JP5061079B2 - Ground improvement equipment - Google Patents

Description

The present invention relates to the land board improvement equipment.

  As a ground improvement method, for example, an injection rod having a hexagonal cross section is inserted from the ground surface of the improvement target ground to a target depth in the ground, and the rod radius from the hardening material injection nozzle of the monitor mechanism attached to the tip of the injection rod. The hardened material is continuously ejected at a high pressure in the direction, and a cylindrical or semi-cylindrical improvement body is formed in the ground by pulling up the injection rod while swinging and swirling. There is known a high-pressure jet agitation method in which a reinforcing retaining wall is formed in the ground by forming it continuously in a horizontal direction (see, for example, Patent Documents 1 and 2).

Japanese Patent Publication No. 4-48894 No. 7-48749

However, in the above-described high-pressure jet stirring method in which a cylindrical or semi-cylindrical improved body is continuously formed, the formed diameter of the improved body may be made larger than the designed formed diameter. The following reasons can be cited as the cause of the excessively large diameter of the improved body. (1) If the pulling speed of the injection rod (curing material spraying time by the curing material spray nozzle) is the same, cutting by the curing material jet will occur if the mixing ratio (N value) of viscous soil and sandy soil is different. The distance will be different. Moreover, even if it is the same clay soil and sandy soil, if the hardness (N value) is different, the cutting distance by the hardener jet will be different. The lower the N value, the longer the cutting distance and the larger the formed diameter. (2) The injection rod pull-up speed (hardening material injection time by the hardening material injection nozzle) is determined according to the soil conditions, but if there is a variation in the columnar diagram etc., the injection rod is in a place where the N value is high or the conditions are bad The pulling speed (the injection time of the hardener by the hardener injection nozzle) is determined, so that the soil having a low N value or easily collapses can easily have a large formation diameter.
Thus, when the improvement diameter of the improved body is too large, when the next improved body is formed at a location adjacent to the improved body, the hardener injection nozzle is directed toward the injection rod insertion point of the previous improved body. , That is, the hardened material is injected at a high pressure in the improved body, that is, a column-in-column is generated.

This point will be described in more detail with reference to FIGS. 12 to 15 showing various arrangement patterns of the improved body by the above construction method.
FIG. 12 shows a plurality of improved semi-cylindrical sections (injection rod turning angle θ = 220 °) C1 to C9 on the outer periphery of the foundation (circle P connecting injection rod insertion points O1 to O9). They are circumscribed and arranged in a ring shape so that adjacent improvements are overlapped. Although the construction order is arbitrary, for example, when the improved body C1 is first formed, and then the improved body C2, the improved body C3,... Since the hardened material is injected at high pressure toward the injection rod insertion points O2 and C9 defined in the planned area (area corresponding to the improved bodies C2 and C9), the formation diameter of the improved body C1 is indicated by a virtual line G at this time. If it is too large as described above, there arises a problem that the hardened material is injected at a high pressure in the improved body 1 when the next improved body C2 is formed.

  In FIG. 13, a plurality of improvement bodies D1 to D4 having a columnar cross section are arranged side by side so that parts of the improvement bodies adjacent to each other overlap on a straight line X connecting injection rod insertion points O1 to O4. Even in this case, the construction order is arbitrary. For example, when the improved body D1 is first formed, and then the improved body D2, the improved body D3,... Since the nozzle injects the hardened material at a high pressure toward the injection rod insertion point O2 defined in the region to be formed next (region corresponding to the improved body D2), the formed diameter of the improved body D1 at this time is the phantom line G. If it is too large as shown by, a problem arises in that the hardened material is injected at a high pressure in the improved body D1 when the next improved body D2 is formed.

  In FIG. 14, a plurality of improvement bodies E1 to E5 having a semi-cylindrical cross section are arranged side by side so that parts of the improvement bodies adjacent to each other overlap on a straight line X connecting injection rod insertion points O1 to O5. Even in this case, the construction order is arbitrary. For example, when the improved body E1 is first formed, and then the improved body E2, the improved body E3,. Since the nozzle injects the hardened material at a high pressure toward the injection rod insertion point O2 defined in the region to be formed next (region corresponding to the improved body E2), the formed diameter of the improved body E1 is the phantom line G at this time. If it can be made too large as shown by, a problem arises in that the hardened material is injected at a high pressure in the improved body E1 when the next improved body E2 is formed.

  FIG. 15 shows an improvement rod F1 to F5 having a cross-sectional butterfly column shape by using an injection rod equipped with a pair of hardener injection nozzles in a monitor mechanism and jetting a pair of hardener injection nozzles. The improvement bodies F1 to F5 having a cross-sectional butterfly column shape are arranged side by side so that parts of the adjacent improvement bodies overlap each other on a straight line X connecting the injection rod insertion points O1 to O5. Even in this case, the construction order is arbitrary. For example, when the improved body F1 is first formed, and then the improved body F2, the improved body F3,... Since the nozzle injects the hardened material at a high pressure toward the injection rod insertion point O2 defined in the region to be formed next (region corresponding to the improved body F2), the formed diameter of the improved body F1 is the phantom line G at this time. If it becomes too large as shown by, a problem arises in that the hardened material is injected at a high pressure in the improved body F1 when the next improved body F2 is formed.

When such a problem occurs, there is a problem that a specified formation diameter cannot be obtained, or a tooth missing portion is generated between adjacent improved bodies, resulting in insufficient strength of the reinforcing retaining wall.
In addition, when the injection rod with a hexagonal cross section used for the high-pressure jet stirring method consists of a single pipe and the injection rods made of the single pipe are connected with each other by a coupling, the ultra-high pressure hardener is coupled with the injection rod and the coupling. There is a problem that it is impossible to use an ultra-high pressure jet because it leaks from the connecting portion of the nozzle.

The present invention has been made to solve such problems, and by providing a ground improvement equipment that enables the use of an ultra-high pressure jet, even when the improved body is continuously formed, a specified formation diameter is provided. It is another object of the present invention to provide a ground improvement method that can provide a structure capable of obtaining strength and ensuring strength with few missing parts .

According to the ground improvement equipment of the present invention, the injection rod having a polygonal cross section, a monitor mechanism having a hardening material injection nozzle attached to the tip of the injection rod, and the injection rod are connected as described in claim 1. In the ground improvement equipment provided with a coupling, the coupling protrudes from an intermediate diameter portion formed in a polygonal cross section so as to be fitted in the inner periphery of the polygon of the injection rod, and an intermediate portion of the intermediate diameter portion. The formed large-diameter portion, and one end portion and the other end portion of the medium-diameter portion, respectively, and a small-diameter portion formed in a circular cross section that can be fitted into the polygonal inner peripheral portion of the injection rod, The polygonal inner periphery of the connecting rod end of the injection rod is externally inserted into the polygon outer periphery of the medium diameter portion located at one end of the coupling, and one place in the circumferential direction of the connecting rod end of the injection rod or Attach to screw holes provided in several places The end of the set screw is fitted into a non-penetrating screw receiving bottom hole provided at one end of the coupling corresponding to the screw hole, and the connection side end of the injection rod is A seal ring is interposed between a ring fitting groove provided on the inner periphery and an outer periphery of a small-diameter portion having a circular cross section located at one end of the coupling.

According to the ground improvement equipment of the above configuration, the set screw is screwed into the screw hole provided at one or several places in the circumferential direction of the connecting side end of the injection rod, and the tip of the set screw is connected to one end of the coupling. The one end of the coupling can be secured and secured to the connecting side end of the injection rod by fitting into a non-through screw receiving bottomed hole provided corresponding to the screw hole. The tip of the set screw is fitted into a non-penetrating screw receiving bottomed hole provided at one end of the coupling, and the ring fitting groove and cup provided at the inner periphery of the connecting rod end of the injection rod Since a seal mechanism is used in which a seal ring is interposed between the outer circumference of the small-diameter section with a circular cross section located at one end of the ring, ultrahigh-pressure hardened material leaks from the connecting portion of the injection rod and coupling. Can be prevented.

Since the ground improvement equipment of the present invention uses a pouring rod having a polygonal cross section, the corner of the pouring rod that intersects one surface of the polygon or two adjacent surfaces is defined as the protruding side of the hardener injection nozzle. Thus, even if the curing material spray nozzle is in the ground, the direction of the curing material spray nozzle can be easily confirmed at a glance from the ground. For this reason, an improved body can be created in a location adjacent to the unmodified area so that the injection nozzle of the injection rod specified in the unmodified area is not directed toward the injection rod insertion point. It is possible to create a structure in which a plurality of improved bodies are continuously arranged so as not to cause a column-in-column such as injecting a hardener.

  According to the ground improvement equipment of the present invention, it is possible to prevent the ultrahigh pressure hardened material from leaking out from the connecting portion between the injection rod and the coupling, and therefore, it can be suitably used for the ground improvement method using the ultrahigh pressure jet.

Further, according to the ground improvement equipment of the present invention, the column is formed by forming an improved body at a location adjacent to the unimproved area so that the hardening material injection nozzle does not face the injection rod insertion point defined in the unimproved area.・ Since it is possible to arrange multiple improved bodies in a row so as not to cause in-column, it is possible to obtain a prescribed creation diameter, and to create a construction that can secure strength with little missing parts. To do.

  Preferred embodiments of the present invention will be described below with reference to the drawings. 1 is a side view showing a connection state between an injection rod and a coupling of a ground improvement equipment used in a ground improvement method according to the present invention, FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, and FIG. FIG. 4 is a vertical side view of the monitoring mechanism attached to the tip of the injection rod of the ground improvement equipment, and FIG. 5 is a vertical view of the swivel attached to the head of the injection rod of the ground improvement equipment. 6A is a plan view of the injection rod of the ground improvement equipment, FIG. 6B is a side view of the injection rod of the ground improvement equipment, and FIG. 7A is a coupling of the ground improvement equipment. FIG. 7B is a side view of the coupling of the ground improvement equipment.

  As shown in FIGS. 1 to 5, the ground improvement equipment 1 used in the ground improvement method according to the present invention includes an injection rod 2, a coupling 3 connecting the injection rods 2 and 2, and the head of the injection rod 2. And a monitor mechanism 6 (see FIG. 4) attached to the tip of the injection rod 2.

  As shown in FIG. 5, the swivel 4 attached to the head of the injection rod 2 includes an inlet 7 for super high-pressure drilling water / hardening material that is opened in a part of the peripheral surface of the upper portion thereof, and a central portion from the inlet 7. And a passage 8 communicating with the lower end surface along the axial center.

  As shown in FIG. 4, the monitor mechanism 6 attached to the tip of the injection rod 2 includes a passage 9 that vertically penetrates the central portion, an ultrahigh pressure water nozzle 10 formed at the lower end of the passage 9, and ultrahigh pressure water. A check valve 11 provided at the inlet of the nozzle 10 and a ball valve seat 12 on the upstream side thereof, and a hardening material injection nozzle 13 connected to an intermediate portion of the passage 9 and opening outward in the rod radial direction are provided. By defining the polygonal surface 2a of the injection rod 2 or the angled portion 2b where two adjacent surfaces 2a, 2a intersect as the protruding side of the hardener injection nozzle 13, the hardener injection nozzle 13 can be found in the ground. However, the direction of the curing material injection nozzle 13 can be easily confirmed at a glance from the ground. An excavation bit 14 is provided at the tip of the monitor mechanism 6.

  As shown in FIGS. 6 (a) and 6 (b), the injection rod 2 is formed of a single tube having a cross-sectional shape formed in a polygon such as a hexagon or an octagon, and each of one end and the other end of the injection rod 2 is formed. A screw hole 17 into which a set screw 16 (see FIG. 2) such as a hexagon socket screw is screwed is provided at one or several locations (three locations in the illustrated example) on the outer periphery, and each inner periphery at one end and the other end. Is provided with a ring fitting groove 19 into which a seal ring 18 (see FIG. 3) such as an O-ring is fitted so as to be located at a location different from the screw hole 17.

On the other hand, as shown in FIGS. 7A and 7B, the coupling 3 for connecting the injection rods 2 and 2 is formed in a polygonal cross section so as to be fitted into the polygonal inner periphery of the injection rod 2 . A medium diameter portion 3a, a large diameter portion (flange) 3b having a polygonal cross section that projects from the middle portion of the medium diameter portion 3a, and a plurality of injection rods 2 at one end and the other end of the medium diameter portion 3a, respectively. It is formed in a shape including a small diameter portion 3c formed in a circular cross section that can be fitted into a rectangular inner peripheral portion. A non-penetrating screw receiving bottomed hole corresponding to the screw hole 17 is formed on each outer periphery of the middle diameter portion 3a on one end side and the middle diameter portion 3a on the other end side from the large diameter portion (flange) 3b of the coupling 3 20 is provided.

  Thus, in order to connect the injection rods 2 and 2 with the coupling 3, as shown in FIGS. 1 to 3, one end of the connection side of the injection rod 2 is connected to one end of the large diameter portion (flange) 3 b of the coupling 3. Are inserted into the small-diameter portion 3c and the medium-diameter portion 3a on the side, and a set screw 16 is screwed into a screw hole 17 provided at one end of the injection rod 2 on the connection side, and the tip of the set screw 16 is coupled to the coupling 3 The screw hole 17 and the inside of the coupling 3 are configured to be in a non-communication state by the bottom portion 20a of the screw receiving bottomed hole 20. Ultrahigh pressure drilling water and hardener flowing inside the coupling 3 are prevented from leaking from the screw holes 17. In addition, a seal ring 18 is interposed between the ring fitting groove 19 on the inner periphery of one end of the connection side of the injection rod 2 and the outer periphery of the small-diameter portion 3c at one end of the coupling 3, so that the flow inside the injection rod 2 is increased. Sealed to prevent leakage of high-pressure drilling water and hardener.

  In this case, even when the drilling water and the hardener are injected from the swivel 4 through the injection rod 2, the coupling 3, and the injection rod 2 and from the hardener injection nozzle 13 of the monitor mechanism 6, the drilling water and the hardener are used. The material does not leak from between the screw hole 17 or the inner periphery of the connecting side end of the injection rod 2 and the outer periphery of the small diameter portion 3 c of the coupling 3.

  Next, the ground improvement method of the present invention will be described.

In the ground improvement method, an installation process, a drilling process, an injection test process, a creation process, and a drawing cleaning process are sequentially performed.
In the installation process, the ground improvement device is installed at an arbitrary position on the ground surface of the ground to be improved. The ground improvement device is not shown in the figure, but, as is well known, drilling holes for the injection rod swiveling / lifting drive device, the ground improvement equipment 1 supported by the injection rod turning / lifting drive device, and the injection rod 2 of the ground improvement equipment 1. A curing material ultra-high pressure supply device and an ultra-high pressure water supply device connected to the water / curing material inlet 7 are provided.

In the next drilling process, the vertical hole drilling process and the injection rod insertion process are performed in parallel. That is, the injection rod 2 is vertically set at an arbitrary position on the ground surface of the ground to be improved, and the drilling water supplied to the drilling water / hardening material inlet 7 of the swivel is used as the ultrahigh pressure water nozzle 10 of the monitoring mechanism 6. Then, the injection rod 2 is lowered while being swung downward, and a vertical hole is drilled by the excavation bit 14, and the injection rod 2 is inserted to a predetermined depth in the ground.
When the vertical hole is drilled to the planned depth and the injection rod 2 is inserted to a predetermined depth in the ground, an injection test process is performed.

In the injection test process, first, the steel ball 21 is introduced from the hole 7 water / hardening material inlet 7 of the swivel 4 to close the ball valve seat 12 (see FIG. 4). Thereafter, the injection rod 2 is driven to rotate at a rotational speed set on a trial basis, and at the same time ascended at a rising stroke speed set on a trial basis, an injection test is performed.
In the injection test process, it is determined whether or not cutting has been performed over the range necessary for forming a predetermined cutting area based on the amount of mud discharged from the upper end of the vertical hole, and the optimum turning speed and stroke speed are determined. Is set.
When the optimum turning speed and stroke speed are set in the injection test process, the process proceeds to the creation process.

  In the preparation process, the injection rod 2 is inserted into the vertical hole, and the hardened material is continuously ejected from the hardened material injection nozzle 13 of the monitoring mechanism 6 at the tip of the injection rod 2 in the rod radial direction in the rod radial direction, and the ground is predetermined. In addition, the improved body is cut into the ground by performing a hardening material jetting process in which the cutting area is filled with a hardening material and a swivel lifting process in which the injection rod 2 is swung up while being swung and swung in parallel. Create.

  When the creation of one improved body is completed, a drawing washing step is performed, and the injection rod 2 is drawn to the ground, and the inside of the injection rod 2 is washed with fresh water. Then, it moves to the next creation point (unimproved area), and an improved body is created in the ground in the same procedure. By repeating this process, improvement of the target ground is achieved by creating a plurality of improved bodies.

In the present invention, in the above formation step, an improved body is formed at a location adjacent to the unmodified region so that the curing material injection nozzle 13 does not face the injection rod insertion point defined in the unmodified region. A feature is that an improved body is formed in the unimproved region by inserting and pulling the injection rod 2 into the injection rod insertion point of the unmodified region.
Hereinafter, examples (FIGS. 8 to 11) of the above-described creation step will be described.

  FIG. 8 shows an embodiment of the creation process. In this embodiment, a plurality of substantially semi-cylindrical improvement bodies (substantially half-section with subarcs) circumscribing the outer periphery of the deep foundation (circle P connecting the injection rod insertion points O1 to O9) by the above-described creation process. Cylindrical improvement bodies (for example, injection rod swivel angle θ = 170 °) A1 to A5 and semi-cylindrical improvement bodies (for example, injection rod rotation angle θ = 220 °) B1-B4 Are arranged in a ring shape so that parts of the adjacent improvement bodies overlap each other.The construction order is the improvement bodies A1, A5, A4, A3, A2 first, and then the improvement body. The order of construction of B1, B2, B3, and B4 is arbitrary, and it should be noted here that, for example, among the improved bodies A1, A5, A4, A3, and A2 that are previously formed, the improved body A1 is formed. The hardener injection nozzle 13 is adjacent to the improved body A1. The injection rod 2 is swung and swung, for example, by 170 ° so as not to go to the injection rod insertion points O2 and O9 defined in the improvement regions (regions corresponding to the improvement bodies B1 and B4). As a result, even if the improved body A1 has an excessively large diameter as indicated by the phantom line G, the injection rod 2 is inserted even when the improved bodies B1 and B4 to be formed thereafter are formed. They can be inserted at points O2 and O9.

  FIG. 9 shows another embodiment of the creation process. In this embodiment, an improvement body having a substantially semi-cylindrical cross section having a plurality of dominant arcs on the straight line X connecting the injection rod insertion points O1 to O6 (for example, the swivel angle θ = 220 ° of the injection rod) by the above-described creation process. ) A1 to A6 are arranged side by side so that a part of the adjacent improvements overlap each other. The construction order is the order of improved bodies A1, A2, A3, A4, A5, A6. Even in this case, when the improved body A1 to be formed first is formed, the hardened material injection nozzle 13 is adjacent to the improved body A1 and is next formed in an unimproved area (area corresponding to the improved body A2). The improved body A1 is formed by swinging the injection rod 2 by, for example, 220 ° so as not to go to the prescribed injection rod insertion point O2. As a result, even when the improved body A1 has an excessively large diameter as indicated by the phantom line G, the injection rod 2 is inserted into the injection rod insertion point O2 even when the improved body A2 to be formed thereafter is formed. Can be created.

  FIG. 10 shows still another embodiment of the creation process. In this embodiment, an improved body having a substantially semi-cylindrical cross section having an inferior arc on the straight line X connecting the injection rod insertion points O1 to O5 (for example, the swivel angle θ = 170 ° of the injection rod) A1, A2 and improvement bodies B1 to B3 having a semicircular cross section are alternately arranged and arranged so that a part of the adjacent improvement bodies overlap each other. In the construction order, the improved bodies A1 and A2 are first formed, and then the improved bodies B1 to B3 are formed. Also in this case, for example, when the improved body A1 is formed first, the hardened material injection nozzle 13 is adjacent to the improved body A1, and is subsequently formed in an unmodified area (corresponding to the improved bodies B1 and B2). The injection rod 2 is swung and swung by, for example, 170 ° so as not to go to the injection rod insertion points O1 and O3 defined in the region), and the improved body A1 is formed. As a result, even when the improved body A1 has an excessively large diameter as indicated by the phantom line G, the injection rod 2 is inserted into the injection rod insertion point O1 even when the improved bodies B1 and B2 to be subsequently formed are formed. , O3 can be inserted and created.

  FIG. 11 shows still another embodiment of the creation process. In this embodiment, the injection rod 2 provided with a pair of hardener injection nozzles 13 in the monitor mechanism 6 is used, and the pair of hardener injection nozzles 13 are both jetted to improve the cross-sectional butterfly-shaped improvements A1 to A3, B1. -B2 is formed, and a plurality of adjacent improved bodies A1, B1, A2, B2, and A3 on the straight line X connecting the injection rod insertion points O1 to O5 are overlapped with each other. Are arranged side by side. As for the construction order, improved bodies A1, A2, and A3 are first formed, and then improved bodies B1 and B2 are formed. Also in this case, when the improved body A1 to be formed first is formed, the curing material injection nozzle 13 is defined as an unimproved area (an area corresponding to the improved body B1) which is formed after the improved body A1. The improved body A1 is formed so as not to go to the injection rod insertion point O2. As a result, even when the improved body A1 has an excessively large diameter as indicated by the phantom line G, the injection rod 2 is inserted into the injection rod insertion point O2 even when the improved body B1 to be subsequently formed is formed. It can be created.

  The ground improvement method using an injection rod made of a single pipe according to the present invention is, for example, the protection of the side and bottom of the liner plate shaft used for sewerage work in order to prevent the collapse of spring water and natural ground during excavation. In addition, it can also be applied to work types such as protection of missing parts, prevention of heaving from the bottom board, and prevention of boiling in the construction of shafts such as steel sheet piles and SMW piles. Further, the present invention is not limited to vertical hole excavation, but can be applied to ground improvement for horizontal excavation in the same manner, and can also be applied to improvement target ground such as riverbed and seabed.

  The ground improvement equipment of the above embodiment has an injection rod made of a single tube, but can also be applied to an injection rod made of a double tube or a triple tube.

It is a side view which shows the connection state of the injection rod and coupling of the ground improvement equipment used for the ground improvement method which concerns on this invention. It is the sectional view on the AA line in FIG. It is the BB sectional view taken on the line in FIG. It is a vertical side view of the monitor mechanism attached to the tip of the injection rod of the ground improvement equipment. It is a vertical side view of the swivel attached to the head of the injection rod of the ground improvement equipment. The injection rod of the ground improvement equipment is shown, (a) is a plan view of the injection rod, (b) is a side view of the injection rod. The coupling of the ground improvement equipment is shown, (a) is a plan view of the coupling, (b) is a side view of the coupling. It is a cross-sectional top view which shows an example of the array pattern of the improvement body created by the ground improvement method of this invention. It is a cross-sectional top view which shows the arrangement pattern of the improvement body of another Example. It is a cross-sectional top view which shows the arrangement pattern of the improvement body of another Example. Furthermore, it is a cross-sectional top view which shows the arrangement pattern of the improvement body of another Example. It is a cross-sectional top view which shows the arrangement pattern of the improvement body created by the ground improvement method of the prior art example corresponding to FIG. It is the cross-sectional top view which shows the arrangement pattern of the improvement body created by the ground improvement method of the prior art example corresponding to FIG. It is a cross-sectional top view which shows the arrangement pattern of the improvement body created by the ground improvement method of the prior art example corresponding to FIG. It is a cross-sectional plan view which shows the arrangement pattern of the improvement body created by the ground improvement method of the prior art example corresponding to FIG.

DESCRIPTION OF SYMBOLS 1 Ground improvement equipment 2 Injection rod 3 Coupling 6 Monitor mechanism 13 Hardening material injection nozzle 16 Set screw 17 Screw hole 18 Seal ring 20 Screw receiving bottom hole O1-O9 Injection rod insertion point A1-A5, B1-B4 Improvement body

Claims (1)

In the ground improvement equipment comprising a pouring rod having a polygonal cross section, a monitor mechanism having a hardening material injection nozzle attached to the tip of the pouring rod, and a coupling for connecting the pouring rods.
The coupling has an intermediate diameter portion formed in a polygonal cross section so as to be fitted in the inner periphery of the polygon of the injection rod, a large diameter portion formed overhanging an intermediate portion of the intermediate diameter portion, and the intermediate diameter A small-diameter portion formed in a circular cross section that can be fitted into the polygonal inner peripheral portion of the injection rod, respectively, at one end and the other end of the portion;
A polygonal inner periphery of the connecting side end portion of the injection rod is externally inserted into a polygonal outer periphery of the medium diameter portion located on one end side of the coupling, and one place in the circumferential direction of the connecting side end portion of the injection rod Alternatively, a set screw is screwed into a screw hole provided at several places, and the tip of the set screw is inserted into a non-penetrating screw receiving bottomed hole provided at one end of the coupling corresponding to the screw hole. The seal ring is interposed between the ring fitting groove provided in the inner periphery of the connecting side end portion of the injection rod and the outer periphery of the small-diameter portion having a circular cross section located at one end portion of the coupling. Ground improvement equipment characterized by this.

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