JP7228239B2 - How to restore the ground - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for restoring ground on which columnar improvements have been constructed by the soil cement column construction method.

When constructing a building or structure on the ground, it is often the case that pile driving and ground improvement are carried out in advance to prevent subsidence, and there are various types of piles such as iron, wood, and concrete. There are various embedding methods. Various technologies have also been developed for soil improvement, one of which is the soil cement column construction method. This construction method involves injecting a cement-based solidification material and water into the ground, mixing them with existing earth and sand, and forming a columnar improvement section (soil cement column) with an almost circular cross section. It can be constructed, produces little noise and vibration during construction, and is widely used mainly in residential applications.

As an example of technological development related to the soil cement column construction method, Patent Document 1 below can be cited. This document discloses a method for constructing and removing a soil cement column, which is characterized by being easy to construct and remove. Specifically, during the construction of a soil cement column (hereinafter referred to as column), a steel pipe (support and guide pipe) is inserted into the center of the column, and using this as a guide, a stirring rod penetrated into the ground is rotated. When pulled up, a uniform and good quality column can be constructed. Also, when removing the column, by embedding the hollow auger using the steel pipe as a guide, the cutting bit at the tip of the auger cuts the column without escaping, and the entire column can be surely destroyed.

The following patent document 2 discloses a widening drilling device for building a soil cement composite pile (soil cement column). In this document, when constructing a soil-cement synthetic pile, a widening excavator and a hollow pipe are embedded in the ground, and the tip of the widening excavator protrudes from the hollow pipe. The widening excavation blade, which expands in diameter from the widening excavator, reaches the outside of the hollow pipe and excavates the surrounding ground. In addition, by discharging hardening grout from near the tip of the widening excavator and mixing it with the ground, soil-cement synthetic piles are built one by one. In order to pull up only the widening excavation device while leaving the hollow pipe after construction, it has a function to reduce the diameter of the widening excavation blade. This diameter reduction is achieved by supporting the widened excavation blade with a swing shaft, and the swing shaft is tilted with respect to the rotation shaft.

Moreover, Patent Documents 3 and 4 are listed as examples of techniques related to the removal of soil cement columns. Among them, Patent Document 3 discloses a method for restoring the ground in which a columnar reformed portion (soil cement column) is formed. A grab bucket is inserted into the inside of the pit, and the reformed column is crushed and discharged repeatedly. After that, refilling materials such as gravel are repeatedly put in and tamped down, and finally the casing is pulled up to restore the ground. In this method, almost all of the original soil-cement columns can be removed, and the backfilling material can be tamped down to prevent loosening of the ground.

Patent Document 4 discloses an excavation head capable of easily crushing a columnar improved pile (soil cement column) buried in the ground. This excavation head has a structure in which a spiral excavation wing is provided on the side peripheral surface of the rotating shaft. A small rod-shaped bit is attached to the tip of the excavation wing, and the outer periphery of the excavation wing protrudes in the excavation direction. A leading pawl is attached. The leading claw protrudes further toward the tip side than the small bit, and the turning radius of the tip of the leading claw is set larger than the radius of the column-shaped improved pile. As a result, since the leading claw rotates about the solidified improved columnar pile as an axis, it is possible to prevent misalignment of the excavating head and easily crush the improved columnar pile.

Japanese Unexamined Patent Application Publication No. 2012-21310 JP 2005-220512 A JP 2017-78261 A Japanese Patent No. 6435077

As described above, the column-shaped improved part is widely used mainly in small-scale buildings such as houses, and it is necessary to suppress noise and vibration as much as possible so as not to deteriorate the surrounding environment even when crushing it. In addition, crushing work is often performed in confined spaces, and it is necessary to consider transportation of equipment and obstacles to traffic during work. Therefore, it is desirable to reduce the size of the equipment used for crushing as much as possible, suppress noise and vibration, and reduce energy consumption from the viewpoint of cost reduction.

Due to the nature of the improved columnar portion, the degree of compaction is often non-uniform. Therefore, at the time of crushing, the embedded drill or the like bends to avoid the hard region, causing a large misalignment, and there is a possibility that a part of the columnar improved portion remains without being crushed. In order to prevent such misalignment, it is possible to use a casing as in Patent Document 3, but the casing has a larger diameter than the columnar improved portion, and it takes time and effort to embed and pull up the casing, making it difficult to work. It is unavoidable to increase the size of the equipment to be used, and there is a disadvantage in terms of cost reduction.

Moreover, in Patent Document 4, only the columnar improved pile (columnar improved portion) is crushed and not removed. As a result, no casing is required, making it easier to reduce costs. However, in this technology, in addition to crushing the entire cross section of the improved columnar pile at almost the same time, to prevent misalignment, a large-diameter pre-claw that exceeds the diameter of the improved columnar pile is used. Therefore, the equipment tends to be large. Under these circumstances, there is a long-awaited technology that can reduce the amount of crushed material at one time, reduce the size of equipment, and reduce energy consumption for crushing the improved columnar part.

The present invention was developed based on this situation, and after the column improvement part is constructed by the soil cement column construction method, it is possible to restore the ground to its original state at low cost while suppressing the impact on the surrounding environment. The purpose is to provide a method.

A first aspect of the invention for solving the above-mentioned problem is a method for restoring ground by crushing a columnar improved portion with an excavation drill, wherein the excavation drill is a helical cutting tool that surrounds the side peripheral surface of the central shaft. A rod-shaped diameter-enlarging claw is oscillatably attached near the outer peripheral portion of the cutting tool, one end side of the diameter-expanding claw is supported by the cutting tool, and the other end side is the circumference of the central axis When the center shaft rotates forward, the diameter-enlarged pawl comes into contact with the improved columnar portion and falls down in the circumferential direction. When the blade is reversed, the diameter-enlarging pawl comes into contact with the improved columnar portion and protrudes in the radial direction, and the diameter of the outer peripheral portion of the cutting tool is smaller than the diameter of the improved columnar portion, and the expanded diameter When the claw protrudes in the radial direction, the diameter of the outer edge thereof is larger than the diameter of the improved columnar portion. In the process of reversing and pulling up the excavating drill after the vicinity thereof has been crushed, the ground restoration method is characterized in that the outer edge side of the improved columnar portion is crushed by the diameter-enlarging claw.

The purpose of the present invention is to crush the improved columnar portion using a relatively small-diameter excavation drill. Considering that the object to be excavated is hard, this cutting tool consists of multiple rows like a multi-threaded screw. The tip side of the excavation drill faces the improved columnar part, and a long drive shaft is connected to the opposite side. Axial movement is achieved. As a matter of course, when the excavating drill is embedded in the ground, the entire drill is rotated and excavation is performed by the cutting tool, and this rotating direction is the "forward rotation".

The diameter-expansion claw is a bar-shaped blade incorporated in the vicinity of the outer peripheral portion of the spirally extending cutting tool, and forms a sharp blade along its long side. This blade has only one row for one diameter-expanding pawl, and the opposite side becomes a ridge instead of a blade. One end of the diameter-expanding claw is attached to the vicinity of the outer peripheral portion of the cutting tool via a pin or the like so that it can swing relative to the cutting tool. The range of this swing is limited to approximately 90 degrees between the state in which the diameter-enlarging claw extends along the circumferential direction and the state in which the diameter-expanding claw protrudes in the radial direction, with reference to the rotation direction of the central shaft, and the range exceeding this range. As for , the diameter-expanding pawl comes into contact with surrounding parts, and swinging is restricted. Note that the diameter-expanding pawl is arranged not near the tip of the cutting tool, but at a position slightly recessed therefrom.

The diameter-expanding pawl can be freely swung by an external force, and changes its posture upon contact with the ground (including the columnar improved portion). Specifically, when the excavating drill rotates forward and crushing is performed by the cutting tool, the diameter-expanding claw is pushed down by contact with the ground and assumes a posture along the circumferential direction of the central axis. As a result, the diameter-expansion claw is housed in the vicinity of the outer peripheral portion of the cutting tool, and the diameter-expansion claw does not exhibit its function, and crushed objects merely pass through its surroundings.

When the cutting tool reaches the lowest part of the improved columnar part, the improved columnar part is crushed into pebbles where the cutting tool has passed so far, and then the direction of rotation is reversed in order to smoothly pull up the excavating drill. At that time, when the tip of the diameter-expansion claw contacts the ground (including the columnar improvement part), the diameter-expansion claw is pulled out and protrudes in the radial direction, but its swing range is regulated. Therefore, the protruding state is maintained, and it bites into the columnar improvement that has not yet been crushed.

The diameter of the outer circumference of the helical cutting tool should be smaller than the diameter of the post refinement for which it is intended to be used. Therefore, if the excavation drill is placed near the center of the improved columnar portion and the excavated drill is gradually embedded, only the vicinity of the center of the improved columnar portion is crushed by the cutting tool, so the torque for driving the excavated drill is suppressed. can. When the tip of the excavating drill reaches the lowest part of the improved columnar portion, the excavating drill is reversed and gradually pulled up.

Regarding the diameter expansion claw, when it protrudes in the radial direction due to contact with the ground, the diameter of the outer edge must exceed the diameter of the improved column. Can be crushed. In order to suppress bending of the central axis due to imbalance in reaction force, it is desirable to arrange a plurality of diameter-expanding claws at equal angles. In addition, the diameter-expanding pawl is arranged at a position recessed from the tip of the cutting tool. Therefore, when burying the excavation drill, it is made to reach a position slightly deeper than the bottom of the columnar improved portion so that the entire columnar improved portion can be crushed.

In this way, by using excavation drills equipped with diameter-expanding claws, the column-shaped improved part is crushed in two stages, embedding and pulling it up, so the torque during work is reduced and each part of the equipment can be made smaller. In addition, it is possible to downsize the engine that is the power source, reducing energy consumption as well as noise and vibration. In addition, the diameter-expanding jaws can reduce the size of the cutting tool and eliminate the need for conventional casings, making the equipment smaller. In the present invention, crushing is performed in two steps, near the center of the improved columnar portion and on the outer edge side, but this crushing can be achieved by only one up-and-down reciprocation of the excavating drill, so the working time does not increase.

The invention according to claim 2 is for suppressing the displacement of the excavating drill, and in the vicinity of the tip of the center shaft is provided an advanced shaft that protrudes beyond the tip of the cutting tool, and the end surface of the advanced shaft is provided with: A plurality of leading claws for crushing are provided. Since the excavation drill is held on the ground through the drive shaft and the rigidity of the drive shaft is limited, the excavation drill can be easily displaced in the radial direction of the drive shaft. Therefore, due to unevenness in the hardness of the improved columnar portion, the reaction force acting on the cutting tool is also biased, and eventually the excavating drill is displaced greatly from the center of the improved columnar portion, making it impossible to crush a part of the improved columnar portion. is also expected. In order to prevent this, a leading shaft projecting from the tip position of the cutting tool is provided, and a leading pawl is provided on it.

The advanced shaft is positioned as an extension of the central shaft, and may be integrally formed with the central shaft, or may be separately manufactured and integrated with the central shaft by welding or the like. Furthermore, the advanced shaft and the central shaft may have the same diameter, or the advanced shaft may be finished in a tapered conical shape to facilitate the discharge of crushed matter. A plurality of leading claws that actually crush the ground are provided on the end face of the leading shaft. The leading pawl is rod-shaped or plate-shaped with a size that can be arranged on the end face of the advanced shaft, and its base is firmly integrated with the advanced shaft.

The turning diameter of the leading shaft and leading jaw is much smaller than the turning diameter of the entire drill. Therefore, when the excavation drill moves forward, the resistance generated around the leading shaft and the leading jaw is also reduced, and even if there is uneven hardness in the improved columnar part, the leading shaft moves straight without being misaligned. . As a result, the whole excavation drill moves straight without misalignment using the advanced shaft as a guide, and the center of both the excavation drill and the improved columnar part always coincides, so that the entire improved columnar part can be crushed. be.

According to the third aspect of the invention, a series of excavations is made smoother, and a flow path is provided inside the center shaft and the leading shaft for injecting fluid around the leading claws. Characterized by The leading claws, cutting tools, and diameter-expanding claws generate a large amount of friction when crushing the improved columnar portion, which increases the torque for driving and accelerates the wear and deterioration of parts due to heat generation. Therefore, it is desirable to reduce friction and heat generation by injecting liquid or gas from near the tip of the excavation drill. In principle, the flow path is formed at the center of the central axis or the advanced axis, and a valve or the like can be incorporated to prevent foreign matter from entering.

As in the first aspect of the invention, the excavation drill for crushing the improved columnar portion is composed of a helical cutting tool that surrounds the central axis and a diameter-expanding claw attached near the outer periphery of the cutting tool. Crushes near the center of the improved columnar portion with a cutting tool, and crushes the outer edge side of the improved columnar portion with a diameter-expanding claw when pulling up the excavating drill. This gradual fracturing of the columnar improvement reduces the torque required to drive the drill during both embedding and lifting, reducing energy consumption as well as noise and vibration. come true.

In addition to reducing the size of the cutting tool with the diameter expansion claw, conventional casings are not required, and less equipment is required. Moreover, it is possible to make it smaller, so it can be easily transported and installed even in cramped spaces. It is easy to avoid traffic obstacles. In the present invention, the crushing is performed in two stages, when the excavation drill is embedded and when it is pulled up. In addition, since the swinging of the diameter expansion claw is realized only by the rotation of the excavation drill and the contact with the ground (including the columnar improvement part), no operating mechanism such as a link is required, and the structure and handling can be complicated. do not have.

As in the invention described in claim 2, an advanced shaft protruding from the tip of the cutting tool is provided near the tip of the central shaft, and a plurality of leading claws for crushing are provided on the end surface of the advanced shaft, thereby enabling excavation. In the vicinity of the tip of the drill, only a narrow area facing the advanced shaft is crushed, so the resistance generated around the advanced shaft and the leading claw is also small, and even if there is uneven hardness in the pillar-shaped improvement part, the advanced shaft can be crushed. will go straight without any misalignment due to its influence. As a result, the whole excavation drill moves straight without misalignment using the advanced shaft as a guide, and the center of both the excavation drill and the improved columnar part always coincides, so that the entire improved columnar part can be crushed. be.

As in the third aspect of the invention, a flow path for injecting fluid around the leading claws is provided inside the center shaft and the leading shaft, and by injecting water or the like at the time of crushing, the leading claws and the cutting tool can Friction and heat generated around the diameter expansion claw are alleviated. In addition, the torque required to drive the excavation drill is reduced, which can be expected to reduce energy consumption, noise and vibration. Furthermore, by adding various chemicals to the jetted fluid, harmful substances remaining in the ground can be rendered harmless.

FIG. 2 is a diagram showing the flow of the ground restoration method according to the present invention, in which the left side of the figure shows the step of embedding the excavation drill, and the right side of the figure shows the stage of pulling up the excavation drill. Figure 2 shows a detail of the drill of Figure 1;

FIG. 1 shows the flow of the restoration method of the ground G according to the present invention, and the ground G is formed with a columnar improvement portion C. As shown in FIG. Column-shaped improved part C is a soil cement column formed by a technique generally called the soil cement column construction method, which is made by mixing a cement-based solidification material with existing earth and sand, solidifying it into a columnar shape, and reinforcing bars, steel frames, etc. is not included. In addition, the existing earth and sand remains as it is on the outside of the columnar improved portion C.

An excavation drill 11 is used to crush the improved columnar portion C. As shown in FIG. The excavation drill 11 is composed of a round-bar-shaped center shaft 15 extending from the center and a spiral cutting tool 16 surrounding the side peripheral surface of the center shaft 15. The cutting tool 16 has three pieces of the same shape, similar to the three-start screw. They are arranged at equal angles. The tip of the cutting tool 16 is sharpened, and a cylindrical bit 17 is integrated therewith, so that crushing can be efficiently performed. However, the diameter of the outer peripheral portion of the cutting tool 16 is smaller than the diameter of the improved columnar portion C, and the crushing of the improved columnar portion C cannot be completed with the cutting tool 16 alone.

A U-shaped holder 23 is integrated in the vicinity of the outer peripheral portion of the cutting tool 16, and a rod-shaped enlarged diameter claw 22 is accommodated therein. One end side of the enlarged diameter claw 22 is attached to the holder 23 so as to be swingable, and the swinging range is approximately 90 degrees. Therefore, the other end side of the enlarged diameter pawl 22 may extend along the outer peripheral portion of the cutting tool 16 or protrude in the radial direction.

An upper portion of the central shaft 15 of the excavating drill 11 is connected to the drive shaft 41 via a joint 43 . The drive shaft 41 is a shaft for suspending the excavation drill 11 , and the upper portion of the drive shaft 41 is inserted into the holder 42 . A drive motor 44 is incorporated in the holder 42, and the drive shaft 41 can be freely rotated. Further, the holder 42 is incorporated in various construction machines (not shown) and can move up and down. This realizes embedding and pulling up of the excavation drill 11 . When transporting these equipment, the excavating drill 11 and the drive shaft 41 are separated by the joint 43, and the drive shaft 41 is removed from the holder 42 to reduce the space occupied as much as possible.

A leading shaft 31 is connected to the tip of the central shaft 15 . In this figure, the center shaft 15 and the leading shaft 31 are seamlessly integrated, and the range below the tip of the cutting tool 16 is called the leading shaft 31 . Furthermore, a cylindrical leading claw 32 is integrally welded to the end face of the leading shaft 31 in the same manner as the bit 17 described above. By fitting the advanced shaft 31 into the portion crushed by the leading claw 32, misalignment of the excavating drill 11 is regulated.

A tunnel-shaped flow path 18 penetrates through the center of the excavating drill 11, and by using this flow path 18 to inject a fluid F such as water near the leading claw 32, friction and heat generation during crushing are reduced. can be mitigated. Since the fluid F is supplied from a pipe 49 on the ground, a flow path 48 is also formed in the center of the drive shaft 41, and a joint 45 is provided above the drive shaft 41 for connection with the pipe 49. The joint 43 is also incorporated, and a flow path is secured inside. The jetted fluid F passes through the gaps between the crushed objects and reaches the cutting tool 16 and the diameter-enlarging claw 22, thereby reducing friction and heat generation there.

On the left side of FIG. 1, the stage of embedding the excavation drill 11 and crushing the center portion of the columnar improvement portion C is depicted, and after matching the center of both the excavation drill 11 and the columnar improvement portion C, it is held. The excavating drill 11 is embedded in the ground G while being rotated clockwise (normally) by the tool 42 . At the initial stage of embedding, only the leading claw 32 comes into contact with the improved columnar portion C, and only a very narrow range is crushed. The tip of 16 and the range in contact with bit 17 are crushed. Although the improved columnar portion C crushed into pebbles is placed on the upper surface of the cutting tool 16, most of it remains in the ground G without being discharged to the ground.

When the excavating drill 11 is embedded, the diameter-expansion claw 22 falls down in the circumferential direction due to contact with the surroundings. Therefore, the enlarged diameter claw 22 does not protrude greatly from the outer peripheral portion of the cutting tool 16 and does not participate in crushing at this stage. However, after the tip of the cutting tool 16 breaks through the lowermost portion of the improved columnar portion C, as depicted on the right side of FIG. go. At that time, the diameter-enlarging claws 22 protrude in the radial direction due to contact with the periphery, and the diameter-enlarging claws 22 crush the outer edge side of the improved columnar portion C. As shown in FIG. Since the diameter of the outer edge of the projecting enlarged diameter claw 22 is larger than the diameter of the improved columnar portion C, the improved columnar portion C can be completely crushed. Although the crushed improved columnar portion C remains in the form of pebbles, it is mixed with the surrounding ground G and restored to its original state.

FIG. 2 shows details of the drill 11 of FIG. A slightly smaller diameter shank 19 is formed on the upper portion of the central shaft 15 in order to incorporate the joint 43 of FIG. A portion of the central shaft 15 below the tip of the cutting tool 16 is called a leading shaft 31, and three leading claws 32 are attached to the end face thereof. Furthermore, the flow path 18 reaches the center of the end face of the advanced shaft 31, and a valve 38 is attached to prevent foreign matter from entering the flow path 18. As shown in FIG. The valve 38 opens when the internal pressure of the channel 18 increases, but closes the channel 18 when the external pressure increases.

The enlarged diameter pawl 22 is rod-shaped, and one of its opposed side end faces is a sharp wedge-shaped front face 26, and the other side end face is a not sharp back face 27, and the front face 26 corresponds to a blade. The rear surface 27 corresponds to a ridge, and the front surface 26 crushes the ground G and the columnar improvement portion C. A U-shaped holder 23 is integrated with the outer peripheral portion of the cutting tool 16, and a pin 24 penetrating the holder 23 attaches the diameter-expanding pawl 22 so as to be swingable. In addition, due to the relationship with the holder 23, the enlarged diameter claw 22 can be laid down toward the rear end side of the outer peripheral portion of the cutting tool 16, but cannot be laid down toward the opposite tip side.

Therefore, when the excavating drill 11 rotates forward, the rear surface 27 of the diameter-enlarging claw 22 contacts the columnar improved portion C or the like, and the diameter-expanding claw 22 falls down along the outer peripheral portion of the cutting tool 16. The claws 22 do not crush the improved columnar portion C or the like. On the other hand, when the excavating drill 11 is reversed, the front surface 26 of the diameter-enlarging claw 22 comes into contact with the ground G and the columnar improved portion C, so that the vicinity of the tip of the diameter-expanding claw 22 is pushed out and begins to be displaced with the pin 24 as a fulcrum. However, since the enlarged diameter claw 22 eventually comes into contact with the holder 23, the enlarged diameter claw 22 maintains the radially projecting state. In addition, when the excavating drill 11 is reversed, the front surface 26 of the diameter-enlarging claw 22 faces the ground G and the columnar improved portion C, and these are crushed.

11 drilling drill 15 center shaft 16 cutting tool 17 bit 18 flow path 19 shank 22 diameter expansion claw 23 holder 24 pin 26 front surface (diameter expansion claw)
27 back (of expanding claw)
31 advanced shaft 32 leading pawl 38 valve 41 drive shaft 42 holder 43 joint 44 drive motor 45 joint 48 flow path 49 pipe F fluid C columnar improvement part (soil cement column)
G Ground

Claims (3)

A method for restoring a ground (G) by crushing a columnar improvement part (C) with an excavation drill (11),
The excavation drill (11) is provided with a plurality of spiral cutting tools (16) surrounding the side peripheral surface of the central shaft (15), and rod-shaped enlarged diameter claws (22) are provided in the vicinity of the outer peripheral part of the cutting tools (16). It is attached so that it can swing freely,
One end of the diameter-expanding claw (22) is supported by the cutting tool (16), and the other end is capable of swinging in a range from the circumferential direction to the radial direction of the central shaft (15). When (15) rotates forward, the enlarged diameter pawl (22) comes into contact with the improved columnar portion (C) and falls down in the circumferential direction. The enlarged diameter claw (22) comes into a state of protruding in the radial direction upon contact with the improved columnar portion (C),
The diameter of the outer peripheral portion of the cutting tool (16) is smaller than the diameter of the improved columnar portion (C). larger than the diameter of part (C),
In the process of rotating the excavating drill (11) forward and embedding it in the ground (G), the vicinity of the center of the improved columnar portion (C) is crushed by the cutting tool (16), and the excavating drill (11) is reversed. A ground restoration method characterized by crushing the outer edge side of the columnar improved portion (C) with the diameter-enlarging claw (22) in the process of pulling up and pulling up. Near the tip of the central shaft (15), an advanced shaft (31) projecting beyond the tip of the cutting tool (16) is provided. 2. The ground restoration method according to claim 1, wherein a plurality of (32) are provided. 2. A channel (18) for injecting fluid around the leading claw (32) is provided inside the central shaft (15) and the leading shaft (31). Described ground restoration method.

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