JP2001115440A - Ground improvement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ground improvement method to improve the ground over an extensive range by preparing a plurality of improvement materials without generating any overlapping areas or non-improved areas. SOLUTION: A rod 20 having injection nozzles N1 and N2 is inserted in a bored hole cut in the ground to be improved, the fluid to cut the ground is ejected J1 and J2 from the ejection nozzles, or the ground improvement materials are ejected to cut the ground and mix the ground with the improvement materials, and the rod is pulled upward while rotating the rod. At least a pair of ejection nozzles N1 and N2 are provided on the rod so that the fluid ejected in the jet process forms the crossing jets J1, J2, J1A and J2A. In the jet process, each ejection nozzle is moved in the axial direction V of the rod so that the section of the area to be mixed with the improvement materials is a non-circular closed shape, and the spaces of a pair of nozzles N1, N2, N1A and N2A to eject the crossing jets N1, N2, N1A and N2A are regularly changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground improvement method for improving a ground by forming an improved body in the ground.

[0002]

2. Description of the Related Art As a very effective construction method for such ground improvement, a so-called "jet grout construction method" is well known. This method (hereinafter referred to as “ground improvement method” or “conventional method”) cuts a boring hole in the ground to be improved, inserts a rod with a monitor at the tip into the boring hole, and monitors the ground. A ground improvement material (including) jet is jetted in a horizontal direction from a nozzle provided in the above, and ground cutting and mixing with the improvement material are performed. And ground cutting
While mixing with the improving material, rotate the rod and pull it up to the ground. As a result, it is possible to construct a cylindrical improvement body made of a mixture of the ground and the ground improvement material and having a radial dimension equal to the jet reach distance.

Here, when it is necessary to improve the ground over a relatively wide range, as shown in FIG. 6, by forming a plurality of improved bodies 1, 2, and 3, the conventional technology I have responded. At that time, so that unimproved parts do not occur,
In general, the improved bodies 1, 2, and 3 are partially overlapped with each other (partial areas).

[0006] However, in an area indicated by hatching in FIG. 6 (overlap area), the improved body once formed is again improved by cutting and mixing with a jet. In particular, in the central region indicated by the reference numeral 123, improvement is performed three times in total. Like this
Improving the same area a plurality of times means that the ground improvement material is consumed more and more, which causes an increase in construction cost.

[0005] Further, when the overlap region of the formed improved body is cut by a jet, the improved body is a mixture of ground improvement materials, so that the slurry generated at the time of cutting by the jet is treated as industrial waste. There must be. Here, there is also a problem that the cost of treating industrial waste is increased, which causes an increase in construction cost.

On the other hand, as shown in FIG. 7, the improved bodies 1, 2, 3, and 4 are constructed so as not to overlap with each other, and only the unimproved areas indicated by reference numerals 6 and 7 are subjected to another process. It is also possible to improve with.

However, with the technique shown in FIG. 7, it is very difficult to form the improved products 1, 2, 3, and 4 so that no overlap region occurs. In addition, unimproved area 6,
It is also difficult to construct such that only 7 is improved, and special equipment is required.

[0008]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above-mentioned problems of the prior art, and does not generate the above-mentioned overlapping area, and furthermore, does not improve the unimproved area. It is an object of the present invention to provide a ground improvement method that allows a plurality of improved bodies to be created without causing any occurrence, thereby enabling ground improvement over a wide range.

[0009]

A ground improvement method according to the present invention comprises a step of inserting a rod provided with an injection nozzle into a boring hole cut into the ground to be improved, and a step of cutting the ground from the injection nozzle. A jet jetting step of injecting a fluid or jetting a ground improvement material to cut the ground and mix the improved material, and a step of pulling up while rotating a rod, wherein the fluid jetted in the jet jetting step And at least one pair of the injection nozzles is provided on the rod so that a cross jet is formed. In the jet injection step, a cross-sectional shape of a region where the ground is cut and mixed with the improving material has a non-circular closed shape. As described above, each of the injection nozzles moves in the rod axis direction, and the interval between the pair of nozzles that inject the cross jet is changed regularly.

In implementing the ground improvement method of the present invention, in the jet injection step, a fluid for cutting the ground is injected from a pair of injection nozzles for injecting a cross jet, and an injection nozzle provided on a monitor at the tip of the rod. It is preferable to inject a ground improvement material from above.

Alternatively, in the jetting step, it is preferable that a ground improvement material is injected from a pair of injection nozzles that inject a cross jet, and the ground improvement material functions as a fluid for cutting the ground.

According to the present invention having such a configuration, at least one pair of the jet nozzles is provided on the rod so that the fluid jetted in the jet jet process becomes a cross jet. In the jet jet process, Each of the injection nozzles is configured to move in the rod axis direction so that the interval between a pair of nozzles that inject a cross jet is changed regularly. Here, if the interval between the pair of nozzles that eject the cross jet changes, the horizontal distance between the collision point (intersection) of the cross jet and the nozzle also changes. Then, the horizontal distance between the collision point of the cross jet and the nozzle is equivalent to the radial dimension in the cross section of the region where the ground is cut and mixed with the improving material, and if the radial dimension in the cross section changes, the cross section is changed. Has a non-circular shape. That is, according to the present invention, the cross-sectional shape of the region where the ground is cut and mixed with the improving material can be made a non-circular closed shape.

If an improved body having a closed shape with a non-circular cross section, for example, an improved body having a rectangular cross section is formed,
When the improved body is formed at a plurality of locations, an area (overlap area) that is improved in an overlapping manner does not occur. Therefore, the amount of the ground improvement material used for at least the overlap region is saved. In addition, when cutting the ground by jet injection, it is not necessary to cut the overlapped part, so there is no need to treat the industrial waste generated by cutting the overlapped part, and the industrial waste treatment cost is correspondingly reduced. Can save.

In implementing the present invention, as a mechanism for adjusting the axial V interval between nozzles, a monitor is divided into two parts.
The upper injection nozzle is provided at the upper part of the monitor, the lower injection nozzle is provided at the lower part of the monitor, and the lower part of the monitor is fixed to the outer cylinder. The outer cylinder and the lower part of the monitor can slide relative to each other, but can rotate relative to each other. And a mechanism for supplying or discharging a pressurized fluid to or from the space, by defining a space by the lower surface of the upper part of the monitor, the inner surface of the outer cylinder, and the upper surface of the lower part of the monitor. It is preferable to provide a mechanism for moving the outer cylinder in the axial direction.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 5 and FIGS.

FIG. 1 shows an outline of construction of a ground improvement method according to one embodiment of the present invention. As is apparent from FIG. 1, according to the ground improvement method according to the embodiment of the present invention,
An improved body 10 (area where the ground is cut and mixed with the improved material) having a square cross section is formed. As shown by the dotted line in FIG. 1, even if a plurality of improved bodies 10 are formed,
Since the cross section of 0 is a square, the ground improvement portions do not overlap as in the prior art of FIG. In addition, if the improved bodies having a square cross section are formed so as to be adjacent to each other, there is a problem that unimproved areas (areas 6 and 7 shown by hatching in FIG. 7) remain as in the prior art shown in FIG. Can be eliminated.

In FIG. 1, reference numeral 20 denotes a rod, and a jet J including a ground improvement material is provided from the rod 20.
1, J2 and J3 are injected. Here jets J1 and J
2, J3 will be described later with reference to FIGS. Then, the ground to be improved is cut by the jets J1 and J2, and mixed with the ground improving material by J3. However,
The jets J1 and J2 may be constituted by jets of the ground improvement material, and the cutting of the ground and the mixing with the ground improvement material may be simultaneously performed by the jets J1 and J2.

Next, a technique for forming the improved body 10 having a square cross section will be described with reference to FIGS. First, although not shown, a boring hole is cut in the ground to be improved, and the injection nozzles N1, N2,
The rod 20 provided with N3 (FIG. 2) is inserted. And
Jets J1, J2, J3 are jetted from the jet nozzles N1, N2, N3, respectively.

Here, as described above, the jets J1, J
Numeral 2 denotes a cutting fluid jet for cutting the ground to be improved (for example, a high-pressure water jet or a jet having a composite structure in which a high-pressure water jet is surrounded by a jet of compressed air). Then, in order to create the cross-sectional dimensions, cross-sectional shape, etc. of the improved body to be formed with high accuracy, the jet J
1, J2 constitutes a cross jet capable of controlling the reaching distance with high accuracy. In other words, the nozzle N1,
N2 constitutes a pair of nozzles that eject a cross jet.
In FIG. 2, the symbol P indicates a collision point (intersection) between the cross jets J1 and J2.

On the other hand, the jet J3 is a jet of a ground improvement material, and has an effect of mixing the ground cut by the jets J1 and J2 with the ground improvement material. The jet injection step is performed by the jets J1, J2, and J3 in the example of FIG.

However, as shown in FIG.
0 may be provided with only the nozzles N1 and N2 for jetting the jets J1 and J2 constituting the cross jet, and the jets J1 and J2 may be formed by jets of the ground improvement material. That is, in the embodiment of FIG. 3, the cutting of the ground and the mixing with the ground improving material can be simultaneously performed by the jets J1 and J2.
In the case of FIG. 3, the jet injection step is performed with the jets J1 and J2.

In FIG. 1 to FIG. 5, high-pressure water or the like is used as a fluid constituting the jets J1 and J2 for cutting the ground. Here, jets J1 and J2
May be constituted by a ground improvement material, and the ground may be cut by the ground improvement material.

Next, a mode of cutting the ground to be improved into a non-circular shape (for example, a square shape) will be described with reference to FIGS. 4 and 5, the jet J
Although only J1 and J2 are shown, the invention is not limited to the embodiment of FIG. In both of the embodiments of FIGS. 2 and 3, cutting is performed in a non-circular cross section in the manner shown in FIGS.

In FIG. 4, a rod 20 has an elongated hole 22,
24 are formed. Then, by the mechanism described later with reference to FIGS.
1 moves in the axial direction of the rod 20 (the direction indicated by the arrow V). The injection nozzle N2 is configured to move in the axial direction of the rod 20 (the direction indicated by the arrow V) in the elongated hole 24.

Here, when each of the injection nozzles N1 and N2 moves in the axial direction V in the slots 22 and 24, the jet J1 jetted from the nozzle N1 and the jet J2 jetted from the nozzle N2 intersect each other. (Collision point) It moves synchronously so that it collides at P and forms a cross jet. That is, the jets J1 and J2 shown by solid lines in FIG.
Is ejected (intersections are indicated by a symbol P), and jets J1A and J2A as indicated by dotted lines are ejected (intersections are indicated by a symbol PA). In order to control the excavation distance (indicated by reference numerals L1 and L2 in FIG. 4) with high accuracy, the position of the injection nozzle is determined so as to be always a cross jet.

In FIG. 4, the positions of the nozzles when the cross jets J1 and J2 as shown by solid lines are jetted are indicated by reference numerals N1 and N2, respectively. On the other hand, the positions of the nozzles when the cross jets J1A and J2A as shown by the dotted lines are jetted are indicated by symbols N1A and N2A, respectively. When the cross jets J1 and J2 indicated by solid lines are jetted, the interval in the axial direction V of the nozzles N1 and N2 (the interval between a pair of nozzles that jets the cross jet) is indicated by reference numeral S1, and the reaching distance thereof. Is indicated by reference symbol L1. On the other hand, when the jets J1A and J2A indicated by the dotted lines are jetted, the interval between the nozzles N1A and N2A in the axial direction V (the interval between a pair of nozzles for jetting the cross jet) is denoted by S2.
, And the reaching distance is indicated by a symbol L2.

As is apparent from FIG. 4, the intervals S1 and S2 between the nozzles in the axial direction V correspond to the reaching distances L1 and L2 of the cross jet in a one-to-one correspondence. Therefore, if the distance between the nozzles in the axial direction V is controlled by a mechanism (not shown), the reaching distance of the cross jet, that is, the excavation distance of the ground to be improved, will be controlled.

Insert the rod 20 into a boring hole (not shown) and rotate the rod 20 by means (not shown).
An improved body is created by ejecting the jets J1 and J2 (J3) and pulling them up. By changing the distance between the nozzles in the axial direction V when rotating the rod 20, an improved body having a non-circular closed cross section can be formed. Here, a case where the cross-sectional shape of the formed improved body is, for example, a square will be mainly described with reference to FIGS. 4 and 5.

In FIG. 5, in order to construct an improved body 10 having a square cross section, the ground to be improved has a square cross section (reference numeral 1).
In excavation at 0), the excavation distance from the central rod 20 is the shortest at the center of each side of the square (for example, the point indicated by the intersection PA of the cross jets J1A and J2A in FIG. 5), and the apex of the square ( For example, in FIG. 5, the cross jets J1 and the portion indicated by the intersection P of the JA) are the longest.

Therefore, at the time when the jet is jetted toward the apex of the square by the mechanism for adjusting the axial V interval between the nozzles (FIGS.
The interval V in the axial direction of N2 is a distance indicated by reference numeral S1 in FIG. On the other hand, at the time when the jet is jetted toward the center of each side of the square, the axial V interval between the nozzles (N1A, N2A) may be set to the distance indicated by reference numeral S2 in FIG. Then, in the region between the vertices of the square and the center of each side, the axial V interval between the nozzles may be adjusted according to the distance from the nozzle of the rod 20 to the corresponding portion of the square.

Next, a mechanism for adjusting the axial V interval between the nozzles N1, N2 (N1A, N2A) will be described with reference to FIGS. In FIG. 1 to FIG. 6, the monitor indicated by reference numeral 20 as a whole is, as shown in FIG.
The monitor is divided into an upper monitor 20U and a lower monitor 20L. An injection nozzle N1 located above the monitor upper portion 20U is provided.
L is provided with a lower nozzle N2.

Although not clearly shown, the vicinity of the upper end of the monitor lower portion 20L is integrally fixed to the vicinity of the lower end of the outer cylinder 30 by welding or other methods. The outer cylinder 30 is formed to be hollow, and the upper end 20U of the monitor is inserted into the inner space thereof. The outer cylinder 30 and the upper part 20U of the monitor are spline-coupled (not clearly shown), and are configured to be slidable in the longitudinal direction but not to rotate with each other.

At the upper end of the outer cylinder 30, a swivel type suspender 2
6 is attached, and a wire W is connected to the swivel type hanging member 26 (see reference numeral 27). The wire W is wound or pulled out by a winch or the like (not shown) on the ground side. In addition, the swivel type suspender 26 is provided in order to prevent the wire W from becoming entangled.

As particularly clearly shown in FIGS. 8 and 10, inside the outer cylinder 30, there is a space 38 sandwiched between the upper monitor portion 20U and the lower monitor portion 20L.
In other words, the space 38 is surrounded by the inner surface of the outer cylinder 30, the lower surface of the upper monitor 20U, and the upper surface of the lower monitor 20L.

As shown particularly clearly in FIG. 11, the space 38 has a plurality of transport tubes 34 (3 in the illustrated embodiment).
) Are provided, and one (of them) one transport pipe 34 is provided.
A communication port 36 is opened at a position corresponding to the space 38 of FIG. The transport pipe 34 connects the transport paths 32U, 32U for transporting fluid formed in the upper part 20U of the monitor and the corresponding transport paths 32L, 32L in the lower part 20L of the monitor.

In FIG. 10, reference numeral 40 denotes a seal ring.
It is provided in order to prevent the high-pressure fluid from leaking from a connection point between the transport passage 32L and the lower portion 20L of the monitor.

The space 38 is a space defined by "the lower surface of the upper part of the monitor, the inner surface of the outer cylinder, and the upper surface of the lower part of the monitor", and the transport pipe 34 and the communication port 36 are "the space (38)".
And a high-pressure fluid supplied / discharged from a wire W such as a winch (not shown), a swivel-type suspending device 26, a space 38, and a communication port 36. A mechanism for moving the cylinder in the axial direction. "

Next, the operation of the mechanism shown in FIGS. 8 to 11 will be described. In the case of extending from the contracted state shown in FIG. 9 to the extended state shown in FIG. 8, first, the wire W is paid out from a winch or the like (not shown) on the ground. Here, although not clearly shown, high-pressure water, high-pressure air, and other high-pressure fluid are flowing through the transport pipe 34, and the high-pressure fluid (not shown) is passed through the communication port 36. The space 3
8 flows out. The high-pressure fluid that has flowed out presses the surfaces constituting the space 38 (the inner surface of the outer cylinder 30, the lower surface of the upper monitor 20U, and the upper surface of the lower monitor 20L). Are relatively slid, and the outer cylinder 30 moves downward together with the monitor lower part 20L to be in the extended state shown in FIG. As mentioned above,
Since the wire W is extended, it does not prevent the outer cylinder 30 and the monitor lower portion 20L from moving downward.

As is apparent from a comparison between FIG. 9 and FIG.
If the monitor lower part 20L moves downward, the nozzles N1, N
2 (dimensions indicated by reference numerals S1 and S2 in FIG. 4) becomes longer, and the reaching distance of the intersection of the cross jets becomes longer.

On the other hand, in the case of contracting from the extended state shown in FIG. 8 to the contracted state shown in FIG. 9, if the wire W is rotated in a winding direction by a not-shown winch or the like, the monitor lower part 20L is brought into the state shown in FIG. A force that moves upward is applied. When a force for moving the monitor lower portion 20L upward (together with the outer cylinder 30) acts, an action of reducing the volume of the space 38 occurs, and the high-pressure fluid accumulated in the space 38 is compressed and transported via the communication port 36. It is returned into the tube 34. Then, the monitor lower portion 20L and the outer cylinder 30 return to the contracted position as shown in FIG.

8 and FIG. 9, the lower part 2 of the monitor
When 0L moves upward, the axial dimension of the nozzles N1 and N2 decreases, and the reach of the intersection of the cross jets also decreases. In other words, if the feeding and winding of the wire W are repeated regularly, the "interval between the pair of nozzles for jetting the cross jet changes regularly", and the underground solid having a desired cross-sectional shape is formed. It is created.

Here, the outer cylinder 30 and the monitor 20U are splined and slidable with each other, but do not rotate relative to each other. The outer cylinder 30 and the monitor lower part 20L are integrally connected. Therefore, the nozzle N
Even if the positional relationship in the axial direction between No. 1 and the nozzle N2 is displaced, the positional relationship in the circumferential direction does not change. That is, even if the interval between the nozzles N1 and N2 changes, the jets injected from the nozzles N1 and N2 always collide with each other to form a cross jet, and the excavation distance (reach distance) is accurately controlled.

The jet direction of the cross jet can be accurately controlled by, for example, a boring machine (not shown) installed on the ground side. Therefore, the jet direction of the cross jet and
By appropriately controlling the reaching distance, it is possible to freely change the cross-sectional shape of the underground solid body to be formed.

The mechanism shown in FIGS. 8 to 11 is an example, and a mechanism for adjusting the interval between the nozzles N1 and N2 can be adopted other than the one shown. That is, the illustrated embodiment is merely an example, and is not a description to limit the technical scope of the present invention.

For example, in the illustrated embodiment, the square 1
The corner of 0 is slightly rounded, but the difference between the right-angled corner and the rounded corner is negligibly small in the actual ground improvement method.

In the illustrated embodiment, an improved body having a square cross section is formed. However, an improved body having a non-circular closed cross section other than a square, for example, a rectangular shape, It is also possible to create an improved body having a cross section.

[0047]

The effects of the present invention described above are listed below. (1) When forming an improved body at a plurality of locations, an area (overlap area) that is improved repeatedly does not occur. (2) The amount of ground improvement material used is saved. (3) Since the amount of generated industrial waste including the ground improvement material is reduced, the cost of industrial waste treatment can be saved. (4) It can be implemented with a simple mechanism, the assembly cost and the construction cost are reduced, and the labor required for the ground improvement method can be saved. (5) The cross-sectional shape of the improved body to be formed can be changed by a simple process of changing the axial distance between the nozzles, so that the applicable range is extremely wide.

[Brief description of the drawings]

FIG. 1 is a plan view showing an outline of construction of a ground improvement method according to one embodiment of the present invention.

FIG. 2 is a front view showing an example of a rod used in the present invention.

FIG. 3 is a front view showing another example of the rod used in the present invention.

FIG. 4 is a diagram schematically showing control of a cross jet reaching distance according to the present invention.

FIG. 5 is a plan view showing control of a reaching distance of a cross jet in the present invention.

FIG. 6 is a plan view for explaining a problem of a conventional improvement method.

FIG. 7 is a plan view illustrating a problem in another conventional improvement method.

FIG. 8 is a sectional front view showing an example of a mechanism for adjusting an axial interval between nozzles.

FIG. 9 is a sectional front view showing the mechanism shown in FIG. 8 in a contracted state.

FIG. 10 is an enlarged sectional front view showing a main part of the mechanism shown in FIGS. 8 and 9;

FIG. 11 is a sectional plan view of the mechanism shown in FIGS. 8 to 10;

[Explanation of symbols]

 1, 2, 3, 4, 10 ... improved body 20 ... monitor 22 ... slot J1, J2, J3, J1A, J2A ... jet L, L1, L2 ... jet reach 20 ... Rod N1, N2, N1A, N2A ... Nozzle P, PA ... Collision point (crossing point) of cross jet S1, S2 ... Nozzle interval in axial direction

Claims (3)

[Claims] 1. Inserting a rod provided with an injection nozzle into a boring hole cut in the ground to be improved;
A jet injection step of injecting a fluid for cutting the ground from the injection nozzle or injecting a ground improvement material to mix the ground with the improvement material, and a step of pulling up while rotating the rod, At least one pair of the injection nozzles is provided on the rod so that the fluid injected in the jet injection step becomes a cross jet, and in the jet injection step, a cross-sectional shape of a region where the ground is cut and mixed with the improving material Wherein each of the injection nozzles moves in the axial direction of the rod such that the nozzles have a non-circular closed shape, and the interval between a pair of nozzles for injecting the cross jet is regularly changed. 2. The jet injection step, wherein a fluid for cutting the ground is jetted from a pair of jet nozzles for jetting a cross jet, and a ground improvement material is jetted from an jet nozzle provided at a monitor at the tip of the rod. Item 1. Ground improvement method. 3. The ground improvement method according to claim 1, wherein in the jet injection step, a ground improvement material is injected from a pair of injection nozzles that inject a cross jet, and the ground improvement material acts as a fluid for cutting the ground. .