JPH07279153A - Ground improving pile forming device - Google Patents

Abstract

PURPOSE:To provide a foundation improving material uniformized in diameter and degree of consolidation over the whole length and having good draining property by forming a slide layer consisting of a high molecular material on a casing inner circumferential surface. CONSTITUTION:A polyethylene material excellent in surface sliding property and impact resistance which has an average molecular weight of at least a bout 1,000,000 is rolled, and fitted into a casing 1 to form a slide layer 4. The casing 1 is intruded to a prescribed depth of the ground, a prescribed quantity of a foundation improving material S is put into the casing 1, a compressed air is supplied by an air supplying nozzle 10, and the improving agent S is discharged into the ground while pulling out the casing 1 in the pressurized state to form a foundation improving pile P. The foundation improving agent S is continuously discharged into the ground without adhesion and remaining on the casing 1 inner circumferential surface side or clogging in the course by its dead weight and the surface sliding effect of the slide layer 4. Thus, a foundation improving pile uniformized in diameter and degree of consolidation and having good draining property can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention introduces a ground improvement material composed of sand, gravel, crushed stone, slag, etc. into a casing penetrated into soft ground, and pulls out the casing to improve the ground inside. The present invention relates to a soil improvement pile device for discharging a material from a lower end of a casing into the soil to create a soil improvement pile.

[0002]

2. Description of the Related Art In this type of ground improvement pile forming device, a casing is penetrated to a predetermined depth in the ground by using an exciter, and the ground improvement material is put into the casing from a hopper at the upper end of the casing. After that, by pulling out the casing, the ground improvement material inside the casing flows down due to its own weight, is discharged into the ground from the lower end of the casing, and forms a ground improvement pile in the ground.

By the way, in the conventional ground improvement pile forming device, a steel pipe (steel pipe for general structure) is used as a casing. However, such a steel pipe generally has poor surface slipperiness and sand or the like adheres thereto. Since it is easy, the flow dischargeability of the ground improvement material at the time of pulling out the casing is poor, so that the inside of the casing may be clogged, which lowers the workability and can form a good ground improvement pile in the ground. In addition, since the inner surface of the steel pipe is easily rubbed by sand or the like when the ground improvement material is put into the casing or when the casing is pulled out, and rust is likely to be generated along with it, the flow discharge property is further deteriorated and the casing is worn. There is a problem saying that it hasten it.

Further, in this type of ground improvement pile forming device,
Generally, after the soil improvement pile is put into the casing, when the casing is pulled out, compressed air is supplied from above the inside of the casing to pressurize the inside of the casing, and the pressurizing action of this air improves the flow dischargeability of the soil improvement pile. I try to raise it. In this case, the pressure inside the casing is 5
If the pressure is as high as ~ 6 kgf / cm ² , the flow discharge property of the ground improvement material will certainly improve, but if there is a very weak part locally in the ground where the casing has penetrated, it will be discharged from the casing. The soil improvement material that is forming a pile bulges laterally in the relevant part, and the diameter and the pressure density become extremely uneven in the length direction of the pile, resulting in the problem that a good soil improvement pile cannot be constructed. .

In view of the above problems of the conventional apparatus, the present invention has a good flow discharge property of the ground improvement material at the time of pulling out the casing, can efficiently form good ground improvement piles in the ground, and An object of the present invention is to provide a ground improvement pile forming device capable of significantly improving durability.

[0006]

According to the first aspect of the present invention, the ground improving material S is put into the inside of the casing 1 penetrating into the ground, and the ground improving material inside the casing 1 is pulled out while the casing 1 is pulled out. S is discharged into the ground and the ground improvement pile P
In the ground improvement pile forming device configured to form the above, the sliding layer 4 made of a polymer material is formed on the inner peripheral surface of the casing 1.

According to claim 2, the sliding layer 4 is made of polyethylene having an average molecular weight of about 1,000,000 or more.

According to a third aspect of the present invention, the sliding layer 4 is formed by sticking a plate material made of a polymer material having a required thickness along the inner peripheral surface of the casing.

According to a fourth aspect of the present invention, a plurality of through holes 5 are provided in the casing at appropriate intervals, and an anchor portion 6 made of the same material as the polymeric material plate member is integrally formed with each of the through holes 5. It is characterized by being done.

According to a fifth aspect of the present invention, the sliding layer is formed by coating the inner peripheral surface of the casing with a polymeric material to a required thickness.

[0011]

According to the first aspect of the present invention, after the casing 1 is penetrated to a predetermined depth in the ground and then the casing 1 is pulled out, the ground improvement material S introduced into the casing 1
Due to its own weight and the surface slippery effect of the sliding layer 4 formed on the inner peripheral surface of the casing 1, the material smoothly flows down without adhering to and remaining on the inner peripheral surface of the casing 1 or causing clogging on the way. The ground improvement pile P is discharged continuously from the lower end of the casing 1 into the ground without interruption, whereby the diameter and the pressure density are uniform over the entire length and the drainage property is good.

The sliding layer 4 covers and protects the inner peripheral surface of the casing 1 and prevents the casing 1 from being worn and corroded.

In the second aspect, since the sliding layer is made of polyethylene having an average molecular weight of about 1,000,000 or more, the sliding layer 4 has an excellent surface smoothness, and the fluidity of the ground improvement material is improved. In addition to being extremely good, the inner peripheral surface of the casing 1 can be covered and protected, and the durability of the casing 1 can be remarkably improved. At the same time, the sliding layer 4 itself, its excellent wear resistance, impact resistance and chemical resistance. As a result, good surface smoothness can be maintained without being easily worn or corroded.

According to the third aspect, the sliding layer 4 can be easily formed by adhering a plate material made of a polymer material having a required thickness along the inner peripheral surface of the casing 1.

According to the present invention, when a plate material made of a polymer material is attached along the inner peripheral surface of the casing 1 to form the sliding layer 4, the sliding layer 4 is anchored by the anchor portion 6. It is fixed integrally with and does not peel off from the casing 1.

According to the present invention, when the sliding layer is formed by coating the inner peripheral surface of the casing with a polymer material to a required thickness, the sliding layer is formed and at the same time the sliding layer is formed in the casing. Since it is integrally fixed to the peripheral surface, it is not necessary to provide a special fixing means.

[0017]

EXAMPLES Examples will be described with reference to the drawings.
FIG. 1 shows a ground improvement pile forming apparatus according to the present invention. In FIG. 1, reference numeral 1 denotes a cylindrical casing having a hopper 2 on an upper portion thereof, and a vertical vibration of a vibrator 3 provided at an upper end portion thereof. It is designed to penetrate into the ground. A sliding layer 4 made of a polymer material is formed on the inner peripheral surface of the casing 1. Note that this device is suspended and supported by a lifting operation wire (not shown) that is suspended from the top of a reader (not shown).

The sliding layer 4 is made of so-called ultra high molecular weight polyethylene having an average molecular weight of about 1,000,000 or more.
Excellent surface slipperiness, impact resistance, abrasion resistance, and chemical resistance (corrosion resistance). The sliding layer 4 is formed by adhering a plate material of the above-mentioned ultra-high molecular weight polyethylene with a required thickness along the inner peripheral surface of the casing 1.

In order to form the sliding layer 4, the plate material made of the ultra-high molecular weight polyethylene having a required length, width and thickness is rolled into a cylindrical shape which can be fitted into the casing 1. It can be formed by inserting it inside and adhering it along the inner peripheral surface of the casing 1. As the plate material made of the ultra high molecular weight polyethylene, a commercially available material can be used. In this case, for example, a material known as Somalite which is a registered trademark of Somar Kogyo Co., Ltd. is preferable. The somalite ultra high molecular weight polyethylene has an average molecular weight of about 2,000,000 or more, and has extremely excellent properties such as slipperiness, non-adhesiveness, abrasion resistance and chemical resistance.

In this case, since the above-mentioned cylindrical plate material made of ultra-high molecular weight polyethylene is easily separated from the inner peripheral surface of the casing 1 simply by aligning it with the inner peripheral surface of the casing 1, this cylindrical plate material is Prior to inserting the casing 1 into the casing 1, a plurality of through holes 5 having, for example, a wedge-shaped cross section are provided in advance in the casing 1 at required intervals as shown in FIG. 2, and the cylindrical plate member is inserted into the casing 1. After that, a chip (small piece) of the same material as the above-mentioned ultra high molecular weight polyethylene plate material is inserted into each through hole 5, and the chip is melted in the through hole 5 by heating with a burner or the like, As shown in FIG. 2, an anchor portion 6 integrated with the cylindrical plate member inserted in the casing 1 is formed, and the anchor portion 6 fixes the sliding layer 4 to the inner peripheral surface of the casing 1 in a fixed state. It can be.

Further, without using the tip as described above, a flame is blown into the through hole 5 provided in the casing 1 by a burner or the like to melt the surface portion of the sliding layer 4 facing the through hole 5, The anchor portion having the same function as that of the anchor portion 6 can also be formed by fixing the surface fusion portion to the inner peripheral wall portion of the through hole 5. Even if the through hole 5 is not provided in the casing 1 and the anchor portion 6 is formed in the through hole 5 as described above, the cylindrical high-molecular-weight polyethylene plate material is rolled into a casing 1 via an adhesive. You may make it adhere | attach on the inner peripheral surface of.

Further, as shown in FIGS. 1 and 2, a steel stopper ring 7 is provided at both upper and lower ends of the inner peripheral surface of the casing 1.
Are fixed by welding so as to contact the upper and lower end surfaces of the sliding layer 4 made of the ultra-high molecular weight polyethylene plate material, and the retaining ring 7 prevents the sliding layer 4 from coming out of the casing 1.

In forming the sliding layer 4 of the plate material made of ultra-high molecular weight polyethylene, one plate material may be used and it may be attached along the entire inner peripheral surface of the casing 1. If the casing 1 has a relatively large diameter and length, and there is no large-scale commercially available product that can adhere the inner peripheral surface of the casing 1 with one sheet, a plurality of small-sized plate materials may be appropriately used. It suffices to extend the casing 1 and attach it to the inner peripheral surface of the casing 1. As shown in FIG. 1, since a hopper 2 is provided at the upper end of the casing 1 and the base end of the hopper 2 is opened, the plate material may be cut through the opening 8 as appropriate. .

In FIG. 1, reference numeral 9 denotes an opening / closing valve provided inside the hopper 2, which is normally held in a closed position as shown by a solid line by a spring (not shown), and the hopper 2 is grounded. When the improving material is introduced and flows down into the hopper 2, it is opened by its flow pressure. Reference numeral 10 is an air supply nozzle for supplying compressed air into the casing 1 when the on-off valve 9 is closed.

In the use of the ground improvement pile forming device having the above-described structure, first, with the device suspended from the top of the leader by the lifting operation wire, the exciter 3 is operated, While vibrating the casing 1 vertically,
The casing 1 is penetrated into the ground while paying out the lifting operation wire. Then, when the casing 1 reaches the ground entry predetermined depth, the operation of the vibration exciter is stopped, and the ground improvement material S made of, for example, sand is fed into the casing 1 from the hopper 2 in a required amount. Incidentally, casing 1
The ground improvement material S may be added to the casing 1 when the casing 1 penetrates into the ground.

Thus, the ground improvement material S is provided inside the casing 1.
After feeding in, compressed air is supplied by the air supply nozzle 10 to pressurize the inside of the casing 1 to about 1 kgf / cm ² while winding the lifting operation wire,
While pulling out the casing 1, the ground improvement material S inside the casing 1 is discharged from the lower end into the ground to form ground improvement piles (sand piles) P. At this time, the ground improvement material S inside the casing 1 has its own weight and the pressing action by the above-mentioned pressurized air, and in particular, due to the excellent surface smoothness effect of the sliding layer 4 formed on the inner peripheral surface of the casing 1,
Without adhering and remaining on the inner peripheral surface side or causing clogging in the middle, it extremely smoothly flows down and is discharged continuously from the lower end of the casing 1 into the ground without interruption, which results in a uniform diameter over the entire length. Good quality ground improvement piles (sand piles) P that are appropriately consolidated and have good drainability are efficiently formed in a short time.

Further, in this case, since the inside of the casing 1 is maintained at a low pressure of about 1 kgf / cm ² , even if a very weak portion exists locally in the ground where the casing 1 penetrates, There is no fear that the ground improvement material S being extruded from the lower end of the casing 1 to form a pile will swell in the relevant portion, so that the ground improvement pile P having a uniform diameter and pressure density over the entire length can be formed. .

Further, in this ground improvement pile forming apparatus, the sliding layer 4 formed on the inner peripheral surface of the casing 1 has an average molecular weight of about 1
Since it is made of so-called ultra-high-molecular-weight polyethylene of 1,000,000 or more, its excellent surface slipping effect makes it possible to improve the flow dischargeability of the ground improvement material S at the time of pulling out the casing as described above, while the sliding layer 4 is Casing 1
It is possible to improve the durability of the casing 1 by covering and protecting the inner peripheral surface thereof, and the sliding layer 4 itself and the sliding layer 4 easily wear due to its excellent wear resistance, impact resistance and chemical resistance. Since it does not corrode or corrode, it can be used for a long time while maintaining good surface smoothness.

FIG. 3 shows an apparatus 11 for testing the surface slipperiness of the sliding layer 4, that is, the slipperiness, and the results of the test performed by this apparatus 11 are shown in FIG. In this test apparatus 11, a rocking base 13 is pivotally mounted on a base 12 so that the tilt angle can be adjusted, and three kinds of test plates A, B and C for forming a sliding layer are sequentially mounted on the rocking base 13. Put. Then, the ground improvement material sample 14 (in this case, sand) in which the water content has been adjusted is filled in the short cylindrical pipe 15, and the bottom portion of the filled sand 15 is t (2) from the lower end of the pipe 15.
(mm), the ground improvement material sample 14 (sand) slides down when it is placed on each of the test plates A, B, C and brought into close contact therewith, and the rocking base 13 is gradually inclined from the horizontal state. Measure the angle θ. Here, among the test plates A to C, A is SS41 (carbon steel plate for general structure), and B is
SUS304 (stainless steel plate) and C are plate materials of ultra high molecular weight polyethylene (registered trademark Somalite).

Referring to the test results shown in FIG. 4, the common point to all of the three test plates A to C is that the smaller the water content of the ground improvement material sample 14 (sand), the smaller the slip start angle, and therefore the slip. You can see that it is good. The minimum slip start angle of the test plate A is about 25 degrees, the test plate B is about 15 degrees, and the test plate C is about 10 degrees. Therefore, from this test result, it is understood that the test plate C, that is, the plate material of the ultrahigh molecular weight polyethylene (registered trademark Somalite) has the best slipperiness.

In the above embodiments, the sliding layer 4 formed by adhering a plate material made of a polymer material having a required thickness along the inner peripheral surface of the casing 1 has been described, but the sliding layer according to the present invention is described. Can be formed by coating the inner peripheral surface of the casing with a polymer material to a required thickness. According to the sliding layer formed by such coating, since the sliding layer can be integrally fixed to the inner peripheral surface of the casing at the same time when the sliding layer is formed,
Easy to manufacture. Further, the sliding layer according to the present invention can be formed not only by such a coating method but also by a molding method using a molding die.

[0032]

According to the first aspect of the present invention, since the sliding layer made of the polymer material is formed on the inner peripheral surface of the casing, the ground improving material inside the casing is pulled out of the sliding layer when the casing is pulled out. Due to the surface lubricity effect, it does not adhere and remain on the inner peripheral surface of the casing, or it does not clog in the middle, it flows down smoothly and is discharged continuously from the lower end of the casing into the ground without interruption, and therefore over the entire length. It is possible to form a good quality soil improvement pile having a uniform diameter and compaction density and good drainability, and it is possible to improve workability. Further, when the inside of the casing is pressurized, the soil improvement material can be sufficiently discharged at a low pressure of about 1 kgf / cm ² . Further, since the inner peripheral surface of the casing is covered and protected by this sliding layer, it is possible to prevent the casing from being worn and corroded and to improve its durability.

According to the second aspect of the present invention, since the sliding layer is made of polyethylene having an average molecular weight of about 1,000,000 or more, the excellent surface smoothness effect makes it possible to improve the flow dischargeability of the ground improvement material when the casing is pulled out. , This sliding layer can coat and protect the inner peripheral surface of the casing and significantly improve the durability of the casing, and the sliding layer itself, due to its excellent wear resistance, impact resistance and chemical resistance, It does not easily wear or corrode, maintains good surface smoothness, and can be used for a long period of time.

According to the third aspect, since the sliding layer is formed by adhering a plate material made of a polymer material having a required thickness along the inner peripheral surface of the casing, a commercially available product as the plate material made of the polymer material is used. It can be used and the sliding layer can be formed easily and inexpensively.

According to the fourth aspect, when the plate material made of the polymer material is stretched along the inner peripheral surface of the casing to form the sliding layer, the sliding layer is integrally fixed to the casing by the anchor portion. Therefore, the sliding layer does not peel off from the casing.

According to the fifth aspect, when the sliding layer is formed by coating the inner peripheral surface of the casing with a polymer material to a required thickness, the sliding layer is formed and the sliding layer is formed at the same time. Since it is integrally fixed to the inner peripheral surface, it is not necessary to provide a special fixing means, and the sliding layer can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a ground improvement pile building device showing an embodiment of the present invention.

FIG. 2 is an enlarged detailed vertical sectional view of a casing in which a sliding layer is formed on an inner peripheral surface.

FIG. 3 is an explanatory view of an apparatus for testing the slipperiness of various materials used for the sliding layer.

FIG. 4 is a graph showing the test results of the slipperiness test apparatus of FIG.

[Explanation of symbols]

 1 Casing 2 Hopper 4 Sliding layer 5 Through hole 6 Anchor part S Ground improvement material P Ground improvement pile

Claims (5)

[Claims] 1. A ground improvement material is put into a casing that penetrates into the ground, and the ground improvement material in the casing is discharged into the ground while pulling out the casing to form a ground improvement pile. In the ground improvement pile forming device, a slip layer made of a polymer material is formed on the inner peripheral surface of the casing, and the ground improvement pile forming device. 2. The ground improvement pile building device according to claim 1, wherein the sliding layer is made of polyethylene having an average molecular weight of about 1,000,000 or more. 3. The ground improvement pile forming device according to claim 1, wherein the sliding layer is formed by adhering a plate material made of a polymer material having a required thickness along the inner peripheral surface of the casing. 4. The casing is provided with a plurality of through holes at appropriate intervals, and an anchor portion made of the same material as the polymeric material plate material is integrally formed with each of the through holes.
The soil improvement pile building device described in. 5. The ground improvement pile forming device according to claim 1, wherein the sliding layer is formed by coating a polymer material on the inner peripheral surface of the casing to a required thickness.