JPH0242968B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a treatment method for pulling out piles buried underground.

(Prior Art) Piles buried underground, for example, piles used for constructing earth retaining walls, are pulled out and removed after construction of the underground structure is completed.

By the way, in order to pull out a pile, large-scale extraction equipment that can exert a pulling force on the pile that exceeds the pile's own weight and the frictional force between the pile and the surrounding ground is required, and the scale of the extraction equipment is based on the length of the pile. There was a problem in that it had to be made larger as the size increased.

One possible way to solve this problem is to apply a hydrous gel, which has the property of liquefying like grease over time in an alkaline atmosphere, to the surface of the pile when burying the pile. It is thought that when a pile is pulled out, if a grease-like substance is present between the buried pile and the ground, the frictional resistance when pulling out the pile can be reduced.

The hydrogel can be formed by leaving a mixture of a water-soluble urethane prepolymer and water for a predetermined period of time, and when the mixture is applied to the surface of the pile, the mixture solidifies or gels over time. and becomes a hydrogel. The mixture can be applied to the surface of the pile by spraying the mixture onto the surface of the pile. However, as described above, since this mixture has the property of gelling over time, it is difficult to apply the mixture to the surface of the pile. As the gelation progresses during the spraying of the mixture, the mixture is stored in a storage tank, in a feeding facility for sending the mixture from the storage tank to a nozzle, and in a nozzle for jetting the mixture. A solidified substance (hydrous gel) is formed at the tip, which not only makes it impossible to spray, but also makes it extremely difficult to wash off the attached hydrogel with various solvents, making it virtually impossible to reuse these equipment. The problem is that it becomes impossible. To address this problem, it is possible to use a mixture with a relatively long gel time. However, this only prolongs the time until the water-containing gel is produced, thereby extending the time until the spraying becomes impossible, and it becomes impossible to reuse the equipment. It cannot be avoided.

(Object of the Invention) Therefore, the present invention significantly reduces the pull-out resistance of a pile by forming a hydrous gel on the surface of the pile that has the property of changing into a grease-like state over time in an alkaline atmosphere. At the same time, it is possible to eliminate factors that make it impossible to spray the substance to be sprayed onto the surface of the pile for the formation of the hydrous gel and make it impossible to reuse the equipment used for the spraying. The object of the present invention is to provide a processing method for pulling out piles.

(Structure of the Invention) The present invention involves separately and simultaneously spraying a water-soluble urethane prepolymer and water to form a hydrogel coating on at least a portion of the surface of a pile, and placing the pile in an alkaline atmosphere. It is characterized by being buried inside.

(Operations and Effects of the Invention) According to the present invention, the hydrous gel coating formed on the surface of the pile reacts with an alkaline substance and turns into a grease-like coating over time, and the pile and the ground are coated with the grease. It is reliably separated by a substance that exhibits a shape. The grease-like substance is
When pulling out piles, it acts as a lubricant between the pile and the ground, so the force required to pull out the piles can be significantly reduced, making it possible to downsize the equipment required to pull out the piles. .

Further, according to the present invention, a water-soluble urethane prepolymer and water are separately and simultaneously sprayed onto the surface of the pile, thereby coating the sprayed surface with a mixture thereof to form a hydrogel coating.

The water-soluble urethane prepolymer, which has the property of gelling in the presence of water, is fed separately from the water and sprayed, so the water-soluble urethane prepolymer, which is the equipment used for spraying, Polymer storage containers, their feeding equipment,
This does not solidify at any point such as the nozzle that sprays it to the outside, so water-soluble urethane prepolymer and water are continuously sprayed over a long period of time to form a hydrous gel film. can be done. The invention also allows the use of mixtures in which, for example, a catalyst is added, thereby shortening the gel time. A mixture with a short gel time solidifies in a relatively short period of time after being sprayed onto the pile surface, which reduces the amount of dripping and can form a hydrogel coating with a uniform thickness over the entire surface. It is advantageous.

(Embodiments) The features of the present invention will become clearer from the following description of the illustrated embodiments.

As an example, a treatment method applied when constructing an earth retaining wall will be explained.

First, before inserting the pile into a trench drilled in the ground, a mixture of water-soluble urethane prepolymer and water is applied to at least a portion of the surface of the pile, and this is left for a predetermined period of time (gel time). This forms a hydrogel film. The hydrogel has a property of being weak against alkali. Application of the mixture is carried out by spraying the water-soluble urethane prepolymer and water separately and simultaneously onto the surface of the pile. This spraying can be performed using a device described below.

The water-soluble urethane prepolymer is obtained by urethane bonding a hydrophilic polyoxyalkylene polyol and an organic polyisocyanate to leave an isocyanate group at the end. The polyoxyalkylene polyols include condensates and co-condensates of ethylene glycol, propylene glycol, glycerin, and the like.

The pile on which the hydrogel coating is formed is made of steel,
It may be made of concrete or wood, and may have any shape such as a tube, a box, an I-shape, an H-shape, or a plate like a sheet pile.

Typical examples of constructing the earth retaining wall 10 by forming grooves in the ground include the so-called mud solidification method shown in Figures 1 to 5, and the so-called soil cement column pile method shown in Figures 6 to 8. There is a so-called joist construction method shown in FIGS. 9 to 12.

In the muddy water solidification method, a trench 12 is excavated while being filled with a stable liquid such as bentonite mud (Fig. 3), and then a pile 14 is inserted into the trench 12 (Fig. 4). A solidifying agent such as cement is poured into the groove 12 to solidify the stabilizing liquid, thereby constructing the earth retaining wall 10.

In the soil-cement column pile construction method, a trench hole 12 is bored to a predetermined depth using an excavator such as an earth auger, and then a solidifying material such as cement paste or mortar is injected into the trench hole 12. The earth and sand remaining in the trench 12 are stirred and mixed (Fig. 7). Next, the stake 14 is inserted into the slot 12 (FIG. 8). Thereafter, the area around the pile 14 is solidified to form the earth retaining wall 10.

In addition, in the joist construction method, after forming the groove hole 12 by pre-boring (Fig. 10), the pile 14 is inserted into the groove hole (Fig. 11).
The earth retaining wall 10 is constructed by backfilling with earth and sand.

In order to form the water-containing gel coating on the surface of the pile 14, the water-soluble urethane prepolymer and water are added at the temporary pile pile site or when the pile is placed above the trench, that is, when the pile is erected. This is done by spraying. In order to increase the efficiency of forming the hydrous gel coating and reduce the chance of damage to the coating after formation, it is desirable to spray the water immediately before inserting the pile 14 into the trench, that is, when the pile is erected.

In this case, as shown in FIGS. 13 to 15, by using a spraying device 16 installed on the ground surface above the trench 12, the water-containing gel is applied to the surface of a pile 14 such as an H-shaped steel. can be formed.

This device 16 includes a frame 18 that surrounds the open end of the slot 12 and is placed on the ground surface, a cylindrical cover 20 that is fixed on the frame, and a side surface of the cover that is inserted from the outside. A plurality of tubes 22 are provided extending through the tubes 22 and spaced apart from each other by 90 degrees.

The tube 22 is made of a double tube, and a nozzle for spouting out the water-soluble urethane prepolymer and water is formed at the tips of an outer tube 22a and an inner tube 22b that opens inside the outer tube, respectively. The polyurethane prepolymer and water are simultaneously ejected from each nozzle and mixed just before the nozzle of the outer tube 22a.

While the pile 14 made of H-shaped steel moves down inside the slot 12 through the cover 20 and the frame 18, the outer pipe 22
The mixture of the water-soluble urethane prepolymer and water is sprayed from the nozzle a and applied to the surface of the pile 14.

In the illustrated example in which the pipe 22 is a double pipe, the water-soluble urethane prepolymer is separated from the water with which it is mixed, such as in its storage container, feeding equipment to the nozzle (not shown), etc. Because of this, it does not solidify in these equipment during spraying. However, the water-soluble urethane prepolymer and water pass through the nozzle at the tip of the outer tube 22a. Therefore, a portion of the mixture adheres to the nozzle and solidifies. However, the amount is relatively small because the exit velocity and exit pressure of the mixture during passage through the nozzle are relatively high. Therefore, the mixture can be sufficiently applied to the pile surface using the device 16, but in order to completely eliminate adhesion and solidification of the mixture at the nozzle, it is necessary to apply the water-soluble urethane prepolymer to the pile surface. The jetting tube and the water jetting tube can be two independent tubes (not shown). In this case, the water-soluble urethane prepolymer and the water are mixed and sprayed onto the surface of the pile 14 while simultaneously spouting the water-soluble urethane prepolymer and the water from nozzles provided in each tube.

The pile 14 is inserted into the slot 12 after the mixture has gelled at the point of application. Until the area where the mixture is applied to the pile 14 gels,
Although the pile 14 is stopped at a fixed height position, this stopping time can be shortened by shortening the gel time.

The gel time can be achieved by increasing the temperature of the water (30°C to 50°C), increasing the mixing ratio of the water-soluble urethane prepolymer within a range that does not exceed the amount of water, or adding a higher amine such as triethylene diamine. , can be shortened by adding a catalyst such as an organotin compound such as dibutyltin dilaurate.

The mixture 15 of the water-soluble urethane prepolymer and water is applied to the entire surface of the pile 14 (the first
(Fig. 6), the surface of the lower part of the pile 14 (Fig. 17), the surface of the parts of the pile 14 at several levels in the longitudinal direction (Fig. 18), the surface of the lower part of the pile 14 and the surface from the lower part upwardly. There are surfaces of parts at multiple levels (Figure 19), etc., which are determined by taking into account the target ground, the applied construction method, etc.

After the mixture 15 is applied to the surface of the pile 14 and gelled as described above, the pile 14 is inserted into the slot 12, and the slot 12 is then filled with a material having alkaline properties. Insertion of the pile 14 into the slot 12 is as follows:
This may be done after the grooves 12 are filled with an alkaline substance, as in the soil cement column pile construction method.

At this time, when using the muddy water solidification method and the soil cement column pile method, the groove hole 1 is
2 is filled.

When using the joist construction method, if the ground is alkaline, the excavated soil may be backfilled as is, or if the ground is non-alkaline, an alkaline material such as cement or lime may be used in the backfilling. Mix something with ingredients. Furthermore, when the soil is not non-alkaline but is in a similar state, it is preferable to mix cement or lime into the backfill soil.

By filling the slot 12 with the material containing an alkaline component, the hydrogel formed on the surface of the pile 14 reacts with the alkaline component, and the hydrogel coating gradually softens, forming a grease-like coating. Changes to It takes about a few days for the hydrogel coating to become partially greasy, but since piles are generally pulled out at the earliest several months after they are buried, Almost all of the hydrogel coating turns into a grease-like coating. As a result, when the pile is pulled out, the pile and the surrounding solidified layer or backfill earth and sand are almost completely separated, and when the pile is pulled out, the coating that changes into a grease-like form acts as a lubricant, reducing the pulling resistance. .

It is possible to bury the pile in the ground by driving the pile instead of using a method of burying the pile in the ground by providing a groove in the ground in advance and inserting the pile into the groove. In this case, when the ground has alkaline soil quality, the pile is buried in the ground after forming a coating of the hydrous gel on its surface in the same manner as when inserting the pile into the groove.

The hydrous gel on the surface of the pile reacts with alkaline components in the ground surrounding the pile, softens it, and eventually becomes grease-like.

In addition, whether the pile is buried in the ground by drilling a trench in advance or by driving the pile into the ground, the above-mentioned water content on the surface of the pile that constitutes the root cut surface Gel formation can be omitted.

[Brief explanation of the drawing]

Figures 1 and 2 are schematic cross-sectional views of an earth retaining wall constructed according to the mud solidification method, and Figures 3 and 4 are
Figure 5 and Figure 5 are schematic diagrams showing the steps of the mud water solidification method, Figure 6 is a schematic cross-sectional view of an earth retaining wall constructed according to the soil cement column pile method, and Figures 7 and 8 are soil A schematic diagram showing the steps of the cement column pile construction method, Figure 9 is a schematic cross-sectional view of an earth retaining wall constructed according to the joist construction method, Figure 10,
Figures 1 and 12 are schematic diagrams showing the process of the Jyoist method, Figure 13 is a front view of the water-soluble urethane prepolymer and water spraying equipment, Figure 14 is a plan view of the spraying equipment, and Figure 15 is a double The partially enlarged cross-sectional view of the pipe, FIGS. 16, 17, 18, and 19 are vertical cross-sectional views of the pile showing locations where hydrogel is formed. 12: Slot, 14: Pile, 15: Mixture of water-soluble urethane prepolymer and water, 16: Spraying device.

Claims (1)

[Scope of Claims] 1. Spraying a water-soluble urethane prepolymer and water separately and simultaneously to form a hydrogel coating on at least a portion of the surface of the pile, and inserting the pile into a groove hole; A method for the extraction of piles, the method comprising: thereafter filling the slot with a material having alkaline properties. 2. Spraying a water-soluble urethane prepolymer and water separately and simultaneously to form a hydrogel coating on at least a portion of the surface of the pile, filling the slot with an alkaline material, and then A method for extracting a pile, comprising inserting the pile into the slot. 3. A pile comprising separately and simultaneously spraying a water-soluble urethane prepolymer and water to form a hydrous gel coating on at least a portion of the surface of the pile, and then burying the pile in the ground of alkaline soil. Processing method for extraction.