JPS6128046B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a method for removing existing piles, and in particular,
In addition to driving casing around the existing piles,
A liquid containing a solidifying agent is ejected inside the casing to soften the ground inside the casing, making it easier to remove the existing piles, and filling the remains of the existing piles with the softened soil to completely fill the cavity. backfill.

With urban development, new buildings are often constructed on the site of demolished existing buildings. Existing piles used in existing buildings are removed due to lack of bearing capacity or other reasons, and new piles, continuous underground walls, etc. are constructed.

Conventionally, various methods have been provided for removing existing piles, but after removing the existing piles, the cavities at the site of the existing piles are filled with granular materials such as mountain sand, sand, or cement mortar. I was putting it back. However, with this backfilling, it is difficult to backfill sufficiently and ends up leaving a cavity, which reduces the bearing strength of the ground.Furthermore, filling with concrete mortar increases the strength of the ground due to its hardening. This will result in problems with the subsequent erection of new piles and other construction work.

Therefore, the present invention was provided in order to eliminate such drawbacks of the conventional technology, and its purpose is to:
The purpose is to completely backfill the cavity where the existing pile remains, and the purpose is to facilitate ground excavation, etc. in the backfilled site, and the purpose is also to facilitate the removal of the existing pile. There is a particular thing.

That is, in this application, a cylindrical casing 2 is driven around an existing pile 1 so as to surround the existing pile 1, and a liquid containing a solidifying agent is spouted between the existing pile 1 and the casing 2. Then, the ground inside the casing 2 is softened, and then the existing piles 1 are removed, the softened ground 3 is filled into the remains of the existing piles 1, and the void near the ground surface formed above the softened ground 3 is filled with earth and sand. In addition to specifically inventing a method for removing existing piles, which is characterized by filling the existing piles with 2
A liquid containing a solidifying agent is ejected from the nozzle 5 provided inward inside the casing 2, and the casing 2 and the nozzle 5 are repeatedly moved up and down to gradually reach a certain depth inside the casing 2. After that, the existing piles 1 are removed, the softened ground 3 is filled into the remains of the existing piles 1, and the void near the ground surface formed above the softened ground 3 is filled with earth and sand 4, etc. A method for removing existing piles characterized by the following is defined as a combined invention.

Next, these inventions will be explained in detail based on the accompanying drawings.

FIG. 1 shows the existing pile 1 still in place, and a cylindrical casing 2 is driven around the existing pile 1 so as to surround it. FIG. 2 shows a state in which the casing 2 is being driven in. An injection pipe 6 is fixed to the inside of the casing 2, and a liquid containing a solidifying agent is spouted from the nozzle 5 toward the existing pile 1. The casing 2 is given vibration and is gradually driven downward, but the casing 2 gradually descends while repeatedly moving up and down as appropriate. Of course, the casing 2 and the injection pipe 6 move simultaneously.

Then, the liquid spouted from the nors 5 softens the ground. As a result, the friction between the existing pile 1 and the ground is significantly reduced. The liquid sufficiently penetrates between the soil particles that form the ground due to the jetting, and the soil and the liquid are sufficiently mixed by the jetting pressure, resulting in fluidity in the softened ground.

The number of injection pipes 6 and nols 5 is appropriately determined depending on the dimensions of the existing piles 1, the properties of the ground, etc. Also,
In the illustrated example, the injection pipe 6 is fixed to the casing 2, but these may have independent structures. In this case, the movements of both do not necessarily have to be synchronized as described above. However, if the injection pipe 6 is fixed in the casing 1 as described above, there is an advantage that the injection pipe 6 can also be plunged into the ground at the same time by driving only the casing 1.

FIG. 3 shows a state in which the ground has softened to the lower end of the existing pile 1. Therefore, the existing pile 1 is removed.
This removal is because the ground around the existing pile 1 has already softened and the friction has decreased.
It can be done very easily.

After removing the existing pile 1, only the softened ground 3 remains inside the casing 2. Since the softened ground 3 has fluidity as described above, the surrounding softened ground 3 flows in and fills the cavity where the existing pile 1 was located as soon as the existing pile 1 was removed. At this time, the softened ground 3 flows into the cavity because the pressure at the site of the existing pile 1 decreases as the existing pile 1 is removed.
The softened ground 3 flows as if being sucked into the low pressure area. Thus, the change in pressure and the softening of the ground 3
Due to its own weight, the cavity is smoothly filled. This is not something that is filled once the cavity is formed, but is actually filled before the cavity is formed.
It will be filled when the existing piles are removed.

Therefore, unlike filling a cavity once formed, no cavity remains.

When the existing pile 1 is removed, a void with a volume corresponding to the volume of the existing pile 1 is formed near the ground surface. Therefore, this void is filled with earth and sand 4, etc., as shown in FIG. At this time, filling with the earth and sand 4 is completed by simply using a handy vibrator. This is because the depth is small.

Cement and the like can be considered as the solidifying agent used in this method. Cement is mixed with the softened ground and used to solidify the ground to a low strength level. In addition, if the volume of the existing pile 1 is large, in order to prevent the softened ground 3 from becoming insufficient due to its removal, dihydrate gypsum, bentonite mortar, etc. are used as a bulking material.

The filling of the earth and sand 4 can be done before or after the removal of the casing 2, but it is preferable to fill it before the removal of the casing 2 because this can prevent the ground from collapsing near the ground surface.

Note that it is preferable that the compressive strength of the ground backfilled by this method is about 1 to 3 kg/cm ² for the next excavation, etc.

As is clear from the above, according to this invention,
As the existing piles are removed, the internal pressure that occurs due to the removal decreases and the weight of the softened ground makes it possible to completely backfill the cavity where the existing piles remained, and to maintain the strength of the ground after the backfilling. Therefore, work such as ground excavation can be facilitated. Furthermore, according to the present invention, the friction on the existing pile can be reduced without adding any additional steps, and therefore the removal of the existing pile can be made extremely easy.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a sectional view showing an existing state of an existing pile;
Figure 2 is a cross-sectional view of the state in which the casing is driven and the ground is softened, Figure 3 is a cross-sectional view of the state where the casing has been driven and the ground softened, and Figure 4 is the upper part after the existing pile has been removed. FIG. 5 is an enlarged cross-sectional view taken along the line 5-5 in FIG. 3. In addition, in the figure, 1 is the existing pile, 2 is the casing,
3 is softened ground, 4 is earth and sand, and 5 is nors.

Claims (1)

[Scope of Claims] 1. A cylindrical casing is driven around the existing pile so as to surround the existing pile, and a liquid containing a solidifying agent is spouted between the existing pile and the casing, so that the inside of the casing is After that, the existing piles are removed and the softened ground is filled into the existing pile remains.
Furthermore, the method for removing existing piles is characterized by filling a void near the ground surface formed above the softened ground with earth and sand. 2. While driving a cylindrical casing around the existing pile so as to surround the existing pile, a liquid containing a solidifying agent is injected between the existing pile and the casing from a nozzle installed inside the casing facing inward. The ground inside the casing is gradually softened to a certain depth by repeatedly moving the casing and the nors up and down as appropriate.
Thereafter, the existing pile is removed, the existing pile remains are filled with softened ground, and the void near the ground surface formed above the softened ground is filled with earth and sand.