JP5848939B2 - Jet grout type ground improvement method and jet grout type ground improvement device - Google Patents

Description

  The present invention uses high-pressure jet energy that is not easily affected by ground non-uniformity or soil boundary conditions in construction work such as water blocking walls and reinforced retaining walls, etc. TECHNICAL FIELD The present invention relates to a jet grout type ground improvement method and a ground improvement device that improve ground by mixing and stirring.

  Conventionally, as a jet grout type ground improvement method, for example, a drilling casing is inserted to a target depth in the ground to make a pre-drilling, an injection tube rod is built into the drilling casing, and then the drilling casing is pulled out. The monitor mechanism assembled at the lower part of the spray tube rod is pressed into the ultra high pressure cured material inlet of the swivel attached to the upper part of the spray tube rod and the compressed air from the compressed air inlet of the swivel. The ultra-high pressure cured material is continuously ejected from the material spray nozzle, and the compressed air is continuously sprayed outward from the compressed air spray nozzle around the cured material spray nozzle, and the spray tube rod is rotated 360 degrees or 180 degrees. As shown in FIGS. 9 (a) and 9 (b), by pulling up while rotating or turning at a degree, it is cylindrical or semi- A columnar improved column 21 is formed, and a plurality of improved columns 21 are continuously formed side by side to form an ultra-high pressure injection wall 22 that can be used for a water stop wall, a reinforcing retaining wall, or the like. A ground improvement method is known (for example, refer to Patent Document 1).

Japanese Examined Patent Publication No. 4-48894 (FIGS. 4 and 5)

However, in the above-mentioned jet grout type ground improvement method in which the cylindrical or semi-cylindrical improved column 21 is continuously formed, a water blocking wall, a reinforcing retaining wall, etc. as shown in FIGS. In the ultra-high pressure injection wall 22, the structural strength can be expected only in the width portion indicated by the reference symbol A, and the structural strength is applied to the portion protruding in an arc shape as indicated by the hatched portion B. There is a disadvantage that the material is wasted because it cannot be expected.
Further, since the injection tube rod is pulled up while being rotated or swiveled greatly by 360 degrees or 180 degrees, there is a problem that it takes a long time to construct and the flying distance of the jet liquid is limited.

  The present invention has been made to solve such a problem, and the object of the present invention is the above-described ultra-high-pressure jet of super-high-pressure curing material and compressed air that are continuously injected, In the jet grout type ground improvement method, which is created by cutting and stirring the surrounding ground, the cross-sectional shape of the ultra-high pressure injection wall is made into a plate shape, that is, the walls on both sides in the thickness direction of the ultra-high pressure injection wall are formed flat Yield is good and there is no useless part, and the injection tube rod is not swung at all, or even if it is swung, it can be swollen only slightly, so that the creation time, construction period, jet liquid flying An object is to provide a jet grout type ground improvement method and a ground improvement device capable of extending the distance.

According to the jet grout type ground improvement method of the present invention, at least two excavation casings and a swivel having an ultra-high pressure hardener inlet and a compressed air inlet are assembled to the head, and the tip is monitored. Prepare at least two injection tube rods with a monitor mechanism assembled with two hardener injection nozzles in a point-symmetric arrangement with the tube axis of the monitor tube as the center of symmetry on the outer periphery of the tube And
First, the first drilling casing is inserted to a target depth in the ground to form a first preceding drilling hole, and the first injection pipe rod is installed in the first drilling casing, The second drilling casing is inserted into the first drilling casing to the target depth in the ground along the first drilling casing through the guide device, and the second preceding drilling hole is arranged adjacent to the first preceding drilling hole. The second injection pipe rod is installed in the second excavation casing, and then the second excavation casing is pulled out. Then, the second injection pipe rod is attached to the two pieces of the monitor pipe. The ultra high pressure hardened material from the hardener jet nozzles and the compressed air from the compressed air jet nozzles around the hardener jet nozzles to the alignment direction of the first and second preceding holes, respectively. Continuous in crossing direction By pulling up while spraying, the ground is cut and stirred by the high-pressure hardened material continuously jetted and the high-pressure jet of compressed air to form a plate-shaped ultrahigh-pressure jet wall. After pulling out the first excavation casing, the first injection tube rod is supplied with the super high pressure cured material from the two cured material injection nozzles of the monitor tube, and compressed air is supplied from the compressed air injection nozzles around each of the cured material injection nozzles. And the ultra-high pressure curing material that is continuously ejected by continuously ejecting the material from the monitor tube of the second ejection tube rod and the parallel injection direction of the compressed air. And the ground is cut and agitated with a high-pressure jet of compressed air, and a super-high pressure injection wall having a plate-like cross-sectional shape is laminated in the thickness direction of the ultra-high pressure injection wall. Is shall.

According to the structure of the jet grout type ground improvement method, the first sheet has a plate-shaped ultrahigh pressure injection wall, and then the second sheet has a plate-shaped ultrahigh pressure injection wall. By laminating in the thickness direction of the first ultra-high pressure injection wall, at least two sheets of the cross-sectional shape are integrally laminated in the thickness direction. The ultra-high pressure injection wall can ensure a predetermined wall thickness, but the walls on both sides in the thickness direction of the ultra-high pressure injection wall can be formed flat, so that the entire cross-sectional shape of the ultra-high pressure injection wall can be reduced to earth pressure or water pressure. It can be used as a structural proof force that can resist external forces, eliminating wasted parts.
In addition, when constructing such a plate-shaped ultra-high pressure injection wall, the injection tube rod is pulled up while swinging and swinging at a slight swinging swivel angle even if it is swung in a non-turning state. Therefore, it is possible to construct the injection tube rod in a significantly shorter time than the conventional construction time required for pulling up the jet tube rod while rotating or turning it by 360 degrees or 180 degrees, and extending the flying distance of the ultra high pressure hardened material. Will be able to.

According to a jet grout type ground improvement device of the present invention, a first excavation casing which is inserted to a target depth in the ground to form a first preceding drilling hole, A swivel having a high-pressure hardener inlet and a compressed air inlet is assembled, and two hardener injection nozzles having a point-symmetrical arrangement with the tube axis of the monitor pipe as the center of symmetry are provided on the outer periphery of the monitor pipe at the tip. The first injection pipe rod built into the first excavation casing and the second leading drilling hole by inserting it to the target depth in the ground. A second excavation casing formed in parallel adjacent to the preceding drilling hole, and the first excavation casing and the second excavation casing so as to guide the second excavation casing along the first excavation casing in parallel. Drilling casing A guide device adapted to be carried into the ground by sliding movement provided, along the first run of the drilling casing with the insertion of the two first drilling casing into the ground during the 1 A second injection tube rod constructed in the same configuration as the first injection tube rod and built in the second excavation casing, and formed by pulling up the second injection tube rod The first cross-sectional shape of the plate is a plate-like ultra-high pressure injection wall, and the second cross-sectional shape of the plate-shaped ultra-high-pressure injection wall formed by pulling up the first injection tube rod has a thickness. By laminating in the direction, at least two ultrahigh pressure injection walls having a plate-like cross-sectional shape are integrally laminated in the thickness direction .

According to the configuration of the jet grout type ground improvement device, first, after pulling out the second excavation casing, the second injection pipe rod is connected to the super high pressure hardening material from the two hardening material injection nozzles of the monitor pipe, Pulling up the compressed air from the compressed air injection nozzles around each of the hardener injection nozzles while continuously injecting the compressed air in the direction intersecting the direction of alignment of the first and second preceding holes. Thus, an ultra-high pressure injection wall having a plate-like cross-sectional shape on the first sheet can be formed. Next, after the first drilling casing is pulled out, the first injection tube rod is connected to the two monitor tubes. Ultra-high pressure curing material from the curing material spray nozzle, compressed air from the compressed air spray nozzle around each curing material spray nozzle, and ultra-high pressure curing material and pressure from the monitor tube of the second spray tube rod, respectively. By pulling Ru while continuously injected injection direction parallel to the direction of the air, the second sheet of cross-sectional shape stacked plate-like ultra-high-pressure injection wall in the thickness direction of the first sheet of ultra high-pressure injection wall Therefore, at least two ultrahigh pressure injection walls having a plate-like cross-sectional shape can be integrally laminated in the thickness direction. Therefore, the laminated and integrated ultra-high pressure injection wall can ensure a predetermined wall thickness, and the wall surfaces on both sides in the thickness direction of the ultra-high pressure injection wall can be formed flat. You can expect proof stress and there will be no useless parts.
Further, when constructing such a plate-shaped ultra-high pressure injection wall, the injection tube rod is pulled up in a non-rotating state or while being driven to swing and swing at a slight swing angle even if swung. That's enough, and it can be built in a much shorter time than the conventional construction time required to pull up the jet tube rod while rotating or turning it by 360 degrees or 180 degrees, and the flying distance of the ultra high pressure hardened material can be extended. Will be able to.

  The jet grout type ground improvement device according to claim 2 is characterized in that, as described in claim 3, the guide device can be slidably fitted to the first excavation casing and the second excavation casing, respectively. A configuration in which the cylinders are arranged in the shape of glasses and connected by a connecting member can be employed. According to this, when the second drilling casing is inserted into the ground, it can be stably and reliably slid along the first drilling casing in parallel, and the first leading hole and the second leading Drilling holes can be formed in parallel.

  According to the jet grout type ground improvement method and ground improvement device of the present invention, the yield is good and there is no useless part, and the creation time, the construction period can be shortened, and the flying distance of the ultra high pressure hardened material can be increased. There is an advantage.

(A) is process drawing of the 1st preceding drilling hole in the work process by the jet grout type ground improvement construction method of the present invention, and (b) is a process drawing of the construction of the first injection pipe rod. (A) is process drawing of the 2nd preceding drilling hole in the work process by the jet grout type ground improvement construction method of the present invention, and (b) is a process drawing of the construction of the second injection pipe rod. FIG. 2A is a view showing the construction process of the first ultrahigh pressure injection wall as viewed from the arrow E in FIG. 2B, and FIG. 2B is a view from the arrow E in FIG. It is a drawing process figure of the main injection pipe rod. (A) is a longitudinal sectional view of the monitoring mechanism of the injection tube rod used in the jet grout type ground improvement method of the present invention, (b) is a sectional view taken along the line CC in FIG. 4 (a), and (c) is a modified embodiment. It is sectional drawing which shows an example corresponding to FIG.4 (b). (A) is a top view of the guide apparatus used for the jet grout type ground improvement method of this invention, (b) is the DD sectional view taken on the line in Fig.5 (a). It is a longitudinal cross-sectional view which shows the drilling condition of the 2nd preceding drilling process in the work process by the jet grout type ground improvement construction method of this invention. (A) is a schematic cross-sectional view of the injection pipe rod used for the jet grout type ground improvement method of this invention, (b) is a top view of the steadying member of an injection pipe rod. It is a cross-sectional view which shows the injection preparation condition of the 1st ultra-high pressure injection wall and the 2nd ultra-high pressure injection wall in the work process by the jet grout type ground improvement construction method of this invention. (A) (b) is a cross-sectional view of a water stop wall and a reinforced retaining wall obtained by a conventional jet grout type ground improvement method.

  A preferred embodiment of the present invention will be described with reference to the drawings.

  An embodiment of the jet grout type ground improvement method of the present invention will be described below in the order of steps with reference to FIGS.

(1) Preliminary drilling process by first drilling casing As shown in FIG. 1 (a), a boring machine M is installed on the ground, and the first preceding drilling hole H1 by the first drilling casing 1 is made of water or Perform to the desired drilling depth while spouting bentonite mud. That is, water or bentonite mud is supplied to the inlet 2a of the swivel 2 connected to the upper end of the excavation casing 1, and the water or bentonite mud is discharged from the lower tip conduit 1a equipped with the metal crown 3 of the excavation casing 1, The excavation casing 1 is lowered while being swung and drilled with the metal crown 3 to insert the excavation casing 1 to a predetermined depth in the ground.

(2) Step of erection of first injection tube rod Next, as shown in FIG. 1B, the first injection tube rod 4 is erected to a predetermined depth in the first excavation casing 1.
The injection tube rod 4 used here is a double tube rod, and as shown in FIG. 1 (b), a swivel 5 having an ultrahigh pressure hardener inlet 5a and a compressed air inlet 5b is connected to the upper end thereof. The monitor mechanism 7 as shown in FIG. 4 (a), (b) or (c) is connected to the lower end. The monitor mechanism 7 has a double pipe structure having a jet passage 7a and a compressed air passage 7b. The upper end portion of the jet passage 7a is an ultrahigh-pressure hardened material inlet 5a of the swivel 5, and the upper end portion of the compressed air passage 7b is the above-mentioned portion. The compressed air inlet 5b of the swivel 5 is in communication with each other, and two hardener injection nozzles 7c are provided at the lower end of the jet passage 7a, and a compressed air injection nozzle 7d is provided at the lower end of the compressed air passage 7b. . The two hardener injection nozzles 7 c are provided on the outer periphery of the monitor tube 8 of the monitor mechanism 7 so as to have a point-symmetric arrangement relationship with the tube axis O of the monitor tube 8 as the center of symmetry. The compressed air injection nozzle 7d is formed so as to eject compressed air from the periphery of the curing material injection nozzle 7c.

As shown in FIG. 7 (a), the first injection tube rod 4 is formed in a non-circular cross section by forming a flat surface 4f in the opposite part of the outer peripheral surface, and the two curing material injection nozzles 7c are By arranging so as to correspond to the flat surface 4f, the injection direction of the ultra-high pressure cured material from the two cured material spray nozzles 7c is the ground even if the two cured material spray nozzles 7c are in the ground. It is easy to check at a glance. When the injection tube rod 4 is formed in such a non-circular cross-sectional shape, it tends to be shaken. Therefore, as a measure to prevent the steadying, a rectangular frame shape as shown in FIG. The assembled anti-sway member 9 is installed, and the injection tube rod 4 is inserted into the rectangular hole 9a of the anti-sway member 9 to prevent the rod 4 from steadying.
After the first injection tube rod 4 is inserted, the upper end of the opening of the first excavation casing 1 is closed with the casing lid 10 as shown in FIG.

(3) Pre-drilling step with second excavation casing After the completion of the first pre-drilling hole H1, the boring machine M is moved and the second excavation is performed as shown in FIGS. In the casing 11, the second preceding drilling hole H <b> 2 is carried out in the same manner as the first preceding drilling hole H <b> 1 to the target drilling depth while jetting water or bentonite mud. At this time, it should be noted that the second excavation casing 11 and the second excavation casing 1 and the second excavation casing 11 can be inserted into the ground in parallel with the first excavation casing 1 as shown in FIG. A guide device 12 is provided between the excavation casings 11, and the second excavation casing 11 is inserted through the guide device 12 to a predetermined depth in the ground in parallel with the first excavation casing 1. The hole H2 is constructed adjacent to the first preceding hole H1 in parallel.

  As the guide device 12, for example, as shown in FIGS. 5A and 5B, two short cylinders 12b that can be slidably fitted to the first excavation casing 1 and the second excavation casing 11, respectively. 12a is arranged in the shape of glasses and connected by a connecting member 12c. In use, as shown in FIG. 6, one short cylinder 12a is inserted in advance freely between the metal crown 3 at the tip of the second excavation casing 11 and the guide device presser 13 inserted and fixed above this. When the second excavation casing 11 is inserted into the ground, the other short cylinder 12b is inserted into the first excavation casing 1 and the second excavation casing 11 is inserted into the ground. The cylinder 12b slides along the first excavation casing 1. As the guide device 12, as described above, the two short cylinders 12b and 12a that can be slidably fitted to the first excavation casing 1 and the second excavation casing 11 are arranged in a glasses shape and connected by a connecting member 12c. As a result, when the second excavation casing 11 is inserted into the ground, the first excavation casing 11 can be stably and reliably slid along the first excavation casing 1 in a stable manner. The hole H1 and the second preceding drilled hole H2 can be formed in parallel. However, the guide device 12 is not necessarily limited to such a structure. In addition, although not illustrated, for example, a guide groove is provided in one of the first excavation casing 1 or the second excavation casing 11. It is also possible that the other second excavation casing 11 or the first excavation casing 1 is provided with a slide protrusion or slide ridge that is slidable in the guide groove.

(4) Second injection tube rod erection step After the completion of the second preceding drilling hole H2, as shown in FIG. 2 (b), the first drilling casing 1 is placed in the second drilling casing 11. The second injection tube rod 14 having the same structure as that is built up to a predetermined depth.

(5) Drawing process of second excavation casing Next, the second excavation casing 11 is drawn out to the ground. Along with this extraction, the guide device 12 is extracted from the first excavation casing 1.

(6) Injection test process using water After the second excavation casing 11 is pulled out, ultrahigh pressure water is supplied from the hardening material injection nozzle 7c of the monitor mechanism 7 of the injection pipe rod 14 in the second preceding drilling hole H2. An injection test is performed while injecting in a direction intersecting the alignment direction X of the first preceding hole H1 and the second preceding hole H2. If there is no abnormality in the injection test, the ultra high pressure water is switched to a cement type ultra high pressure hardener and the creation of the ultra high pressure injection wall is started.

(7) Formation process of the first ultra-high-pressure injection wall When the first ultra-high-pressure injection wall 15 is formed, first, as shown in FIG. At the same time as the injection tube rod 14 is pulled up at a predetermined pulling speed in a non-turning state or while swinging and swinging at a slight swinging pivot angle, as shown in FIG. 7c is continuously injected with a predetermined discharge amount and discharge pressure in a direction crossing the arrangement direction X of the first preceding hole H1 and the second preceding hole H2, and compressed air is supplied to each compressed air. The ground is cut and agitated by the jet nozzle G from the jet nozzle 7d, and at the same time, the ultra high pressure hardening wall 15 is filled with the ultra high pressure hardened material, and the first cross section of the super high pressure jet wall 15 having a plate shape (plate shape) is formed. Create. After the formation, the supply of the ultra-high pressure cured material and compressed air is stopped, and the second injection tube rod 14 is pulled out to the ground.

(8) Drawing process of the first excavation casing After the formation of the first ultra-high pressure injection wall 15, although not shown, the first excavation casing 1 is drawn to the ground.

(9) Formation process of the second ultra-high pressure injection wall After the first excavation casing 1 is pulled out, the injection pipe rod 4 in the first preceding drilling hole H1 is not swung at a predetermined pulling speed. At the same time, as shown in FIG. 8, at the same time, the super high pressure curing material is continuously pulled out from the curing material injection nozzle 7c with a predetermined discharge amount and discharge pressure. While jetting in a direction intersecting the alignment direction X of the first preceding drilling hole H1 and the second preceding drilling hole H2, compressed air is jetted from the compressed air jet nozzle 7d, and the ground is cut by the jet G At the same time as stirring, the cutting region is filled with an ultrahigh pressure curing material, and the ultrahigh pressure ejection wall 16 having a plate-like cross section in the wall thickness direction of the ultrahigh pressure ejection wall 15 is formed in a laminated form, The creation is completed (see FIG. 8). After completion of the formation, the supply of the ultrahigh pressure hardener and compressed air is stopped, and the first injection tube rod 4 is pulled out to the ground as shown in FIG.

(10) Cleaning and filling hole of injection tube rod After the first and second injection tube rods 4 and 14 are pulled out, the inside of each rod 4 and 14 is cleaned with fresh water and moved to the next formation point. A hole 17 (see FIG. 3B) generated above the ultrahigh pressure injection wall by pulling out the injection tube rods 4 and 14 is filled with mud or mortar.

  In the above embodiment, the two ultrahigh pressure injection walls 15 and 16 are laminated and integrated in the wall thickness direction so that they can be effectively used for the water blocking wall, the reinforcing retaining wall, etc., but in order to increase the wall thickness further. Three or more ultrahigh pressure injection walls may be laminated and integrated in the wall thickness direction.

  As described above, the ground improvement method as described above includes at least two excavation casings 1 and 11 that respectively form the first preceding drilling hole H1 and the second preceding drilling hole H2, and the head. Two swivels 5 having an ultra-high pressure hardener inlet 5a and a compressed air inlet 5b are assembled, and two in a point-symmetrical arrangement with the tube axis O of the monitor tube 8 being the center of symmetry on the outer periphery of the monitor tube 8 at the tip. The same structure as the first injection tube rod 4 and the first injection tube rod 4 built in the first excavation casing 1 is assembled. The second injection pipe rod 14 constructed in the second excavation casing 11 and a guide device for inserting and guiding the second excavation casing 11 along the first excavation casing 1 in parallel. 12 can be easily performed by using a jet grouting type soil improvement device including a.

  An ultra-high pressure injection wall 15 having a plate-like cross-sectional shape on the first sheet and an ultra-high pressure injection wall 16 having a plate-like cross-sectional shape on at least a second sheet are laminated and integrated in the wall thickness direction. As shown in FIG. 8, the wall surfaces W1 and W2 on both sides in the thickness direction can be formed flat while ensuring a predetermined wall thickness, whereby the entire cross-sectional shape of the ultra-high pressure injection walls 15 and 16 is increased. It can be used as a structural strength that can resist the external force of earth pressure and water pressure, and it is economical because it has good yield and no waste of materials.

  Further, when the super-high pressure injection walls 15 and 16 having such a cross-sectional shape are plate-like, the injection tube rods 4 and 14 are swung in a non-turning state or with a slight turning angle even if they are turned. Since it is sufficient to pull it up while turning, it can be formed in a remarkably short time compared to the conventional forming time, and the flight distance of the ultra-high pressure cured material can be extended.

DESCRIPTION OF SYMBOLS 1 1st excavation casing 4 1st injection pipe rod 5 Swivel 5a Ultra high pressure hardening material inlet 5b Compressed air inlet 7 Monitor mechanism 7c Hardening material injection nozzle 7d Compressed air injection nozzle 8 Monitor pipe 11 2nd excavation casing 12 Guide apparatus 12a, 12b Short cylinder 12c Connecting member 14 Second injection tube rod 15 First ultrahigh pressure injection wall 16 Second ultrahigh pressure injection wall H1 First preceding drilling hole H2 Second preceding drilling

Claims (3)

At least two excavation casings and a swivel having an ultra-high pressure hardener inlet and a compressed air inlet at the head are assembled, and a point-symmetric arrangement with the center of the tube axis of the monitor tube at the tip is symmetrical Prepare at least two injection tube rods assembled with a monitor mechanism provided with two hardener injection nozzles in relation,
First, the drilling casing of the first run to form a ground of the insertion to the first one of the preceding cutting hole to target depth, like an anchor the first run the injection pipe rod in the first run of the drilling casing, then The second drilling casing is inserted into the first drilling casing to the target depth in the ground along the first drilling casing through the guide device, and the second preceding drilling hole is arranged adjacent to the first preceding drilling hole. The second injection pipe rod is installed in the second excavation casing, and then the second excavation casing is pulled out. Then, the second injection pipe rod is attached to the two pieces of the monitor pipe. The ultra high pressure hardened material from the hardener jet nozzles and the compressed air from the compressed air jet nozzles around the hardener jet nozzles to the alignment direction of the first and second preceding holes, respectively. Continuous in crossing direction By pulling up while spraying, the ground is cut and stirred by the high-pressure hardened material continuously jetted and the high-pressure jet of compressed air to form a plate-shaped ultrahigh-pressure jet wall. After pulling out the first excavation casing, the first injection tube rod is supplied with the super high pressure cured material from the two cured material injection nozzles of the monitor tube, and compressed air is supplied from the compressed air injection nozzles around each of the cured material injection nozzles. And the ultra-high pressure curing material that is continuously ejected by continuously ejecting the material from the monitor tube of the second ejection tube rod and the parallel injection direction of the compressed air. And the ground is cut and agitated with a high-pressure jet of compressed air, and a super-high pressure injection wall having a plate-like cross-sectional shape is laminated in the thickness direction of the ultra-high pressure injection wall. , Jet grout formulas ground improvement method. A first excavation casing that is inserted to a target depth in the ground to form a first preceding drilling hole;
Two hardeners in a point-symmetrical arrangement with the center of the tube axis of the monitor tube as the center of symmetry on the outer periphery of the monitor tube at the tip, with a swivel having an ultrahigh pressure hardener inlet and a compressed air inlet at the head A first injection pipe rod built in the first excavation casing, the monitor mechanism provided with the injection nozzle being assembled;
A second excavation casing that is inserted to a target depth in the ground and forms a second preceding drilling hole in parallel with the first preceding drilling hole;
The second excavation casing is provided between the first excavation casing and the second excavation casing so that the second excavation casing is inserted and guided in parallel with the first excavation casing, and the second excavation casing is brought into the ground. A guide device that slides along the first excavation casing and is carried into the ground as it is inserted ;
A second injection tube rod configured in the same configuration as the first injection tube rod and built in the second excavation casing;
Equipped with a,
The first cross-sectional shape formed by pulling up the second injection tube rod is the second cross-section formed by pulling up the first injection tube rod with respect to the plate-like ultrahigh pressure injection wall. The plate-shaped ultra-high pressure injection wall is laminated in the thickness direction, and at least two plate-shaped ultra-high pressure injection walls are integrally laminated in the thickness direction . Jet grout type ground improvement device.   3. The jet grout type according to claim 2, wherein the guide device is formed by arranging two short cylinders that can be slidably fitted to the first excavation casing and the second excavation casing in a glasses shape and connected by a connecting member. Ground improvement device.

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