JPS6339730B2 - - Google Patents

Description

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

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 form a hydrous gel on the surface of the pile, which has the property of liquefying into a grease-like form over time in an alkaline atmosphere, when the pile is buried. 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.

However, with this method, the ground in which the piles with the hydrous gel formed are to be buried is limited to cases where the ground has alkaline soil. There are two ways to bury piles: by inserting the pile into a trench drilled in the ground in advance, and by driving the pile into the ground. If the soil quality of the ground is non-alkaline, it is sufficient to mix an alkaline substance into the filling material used to fill the trench, but in the latter case, where piles are driven, this method of handling is not recommended. Can not. In addition, the more alkaline the alkaline substance that reacts with the hydrous gel, the more likely it is to turn into a grease-like substance. The strength may not be sufficient to transform the hydrogel.

Therefore, the present invention has been developed by forming a water-containing gel on the surface of the pile, which has the property of changing into a grease-like state over time by reacting with an alkaline substance, and by forming a water-containing gel on the surface of the pile. To provide a processing method for pulling out piles that can significantly reduce the pulling resistance of piles regardless of whether they have soil quality.

In the treatment method according to the present invention, after forming a coating consisting of a layer of an alkaline substance and a layer of hydrogel obtained by reacting a water-soluble urethane prepolymer with water on at least a part of the surface of the pile, is inserted into the slot, and then the slot is filled.

Further, the present invention is characterized in that the pile on which the coating is formed is buried directly in the ground, for example, by driving, instead of in the groove.

According to the present invention, the hydrogel layer may be formed on the outside or inside of the alkaline substance, and in either case, the surrounding ground surrounding the pile has alkaline soil. Regardless of the presence or absence of the substance or its strength, the water-containing gel reacts with the alkaline substance and turns into a grease-like substance over time. separated. The grease-like substance acts as a lubricant between the pile and the ground when the pile is pulled out, which can significantly reduce the force required to pull out the pile. It is possible to downsize.

In the present invention, after forming a coating consisting of a layer of an alkaline substance and a layer of a water-soluble urethane prepolymer on at least a portion of the surface of the pile, the pile is inserted into a trench containing groundwater or a stabilizing liquid. , and then filling the slot.

In addition, the present invention provides a method in which the pile on which the coating consisting of the layer of the alkaline substance and the water-soluble urethane prepolymer layer is formed is not placed in a trench, but is driven, for example, so that the location where the coating is formed is located below the groundwater level. It is characterized by being buried directly in the ground.

According to the present invention, when the layer of the water-soluble urethane prepolymer comes into contact with the stabilizing liquid or ground water, it reacts with the water and changes into a hydrogel.
The hydrogel reacts with the layer of the alkaline substance. Therefore, regardless of whether or not the surrounding ground surrounding the pile has alkaline soil or its strength, the water-containing gel reacts with the alkaline material forming the layer, and over time, the pile and It turns into a grease-like substance that reduces the friction between the surrounding ground.

(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 excavated in the ground, at least a portion of the surface of the pile is coated with a layer of an alkaline substance (hereinafter simply referred to as "alkaline substance") and a water-soluble urethane prepolymer. A film consisting of a layer of hydrogel obtained by reacting with water is formed. This hydrogel has a property of being weak against alkali.

The coating is made by coating the surface of the pile at a predetermined location with the alkaline substance, and then coating the alkaline substance layer with the hydrogel layer, or forming the hydrogel layer on the surface of the pile. Thereafter, the hydrogel layer can be formed by covering it with a layer of the alkaline substance.

The alkaline substance may be composed of, for example, a mixture of water glass and cement paste, and the layer of the alkaline substance may be formed by applying the mixture to the surface of a predetermined portion of the pile in a layered manner, or , it can be formed by applying the kneaded material to cover the layer of the hydrogel. Further, the alkaline material layer can also be formed by spraying a powdery alkaline material.

The hydrogel can be formed by spraying the water-soluble urethane prepolymer and water separately and simultaneously onto the layer of alkaline material or the surface of the pile at a predetermined location. 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.

By the way, the earth retaining wall 10 is constructed by forming a groove in the ground.
Typical examples of construction are the so-called mud solidification method shown in Figures 1 to 5, and the
There are the so-called soil-cement column pile method shown in the figure, and the so-called joist 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 hydrous gel layer on the surface of the pile 14 or on the surface of the layer of alkaline material applied to the surface, it is possible to form the layer of hydrogel on the surface of the pile 14 or on the surface of the layer of alkaline material applied to the surface. This can be done at the time of construction. 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. It can be formed on the layer of the alkaline material to be coated or on the surface of the pile 14.

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 water-soluble urethane prepolymer and water injected from the nozzle a is sprayed onto the layer of alkaline material or the surface of the pile 14, and gels over time.

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, although the application of the mixture to the layer of alkaline material or the surface of the pile can be sufficiently performed using the device 16, in order to completely eliminate adhesion and solidification of the mixture at the nozzle, The pipe for ejecting the water-soluble urethane prepolymer and the pipe for ejecting the water can be two independent pipes (not shown). In this case, the water-soluble urethane prepolymer and the water are simultaneously jetted from nozzles provided in each tube, and the two substances are mixed and sprayed onto the layer of the alkaline material or the surface of the pile 14.

The piles 14 are inserted into the slots 12 after the formation of the alkaline substance layer when the hydrogel layer is covered with the alkaline substance layer, and after the formation of the alkaline substance layer when the hydrogel layer is coated with the alkaline substance layer. In the case of coating, this is done after the mixture has gelatinized into a water-containing gel at the application site. Until the area where the mixture is applied to the pile 14 gels, the pile 14 is stopped at a certain height, but 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 coating formed of the alkaline substance layer and hydrogel is formed on the entire surface of the pile 14 (16th
Figure), surface of the lower part of pile 14 (Figure 17), pile 1
The surface of the portion at multiple levels in the longitudinal direction of the pile 14 (Figure 18), the surface of the lower portion of the pile 14, and the surface of the portion at multiple levels above the lower portion (Figure 19), etc. , determined in consideration of the applicable construction method, etc.

After the coating is formed as described above, the pile 14
into the slot 12 and then fill the slot 12. The piles 14 may be inserted into the slots 12 after the slots 12 have been filled, as in the soil-cement column pile 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 and the pile 14 is buried.

In the case of the joist construction method, the trench is filled by backfilling the excavated earth and sand as it is, and the pile 14 is buried.

When the layer of alkaline material is made of a kneaded mixture of water glass and cement paste, from the time when the hydrogel is formed on the layer of alkaline material, the layer of alkaline material is When the alkaline substance absorbs moisture in the ground surrounding the pile due to the burial of the pile,
The alkaline substance and the hydrogel react, and the hydrogel layer gradually softens and becomes grease-like. It takes approximately several days for the hydrous gel layer 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 layer turns into a grease-like layer. 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. .

The alkaline component that reacts with the hydrogel layer is
Since it is a layer of the alkaline substance that forms a coating together with the hydrous gel, the backfill soil in the Jyoist construction method is of non-alkaline soil and the layer of hydrous gel is formed by the action of the ground around the pile. Even if the layer of hydrogel cannot be expected to change into a grease-like state, the hydrogel layer can be reliably changed into a grease-like state. Further, when the surrounding ground has an alkaline filling material as in the mud solidification method or the soil cement column pile method, and the layer of hydrous gel covers the layer of alkaline material, , the hydrogel reacts with both the alkaline substance and the alkaline component in the filler material.

In the example described above, the pile 14 was inserted into the slot 12 after forming a layer of hydrous gel constituting a coating together with the layer of the alkaline substance on the surface of the pile 14 . However, if underground water, a stabilizing liquid, or a solidifying material containing moisture such as mortar or cement paste is present in the excavated trench 12, this is used instead of the water-containing gel layer. By inserting this layer into a slot, water in the slot can react with the water-soluble urethane prepolymer to form a layer of hydrogel.

In this case, it is desirable to mix a fine particulate material such as fly ash, clay, or bentonite into the water-soluble urethane prepolymer prior to coating it. This makes it possible to increase the amount of coating material and to prevent dripping when only the water-soluble urethane prepolymer is coated. Further, the mixture of the water-soluble urethane prepolymer and the fine particulate material can be applied by roller coating or brush painting, and the presence of the fine particulate material improves the coating performance at this time. Furthermore, since the water-soluble urethane prepolymer is applied to the surface of the pile while surrounding the fine particles,
The coated surface exhibits an uneven shape, and the surface area of the coated surface can be substantially increased compared to when the water-soluble urethane prepolymer is applied alone, thereby accelerating gelation of the water-soluble urethane prepolymer. be able to.

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, regardless of whether the ground has alkaline soil quality or not, the layer of the hydrogel or the water-soluble urethane prepolymer is applied to the surface of the pile in the same manner as when inserting the pile into the groove. After forming the coating having the layer of alkaline material, it is buried underground by driving a pile.

When driving into the ground a pile coated with a water-soluble urethane prepolymer or a mixture of the same and the fine particulate material instead of the hydrogel, the application site should be located below the groundwater level. As a result, the water-soluble urethane prepolymer reacts with groundwater to form a hydrogel layer similar to that described above on the surface of the pile.

As described above, the hydrous gel layer on the surface of the pile is softened by reacting with the alkaline substance or with the alkaline substance and the alkaline components in the ground surrounding the pile. Becomes greasy.

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 Figure 9 is a schematic diagram showing the steps of the cement column pile construction method;
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 sectional view of the pipe, and FIGS. 16, 17, 18, and 19 are vertical sectional views of the pile showing the locations where the coating is formed. 12...Slot, 14...Pile, 15...Mixture of water-soluble urethane prepolymer and water, 16...
Spraying equipment.

Claims (1)

[Scope of Claims] 1. Forming on at least a portion of the surface of the pile a coating consisting of a layer of an alkaline substance and a layer of hydrogel obtained by reacting a water-soluble urethane prepolymer with water; A method for the extraction of piles, the method comprising: inserting a pile into a slot, and subsequently filling said slot. 2. The treatment method according to claim 1, wherein the alkaline substance is a mixture of water glass and cement paste. 3. The treatment method according to claim 1, wherein after applying the alkaline substance to the surface of the pile, the alkali substance is coated with the hydrous gel. 4 After applying the hydrogel to the surface of the pile,
The treatment method according to claim 1, wherein the hydrogel is coated with the alkaline substance. 5. The treatment method according to claim 1, wherein the water-containing gel layer is formed by spraying the water-soluble urethane prepolymer and the water separately and simultaneously onto the surface of the pile and mixing them to react. 6. Forming a coating consisting of a layer of an alkaline substance and a layer of a water-soluble urethane prepolymer on at least part of the surface of the pile, inserting the pile into a trench containing groundwater or a stabilizing liquid, and then A processing method for the extraction of piles, comprising filling said slots. 7 Applying an alkaline substance to at least a portion of the surface of the pile, coating the alkaline substance with a hydrous gel obtained by reacting a water-soluble urethane prepolymer with water, and then placing the pile in the ground. Processing methods for the extraction of piles, including burying them inside. 8. The treatment method according to claim 7, wherein the water-containing gel layer is reacted by spraying the water-soluble urethane prepolymer and the water separately and simultaneously onto the surface of the pile and mixing them. 9 Applying an alkaline substance to at least a portion of the surface of the pile, coating the alkaline substance with a water-soluble urethane prepolymer, and then applying the alkaline substance to at least a portion of the pile surface, and then coating the pile with the water-soluble urethane prepolymer. A treatment method for extracting a pile, comprising burying said pile in the ground so as to be located below the groundwater level.