JPS6218687B2 - - 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, cliffs,
Either excavate the entire surface of the embankment or only key points and bury the anchor as deep as possible into the soil, or drive the anchor deep into the soil and then apply tension to the anchor to connect it to the soil. The retaining wall was prevented from collapsing by utilizing the frictional force generated between the walls. However, in this construction method, the stress distribution within the soil layer acted on by the anchor is maximum at the surface layer, and as it gets deeper, this stress distribution decreases and reaches a value of 0 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 to the driving head. The anchor rod is inserted into a drilled hole, and then this anchor rod is rotated to excavate the area around it using the expanded locking piece, and then mortar, concrete, or synthetic resin is injected into the drilled hole to form a lump at the tip of the anchor. A construction method was proposed that consisted of forming a retaining wall and then applying tension to each anchor that protruded from the retaining wall. However, this construction method also requires digging down the embankment and weakening the ground before burying the anchors, making it difficult to construct in areas with densely populated homes and facilities.Also, even if construction is possible, rainwater may loosen the ground and cause the retaining wall to displace. However, this method was not sufficient as a reinforcement method for retaining walls. Moreover, not only a large excavator is required, but also means for rotating the anchor is required, and movement of these construction machines on the site impairs work efficiency, and a relatively large construction area is also required. This posed a problem in that the number of days and costs required for construction would be enormous, especially when the height of the retaining wall was several meters or more than 10 meters.

The present invention has been made to solve the above-mentioned conventional problems, and by using an anchor that has significantly large pulling resistance, supporting force, and frictional force, it maintains ground bearing capacity even on soft ground. It can be constructed quickly and economically using extremely small amounts of materials even for retaining walls several meters in height or more than 10 meters in height, and can even be constructed in densely populated areas with people and facilities. The purpose is to provide an easy retaining wall reinforcement method.

The basic concept of the present invention is to drive a hollow anchor of a predetermined length with a U-shaped cut and a substantially straight cut into the embankment or cut, and inject an expanding agent from the upper end opening of the anchor. Then, the expansion pressure causes the U-shaped tongue formed by the U-shaped cut in the anchor to stand up, and the area around the substantially straight cut increases in size, thereby imparting pull-out resistance, supporting force, and frictional force to the anchor. This method attempts to improve the stability of the retaining wall by applying tension to the upper end of the anchor that protrudes from the retaining wall.

Hereinafter, the structure and operation of the construction method of the present invention will be explained 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 U-shaped cut 21 with the base facing the upper end of the cylinder 1, a U-shaped cut 31 with the base facing the lower end of the cylinder 1, and a substantially linear cut along the longitudinal direction of the cylinder 1. A plurality of 4 and 4 are provided respectively. These U-shaped cuts 21..., 31 form U-shaped tongue pieces 22..., 32.... As will be explained below, the tongue pieces 22 mainly provide the pulling resistance force,
The tongue pieces 33... impart a supporting force to the anchor A, and the cuts 4... impart a frictional force to the anchor A. Note that instead of the cylindrical body shown in the figure, a hollow prismatic body may be used for the anchor body. Furthermore, the shape of the cut is not limited to a strict U-shape, and may be, for example, a square shape, a square shape, a V shape, a U shape, a semicircle, etc., as long as its base faces the top or bottom of the cylinder. Its shape does not matter. The substantially linear cuts 4 may be provided parallel to the axis of the cylindrical body 1, or may be provided along the circumference of the cylindrical body. Furthermore, although the U-shaped cuts 21..., 31... and the substantially straight lines 4... are provided alternately along the longitudinal direction of the cylindrical body 1, they may be provided alternately along the circumference of the cylindrical body 1; , cuts 21..., 31..., 4... may be provided on substantially the same line along the longitudinal direction of the cylindrical body 1, respectively. The number of these cuts is preferably as large as it does not significantly affect the strength of the cylindrical body.
It is preferable to provide them as close to the lower end of the cylindrical body as possible, and it is sufficient to provide them at about three locations on the same circumference of the peripheral wall. Reference numeral 5 designates a driving head which is press-fitted into the opening at the lower end of the cylindrical body 1. The tip of the driving head 5 has a sharp shape. The anchor A is thus composed of the cylindrical body 1 and the driving head 5. Note that the lower end opening of the cylindrical body and the driving head may be screwed into male and female screws, or the driving head may be formed integrally with the cylindrical body.

As shown in FIG. 4, a plurality of anchors A having such a configuration are inserted into the embankment 8 at an acute angle to the vertical axis of the retaining wall through holes 7 drilled at predetermined intervals in the retaining wall 6.
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 6, 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.

The expansion agent 9 is applied from the upper end opening of each anchor A that has been driven in this way through the cuts 21..., 31..., 4...
Inject until it reaches the position where it is located. 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 9 hardens and expands, and reaches its maximum inflation pressure after about 12 to 24 hours. As shown in FIG. 4, this inflation pressure causes the U-shaped tongues 22..., 32
... stands up, and as the crack in the substantially linear cut 4 ... expands, the peripheral part of the cylindrical body 1 becomes enlarged (the enlarged part 10
…). Pulling resistance and supporting force are mainly applied to the anchor A by the upright U-shaped tongues 22, 32, and frictional force is applied to the anchor A by the enlarged portions 10 of the cylindrical body 1. Fig. 6 is a partial perspective view of the anchor A showing a state in which the tongue pieces 22..., 32... are erected and the cuts 4... are cracked, and Figs. 7 and 8 each omit the swelling agent. FIG. 7 is a sectional view taken along line cc and sectional view taken along line dd in FIG. 6;

The enlarged portion 10 of the cylindrical body 1 and the tongue pieces 22..., 32...
Due to the expansion of the peripheral portion of the cylindrical body 1 (the expanded portion 11 . . . ) as the anchor A rises, compressive stress is applied to the soil layer around the anchor A, resulting in consolidation. As a result, a large frictional force is generated between the anchors A... and the embankment 8, and the pull-out resistance of the anchors A... becomes extremely high.

After the expansion of the expansion agent 9 is completed, a closing fitting is attached to the upper end opening of each anchor A projecting from the retaining wall 6, and tension is applied to each anchor A using a tightening means such as a nut. By applying tension in this way, the resistance of the embankment 8 causes the tongue piece 22 to
... stands up further, and the tongue pieces 32... return slightly.
As a result, the pull-out resistance and supporting force of anchor A become larger.

As explained above, according to the construction method of the present invention,
Due to the erecting of the tongue of the anchor and the expansion of the anchor due to the expansion pressure of the expansion agent, the pull-out resistance, supporting force, and frictional force of the anchor in the ground become significantly large. Furthermore, the tongue of the anchor further stands up due to the tightening means such as a nut, and returns slightly, thereby further increasing the pull-out resistance and supporting force of the anchor. Therefore, anchors can be relatively short and small, and the number of anchors installed can be kept small. It is possible to provide good stability to retaining walls that are several meters or more than 10 meters long.
In addition, there is no need to drill a hole for anchor planting, and it is sufficient to simply drive it in, so construction can be carried out in soft ground while maintaining soil bearing capacity, and the anchor has a high pulling resistance and supporting capacity. This combination of friction and friction creates an extremely stable retaining wall.
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 construction work for retaining walls over 10 meters in height 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, FIG. 2 is a sectional view taken along line aa in FIG. 1, and FIG. 3 is a bb-b in FIG. 1.
4 is a cross-sectional view showing the anchor driven into embankment through a hole provided in the retaining wall, and FIG. 5 is a sectional view showing the tongue piece formed on the anchor due to the expansion pressure of the expansion agent. FIG. 6 is a cross-sectional view showing the anchor in the state shown in FIG. 5; FIG.
The figure is a sectional view taken along line cc in FIG. 6, and FIG. 8 is a sectional view taken along line dd in FIG. 6. 1... Cylindrical body, 21, 31, 4... Cut, 22, 3
2... tongue piece, 5... driving head, 6... retaining wall, 8... embankment, 9... swelling agent, 10, 11... ampulla.

Claims (1)

[Claims] 1. On the peripheral wall of the cylinder, make a U-shaped cut with the base facing the top of the cylinder, a U-shaped cut with the base facing the bottom of the cylinder, and a substantially straight cut, respectively. A plurality of anchors are provided, and a driving head is attached to the lower end opening of the cylindrical body, and an anchor is driven into the embankment or cut earth through a hole drilled in the retaining wall.
Next, an expansion agent is injected from the upper end opening of the anchor, and its expansion pressure causes the U-shaped tongue formed by the U-shaped cut to stand up, and expands the area around the substantially linear cut in the cylinder. Reinforcing a retaining wall by applying pull-out resistance, supporting force, and frictional force to the anchor in the ground, and then applying tension to the upper end of the anchor protruding from the retaining wall using a tightening means such as a nut. Construction method.