JP3935473B2 - Tip preload cast-in-place pile method and pile tip preload device - Google Patents

Description

  The present invention suppresses settlement of cast-in-place concrete piles by applying a load (hereinafter referred to as “preload”) to the ground at the bottom of the pile hole of cast-in-place concrete pile (hereinafter referred to as “pile tip ground”) in advance. The present invention relates to a tip preload cast-in-place pile method and a pile tip preload device used in this method.

  Cast-in-place concrete piles form a pile with a concrete structure in the ground by drilling a hole in the ground from the ground, placing a reinforcing member such as a reinforcing bar in the hole and placing concrete. is there. For this reason, the diameter and length of a pile can be enlarged compared with the driving pile which drives the pile manufactured in the factory into the ground, and it was advantageous in the case of the foundation etc. which require a big bearing force.

  However, cast-in-place concrete piles cause subsidence when a load is applied from above the piles after the concrete is cast and the piles are formed for the following reasons.

  (A) Although the ground in the ground is consolidated by a load such as soil stacked on the upper side, when the pile hole is drilled, the ground stress at the bottom of the pile is released, so that the ground is loosened.

  (B) When a pile hole is drilled through a gravel layer that has been submerged by groundwater, groundwater eruption (boiling) occurs, and the part where the gravel particles flow out loosens unevenly.

  (C) Pile hole drilling is performed while filling the pile hole with water mixed with particles such as bentonite to prevent the hole wall from collapsing, but the bottom of the pile hole at the tip of the pile is ground. A soft heterogeneous portion (slime portion) in which the fine soil particles drilled are precipitated is formed.

  (D) The ground itself in which the pile hole is drilled is heterogeneous depending on the location, and the ground strength varies.

  If the pile sinks, it will have adverse effects such as excessive force acting on the structure provided on the upper part of the pile. Conventionally, the tip support force of cast-in-place concrete piles is evaluated smaller than the tip support force of driven piles by design. Was.

  Moreover, as a method for suppressing the settlement of cast-in-place concrete piles, “tip pile method” has been proposed, but it is very expensive.

  For this reason, as a method of enhancing the bearing capacity of the pile tip ground at the bottom of the pile easily and at low cost, the applicant places concrete on the top with the injection bag body arranged at the pile tip, and after hardening the concrete A method of injecting injection material into the injection bag body and inflating the injection bag body downward from the pile tip to give a preload to the pile tip ground and pre-compress the pile tip ground to suppress subsequent pile settlement. (Hereinafter referred to as “tip preload cast-in-place pile method”) has been proposed (see Patent Document 1).

  As one application example of this tip preload cast-in-place pile method, a method using an injection bag body sewed with a water-permeable sheet-like material (hereinafter referred to as “water-permeable infused bag type tip preload cast-in-place pile method”). There is. In this water permeable bag type tip preload cast-in-place pile method, the injection pressure is managed at the pile head.

  However, the above-described water-permeable infusion bag type tip preload cast-in-place pile method has the following points to be improved.

  (I) There was a problem that the injection material was likely to leak from the injection bag body and the sewing portion.

(Ii) An injection engineer who manages the injection pressure must be stationed for each pile head, and should be improved from the viewpoint of efficient operation of personnel at the construction site, and labor cost Therefore, there is a growing demand for improvement from the viewpoint of reducing construction costs.
JP 2001-214438 A

  The present invention has been made to solve the above-mentioned problems, and the problem to be solved by the present invention is that there is no leakage of the injection material from the injection bag body and the like, and the tip preload place where monitoring for each pile is unnecessary. An object of the present invention is to provide a pile driving method and a pile tip preloading device used for the method.

In order to solve the above problems, the tip preload cast-in-place pile method according to the present invention is:
Pile hole drilling process for drilling pile holes for cast-in-place concrete piles in the ground;
Next, a reinforcing bar basket and an injection bag body attached to the lower end of the reinforcing bar basket are set in the pile hole, and the injection bag body is installed so as to face the pile tip ground at the bottom of the pile hole.・ Infusion bag body setting process;
Next, a concrete placing process for placing and hardening concrete in the pile hole to form a cast-in-place concrete pile in the ground,
Next, an injection material is injected into the injection bag body by injection means, the bottom of the injection bag body is pressed in the pile bottom direction, which is the direction toward the pile bottom, and a preload is loaded on the pile tip ground. In the tip preload cast-in-place pile method, which has a preload process to increase the bearing capacity of the pile tip ground and reduce the pile settlement amount,
The injection bag body is made of a bag material having water impermeability, and is formed by adhering or pressure bonding or welding the bag body material ,
The outer side of the injection bag body is covered with a bag body protection member, and the bag body protection member is made of an inner layer material having a property of being impermeable and having a slippery surface and is disposed outside the injection bag body. And an outer layer protective member that is made of an outer layer material that is impervious to water and has high breaking strength, and is disposed outside the inner layer protective member .

In the above-mentioned tip preload cast-in-place pile method, preferably,
Said injection means includes an injection pump, through an injection hose upper to the infusion pump is connected, a discharge hose upper end is connected to the discharge device, the infusion bag body while being accommodated in said injection bag body An infusion bag inner tube having an injection end connected to the injection hose and connected to the discharge hose and connected to the discharge hose,
When the injection pressure exceeding the valve opening pressure that is a predetermined pressure is applied, the injection bag inner tube allows the injection material to flow into the injection bag body and the injection pressure is equal to or lower than the valve opening pressure. Has a check valve that does not allow the injection material to flow into the injection bag body and prevents the backflow of the injection material in the injection bag body to the pipe in the injection bag.

  In the tip preload cast-in-place pile method, preferably, the infusion bag inner tube is made of a hard material and has an outflow hole, and a tubular elastic tube made of a rubber-based material is disposed outside the infusion bag inner tube. The check valve is configured by being fitted to close the outflow hole, and when the injection pressure exceeds the valve opening pressure, the injection material comes out of the outflow hole and the pipe in the injection bag and the It presses out while pushing up between the elastic tubes and is injected into the injection bag body.

  Further, in the above-mentioned tip preload cast-in-place pile method, preferably, an injection hose penetration portion where the injection hose penetrates the injection bag body and a discharge hose penetration portion where the discharge hose penetrates from the injection bag body An injection material leakage preventing member for preventing leakage of the injection material in the injection bag body is installed.

Moreover, the pile tip preloading device according to the present invention is
An injection bag body attached to the lower end of the reinforcing steel cage of the cast-in-place concrete pile and set in the hole of the pile, and an injection means for injecting an injection material into the injection bag body, the injection bag body with the injection material In the pile tip preloading device that presses the bottom of the pouring bag body in the pile bottom direction by injecting and loads a preload on the pile tip ground to increase the support force of the pile tip ground and reduce the amount of pile settlement ,
The injection bag body is made of a bag material having water impermeability, and is formed by adhering or pressure bonding or welding the bag body material ,
The outer side of the injection bag body is covered with a bag body protection member, and the bag body protection member is made of an inner layer material having a property of being impermeable and having a slippery surface and is disposed outside the injection bag body. And an outer layer protective member that is made of an outer layer material that is impervious to water and has high breaking strength, and is disposed outside the inner layer protective member .

In the above pile tip preloading device, preferably,
Said injection means includes an injection pump, through an injection hose upper to the infusion pump is connected, a discharge hose upper end is connected to the discharge device, the infusion bag body while being accommodated in said injection bag body An infusion bag inner tube having an injection end connected to the injection hose and connected to the discharge hose and connected to the discharge hose,
When the injection pressure exceeding the valve opening pressure that is a predetermined pressure is applied, the injection bag inner tube allows the injection material to flow into the injection bag body and the injection pressure is equal to or lower than the valve opening pressure. Has a check valve that does not allow the injection material to flow into the injection bag body and prevents the backflow of the injection material in the injection bag body to the pipe in the injection bag.

  In the above pile tip preloading device, preferably, the infusion bag inner tube is made of a hard material and has an outflow hole, and a tubular elastic tube made of a rubber-based material is disposed outside the infusion bag inner tube. When the injection pressure exceeds the valve opening pressure, the injection material comes out of the outflow hole and the injection bag inner tube and the elastic tube. The pressure is pushed out and injected into the injection bag body.

  In the above pile tip preloading device, preferably, the injection hose penetration part through which the injection hose penetrates the injection bag body and the discharge hose penetration part through which the discharge hose penetrates from the injection bag body An injection material leakage preventing member for preventing leakage of the injection material in the injection bag is installed.

  According to the tip preload cast-in-place pile method and the pile tip preload device according to the present invention, a pile hole drilling step of drilling a pile hole for a cast-in-place concrete pile in the ground, then a reinforcing bar cage, and the reinforcing bar cage Reinforcing bag basket / injection bag body setting step of setting the injection bag body attached to the lower end of the pile hole in the pile hole, and setting the injection bag body to face the pile tip ground at the bottom of the pile hole, A concrete placing step in which concrete is cast in the pile hole and hardened to form a cast-in-place concrete pile in the ground, and then an injection material is injected into the injection bag body by an injection means, Preloading work that presses the bottom of the infusion bag body toward the bottom of the pile, which is the direction toward the bottom, and loads the preload on the pile tip ground to increase the support force of the pile tip ground and reduce the pile settlement amount In the tip preload cast-in-place pile method and the pile tip preload device used for this method, the infusion bag body is made of an impermeable bag body material, and the bag body material is bonded, pressure-bonded or welded. Therefore, the injection material is prevented from leaking from the injection bag body. Further, the infusion means includes the infusion pump, the infusion hose connected to the top of the infusion pump, the discharge hose connected to the top of the infusion pump, the infusion bag and the infusion bag. An infusion bag inner tube is arranged to penetrate the body, the injection end is connected to the injection hose and the discharge end is connected to the discharge hose, and a predetermined pressure is applied to the injection bag inner tube. When an injection pressure exceeding the valve opening pressure is applied, the injection material is caused to flow into the injection bag body, and when the injection pressure is equal to or lower than the valve opening pressure, the injection material is input into the injection bag body. Since a check valve is provided for preventing inflow and preventing backflow of the injection material in the injection bag body to the pipe in the injection bag, an engineer who manages the injection pressure is provided for each pile head of each pile. There is no need to be resident, Has a remarkable effect of it it is possible to achieve efficient operation of personnel, and with reduced labor costs cost can be reduced construction costs, as in.

  The embodiment described below forms an infusion bag which is an infusion bag body by adhering or crimping or welding an impermeable bag body material without sewing, and as an infusion means, an infusion pump and An infusion hose with an upper end connected to the infusion pump, a discharge hose with an upper end connected to the infusion pump, and an injection end connected to the infusion hose that is housed in the infusion bag and penetrates the infusion bag In addition, if an injection pressure exceeding the valve opening pressure, which is a predetermined pressure, is applied to the injection bag inner tube, the injection material flows into the injection bag. In addition, when the injection pressure is lower than the valve opening pressure, a check valve is provided to prevent the injection material from flowing into the injection bag and to prevent the backflow of the injection material in the injection bag to the tube inside the injection bag. And obedience And infusion bags pile tip preloading device at the distal preload place pile construction method, the lower end of the injection hose and the discharge hose is readily carried out by applying a relatively simple changes. In addition, when injecting the injection material for preloading, no special equipment or mechanism is required, and the injection for preloading can be performed by the same injection plant and injection pump as in the past, for realizing the present invention. This is the best configuration.

  Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of a tip preload cast-in-place pile method according to a first embodiment of the present invention and a pile tip preload device used in this method.

  As shown in FIG. 1, in the tip preload cast-in-place pile method of this embodiment, first, a pile hole 10 for cast-in-place concrete pile is drilled in the ground (see FIG. 1A). “Pile hole drilling process”.) The hole in the pile hole 10 is water mixed with particles such as bentonite to prevent the pile hole side wall 10a from collapsing (hereinafter referred to as “drilling liquid”). Is performed while filling the pile hole 10. In this case, a slime portion 10c, which is a soft heterogeneous portion in which fine soil particles having been drilled in the ground, are formed at the bottom portion 10b of the pile hole 10 which is the tip (lower end) of the pile.

  Next, the reinforcing bar basket 11 is manufactured in advance outside the pile hole 10. The reinforcing bar basket 11 is assembled into a cylindrical basket shape by binding a plurality of rod-shaped main reinforcing bars arranged in the longitudinal direction and a plurality of hoop reinforcing bars (band reinforcing bars) arranged in a ring shape with a lentil iron wire. A tip preload unit 12 having an infusion bag 1 and a frame 2 to be described later is attached to the lower end of the rebar basket 11, and the rebar basket 11 with the tip preload unit 12 attached to the lower end is suspended by a crane 13 or the like. Sunk into. Thereby, the front-end | tip preload unit 12 is installed so that it may oppose the pile front-end | tip ground of the bottom part 10b of the pile hole 10 (refer FIG.1 (B). Hereinafter, this process is called "reinforcing bar basket and injection bag setting process"). . In addition, since the slime part 10c has settled on the bottom part 10b of the pile hole 10, the injection bag 1 is mounted on the slime part 10c, and opposes the pile front-end ground of the bottom part 10b of the pile hole 10. Installed.

  Here, the tip preload unit 12 will be described. 2 is a diagram showing a more detailed configuration of the tip preload unit 12 in the pile tip preload device 101 shown in FIG. 1, FIG. 2 (A) is a perspective view, FIG. 2 (B) is a sectional view, respectively. Show. 3 is a diagram showing a more detailed configuration of the infusion bag inner tube 4 and the infusion bag 1 in the vicinity thereof in the tip preload unit shown in FIG. 2, and FIG. 3 (A) is a cross-sectional view of the position (infusion). 3B is a perspective view of the infusion bag inner tube 4 and the rubber tube 5, and FIG. 3C is an infusion bag inner tube 4 and the rubber tube. 5 is a cross-sectional view (cross-sectional view perpendicular to the longitudinal direction of the infusion bag inner tube 4) in a state equal to or lower than the valve opening pressure of FIG. 5, and FIG. Cross-sectional views (cross-sectional views perpendicular to the longitudinal direction of the infusion bag inner tube 4) in the state of exceeding are shown respectively. Moreover, FIG. 4 is a figure which shows the condition of a reinforcing bar basket and an injection | pouring bag setting process among the procedures of the tip preload cast-in-place pile method shown in FIG. Moreover, FIG. 5 is a conceptual diagram which shows the condition of a preload process among the procedures of the tip preload cast-in-place pile method shown in FIG.

  As shown in FIG. 2, the tip preload unit 12 includes an injection bag 1 and a frame 2.

  The infusion bag 1 is a hollow bag made by using a bag material in which a material having water impermeability (water blocking property), pressure resistance, and flexibility is formed in a sheet shape. In this case, the infusion bag 1 is formed into a bag shape by bonding the above-mentioned bag body material with an adhesive, pressure bonding, or heat welding, pressure and heating heat pressure bonding, etc. Not used. Examples of the material constituting the injection bag 1 include synthetic resin materials, for example, plastics such as thermoplastic resins and thermosetting resins, and specifically, polyethylene, polyvinyl chloride, vinylidene chloride, polypropylene, polyamide, and the like. Also, as the bag material, rubber materials (including synthetic rubber and elastomer materials) can be used. Moreover, as a bag body material, the sheet-like member, film-like member, film-like member, etc. which consist of these materials are mentioned. The infusion bag 1 is provided with an infusion hose penetration portion 1e that is a portion for the infusion connection of the infusion hose 17b and a drain hose penetration portion 1f that is a portion for the discharge hose 17c to continue to penetrate. The injection bag 1 corresponds to the injection bag body in the claims.

  The frame 2 is made of a material such as metal including steel, and has a plurality of annular portions 2a and a plurality of radial portions 2b that join the annular portions 2a, and is formed in a shape like a colander as a whole. Yes. The frame 2 is disposed between the lower end of the reinforcing bar 11 and the injection bag 1, and the injection bag 1 is fixed to the frame 2 by a fixture 3 such as a steel wire.

  With such a configuration, the lower portion (the bottom portion 1a and the side portion 1b) of the injection bag 1 serving as the bottom portion of the tip preload unit 12 is convex in a direction toward the pile hole bottom portion 10b (hereinafter referred to as “pile bottom direction”). Such as a bowl shape, a hemisphere shape, a paraboloid shape, a truncated cone shape, and the like. For this reason, in the reinforcing bar basket / infusion bag setting step, the resistance force from the drilling liquid when the tip preload unit 12 is set in the pile hole 10 (hereinafter, referred to as “resistance value at the time of setting”) is reduced. (See FIG. 4).

  After the above-described rebar basket / injection bag laying process, the ready-mixed concrete 15a manufactured in a concrete plant (not shown) is poured into the pile hole 10 using the concrete pump 14a and the concrete pumping pipe 14b. Install and cure. As a result, a cast-in-place concrete pile is formed in the ground (see FIG. 1C. Hereinafter, this process is referred to as a “concrete placing process”).

  Next, after confirming that the concrete has hardened and developed a predetermined strength as in 15b, the injection material 17 is injected into the injection bag 1 of the tip preload unit 12 using the injection device 17. The injection device 17 includes a mixer 17m, an injection pump 17a, an injection hose 17b, a discharge hose 17c, an injection bag inner tube 4 (see FIGS. 2B and 3), a discharger 17d, and a valve B1. -B4 and pressure sensors S1 and S2.

  The mixer 17m is provided with a stirring blade or the like inside the container, kneads the input materials (for example, cement, water, additives, etc.), generates an injection material G (for example, cement milk), and supplies it to the injection pump 17a. send. The injection pump 17a is a known pump that applies pressure to the fluid injection material G and pushes it out. The injection pump 17a is installed on the ground near the pile head and sends the injection material G into the injection hose 17b. As the injection material G, a substance that is hardened after being injected in a fluid state is used. In addition to the above-described cement milk, a resin-based injection material or the like is used. The injection hose 17b is a tubular member (pipe) formed of a flexible material, for example, synthetic rubber, rubber-based material, and the like. FIG. 1 (D), FIG. 2 (B), and FIG. ), The upper end thereof is attached to the outlet of the infusion pump 17a, and the lower end thereof is inserted into the infusion bag 1 from the infusion hose penetration portion 1e of the infusion bag 1, and the one end 4a (hereinafter referred to as the infusion bag inner tube 4). , Referred to as “injection end”).

  Further, the discharge hose 17c is a tubular member (pipe) formed of a flexible material, for example, synthetic rubber, rubber-based material, and the like. FIG. 1 (D), FIG. 2 (B), and FIG. ), The lower end thereof is inserted into the infusion bag 1 from the discharge hose protruding portion 1f of the infusion bag 1 and connected to the other end 4b of the infusion bag inner tube 4 (hereinafter referred to as “discharge end”). The upper end is attached to the inlet of the discharger 17d. 4 and 5, the illustration of the discharge hose 17c is omitted. The discharger 17d is a known pump capable of sucking air, fluid injection material, and the like, and is installed on the ground near the pile head.

  The valves B1 and B2 are valves that can be controlled to be opened and closed by an actuator (not shown) or the like, and are installed in the injection hose 17b (for example, a position sandwiching the pressure sensor S1). The valves B3 and B4 are valves that can be opened and closed by an actuator (not shown) or the like, and are installed in the discharge hose 17c (for example, a position sandwiching the pressure sensor S2). Moreover, the pressure sensor S1 is installed on the ground pile head or the like of the injection hose 17b and detects the pressure in the injection hose 17b. Further, the pressure sensor S2 is installed on a pile head or the like on the ground of the discharge hose 17c and detects the pressure in the discharge hose 17c.

  Using the injection device 17 as described above, for example, first, the valves B1 to B4 are opened, the injection material G is sent from the injection pump 17a, and suction is performed by the discharger 17d. The exhaust bag 17d reaches the discharger 17d through the injection bag inner pipe 4 at the tip of the pile while discharging air in the pipe 17b and the injection bag inner pipe 4 and the discharge hose 17c. Then, if valve | bulb B4 is obstruct | occluded and the injection material G is sent out from the injection pump 17a in this state, the pressure (injection pressure) of the injection material G in the injection bag inner pipe 4 will rise. The situation of this injection pressure can be grasped by monitoring the pressure sensors S1 and S2 on the pile head side.

  In the case of the first embodiment, the infusion bag inner tube 4 is a tubular member made of a hard material, for example, a metal material such as steel or an aluminum alloy, a synthetic resin material, a ceramic material, or the like. An outflow hole 4 c is provided in the side portion of the infusion bag inner tube 4. In the vicinity of the outflow hole 4c, a tubular rubber tube 5 made of a rubber-based material (for example, synthetic rubber) is fitted on the outside of the infusion bag inner tube 4 so as to close the outflow hole 4c. For example, by setting the inner diameter of the rubber tube 5 to be smaller than the outer diameter of the infusion bag inner tube 4 and fitting the rubber tube 5 to the infusion bag inner tube 4, this state can be obtained. In this case, the length of the rubber tube 5 is set to be shorter than the length of the infusion bag inner tube 4. This is to make it easier to exert a check valve function described later.

  With the above configuration, when the injection pressure of the injection material G inside the injection bag inner tube 4 is a predetermined value (hereinafter referred to as “valve opening pressure”) or less, as shown in FIG. In addition, the injection material G inside the injection bag inner tube 4 is prevented from flowing out by the rubber tube 5. However, when the injection pressure of the injection material G inside the injection bag inner tube 4 exceeds the valve opening pressure, the injection material G is a rubber tube outside the outflow hole 4c as shown in FIG. After pushing out 5, the pressure between the infusion bag inner tube 4 and the rubber tube 5 is further pushed out to the outside of the infusion bag inner tube 4 and flows into the infusion bag 1 from the end of the rubber tube 5. In this way, the injection material G is injected into the injection bag 1. Thereafter, when the injection pressure drops below the above valve opening pressure, the rubber tube 5 is again brought into close contact with the outflow hole 4c due to the elastic force of the rubber-based material, so that it is injected into the injection bag 1. The injected material G cannot flow backward to the injection bag inner tube 4 by being blocked by the rubber tube 5 which is in close contact with the outflow hole 4c. That is, the rubber tube 5 and the outflow hole 4c constitute a check valve in the claims. The rubber tube 5 corresponds to the elastic tube in the claims.

  As described above, the injection material G is injected into the injection bag 1 of the tip preload unit 12. Thereby, the bottom 1a of the injection bag 1 is pressed in the pile bottom direction, and the preload is loaded on the pile tip ground. Along with this, the support force of the pile tip ground is increased and the amount of pile settlement is reduced (see FIG. 1D). Hereinafter, this process is referred to as a “preload process”. Here, the injection device 17 constitutes the injection means in the claims.

  In the above-described preloading process, the injection engineer on the ground can monitor the injection pressure in the injection hose 17b with the pressure sensor S1 and monitor the injection pressure in the discharge hose 17c with the pressure sensor S2. At this time, if the injection pressure exceeds the value of the valve opening pressure, the injection material G is automatically injected into the injection bag 1 by the combined action of the rubber tube 5 and the outflow hole 4c. In addition, the injection engineer on the ground does not need to be resident for each pile head of each pile, and it is only necessary to centrally monitor the detection value from each pressure sensor with an injection management device installed at a predetermined location on the site. .

  Further, in the infusion bag 1, the infusion hose 17b penetrates the infusion bag 1, the infusion hose penetration 1e, and the drain hose 17c in which the ejection hose 17c penetrates the infusion bag 1 are provided for preventing leakage of the infusate. Packing members 6a and 6b are attached (see FIG. 3A). Thereby, even if a high injection pressure acts, the injection material G is prevented from leaking outside the injection bag 1.

  Further, in the above-described rebar basket / infusion bag laying step, the air in the infusion bag 1 is extracted by another exhaust device (not shown) or the like, and the infusion bag 1 is contracted and thin. It has become.

  The pile tip ground is compressed by the preloading process. Thereafter, the injection material G in the injection bag 1 is cured as time passes while maintaining this state. After the injection material G is hardened, even if a structure is built on the top of the pile and the load from the upper structure is applied to the pile, the pile tip ground is pre-compressed by the preload, so the settlement of the pile is suppressed. The

  Further, as shown in FIG. 5B, the frame 2 is formed with a weakened section 21 by a hole, a notch or a reduced section in the radial part 2b, for example, and the sectional weakened part 21 is plastic. It is configured to be deformable. For this reason, when the tip preload unit 12 settles on the pile tip ground of the bottom 10b of the pile hole 10 by the reinforcing bar basket / injection bag laying step, the long axis direction D1 (hereinafter referred to as “pile axis direction”). .)) Acts on the frame 2, for example, the radial portion 2b of the frame 2 is deformed as indicated by 2b 'in FIG. 5B.

  Thereby, the whole flame | frame 2 deform | transforms so that it may collapse in the pile axial direction D1, as shown to FIG. 5 (A). By causing such “crushed deformation” of the frame 2, the depth of the pile hole 10 fluctuates from the design value due to construction errors or the like, and even if the pile hole becomes shallower than the design value, the tip preload unit 12 is accordingly changed. The height can be adjusted. When the injection material G is injected into the injection bag 1, the bottom of the injection bag 1 also presses in the direction D <b> 2 (hereinafter referred to as “pile wall direction”) toward the inner wall 10 a of the pile hole 10. A preload is also loaded on the side of the tip ground (see FIG. 5A).

  Further, since the frame 2 is crushed and deformed, and the side portion of the injection bag 1 is pressed against the inner wall 10a of the pile hole 10, the poured concrete 15a in the fluidized state is placed in the injection bag 1 when the pile concrete 15a is placed. There is no problem of preventing the preload from being applied to the ground of the pile bottom 10b by the hardened concrete without going around the top, and the expansion force of the injection bag 1 is directly applied to the preload on the pile tip ground 10b. It also has the advantage of being able to guess.

  Note that the frame 2 can be configured to be plastically deformable even if it is simply made of a metal material such as a steel material without providing a weakened section (21 or the like).

  The present invention can also be realized by configurations other than the first embodiment described above. FIG. 6 is a diagram showing the configuration and action of the tip preload unit 12A in the pile tip preload device 102 used in the tip preload cast-in-place pile method according to the second embodiment of the present invention.

  The feature of the tip preload unit 12A of the second embodiment is that the outer side of the infusion bag 1 of the first embodiment is covered with the inner layer protective member 7 and the outer side of the inner layer protective member 7 is covered with the outer layer protective member 8. It is. Since other configurations and operations are exactly the same as those in the first embodiment, the description thereof is omitted.

  The inner layer protection member 7 is a bag-shaped member made of an inner layer material having water-impermeable properties and having a property that the surface is slippery, for example, a sheet-like plastic. The inner layer protection member 7 has a shape and size larger than the shape and size when the infusion bag 1 is fully expanded, and does not restrain the injection bag 1 even when the infusion bag 1 is fully expanded. Designed to be In addition, an injection hose insertion port 7e is provided at the location of the inner layer protection member 7 corresponding to the injection hose penetration 1e of the injection bag 1, from which inside and outside air can enter and exit. Further, a discharge hose insertion port 7f is provided at a position of the inner layer protection member 7 corresponding to the discharge hose protruding portion 1f of the injection bag 1, from which the inside and outside air can enter and exit.

  The outer layer protective member 8 is a bag-shaped member made of a sheet-like plastic that is impermeable and has a high breaking strength, for example, a thicker sheet plastic than the inner layer protective member 7. The outer layer protection member 8 has a shape and size larger than the shape and size of the inner layer protection member 7 when the infusion bag 1 is fully expanded, and even when the injection bag 1 is fully expanded, the injection bag 1 and The inner layer protection member 7 is designed not to be restrained. Further, an injection hose insertion port 8e is provided at a location of the outer layer protection member 8 corresponding to the injection hose penetration 1e of the injection bag 1, from which inside and outside air can enter and exit. Further, a discharge hose insertion port 8f is provided at a location of the outer layer protection member 8 corresponding to the discharge hose protruding portion 1f of the injection bag 1, from which inside and outside air can enter and exit.

  With the above configuration, when the infusion bag 1 is inflated, the inner layer protection member 7 protects the infusion bag 1 and inflates in accordance with the inflated state of the infusion bag 1. At this time, since the surface of the inner layer protection member 7 has a slippery property, the frictional resistance between the injection bag 1 and the inner surface of the inner layer protection member 7 is small, and the outer surface of the inner layer protection member 7 and the outer layer protection member 8 The frictional resistance with the inner surface of the is also small. Thereby, the inner layer protection member 7 can easily follow the inflation of the infusion bag 1 and can be inflated inside the outer layer protection member 8 without any trouble as in the case of the infusion bag 1. The outer layer protection member 8 also expands in accordance with the inflated state of the infusion bag 1, but since it is a thick material, it has a high breaking strength, and even if there is a rake having a sharp corner near the pile bottom. The damage of the inner injection bag 1 can be prevented. In the above, the inner layer protection member 7 and the outer layer protection member 8 constitute a bag body protection member in the claims.

  The present invention is not limited to the above embodiments. Each of the above-described embodiments is an exemplification, and any device that has substantially the same configuration as the technical idea described in the claims of the present invention and has the same operational effects can be used. It is included in the technical scope of the present invention.

  For example, in each of the above embodiments, in the drilling process of the pile hole 10, the example of using the drilling liquid mixed with particles such as bentonite as the means for preventing the collapse of the pile hole side wall has been described. Pile hole drilling process by other methods, for example, pile hole drilling process using casing tube as means for preventing pile hole side wall collapse, hydrostatic pressure used as means for preventing pile hole side wall collapse It may be a pile drilling step or the like. Further, depending on the pile hole drilling process, the slime portion may not be formed at the bottom of the pile hole. In this case, the tip preload unit is directly installed on the bottom of the pile hole.

  Further, in the first embodiment described above, the infusion bag 1 is formed by adhering or pressure bonding or welding an impermeable bag body material, and the infusion pump 17a and the infusion pump 17a are used as the infusion means. An infusion hose 17b to which the upper end is connected, a discharge hose 17c to which the upper end is connected to the infusion pump 17a, and an infusion end 4a that is accommodated in the infusion bag 1 and is disposed so as to penetrate through the infusion bag 1. Is connected and the discharge hose 17c is connected to the discharge end 4b. The injection bag inner tube 4 is provided with an outflow hole 4c and fitted with a rubber tube 5, so that the valve opening pressure is a predetermined pressure. When an injection pressure exceeding 1 is applied, the injection material G is caused to flow into the injection bag 1 and when the injection pressure is equal to or lower than the valve opening pressure, the injection material G is injected into the injection bag 1. Without inflow and the structure to prevent backflow into infusion bag tube 4 of the injection material G in the infusion bag 1 was described, but the present invention is not limited to this example. This invention may be comprised only by forming the injection | pouring bag 1 by adhere | attaching or crimping | bonding or welding an impermeable bag body raw material.

  INDUSTRIAL APPLICABILITY The present invention can be implemented in a construction industry or the like that constructs a cast-in-place concrete pile as a foundation of a structure or a building, and can be used in these industries. Moreover, the infusion bag body and the infusion bag inner tube for the pile tip preloading device, or the bag body protection member can be manufactured in the plastic industry or the metal industry that manufactures plastic products, metal products, etc. Is available.

It is a figure which shows the structure of the tip preload cast-in-place pile construction method which is 1st Example of this invention, and the pile tip preload apparatus used for this construction method. It is a figure which shows the further detailed structure of the front-end | tip preload unit in the pile front-end | tip preload apparatus shown in FIG. It is a figure which shows the further detailed structure of the injection bag inner pipe | tube in the front-end | tip preload unit shown in FIG. 2, and the injection bag of the vicinity. It is a figure which shows the condition of a reinforcing bar basket and injection bag setting process among the procedures of the tip preload cast-in-place pile method shown in FIG. It is a conceptual diagram which shows the condition of a preload process among the procedures of the tip preload cast-in-place pile construction method shown in FIG. It is a figure which shows the structure and its effect | action of the front-end | tip preload unit in the pile front-end preload apparatus used for the front-end | tip preload cast-in-place pile construction method which is 2nd Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Injection bag 1a Bottom part 1b Side part 1c Upper part 1e Injection hose penetration part 1f Discharge hose penetration part 2 Frame 2a Annular part 2b, 2b 'Radial part 3 Fixing tool 4 Injection bag inner pipe 4a Injection end 4b Outlet end 4c Outflow hole 5 Rubber tube 6a, 6b Packing member for preventing injection material leakage 7 Inner layer protection member 7e Injection hose insertion port 7f Discharge hose insertion port 8 Outer layer protection member 8e Injection hose insertion port 8f Discharge hose insertion port 10 Pile hole 10a Pile hole side wall 10b Pile hole Bottom part 10c Slime part 11 Reinforcing bar 12 Tip preload unit 13 Crane 14a Concrete pump 14b Concrete pumping pipe 15a Ready-mixed concrete 15b Concrete after hardening 17 Injection device 17a Injection pump 17b Injection hose 17c Discharge hose 17d Discharge machine 17m Mixer 21 Break It weakened portions 101 and 102 pile tip preloading device B1~B4 valve D1 pile bottom direction D2 Kuikabe direction G injection material S1, S2 pressure sensor

Claims (8)

Pile hole drilling process for drilling pile holes for cast-in-place concrete piles in the ground;
Next, a reinforcing bar basket and an injection bag body attached to the lower end of the reinforcing bar basket are set in the pile hole, and the injection bag body is installed so as to face the pile tip ground at the bottom of the pile hole.・ Infusion bag body setting process;
Next, a concrete placing process for placing and hardening concrete in the pile hole to form a cast-in-place concrete pile in the ground,
Next, an injection material is injected into the injection bag body by injection means, the bottom of the injection bag body is pressed in the pile bottom direction, which is the direction toward the pile bottom, and a preload is loaded on the pile tip ground. In the tip preload cast-in-place pile method, which has a preload process to increase the bearing capacity of the pile tip ground and reduce the pile settlement amount,
The injection bag body is made of a bag material having water impermeability, and is formed by adhering or pressure bonding or welding the bag body material ,
The outer side of the injection bag body is covered with a bag body protection member, and the bag body protection member is made of an inner layer material having a property of being impermeable and having a slippery surface and is disposed outside the injection bag body. A tip preload cast-in-place pile method comprising: an inner layer protective member that is made of an outer layer material that is made of an outer layer material that is impervious and has high breaking strength, and is disposed outside the inner layer protective member . In the tip preload cast-in-place pile method according to claim 1,
The infusion means includes an infusion pump, an infusion hose with an upper end connected to the infusion pump, a drain hose with an upper end connected to a discharger, and is accommodated in the infusion bag body and penetrates the infusion bag body An infusion bag inner tube having an injection end connected to the injection hose and connected to the discharge hose and connected to the discharge hose,
When the injection pressure exceeding the valve opening pressure that is a predetermined pressure is applied, the injection bag inner tube allows the injection material to flow into the injection bag body and the injection pressure is equal to or lower than the valve opening pressure. The tip preload cast-in-place pile has a check valve that does not allow the injection material to flow into the injection bag body and prevents the backflow of the injection material in the injection bag body to the pipe of the injection bag. Construction method. In the tip preload cast-in-place pile method according to claim 2 ,
The infusion bag inner tube is made of a hard material and has an outflow hole, and a tubular elastic tube made of a rubber-based material is fitted on the outside of the infusion bag inner tube so as to close the outflow hole, thereby the check. When the injection pressure exceeds the valve opening pressure, the injection material comes out of the outflow hole and is pressed out while pushing up between the injection bag inner tube and the elastic tube, and the injection bag body Tip preload cast-in-place pile method, characterized by being injected into the inside . In the tip preload cast-in-place pile method according to claim 2 ,
An injection material for preventing leakage of the injection material in the injection bag body at the injection hose penetration portion where the injection hose penetrates the injection bag body and the discharge hose penetration portion where the discharge hose penetrates from the injection bag body Tip preload cast-in-place pile construction method, characterized in that leakage prevention members are installed . An injection bag body attached to the lower end of the reinforcing steel cage of the cast-in-place concrete pile and set in the hole of the pile, and an injection means for injecting an injection material into the injection bag body, the injection bag body with the injection material In the pile tip preloading device that presses the bottom of the pouring bag body in the pile bottom direction by injecting and loads a preload on the pile tip ground to increase the support force of the pile tip ground and reduce the amount of pile settlement ,
  The injection bag body is made of a bag material having water impermeability, and is formed by adhering or pressure bonding or welding the bag body material,
  The outer side of the injection bag body is covered with a bag body protection member, and the bag body protection member is made of an inner layer material having a property of being impermeable and having a slippery surface and is disposed outside the injection bag body. An inner layer protective member that is made of an outer layer material that is impermeable and has high breaking strength, and is disposed outside the inner layer protective member.
  Pile tip preload device characterized by. In the pile tip preloading device according to claim 5 ,
The infusion means includes an infusion pump, an infusion hose with an upper end connected to the infusion pump, a drain hose with an upper end connected to a discharger, and is accommodated in the infusion bag body and penetrates the infusion bag body An infusion bag inner tube having an injection end connected to the injection hose and connected to the discharge hose and connected to the discharge hose,
When the injection pressure exceeding the valve opening pressure that is a predetermined pressure is applied, the injection bag inner tube allows the injection material to flow into the injection bag body and the injection pressure is equal to or lower than the valve opening pressure. The pile tip preloading device has a check valve that prevents the injection material from flowing into the injection bag body and prevents backflow of the injection material in the injection bag body to the pipe in the injection bag . In the pile tip preloading device according to claim 6 ,
The infusion bag inner tube is made of a hard material and has an outflow hole, and a tubular elastic tube made of a rubber-based material is fitted on the outside of the infusion bag inner tube so as to close the outflow hole, thereby the check. When the injection pressure exceeds the valve opening pressure, the injection material comes out of the outflow hole and is pressed out while pushing up between the injection bag inner tube and the elastic tube, and the injection bag body Pile tip preloading device characterized by being injected into the inside . In the pile tip preloading device according to claim 6 ,
An injection material for preventing leakage of the injection material in the injection bag body at the injection hose penetration portion where the injection hose penetrates the injection bag body and the discharge hose penetration portion where the discharge hose penetrates from the injection bag body A pile preloading device characterized in that a leakage prevention member is installed .

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