JP4211961B2 - Ground improvement method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ground improvement method for improving the ground by creating an improved body in the ground.
[0002]
[Prior art]
The so-called “jet grout method” is well known as a very effective method for such ground improvement. This method (hereinafter referred to as “ground improvement method” or “conventional method”, etc.) is obtained by cutting a boring hole in the ground to be improved and inserting a rod with a monitor at the tip into the boring hole. A ground improvement material (including) jet is sprayed in a horizontal direction from a nozzle provided in the ground to mix the ground cutting and the improvement material. Then, while mixing with the ground cutting and improving material, the rod is pulled up to the ground side while rotating. Thereby, it is possible to create 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.
[0003]
Here, when it is necessary to improve the ground over a relatively wide range, as shown in FIG. . In that case, it is common to perform construction by overlapping a part (partial region) of the improved bodies 1, 2, and 3 so that no unreformed portion is generated.
[0004]
However, in the region shown with hatching in FIG. 6 (overlapping region), the improved body once formed is cut and mixed with a jet to be improved again. In particular, the central area indicated by reference numeral 123 is improved a total of three times. In this way, improving the same region a plurality of times means that the ground improvement material is consumed more, which causes the construction cost to increase.
[0005]
In addition, when the overlap region of the improved body is cut with a jet, the improved body is a mixture of ground improvement material, so the slurry generated when cutting with the jet must be treated as industrial waste. . Here, there also exists a problem that the cost of processing of industrial waste increases and causes construction costs to increase.
[0006]
On the other hand, as shown in FIG. 7, the constructed improvements 1, 2, 3, and 4 are constructed so as not to overlap, and only the unimproved areas indicated by reference numerals 6 and 7 are improved in a separate process. It is also possible to do.
[0007]
However, with the technique as shown in FIG. 7, it is quite difficult to create the improved bodies 1, 2, 3, and 4 so that no overlap region is generated. In addition, it is difficult to perform construction so that only the unimproved areas 6 and 7 are improved, and special equipment or the like is required.
[0008]
[Problems to be solved by the invention]
The present invention has been proposed in view of the above-described problems of the prior art, and does not generate an overlapping region as described above, and does not generate an unimproved region. Therefore, the purpose is to provide a ground improvement method that enables ground improvement over a wide range.
[0009]
[Means for Solving the Problems]
According to the present invention, in a ground improvement method for excavating a borehole in the ground to be improved and inserting a rod having an injection nozzle into the borehole to create an improved body (10) in the ground, A rod (20) provided with a first spray nozzle (N1), a second spray nozzle (N2), and a third spray nozzle (N3) for spraying the ground improvement material at the tip is prepared. In the first slot (22) provided in the rod (20), the first spray nozzle (N1) is provided, and in the second slot (24), the second spray nozzle (N2) is provided. Each is provided so as to be movable in the axial direction of the rod (20), and the ground is cut by injecting a cross jet from the first and second nozzles (N1, N2) and the ground from the third nozzle (N3). The rod (20) is rotated at the same time as the improvement material is injected. The first and second nozzles (N1, N2) are moved in the elongated holes (22, 24) at that time so that the cross-sectional shape of the region for improving the ground becomes a non-circular closed shape. In addition, the interval between the first and second nozzles (N1, N2) is regularly changed.
[0012]
According to the present invention having such a configuration, at least a pair of the injection nozzles are provided on the rod so that the fluid injected in the jet injection step becomes a cross jet, and in the jet injection step, The distance between a pair of nozzles that each move in the axial direction of the rod and inject a cross jet is configured to change regularly. Here, if the distance between the pair of nozzles that inject the intersecting jet changes, the horizontal distance between the intersection of the intersecting jets (intersection location) and the nozzle also changes. The horizontal distance between the collision point of the intersecting jet and the nozzle corresponds to the radial dimension in the cross section of the region where the ground is cut and mixed with the improvement material, and if the radial dimension in the cross section changes, the cross section The shape is non-circular. In other words, 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 a non-circular closed shape.
[0013]
Then, if an improved body having a non-circular cross section is formed, for example, an improved body having a rectangular cross section, a region that is overlapped and improved (overlap region) when the improved body is formed at a plurality of locations. ) Does not occur. Therefore, the amount of ground improvement material used for at least the overlap region is saved. In addition, when cutting the ground by jet injection, there is no need to cut the overlap part, so there is no need to process the industrial waste generated by cutting the overlap part, and the industrial waste processing cost is correspondingly reduced. Can save.
[0014]
According to the present invention, in the ground improvement method for excavating a borehole in the ground to be improved and inserting a rod into the borehole to create an improved body (10) in the ground, the first injection nozzle (N1 A rod provided with a top monitor (20U) having a second nozzle (N2), a lower monitor (20L) having a second injection nozzle (N2), and an outer cylinder (30) connecting both monitors (20U, 20L) at the tip. The lower monitor (20L) is fixed to the lower part of the outer cylinder (30) and the upper monitor (20U) is splined to the upper part of the outer cylinder (30) and is slidable in the longitudinal direction. Is connected to the swivel-type hanger (26) provided at the upper end of the outer cylinder (30), and the wire (W) is connected to the first and second nozzles (N1, N2). Jetted cross jet At the same time as cutting the ground, the rod is pulled up while rotating, and the lower monitor (20L) is raised by winding the wire (W), or the inner surface of the outer cylinder (30) and the upper monitor (20U) By supplying a high-pressure fluid to a space (38) formed by the lower surface and the upper surface of the lower monitor (20L), the lower monitor (20L) is moved downward together with the outer cylinder (30), thereby the first and first monitors. The interval between the two nozzles (N1, N2) is changed, and the cross-sectional shape of the area where the ground is improved by the cross jet flow from the nozzles is changed to a noncircular closed shape.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 5 and 8 to 11 of the accompanying drawings.
[0016]
FIG. 1: has shown the outline | summary of construction of the ground improvement construction method by one Embodiment of this invention. As can be seen from FIG. 1, according to the ground improvement method according to the embodiment of the present invention, the improved body 10 (region where the ground is cut and mixed with the improved material) is formed. As shown by the dotted line in FIG. 1, even if a plurality of the improved bodies 10 are formed, the improved body 10 has a square cross section, so that the ground improvement points do not overlap as in the prior art of FIG. . Further, if the improved bodies having a square cross section are formed so as to be adjacent to each other, there is a problem that unmodified regions (regions 6 and 7 shown by hatching in FIG. 7) remain as in the prior art shown in FIG. Can be eliminated.
[0017]
In FIG. 1, reference numeral 20 denotes a rod, and jets J <b> 1, J <b> 2 and J <b> 3 containing a ground improvement material are ejected from the rod 20. Here, the jets J1, J2, and J3 will be described later with reference to FIGS. Then, the ground to be improved is cut by jets J1 and J2, and mixed with the ground improvement material by J3. However, it is also possible to form the jets J1 and J2 by a jet of ground improvement material, and simultaneously perform cutting of the ground and mixing with the ground improvement material by the jets J1 and J2.
[0018]
Next, with reference to FIG. 2 to FIG. 5, a technique for creating the improved body 10 having a square cross section will be described.
First, although not shown, a borehole is cut in the ground to be improved, and a rod 20 provided with injection nozzles N1, N2, and N3 (FIG. 2) is inserted into the borehole. Jets J1, J2, and J3 are ejected from the ejection nozzles N1, N2, and N3, respectively.
[0019]
Here, as described above, the jets J1 and J2 are cutting fluid jets 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). ). And in order to produce the cross-sectional dimension, cross-sectional shape, etc. of the improved body to be produced with high accuracy, the jets J1 and J2 constitute a cross jet capable of controlling the reach distance with high accuracy. In other words, the nozzles N1 and N2 constitute a pair of nozzles that inject a cross jet. In FIG. 2, the code | symbol P has shown the collision point (intersection location) of the cross jets J1 and J2.
[0020]
On the other hand, the jet J3 is a jet of ground improvement material, and has an effect of mixing the ground cut by the jets J1 and J2 and the ground improvement material. In the example of FIG. 2, the jet injection process is performed by jets J1, J2, and J3.
[0021]
However, as shown in FIG. 3, the rod 20 may be provided with only the nozzles N1 and N2 for injecting the jets J1 and J2 constituting the intersecting jet, and the jets J1 and J2 may be constituted by the ground improvement material jet. That is, in the embodiment of FIG. 3, it is also possible to simultaneously perform cutting of the ground and mixing with the ground improvement material by the jets J1 and J2. In the case of FIG. 3, the jet injection process is performed by the jets J1 and J2.
[0022]
1-5, as a fluid which comprises the jets J1 and J2 for cutting the ground, for example, high pressure water or the like is used. Here, it is also possible to configure the jets J1 and J2 with a ground improvement material and to cut the ground with the ground improvement material.
[0023]
Next, with reference to FIG. 4 and FIG. 5, the aspect which cuts the ground which should be improved into non-circle (for example, square) is demonstrated. 4 and 5, only the jets J1 and J2 are shown. However, the present invention is not limited to the embodiment shown in FIG. In both of the embodiments shown in FIGS. 2 and 3, it is cut into a non-circular cross section in the manner shown in FIGS.
[0024]
In FIG. 4, long holes 22 and 24 are formed in the rod 20. Then, the injection nozzle N1 moves in the axial direction of the rod 20 (the direction indicated by the arrow V) in the long hole 22 by a mechanism described later with reference to FIGS. And in the long hole 24, it is comprised so that the injection nozzle N2 may move to the axial direction (direction shown by arrow V) of the rod 20. FIG.
[0025]
Here, when each of the injection nozzles N1 and N2 moves in the long holes 22 and 24 in the axial direction V, the jet J1 ejected from the nozzle N1 and the jet J2 ejected from the nozzle N2 intersect (a collision point). It moves synchronously so that it collides with P to form a cross jet. That is, even when jets J1 and J2 as shown by solid lines in FIG. 4 are jetted (intersections are indicated by P), jets J1A and J2A as shown by dotted lines are jetted ( Even if the intersection is indicated by the symbol PA), the position of the injection nozzle is determined so as to be an intersecting jet so that the excavation distance (respectively indicated by the symbols L1 and L2 in FIG. 4) can be controlled with high accuracy. Is done.
[0026]
In FIG. 4, the positions of the nozzles when the intersecting jets J1 and J2 as shown by the solid lines are injected are indicated by reference numerals N1 and N2, respectively. On the other hand, the positions of the nozzles when the intersecting jets J1A and J2A as indicated by the dotted lines are ejected are indicated by reference numerals N1A and N2A, respectively. And the space | interval (space | interval of a pair of nozzle which injects a cross jet) of the nozzles N1 and N2 in case the cross jets J1 and J2 shown by a continuous line are injected is shown by code | symbol S1, The reach | attainment distance Is indicated by the symbol L1. On the other hand, the interval in the axial direction V of the nozzles N1A and N2A when the jets J1A and J2A indicated by the dotted lines are injected (the interval between the pair of nozzles that inject the cross jet) is indicated by S2, and the reach distance is This is indicated by the symbol L2.
[0027]
As apparent from FIG. 4, the distances S1 and S2 between the nozzles in the axial direction V and the arrival distances L1 and L2 of the cross jet flow have a 1: 1 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 is controlled.
[0028]
An improved body is formed by inserting the rod 20 into a boring hole (not shown) and pulling up the jets J1 and J2 (J3) while rotating the rod 20 by means not shown. When the rod 20 is rotated, if the spacing between the nozzles in the axial direction V is changed, a non-circular closed cross-sectional improvement body can be created. Here, the case where the cross-sectional shape of the improved body is made square, for example, will be described mainly with reference to FIGS. 4 and 5.
[0029]
In FIG. 5, when excavating the ground to be improved into a square cross section (reference numeral 10) in order to create the improved body 10 having a square cross section, the excavation distance from the central rod 20 is the center of each side of the square (for example, In FIG. 5, the portion indicated by the intersection PA of the intersecting jets J1A and J2A is the shortest, and the apex portion of the square (for example, the portion indicated by the intersection P of the intersecting jets J1 and JA in FIG. 5) is the longest.
[0030]
Therefore, when the jet is jetted toward the apex of the square by a mechanism for adjusting the axial V spacing between the nozzles (FIGS. 8 to 11: described later), the axial V spacing of the nozzles N1 and N2 is illustrated. 4, the distance indicated by reference sign S <b> 1. 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 of the nozzles (N1A, N2A) may be set to the distance indicated by symbol S2 in FIG. And about the area | region between each vertex of a square and each side center, the axial direction V space | interval between nozzles should just be adjusted corresponding to the distance from the nozzle of the rod 20 to the said part of a square.
[0031]
Next, a mechanism for adjusting the axial V interval between the nozzles N1, N2 (N1A, N2A) will be described with reference to FIGS.
1 to 6, the monitor generally indicated by reference numeral 20 is divided into an upper monitor portion 20U and a lower monitor portion 20L, as shown in FIGS. The upper nozzle 20U is provided with an upper spray nozzle N1, and the lower monitor 20L is provided with a lower nozzle N2.
[0032]
Although not clearly shown, the vicinity of the upper end portion of the monitor lower portion 20L is integrally fixed to the vicinity of the lower end portion of the outer cylinder 30 by welding or other techniques. The outer cylinder 30 is configured to be hollow, and a monitor upper end 20U is inserted into the inner space.
The outer cylinder 30 and the monitor upper part 20U are spline-coupled (not shown clearly) and are slidable in the longitudinal direction, but are configured so as not to rotate with each other.
[0033]
A swivel type hanging tool 26 is attached to the upper end of the outer cylinder 30, and a wire W is connected to the swivel type hanging tool 26 (see reference numeral 27). The wire W is wound or pulled out by a winch (not shown) on the ground side.
The swivel-type hanger 26 is provided to prevent the wire W from being entangled.
[0034]
As particularly clearly shown in FIGS. 8 and 10, a space 38 sandwiched between the monitor upper part 20 </ b> U and the monitor lower part 20 </ b> L exists inside the outer cylinder 30. In other words, the space 38 is surrounded by the inner surface of the outer cylinder 30, the lower surface of the monitor upper portion 20U, and the upper surface of the monitor lower portion 20L.
[0035]
As shown particularly clearly in FIG. 11, the space 38 is provided with a plurality of transport pipes 34 (three in the illustrated embodiment), and the space of one transport pipe 34 (of which) is provided. A communication port 36 is opened at a position corresponding to 38.
The transport pipe 34 connects the transport passages 32U and 32U for fluid transportation formed in the monitor upper portion 20U and the corresponding transport passages 32L and 32L in the monitor lower portion 20L.
[0036]
In FIG. 10, reference numeral 40 denotes a seal ring. The seal ring 40 is provided to prevent high-pressure fluid from leaking from a connection point between the transport pipe 34 and the transport passage 32L in the monitor lower part 20L. It has been.
[0037]
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 connection port 36 “ A high-pressure fluid that constitutes a “supply or discharge mechanism” and is supplied / discharged from a wire W, a swivel-type suspension 26, a space 38, and a connection port 36 such as a winch (not shown) is Mechanism.
[0038]
Next, the operation of the mechanism shown in FIGS. 8 to 11 will be described.
When extending the contracted state shown in FIG. 9 to the extended state shown in FIG. 8, first, the wire W is fed out from a winch or the like on the ground (not shown). Here, although not clearly shown, high-pressure water, high-pressure air, or other high-pressure fluid flows through the transport pipe 34, and the high-pressure fluid (not shown) passes through the communication port 36. It flows out into the space 38. 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 monitor upper part 20U, the upper surface of the monitor lower part 20L), and as a result, the monitor upper part 20U and the inner surface of the outer cylinder 30 Are relatively slid, and the outer cylinder 30 moves downward together with the monitor lower portion 20L to be in the extended state shown in FIG.
As described above, since the wire W is fed out, it does not prevent the outer cylinder 30 and the monitor lower part 20L from moving downward.
[0039]
As apparent from a comparison between FIG. 9 and FIG. 8, when the monitor lower portion 20L moves downward, the axial dimensions of the nozzles N1 and N2 (dimensions indicated by reference numerals S1 and S2 in FIG. 4) become longer and intersect. The reach of the intersection of jets also becomes longer.
[0040]
On the other hand, in the case of contraction from the extended state shown in FIG. 8 to the contracted state shown in FIG. 9, if the wire W is rotated in the winding direction by a winch or the like (not shown), the monitor lower part 20L is moved upward from the state shown in FIG. The force to move to is applied. If the force that moves the monitor lower portion 20L upward (together with the outer cylinder 30) acts, the 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. 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.
[0041]
Comparing FIG. 8 and FIG. 9, when the monitor lower portion 20L moves upward, the axial dimensions of the nozzles N1 and N2 are shortened, and the reach of the intersection of the intersecting jets is also shortened.
In other words, if the feeding and winding of the wire W are repeated regularly, the “interval of the pair of nozzles that inject the cross jets changes regularly”, and the underground solid body having a desired cross-sectional shape is obtained. It is created.
[0042]
Here, the outer cylinder 30 and the monitor 20U are spline-coupled 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 coupled. Therefore, even if the positional relationship in the axial direction between the nozzle N1 and the nozzle N2 is displaced, the circumferential positional relationship does not change. That is, even if the interval between the nozzles N1 and N2 changes, the jets ejected from the nozzles N1 and N2 always collide to form a cross jet, and the excavation distance (reaching distance) is accurately controlled.
[0043]
And the injection direction of a cross jet can be correctly controlled, for example by the boring machine (not shown) etc. which were installed in the ground side.
Therefore, the cross-sectional shape of the underground solid body to be formed can be freely changed by appropriately controlling the jet direction of the cross jet and the reach distance.
[0044]
Note that the mechanisms shown in FIGS. 8 to 11 are merely examples, and a mechanism for adjusting the interval between the nozzles N1 and N2 can be used other than the illustrated one.
That is, the illustrated embodiment is merely an example, and is not intended to limit the technical scope of the present invention.
[0045]
For example, in the illustrated embodiment, the corners of the square 10 are slightly rounded, but the difference between the right corners and the rounded corners is negligible in actual ground improvement construction. Is a small thing.
[0046]
Further, in the illustrated embodiment, an improved body having a square cross section is created, but an improved body having a noncircular closed cross section other than a square, for example, a rectangular cross section, by appropriately controlling the axial interval of the nozzles. It is also possible to create an improved body.
[0047]
【The invention's effect】
The effects of the present invention described above are listed below.
(1) When an improved body is created over a plurality of locations, a region that is improved in a redundant manner (overlap region) does not occur.
(2) The amount of ground improvement material used is saved.
(3) Since the amount of industrial waste including ground improvement materials is reduced, industrial waste disposal costs can be saved.
(4) It can be implemented with a simple mechanism, reducing assembly costs and construction costs, and saving labor spent on the ground improvement method.
(5) Since the cross-sectional shape of the improved body can be changed by a simple process of changing the axial interval of the nozzle, 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 an 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 the cross jet arrival distance in the present invention.
FIG. 5 is a plan view showing control of the cross jet arrival distance in the present invention.
FIG. 6 is a plan view for explaining problems of a conventional improved construction method.
FIG. 7 is a plan view for explaining a problem in another conventional improved construction method.
FIG. 8 is a cross-sectional front view showing an example of a mechanism for adjusting an axial interval between nozzles.
9 is a cross-sectional front view showing the mechanism shown in FIG. 8 during contraction.
FIG. 10 is an enlarged cross-sectional front view showing an enlarged main part of the mechanism shown in FIGS. 8 and 9;
11 is a cross-sectional plan view of the mechanism shown in FIGS. 8 to 10. FIG.
[Explanation of symbols]
1, 2, 3, 4, 10 ... improved body 20 ... monitor 22 ... long holes J1, J2, J3, J1A, J2A ... jet L, L1, L2 ... jet reach 20 ... Rods N1, N2, N1A, N2A ... Nozzle P, PA ... Collision point of intersection jet (intersection)
S1, S2 ... Nozzle spacing in the axial direction

Claims (2)

  In a ground improvement method for excavating a borehole in the ground to be improved and inserting a rod having an injection nozzle into the borehole to create an improved body (10) in the ground, a first method for cutting the ground with cross jets A rod (20) provided with one injection nozzle (N1), a second injection nozzle (N2), and a third injection nozzle (N3) for injecting the ground improvement material at the tip is prepared, and the rod (20) In the first slot (22) provided in the first slot (22), the first spray nozzle (N1) and in the second slot (24) the second spray nozzle (N2) are respectively connected to the rod (20). It is provided so as to be movable in the axial direction, and the ground is cut by injecting a cross jet from the first and second nozzles (N1, N2) and simultaneously with the ground improvement material being injected from the third nozzle (N3). Pull up while rotating the rod (20) At that time, the first and second nozzles (N1, N2) are moved in the long holes (22, 24) so that the cross-sectional shape of the region for improving the ground becomes a non-circular closed shape. And the ground improvement construction method characterized by changing regularly the space | interval of a 2nd nozzle (N1, N2).   In a ground improvement method in which a borehole is excavated in the ground to be improved and a rod is inserted into the borehole to form an improved body (10) in the ground, an upper monitor (20U having a first injection nozzle (N1) is provided. ) And a lower monitor (20L) having a second injection nozzle (N2) and an outer cylinder (30) connecting both monitors (20U, 20L), a rod provided with a tip is prepared. (20L) is fixed to the lower part of the outer cylinder (30), and the upper monitor (20U) is splined to the upper part of the outer cylinder (30) so as to be slidable in the longitudinal direction but not to rotate with each other. The swivel hanger (26) provided at the upper end of the outer cylinder (30) is connected to a wire (W), and a ground jet is ejected from the first and second nozzles (N1, N2). To cut At the same time, the rod is pulled up while rotating, and at that time, the lower monitor (20L) is raised by winding up the wire (W), or the inner surface of the outer cylinder (30), the lower surface of the upper monitor (20U), and the lower monitor (20L) ) To move the lower monitor (20L) together with the outer cylinder (30) downward by supplying a high-pressure fluid to a space (38) formed by the upper surface of the first and second nozzles (N1, N2) A ground improvement construction method characterized in that the cross-sectional shape of a region where the ground is improved by a cross jet from the nozzle is changed to a non-circular closed shape by changing the interval of N2).

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