JP2006016756A - Extraction method for existing pile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an extraction method for an existing pile capable of easily drawing the existing pile with a small extracting operation force. <P>SOLUTION: A cylindrical casing 3 having a diameter larger than the maximum diameter of the existing pile 6 is driven to at least the depth of the existing pile 6 so as to surround the existing pile 6 while making muddy and sandy a sediment around the lower end inside and outside of the casing 3 with a muddy and sandy agent. Next, the existing pile 6 is drawn while feeding air into a negative pressure space S produced between the lower end of the existing pile 6 and an underground when the existing pile 6 is grasped and drawn together with the casing 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for pulling an existing pile buried in the ground.

  As a method for drawing an existing pile, for example, a cylindrical casing larger than the maximum outer diameter of the existing pile is used, and the existing pile is used while mudizing the sand around the inside and outside of the lower end of the casing with a mudizing agent such as water or bentonite. There is a method in which at least the depth of the existing pile is driven so as to surround, and then the existing pile is grasped and pulled out together with the casing (see, for example, Patent Documents 1 and 2).

Japanese Patent Publication No. 3-57247 JP 2000-154541 A

  However, in the above-mentioned existing pile pulling method, a negative pressure (negative pressure) space is created between the lower end of the existing pile and the ground when the existing pile is pulled out. A very large pulling operation force was required, making the pulling operation difficult. In the worst case, the existing piles to be pulled out may be torn off in the worst case because the existing piles have been buried in the ground for a long time and the tensile strength has greatly decreased due to corrosion. there were.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a method for pulling an existing pile that can be easily and quickly pulled out with a small pulling operation force. It is in.

  In order to achieve the above object, the method of pulling out an existing pile of the present invention is a cylindrical casing larger than the maximum outer diameter of the existing pile, while mudizing the sand around the inside and outside of the lower end of the casing with a mudizing agent, Drive in at least the depth of the existing pile so as to surround the existing pile, and then feed air into the negative pressure space generated between the lower end of the existing pile and the ground when the existing pile is grasped and pulled out together with the casing However, it is characterized by pulling out the existing pile.

  In this case, a fluid transport hose with a nozzle attached to the tip is attached to the casing, and the fluid transport hose can be used both for feeding the muddy agent and for feeding the air.

  When extracting existing piles, air is sent to the space created between the lower end of the existing piles and the ground, so that the negative pressure in the space created by the existing piles can be reduced. It can be done easily and quickly with the operating force and without fear of tearing along the way.

  By using the fluid transport hose as both a mudizing agent and air, simplification of ancillary equipment to the casing and cost reduction can be achieved.

An embodiment of an existing pile drawing method according to the present invention will be described with reference to the drawings.
In FIG. 1, the drawing device used in the existing pile drawing method uses a ground auger in the illustrated example as the driving machine 1, and a casing 3 whose upper end is detachably connected to the auger shaft 2, and the casing 3 includes a plurality of chuck claws 4 attached to the lower end side of the cylinder 3 and a hydraulic cylinder 5 attached to the upper part of the casing 3 for operating the chuck claws 4.

  The casing 3 is formed in a cylindrical shape made of a steel pipe or the like having an inner diameter larger than the maximum outer diameter of the existing pile 6, and a drilling blade 7 is attached to the lower end.

  As shown in FIGS. 4 and 5, the chuck claw 4 is formed of a steel material or the like in a circular shape with a circular arc edge 4 a and a straight edge 4 b, which is tapered and has a circular rear end, and has an arc-shaped cam groove 8. This chuck claw 4 is inserted into the shaft 11 laid between the bearings 10, 10 fixed outside the opening 9 provided on the lower end side of the casing 3, thereby inserting the cam groove 8 into the opening 9 of the casing 3. Advancing and retreating in the vertical direction about the shaft 11 over a retracting posture (see FIG. 5) that extends substantially vertically above the outside and a protruding posture (see FIG. 6) that protrudes substantially horizontally from the opening 9 into the casing 3 Can be installed freely.

  As shown in FIGS. 2 and 3, the hydraulic cylinder 5 has an upper end that is pivotally attached to a support protrusion 12 projecting from the upper outer side of the casing 3, and a telescopic cylinder that protrudes from the lower end of the hydraulic cylinder 5. A lower end portion of the rod 13 and a joint 14 pivotally connected to the rear end portion of the chuck claw 4 are connected by a connecting rod 15 (see FIGS. 4 and 5). The lower end portion of the cylinder rod 13 and the upper end portion of the connecting rod 15 are connected by a pivot 16 so that the expansion and contraction of the hydraulic cylinder 5 can be performed in the vertical direction, while the vertical groove 17 straight in the vertical direction is formed in the casing 3. A pair of guides 18 and 18 are fixed, and both ends of the pivot 16 are slidably fitted in the longitudinal grooves 17 and 17 so that the cylinder rod 13 is regulated to move up and down straight in the vertical direction. Yes. The connecting rod 15 is inserted through a guide 23 fixed to the casing 3 so as to be movable up and down. At that time, when the cylinder rod 13 of the hydraulic cylinder 5 is contracted, the chuck pawl 4 is pulled upward by the connecting rod 13 and retracts out of the casing 3 from the opening 9 in a substantially vertical position (see FIG. 5). Is extended, the chuck claw 4 is pushed down by the connecting rod 13 and protrudes from the opening 9 into the casing 3 in a substantially horizontal posture (see FIG. 6).

  As shown in FIG. 1, the casing 3 is further provided with a fluid transport hose 19 which is used for feeding a mudizing agent such as water or bentonite and for feeding air in a vertical direction. A nozzle 19 a is attached to the tip of the hose 19, and this nozzle 19 a faces an opening 20 provided between adjacent chuck claws 4, 4 at the lower end of the casing 3.

  Next, the pulling method of the existing pile of this invention is demonstrated. First, the upper surface of the existing pile 6 is exposed by excavating the ground surface G near the upper end of the existing pile 6 buried in the ground with a backhoe or the like, and the position thereof is confirmed. Incidentally, the existing pile 6 shown in FIG.1 and FIG.6 is a pedestal pile in which the columnar body 6a, the bulb 6b, and the point 6c are not integrated.

  Thus, the casing 3 is driven into the existing pile 6 with the driving machine 1 as shown in FIG. The casing 3 is rotationally driven by a driving machine 1 made of an earth auger, and is driven into the soil so as to surround the existing pile 6 while being excavated by the excavating blade 7. At this time, a mudizing agent such as water or bentonite is passed through the fluid transport hose 19 and sent to the lower end of the casing 3, and ejected from the nozzle 19 a at the tip of the fluid transport hose 19, and the earth and sand around the inside and outside of the lower end of the casing 3. By muddying the casing 3, the casing 3 reduces the frictional resistance with the earth and sand, so that it can be driven easily. The casing 3 is driven to the depth of at least the existing pile 6, and is preferably driven to a depth at which the lower end of the casing 3 reaches about 1 m below the lower end of the existing pile 6.

  After the casing 3 is driven, the hydraulic cylinder 5 is extended as shown in FIG. 2B, and the chuck claw 4 is protruded into the casing 3 via the connecting rod 15 as shown in FIG. At this time, whether or not the chuck claw 4 has sufficiently protruded into the casing 3 can be confirmed by directly viewing the extension length of the rod 13 of the hydraulic cylinder 5 on the ground. After the chuck claw 4 is completely projected, when a pulling force is applied to the casing 3 by the driving machine 1, the chuck claw 4 is lifted to the existing pile 6 by the chuck claw 4 contacting the lowermost end of the existing pile 6 as shown in FIG. The casing 3 can be pulled out together with the existing pile 6 and the earth and sand M in the casing 3 by applying a force.

  At the time of this extraction, the sending of the mudizing agent to the fluid transport hose 19 is stopped, air or compressed air is sent to the fluid transport hose 19, and this air is drawn between the lower end of the existing pile 6 and the ground. Continue to feed into the space S. As a result, the negative pressure in the space S generated in the extraction trace of the existing pile 6 can be reduced, so that the extraction of the existing pile 6 can be easily performed with a small extraction operation force, and the existing pile 6 is reliably extracted without fear of tearing off halfway. be able to.

The underground hollow part (pile hole) that can be traced out of the existing pile 6 that is pulled out while sending air into the space S generated between the lower end of the existing pile 6 and the ground is reduced by reducing the negative pressure. Collapse of the inner wall of the middle hollow part (pile hole) is less, and the inner wall of the underground hollow part (pile hole) is not softened as in the case of injecting water, so it is close to the depth of the existing pile 6 It is possible to reliably obtain a pile hole that keeps the depth and enables the amount of landfill soil to enter as much as possible in a state where the shape of the pothole is maintained without collapse.
Therefore, in the next pile hole backfilling process, where the existing pile 6 has been pulled out, sludge waste generated by excavation such as new pile driving at other locations on the same site is carried by a backhoe. At this time, the pile hole made after the existing pile 6 has been pulled out is maintained at a depth close to the depth of the existing pile 6 as described above, and the landfill is in a state where the shape of the pothole is maintained without collapse. Since the input capacity is as large as possible, a large amount of sludge waste can be landfilled. For this reason, the processing work which discards the said sludge waste to another place with a dump truck etc. can be labor-saving.

  In addition, according to the chuck | zipper mechanism by the some chuck | zipper claw 4 of the said structure, the middle of the existing pile 6 can be grabbed strongly. Therefore, when it is not necessary to pull out all of the existing piles 6 and only the columnar body 6a of the existing piles 6 is pulled out, it is also possible to pull out by holding the middle of the columnar body 6a. However, even during this extraction operation, the extraction is performed while air is sent into the space S generated between the lower end of the pillar body 6a of the existing pile 6 to be extracted and the ground. In addition, when the length of the existing pile 6 is unknown, as shown in FIG. 7, the pulling operation may be carried out while checking the length of the existing pile 6 by sequentially driving deeply while applying the chuck claws 4 to the existing pile 6. it can.

  In the said Example, although the earth auger was used as the drawing machine 1, it can replace with this and can also use a vibro hammer. In this case, the upper end of the casing 3 is detachably connected to the lower end of the vibro hammer. Existing piles are not limited to pedestal piles, but can also be applied to pulling out, for example, large-diameter cast-in-place concrete piles, steel pipe piles, and expanded piles.

  Further, in the above embodiment, the existing pile 6 is grasped and pulled out by the chuck claw 4 attached to the lower end side of the casing 3, but it is not limited to this drawing method. The existing pile 6 can be pulled out at the same time as the casing 3 is pulled up by the driving machine 1 by setting a wire rope on the upper end portion of the wire 6 and tightening it to wind up the wire rope.

  By using the fluid transport hose for both the mudizing agent and the air, it is advantageous to simplify the incidental equipment to the casing and reduce the cost. Instead, as the fluid transport hose 19, The casing 3 can be provided with a hose dedicated to feeding the muddy agent and a hose dedicated to air feeding.

It is a front view shown in the state where the extraction device of the existing pile was driven into the ground. (A) is a front view which shows the hydraulic cylinder attached to the casing of the drawing apparatus in a contracted state, (B) is a front view which shows the hydraulic cylinder in an extended state. It is C arrow line view in FIG. It is a front view which shows the chuck | zipper nail | claw attached to the casing of the extraction apparatus in the withdrawal state. It is a side view which shows the chuck | zipper nail | claw attached to the casing of the extraction apparatus in the withdrawal state. It is a vertical side view which shows the extraction process of the existing pile in the state which the chuck | zipper claw attached to the casing of the extraction apparatus protrudes. It is explanatory drawing which shows the example of the aspect of the driving | running | working process of a drawing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Driving machine 3 Casing 6 Existing pile 19 Fluid transport hose 19a Nozzle S Negative pressure space

Claims (2)

  A cylindrical casing larger than the maximum outer diameter of the existing pile is driven into at least the depth of the existing pile so as to surround the existing pile while muddying the sand around the inside and outside of the lower end of the casing with a muddying agent, A method for extracting an existing pile, wherein the existing pile is pulled out while air is fed into a negative pressure space generated between a lower end of the existing pile and the ground when the existing pile is grasped and pulled out together with the casing. . The pulling method of the existing pile according to claim 1, wherein a fluid transport hose with a nozzle attached to the tip is attached to the casing, and the fluid transport hose is used both for feeding the mudizing agent and for feeding the air.

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