JP5523959B2 - Pile hole wall protection method - Google Patents

Description

  The present invention relates to a method for protecting a hole wall of a cast-in-place pile simultaneously with excavation.

  Conventionally, a hole wall protective work has been installed while excavating manually, and then a pile hole is excavated by a machine, but in pile construction in a narrow place close to the track, etc. Hole wall protection is carried out by installing liner plates while drilling manually. In case of soft ground or high groundwater level, chemical injection may be performed. These piles must be constructed in a short time during the night without train operation. In addition, as a hole wall protection method, a cylindrical retaining wall assembly consisting of a cage plate and a skin plate covering the outer periphery of the cage frame is added as a unit element over a plurality of stages, and only the bottom skin plate is added to the cage frame. In the joined state, a method has been proposed in which a cage frame is press-fitted into the ground to a predetermined depth as a load means, and only the skin plate is left as a retaining wall to remove the cage frame (for example, Patent Document 1).

Japanese Patent Laid-Open No. 2006-125055

  In the construction method of Patent Document 1, a large load means for press-fitting the retaining wall is required, and the work becomes large. In addition, press-fitting is performed while swinging a long standpipe, but heavy machinery is required, and in the work between tracks, the construction of the station building is difficult because it is necessary to remove the roof once. There is also a method of press-fitting while welding a short pipe, but it takes time to weld and requires a counterweight to take the reaction force at the time of press-fitting. It was also necessary to take a reaction force from the ground by hitting the ground, and the work became large.

The present invention is intended to solve the above-described problem, and eliminates the need for large-scale equipment for press-fitting a pipe, and enables hole wall protection to be performed in parallel with pile hole excavation of cast-in-place piles in a short time. With the goal.
In parallel with the pile hole excavation work of the cast-in-place pile, the present invention connects a plurality of cylindrical tubes having a smaller diameter than the pile hole and shorter than the depth of the excavated portion or the same length along the hole wall. A pile hole wall protection method in which the gap between the hole wall and the cylindrical tube is filled with a backing material and closely adhered,
Wire tip around a cylindrical tube of the lowermost end, Rutotomoni fitted with a sealing material in contact with the bore wall when darken cylindrical tube to prevent escape of Urakomi material, cylindrical tube of the sealing material at a plurality of places or from the ground, It is characterized by being hung by.
Further, the present invention is characterized in that a leakage preventing material is disposed in the vicinity of the wire attachment location of the escape preventing sealing material.
In addition, the present invention is characterized in that the sealing material is longer than the entire length of each cylindrical tube, and has an end that protrudes to the ground.

  At the same time as excavation, the present invention is to drop a pipe along a hole wall while connecting a plurality of cylindrical pipes having a diameter smaller than the pile diameter and shorter than the depth of the excavated portion or the same length. A sealing material that prevents the escape of the backing material in contact with the bottom wall can be attached to the periphery of the tip of the cylindrical tube at the lowermost end so that the hole wall and the cylindrical tube are in close contact with each other, and the hole wall can be protected simultaneously with the excavation.

It is a figure explaining simultaneous construction of pile hole excavation and hole wall protection. It is a figure explaining a hole wall protection. It is a figure explaining the example of the outflow prevention sealing material of the backing material of a cylindrical pipe lower end part. It is a figure explaining the example which suspended the sealing material with the wire.

Embodiments of the present invention will be described below. In addition, although the example which constructs a cast-in-place pile in the vicinity of station buildings, such as between tracks, is demonstrated below, it cannot be overemphasized that this invention is not limited to a construction place.
FIG. 1 is a diagram for explaining an example of a hole wall protection method when constructing a cast-in-place pile. FIG. 1 (a) is a side sectional view, and FIG. 1 (b) is a top view for explaining an excavator and a liner plate. is there.
When excavating a pile hole in the vicinity of the station platform 3, the temporary enclosure 5 is installed and the excavator ground device 10 is rotated to drive the excavating bit 12 attached to the tip of the rod 11 to excavate the natural ground 1. In this embodiment, simultaneously with excavation, a steel cylindrical tube 14 such as a liner plate having a smaller diameter than the pile hole is dropped along the hole wall 15. The cylindrical tube 14 is not limited to steel, and may be made of, for example, reinforced concrete, concrete, resin, wood, or the like, and may be appropriately selected and used depending on the situation at the site. The cylindrical tube 14 is formed by connecting a plurality of stages of tubes having a length shorter than or equal to the depth of the excavated portion with bolts or the like, suspended by a support jig 13 with wires, and sequentially dropped. At this time, since the cylindrical tube 14 has a smaller diameter than the pile hole, it can be easily dropped by its own weight. In addition, the figure shows an example in which the cylindrical pipes are connected to the bottom of the pile, but if the ground toward the bottom of the pile is hard and firm, the cylindrical pipe is only halfway through the soft pile hole in the ground. You may make it construct.

  A viscous back made of cement milk, cement milk mixed with air, clay mixed with a solidifying material or a solidifying agent, etc. between the cylindrical tube 14 and the hole wall 15 as the cylindrical tube 14 is dropped. The insert 16 is injected from an injection nozzle (not shown) arranged at the mouth of the pile on the ground, and filled with its own weight against the groundwater pressure. At this time, in order to prevent the backing material from escaping to the natural ground side, the escape prevention seal is maintained around the tip of the cylindrical tube at the bottom end so that the state in contact with the hole wall is maintained when the cylindrical tube is dropped. A material is attached (details will be described later). The backing material 16 is kneaded away from the work site and pumped to an injection nozzle placed at the mouth of the pile and injected automatically or semi-automatically (an operator can open the nozzle while monitoring the filling status) In such a case, it is possible to cope with a narrow work site. The excavator's excavator bit 12 is provided with an expansion / contraction mechanism. By excavating with the bit extended, the excavator drills with a diameter larger than that of the cylindrical tube 14, and when the operation is completed, the bit is contracted to contact the circular pipe. Can be raised without

FIG. 2 is a view showing a state in which the cylindrical tube is dropped and filled with the backing material.
The multi-stage cylindrical tube 14 and the hole wall 15 are in close contact with each other by the backing material 16, and the backing material is solidified over time, and the earth pressure from the hole wall is transferred to the cylindrical tube 14 through the backing material. Since it can be supported, the hole wall can be protected regardless of the formation. Further, since the backing material 16 is viscous, it follows the movement of dropping of the cylindrical tube 14 by its own weight, and the cylindrical tube and the hole wall are always brought into close contact with each other, and the ground reaction force and shear resistance from the natural ground are applied to the cylinder. The tube and the ground can be stabilized. Moreover, although the drilling mud 18 of a predetermined water level exists in a pile hole, since the specific gravity of the backing material 16 is large, it can be filled only by injection | pouring from the mouth of a pile, without requiring management of a muddy water level. . In addition, the filling speed of the backing material changes depending on the water head difference between the drilling mud and the backing material.If the drilling mud water level is lowered, the filling speed becomes faster, and if the drilling mud water level is raised, the filling speed becomes slower. The filling speed can be adjusted according to the level of the drilling mud. Moreover, when the backing material has a low specific gravity, it can be filled by lowering the level of the drilling mud.

FIG. 3 is a diagram for explaining an example of a sealing material for preventing escape of the backing material, and FIG. 4 is a cross section for explaining an example of attaching the sealing material for preventing escape of FIG. 3 around the tip of the cylindrical tube at the lowermost end. FIG.
As the sealing material of the present invention, it is possible to prevent the backing material from escaping, maintain the state in contact with the hole wall when the cylindrical tube is dropped, and withstand the frictional force generated between the hole wall and the sealing material. It is a condition. Therefore, in the example of FIG. 3, the sealing material 20 for preventing escape of the backing material is a combination of a sheet 21 made of vinyl, non-woven fabric, and the like and a mesh-like reinforcing material 22 made of metal, synthetic resin, or the like. Thus, the sheet-like reinforcing material 22 is disposed on the back side of the sheet 21 in contact with the backing material to support and reinforce the sheet.
In FIG. 4, along the bottom (tip) peripheral edge of the first-stage (bottom end) cylindrical tube 14, the escape prevention seal material 20 is arranged so that the sheet 21 is on the upper side and the mesh reinforcement 22 is on the lower side. It is attached with a bolt nut 25 or the like, and is extended from the bottom surface to a predetermined height so as to wrap around the cylindrical tube 14 and is installed. In this case, the sheet 21 and the mesh reinforcement 22 may be separated from each other or fixed. In this state, the cylinder tube is suspended and dropped with a wire (not shown) and filled with a backing material between the sealing material 20 and the cylindrical tube. There is a possibility that the weight is added and pushed downward, and the backing material flows out. Therefore, one end of the suspension wire 30 is fixed at an appropriate height position at a plurality of locations of the cylindrical tube, and the other end of each wire is fixed to the mesh-like reinforcing member 22 through the sheet 21 of the sealing material 20, and a plurality of suspension wires To be hung. By suspending with the wire, even if the weight of the backing material is added to the sealing material 20 from above, the state where the sealing material 20 is in contact with the hole wall can be maintained against this. In this case, since the backing material itself is solidified after a lapse of a predetermined time, the wire and the sealing material 20 only need to have a strength that can withstand during that time. In the above example, one end of the suspension wire is fixed to the cylindrical tube and the sealing material is suspended. However, the sealing material may be suspended at a plurality of locations from the ground.
In this example, when fixing the suspension wire 30 to the mesh-like reinforcing member 22, if a hole for passing the suspension wire is opened in the sheet 21, the backing material may leak. To prevent this, pulp, It is desirable to dispose components (leakage prevention agents) that cause clogging such as rayon, rock wool, sawdust, wire-drawn scum, and walnut shells in the vicinity of the wire attachment location. Thus, the state in which the sealing material 20 is in contact with the hole wall when the cylindrical tube 14 is dropped is maintained, and the mesh-like reinforcing material is disposed on the back side of the sheet to withstand the frictional force generated between the hole wall and the sealing material. It is possible to prevent the backing material having a large specific gravity from escaping downward. It is also possible to prevent the backing material from escaping below the pile by increasing the water level (mud pressure) of the drilling mud.
In the above example, a mesh-like reinforcing material is used as a reinforcing material for the sheet. However, a reinforcing material made of a planar material that is not mesh-like may be used, and a rubber plate, a steel plate, or the like may be used as a sealing material. If a material with high strength is used, a single-sheet configuration may be used. In the above example, the sealing material cannot be supported by the sealing material alone, so the sealing material is hung with a wire. However, if the strength of the sealing material is large, the wire may be omitted. If the length is longer than the total length of each cylindrical tube and the end portion is on the ground, the wire may be omitted. For example, the wire may be omitted when the pile length is relatively short and the end of the sealing material comes out on the ground.

DESCRIPTION OF SYMBOLS 1 ... Ground mountain, 3 ... Station platform, 5 ... Temporary enclosure, 10 ... Excavator ground apparatus 10, 11 ... Rod, 12 ... Excavation bit, 13 ... Supporting jig, 14 ... Cylindrical tube, 15 ... Hole wall, 16 ... Backing material, 18 ... Drilling mud, 20 ... Sealing material, 21 ... Sheet, 22 ... Mesh reinforcement, 30 ... Hanging wire.

Claims (3)

Simultaneously with the excavation work of the cast-in-place pile, a plurality of cylindrical pipes having a diameter smaller than the pile hole and shorter than the depth of the excavated part or equivalent length are connected together and dropped along the hole wall, A pile hole wall protection method in which a gap between a wall and a cylindrical tube is filled with a backing material and closely adhered,
Wire tip around a cylindrical tube of the lowermost end, Rutotomoni fitted with a sealing material in contact with the bore wall when darken cylindrical tube to prevent escape of Urakomi material, cylindrical tube of the sealing material at a plurality of places or from the ground, The pile hole wall protection method characterized by being hung by. Pile pore walls protection method of claim 1, wherein the decor preventing material leaking to the wire attachment point near the escape-preventing sealant.   2. The pile hole wall protection method according to claim 1, wherein the sealing material is longer than the entire length of each cylindrical tube and has a length where an end portion is exposed to the ground.

Images