JP2010031544A - Hole wall protecting method of cast in place pile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simply perform protecting work for a hole wall concurrently with excavation work for a cast in place pile. <P>SOLUTION: In this hole wall protecting method of a cast in place pile, a hole wall pressurizing member 10 including a diameter enlarging means and having a smaller diameter than a pile hole is inserted in an excavated hole concurrently with the excavation work for the cast in place pile, and the hole wall pressurizing member is increased in diameter by the diameter enlarging means in the excavated hole to apply pressure to the hole wall, so that the hole wall is protected. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  Conventionally, as a hole wall protection method in the cast-in-place pile method, a method of protecting the hole wall of the entire pile length with liner plate, casing tube, etc., such as deep foundation method and Benoto method, earth drill method, reverse method, There is known a method of protecting a hole wall by a casing of a surface layer portion and a muddy water pressure or a fresh water pressure such as a BH method.

The present applicant uses a circular tubular formwork with a predetermined width as a hole protection method for deep foundation piles, fills concrete between the formwork and the ground at every predetermined depth excavation, solidifies the concrete, A method of protecting the hole wall by removing the tubular formwork and lowering it and filling concrete between the formwork and the natural ground while sequentially excavating is proposed (Patent Document 1).
JP-A-7-71182

  Since the construction method shown in Patent Document 1 builds a formwork manually in the pile hole, it is not possible to install an excavating machine in the pile hole, and the formwork cannot be performed unless the inside of the pile hole is in the air. Therefore, water pressure cannot be used for hole wall protection.

  In addition, press-fitting is performed while swinging a long standpipe, but heavy machinery is required, and it is necessary to remove the roof of the station building once for work between tracks, etc., and construction is difficult. Although there is a method of press-fitting while welding a short pipe, it takes time to weld, and a counterweight is required to take the reaction force during 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 problems, and an object thereof is to enable easy protection of a hole wall in parallel with excavation work of a cast-in-place pile.
The present invention relates to a method for protecting a hole wall of a cast-in-place pile,
In parallel with the excavation work of the cast-in-place pile, a hole wall pressurizing member having a diameter smaller than that of the pile hole provided with the diameter expanding means is inserted into the excavation hole, and the hole wall pressurizing member is expanded in the excavation hole by the diameter expanding means. The hole wall is protected by applying pressure to the hole wall.
Further, the present invention is characterized in that the hole wall pressurizing member is installed continuously or discontinuously in the depth direction of the pile.
In addition, the present invention is characterized in that the hole wall pressing member has a circular member.
Further, the present invention is characterized in that the circular member is a member divided in the circumferential direction, and a diameter expanding means for connecting the divided portions is provided.
Further, according to the present invention, the circular member is composed of two circular members having a predetermined width that are obliquely hinged so as to intersect with each other, and each circular member is arranged in a direction in which the two circular members are flush with each other. A diameter expanding means for rotating the lens at the hinge portion is provided.
Further, according to the present invention, the circular member is a circular member having a predetermined width that is obliquely divided in the circumferential direction, and a force is applied to the circular member so that the diagonally divided surfaces of the divided circular members are aligned. A diameter expanding means for adding is provided.
Further, the present invention is characterized in that the circular member is formed of a spirally wound member having a predetermined width, and is provided with a diameter expanding means for applying a force so that both ends of the spiral member are brought close to each other. To do.
Further, the present invention is characterized in that the circular member is made of a steel pipe having a predetermined height divided at a plurality of locations in the circumferential direction, and a diameter expanding means for connecting the divided locations is provided.
Further, the present invention is characterized in that the circular member is formed of a donut-shaped pressurizing bag, and is provided with a diameter expanding means for injecting and inflating a filler into the pressurizing bag.
Further, in the present invention, the circular member is formed of a steel plate ring to which a pressurizing device is attached, and is attached between the steel plate ring and the pressurizing device, and the diameter is increased by a plurality of coil springs or jacks that expand the pressurizing device. Means are provided.
Further, according to the present invention, the circular member is made of a steel pipe having a predetermined height with a pressurizing bag attached to the periphery thereof, and has a diameter expanding means for injecting a filler into the pressurizing bag to inflate it. It is characterized by.
In addition, the present invention is characterized in that a steel pipe and a pressure bag that are discontinuously installed in the depth direction of the pile are protected by sprayed concrete, a sheet, a net, or the like.
Further, the present invention provides a method for protecting a hole wall of a cast-in-place pile,
A water blocking block is arranged around a long steel pipe installed at the mouth of the pile via a water sealing packing, and the muddy water pressure in the steel pipe is applied to the hole wall.
Moreover, this invention is characterized by the above-mentioned long steel pipe having a small diameter above the ground surface.

  The present invention can simplify the hole wall protection work by pressurizing the pile hole wall in parallel with the excavation work of the cast-in-place pile.

Embodiments of the present invention will be described below. In addition, although the example which constructs a cast-in-place pile between tracks is demonstrated below, it cannot be overemphasized that this invention is not limited to a construction place.
FIG. 1 is a diagram illustrating an example of a hole wall protection method when constructing cast-in-place piles between tracks, and FIG. 2 is a plan view illustrating an example of a diameter-expandable steel pipe used for hole wall protection.
A work gantry 3 is installed between the tracks 2 and 2 that support the rail 1 and excavated with a bit at the tip of the excavator 4. A steel pipe 10 having a predetermined height for hole wall protection is set in the excavating device 4 and is sequentially inserted into the pile hole 5. The steel pipe 10 is a construction material for the purpose of protecting the hole wall 6, and since it is not a structural material, a circular member made of a thin steel plate or the like is used.

  An example of the steel pipe inserted into the pile hole 5 will be described with reference to the plan view of FIG. 2. For example, the steel pipe 10 is divided at two locations in the circumferential direction and connected by a diameter expansion mechanism 11 that is a diameter expansion means. The diameter expansion mechanism 11 is composed of, for example, a spring that is shrunk with a holding metal fitting or the like and hooked on the hook, and the spring expands when the hook is removed. It becomes the steel pipe 12 of a state (FIG.2 (b)). Further, the steel pipe 10 is divided at four locations in the circumferential direction and connected by a diameter expansion mechanism 11 (FIG. 2 (c)). Similarly, when the hook is removed, the spring extends and the diameter of the steel pipe 10 is reduced from the reduced diameter. You may make it become the steel pipe 12 of this. The locations where the steel pipe is divided and connected by the diameter expansion mechanism are arbitrary, such as two places, four places, or a larger number so that the diameter can be expanded uniformly, and may be appropriately selected according to the size of the pile hole, etc. . The diameter expansion mechanism is not limited to a mechanical means such as a spring, but may be a diameter expansion means using hydraulic pressure, atmospheric pressure, or the like. For example, the diameter expansion mechanism is expanded by press-fitting liquid or gas into an extendable bag. You may be in a diameter state. In addition, since cast-in-place piles are actually excavated in muddy water, there is resistance to muddy water when expanding the diameter, so it is necessary to have a diameter expansion force that exceeds the resistance of muddy water.

  The steel pipe 10 in such a reduced diameter state has a smaller diameter than the excavated pile hole 5 and can be easily inserted into the pile hole 5 by setting it in the excavator 4. Thus, when inserted to a predetermined position, the steel pipe 12 that has been expanded by operating the diameter expansion mechanism can apply pressure to the pile hole wall 6 to prevent collapse and stabilize. The steel pipe 10 in the reduced diameter state is sequentially inserted and installed as the pile hole is excavated, but can be easily inserted through the existing steel pipe 12 in the enlarged diameter state, so that the installation work is easy, and the excavation work The hole wall protection can be performed in parallel. The steel pipe 12 to be installed may be installed in a continuous state without a gap along the pile hole, or may be installed in a discontinuous state with a predetermined interval, depending on the state of the hole wall. May be selected as appropriate.

FIG. 3 is a diagram for explaining another example of a hole wall protection method for constructing cast-in-place piles between tracks.
A work gantry 3 is installed between the tracks 2 and 2 that support the rail 1 and is excavated with a bit at the tip of the excavator 4, while the suspension rack 7 has a predetermined height that is a circular member for hole wall protection. The steel pipe 20 is suspended and inserted into the pile hole 5 by its own weight. The steel pipe 20 is a corrugated member such as a liner plate or a flat plate member formed into a steel pipe as a circular member by on-site assembly or the like, and has a diameter smaller than the diameter of the pile hole 6 and a bag-like pressure bag on the back. 21 is attached. This steel pipe 20 is inserted into the pile hole 5 and inflated by injecting a liquid filler such as grout or cement milk into the pressure bag 21 by an injection device (not shown) which is a diameter expanding means at a predetermined position. Pressurize. The filler can then solidify and stably pressurize and protect the pile hole walls. Also in this example, since the steel pipe and the pressure bag having a smaller diameter than the pile hole are sequentially installed along with excavation, the installation work is easy, and the hole wall protection can be performed concurrently with the excavation work. The steel pipe 20 may be installed in a continuous state without a gap along the pile hole, or may be installed in a discontinuous state with a predetermined interval, and is appropriately selected according to the state of the hole wall. do it. In addition, when installing in a discontinuous state, it is desirable to protect between the steel pipe and the pressure bag with sprayed concrete, a sheet, a net, or the like. In addition, it is desirable to insert and install the steel pipe and the pressure bag into the pile hole using a bar or a weight.

FIG. 4 is a diagram for explaining another example of a hole wall protection method when constructing cast-in-place piles between tracks, and FIG. 5 is a plan view for explaining an example of a donut-shaped pressure bag used for hole wall protection. .
A work gantry 3 is installed between the tracks 2 and 2 that support the rail 1 and excavated with a bit at the tip of the excavator 4. The doughnut-shaped pressurizing bag 30 is set together at the pile mouth of the excavator 4, and sequentially inserted into the pile hole 5. The outer diameter of the pressurizing bag is smaller than the diameter of the pile hole 5 so that it can be easily inserted into the pile hole. Pressurize. Since the pressurized bag 30 in the small diameter state can be easily inserted through the enlarged bag 31, it is easy to install sequentially, and the hole wall protection can be performed in parallel with the excavation work.

  An example of a pressurized bag will be described with reference to the plan view of FIG. 5. For example, a donut-shaped bag (FIG. 5A) is filled with grout, cement milk or the like by an injection device which is a diameter expanding means (not shown). By injecting the material, the diameter of the bag 31 is increased (FIG. 5B), and the hole wall is pressurized and protected. Further, the inner diameter side of the donut-shaped bag body is composed of a steel plate ring 32 that can take a reaction force, and one end of a spring 33 that is a diameter expanding means is connected to the steel plate ring 32 at a plurality of locations and is reduced by hooking a hook or the like. (FIG. 5 (c)), the bag 31 (FIG. 5 (d)) is expanded by opening the spring at a predetermined position of the pile hole 5, and the hole wall is pressurized and protected. The diameter expanding means is not limited to a spring, and a jack or the like may be used. Also in this example, the bag may be installed in a continuous state without opening a gap along the pile hole, or may be installed in a discontinuous state with a predetermined interval, depending on the state of the hole wall. What is necessary is just to select suitably. As mentioned above, since the excavation of cast-in-place piles is actually excavation in muddy water, it is assumed that muddy water enters the bag, but there is no problem with pressurizing the hole wall with the bag. .

Next, with reference to FIGS. 6 to 9, an example of a hole wall pressurizing member that is inserted into a drilling pile hole in a state of a smaller diameter than the pile hole, expands the diameter by a diameter expanding means in the drilling hole, and applies pressure to the hole wall. explain. Various circular members described below are erection materials that pressurize the hole walls of the pile and are not structural materials, and therefore thin steel plates, PVC pipes, and the like can be used.
FIG. 6 is a view showing an example of a hole wall pressing member.
The circular member 50 having a predetermined width has a cutting portion 51 in the circumferential direction, and has a diameter smaller than that of the pile hole in the cut state, and this portion is a diameter-expanding mechanism which is a diameter-expanding means indicated by an arrow for convenience. 52. The diameter-expansion mechanism 52 is a screw type that can be expanded by turning the screw to open the cutting part or using a spring as described in FIG. 2, and is expanded at a predetermined position of the pile hole. The hole wall is pressurized by the circular member 50 by making the diameter.

FIG. 7 is a view showing another example of the hole wall pressing member.
In this example, two circular members 60 and 61 having a predetermined width are slanted so as to cross each other and connected by a hinge 62, and in this state, the diameter is smaller than that of a pile hole. The two circular members 60 and 61 in the small diameter state are inserted into predetermined positions of the pile holes, and the force of arrows A and B is applied to the circular member 60 by means of a diameter-expanding means (not shown). The circular member 61 is rotated in the clockwise direction, and the force of the arrows C and D is applied to the circular member 61 to rotate it counterclockwise around the hinge 62 so that both circular members are flush with each other. The diameter of the hole wall can be increased by rotating so as to overlap with each other, and the hole wall can be pressurized with a circular member.

FIG. 8 is a view showing another example of the hole wall pressing member.
In this example, the circular member 70 having a predetermined width is cut and divided obliquely (FIG. 8A), and in this state, has a smaller diameter than the pile hole. The circular member 70 in a small diameter state is inserted into the excavation hole, and the vertical force of arrows E and F is applied to the divided end portion of the circular member at a predetermined position of the excavation hole by a diameter expanding means (not shown). By doing so, the divided surfaces are matched (FIG. 8B). By doing so, the circular member 70 can expand its diameter and pressurize the hole wall.

FIG. 9 is a view showing another example of the hole wall pressing member.
In this example, a circular member 80 having a predetermined width is spirally wound with a diameter smaller than the diameter of the pile hole (FIG. 9A), and the circular member 80 wound spirally is used. The spiral is expanded by inserting force into the both ends of the circular member 80 from the vertical direction of the arrows G and H by a diameter expanding means (not shown) at a predetermined position of the drill hole at a predetermined position of the drill hole. (FIG. 9B). By doing so, the spiral plate 80 can increase the diameter by reducing the number of turns, and pressurize the hole wall.

FIG. 10 is a diagram for explaining another example of pressurizing a pile hole wall.
In this example, a long steel pipe 30 for pressurization having a length of, for example, about 5 to 6 m, such as a stand pipe, is installed and excavated from the work gantry 3 higher than the excavator 4. At this time, according to the excavation depth, the steel pipe 30 is filled with muddy water that balances with the groundwater level, and the muddy water pressure is applied to the hole wall, thereby stabilizing the hole wall 6 and suppressing deformation. In addition, in order to apply muddy water pressure with the long steel pipe 30, it is necessary to arrange | position the water stop block 32 through the water stop packing 31 in the vicinity of the mouth of a pile, and to aim at pressure maintenance. In addition, in order to obtain the required hydraulic head pressure by the steel pipe 30, it is not necessary to use a thick pipe, so that it may be a thin pipe having a small diameter above the ground surface.

It is a figure explaining the example of the hole wall protection method at the time of constructing a cast-in-place pile between tracks. It is a top view explaining the example of the steel pipe which can be expanded for hole wall protection. It is a figure explaining the other example of the hole wall protection method at the time of constructing a cast-in-place pile. It is a figure explaining the other example of the hole wall protection method at the time of constructing a cast-in-place pile. It is a figure explaining the example of the doughnut-shaped pressurization bag used for a hole wall protection. It is a figure which shows the other example of a hole wall pressurization member. It is a figure which shows the other example of a hole wall pressurization member. It is a figure which shows the other example of a hole wall pressurization member. It is a figure which shows the other example of a hole wall pressurization member. It is a figure which shows an example of a hole wall protection mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Rail, 2 ... Track, 3 ... Work gantry, 4 ... Excavator, 5 ... Pile hole, 6 ... Hole wall, 7 ... Suspension mount, 10 ... Steel pipe, 11 ... Diameter expansion mechanism, 12 ... Diameter expansion state Steel pipe, 20 ... Steel pipe, 21 ... Pressurization, 30, 31 ... Pressurized bag, 32 ... Steel plate, 33 ... Spring, 40 ... Long steel pipe, 41 ... Water stop packing, 42 ... Water stop block, 50, 60, 61, 70, 80 ... circular member, 62 ... hinge.

Claims (14)

In the hole wall protection method for cast-in-place piles,
In parallel with the excavation work of the cast-in-place pile, a hole wall pressurizing member having a diameter smaller than that of the pile hole provided with the diameter expanding means is inserted into the excavation hole, and the hole wall pressurizing member is expanded in the excavation hole by the diameter expanding means. A method for protecting a hole wall of a cast-in-place pile, wherein the hole wall is protected by applying pressure to the hole wall by diameter. The method for protecting a hole wall of a cast-in-place pile according to claim 1, wherein the hole wall pressing member is continuously or discontinuously installed in the depth direction of the pile. The method for protecting a hole wall of a cast-in-place pile according to claim 2, wherein the hole wall pressing member includes a circular member. 4. The cast-in-place pile wall protection method according to claim 3, wherein the circular member is formed of a member divided in a circumferential direction, and a diameter expanding means for connecting the divided portions is provided. The circular member is composed of two circular members with a predetermined width that are obliquely hinged so as to intersect with each other, and the circular members are rotated by hinge portions in a direction in which the two circular members are flush with each other. The method for protecting a hole wall of a cast-in-place pile according to claim 3, wherein a means for expanding the diameter is provided. The circular member is composed of a circular member having a predetermined width that is obliquely divided in the circumferential direction, and a diameter expanding means for applying a force to the circular member so as to match the oblique division surfaces of the divided circular members is provided. The method for protecting a hole wall of a cast-in-place pile according to claim 3. 4. The cast-in-place pile hole according to claim 3, wherein the circular member is formed of a spirally wound member having a predetermined width, and is provided with a diameter expanding means for applying a force so that both ends of the spiral member are brought close to each other. Wall protection method. 4. The cast-in-place pile hole wall protection according to claim 3, wherein the circular member is formed of a steel pipe having a predetermined height divided at a plurality of locations in the circumferential direction, and is provided with a diameter expanding means for connecting the divided portions. Method. The method for protecting a hole wall of a cast-in-place pile according to claim 3, wherein the circular member is formed of a donut-shaped pressurizing bag, and includes a diameter expanding means for injecting a filler into the pressurizing bag to inflate it. The circular member is formed of a steel plate ring to which a pressurizing device is attached, and is provided between the steel plate ring and the pressurizing device, and includes a diameter expanding means including a plurality of coil springs or jacks for inflating the pressurizing device. The method for protecting a hole wall of a cast-in-place pile according to Item 3. 4. The cast-in-place according to claim 3, wherein the circular member is made of a steel pipe having a predetermined height with a pressurizing bag attached to the circumference thereof, and has a diameter expanding means for injecting and inflating a filler into the pressurizing bag. Pile hole wall protection method. The method for protecting a hole wall of a cast-in-place pile according to claim 11, wherein a steel pipe and a pressure bag that are discontinuously installed in the depth direction of the pile are protected by sprayed concrete, a sheet, a net, or the like. In the hole wall protection method for cast-in-place piles,
A method for protecting a hole wall of a cast-in-place pile, characterized in that a water stop block is arranged around a long steel pipe installed at the mouth of the pile via a water stop packing, and mud pressure in the steel pipe is applied to the hole wall. The method for protecting a hole wall of a cast-in-place pile according to claim 13, wherein the long steel pipe has a smaller diameter from the ground surface.

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