JP7104870B1 - SOIL IMPROVEMENT METHOD AND EXCAVATOR FOR SOIL IMPROVEMENT - Google Patents

Abstract

[PROBLEMS] To provide a construction method for consolidating and efficiently constructing a drain hole (crushed stone pile) using crushed stone as a liquid countermeasure for sandy ground B. SOLUTION: A casing 1 provided with crushed stone inlets 12 at an appropriate vertical interval, an excavation rod 2 which is housed in the casing 1 and provided with an excavation part 22 having an excavation bit and a hold-down spiral blade at the lower end, and an excavation rod 2 at the upper end of the casing. The excavator, which is detachably mounted and configured with a connecting body 3 connected to the upper end of the excavation rod, is mounted on a predetermined excavator body A, and the casing 1 is erected on the ground C by excavation without soil discharge by the excavator. The crushed stone is loaded from the crushed stone inlet 12 of the casing, and the crushed stone is packed and compressed by the excavation part in stages according to the withdrawal of the casing, and the excavator is pulled out to construct the crushed stone pile D in the ground. [Selection drawing] Fig. 3

Description

TECHNICAL FIELD The present invention relates to a ground improvement method for countermeasures against ground liquefaction and an excavator used in the method.

As a ground improvement method for the purpose of liquefaction countermeasures, it is known to form crushed stone piles (drain holes) in soft ground to improve the drainage of the ground and reduce complete liquefaction during an earthquake. In order to construct the above-mentioned crushed stone pile in the ground, the casing is set up in the ground, the filling material (crushed stone) is thrown into the casing, the casing is pulled out leaving the crushed stone in the ground, and the crushed stone pile is constructed. There is.

The upsetting work of the casing, which is generally adopted when constructing drain holes (mainly sand piles) as a means of improving soft ground, consists of a casing with a drilling bit at the tip and a soil discharger placed in the casing. Means for discharging soil by combining augers (Patent Document 1), means for adopting a casing provided with a compression cam-shaped digging blade at the tip and standing up the casing by non-discharging excavation (Patent Document 2), A means for spirally press-fitting a casing provided with an openable/closable conical opening/closing door without excavation is known (Patent Document 3).

In addition, the filling work of crushed stone, sand, etc. is a means of pushing the filling material downward by reverse rotation of the excavation auger (Patent Document 1), and a means of conveying the filling material downward by a conveying part equipped with a spiral blade. (Patent Document 2), means for pushing a filler (sand) put into a casing with a water jet (Patent Document 3), and the like are known.

Japanese Patent Application Laid-Open No. 2000-154532. Japanese Patent Application Laid-Open No. 2006-316592. Japanese Patent Application Laid-Open No. 2000-110156.

The purpose of the present invention is to construct a crushed stone pile that serves as a drain hole by putting crushed stone into a casing that is placed in the ground as a countermeasure against ground liquefaction. Since it is assumed that sand piles will be constructed, the reversal of the excavated soil discharge auger (Patent Document 1) and the spiral blade for transport (Patent Document 2) are used to fill the casing with sand. In comparison, since crushed stone has low fluidity, the auger and the spiral blade portion for conveying impede crushed stone injection into the casing, preventing efficient injection of crushed stone.

In crushed stone piles, crushed stones must be sufficiently compacted. For this reason, crushed stone cannot be compressed simply by throwing crushed stone into the space in the casing as described in Patent Document 3.

Therefore, the present invention proposes a novel ground improvement method and an excavator for the same that can efficiently perform crushed stone pile construction work, and also realize filling and compression of input crushed stone and compression of the surrounding ground.

The ground improvement method according to claim 1 of the present invention includes a casing provided with crushed stone inlets at appropriate intervals in the vertical direction, and an excavation part embedded in the casing and equipped with an excavation bit at the lower end and a spiral blade that holds down just above the excavation bit. The drilling rod and the connecting body detachably attached to the upper end of the casing and connected to the upper end of the drilling rod are mounted on a predetermined excavator body, and the excavation unit performs non-discharge boring excavation. , The casing is set up in the ground, and the crushed stone is charged from the crushed stone inlet of the casing and the crushed stone is packed and compressed by the excavation part in stages in accordance with the withdrawal of the casing. is characterized by constructing

In addition, the ground improvement method according to claim 2 of the present invention is the above method, in which the charging and compression of crushed stone input by the excavation section is performed by releasing the connection between the connecting body and the casing, and pushing crushed stone by rotating the spiral blade of the excavation section. Alternatively, crushed stones are pushed in by vertical movement of the excavating section, or both.

A ground improvement apparatus according to claim 3 of the present invention is for realizing the above construction method, and is composed of a casing, an excavation rod that is inside the casing, and a connecting body that connects the excavation rod and the casing at the upper end of the casing. The casing comprises a cylindrical portion of a predetermined length provided with crushed stone inlets at suitable intervals in the vertical direction, and a cylindrical drive connecting portion that is detachably connected to the connecting body is provided at the upper end of the cylindrical portion, The drilling rod has, at the lower end of a shaft portion having a predetermined axial length corresponding to the casing, a drilling portion provided with a drilling bit and a spiral blade that holds down directly above the drilling bit and is provided so as to protrude from the tip of the casing by a predetermined length, The upper end of the shaft portion is provided with an upper end connecting portion that is connected to the connecting body, and the connecting body is connected to the connecting cylindrical body detachably fitted to the cylindrical drive connecting portion at the upper end of the casing, and the excavator body at the upper end. and a rod connecting portion at the lower end and connected to the connecting cylinder in a penetrating manner. It is characterized by

Then, the upper end of the drilling rod is connected to the connecting body (transmission shaft), the drilling rod is arranged in the casing, and the drive connecting portion at the upper end of the casing and the connecting body (connecting cylindrical body) are connected to integrate the drilling apparatus. and Next, the mounting portion of the linking body (transmission shaft) is connected to the rotary drive mechanism of a predetermined excavator (a well-known excavator equipped with a leader mast in the traveling machine and having a rotary drive mechanism that moves up and down along the leader mast). The excavator is attached to the ground by connecting it, and the prescribed ground improvement work is carried out.

The ground improvement work involves constructing crushed stone piles that will serve as drain holes in the ground. The excavator of the present invention is attached to the excavator body, the excavator is driven to rotate to excavate, and the entire excavator is inserted into the ground. do. In particular, the excavation and drilling described above is performed in a state in which the excavation portion protrudes from the lower end of the casing. Accordingly, sand excavation is performed by the excavation bit of the excavation section, and the excavated earth is held down and pushed out in the excavation direction by the spiral blades to prevent it from entering the casing. Compresses the surrounding ground (excavator).

After the excavation work is completed, the crushed stone is charged and the crushed stone is filled and compressed. Then, the excavation part is movable with the casing as it is, and the crushed stone is filled and compressed by vertical movement of the excavation part and pushing rotation by the spiral blade. The aforementioned crushed stone injection/filling compression is carried out in stages corresponding to the appropriate extraction of the casing. Filling and compaction is repeated as appropriate, and crushed stone is packed and compacted for the entire borehole (filling and compaction work). Therefore, when the excavator is pulled out of the excavated ground after completing the filling compression work, crushed stone piles that serve as drain holes are constructed in the ground. It will be.

According to a fifth aspect of the present invention, there is provided a ground improvement excavating apparatus, in which the connecting portion between the transmission shaft and the connecting cylinder in the linking body is connected to the transmission shaft so that the excavating portion extends from the lower end of the casing. It is set so that it can be protruded and installed in the casing, and it can be quickly carried out by the excavator. can be performed just outside the casing or inside the casing.

According to a sixth aspect of the present invention, there is provided an excavating apparatus for soil improvement, in which the driving connection portion between the connecting cylinder and the casing is released only at a predetermined relative angular position between the casing and the connecting cylinder. When the connecting cylinder (excavation rod) is rotated to a predetermined position while the casing is buried, the connection between the casing and the connecting cylinder is released. It is easy to transition to independent motion of the drilling rod while the casing remains stationary during filling and compression work.

A ground improvement excavator according to claim 7 of the present invention is any one of the excavators described above, and has a hole wall pressing portion provided with a pressing inclined surface corresponding to the rotation direction of excavation at an appropriate location on the outer peripheral surface of the casing. is provided to efficiently compress the hole wall of the borehole during excavation, resulting in compression of the soft surrounding ground itself, and during excavation and extraction (in the case of rotation in the excavation direction) Reduce the resistance of the perforated wall of the casing.

As described above, the present invention uses a drilling apparatus in which a drilling rod having a predetermined drilling portion at its tip is arranged in a casing to improve the efficiency of drilling work, and to compress the crushed stone input by the drilling portion. We were able to efficiently construct crushed stone piles packed with crushed stone for ground improvement.

BRIEF DESCRIPTION OF THE DRAWINGS The general view of the excavator of embodiment of this invention. Explanatory diagram of the construction process (excavators and hiragana characters indicate the order of construction). The same figure (crushed stone input). The same figure (filling compression work and extraction work of crushed stone). The same figure (explanatory diagram of excavation part operation at the time of filling compression of crushed stone). Explanatory drawing (exploded view) of the connecting body of the excavator. The same figure (connection state of the connecting cylinder and the transmission shaft). The same figure (the connection state of a connection body and a casing).

Next, embodiments of the present invention will be described. The drilling apparatus shown in the embodiment is composed of a casing 1 , a drilling rod 2 and a linking body 3 .

The casing 1 is formed of a tubular portion 11 having a length of, for example, about 5 m (appropriately longer than the length of the crushed stone pile to be constructed) and a diameter of about 50 cm. A drive connecting portion 13 is provided at the upper end, an excavating blade 14 is vertically provided at the lower end of the cylindrical portion, and a spiral ridge for excavation (excavation rotation: hereinafter referred to as a "forward rotation" spiral ridge for screwing the casing on the lower outer peripheral surface) ) 15, and hole wall pressing portions 16 provided with pressing inclined surfaces corresponding to the excavating rotation direction (positive rotation direction) are provided on the entire outer peripheral surface of the cylindrical portion 11 vertically and radially at appropriate intervals. .

A connecting projection 312 of a connecting cylinder 31 of the connecting body 3, which will be described later, is inserted into the drive connecting portion 13, and the connecting cylinder 31 moves in the forward (excavating) direction and reverse (extracting) directions. An inverted T-shaped groove 17 is formed to be in a locked state.

The drilling rod 2 has a shaft portion 21 of a predetermined length, a drilling portion 22 connected to the lower end thereof, and an upper end connecting shaft portion 23 connected to a transmission shaft body 32 of the connecting body 3 to be described later.

The excavation part 22 is provided with a spiral blade 222 (a spiral in the opposite direction to the spiral ridge 15 for excavation of the casing 1) that pushes the excavated material downward by rotating in the excavation direction on an excavation shaft 221 connected to the shaft part 21. A drilling bit 223 is provided vertically on the lower end face of the 222 .

The linking body 3 is composed of a linking cylinder 31 and a transmission shaft 32 . A connecting protrusion 312 that can be engaged with the inverted T-shaped groove 17 is provided.

The transmission shaft body 32 has a shaft part 321 having a sufficient length to vertically penetrate the connecting cylinder body 31. The upper end of the transmission shaft body 32 has a mounting part 322 to the rotary drive mechanism b of the excavator body A, and the lower end of the shaft part 321 has the excavation rod 2. A rod connecting portion 323 that connects with the upper end connecting shaft portion 23 is provided.

The connecting cylinder 31 and the transmission shaft 32 are connected by a connection part having a structure in which the vertical position can be changed. This embodiment corresponds to this by providing a connection part that can be selectively connected in multiple stages of upper and lower connection parts. Specifically, as a connecting structure, the transmission shaft 32 is provided with connecting arms 324a, 324b, and 324c projecting radially (in four directions) at upper, middle, and lower positions. is provided with a pin through hole 325, and the connecting cylinder 31 is provided with an upper lid portion 313 having an insertion hole through which the shaft portion 321 of the transmission shaft 32 and the connecting arm portions 324a, . Connection arm portion 324a on portion 313 .

Therefore, the connecting cylinder 31 and the transmission shaft 32 are arranged such that any one of the upper, middle and lower connection arm portions 324a, . . . It is connected and integrated by inserting a pin. Especially when connecting at the position of the upper connection arm portion 324a, the excavation portion 22 is made to project from the lower end of the casing 1 to correspond to the excavation work, and the middle portion is connected. When connecting at the position of the connecting arm portion 324b or the lower connecting arm portion 324c, the excavating portion 22 is accommodated in the casing 1 to accommodate crushed stone filling and compression work.

The above-described members are assembled in a predetermined manner to form an excavating device, and the excavating rod 2 arranged in the casing 1 is connected to the upper end connecting shaft portion 23 and the rod connecting portion 323 of the transmission shaft body 32 of the connecting body 3. The transmission shaft 32 is connected to the connecting cylindrical body 31 at a predetermined connecting portion, and the connecting cylindrical body 31 is fitted to the cylindrical drive connecting portion 13 of the casing 1 in the above-described connected state, and the connecting protrusion 312 is fitted. is inserted into the inverted T-shaped groove 17 and rotated, the linking body 3 and the casing 1 are engaged, and the drilling apparatus is integrated.

The connecting cylinder 31 and the transmission shaft 32 of the connecting body 3 determine the connection arm portions 324a, 324b, 324c connected to the connection receiving portion 314 in order to determine the mounting position of the excavating portion 22 in the excavating device. However, as described above, at the start of excavation, the upper connecting arm portion 324a is pin-connected to the connection receiving portion 314 so that the excavating portion 22 protrudes from the lower end of the casing 1, and later the middle connecting arm portion 324b or the lower connecting arm portion is connected. The arm portion 324 c is connected to the connection receiving portion 314 .

In the construction method of the present invention, an excavator constructed by combining the above members is attached to a predetermined excavator body A, and when constructing a drain hole (crushed stone pile) D formed of crushed stone C in the ground B, crushed stone is compressed . It is realized.

The excavator A to be used is a traveling machine equipped with a leader mast a, and a rotary drive mechanism b that connects and rotates an excavator is attached to the leader mast a, and the excavator is suspended from the rotary drive mechanism b. It is connected and moved up and down along the leader mast a for excavation work.

Then, using the excavating equipment, an excavator for inserting the casing 1 into the ground B and a filling compactor for filling and compressing the crushed stone C by putting crushed stone C into the casing 1 are successively carried out to form a predetermined drain hole. (crushed stone pile) Construct D.

The excavator connects and attaches the mounting portion 322 of the transmission shaft body 32 of the integrated excavator to the rotary drive mechanism b of the excavator A (Fig. 2A), and installs the entire excavator ( The casing 1, the drilling bit 2, and the connecting body 3) are rotated and lowered to drill the ground (Fig. 2).

The excavator excavates the ground below with the excavation bit 223, suppresses the excavated soil with the spiral blade 222, and excavates while preventing the excavated soil from entering the casing 1, thereby performing non-excavation excavation. Furthermore, the rotation of the casing 1 also acts as an excavating force due to the spiral ridge 15 of the casing 1, and the resistance between the casing 1 and the hole wall is reduced by the hole wall pressing portion 16.

When the excavation work is completed, the crushed stone is charged and the crushed stone is packed and compressed. Crushed stone C is charged into the casing 1 through a crushed stone inlet 12 exposed near the ground surface of the casing 1, and the excavation rod 2 is used to fill and compress the crushed stone.

When the connecting member 3 and the excavating rod 2 are rotated in a predetermined direction with respect to the casing 1 (the connecting protrusion 312 is positioned at the center of the inverted T-shaped groove 17=disconnected position), the crushed stone C is charged and compressed by the excavating rod 2. , the drilling rod 2 and the linking body 3 are disconnected from the casing 3, so that the drilling rod 2 and the linking body 3 can be vertically moved and rotated, and the middle connecting arm 324b or the lower connecting arm It enables the connection of the portion 324 c to the connecting cylinder 31 .

The crushed stone filling and compressing work sequentially connects and disconnects the drilling rod 2 and the connecting body 3 from the casing 3, moves the entire drilling rig or the drilling rod 2 and the connecting body 3 up and down, and drives them to rotate. According to step 3, the crushed stone C is put into the casing 1 from the crushed stone inlet 12 exposed on the ground surface, step by step (Fig. 4E), and the drain hole ( Crushed stone pile) D is constructed (Fig. 4 O).

Specifically, when the excavation section 22 is lifted into the casing 1 at the end of excavation (FIG. 3), and the crushed stone C is thrown into the casing 1 from the crushed stone input port 12 of the casing 1, the crushed stone is placed in the excavation location (excavation hole) E. When C falls and the excavated hole E is filled with the crushed stone C, the crushed stone is compressed.

That is, when the excavating section 22 is raised to a position where the connecting protrusion 312 of the connecting cylinder 31 is pulled out from the inverted T-shaped groove 17, crushed stone C is thrown in, and the excavating section 22 is appropriately rotated (rotated forward) for excavation, the casing is Crushed stone C is fed (pushed) into the excavated hole E below 1, and is further moved up and down as necessary to push crushed stone C into the excavated hole E. The crushed stone C is compacted (Fig. 5-1).

When crushed stone is put into the first excavation hole E, and when the crushed stone is charged and compressed, the joint between the connecting cylinder 31 and the transmission shaft 32 as they were during excavation may be used as the upper connecting arm 324a. 324b. When the excavator is pulled out and when the crushed stone is put in/filled and compressed after the next time, the connecting portion of the connecting cylinder 31 and the transmission shaft 32 is set to the middle connecting arm portion 324b.

The connecting portion of the connecting cylinder 31 and the transmission shaft 32 is used as a middle connecting arm portion 324b, the connecting cylinder 31 is fitted into the driving connecting portion 13, and the excavated portion 22 is set at a position substantially facing the tip opening of the casing 1, When the excavating rod 2 is reversely rotated (withdrawn), the connecting projection 312 is engaged with the inverted T-shaped groove 17, and the excavating apparatus is withdrawn by a predetermined distance while rotating the entire excavating apparatus in the reverse direction.

When the excavator is pulled out by an appropriate distance, a new excavation hole portion E1 not filled with crushed stone C is exposed, and crushed stone is charged and packed and compressed in the same manner as described above (Fig. 5-2). By repeating this several times until the entire excavator is pulled out, the drain hole (crushed stone pile) D is constructed.

In addition, when the lower connecting portion 324c is employed as the connecting portion between the connecting cylinder 31 and the transmission shaft 32, particularly when the excavating device is pulled out and the crushed stone is put in/filled and compressed, the position of the excavated portion 22 in the casing 1 is changed. . Therefore, when the excavator is pulled up, as shown in FIG. This means that the filling and compression work can be carried out inside the casing 1, and can be carried out while preventing the collapse of the hole wall of the excavation hole E during the crushed stone filling and compression work.

When the crushed stone C is filled and compressed as described above and the casing is finally pulled out, crushed stone piles D that will be drain holes are constructed in the ground B (Fig. 4 O), and the crushed stone piles D are constructed at predetermined intervals. As a result, ground B will be treated against liquefaction.

When the casing 1 is pulled out, the casing 1 and the drilling rod 2 are reversely rotated for drilling. When the excavator is pulled out, the crushed stone C moves upward, but the crushed stone movement is canceled by the next filling and compacting operation. If the case sink 1 is pulled out by rotating in the excavation direction, the excavation spiral projection 15 becomes a reverse spiral and acts as a resistance, but it is the ground and the hole wall is held by the hole wall pressing portion 16, so that it is particularly troublesome. should not.

1 Casing 11 Cylindrical Part 12 Crushed Stone Input Port 13 Drive Connection Part 14 Excavation Blade 15 Excavation Spiral Projection 16 Hole Wall Pressing Part 17 Inverted T-shaped Groove 2 Excavation Rod 21 Shaft 22 Excavation Part 221 Excavation Shaft 222 Spiral Blade 223 Excavation bit 23 upper end connecting shaft 3 connecting body 31 connecting cylindrical body 311 main body 312 connecting protrusion 313 upper lid 314 connection receiving portion 315 pin mounting hole 32 transmission shaft 321 shaft 322 mounting portion 323 rod connecting portions 324a, 324b, 324c Connecting arm 325 Pin through hole A Excavator a Leader mast b Rotary drive mechanism B Sand C Crushed stone D Drain hole (crushed stone pile)
E borehole

Claims (7)

A casing provided with crushed stone inlets at appropriate intervals in the vertical direction, an excavating rod provided inside the casing and provided with an excavating bit at the lower end and an excavating portion provided with a spiral blade that holds down just above the excavating bit, and is detachably attached to the upper end of the casing. In addition, the excavator is mounted on a predetermined excavator body, and the casing is pushed into the ground by excavation without soil discharge by the excavator, and the casing is put into crushed stone. A ground improvement method in which the excavator is pulled out while the crushed stone is injected from the mouth and the crushed stone is packed and compressed by the excavation part in stages according to the withdrawal of the casing, and crushed stone piles are constructed on the ground. Filling and compression of the crushed stone by the excavation unit is performed by releasing the connection between the connecting body and the casing and pushing crushed stone by rotating the spiral blade of the excavating unit, or pushing crushed stone by vertical movement of the excavating unit, or both. The ground improvement method according to claim 1. Consists of a casing, a drilling rod inside the casing, and a linking body separately connected to the drilling rod and the casing at the upper end of the casing,
The casing comprises a cylindrical portion of a predetermined length provided with crushed stone inlets at suitable intervals in the vertical direction, and a cylindrical driving connection portion that is detachably connected to the connecting body is provided at the upper end of the cylindrical portion,
The drilling rod has, at the lower end of a shaft portion having a predetermined axial length corresponding to the casing, a drilling portion provided with a drilling bit and a spiral blade that holds down directly above the drilling bit and is provided so as to protrude from the tip of the casing by a predetermined length, An upper end connecting portion that connects with the connecting body is provided at the upper end of the shaft,
The linking body includes a linking cylinder fitted detachably to the cylindrical drive connecting part at the upper end of the casing, a mounting part at the upper end to be attached to the excavator body, and a rod connecting part at the lower end. A ground improvement excavator characterized by comprising a transmission shaft body connected in a penetrating manner to and having a structure in which a connection portion between the transmission shaft body and the connecting cylinder body can be vertically changed. 4. The excavating apparatus for ground improvement according to claim 3, wherein the transmission shaft is provided with a plurality of connecting portions which are vertically multi-staged. A connecting portion of the connecting body between the transmission shaft and the connecting cylindrical body is set so that the excavated portion connected to the transmission shaft protrudes from the lower end of the casing and is incorporated, and the position is set in the casing. 5. The ground improvement excavator according to 3 or 4. 6. The drilling apparatus for ground improvement according to any one of claims 3 to 5, wherein the drive connecting portion between the connecting cylinder and the casing is structured such that the casing and the connecting cylinder are disconnected only at a predetermined relative angular position. 7. The excavating apparatus for ground improvement according to any one of claims 3 to 6, wherein a hole wall pressing portion having a pressing inclined surface corresponding to the rotating direction of excavation is provided at an appropriate location on the outer peripheral surface of the casing.

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