaining wall, thereby improving the stability of the retaining wall. That is.

The structure and operation of the construction method of the present invention will be explained below based on an embodiment shown in the accompanying drawings.

FIG. 1 is an exploded partial perspective view showing an example of an anchor A employed in the present invention. 1 is a cylindrical body made of metal or synthetic resin, and on its peripheral wall,
A plurality of U-shaped cuts 2 whose bases face toward the upper end of the cylindrical body 1 are provided. This cut 2 forms a U-shaped tongue piece 3. This tongue piece 3...
provides pull-out resistance to anchor A as explained below. Note that a hollow prismatic body may be used instead of the cylindrical body as shown. Also, the shape of the cut is not limited to a strict U-shape, for example,
It may be U-shaped, V-shaped, semicircular, etc., and any shape is acceptable as long as its base is directed toward the upper end of the cylinder. Furthermore, the number of cuts is preferably as large as possible as long as it does not significantly affect the strength of the cylindrical body, but it is preferable to provide them as close to the bottom end of the cylindrical body as possible, and it is sufficient to provide them at about three places on the same circumference of the peripheral wall. be. Reference numeral 4 denotes a driving head which is press-fitted into the opening at the lower end of the cylindrical body 1. Driving head 4
The tip has a sharp shape. The anchor A is thus composed of the cylindrical body 1 and the driving head. Note that the lower end opening of the cylindrical body and the driving head may be screwed together in a male and female manner, or the driving head may be formed integrally with the cylindrical body.

As shown in FIG. 2, a plurality of anchors A having such a configuration are inserted into the embankment 7 at an acute angle to the vertical axis of the retaining wall through holes 6 drilled at predetermined intervals in the retaining wall 5.
Drive it in to the desired depth. It is preferable that this anchor A is relatively short when driven into the upper part of the retaining wall 5, and becomes gradually longer towards the lower part. However, the method is not necessarily limited to this method, and long anchors and short anchors may be driven alternately. Also, if the ground is soft, it is preferable to use a long anchor.

Inflating agent 8 is injected from the upper end opening of each anchor A that has been driven in this way to the position where cut 2 is provided. This swelling agent is a mixture of an inorganic compound mainly composed of silicates, a specific organic compound, and water. For example, a mixture of BLISTER (trade name) manufactured by Onoda Cement Co., Ltd. and water can be suitably used.

The injected swelling agent 8 reaches its maximum inflation pressure after approximately 12 to 24 hours have elapsed, and as shown in FIG.
is provided with pull-out resistance. Figure 4 shows tongue piece 3...
FIG. 5 is a partial perspective view of the cylindrical body 1 of the anchor A in an upright state, and FIG. 5 is a sectional view taken along the line X--X of FIG. 4 with the expansion agent removed. Together with the tongue piece 3... standing up, the cut 2... of the cylindrical body 1 of the anchor A...
As the surrounding area expands (enlarged area 9), compressive stress is applied to the surrounding soil layer, causing consolidation.
As a result, a large frictional force is generated between anchor A... and the embankment.

After the expansion of the expansion agent 8 is completed, a closing fitting is attached to the upper end opening of each anchor A projecting from the retaining wall 5, and tension is applied to each anchor A using a tightening means such as a nut. By applying tension in this manner, the tongues 3 are further erected due to the resistance of the embankment, and the pull-out resistance of the anchors A is further increased.

As described above, the reinforcement of the retaining wall by the construction method of the present invention is completed. Note that if the upper end of each anchor A is not preferably exposed from the retaining wall, a surface layer may be coated thereon.

As explained above, according to the construction method of the present invention,
The pull-out resistance of the anchor becomes extremely high due to the erection of the tongue of the anchor due to the expansion pressure of the swelling agent and the swelling around the tongue of the anchor. In addition, the tongue of the anchor further stands up due to the tightening means such as a nut, thereby further increasing the pull-out resistance of the anchor. Therefore, the anchors can be relatively short and small, and the number of anchors can be minimized, and it also provides good stability even for thin retaining walls such as concrete layers made by spraying. can be granted. In addition, there is no need to drill holes for anchor planting, and it is sufficient to simply drive the anchor, so it can be constructed even on soft ground while retaining its bearing capacity. Furthermore, since it is sufficient to make cuts in the surrounding walls of the anchors at the factory and simply drive them in at the site, there is no need for large machines such as excavators, making it easy to move construction machinery at the site, and as a result, temporary scaffolding can be simplified. However, there are no inconveniences in construction, and the construction work is extremely easy. Therefore, the number of on-site workers is reduced, making it possible to save labor and to facilitate and speed up construction even in areas with densely populated houses and facilities.

Although the construction method of the present invention is mainly effective for reinforcing already constructed retaining walls, it goes without saying that it can also be applied to constructing new retaining walls.

[Brief explanation of the drawing]

FIG. 1 is an exploded partial perspective view showing an example of an anchor employed in an embodiment of the present invention, and FIG. 2 is a sectional view showing the anchor driven into embankment through a hole provided in a retaining wall. FIG. 3 is a sectional view showing the state in which the tongue piece formed on the anchor is erected due to the expansion pressure of the expansion agent; FIG. 4 is a perspective view of the main part of the anchor showing the state in which the tongue piece of the anchor is erected;
The figure shows the state in which the swelling agent has been removed.
FIG. 1... Cylindrical body, 2... Cut, 3... Tongue piece, 4...
... Drive head, 5... Retaining wall, 7... Embankment, 8...
Expanding agent, 9... ampullary part.

Claims (1)

[Claims] 1. An anchor consisting of a plurality of U-shaped cuts with the base facing the top of the cylinder on the peripheral wall of the cylinder and a driving head attached to the opening at the bottom of the cylinder is drilled into the retaining wall. The anchor is cast into the soil through the hole, and then an expansion agent is injected through the opening at the upper end of the anchor, and the expansion pressure causes the U-shaped tongue formed by the cut to stand up, giving the anchor pull-out resistance. A retaining wall reinforcement construction method that consists of applying tension to the upper end of the anchor protruding from the retaining wall using a tightening means such as a nut.