JP2013122113A - Earth auger for ground improvement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an earth auger for a ground improvement method, capable of forming a waterproof block and at the same time forming an underground pile during a series of steps, and high in work efficiency.SOLUTION: An earth auger for a ground improvement method has a drive top suspended and supported on a rotary arm of a vehicle, etc. at a top end of a center shaft, is formed by combining an auger body with a screw formed at its lower end part and a cylindrical casing with a spiral strip of a size which makes the screw fit thereto in a manner to be mutually and vertically movable, and incorporates a lock device which stops rotation between the center shaft of the auger body and the casing mutually in a gradual position limited manner. An inner spire and an outer spire are provided at a lower end of the center shaft and at a lower end of the casing, respectively, to be a form of screwing front end. Among them, the outer spire is a hollow reverse-cone-shape into which the inner spire is put, a plurality of on-off valves assembling the outer spire are journaled at the lower end of the casing such that the outer spire can be split into two pieces and opened. The outer spire is provided with holding means for preventing the outer spire from opening during screwing, while it is configured such that the inner spire pierces and opens the outer spire by the center shaft lowering with respect to the casing.

Description

  The present invention relates to an earth auger that is used to construct an underground pile by screwing it into the ground as a foundation work for improving soft ground. More specifically, the present invention relates to an earth auger in which a cylindrical screwable casing is combined with a middle shaft having a screw.

  As a method of improving soft ground and liquefied ground, vertical holes for piles are drilled vertically by an earth auger, and cement piles are mixed with excavated soil and backfilled into the vertical holes to create underground piles in the vertical holes. . In this case, the cement-mixed soil buried in the vertical holes is hardened by absorbing water from the surrounding ground to obtain the strength of the underground pile. However, especially in ground with high groundwater, there is a problem that groundwater flows up from the lower end of the vertical hole, and the cement pile is diluted to cause unhardened nests in the underground pile.

  In this applicant, in order to solve this problem, a construction method was proposed in which a water blocking block was formed at the lower end of the vertical hole, and cement mixed soil was filled thereon (Japanese Patent Application No. 2011-184436). . And as a material of a water stop block, it decided to obtain hardening rate by mixing water glass other than mixing base materials, such as sand, and cement.

  This invention is providing the earth auger for the ground improvement construction methods which can implement said ground improvement construction method efficiently. That is, an object of the present invention is to provide an earth auger for ground improvement method with high work efficiency capable of forming a waterproof block and forming an underground pile during a series of steps.

  In order to solve the above-described problems, the present invention has an auger body having a drive top supported by being suspended by a turning arm of a vehicle or the like at the upper end of a middle shaft, and a screw formed at the lower end, and the screw is fitted. For a ground improvement method, a casing with a cylindrical shape with a spiral line is assembled so that it can be moved up and down, and a locking device is installed between the central shaft of the auger body and the casing to stop rotation in a stepwise manner. In the earth auger, the inner cusp is provided at the lower end of the center shaft, and the outer cusp is provided at the lower end of the casing in the form of a screwed tip. Of these, the outer cusp is a hollow inverted conical shape into which the inner cusp enters. A plurality of on-off valves for assembling the shaft are pivotally supported at the lower end of the casing so that they can be opened at least in half, and holding means are provided so as not to open during screwing, In which the inner cusp by the center pole is lowered to provide auger for ground improvement method, characterized by being configured to open butted an outer cusp against pacing.

  Since the earth auger for ground improvement method is constructed as described above, when using it, the casing is screwed to a predetermined depth by rotating it integrally with the center shaft while suspended on a swivel arm such as a backhoe. Then, it is lifted by the height of the waterproof block by reverse rotation, and the molding space of the waterproof block is opened under the retreat.

  Next, materials such as sand, cement, and water glass are added from the upper end of the casing, received by the outer peak at the lower end, stirred with a screw, and then the outer peak at the inner peak at the tip with the center axis lowered. The material is dropped into the molding space, and further agitated with the reversal of the screw projecting there, and pulled up while uniformly filling the material. Thus, the water stop block is hardened and made early by the reaction between cement and water glass in the molding space.

  Now, uncured soil mixed with sand and cement is poured from the top of the casing, and the whole is pulled up while densely filling the uncured soil by reversing the screw. This forms an uncured underground pile that is waterproofed with a water blocking block.

  As explained above, according to the ground auger for the ground improvement method of the present invention, during the construction of the vertical hole, a molding space for forming a waterproof block is provided at the lower end of the vertical hole, and materials such as sand, cement, water glass are provided there. By mixing and filling, it is possible to form a predetermined waterproof block and fill the underground pile material during retreat, so that the underground pile construction work of the ground improvement construction method can be done efficiently at once There is an effect.

It is sectional drawing which shows the earth auger for the ground improvement construction method of this invention at the first screwing process. It is a lower end enlarged sectional view showing the earth auger in the next process. Furthermore, it is sectional drawing shown at the following process. Furthermore, it is a lower end part sectional drawing shown at the next process. It is an expanded sectional view of the lower end part explaining the part (protection cover) omitted in each figure. It is sectional drawing which shows the same part in the state which opened the outer cusp. It is sectional drawing which shows the underground pile which has a still water block created with the earth auger.

  The drawing shows an embodiment, and an earth auger for the ground improvement method is composed of a combination of an auger body 1 that is directly suspended from a turning arm of a work vehicle and a cylindrical casing 3 into which the screw 9 is fitted. Thus, the auger body 1 is suspended and supported on the turning arm of the work vehicle, and the vertical hole 4 is drilled by screwing the outer casing 3 (the leading hole may be drilled in advance). This vertical hole 4 is the depth which match | combined the part Hb of the underground pile 29, and the part Ha of the water stop block 25 (FIG. 1, FIG. 7).

  The auger body 1 has a screw 9 formed at the lower end portion of the central shaft 6 as a center, and a driving top 5 that is directly attached to the swivel arm is provided at the upper end, and an inverted conical sharp inner peak 11 is provided at the lower end. It is done. In the lower part of the middle shaft 6, the screw 9 is formed in a size that fits into the casing 3, reaches the lower end of the inner cusp 11 and tapers there.

  The casing 3 has a cylindrical shape through which materials such as sand, cement, water glass and the like can pass, and a hopper 13 serving as a material receiver is provided at the upper end in a reverse shade shape, and the inner peak 11 is accommodated at the lower end. A hollow, inverted conical outer peak 15 is provided that can be opened and closed. Moreover, the spiral strip 17 is formed in the outer periphery of the lower end part of the casing 3 by rotating and arranging a reinforcing bar.

  The outer cusp 15 is composed of a pair of on-off valves 27 and 27 (FIG. 2) having an inverted conical shape, and the support shafts 28 and 28 are provided at the lower end of the casing 3. Further, two sharp projections 31 are also formed at the tip, and both of the split pieces 32 and 32 are fastened together by a wire (number wire) 33. Moreover, the groove | channel 35 (FIG. 6) where the wire 33 hooks is formed in the split pieces 32 and 32. As shown in FIG. The support shafts 28, 28 of the on-off valves 27, 27 are covered with a protective cover 37, which will be described later in FIG. 5 and FIG.

  The drive top 5 is internally provided with a drive device that rotates the middle shaft 6 forward and backward by hydraulic pressure. The screw 9 and the spiral strip 17 are shaped to be propelled in the clockwise forward rotation. Note that the casing 3 is rotated integrally with the middle shaft 6 during propulsion. For this reason, a locking device is provided (not shown) so that it rotates integrally with the lower portion of the casing 3 where the hopper 13 is separated (W) from the drive top 5, and there are other locking devices. 6 and the casing 3 are partially provided with projecting pieces that are hooked to each other.

  Next, usage will be described, and the sequential structure will be specifically described. In this case, the vertical hole 4 is drilled in the ground G that is close to groundwater and is soft, and the waterproof block 25 (Ha portion) solidified with sand, cement, water glass or the like is formed at the lower end of the vertical hole 4. Then, it is a series of steps of filling uncured soil (in the Hb portion) mixed with the return sand and cement (FIGS. 1 and 7).

  First, the locking device is closed, the casing 3 is rotated forward together with the middle shaft 6, and the vertical protrusion 4 is formed on the soft ground G with the sharp protrusion 31 facing first, so that the vertical hole 4 is formed (FIG. 1).

  Next, the casing 3 is reversely rotated together with the center shaft 6, and the earth auger is lifted by about 50 cm together with the operation of the arm of the shovel car (FIG. 2). Then, after retreating, a molding space 34 is created at the lower end of the vertical hole 4.

  When a waterproof block material such as sand, cement or water glass is introduced from the hopper 13, it is collected at the lower end portion of the casing 3 by the receptacle of the outer cusp 15 (part K). In this case, in order to make the material uniform, the material is pushed in the direction of the outer peak 15 by the reverse rotation of the screw 9.

  Next, when only the auger body 1 is lowered with respect to the casing 3 while lowering the arm, the wire 33 is cut by the force, and the outer cusp 15 is split in two (FIG. 3). As a result, the material fed into the lower end of the auger body 1 is fed into the deep portion together with the screw 9, where the material is uniformly mixed by the reverse stirring action of the screw 9 (FIG. 4). so). Then, since it hardens quickly due to the reaction between the cement and the water glass, the whole is pulled up before that, while the improved soil mixed with sand and lime is put in from the hopper 13 and the pulling is continued in the same manner as shown in FIG. The uncured underground pile 29 on the waterproof block 25 is densely formed with the reversal of 9.

  Support shafts 28, 28 of the on-off valves 27, 27 are provided at the lower end of the casing 3. As shown in FIGS. 5 and 6, a protective cover made of an elastic material is used to prevent clogging with earth and sand. 37, 37 are coated. The protective cover 37 is formed with an inclination along the spiral direction of the spiral strip 17, and an upper end portion 37 a and a lower end portion 37 b are tapered. Further, it is configured so as to be separated in conformity with the opening and closing of the outer peak 15. Further, protective covers 37 and 37 and both open / close valves 27 and 27 are attached to the open / close arms 30 and 30 of the support shafts 28 and 28, and the open / close valves 27 and 27 are biased in the opening direction via the protective covers 37 and 37. Yes. If the on-off valves 27 and 27 are naturally closed, there is a possibility that the gap between the water blocking block 25 and the uncured underground pile 29 may be broken, which is prevented.

DESCRIPTION OF SYMBOLS 1 Auger main body 3 Casing 5 Driving top 6 Center shaft 9 Screw 11 Inner cusp 15 Outer cusp 17 Spiral strip 27 On-off valve 28 Support shaft 31 Sharp protrusion 32 Split piece 33 Wire (holding means)
35 Groove 37 Protective cover

Claims (3)

  An auger body having a drive top suspended and supported on a turning arm of a vehicle or the like at the upper end of the middle shaft, and a casing having a cylindrical shape and a spiral line to which the screw fits, and a screw formed at the lower end portion In the earth auger for ground improvement method, which is assembled with a lock device that stops rotation between the central shaft of the auger body and the casing in a stepwise position, the inner cusp is attached to the lower end of the central shaft. The outer cusp is provided at the lower end of each in a shape that becomes the tip of the screwing, of which the outer cusp is a hollow inverted conical shape into which the inner cusp enters and can be opened at least in half. A plurality of on-off valves that assemble it are pivotally supported at the lower end of the casing, and are provided with holding means so as not to open during screwing, while the central shaft is lowered with respect to the casing. Auger for ground improvement method, wherein the inner cusp is configured to open butt outer cusp.   A sharp projection is provided at the lower end of the outer cusp, and the sharp projection comprises a set of split pieces protruding from the tip of each on-off valve, and each of the split pieces is formed with an engagement groove that is bound by a wire. 2. An earth auger for ground improvement according to claim 1, further comprising holding means. A support shaft that supports the open / close valve in an openable / closable manner is provided at the lower end of the casing, and a protective cover that covers the support shaft is provided over both the casing and the outer cusp. An earth auger for ground improvement according to claim 1 or 2, wherein the ground auger is used.

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