JP2749388B2 - Retaining method for soft ground - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of fixing a soft ground by anchoring an anchor to the soft ground.

[Conventional technology]

When constructing an underground structure, a retaining wall is constructed as a retaining ground for the surrounding ground, thereby preventing the collapse of the surrounding ground. As this retaining wall, it is known to use a wall such as a mixed solidified wall at the current position, a continuous wall of concrete, a parent pile horizontal sheet pile, or the like, if the strength of the surrounding ground is sufficient, the construction of an underground structure is required. When excavating the enclosed area, the wall is supported by an anchor planted on the ground to prevent deformation of the retaining wall due to earth pressure or water pressure. The support of the retaining wall by the anchor is excellent in the workability of constructing the underground structure because there are no obstacles or the like in the construction area of the underground structure surrounded by the retaining wall.

On the other hand, if the surrounding ground is soft, it is not possible to expect anchoring power of the ground, so in the construction area of the underground structure surrounded by the retaining wall, the beam is cut between the opposed retaining walls. To support the retaining wall with this cutting beam.

[Problems to be solved by the invention]

However, in the case where the surrounding ground is soft, since a cutting beam for supporting the retaining wall is hung in the construction area of the underground structure, this is a hindrance to the construction work of the underground structure. There was a problem that it was not good.

Therefore, the present invention has been made to support the retaining wall with an anchor even when the ground around the construction area for the underground structure is soft.

[Means for solving the problem]

The method of retaining the soft ground according to the present invention includes:
A fixing area is formed by solidifying the ground, a mountain retaining wall is disposed on the soft ground, and an anchor supporting the mountain retaining wall is anchored in the fixing area.

The fixing zone is formed by widening and rotating the wings in the ground while injecting the solidifying agent by using a deep mixer having a wing that can be widened and a supply port of a solidifying agent around the wings, and injecting the solidifying agent into the soft soil. After the agitation with the solidifying agent, the agitation zone can be solidified. It is also possible to use a conventional deep-layer mixer or a jet-stirring mixer.

The fixing area may be formed in a plurality in the depth direction of the ground, and each fixing area may be individually formed in a block shape, or may be formed continuously in the depth direction to form a wall shape.

[Action]

Since a part of the soft ground is solidified to form an anchoring area for the anchor, the anchoring force of the anchor increases, and the passive earth pressure generated in front of the anchoring area is used, so that the anchoring area can be increased. The supporting force of all the retaining walls can be made sufficient, and the supporting of the retaining walls by the cutting beams can be eliminated or the number of the cutting beams can be reduced.

When the fixing area is formed by a deep mixer or the like, the work of solidifying the ground is simplified, and this work is performed a plurality of times in the depth direction of the ground to form a plurality of the fixing areas in the depth direction of the ground. can do. Thus, since each fixing area is individually formed in a block shape, it is easy to destroy or remove the fixing area when using the surrounding ground.

〔Example〕

1 to 3 are views showing an embodiment, and will be described first with reference to FIGS.

Reference numeral 1 denotes a construction area for constructing an underground structure such as a basement floor of a building, which is formed by excavating the ground, and reference numeral 2 denotes a soft ground around the ground. Prior to the excavation of the construction area 1, first, a predetermined position of the ground 2 is solidified in the soft ground 2 to form a fixing area 3.
The solidification process is performed by mixing a solidifying agent such as cement milk into the earth and sand forming the soft ground 2 and stirring and solidifying the mixture. The solidified portion is the fixing area 3.

In this state, the construction area 1 is excavated and gradually excavated, and the excavation places the retaining wall 4 on the end face of the soft ground 2. Next, an anchor hole 5 extending from the retaining wall 4 to the fixing area 3 through the soft ground 2 is formed, and a known anchor 6 is inserted into the anchor hole 5 so that the tip of the anchor 6 is fixed to the fixing area 3. Edge retaining wall 4 using horizontal flap 7 etc.
Fixed to The formation of the anchor holes 5 and the insertion of the anchors 6 are performed by conventional means.

The embedding of the retaining wall 4, the formation of the anchor hole 5, and the insertion and fixing of the anchor 6 are repeatedly performed sequentially downward as the excavation of the construction area 1 progresses, but in a range where there is no danger of the soft ground 2 collapsing. In the above, after excavating the construction area 1 to a certain depth at a stretch, it is also possible to construct the retaining wall 4, form the anchor hole 5, and insert and fix the anchor 6 at a time in a plurality of steps. These procedures are also performed as usual.

Incidentally, a plurality of fixing areas 3 are formed in the depth direction of the soft ground 2, and each fixing area 3 is formed in a block shape.

A method for forming the fixing area 3 will be described with reference to FIG. The formation of the fixing zone 3 is performed by using a deep-layer mixer 8, which comprises a wide-width wing 11 attached to the lower end of a rotating shaft 10 that can move up and down along a vertical boom 9. It has a supply port (not shown) of the solidifying agent around the wing 11 and a water supply port (not shown) for making it liquid at a predetermined position on the soft ground 2, and is constructed in the following procedure. .

First, as shown in FIG. 3 (a), a hole is drilled while pouring water to a predetermined depth of the soft ground 2, and then, as shown in FIG. Wing 11
open. Further, as shown in FIG. 3 (c), widening and drilling are performed while continuing water injection even after the completion of the blade opening, and then a solidifying agent such as cement milk is added while rotating the blades as shown in FIG. 4 (d). Inject, mix with the earth and sand at the current position, and further raise and lower the blades 11 together with the rotating shaft 10 to perform sufficient stirring. At the end, the wing is closed and pulled up as shown in FIG.

3 (a) to 3 (e) are for forming one fixing area 3, but the above-mentioned steps are performed on the soft ground 2
By repeatedly performing the fixing at a plurality of inner depths, a plurality of fixing areas 3 as shown in FIGS. 1 and 2 can be formed. In this case, it is preferable to perform the fixing from the lowermost fixing area 3 and to sequentially form the fixing area 3 thereabove.

Thus, the fixing area 3 is formed on the soft ground 2,
Since the anchor 6 is fixed to this, the anchoring force of the anchor 6 becomes large similarly when the anchor 6 is fixed on the ground having sufficient strength. For this reason, it is not necessary to hang a cutting beam between the retaining walls 4 arranged on both sides of the construction area 1 so as to support the retaining walls 4 and to oppose the earth pressure or the water pressure. Even if needed, the number is small enough. Therefore, since the space of the construction area 1 can be widely secured, construction workability of the underground structure is good.

Also, the condition of the soft ground 2 is the fixing area 3 shown in FIGS.
In this case, when it is expected that the strength is not sufficient for anchoring the anchor 6, the reinforcing member 12 may be built in the central continuous portion 3a of the anchoring area 3 which is vertically continuous. As the reinforcing member 12, a steel material such as an H-section steel or the like is appropriate, and it is particularly preferable that the reinforcing member 12 be built before the fixing region 3 is solidified. In this case, by applying a release agent, a sliding film, or the like to the outer periphery of the reinforcing member 12, it is easy to remove the underground structure after the completion of the underground structure in the construction area 1. When it is necessary to remove or crush the fixing area 3 after the removal, the fixing area 3 is easy to remove and crush easily because a plurality of the fixing areas 3 are blocked. Therefore, there is an effect that no obstacle remains when the soft ground 2 is reused.

Although the retaining wall 4 in the above embodiment is shown integrally over the upper and lower sides, it is possible to add a plurality of materials in a multi-tiered configuration, because the material can be added downward as the excavation depth of the construction area 1 increases. It is suitable. Further, in the above-described embodiment, the horizontal butter 7 is used, but other members may be used as long as the anchor 6 can be fixed, or the anchor 6 may be directly fixed to the retaining wall 4 without using these members.

〔The invention's effect〕

As described above, according to the present invention, the anchoring force of the anchor increases because a part of the soft ground is solidified and the anchoring area of the anchor is formed. Thus, the supporting force of the retaining wall can be sufficient. For this reason, it is not necessary to support the retaining wall by the girder or the number of the girder can be reduced, so that the space in the construction area of the underground structure excavated at the front of the girder wall is widened and workability is improved. .

Further, when the fixing area is formed by a deep mixer,
The work of solidifying the ground is simplified and the working efficiency is increased.

Further, by forming the fixing area a plurality of times in the depth direction of the ground, a plurality of the fixing areas can be formed in the depth direction of the ground. Thus, since each fixing area is individually formed in a block shape, when the surrounding ground is used later, there is an effect that the fixing area can be easily broken or taken out.

[Brief description of the drawings]

1 to 3 show an embodiment. FIG. 1 is a sectional view showing a state in which an anchor hole is formed in a soft ground and a fixing area formed in the soft ground, and FIG. 2 shows a state where an anchor is fixed. 3 (a) to 3 (e) are sectional views showing the order of forming the fixing areas. 1 ... construction area, 2 ... soft ground, 3 ... fixing area, 4 ...
... Mounting wall, 5 ... Anchor hole, 6 ... Anchor, 8 ...
… Deep mixer, 9… Boom, 10… Rotary axis, 11… Wings

Claims (3)

(57) [Claims] 1. A method of solidifying a ground in a soft ground to form a fixing area, arranging a retaining wall on the soft ground, and fixing an anchor supporting the retaining wall to the fixing area. The method of retaining the soft ground characterized by the following characteristics. 2. A deep mixing machine having a wing that can be widened and a supply port of a solidifying agent around the wing, the wing is widened and rotated in the ground, and a solidifying agent is injected to solidify the soft soil at the site. 2. The method of claim 1, wherein the stirring area is solidified to form a fixing area after the agent is stirred. 3. The method according to claim 1, wherein a plurality of fixing areas are formed in the depth direction of the ground, and each fixing area is formed in a wall shape. .