JP2013112937A - Press-in pile method with unsaturation function, and construction device used for the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a press-in pile method with an unsaturation function that is applicable to a narrow construction condition, environmentally friendly, and economical.SOLUTION: In the press-in pile method of making a press-in pile 9 by forming a drilled part 3 by excavating the natural ground 1b by an excavation diameter expansion device 30 and an auger screw 20 up to a predetermined depth H of the ground 1 and removing the earth to a ground surface 1a, and tempering water-permeable granular material 8 and expanding the diameter by repeatedly extracting and driving in the excavation diameter expansion device 30 and auger screw 20 while throwing the water-permeable granular material 8 in the excavated part 3 when pulling out the excavation diameter expansion device 30 and auger screw 20 from the excavated part 3, the interior of the excavated part 3 is closed with an air leakage preventive valve 34 provided to the excavation diameter expansion device 30 and the natural ground 1b at a periphery of the excavated part 3 is made unsaturated by discharging air from an air discharge hole 36 provided to the excavation diameter expansion device 30 and injecting the air into the natural ground 1b when the press-in pile 9 is made.

Description

  In the present invention, crushed stones and sand are compacted and expanded to form a press-fit granular pile (hereinafter simply referred to as “press-fit pile”), the ground around the press-fit pile is compacted, and excess gaps that cause liquefaction The present invention relates to a press-in pile method with a desaturation function used in a liquefaction countermeasure method that dissipates water pressure and desaturates the surrounding ground of a press-in pile, and a construction device used in the method.

  One of the liquefaction countermeasure methods is known as a crushed stone drain method. In this crushed stone drain method, a hole is drilled to a predetermined depth in sandy ground where liquefaction occurs due to an earthquake, and crushed stone is put into the hole to construct a crushed stone pile in the ground. This is a method of preventing liquefaction by suppressing and dissipating excess pore water pressure.

JP-A 61-207711

  In the conventional crushed stone drain method, it is a drain pile that dissipates excess pore water pressure of the ground to be liquefied, and since there is little ground displacement at the time of construction, it may be cheap, but as the earthquake level increases, the drain pile Since it is necessary to narrow the pitch interval, there is a problem that the construction cost is increased accordingly. In addition, the construction machinery is large, and it was difficult to construct on narrow land or land adjacent to existing structures.

  Therefore, the present invention has been made to solve the above-mentioned problems. By constructing a press-fitted pile with a desaturation function using a small construction machine, the scope of application to the earthquake level is improved, and a press-fitted pile construction method and Providing composite technology of saturation method by effective construction method, it can be applied to narrow construction conditions, and it is an environmentally friendly economical press-in pile method with desaturation function and excavation used for this method An object is to provide a diameter expanding device.

  The invention of claim 1 uses a construction device equipped with a drilling and expanding device at the tip of an auger screw integrally coupled with a forced lifting device capable of obtaining a reaction force from a supporting leader, and up to a predetermined depth of the ground. A drilling part is formed by excavating the original ground with the construction device and discharging it to the ground surface. When the construction device is pulled out from the drilling part, a permeable granular material is introduced into the drilling part. In the press-in pile method with the desaturation function, the above-mentioned press-in pile is formed by repeating drawing, re-penetration using the construction device, and compacting and expanding the water-permeable granular material to form a compacted press-in pile. When forming, the inside of the hole is closed with an air leakage prevention valve built in the drilling diameter expanding device, and air is discharged from an air discharge port provided in the drilling diameter expanding device to surround the hole The air is injected into the ground of the soil and desaturated. That.

  The invention according to claim 2 is the press-fitting pile method with desaturation function according to claim 1, which is provided at the tip of the auger screw, and is open at the time of forward rotation and closed at the time of reverse rotation. The digging and expanding apparatus constituted by a valve and an air discharge port is used to discharge the air from the air discharge port during the re-penetration.

  The invention of claim 3 uses a construction device equipped with a drilling and expanding device at the tip of an auger screw integrally coupled with a forced lifting device capable of obtaining a reaction force from a supporting leader, and up to a predetermined depth of the ground. A drilling part is formed by excavating the original ground with the construction device and discharging it to the ground surface. When the construction device is pulled out from the drilling part, a permeable granular material is introduced into the drilling part. In the construction apparatus used for the press-in pile method for forming the compacted press-fit pile by compacting and expanding the water-permeable granular material by repeating drawing and re-penetration using the construction equipment, a cylindrical auger screw A cylindrical excavation and enlargement device attached to the outside of the lower end side opening of the cylindrical excavator, and an opening of the cylindrical excavation and enlargement device attached to the attachment member via a hinge so as to be rotatable. An air leak prevention valve that opens and closes Wherein mounted on the mounting member, characterized by comprising an air discharge port for injecting ejecting air into original ground around the drilling unit when the reclamation the press-pile.

  Invention of Claim 4 is the construction apparatus of Claim 3, Comprising: The planar view according to the number of the said air leak prevention valves by making the said attachment member into the lower end side opening part of the said cylindrical excavation diameter expanding apparatus Attaching, the air leakage prevention valve is attached to the outer peripheral side of the mounting member in a uniform shape in a plan view from the center position of the mounting member in a plan view through a hinge, and the center of the mounting member in a uniform shape in the plan view The air discharge port is attached at a position.

  As explained above, according to the press-fit pile method with the desaturation function of the invention of claim 1, the press-fit pile method with the desaturation function that combines the press-fit pile method with the desaturation method can be provided. In other words, this press-fit pile method with desaturation function uses environmentally friendly materials (materials that have the necessary drainage function such as crushed stone and sand), suppresses displacement to the surrounding ground during construction, Construction on land adjacent to existing structures can be done easily and economically.

  In addition, by combining the press-in pile method with the desaturation function, it is possible to reduce the increase in excess pore water pressure with the desaturation function even at earthquake levels that are not compatible with the press-in pile method, and to broaden the application range. Can do.

  Furthermore, the desaturation function can be provided at the same construction cost as that of the conventional crushed stone drain construction method, and construction can be performed with the same construction efficiency as that of the conventional crushed stone drain construction method.

  According to the press-fitting pile method with the desaturation function of the invention of claim 2, since the air is discharged from the air discharge port when the digging diameter expanding device is driven back, it tends to escape from the drilled portion to the ground surface. Air can be reliably injected into the original ground around the drilled portion, and the original ground around the drilled portion can be efficiently and reliably desaturated.

  According to the construction apparatus of the invention of claim 3, the desaturation function that enables the air injection into the ground is provided by equipping the digging and expanding apparatus used for the press-fitting method with the air leakage prevention valve and the air discharge port. It can be combined, and the construction of press-fit piles and the desaturation of the ground can be performed simultaneously. In addition, the press-fitting formation part consisting of multiple press-fitting piles is constructed after discharging the original ground soil to the ground surface with a digging diameter expansion device and an auger screw, so that environment-friendly construction with suppressed ground displacement during construction is performed. be able to.

  According to the construction apparatus of the fourth aspect of the present invention, the mounting member is attached to the lower end side opening of the cylindrical excavating and expanding apparatus according to the number of the air leakage prevention valves evenly in plan view. By attaching the air leakage prevention valve to the outer peripheral side from the center position of the flat plate in a uniform shape in plan view through a hinge, and attaching the air discharge port to the center position of the mounting member in a uniform shape in plan view, It is possible to reliably prevent air leakage from coming out from the drilled portion to the ground surface. Thereby, air can be efficiently and reliably injected into the original ground around the drilled hole, and the original ground around the drilled hole can be efficiently and reliably desaturated.

It is a side view of the construction apparatus used for the press-fit pile method with a desaturation function of one embodiment of the present invention. (A) is a side view at the time of penetration of the digging diameter expansion device of the construction apparatus, (b) is a bottom view of the digging diameter expansion device at the time of penetration, (c) is a perspective view of the digging diameter expansion device at the time of penetration. It is. (A) is the side view at the time of extraction of the said excavation diameter expansion apparatus, (b) is a bottom view of the excavation diameter expansion apparatus at the time of the said extraction, (c) is a perspective view of the excavation diameter expansion apparatus at the time of the said extraction. (A) is a side view of the digging diameter expansion device at the time of returning, (b) is a bottom view of the digging diameter expansion device at the time of returning, and (c) is a perspective view of the digging diameter expansion device at the time of returning. It is. It is explanatory drawing which shows in order the process of constructing by the said press-fit pile method with a desaturation function. It is explanatory drawing which shows construction of the said press-fit pile method with a desaturation function. (A) is a top view of the press-fit pile created by the construction of the press-fit pile method with the desaturation function, and (b) is a cross-sectional view of the press-fit pile.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a side view of a construction apparatus used in the press-fitting pile method with a desaturation function according to an embodiment of the present invention, FIG. 2A is a side view of the construction apparatus when the drilling diameter expanding apparatus is inserted, and FIG. b) is a bottom view of the digging diameter expansion device at the time of penetration, FIG. 2 (c) is a perspective view of the digging diameter expansion device at the time of penetration, and FIG. 3 (a) is a side view when the digging diameter expansion device is pulled out. 3 (b) is a bottom view of the digging diameter expanding device at the time of extraction, FIG. 3 (c) is a perspective view of the digging diameter expansion device at the time of extraction, and FIG. 4 (a) is a strike of the digging diameter expansion device. 4B is a bottom view of the digging diameter expanding device at the time of returning, FIG. 4C is a perspective view of the digging diameter expanding device at the time of returning, and FIG. 5 is the unsaturated state. Fig. 6 is an explanatory diagram showing the construction process of the press-fitting pile method with the desaturation function, Fig. 6 is an explanatory diagram showing the construction of the press-fitting pile method with the desaturation function, and Fig. 7 (a) is a press fit with the desaturation function. Plan view of a press-pile which is reclamation by application of method, FIG. 7 (b) is a sectional view of the press-pile.

  As shown in FIG. 1, the construction apparatus 10 has a support leader 12 on the front surface side of the construction apparatus main body 11, and the support leader 12 stands vertically with respect to the ground surface 1 a of the ground 1. Yes. The supporting leader 12 is provided with an auger screw 20 having a drilling diameter expanding device 30 connected to the tip thereof via a forced lifting device 13 so as to be movable up and down and rotatable. That is, the auger screw 20 is integrally coupled with a forced lifting device 13 that can obtain a reaction force from the supporting leader 12, and a drilling diameter expanding device 30 is provided at the tip of the auger screw 20.

  The auger screw 20 is formed in a hollow circular tube (cylindrical shape), and a spiral blade 21 is continuously provided from the center of the outer peripheral surface 20a to the tip (lower end). Then, the drilling portion 3 is formed by excavating the original ground 1b by the rotation and up-and-down movement of the auger screw 20 and the digging and expanding device 30 described later and discharging it to the ground surface 1a. When pulling out the auger screw 20 and the digging and expanding device 30, a water-permeable granular material (a material having a necessary drainage function such as crushed stone and sand) 8 supplied along the hollow circular auger screw 20 is drilled. 3 and at the same time, the auger screw 20 and the digging diameter expanding device 30 are driven back to compact the raw ground 1b around the drilled hole 3 and the water-permeable granular material 8 is compacted and expanded to press-fit piles. 9 is to be created.

  The excavation diameter expanding device 30 includes a cylindrical device main body 31 attached to the outside of a lower end side opening (opening) 20b of a hollow circular auger screw 20 via a cross-shaped mounting rod (mounting member) 32. The air leakage prevention valve is attached to the mounting rod 32 via a hinge 33 so as to be rotatable, and opens and closes the lower end opening 31b of the cylindrical device body 31 and the lower end opening 20b of the hollow circular auger screw 20. 34, and a jet nozzle (air discharge port) 36 that is attached to the mounting rod 32 and discharges and injects compressed air (air) A into the base ground 1b around the drilling portion 3 when the press-fitted pile 9 is formed. It has.

  A pair of excavation claws 35, 35 are projected from opposite positions on the outer peripheral surface of the apparatus main body 31. The cross-shaped mounting rod 32 is fixed to the lower end edge of the lower end side opening 20b by welding or the like so that the center position 32a thereof matches the center position of the lower end side opening 20b of the hollow circular auger screw 20. In addition, the four end portions 32b of the cross-shaped mounting rod 32 are fixed to the inner peripheral edge of the lower end side opening portion 31b of the cylindrical device body 31 by welding or the like. A quarter-disc-shaped (fan-plate) air leakage prevention valve 34 is rotatably attached to each end 32b from the center position 32a of the cross-shaped mounting rod 32 via a hinge 33. A jet nozzle 36 is attached to the center position 32 a of the cross-shaped attachment rod 32. The jet nozzle 36 is connected to the air swivel 14 attached to the upper side of the forced lifting device 13 through a connection pipe (not shown) that passes through the hollow circular auger screw 20.

  According to the construction apparatus 10 described above, the digging and expanding apparatus 30 used for the press-fitting pile construction method is equipped with the air leakage prevention valve 34 and the jet nozzle 36 for air discharge, so that air can be injected into the ground 1. It is possible to combine the desaturation function, and the construction of the press-fit pile 9 and the desaturation of the original ground 1b can be performed simultaneously.

  Further, as shown in FIG. 7, the press-fitting pile forming portion composed of a plurality of press-fitting piles 9 is formed after the soil of the original ground 1 b is discharged (soiled) to the ground surface 1 a by the excavation diameter expanding device 30 and the auger screw 20. By doing so, it is possible to perform environment-friendly construction that suppresses ground displacement during construction.

  Further, a quarter-disc-shaped air leak is formed at each end portion 32b on the outer peripheral side from the center position 32a of the mounting rod 32 attached to the lower end side opening portion 31b of the cylindrical device body 31 of the excavating diameter increasing device 30 in a cross shape. Each of the prevention valves 34 is rotatably attached via a hinge 33, and a jet nozzle 36 for air discharge is attached to the center position 32a of the cross-shaped attachment rod 32. Leakage of the compressed air A that is about to escape can be reliably prevented. Thereby, the compressed air A can be efficiently and reliably injected into the original ground 1b around the drilling portion 3, and the original ground 1b around the drilling portion 3 can be unsaturated efficiently and reliably. it can.

  Next, the construction procedure of the countermeasure against liquefaction by the construction apparatus 10 will be described based on the process diagram of FIG. In this construction apparatus 10, an auger screw 20 having a total length of 10 m and a drilling diameter expanding apparatus 30 having a diameter of 0.4 m are used.

  First, as shown in the state of (1) in FIG. 5, the construction apparatus 10 is installed at a predetermined construction position on the ground 1 such as sandy that causes liquefaction due to an earthquake. Next, as shown in the state of (2) in FIG. 5, the excavation diameter expanding device 30 and the auger screw 20 of the construction device 10 are rotated forward to start penetration.

  Next, as shown in the state of (3) in FIG. 5, excavation is performed to the length of the spiral blade 21 of the auger screw 20 (for example, a depth of 5 m) by forward rotation of the excavating diameter expanding device 30 and the auger screw 20. At this point, the excavating and expanding device 30 and the auger screw 20 are withdrawn by stopping or reversing the rotation, and the original ground 1b on the spiral blade 21 up to the depth (for example, depth 5 m) is discharged to the ground surface 1a.

  Next, as shown in the states of (4) and (5) in FIG. 5, the excavation diameter increasing device 30 and the auger screw 20 are again rotated in the normal direction, and the drilling depth in the state of (3) in FIG. It penetrates deeper and repeats the earth removal by the same construction method as the above (3), penetrates to the design depth (predetermined depth) H (for example, 10 m), and earths the ground surface 1a to finish the drilling. Thereby, the drilling part 3 is formed in the predetermined construction position of the ground 1.

  Next, as shown in the state of (6) in FIG. 5, the excavation diameter increasing device 30 and the auger screw 20 are penetrated to the design depth H by normal rotation. When the digging diameter expanding device 30 is bottomed to the design depth H, the air leakage prevention valve 34 provided in the apparatus main body 31 of the digging diameter expanding device 30 is closed as shown in FIG.

  Next, the digging diameter expanding device 30 and the auger screw 20 are reversed, and the compressed air A is discharged from the jet nozzle 36 provided in the center of the lower end side opening 31b of the apparatus main body 31 of the digging diameter expanding device 30 to compress the compressed air. A discharge is started. The discharged compressed air A is discharged in a position deeper than the depth of the hole 3 blocked by the air leakage prevention valve 34 and in the lateral direction, and the hole 3 is blocked by the air leakage prevention valve 34. Therefore, the compressed air A is injected into the original ground 1b around the drilled portion 3 without the compressed air A getting out to the ground surface 1a, and the original ground 1b around the drilled portion 3 is desaturated. .

  Further, as shown in the state of (7) in FIG. 5, a required amount of water-permeable granular material 8 is introduced into the hopper 15 with a measuring instrument on the ground surface 1a, and the water-permeable granular material 8 is formed into a hollow tubular shape. Along with the auger screw 20, it is put into the hole drilling section 3.

  Next, as shown in the state of (8) of FIG. 5, the excavation diameter expanding device 30 and the auger screw 20 are reversed and the compressed air A is supplied while the excavation diameter expanding device 30 and the auger screw are supplied from the hole portion 3. 20 is pulled out by a predetermined length L1 (for example, 0.5 m). At this time, as shown in FIG. 3, the air leakage prevention valve 34 hangs downward due to its own weight, and the water-permeable granular material 8 introduced along with the hollow circular auger screw 20 has the hollow circular auger screw 20. The lower end side opening portion 20b and the lower end side opening portion 31b of the cylindrical apparatus main body 31 of the excavation diameter increasing device 30 are supplied into the drilling portion 3.

  Subsequently, as shown in the state of (9) in FIG. 5, the excavation diameter expanding device 30 and the auger screw 20 are reversed to supply the compressed air A while the excavation diameter expansion device 30 and the auger screw 20 are reversed. Strike back to L2 (for example, 20 cm, L2 <L1). As shown in FIG. 4, the air leakage prevention valve 34 is closed by this reversal (re-penetration), and the leakage of the supplied compressed air A to the ground surface 1 a is cut off and supplied again to the surrounding ground. And the surrounding ground is desaturated. Further, the back of the excavating diameter expanding device 30 and the auger screw 20 is used to compact the raw ground 1b around the hole-drilling portion 3, thereby increasing the strength of the raw ground 1b.

  Next, as shown in the states of (10) to (12) in FIG. 5, the above cycles (8) and (9) are repeated to obtain a predetermined depth as shown in FIGS. 5 and 7 (b). The press-fit pile 9 is created up to the upper end of H.

  The injection amount of the compressed air A for desaturating the original ground 1b in (7) to (11) in FIG. 5 is calculated by the following equations (1) and (2).

[Formula 1]
^{V = (πD 2/4)} × L
Here, V: Desaturation target volume, D: Desaturation target region diameter, L: Desaturation target depth [Formula 2]
Va = (1−Sr / 100) × e × V / (1 + e)
Here, Va: air injection amount necessary for saturation, Sr: saturation (%), e: gap ratio of original ground Therefore, air injection amount required for saturation of raw ground 1b Va is the amount of air Va injected into the 1 m depth section when the area of 2.0 m in diameter from the axial center of the excavating and expanding apparatus 30 is assumed to have a saturation degree of 90% or less and the original ground clearance ratio e = 1.0. Becomes 160 liters / min or more.

  The above-described press-in pile 9 suppresses the increase in excess pore water pressure during the earthquake by the drain effect, and increases the strength of the original ground 1b by compacting the surrounding ground to suppress the increase in excess pore water pressure. The countermeasure against liquefaction is improved by suppressing the increase of the excess pore water pressure by desaturation.

  Thus, the construction apparatus 10 can provide a press-in pile method with a desaturation function that combines the press-in pile method with the desaturation method. In other words, this press-fit pile method with desaturation function uses environmentally friendly materials (materials that have the necessary drainage function such as crushed stone and sand), and does not cause displacement to the surrounding ground during construction. Construction on narrow land and land adjacent to existing structures can be done easily and economically.

  In addition, by combining the press-in pile method with the desaturation function, it is possible to reduce the increase in excess pore water pressure with the desaturation function even at earthquake levels that are not compatible with the press-in pile method, and to broaden the application range. Can do.

  Furthermore, the desaturation function can be provided at the same construction cost as that of the conventional crushed stone drain construction method, and construction can be performed with the same construction efficiency as that of the conventional crushed stone drain construction method.

  Further, when the digging diameter expansion device 30 and the auger screw 20 are driven back, the lower end side opening 31b of the cylindrical device body 31 of the digging diameter expansion device 30 is closed by the four air leakage prevention valves 34, that is, The compressed air A is discharged from the air discharge jet nozzle 36 downward from the center of the lower end side opening 31b of the apparatus main body 31 in a state where the hole drilling portion 3 is closed by the four air leakage prevention valves 34. As a result, the compressed air A that is about to escape from the hole drilling part 3 to the ground surface 1a can be reliably injected into the original ground 1b around the hole drilling part 3, and the original ground around the hole drilling part 3 1b can be efficiently and reliably unsaturated.

  In addition, according to the said embodiment, although the lower end side opening part of the apparatus main body of a digging diameter expanding apparatus was opened and closed with four air leak prevention valves, two or three air leak prevention valves may be sufficient, Further, although one auger screw is used, a plurality of auger screws may be added and used.

DESCRIPTION OF SYMBOLS 1 Ground 1a Ground surface 1b Original ground 3 Drilling part 8 Permeable granular material 9 Compaction press-fit pile 10 Construction apparatus 12 Leader for support 13 Forced raising / lowering apparatus 20 Auger screw 20b Lower end side opening 30 Drilling diameter expansion apparatus 31b Lower end side Opening (opening)
32 Cross-shaped mounting rod (mounting member)
32a Center position 32b End (outside)
33 Hinge 34 Air leakage prevention valve 36 Jet nozzle (air discharge port)
A Compressed air (air)
H Predetermined depth

Claims (4)

Using the construction device equipped with a drilling diameter expansion device at the tip of the auger screw that is integrated with the forced lifting device that can obtain the reaction force from the leader for support, the original ground is moved to the predetermined depth of the ground by the construction device. Using the construction device, excavating and discharging to the surface of the earth to form a hole, and pulling the construction device out of the hole, while introducing a water-permeable granular material into the hole In the press-in pile method for creating a compacted press-fit pile by compacting and expanding the water-permeable granular material by repeating drawing and re-penetration,
When constructing the press-fitting pile, the drilling hole is closed with an air leakage prevention valve built in the excavation diameter expansion device, and air is discharged from an air discharge port provided in the excavation diameter expansion device. A press-fitting pile method with a desaturation function, wherein the air is injected into the ground around the hole to be unsaturated. It is a press-fit pile construction method with desaturation function according to claim 1,
The excavator diameter increasing device, which is provided at the tip of the auger screw, opens at the time of forward rotation and closes at the time of reverse rotation and is configured by an air discharge port and an air discharge port, and at the time of re-penetration, A press-in pile method with an unsaturated function, wherein the air is discharged from an air discharge port. Using the construction device equipped with a drilling diameter expansion device at the tip of the auger screw that is integrated with the forced lifting device that can obtain the reaction force from the leader for support, the original ground is moved to the predetermined depth of the ground by the construction device. Using the construction device, excavating and discharging to the surface of the earth to form a hole, and pulling the construction device out of the hole, while introducing a water-permeable granular material into the hole In the construction equipment used in the press-in pile method for compacting and expanding the diameter of the water-permeable granular material by repeatedly drawing and re-penetrating to create a compacted press-in pile,
A cylindrical excavating and expanding device attached to the outside of the opening on the lower end side of the cylindrical auger screw via an attachment member, and the cylindrical excavation attached to the attachment member via a hinge so as to be rotatable. An air leakage prevention valve that opens and closes the opening of the diameter expansion device, and an air discharge port that is attached to the mounting member and discharges air into the base ground around the drilling portion when the press-fitting pile is formed. Construction equipment characterized by comprising The construction device according to claim 3,
The mounting member is mounted evenly in plan view in accordance with the number of the air leakage prevention valves in the lower end side opening of the cylindrical excavating and expanding apparatus, and the mounting member is planarly viewed from the center position of the mounting member in plan view. A construction apparatus characterized in that the air leakage prevention valve is mounted in a uniform shape so as to be rotatable through a hinge, and the air discharge port is mounted at the center position of the mounting member having a uniform shape in plan view.

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