JP2013127157A - Injection and agitation ground improvement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection and agitation ground improvement method which eliminates the risk of ground collapse due to accumulated air.SOLUTION: The ground G is improved using an injection and agitation ground improvement method which includes steps of: diagonally drilling the ground G using a casing pipe 11; inserting an injection pipe 21 with an injection port 22 of a hardening material J into the casing pipe 11; moving the casing pipe 11 backward and propelling the injection pipe 21 to locate the injection port 22 at a position ahead of the tip edge of the casing pipe 11 by a predetermined length L; and moving the injection pipe 21 and the casing pipe 11 backward while rotating the injection pipe 21 around an axis and injecting the hardening material J, wherein the backward movements of the injection pipe 21 and the casing pipe 11 are performed at the same time, and the injection of the hardening material J is performed so that the injection direction is not directed upward than the horizontal direction.

Description

  The present invention sprays a hardened material, high-pressure fluid, compressed air, etc. in the ground, cuts the ground using this spray pressure, and stirs and mixes the cut earth and hardened material to provide an improved body in the ground. The present invention relates to a jet stirring ground improvement method to be created.

  The ground improvement method that solidifies the ground can be broadly divided into the chemical solution injection method and the stirring and mixing method, and the stirring and mixing method is combined with the mechanical stirring method, the jet stirring method, and the combined stirring that uses both the machine and the injection. It can be roughly divided into construction methods. Among these ground improvement methods, the jet agitation method can solidify soft-viscous ground and silt ground, which are not good at chemical injection methods, and it is constructed differently from the mechanical agitation method and composite agitation method. Since the machine can be as small as a large bore boring machine, various methods such as the CCP method, JSG method (registered trademark), and CJG method have been developed (see, for example, Patent Document 1). .

  Further, according to these injection agitation methods, as shown in FIG. 10 (1), when the injection rod 101 is inserted obliquely with respect to the ground G, the injection from the injection port 102 provided at the tip of the injection rod 101. The curing material J is jetted obliquely upward. Therefore, an air pool (cavity) 111 is formed at the upper end portion of the improved body 110, and the ground 112 in contact with the air pool 111 may collapse. Therefore, for example, as shown in FIG. 10 (2), a proposal has been made to improve the injection port 102 so that the injection direction of the hardened material J does not face obliquely upward (see, for example, Patent Document 2). . According to this proposal, there is no possibility that the air mixed in the improved body 110 stays at the upper end portion of the improved body 110, and as shown by a broken line X, the air passes through the gap (clearance) between the injection rod 101 and the hole inner wall surface 120. It will be discharged smoothly, and it is said that there is no possibility of the ground G collapsing.

  However, since the gap between the injection rod 101 and the hole inner wall surface 120 is narrow, and the hole inner wall surface 120 has irregularities or the like, an air pocket is formed in the gap, and the ground 113 that comes into contact with the air pool is formed. There is a risk of collapse. And even if a part of the ground 113 collapses, the slurry-like earth and sand cannot be discharged. In addition, the air pocket spreads downward and may eventually spread to the upper end of the improved body 110. If the air pool spreads to the upper end of the improved body 110, the ground contacting the air pool may collapse, as in the above-described embodiment.

Japanese Patent Publication No.58-27364 JP-A-11-107267

  The main problem to be solved by the present invention is to provide a jet agitation ground improvement method which does not cause a ground collapse due to air accumulation.

The present invention for solving this problem is as follows.
[Invention of Claim 1]
Drilling the ground diagonally using a casing tube;
Inserting an injection pipe provided with an injection port of a hardener into the casing pipe;
Retreating the casing tube and / or propelling the injection tube to position the injection port forward a predetermined length from the tip edge of the casing tube;
Rotating the injection tube about an axis and retreating the injection tube and the casing tube while injecting the hardened material,
The injection pipe and the casing pipe are retracted at the same time, and the injection of the hardened material is performed so that the injection direction does not face upward from the horizontal direction.
An improved method of ground mixing with jet stirring.

[Invention of Claim 2]
Drilling the ground diagonally using a casing tube;
A step of inserting into the casing tube an injection pipe provided with an injection port of a hardener and an injection port of a high-pressure fluid in this order from the tip side;
Retreating the casing tube and / or propelling the injection tube to position the high-pressure fluid injection port a predetermined length forward from the tip edge of the casing tube;
Rotating the jet pipe around an axis and retreating the jet pipe and the casing pipe while jetting the curing material and the high-pressure fluid, and
The jet pipe and the casing pipe are retracted at the same time, and at least the high-pressure fluid is jetted so that the jet direction is not directed upward from the horizontal direction.
An improved method of ground mixing with jet stirring.

[Invention of Claim 3]
The casing pipe is constituted by adding unit pipes in the axial direction,
Removing the unit tube at the base end and retreating the casing tube by that amount to perform the operation of positioning the injection port forward by a predetermined length from the tip edge of the casing tube.
The injection stirring ground improvement construction method of Claim 1 or Claim 2.

  According to this invention, it becomes the injection stirring ground improvement construction method which does not have a possibility of the ground collapse resulting from an air pool.

It is explanatory drawing which shows the state which installed the drilling pipe. It is explanatory drawing which shows the state drilled with the drilling pipe. It is explanatory drawing which shows the state which pulled out the inner pipe | tube. It is explanatory drawing which shows the state which inserted the injection pipe. It is explanatory drawing which shows the state which protruded the front-end | tip part of the injection pipe. It is explanatory drawing which shows an injection process. It is explanatory drawing which shows the creation state of an improved body. It is explanatory drawing which shows the flow of the air mixed in the improved body. It is an example of injection from an injection pipe. It is an example of creation of a conventional improved body.

Next, modes for carrying out the invention will be described.
In the jet agitation ground improvement method of this embodiment, first, as a preparatory work, construction of a work scaffold or the like is performed as appropriate, and as shown in FIG. Is placed on the ground G. This arrangement is performed so that the tip of the drill tube 10 is located at the drilling start position of the ground G. Further, the drilling pipe 10 is supported by the drilling machine 70 so that the drilling pipe 10 is not perpendicular to the ground G but is inclined to avoid the ground structure 90 or the like. Although this inclination-angle (alpha) is determined by construction conditions and is not specifically limited, For example, 10-80 degrees, Preferably it is 30-60 degrees, More preferably, it can be set to 40-50 degrees. Note that according to the conventional method in which the injection direction is perpendicular to the injection pipe, the limit of the inclination angle α is about 10 °.

  With or before or after the arrangement of the hole drilling machine 70, the support angle adjustment of the hole drilling pipe 10, etc., the installation of a super high pressure pump (not shown), the connection of the piping system, etc. are performed as appropriate. Although not particularly illustrated, the ground G can be dug up at the drilling start position to create a mud pool (empty excavation). The mud accumulated in the mud pool due to drilling, jet stirring, etc. can be sucked using a vacuum vehicle as needed and transported to an industrial waste disposal site or the like for disposal. If the hardened material does not seem to be mixed in the waste mud, it is separated into sediment and liquid using a dehydrator, etc., and the separated liquid is further agglomerated, etc. It can be reused as liquid or pressure liquid.

  Next, as shown in FIG. 2, the ground G is drilled obliquely using the drilling tube 10. The drilling tube 10 of this embodiment is a double tube comprising a casing tube (outer tube) 11 and an inner tube (inner tube) 12 disposed coaxially inside the casing tube 11. Therefore, the ground G is double drilled. However, this drilling is performed using, for example, a single pipe made only of the casing pipe 11 or a multiple pipe more than a triple pipe in which a plurality of other pipes are coaxially arranged in the casing pipe 11. It can also be done.

  In this embodiment, an outer bit 11A made of a ring bit, a metal crown or the like is provided at the tip of the casing tube 11. Further, an inner bit 12 </ b> A made up of a button bit, a cross bit, or the like is provided at the tip of the inner tube 12. On the other hand, the hole drilling machine 70 is provided with a tube body control means such as a percussion drill. The tubular body control means is configured to rotate the casing tube 11 and the inner tube 12 around the axis, to propel and retreat (advance and retreat), and to further strike. Therefore, the ground tube G can be smoothed by propelling the casing tube 11 and the inner tube 12 while applying a rotational force around the shaft center and a striking force in the axial direction to the casing tube 11 and the inner tube 12 by the tube control means. Can be drilled.

  This drilling can be performed while discharging a drilling liquid such as drilling water as necessary. Moreover, the casing pipe | tube 11 and the inner pipe | tube 12 can be comprised by adding a unit pipe | tube suitably according to a drilling length etc.

  When the drilling of the ground G is completed, as shown in FIG. 3, the inner pipe 12 of the casing pipe 11 and the inner pipe 12 embedded in the ground G is casing by using, for example, the above-described tube control means. Pull out from inside the tube 11. Then, as shown in FIG. 4, an injection tube (injection rod) 21 is inserted into the casing tube 11 that is hollowed out by pulling out the inner tube 12.

  A tip portion (monitor) 21A of the injection pipe 21 is provided with an injection port 22 for injecting the hardened material J (see FIG. 6). However, the present invention is not only applied to the jet stirring method in which only the hardened material J is jetted, and as will be described in detail later, the jet stirring method in which compressed air jet, high pressure water jet, or the like is used in combination. Can be applied. Therefore, as the injection tube 21, a known injection tube having a single tube structure, a double tube structure, a multiple tube structure higher than the triple tube structure, or the like can be appropriately used. In the illustrated example, only one injection port 22 for the hardened material J is provided. However, the injection port 22 is provided at a position opposite to the injection tube 21 (a position opposite to 180 degrees). Alternatively, a plurality of two or more may be provided at an appropriate interval in the axial direction.

  When the injection pipe 21 is inserted into the casing pipe 11, the injection pipe 21 is usually followed by retreating the casing pipe 11 and / or propelling the injection pipe 21 as shown in FIG. 5. Projecting forward, and the injection port 22 is positioned in front of the front end edge of the casing tube 11 by a predetermined length L.

  Here, propulsion of the injection pipe 21 can be performed by applying a striking force forward in the axial direction to the injection pipe 21 using, for example, the above-described tube body control means. On the other hand, the casing tube 11 can be retracted, for example, by retracting the casing tube 11 by a predetermined length L using the above-described tube control means or the like.

  However, when the casing pipe 11 is constituted by adding unit pipes in the axial direction as described above, the unit pipe 11B at the base end (most ground side) is removed, as shown in FIG. By reversing the casing pipe 11 constituted by other unit pipes by the length of the unit pipe 11B, the injection port 22 is configured to be positioned in front of the predetermined length L from the tip edge of the casing pipe 11. Is preferred. According to this method, it is possible to accurately control the projecting length of the ejection port 22 to be the predetermined length L.

  In addition, as the various equipment / equipment such as the unit pipe, the pipe body control means, the drilling machine 70, etc., the existing equipment or the modified version is usually used, and the existing equipment / equipment is used. When doing so, the length of the unit tube 11B cannot be adjusted. However, in such a case, the predetermined length L is preferably matched with the length of the unit tube 11B by changing various parameters for determining the predetermined length L described later.

  When the injection port 22 is positioned forward of the predetermined length L from the tip edge of the casing tube 11 as described above, then, as shown in FIG. The hardening material J is injected from the injection port 22 while rotating 21 around the axis. And if the injection pressure of this hardening material J rises to a predetermined pressure, for example to about 20-40 MPa, for example, the injection pipe 21 and the casing pipe | tube 11 will be simultaneously retracted using the pipe body control means etc. which were mentioned above.

  Here, the injection of the hardening material J is performed so that the injection direction does not face upward from the horizontal direction, that is, in the present embodiment in which the inclination angle of the casing tube 11 with respect to the ground G is α °. The injection direction of the material J is performed to be α ° or less. Thereby, as shown in FIG. 7, the upper end portion of the improved body Gx has a conical shape centered on the axis of the injection pipe 21. Therefore, as described above with reference to (2) of FIG. 10, there is no possibility that the air mixed into the improved body Gx stays at the upper end of the improved body Gx, and the ground G collapses due to air pockets (cavities). Is prevented.

  Moreover, in the present embodiment, the injection pipe 21 and the casing pipe 11 are simultaneously retracted in a state where the injection port 22 is located in front of the front end edge of the casing pipe 11 by a predetermined length L, as shown in FIG. In addition, as shown by the broken line X, the air mixed in the improved body Gx is guided to the gap (clearance) 11x between the casing pipe 11 and the injection pipe 21, and is smoothly discharged through the gap 11x. Therefore, there is no possibility that the ground G will collapse due to air accumulation.

  In this regard, as shown in (2) of FIG. 8, when the protruding length of the injection port 22 is Lx shorter than the predetermined length L (Lx <L), the air mixed in the improved body Gx is outside the casing pipe 11. There is a risk that the air flow will stop. And when the flow of air stops, an air pool is formed in the upper end part of the improvement body Gx, and there exists a possibility that the ground G which contact | abuts to this air pool may collapse.

  Therefore, the predetermined length L is, for example, from the viewpoint of guiding the air mixed in the improved body Gx to the gap 11x, for example, the state (geology) of the ground G, the mass / injection pressure / injection amount of the hardened material J, the injection pipe 21 and The receding speed (pulling speed) of the casing pipe 11, the rotational speed of the injection pipe 21, the number of the injection ports 22 and the like can be determined as parameters, for example, 30 to 100 cm, preferably 30 to 50 cm. Regarding the condition of the ground G, for example, N value, gravel content, fine grain content, etc. are parameters for sand ground, and adhesive strength, coarse grain content, plasticity index for viscous ground. The liquidity index is a parameter.

  Further, as the hardener J, for example, cement milk having a water / cement ratio of 100 to 200, or a thickener added to the cement milk can be used. As the thickener, for example, cellulose-based, acrylic-based, natural polymer-based, fibrous mineral-based ones, and the like can be used.

  In the above description, it has been described that the air mixed in the improved body Gx flows through the gap 11x between the casing pipe 11 and the injection pipe 21. However, a part of the air flows outside the casing pipe 11. It is not intended to deny anything. What is necessary is just a state where an air pocket is not formed in the upper end part of the improvement body Gx. In addition, the air mixed in the improved body Gx is not limited to being passed through the gap 11x alone, but the air is normally passed through the gap 11x in a state of being mixed in the slurry-like waste mud. It will be.

  In the above, as schematically shown in (1) of FIG. 9, a mode in which only the hardened material J is injected at a high pressure from the injection port 22 of the injection pipe 21, for example, a CCP-P (Chemical Burning Pile-Pattern) method, CCP Although the present invention has been described with respect to the CCP method such as the -L (Chemical Charging Pile-Large) method and the CCP-S (Chemical Charging Pile-Super) method, the present invention is not limited to this.

  For example, as shown in (2) of FIG. 9, the hardened material J is surrounded by compressed air A and can be applied to a high-pressure jet, for example, a JSG (Jumbo Jet Special Grout) method (registered trademark) or the like. it can. In this embodiment, since the amount of air mixed into the improved body Gx is increased, the effect of the present invention is further exhibited.

  Further, for example, as shown in FIG. 9 (3), the present invention uses an injection pipe 21 in which a lower injection port 22 a of the hardening material J and an upper injection port 22 b of water W as a high-pressure fluid are provided in this order from the front end side. Therefore, it can be applied to the case of ground improvement. In this case, it is necessary that at least the injection direction of the water W as the high-pressure fluid does not face upward from the horizontal direction. In particular, in the example shown in (2) of FIG. It does not face upwards from the direction. However, the hardening material J can also be injected in the direction (vertical direction) orthogonal to the injection pipe 21 from the lower injection port 22a, as shown in (4) of FIG.

  In this case, as shown in FIGS. 9 (3) and (4), the water W can be surrounded by the compressed air A and injected at a high pressure from the upper injection port 22b. Similarly, as shown in FIG. 9 (5), the hardened material J can be surrounded by compressed air A and injected from the lower injection port 22a. Of course, as shown in (6) of FIG. 9, the water W can be injected at high pressure from the upper injection port 22b without being surrounded by compressed air. Furthermore, as shown in (7) of FIG. 9, two lower injection ports 22a are provided at an appropriate interval in the vertical direction, and the cured material J is surrounded by compressed air A and injected from each lower injection port 22a. You can also.

  As described above, in the forms shown in (3) to (7) of FIG. 9, it is assumed that the injection pressure of the curing material J injected from the lower injection port 22a is a normal injection of about 2 to 5 MPa. For example, high pressure injection of about 20 to 40 MPa can be performed.

  The present invention sprays a hardened material, high-pressure fluid, compressed air, etc. in the ground, cuts the ground using this spray pressure, and stirs and mixes the cut earth and hardened material to provide an improved body in the ground. It can be applied as a method for improving the jet stirring ground.

  DESCRIPTION OF SYMBOLS 10 ... Drilling pipe (drilling rod), 11 ... Casing pipe (outer pipe), 11B ... Unit pipe, 11x ... Gap (clearance), 12 ... Inner pipe (inner pipe), 21, 101 ... Injection pipe (injection rod) ), 21A ... injection pipe tip (monitor), 22, 22a, 22b, 102 ... injection port (injection nozzle), 70 ... drilling machine, 90 ... ground structure, 120 ... hole inner wall surface, A ... compressed air, J: Hardened material, G: Ground, Gx: Improved body.

Claims (3)

Drilling the ground diagonally using a casing tube;
Inserting an injection pipe provided with an injection port of a hardener into the casing pipe;
Retreating the casing tube and / or propelling the injection tube to position the injection port forward a predetermined length from the tip edge of the casing tube;
Rotating the injection tube about an axis and retreating the injection tube and the casing tube while injecting the hardened material,
The injection pipe and the casing pipe are retracted at the same time, and the injection of the hardened material is performed so that the injection direction does not face upward from the horizontal direction.
An improved method of ground mixing with jet stirring. Drilling the ground diagonally using a casing tube;
A step of inserting into the casing tube an injection pipe provided with an injection port of a hardener and an injection port of a high-pressure fluid in this order from the tip side;
Retreating the casing tube and / or propelling the injection tube to position the high-pressure fluid injection port a predetermined length forward from the tip edge of the casing tube;
Rotating the jet pipe around an axis and retreating the jet pipe and the casing pipe while jetting the curing material and the high-pressure fluid, and
The jet pipe and the casing pipe are retracted at the same time, and at least the high-pressure fluid is jetted so that the jet direction is not directed upward from the horizontal direction.
An improved method of ground mixing with jet stirring. The casing pipe is constituted by adding unit pipes in the axial direction,
Removing the unit tube at the base end and retreating the casing tube by that amount to perform the operation of positioning the injection port forward by a predetermined length from the tip edge of the casing tube.
The injection stirring ground improvement construction method of Claim 1 or Claim 2.

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