JPH03260216A - Construction of hardened pile - Google Patents

Abstract

PURPOSE:To form a hardened pile under the ground by a method in which a hollow tube housing a flexible cylinder is penetrated into the ground until a given depth is reached, and while the cylinder is tensed and left behind, a hydraulic slurry is injected from the upper part of packer and expanded. CONSTITUTION:A flexible cylinder 1 is tensed in a hollow tube 2 and turned together to excavate the ground, and after it reaches a give depth, anchors are separated from the tube 2 and the cylinder 1 is left behind in a tensed state in the excavated pit of the ground. A casing 22 is attached to the peripheral side of the upper open end 8 of the cylinder 1 and a packer 10 is attached to the inner edge of the open end to close the open end 8 of the cylinder 1. The tip of a pump hose 9 is exactly connected with the end 8 of the cylinder 1 by the packer 10 and a hydraulic slurry is injected into the upper part. A hardened pile 11 having a larger diameter than the outside diameter of the tube 2 can thus be formed under the ground.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to a method for constructing a pile-shaped hardened body used as a foundation for civil engineering and buildings.

(Prior Art) Previous attempts have been made to create pile-shaped hardened bodies in the ground using flexible cylindrical bodies and hydraulic slurry. For example, in JP-A No. 64-36821, a flexible cylindrical body is housed inside a hollow tube so as not to be affected by the surrounding ground, and if the ground is not soft, the hollow tube is inserted while rotating. A flexible cylindrical body was installed in the ground, and the upper open end of the cylindrical body was jointed with an injection hose to inject hydraulic slurry into the interior of the flexible cylindrical body.

(Problem to be Solved by the Invention) However, in this conventional method, in order to form a uniform diameter of the hardened hydraulic slurry in each layer inside the flexible cylindrical body, it is difficult to The flexible cylindrical body must be straightened and re-tensioned, and the hydraulic slurry must be injected with great care, which makes the process complicated, and the diameter or shape of the formed pile-shaped hardened body may vary. There was a fear that the product would not be uniform and would be of poor quality.

This invention was made to eliminate the drawbacks of the prior art, and its purpose is to provide a construction method that can easily and reliably create a high-quality pile-shaped hardened body.

(Means for Solving the Problems) The present invention stores a flexible cylindrical body with an anchor attached to its closed end inside a hollow tube, and also includes attaching the anchor to the tip of the hollow tube. The hollow tube is inserted into the ground with the tip of the hollow tube blocked by the anchor, and after reaching a predetermined depth, the anchor and the hollow tube are separated and the flexible cylindrical body is tensioned into the ground. The hollow tube was left in the same state as before, and only the hollow tube was pulled up.
A casing is attached to the outer periphery of the upper open end of the flexible cylindrical body, a backer is further attached inside the open end, and the upper open end is sealed and fixed by the backer and casing, and then hydraulic slurry is press-fitted from the upper part of the backer. This method of constructing a pile-shaped hardened body is characterized by constructing the hardened body underground while expanding and expanding a flexible cylindrical body.

The present invention will be described in further detail below with reference to embodiments shown in the drawings.

FIG. 1 is a diagram showing an outline of the construction method according to the present invention, FIG. 2 is a diagram showing a flexible cylindrical body 1 housed in a hollow tube 2, and FIG. 3 is a diagram showing a casing 22. and backer 10
FIG.

As shown in FIG. 2, the hollow tube 2 used in this invention has an opening 6 on its distal end surface through which at least the flexible cylindrical body 1 can pass. There are no particular restrictions on the material of the hollow tube 2 as long as it has enough strength to withstand the load when inserted into the ground. In addition, for reasons such as ease of handling, hollow tube 2
It is preferable to have a circular or regular polygonal cross section.

In addition, in the present invention, since the hollow tube 2 housing the flexible cylindrical body 1 is inserted into the ground while rotating, the protruding portion 12 of the anchor 4 set on the distal end surface of the hollow tube 2 as described later.
can be used in place of a bit, but it is particularly preferable to install one or more bits 5 on the outer circumferential surface near the tip of the main body of the hollow tube 2. Further, in order to easily rotate and insert the hollow tube 2 in the ground where sand and gravel are mixed, a spiral wing may be provided around the outer periphery near the tip of the hollow tube 2.

The flexible cylindrical body 1 used in this invention is made of materials such as fibers, plastic films, and metal films, and is formed into a flexible cylindrical body using these materials.
When the hydraulic slurry is press-fitted into the cylindrical body, materials having a tensile strength that can withstand the pressure of the injected hydraulic slurry are widely used. Note that the cylindrical body 1 used in this invention may be flexible as long as it is flexible, but it is particularly preferable to use a product made of fiber that can dehydrate excess water in the hydraulic slurry to be injected from the flexible cylindrical body 1 into the ground. , and generally have high pressure resistance. Most preferred is a flexible cylindrical body made of a woven fabric with even higher pressure resistance, such as a seamless cylindrical tube of tape yarn cloth. The tape yarn cloth tube referred to here is a tape yarn made by slitting a film made of polyolefin resin such as polyethylene, polypropylene, nylon, or other materials, and is formed into a cylindrical shape by weaving etc. using so-called slit yarn. This is what I did.

The tip of the flexible cylindrical body 1 used in this invention is provided with an obturator such as a hose, band, string, wire, etc. so that the hydraulic slurry filled inside the cylindrical body remains inside the cylindrical body.
It is occluded using. Further, near the tip of the flexible cylindrical body 1, an anchor 4 is attached for fixing the flexible cylindrical body 1 in the ground. When the peripheral part of the anchor 4 at least partially protrudes from the outer periphery of the hollow tube, the anchoring function in the ground becomes higher than when the anchor 4 does not protrude. In addition, the flexible cylindrical body 1 is used to connect the flexible cylindrical body 1 and the anchor 4.
A simple method is to pass a part of the vicinity of the tip of the anchor 4 through a bar 13 or a hole provided in the anchor 4, and connect it using the obturator 7.

Note that the anchor 4 attached to the tip of the flexible cylindrical body 1
is an opening to prevent soil particles from entering when inserting the hollow tube 2 into the ground through the gap of the opening for passing the flexible cylindrical body 1 provided on the tip surface of the hollow tube 2. Set part 6 so that it is sealed. A method for sealing in this way is to provide a slit-shaped opening 6 at the tip of the hollow portion with a size commensurate with the size of the anchor 4 so that the anchor 4 can cover the hole. It is preferable to install the anchor 4 so as to cover it with the anchor 4.

Furthermore, when the flexible cylindrical body 1 is stored inside the hollow tube 2, the portion other than the tip including the anchor 4 is inserted into the hollow tube 2, and the slurry is injected later. To facilitate the process, it is necessary to prevent the flexible cylindrical body 1 from twisting, so the cylindrical body 1 must be placed inside the hollow tube 2.
It makes me nervous. As a method of tensioning the cylindrical body,
When storing the cylindrical body 1 inside the hollow tube 2, a steel rod 14 is installed near the upper end of the hollow tube 2, a wire lobe 15 is attached to the center of the steel rod 14, and the other end is attached to a rotating jig. 16, and is tied to the upper open end of the cylindrical body 1. In that state, steel rod 1
By rotating the wire lobes 15 and winding the wire lobes 15, tension can be generated in the cylindrical body 1 and put into a tensioned state. In this way, the steel rod 14 is designed to be rotatable and to engage the anti-reverse claw in order to make it easier to wind up the wire lobe 15 and also to make it easier to unwind the wire lobe 15. It is preferable that the claws be provided so that they can be combined with each other, so that when winding up, the claws prevent reverse rotation, and when rewinding, the claws are disengaged so that unwinding can be performed easily.

As a method for winding up the wire lobes 15, a winding method using a winch is efficient and it is easy to maintain the tension.

By the way, the flexible cylindrical body 1 housed inside the hollow tube 2
In order to avoid twisting, the hollow tube 2 and the cylindrical body 1 are rotated at the same speed during the insertion process.
In the drawing process, it is necessary to prevent rotational force from being transmitted to the cylindrical body 1. For this purpose, it is necessary to provide a rotating jig 16 near the top of the binding portion of the cylindrical body 1 and the wire lobe 15. The rotating jig 16 has an upper end 17 and a lower end 18 that can freely rotate like a universal joint.

In this way, the flexible cylindrical body 1 is rotated under tension inside the hollow tube 2 to excavate the ground, and after reaching a predetermined depth, the anchor is separated from the hollow tube 2 and the flexible cylindrical body 1 is rotated under tension inside the hollow tube 2. If the flexible cylindrical body 1 is left under tension in the excavated hole in the ground, the flexible cylindrical body 1 can be quickly and reliably installed in the ground in a straight and taut state.

In this way, after the hollow tube 2 reaches a predetermined depth, the anchor 4 installed at the distal end of the hollow tube 2 can be separated by using, for example, an anchor 4 that extends to the outer periphery of the hollow tube 2. When the hollow tube 2 is rotated and sunk, the protruding part of the anchor 4 bites into the ground around the tip at a predetermined depth, the anchor 4 is naturally fixed to the ground, and when the hollow tube 2 is pulled up, the anchor 4 is naturally separated.

Furthermore, as a method of pulling up only the hollow tube 2 by leaving the flexible cylindrical body 1 in the excavation hole even after cutting off the anchor 4, it is possible to use the structure shown in FIG. Even when the flexible cylindrical body 1 is wound around the steel rod 14 by the wire lobe 15 above, the flexible cylindrical body 1 is kept under tension, and the flexible cylindrical body 1 separated from the anchor 4 remains under tension. be.

In this state, if you pull up the hollow tube 2 while rotating it, or if you pull it up without rotating it, the tip of the flexible cylindrical body 1 is fixed to the ground by the anchor 4, so the hollow tube 2 The wire lobe 15 wound around the steel rod 14 at the upper part of the tube 2 is unwound according to the amount of wire lobes 14 pulled up, and the flexible cylindrical body 1 is always kept under tension to maintain the hollow tube in a straight state. It can be pulled up.

Note that even if the hollow tube 2 is rotated and pulled up, if the rotating jig 16 is provided as shown in FIG. Only the upper wire rope 15 is unwound while rotating, and the cylindrical body 1 can be held in a straight and taut state without being twisted.

In this way, the hollow tube 2 is lifted above the ground, the wire lobe 15 attached to the flexible cylindrical body 1 that appears near the ground surface at the bottom of the hollow tube 2 is removed, and the flexible tube 2 inserted into the ground is removed. A casing 22 is attached to the outer periphery of the upper open end 8 of the flexible cylindrical body 1.
The packer 10 is attached to the inner circumference of the open end, and the open end 8 of the flexible cylindrical body 1 is sealed and fixed by the backer 10 and the casing 22, and the end of the pump hose 9 and the cylindrical body 1 are connected. After the upper open end 8 is reliably connected with the backer 10, the hydraulic slurry can be injected into the flexible cylindrical body 1 under high pressure by press-fitting the hydraulic slurry from the upper part of the packer 10.

Here, the backer 10 has a cylindrical shape, and a cylindrical elastic body 19 is attached to the outer circumference thereof, and a slurry injection pipe 20 is attached to the inside thereof. Further, the cylindrical elastic body 19 can be expanded and contracted by applying pressure with a fluid such as gas or liquid through a pressurizing tube 21, and the outer circumference of the upper open end 8 of the inserted flexible cylindrical body 1 After installing the casing 22, the backer 10 is installed inside the flexible cylindrical body 1, and the cylindrical elastic body 19 is expanded.
The flexible cylindrical body 1 can be fixed by being pressed against the inner circumference of the casing 22. .

Note that when injecting the hydraulic slurry, a friction force greater than the interfacial friction force between the casing 22 and the cylindrical elastic body 19 may occur, so just to be sure, a flat parr 23 is attached to the injection pipe at the top of the packer 10. It is also possible to install the flat par 23 on a perforated bar 24 attached to the upper part of the casing 22 and fix it with a pin 25. Furthermore, by installing the casing 22 below the ground surface, the stability of the packer 10 is ensured, and even if the flexible cylindrical body 1 expands and expands due to injection of hydraulic slurry, the upper end of the cylindrical body 1 is protected by the casing 22, and it is also possible to prevent damage to the flexible cylindrical body that is likely to occur in this part.

Further, the method of filling the inside of the flexible cylindrical body 1 with hydraulic slurry is to press-fit the hydraulic slurry into the interior of the cylindrical body 1 from the upper open end 8 of the cylindrical body 1 near the ground using, for example, a pump.

In this invention, even if hydraulic slurry is filled under high pressure by press-fitting, it can be carried out without causing injection troubles, so the topography of the hardened body to be created is not affected by the strength of the ground and can be repeatedly carried out. The reproducibility is also good, and the created pile-shaped hardened body has high adhesion to the ground, the reproducibility of that adhesion is good, and its supporting performance is also excellent.

The hydraulic slurry used in this invention may be cement-based, gypsum-based, lime-based, or slurry that can be press-injected.
Although it is possible to use pozzolanic, slag-based, and other materials alone or in combination, it is preferable to use cement-based mortar or concrete from the viewpoint of economy, fluidity, strength characteristics, etc.

In this way, by press-fitting the hydraulic slurry, the flexible cylindrical body 1 is expanded and expanded, and finally, the hollow tube 2
A hardened body 11 having a diameter exceeding the outer diameter of is created underground.

The present invention will be described in more detail below using an example of the present invention. In addition, a comparative example was also used in order to make this invention more clear.

(Example) As shown in Fig. 1, the outer diameter is 190°7mm and the wall thickness is 5mm.
A steel tube with a diameter of 5 mm and a length of 5000 mm is used as the hollow tube 2, and inside it is a flexible cylindrical body 1 made of polypropylene tape yarn with an outer diameter of 300 mm and a length of 5000 mm, that is, the strength of the weft is about 400 kg. / 3 cm and an elongation of about 20% polypropylene chive yarn, and the warp strength is about 300 kg The flexible cylindrical body 1 woven into
The cylindrical body 1 was stored as shown in the figure, the distal end of the cylindrical body 1 was closed with a hose band 7, and an anchor 4 having a portion protruding outward from the hollow tube 2 of the steel pipe portion was attached. Next, a wire rope 15 with a length slightly longer than the length of the hollow steel tube 2 is attached to the upper part of the flexible cylindrical body 1 using a rotating jig 16, and the wire rope 15 is attached to the steel rod 14 using a winch.
The flexible cylindrical body 1 was tightened, and the anchor 4 was placed in the lower part of the hollow tube 2 made of steel to seal the lower part of the hollow tube 2.

Note that the outer circumference of the tip of the hollow tube 2 has a diameter of 30 x 50 x 9 mm.
This hollow tube 2, which had a steel bit attached to it and the flexible cylindrical body 1 housed in the above state, was rotated while drilling a hole in the ground and inserting it.

After reaching a predetermined depth of about 5 m or more, the hollow tube was pulled up while rotating. In this embodiment, the anchor 4 has a portion that protrudes outward from the hollow tube 2 made of steel pipe.
and using the rotating jig 16, the wire lobe 1 is
5 holds the cylindrical body 1 in tension, and the wire lobe 15 is wound around the steel rod 14, so that by simply pulling up the hollow tube 2, the anchor 4 is separated and the flexible tube is The body 1 could be left under tension in the borehole.

Next, as shown in Fig. 3, an outer diameter of 250 mm and a wall thickness of 3
．． A steel casing 22 with a length of 2 m + n and a length of 500 mm is fitted onto the outer periphery of the upper open end 8 of the flexible cylindrical body 1 inserted under tension into the ground, and the steel casing 22 is then inserted into the ground surface. After installing the rubber packer 1
0 into the inner circumference of the upper open end 8 of the flexible cylindrical body 1,
The rubber was expanded with air to complete the installation of the packer 10. Next, the injection hose connected to the mortar pump is connected to the packer, and the pump fills the inside of the flexible cylindrical body 1 with a cement/sand weight ratio of 0.5 and a water/cement weight ratio of 0.6. The mortar used as mortar was press-fitted and injected, and when about 5001 pieces of mortar were injected, the pump was stopped to complete the creation of the hardened body. The injection pressure when the pump was stopped was 10 kg/caf. Later, as a result of excavating and investigating this hardened body, the diameter was approximately 310 mm.
A columnar hardened mortar body with a length of 5000 mm and a length of 5000 mm was formed.

This test was repeated six times, and almost the same columnar pile-shaped hardened bodies were formed all six times.

The ground on which this test was conducted was an almost uniform alluvial cohesive ground with an N value of 0 to 2 up to a depth of 6 m.

In addition to the above-mentioned ground, similar tests were conducted on alluvial cohesive soil with an N value of 2 to 3 up to a depth of 6 m and a sand layer around 2 to 3 m depth, and an N value of 2 to 3 up to a depth of 6 m. When the test was carried out six times on each of two types of diluvial and sticky land, columnar hardened bodies were formed that were almost the same as the hardened bodies that were formed on the homogeneous sticky ground described above.

Next, as a comparative example, first, in the same uniform alluvial cohesive soil as in the example, a flexible cylindrical body having the same material and shape as in the example was inserted into the hollow steel tube used in the example. This cylindrical body was housed in a hollow steel tube without tension and fixation, and the ground was excavated and inserted while rotating the hollow steel tube as in the example. The cylindrical body was inserted into the ground six times in this manner. Of these, in three cases where the hollow steel tube was pulled out while rotating after reaching a predetermined depth, the cylindrical body was twisted when visually observed from above ground at that point. In addition, 1 out of 3 cases in which a hollow steel tube was pulled out without rotating it
In the example, the cylindrical body was similarly twisted.

Next, by the method shown in Fig. 4 without using a casing or the like,
The pump hose 9 and the flexible cylindrical body 1 were connected by a joint 26, and mortar was press-fitted. In three cases, the hollow steel pipe was pulled out while rotating, and in two cases, it was pulled out without rotation. When the amount of mortar injected was approximately 3001, the pressure exceeded 20 kg/cIIl, and the injection hose The mortar fell out of the molded body and leaked, so the creation of the hardened body was terminated.

Later, as a result of an excavation survey, three cases in which hollow steel tubes were pulled out while rotating and two cases in which hollow steel tubes were pulled out without rotation were found to be approximately 2 meters from the ground surface. Although the diameter of each comparative example varied from about 200 mm to 300 mm, the hardened material was columnar in shape, but if the depth was less than that, the mortar would not be filled sufficiently and the material would not be flexible. The cylinder did not swell sufficiently, and in extreme cases no mortar was poured at all.

In addition, similarly to the example, the cylindrical body was inserted into the ground six times in the same manner as in the above-mentioned comparative example in an alluvial clay soil slab and a diluvial clay soil slab in which sandy soil was present. However, these 2
In all three types of ground, the test was carried out under the same conditions as in the comparative example above, except that the hollow pipe in the steel pipe section was pulled out while rotating. This result shows that in each of the six cases, the cylindrical body was twisted, similar to the three comparative examples in which the hollow tube of the steel pipe section was pulled out while rotating.
The shape of the hardened bodies was also incomplete, and mortar was not injected in many cases deeper than 2 to 3 meters from the ground surface.

(Effects of the Invention) The present invention has the following advantages and effects compared to the prior art.

■ The flexible cylindrical body is inserted into the hollow pipe, and the tubular body can be inserted into the ground in one step under tension, making installation easy and quick.

■ The flexible cylindrical body is always under tension both when inserting and withdrawing the hollow tube, so that the cylindrical body remains straight during the subsequent hydraulic slurry injection process, and no force is applied to the cylindrical body. No stress concentration occurs.

■ The flexible cylindrical body is sunk in a straight state at °C, and when hydraulic slurry is injected into the flexible cylindrical body at high pressure, the casing and packer Because the upper open end is sufficiently sealed, a columnar hardened body with the same diameter can be stably obtained even after repeated tests, and the support performance of this columnar hardened body for pile-shaped objects is also stable and excellent. It becomes something. Further, according to the present invention, damage to the flexible cylindrical body naturally does not occur.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the construction procedure of a pile-shaped hardened body according to the present invention, FIG. 1(a) is the excavation and insertion process, FIG. FIG. 1(C) shows the step of press-fitting the hydraulic slurry into the flexible cylindrical body, and FIG. 1(d) is a diagram schematically showing the pile-shaped hardened body after the hydraulic slurry has hardened. FIG. 2(a) is a sectional view showing an example of a flexible cylindrical body stored under tension in a hollow tube according to the present invention, and FIG. 2(a) is a bottom view thereof. Figure 3 (a), Figure 3, etc.)
FIG. 2 is a plan view and a longitudinal sectional view showing an example of press-fitting a hydraulic slurry into a flexible cylindrical body according to the present invention. FIGS. 4(a) and 4(b) are a plan view and a longitudinal sectional view showing a conventional injection process. DESCRIPTION OF SYMBOLS 1...Flexible cylindrical body, 2...Hollow tube, 3...Distal end closure part of flexible cylindrical body, 4...Anchor, 6...Distal end opening of hollow tube Part 8... Upper open end of flexible cylindrical body, 10... Backer 22... Casing. Figure 1

Claims (1)

[Claims] A flexible cylindrical body with an anchor attached to the tip is stored inside the hollow tube, and the anchor is attached to the tip of the hollow tube and the tip of the hollow tube is closed by the anchor. is inserted into the ground, and after reaching a predetermined depth, the anchor and the hollow tube are separated, the flexible cylindrical body remains under tension in the ground, and only the hollow tube is pulled up and the flexible tube is removed. This can be done by attaching a casing to the outer periphery of the open end of the upper part of the cylindrical body, then attaching a packer inside the open end, sealing and fixing the open end of the upper part with the packer and casing, and then press-fitting the hydraulic slurry from the upper part of the packer. A method for constructing a pile-shaped hardened body, which comprises constructing the hardened body underground while expanding and expanding a flexible cylindrical body.