JPH0610345A - Confirmation and increase method for support force of cast-in-place pile - Google Patents

Abstract

PURPOSE:To achieve confirmation of the support force of a cast-in-place pile and the support force of a tip ground. CONSTITUTION:First, a cylindrical auxiliary device 10 having partition plate 20 arranged in the given height of the interior thereof is installed in the bottom of a pile hole H and after the lower end of a press-in pipe 40 is caused to front on a position above the partition plate 20 of the auxiliary device 10, concrete is placed in the pile hole H to build a pile 50. When the pile 50 is cured, curable fluid 60 is pressed in through the press-in pipe 40 with a given pressure, and a pile tip part is divided into upper and lower sections in a position above the partition plate 20 of the auxiliary device 10. The tip ground is consolidated through peripheral surface friction of the pile 50 serving as a reaction force to increase a support force and the support force is confirmed by means of the press-in force of fluid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cast-in-place pile, and more particularly to a method for confirming the supporting force of a cast-in-place pile to be constructed and increasing the tip supporting force.

[0002]

2. Description of the Related Art As is well known, cast-in-place piles are constructed by excavating a pile hole in advance, inserting a reinforcing bar cage into this pile hole, and then placing concrete to support it. It is difficult to confirm the force. In addition, when excavating a pile hole, earth pressure is released and the tip ground loosens, and sediment easily accumulates, and the pile after construction will sink over time, that is, the quality of the constructed pile is high. There was a risk of defects.

Conventionally, as a method of confirming the supporting force of the constructed pile, a load test is known in which a plurality of piles are used as reaction piles and a load to be tested is applied with a hydraulic jack or the like (hereinafter, referred to as a load test). "Conventional loading test"). On the other hand, as a simple loading test, a jack device is installed at the tip of the test pile, that is, the bottom of the pile hole, and the jack device is driven after the pile is constructed, and the tip supporting force and the pile peripheral surface friction force are measured. It is known that a load test can be easily performed without using a reaction force pile (for example, JP-A-61-225628,
Hereinafter, such as JP-A-62-291333, "simple loading test").

On the other hand, as a means for strengthening the ground at the tip of the pile to increase the bearing capacity of the pile after construction and preventing settlement, for example, a reaction force is taken by a hole wall or a casing pipe before construction of the pile. A method is known in which a large number of rod-shaped rigid bodies or cone blocks divided into concentric circles are pushed into the bottom of the hole with a jack or the like to improve the tip supporting force (for example, JP-A 1-223214, JP-A 2-23214). No. 24415).

Further, after a rubber bag or a jack housed in a restraint container is installed at the bottom of the hole, a cast-in-place pile is formed, and a pressure fluid is injected into the rubber bag or jack from the ground to inflate it, and the peripheral surface of the pile is A method is known in which friction is used as a reaction force to consolidate the tip ground and improve the supporting force (for example, Japanese Patent Laid-Open No.
125015, JP-A-3-90706, etc.). In addition, multiple pipes are installed over the entire length of the pile hole, and after the pile is constructed, a hardening agent is pressed into the hole bottom through the multiple pipes to harden the hole bottom ground and slime and improve the bearing capacity. A method of doing this is known (for example, JP-A No. 2-4724).

[0006]

However, in the above-mentioned conventional load test, in addition to the need for a plurality of reaction force piles, it is necessary to attach a load beam or a jack to the reaction force piles.
Since preparation and removal require time and effort and cost is high, it is the current practice that the certification method is not used to check the bearing capacity or only one of the many methods is checked. Is.

Further, the simple loading test is effective in that it takes less time and labor as compared with the conventional loading test described above, but the expensive jack device cannot be recovered, and the supporting force of all the piles constructed is high. It is still unreasonable in terms of cost to confirm the above, and at present, it is regarded as a promising alternative technique to the conventional loading test. On the other hand, in the conventional method of pushing in the rigid body or the cone block (for example, JP-A 1-223214, JP-A 2-24415, etc.), a large-scale device for pushing in the rigid body or the cone block is required, and before the construction of the pile. Since the piles will be created after going to, there is a risk that the number of steps will increase and the cost will increase.

Further, in the conventional method using a rubber bag or a jack (for example, Japanese Patent Laid-Open Nos. 2-125015 and 3-90706), the number of steps can be reduced, but an expensive device such as a jack is required. There are drawbacks. Furthermore, a conventional method of press-fitting a curing agent with a pipe into the hole bottom ground and slime (for example, Japanese Patent Laid-Open No.
2-4724, etc.), the structure is extremely simple, so it can be expected to be inexpensive, but if there is a sand layer or water vein near the tip ground, the hardened agent injected will flow out to the sand layer or water vein with low pressure. It is considered that the tip ground cannot be strengthened.

Although the above-described method for confirming the supporting force of the pile and the method for increasing the supporting force of the pile each have their own characteristics, the purpose is to still require an expensive device or to achieve only one of them. Many of them cannot be used as a series of methods to confirm the bearing capacity of all or most of the piles constructed and to increase the bearing capacity. Therefore, the method for confirming and increasing the bearing capacity of the cast-in-place pile according to claims 1 to 3 is made in view of the problems of the above-mentioned conventional techniques, and the supporting force of the cast-in-place pile can be easily and inexpensively. By providing a confirmation method and an increasing method, it is possible to confirm the bearing capacity of all or most of the cast-in-place piles to be formed, and at the same time to increase the tip-end supporting force, thereby creating a high-quality cast-in-place pile. And

That is, in the method according to claim 1, a simple and inexpensive device is simply installed in the pile hole before forming the cast-in-place pile, and after the pile is hardened, the support force can be easily confirmed and the tip support force can be confirmed. The purpose is to increase. The method according to claim 2 is
In addition to the purpose of the method according to claim 1, by providing an opening that vertically communicates with the partition plate, at the time of placing concrete,
The purpose is to allow concrete to be placed below the partition plate through this opening, and to prevent cavities and the like from forming below the partition plate.

In addition to the object of the method according to claim 1, the method according to claim 3 is intended to be provided at low cost by using the press-fitting pipe as a part or all of the main bars of the reinforcing bar cage.

[0012]

The present invention is to achieve the above-mentioned object, and the contents thereof will be described below with reference to the embodiments shown in the drawings. The method according to claim 1, wherein the partition plate has substantially the same diameter as the pile hole (H) and is located at a required internal height position thereof.
The tubular auxiliary device (10) provided with (20) is installed at the bottom of the pile hole (H), and the lower end of the press-fitting pipe (40) is exposed above the partition plate (20) of the auxiliary device (10). Then, concrete is placed in the pile hole (H) to form the pile (50), and after the pile (50) is hardened, the press-fitting pipe (4
Curable fluid (60) is pressed in at a required pressure via (0) and the tip of the pile is divided vertically above the partition plate (20) of the auxiliary device (10) by the pressure input, and the pile (50) It is characterized by consolidating the tip ground with the friction of the peripheral surface as a reaction force to increase the supporting force and confirming the supporting force by the pressure input of the fluid (60).

The invention as set forth in claim 2 is characterized in that the partition plate (20) has an opening (21) which communicates vertically. The method according to claim 3 is characterized in that the press-fitting pipe (40) also serves as the main bar (31) of the reinforcing bar cage (30).

[0014]

According to the first aspect of the present invention, the tip of the pile is controlled by the pressure of the fluid (60) above the partition plate (20) in the tubular auxiliary device (10) without requiring an expensive jack or the like. The auxiliary device (10) is divided into upper and lower parts, and the auxiliary device (10) acts as a cylinder, and the upper part (51) of the divided pile tips acts as a piston, and a hardening fluid (60) such as cement mortar is pressed into the gap. Then,
Using the peripheral friction of the pile (50) as a reaction force, the lower part (52) of the pile tip integrated with the auxiliary device (10) descends due to the pressure of the fluid (60), consolidating the tip ground and supporting force. Can increase. Further, when the pressure of the fluid (60) reaches or exceeds the predetermined pressure, it can be estimated that the required tip resistance has been obtained. In other words, the bearing capacity of the pile (50) can be confirmed.

In most cases, the peripheral friction is larger than the tip resistance. Therefore, the tip ground can be compacted within the reaction force of the peripheral friction of the pile (50) to obtain the required tip resistance. However, it is conceivable that the pile (50) itself will be pushed up and the head of the pile (50) will rise while the pressure of the fluid (60) does not reach the predetermined pressure because the pile length is short or the surrounding ground is soft. . In this case, temporarily lift the pile (50) head and the fluid (60)
Calculate the bearing force and settlement amount of the pile (50) by measuring the pressure input and the amount of press fit of the pile (50) and re-evaluate the bearing capacity, or use multiple surrounding piles as reaction force piles to It is advisable to press-in the fluid (60) again until the pressure of 60) reaches a predetermined pressure.

Here, the auxiliary device (10) is made of a material that does not easily deform such as expansion due to a predetermined pressure input of the hardening fluid (60), for example, a tough steel pipe, Its size is such that it can be easily inserted and installed in the pile hole (H),
In other words, it only needs to have a diameter slightly smaller than the pile hole (H), and its length must be greater than the stroke of the upper part (51) of the pile tip that acts as a piston, and it depends on the position of the partition plate (20). It is preferably about 50 to 150 cm. Further, the inner surface of the auxiliary device (10) is required to be smooth in order to slide the upper part (51) of the pile tip part as a piston, and desirably, in advance, in order to facilitate separation from concrete, It is advisable to apply a release agent or resin paint, or attach a thin film resin.

In addition, the partition plate (20) is a fluid (60) at the tip of the pile.
The auxiliary device (10) is provided at a required height position inside the auxiliary device (10) so that the tip of the pile can be easily and horizontally divided without causing vertical cracks or the like when it is broken by the pressure. In other words, the tip of the pile is gradually destroyed by the press-fitting of the fluid (60) from the press-fitting pipe (40), and finally a crack occurs and the top and bottom are divided, but by installing this partition plate (20) The partition plate (20) serves as a starting point of the crack, the crack spreads along the partition plate (20), and the pile tip portion is easily divided into upper and lower parts without waste. Therefore, the partition plate (20)
The material, the shape and the size are arbitrary as long as they can be a starting point for causing a crack in the pile tip portion, but preferably,
It may be formed of a deformable material such as a styrofoam plate or a rubber plate, or may be laminated on a partition plate (20) made of a metal plate. That is, when the fluid (60) is press-fitted, the styrofoam plate or the like is contracted and deformed to form the flow path of the fluid (60), so that the division can be performed more smoothly.

According to a second aspect of the present invention, the partition plate (20) has an opening (21) which vertically communicates like a mesh shape, a cage shape, etc., and the concrete to be placed has the opening. (2
It can pass through 1) so that it can also be placed below the partition plate (20) so that no cavity or the like is formed below the partition plate (20). The method according to claim 3, wherein the press-fitting pipe (40) is a fluid (60).
As long as it can withstand the pressure input of, it can be used regardless of the material, such as metal pipes and vinyl chloride pipes. Especially when a metal tube is used, it can also be used as a part or all of the main bars of the reinforcing bar cage (30).

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the method for confirming and increasing the bearing capacity of a cast-in-place pile according to the present invention will be described below based on the embodiments shown in the drawings. 1 to 4 show a first embodiment of the present invention, and FIG. 1 (a) is a partially cutaway vertical sectional view showing the configuration of an auxiliary device used in the method of the present invention, FIG. 1 (b). Is the plan view,
2 (a) is a partially cutaway vertical cross-sectional view showing the structure of the reinforcing bar cage and the press-fitting pipe, FIG. 2 (b) is the same plan view, FIG. 3 is an explanatory view showing construction of a pile, and FIG. 4 is press-fitting of fluid. It is explanatory drawing which showed the state.

In FIGS. 1 (a) and 1 (b), 10 shows an auxiliary device used in this method, which is a tubular steel pipe having a diameter slightly smaller than the diameter of the pile hole H. The partition plate 20 is horizontally fixed at a required internal height position, for example, near the lower part. Further, just below the partition plate 20, several communication holes 11 communicating with the inside and the outside of the auxiliary device 10 are opened. Figure 2 (a)
Further, in FIG. 2B, 30 is a rebar cage composed of a plurality of longitudinal main muscles 31 and hoop muscles 32, and is formed to have a diameter that can be inserted into the auxiliary device 10. 40 is a press-fitting pipe formed of a metal pipe, a vinyl chloride pipe, or the like, and in this embodiment,
The four press-fitting pipes 40 are arranged along the inner surface of the rebar cage 30 at every 90 degree angle, and the ends thereof are located slightly higher than the tips of the longitudinal main bars 31 of the rebar cage 30 to form the longitudinal main bar 31 of the rebar cage 30 or the hoop. The muscle 32 is tied with a wire or the like so that both are integrated.

Now, as shown in FIG. 3, a pile hole H having a required radius and depth is excavated in the ground G, slime treatment is applied to the bottom of the hole, and a rooting mortar M is placed, and then the auxiliary device 10 is used. Is hung in the pile hole H, and its weight or the weight of the rebar cage 30 to be installed thereafter is used to push it into the root-hardening mortar M for installation. That is, as the root-setting mortar M bites into the lower space of the auxiliary device 10 partitioned by the partition plate 20, muddy water or the like is discharged from the communication hole 11 to the outside of the auxiliary device 10 and the root-setting mortar M in the lower space of the auxiliary device 10. Since they enter without any gap, the auxiliary device 10 can be installed in a state where both are integrated. Then, the rebar cage 30 to which the press-fitting pipe 40 is fixed is hung down, its tip is inserted into the auxiliary device 10 and installed on the partition plate 20, and the tremie pipe T is inserted into the center of the rebar cage 30. Concrete is cast and the required place piles 50 are constructed.

When the pile 50 hardens after the required curing period, a press-fitting pump P is connected to the upper end of the press-fitting pipe 40 as shown in FIG. 4 to set a hardening fluid such as cement mortar.
60 is press-fitted between the lower surface of the concrete solidified in the auxiliary device 10 and the upper surface of the partition plate 20 of the auxiliary device 10, and the two are separated by the pressure input. That is, the tip of the pile should be
Split into and.

At the time of press-fitting the curable fluid 60, when a plurality of press-fitting pipes 40 are used as in this embodiment, initially,
One or two pipes 40 are released, the fluid 60 is press-fitted in the remaining pipes 40, the outflow of the fluid 60 from the released pipes 40 is confirmed, and the opening / closing valve 70 of these pipes 40 is closed, or Alternatively, these pipes 40 may also be connected to the press-fitting pump P to press-fit the curable fluid 60. That is, the air and muddy water in the pipe 40 are expelled from the released pipe 40 so that no cavity or the like is formed in the pile tip.

Then, the inner surface of the upper part of the auxiliary device 10 acts as a cylinder, and the upper part 51 of the divided pile tip part acts as a piston, and the lower part 52 of the pile tip part, that is, the root-setting mortar integrated with the auxiliary device 10. M is lowered by the pressure of fluid 60,
The tip ground can be consolidated to increase the bearing capacity.
At the same time, the tip resistance of the pile 50 can be estimated by the pressure input at that time. Further, the amount of press fit can also estimate the amount of subsidence of the lower portion 52 at the tip of the pile. If it is confirmed that the tip resistance is equal to or greater than the designed resistance value, fluid 60
The press-fitting is stopped, and curing is performed until the press-fitting curable fluid 60 hardens and becomes a part of the tip of the pile.

Although the present embodiment is as described above, if additionally stated, it is easy to peel it off from concrete by applying a release agent or a resin coating or pasting a thin film resin on the inner surface of the upper part of the auxiliary device 10 in advance. It is good to leave it. Further, the partition plate 20 may be formed of a deformable material such as a Styrofoam plate or a rubber plate, or a deformable material such as a Styrofoam plate may be laminated on the partition plate 20 made of a metal plate. In other words, the pressurization of the fluid 60 causes the Styrofoam plate and the like to shrink and deform,
Since the flow path of the fluid 60 is formed, the division can be performed more smoothly.

Further, the press-fitting pipe 40 and the rebar cage 30 can be individually coped with without being integrated. However, by integrating them as in this example, the suspending work can be carried out once and the site Labor saving can be done. On the other hand, FIGS. 5 to 9 show another embodiment of the present invention, and FIG. 5 (a) is a longitudinal sectional view showing a second embodiment of the auxiliary device used in the method of the present invention.
FIG. 6B is a plan view of the same, FIG. 6 is a vertical cross-sectional view showing a third embodiment of the auxiliary device, FIG. 7 is a vertical cross-sectional view showing a fourth embodiment of the auxiliary device, and FIG. 9 is a plan view showing an embodiment, FIG.
[Fig. 8] is a plan view showing a sixth embodiment in which the press-fitting pipe is also used as the longitudinal main bar of the reinforcing bar cage.

In the following description of each embodiment,
The same components as those in the first embodiment described above are designated by the same reference numerals, and detailed description thereof will be omitted. Now, FIG. 5 shows the auxiliary device 10.
2 shows a second embodiment of the partition plate 20 of FIG.
An opening 21 of a size large enough to allow the tremie tube T to be inserted therethrough is formed in the center of the. That is, when the partition plate 20 itself is formed in a donut shape in plan view and the rooting mortar M is not placed at the bottom of the excavated pile hole H, or a cavity is not reliably formed in the lower space of the auxiliary device 10. In order to do so, the tip of the tremie pipe T is inserted from this opening 21 to the lower space of the auxiliary device 10 so that concrete can be poured. In addition, when adopting this embodiment, depending on the situation,
It is also possible to omit the root hardening mortar M.

Similarly, the third embodiment shown in FIG. 6 is the same partition plate.
An opening 21 having a size that allows the tremie tube T to be sufficiently inserted is opened in the central portion of 20, and a large number of small openings 22 are also formed on the other surface of the partition plate 20 to form a knitting pattern. The upper and lower parts are made to be able to communicate with each other as compared with the second embodiment. In addition, in the fourth embodiment shown in FIG. 7, the opening 21 through which the tremie tube is inserted is not provided, but the partition plate 20 is formed in a cage shape, and the upper and lower partition plates 20 can communicate with each other through the long groove-shaped opening 23. It is what

Next, FIG. 8 shows a fifth embodiment of the above-mentioned press-fitting pipe 40. The press-fitting pipe 40 has a U-shaped overall shape, and a plurality of horizontal parts 41 are provided below the press-fitting pipe 40. Outlet 42 is opened. Although not shown, a press-fitting pump is connected to one end of the press-fitting pipe 40 projecting above the ground, and an opening / closing valve is provided at the other end. Thus, when the curable fluid 60 is press-fitted, the fluid 60 is
Pipe from one end of 40 to horizontal part and low pressure 40
Since it reaches the other end through the inside, ensure that the press-fitted pipe 40
It can drive out the air and muddy water inside. After that, similar to the description of the first embodiment, the on-off valve may be closed to increase the pressure input of the fluid 60 and the desired work may be performed.

In the sixth embodiment shown in FIG. 9, the press-fitting pipe 40 is also used as the vertical main bar 31 of the reinforcing bar cage 30, and the structure is simplified and the cost is reduced. Although not shown, a double pipe or the like can be used as the press-fitting pipe.

[0031]

Since the present invention is constituted as described above, it has the following effects. Claim 1
According to the methods described in 1 to 3, it is possible to inexpensively confirm the supporting force of the cast-in-place pile and increase the supporting force of the tip ground by using the tubular auxiliary device provided with the partition plate and the simple device of the press-fitting pipe. effective.

Therefore, when high reliability is required,
By applying the method of the present invention to all or most of the piles constructed on site, the performance of each pile can be guaranteed. It is also possible to review the current cast-in-place piles that tend to be over-designed and design an appropriate cast-in-place pile to provide a high-quality and inexpensive foundation pile. That is, according to the method of claim 1, by simply installing a simple and inexpensive device in the pile hole before forming the cast-in-place pile, after the pile is hardened, the support force can be easily confirmed and the tip support force can be increased. Can be planned.

According to the method of claim 2, since the partition plate is provided with an opening that communicates with the upper and lower sides, concrete can be poured through the opening below the partition plate when concrete is poured. It is possible to prevent a cavity or the like from being formed below the partition plate. According to the method described in claim 3, the press-fitting pipe can be provided at a low cost, particularly by using the press-fitting pipe as a part or all of the main bars of the reinforcing bar cage.

[Brief description of drawings]

FIG. 1 (a) is a partially cutaway vertical sectional view showing a configuration of an auxiliary device according to a first embodiment of the present invention, and FIG. 1 (b) is a plan view thereof.

FIG. 2 (a) is a partially cutaway vertical sectional view showing a structure of a reinforcing bar cage and a press-fitting pipe according to the first embodiment of the present invention.
(b) is a plan view of the same.

FIG. 3 is an explanatory diagram showing construction of a pile according to the first embodiment.

FIG. 4 is an explanatory diagram showing a press-fitted state of a fluid according to the first embodiment.

FIG. 5 (a) is a vertical sectional view showing a second embodiment of an auxiliary device used in the method of the present invention, and FIG. 5 (b) is a plan view thereof.

FIG. 6 (a) is a longitudinal sectional view showing a third embodiment of the auxiliary device used in the method of the present invention.

FIG. 7 is a vertical sectional view showing a fourth embodiment of the auxiliary device used in the method of the present invention.

FIG. 8 is a plan view showing a fifth embodiment of the press-fitting pipe used in the method of the present invention.

FIG. 9 is a plan view showing a sixth embodiment in which the press-fitting pipe used in the method of the present invention is also used as the longitudinal main bar of the reinforcing bar cage.

[Explanation of symbols]

 G Ground H Pile hole M Root consolidation mortar T Tremy pipe P Press-fit pump 10 Auxiliary device 11 Communication hole 20 Partition plate 21 Opening 22 Small opening 23 Long groove-like opening 30 Reinforcing bar basket 31 Vertical main bar 32 Hoop muscle 40 Press-fitting pipe 41 Horizontal part 42 Discharge port 50 Pile 51 Upper part of pile tip 52 Lower part of pile tip 60 Fluid 70 Open / close valve

Claims (3)

[Claims] 1. A tubular auxiliary device having a partition plate which is approximately the same diameter as the pile hole and is provided at a required internal height thereof is installed at the bottom of the pile hole and the lower end of the press-fitting pipe is located above the partition plate of the auxiliary device. Face the pile, pour concrete into the pile hole to create the pile, and after hardening the pile, press hardenable fluid at the required pressure through the press-fitting pipe and partition the tip of the pile with the pressurizing force. It is divided into upper and lower parts above the plate, and the tip ground is consolidated by using the peripheral friction of the pile as a reaction force to increase the bearing capacity, and the bearing capacity is confirmed by the fluid pressure input. How to confirm and increase bearing capacity. 2. The method for confirming and increasing the supporting force of a cast-in-place pile according to claim 1, wherein the partition plate has an opening that communicates vertically. 3. The method for confirming and increasing the bearing capacity of a cast-in-place pile according to claim 1, wherein the press-fitting pipe also serves as a main bar of the reinforcing bar cage.