JP6490475B2 - Ground improvement method using special multiple pipes. - Google Patents

Description

  The present invention relates to a ground improvement method for improving the ground by creating a columnar ground improvement body in the ground for the purpose of increasing the strength of the ground or purifying contaminants in the ground, and in particular, such as gravel and cobblestone. The present invention relates to a ground improvement method using a special multiple pipe for improving a ground by creating a columnar ground improvement body in a ground having a hard ground layer.

  Conventionally, as shown in FIG. 14, a ground improvement method for improving the ground by creating a columnar ground improvement body in the ground where a hard ground layer such as gravel or cobblestone exists for the purpose of increasing the strength of the ground. First, a pre-excavation operation for excavating to a predetermined depth in the ground is performed. As the preceding excavation work, a cylindrical casing pipe 31 that goes up and down is provided, a screw shaft 32 that goes up and down is provided inside the casing pipe 31, and a screw blade 33 that performs soil removal on the outer periphery of the screw shaft 32. An attached biaxial coaxial auger 30 is used. The biaxial coaxial auger 30 is mounted on a construction machine 34, and the construction machine 34 excavates the biaxial coaxial auger 30 to a predetermined depth in the ground. After penetrating, the construction machine 34 pulls out the biaxial coaxial auger 30 from the ground to excavate to a predetermined depth in the ground. In addition, intrusion while excavating to a predetermined depth in the ground by the biaxial coaxial auger 30, even if a hard ground layer such as gravel or cobblestone exists in the ground, the excavation is surely made to a predetermined depth. It is possible to penetrate.

  Next, as shown in FIG. 15, after performing the preceding excavation work, a ground improvement body creation work is performed in which cement milk is injected into the ground to create a ground improvement body T. As this ground improvement body construction work, a deep mixer 35 provided with a pipe rod 36 that goes up and down, a plurality of stirring blades 37 attached to the lower end of this pipe rod 36, and an injection port 38 for jetting cement milk was provided. The deep mixer 35 is mounted on the construction machine 39, and cement milk is sprayed from the injection port 38 at the lower end of the tube rod 36 to the portion excavated by the preceding excavation work, with a plurality of stirring blades 37. A ground improvement body T is created in the ground by kneading the injected cement milk and the original ground soil, and performing this downward to a predetermined depth.

  In this way, by performing two operations, a prior excavation work for excavating to a predetermined depth in the ground, and a ground improvement body creation work for injecting cement milk into the ground to create a ground improvement body T, A columnar ground improvement body T is created in the ground where a hard ground layer such as cobblestone exists to improve the ground.

  In this conventional ground improvement method, using a construction machine equipped with a biaxial coaxial auger, a pre-excavation operation is performed to excavate to a predetermined depth in the ground with this biaxial coaxial auger. After performing the pre-excavation work, using another construction machine equipped with a deep mixing machine, the ground improvement body is created by injecting cement milk into the ground with this deep mixing machine. In short, it was necessary to carry out two operations: a prior excavation operation and a ground improvement body construction operation. For this reason, there are a large number of work processes, a large number of construction machines and facilities, and the workability becomes very bad, so there is a problem that the construction period in the ground improvement work becomes long and the construction cost becomes high. there were.

  Therefore, in view of such problems, the present invention creates a columnar ground improvement body in the ground by a single operation without performing two conventional excavation work and ground improvement body creation work. By making it possible to improve the ground, the work process in the ground improvement work can be greatly reduced, and by improving workability, the work period in the ground improvement work can be shortened and the construction cost can be reduced. An object of the present invention is to provide a ground improvement method using a special multiple pipe that can be made inexpensive.

  1st invention is equipped with the cylindrical casing pipe | tube which goes up and down, is equipped with the cylindrical screw pipe | tube which goes up and down inside this casing pipe | tube, and the helical screw blade | wing which carries out a soil discharge to the outer periphery of this screw pipe | tube At the same time, using a special multi-pipe with a plurality of through-holes penetrating vertically in the screw blades, this special multi-pipe is penetrated while drilling to a predetermined depth in the ground. Improving material or soil sprayed at the lower end of the pipe into the special multiple pipe and the casing pipe and the screw pipe of the special multiple pipe are rotated and injected through the through holes provided in the screw blades of the screw pipe Columnar ground improvement in the ground by kneading the improved soil or soil purification material and the original ground soil in a special multi-pipe while moving the purification material up and down. And construct a a ground improvement method using a special multi-tube to perform the improvement of the ground.

The second invention is the first invention wherein when the improvement material or soil purification material is injected into the special multiple pipe at the lower end of the special multiple pipe and the improvement material or soil purification material is mixed with the original ground soil, the special multiple pipe is used. This is a ground improvement method using a special multiple pipe that is made without moving the casing pipe and screw pipe up and down.

  A third invention relates to the first invention, when the improvement material or soil purification material is injected into the special multiple pipe at the lower end of the special multiple pipe to knead the improvement material or soil purification material and the original ground soil. This is a ground improvement method using a special multi-pipe which is performed while moving the casing pipe and the screw pipe upward or downward.

  According to a fourth invention, in any one of the first, second, and third inventions, in the improvement material or the soil purification material that is injected into the special multiple pipe at the lower end of the special multiple pipe, the raw material discharged from the casing pipe is used. This is a ground improvement method using a special multiple pipe in which the amount of improvement material or soil purification material sprayed from the injection port is controlled so as to spray the amount of improvement material or soil purification material substantially equal to the amount of ground soil discharged.

  According to the present invention, a special multiple pipe is used to penetrate the special multiple pipe while excavating to a predetermined depth in the ground. After the penetration, the improvement material or the soil purification material is injected into the special multiple pipe, and the screw. By mixing the improvement material or soil purification material and the original ground soil in the special multi-pipe while moving the improvement material or soil purification material sprayed by the through holes provided in the screw blades of the pipe in the vertical direction, By creating a ground improvement body, a columnar ground improvement body can be created in the ground by one such work without performing the two operations of prior excavation work and ground improvement body creation work as in the past. As a result, the work process in the ground improvement work can be greatly reduced, and the work period in the ground improvement work can be shortened by improving workability. It can also be less expensive

  Moreover, in the improvement material or the soil purification material injected into the special multiple pipe at the lower end of the special multiple pipe, the improvement material or the soil purification material is injected in substantially the same amount as the discharge amount of the ground soil discharged from the casing pipe. By controlling the injection amount of the improvement material or soil purification material from the injection port, the amount of improvement material or soil purification material used can be minimized, and the improvement material or soil purification material used The amount can be reduced and the cost can be reduced. In addition, by minimizing the amount of improved material or soil purification material used, the amount of the improved material or soil purification material and raw ground soil mixed on the ground surface can be reduced. The work can be greatly reduced and the work can be made easier.

It is explanatory drawing of the special multiple tube in this invention. It is explanatory drawing of the screw pipe of the special multipipe in this invention. It is an AA expanded sectional view of FIG. It is explanatory drawing of the construction machine which mounts the special multiple pipe | tube in this invention, and its peripheral equipment. (A) It is explanatory drawing of the ground improvement construction method using the special multiple pipe | tube of this invention. (B) It is explanatory drawing of the ground improvement construction method using the special multiple pipe | tube of this invention. (C) It is explanatory drawing of the ground improvement construction method using the special multiple pipe | tube of this invention. (D) It is explanatory drawing of the ground improvement construction method using the special multiple tube of this invention. (E) It is explanatory drawing of the ground improvement construction method using the special multiple pipe | tube of this invention. (F) It is explanatory drawing of the ground improvement construction method using the special multiple tube of this invention. (G) It is explanatory drawing of the ground improvement construction method using the special multiple pipe | tube of this invention. It is explanatory drawing which shows the kneading | mixing state of cement milk and raw ground soil in the ground improvement construction method using the special multiple pipe | tube of this invention. (A) It is explanatory drawing of another example of the ground improvement construction method using the special multiple pipe | tube of this invention. (B) It is explanatory drawing of another example of the ground improvement construction method using the special multiple pipe | tube of this invention. (C) It is explanatory drawing of another example of the ground improvement construction method using the special multiple pipe | tube of this invention. (D) It is explanatory drawing of another example of the ground improvement construction method using the special multiple pipe | tube of this invention. (E) It is explanatory drawing of another example of the ground improvement construction method using the special multiple pipe | tube of this invention. (F) It is explanatory drawing of another example of the ground improvement construction method using the special multiple pipe | tube of this invention. (G) It is explanatory drawing of another example of the ground improvement construction method using the special multiple pipe | tube of this invention. It is explanatory drawing of another example of the special multiple tube in this invention. It is explanatory drawing of another example of the special multiple tube in this invention. It is explanatory drawing which shows the result of the test of the ground improvement body created in the ground. It is explanatory drawing which shows the result of the test of the ground improvement body created in the ground. It is explanatory drawing of the conventional ground improvement construction method. It is explanatory drawing of the conventional ground improvement construction method.

  One embodiment of the ground improvement method using the special multiple pipe of the present invention will be described. In addition, what is demonstrated here improves the ground by creating a columnar ground improvement body in the ground for the purpose of increasing the strength of the ground.

  First, the special multiple pipe will be described. As shown in FIGS. 1, 2, and 3, the special multiple pipe 1 includes a cylindrical casing pipe 2 that extends vertically, and a plurality of pipes are provided at the lower end of the casing pipe 2. Attach a bit 3 for excavation. Further, the casing pipe 2 is provided with a plurality of discharge window portions 4 extending in the vertical direction so that the raw ground soil discharged by the discharge window portions 4 can be discharged from the inside of the casing pipe 2 to the outside.

  An inner side of the casing tube 2 is provided with a drilling head 6 provided with a cylindrical screw tube 5 extending vertically, and a plurality of excavation bits 7 attached to the lower end of the screw tube 5. Are provided with a plurality of injection ports 8. Further, the inside of the screw pipe 5 is a conduit, and water or cement milk, which is an improvement material, and air are allowed to pass therethrough, so that water or improvement can be made from the injection port 8 provided in the excavation head 6. It will be possible to inject cement milk and air. This improvement material is cement milk, but it may be a mixture of various additives with this cement milk. Furthermore, the present invention is not limited to this. Other things such as things may be used.

  In addition, in the screw pipe 5 provided inside the casing pipe 2, the inside becomes a pipe line through which water or cement milk, air or the like which is an improvement material passes, 5 may be provided with a dedicated pipe for water or improved material such as cement milk or air, and water or improved material such as cement milk or air may pass through the dedicated tube.

  Further, a spiral screw blade 10 for soil removal is attached to the outer periphery of the screw tube 5, and the screw blade 10 has a diameter slightly smaller than the inner diameter of the casing tube 2. The screw blade 10 is provided with a plurality of through-holes 11 penetrating in the vertical direction. For example, the through-holes 11 are formed in a circular shape having a diameter that is about half the width of the screw blade 10, and are provided at four locations that are equally spaced in the circumferential direction of the screw blade 10. . The through hole 11 is not limited to this, and may have other shapes and sizes such as a triangular shape, a quadrangular shape, a semicircular shape, and a fan shape. Two, three, or five locations may be used. A grid 12 in which bars are assembled vertically and horizontally is attached to the through-hole 11, and the grid 12 can surely discharge large objects such as gravel and cobblestone. Note that the lattice 12 is not necessarily attached to the through hole 11, and the lattice 12 may not be attached depending on the shape and size of the through hole 11.

  On the other hand, the construction machine 20 to which the special multiple pipe 1 is mounted and its peripheral equipment will be described. As shown in FIG. 4, as the construction machine 20, a mast 22 is erected in front of the vehicle body 21. A special multi-tube 1 is attached along. The mast 22 of the construction machine 20 is provided with an elevating device 23 for penetrating and withdrawing the attached special multiple pipe 1 into the ground, and rotating the casing pipe 2 and the screw pipe 5 of the special multiple pipe 1 respectively. A rotating device 24 is provided.

  The peripheral equipment includes a cement silo 25, a cement generating device 26, and a pump 27. The cement raw material flowing from the cement silo 25 is generated into cement milk in the cement generating device 26, and the generated cement milk is pumped. 27 is supplied to the special multiple tube 1. A compressor 28 is also provided, and air is supplied from the compressor 28 to the special multiple pipe 1. Further, although not shown, water is also supplied to the special multiple pipe 1.

  Next, the ground improvement method using this special multiple pipe will be described. In addition, about the target ground which improves the ground by the ground improvement method using this special multiple pipe, a hard ground layer such as gravel or cobblestone exists in the ground. However, it is not limited to such ground.

  As shown to Fig.5 (a), the casing pipe | tube 2 and the screw pipe 5 of the special multiple pipe | tube 1 with which the construction machine 20 was mounted | worn are rotated, and it penetrates in the ground in which hard ground layers, such as a gravel and a cobblestone, exist.

  And as shown in FIG.5 (b), it penetrates, excavating with the excavation head 6 of the lower end of the casing pipe | tube 2 and the screw pipe 5, and in order to assist excavation at this time, in order to assist excavation, the injection port 8 of the excavation head 6 Water is jetted from. Moreover, soil is discharged by the screw blades 10 of the screw tube 5, and the original ground soil is discharged from the discharge window 4 of the casing tube 2 onto the outside ground surface.

  And as shown in FIG.5 (c), it penetrates, excavating the casing pipe | tube 2 and the screw pipe 5 of the special multiple pipe | tube 1 to the predetermined depth in the ground. In addition, in the penetration while excavating the special multiple pipe 1 with the casing pipe 2 and the screw pipe 5, even if a hard ground layer such as gravel or cobblestone exists in the ground, it is surely excavated to a predetermined depth. Can penetrate.

  Then, as shown in FIG. 6 (d), after the casing tube 2 and the screw tube 5 of the special multiple tube 1 are penetrated to a predetermined depth in the ground, the inside of the screw tube 5 of the special multiple tube 1 is improved with an improving material. Cement milk and air are supplied, and cement milk and air, which are improved materials, are injected into the special multiple pipe 1 from a plurality of injection ports 8 provided in the excavation head 6 at the lower end of the screw pipe 5.

  And as shown in FIG.6 (e), the casing pipe | tube 2 and the screw pipe 5 of the special multiple pipe | tube 1 were stopped without moving up and down, the casing pipe | tube 2 and the screw pipe | tube 5 were rotated, and the injected cement The milk and the ground soil in the special multiple pipe 1 are kneaded. At this time, as shown in FIG. 7, the injected cement milk and air flow up and down through the through hole 11 provided in the screw blade 10 of the screw tube 5, and thus the screw tube 5 The cement milk and the ground soil in the special multiple pipe 1 are kneaded while moving the cement milk and air injected through the through-holes 11 provided in the screw blades 10 in the vertical direction, thereby mixing the cement milk and the ground soil. Can be carried out satisfactorily and reliably.

  Then, as shown in FIG. 6 (f), when the cement milk and the raw ground soil are kneaded to near the ground surface, as shown in FIG. 6 (g), the casing tube 2 and the screw of the special multiple tube 1 are used. Pull the tube 5 out of the ground. As a result, it is possible to improve the ground by creating a columnar ground improvement body T in the ground.

  In addition, when the kneading of the cement milk and the original ground soil is carried out to the ground surface, the mixture of the cement milk and the raw ground soil is slightly discharged onto the ground surface. By pulling out the casing tube 2 and the screw tube 5 from the ground, a space corresponding to the pulled-out space is created in the ground, so that the cement milk discharged on the ground surface and the original ground soil are kneaded again. It will be drawn into the ground.

  In addition, in the case of cement milk which is an improved material that is injected into the special multiple pipe 1 from the injection port 8 and kneaded with the ground soil, the amount of injection is controlled. This measures the amount of raw ground soil discharged from the casing pipe 2 onto the outside ground surface, and calculates the final discharged amount of raw ground soil. Then, based on the calculated amount of discharge of the ground soil, the amount of cement milk substantially equal to the amount of discharge of the ground soil is finally injected into the special multiple pipe 1 so that the cement milk from the injection port 8 is discharged. Control the amount of injection.

  In this way, the amount of cement milk used is controlled by controlling the injection amount of cement milk from the injection port 8 so that approximately the same amount of cement milk as the discharge amount of the ground soil is injected into the special multiple pipe 1. The amount of cement milk to be used can be reduced and the cost can be reduced. Moreover, in the case of a mixture of cement milk discharged onto the ground surface and the original ground soil, unlike ordinary soil, the disposal process becomes very difficult. Since the amount of discharged soil kneaded can be reduced, waste disposal work of such cement milk and ground soil kneaded can be greatly reduced, and the work can be facilitated.

  As described above, the special multiple pipe 1 is used to penetrate the special multiple pipe 1 while excavating to a predetermined depth in the ground. After the penetration, cement milk and air are injected into the special multiple pipe 1. By mixing the cement milk and the original ground soil in the special multiple pipe 1 while moving the cement milk and air injected by the through holes 11 provided in the screw blades 10 of the screw pipe 5 in the vertical direction, a columnar shape is formed in the ground. By creating the ground improvement body T, the column-shaped ground improvement body T is created in the ground by one such work without performing the conventional two excavation work and the ground improvement body creation work. Therefore, the work process in the ground improvement work can be greatly reduced and workability can be improved.

  Next, another example of the ground improvement method using this special multiple pipe will be described. In the ground improvement method using the above-described special multiple pipe, when cement milk and air are injected into the special multiple pipe 1 to mix the cement milk and the original ground soil, the casing pipe 2 and the screw pipe 5 of the special multiple pipe 1 are used. However, instead of moving up and down, it is performed while moving the casing tube 2 and the screw tube 5 of the special multiple tube 1 upward.

  Specifically, as in the ground improvement method using the special multiple pipe described above, as shown in FIG. 8A, the casing pipe 2 and the screw pipe 5 of the special multiple pipe 1 attached to the construction machine 20 are rotated. It penetrates into the ground. And as shown in FIG.8 (b), it penetrates, excavating with the excavation head 6 of the lower end of the casing pipe 2 and the screw pipe 5. As shown in FIG. The soil is discharged by the screw blades 10 of the screw pipe 5, and the original ground soil is discharged on the ground surface. And as shown in FIG.8 (c), it penetrates, excavating the casing pipe | tube 2 and the screw pipe | tube 5 of the special multiple pipe | tube 1 to the predetermined depth in the ground. Then, as shown in FIG. 9 (d), after the casing tube 2 and the screw tube 5 of the special multiple tube 1 are penetrated to a predetermined depth in the ground, the inside of the screw tube 5 of the special multiple tube 1 is improved with an improving material. Cement milk and air are supplied, and cement milk and air, which are improved materials, are injected into the special multiple pipe 1 from a plurality of injection ports 8 provided in the excavation head 6 at the lower end of the screw pipe 5.

  Then, as shown in FIGS. 9 (e) and 9 (f), while the cement milk and air are injected into the special multiple pipe 1 from the injection port 8, the casing pipe 2 and the screw pipe 5 of the special multiple pipe 1 are moved upward. The casing pipe 2 and the screw pipe 5 are rotated while gradually moving to knead the injected cement milk and the raw ground soil in the special multiple pipe 1.

  Then, when the cement milk and the ground soil are kneaded close to the ground surface, the casing tube 2 and the screw tube 5 of the special multiple tube 1 are pulled out from the ground as shown in FIG. 9 (g). As a result, it is possible to improve the ground by creating a columnar ground improvement body T in the ground.

  In this way, when cement milk and air are injected into the special multiple pipe 1 at the lower end of the special multiple pipe 1 to knead the cement milk and the ground soil, the special multiple pipe 1 is moved upward. As a result, kneading of the cement milk and the base soil can be performed satisfactorily and reliably, and the kneading speed can be increased, that is, the work of mixing the cement milk and the base soil can be shortened. The working time can be shortened.

  In the example explained here, when the cement milk and air are injected into the special multiple pipe 1 to knead the cement milk and the ground soil, the casing pipe 2 and the screw pipe 5 of the special multiple pipe 1 are moved upward. However, as yet another example, the screw pipe 5 of the special multiple pipe 1 may be moved up and down. The machine is stopped without moving up and down, and the cement milk and the ground soil are kneaded while moving only the screw pipe 5 upward and downward.

  In addition, here, the improved material such as cement milk and air were jetted and kneaded with the original ground soil, but only the improved material such as cement milk was jetted and kneaded with the original ground soil. good.

  On the other hand, another example of the special multiple pipe 1 will be described. In the special multiple pipe 1 described above, the injection port 8 for injecting cement milk and air is provided in the excavation head 6 attached to the lower end of the screw pipe 5. However, the present invention is not limited thereto. For example, as shown in FIG. 10, a plurality of injection ports 8 are provided laterally at the lower end of the screw pipe 5 above the excavation head 6, and cement milk is provided from here. And air may be injected into the special multiple pipe 1.

  Further, instead of providing the injection port 8 on the screw pipe 5 side, a plurality of injection ports 8 may be provided at the lower end of the casing tube 2 inward as shown in FIG. Is provided on the casing tube 2 side, it is necessary to form a pipe line from the upper side to the lower side in the casing tube 2, but cement milk and air can be injected from the injection port 8 toward the inside of the casing tube 2, Cement milk can be flowed from the outside to the screw blades 10 of the screw tube 5, whereby the cement milk can flow reliably on the outside so that the cement milk and the ground soil can be mixed very well. it can.

  Further, a plurality of injection ports 8 are provided on both the screw pipe 5 side which is the lower end of the screw pipe 5 and the casing pipe 2 side which is the lower end of the casing pipe 2, and cement milk and air are supplied from both into the special multiple pipe 1. You may make it inject.

  Next, the ground improvement method using the special multiple pipe of the present invention was tested, and will be described below. In this test, the ground improvement body T formed in the ground is examined. In the special multiple pipe 1, a screw blade 10 provided with a plurality of through holes 11 is set as Test Example A, and the through holes 11 are not provided at all. A non-existing sample is designated as Test Example B, and a columnar ground improvement body T is created in the ground using these, and a part of the created ground improvement body T is collected as a sample. The state of the ground improvement body T created by dividing into four parts, a part having a crack, a part having a crack, a part having a soft part, and a defective part was evaluated.

  In this case, the ground improvement method using the special multiple pipe is such that when cement milk and air are injected into the special multiple pipe 1 to knead the cement milk and the original ground soil, the casing pipe 2 of the special multiple pipe 1 and The screw tube 5 is made to stop without moving up and down, and the ground improvement body T created in the ground has a diameter of about 1.6 m and is about 10 m from the ground surface. It was created to the depth. And a sample is extract | collected in the position of 0.4 m from the center of this created ground improvement body T. FIG.

  As a result of the test of the ground improvement body T in Test Example A, as shown in FIG. 12, a place with a depth of about 0 to 0.3 m near the ground surface is defective, and a place with a depth of about 0.3 to 1.3 m. Since it becomes a cracked part, and a place with a depth of about 9.3 to 9.7m is a cracked part, the place is few and all other places are good places. In the ground improvement body T to be created, it can be made extremely good.

  On the other hand, as a result of the test of the ground improvement body T in Test Example B, as shown in FIG. 13, where the depth of about 0 to 0.8 m near the ground surface is defective, the depth is about 0.8 to 2.5 m. Is a place with a soft part, a place with a depth of about 2.5 to 2.8 m is a bad place, a place with a depth of about 2.8 to 3.8 m is a place with a soft part, and a depth of about 5.8 to 6 0.0m is a cracked part, a depth of about 6.6 to 7.8m is a defective part, and a part of about 9.7 to 10m is a soft part. In the ground improvement body T built up to a depth of 10 m, since more than half of the place is not a good place, there will be some problem place, so in the ground improvement body T created in the ground, it is good To do It could not be.

  As is clear from these results, the screw blade 10 that is the test example A provided with a plurality of through holes 11 is better in the ground than the sample that is not provided with the through hole 11 that is the test example B. It can be seen that the ground improvement body T can be created.

  In addition, in the ground improvement method using the above-mentioned special multiple pipe, for the purpose of increasing the strength of the ground, a columnar ground improvement body was created in the ground to improve the ground, However, the present invention is not limited to this. For the purpose of purifying contaminants in the ground, a pillar-shaped ground improvement body may be created in the ground to improve the ground. In the above-mentioned, the improvement material such as cement milk was sprayed from the injection port 8 and the improvement material such as cement milk and the original ground soil were kneaded to form a columnar ground improvement body in the ground. Instead, a soil purification material is sprayed from the injection port 8, and the soil purification material and the original ground soil are kneaded to create a columnar ground improvement body in the ground. Thus, contaminants in the ground are purified by biological treatment (bioremediation) utilizing the decomposition ability of chemical substances possessed by microorganisms in the soil purification material contained in the ground improvement material.

  DESCRIPTION OF SYMBOLS 1 ... Special multiple pipe, 2 ... Casing pipe, 3 ... Bit, 4 ... Discharge window part, 5 ... Screw pipe, 6 ... Excavation head, 7 ... Bit, 8 ... Injection port, 10 ... Screw blade, 11 ... Through-hole , 12 ... lattice, 20 ... construction machine, 21 ... car body, 22 ... mast, 23 ... lifting device, 24 ... rotating device, 25 ... cement silo, 26 ... cement generating device, 27 ... pump, 28 ... compressor, 30 ... two Axial coaxial auger, 31 ... casing tube, 32 ... screw shaft, 33 ... screw blade, 34 ... construction machine, 35 ... deep layer mixer, 36 ... pipe rod, 37 ... stirring blade, 38 ... injection port, 39 ... construction machine

Claims (4)

A cylindrical casing pipe that goes up and down is provided, a cylindrical screw pipe that goes up and down inside the casing pipe, and a helical screw blade that removes soil is attached to the outer periphery of the screw tube. Using a special multiple tube with a plurality of through-holes penetrating vertically in the vertical direction,
This special multiple pipe is penetrated while excavating to a predetermined depth in the ground, and after penetration, an improvement material or soil purification material is injected into the special multiple pipe at the lower end of the special multiple pipe, and the casing pipe and screw of the special multiple pipe Rotating the tube, kneading the improved material or soil purification material and the original ground soil in the special multi-pipe while moving the improved material or soil purification material sprayed by the through holes provided in the screw blades of the screw tube in the vertical direction A ground improvement method using a special multiple pipe, characterized in that the ground is improved by creating a columnar ground improvement body in the ground. When the improvement material or soil purification material is injected into the special multiple pipe at the lower end of the special multiple pipe to knead the improvement material or soil purification material and the base soil, the casing pipe and screw pipe of the special multiple pipe are not moved up and down. The ground improvement method using the special multiple pipe according to claim 1, wherein the ground improvement method is performed.   When the improvement material or soil purification material is sprayed into the special multiple pipe at the lower end of the special multiple pipe and the improvement material or soil purification material and the ground soil are mixed, the casing pipe and screw pipe of the special multiple pipe are moved up or down. The ground improvement method using the special multiple pipe according to claim 1, wherein the ground improvement method is performed. In the improvement material or soil purification material that is injected into the special multiple pipe at the lower end of the special multiple pipe, the improvement material or soil purification material is injected in approximately the same amount as the discharge amount of the ground soil discharged from the casing pipe. The ground improvement method using the special multiple pipe according to any one of claims 1 to 3, wherein an injection amount of the improvement material or the soil purification material from the injection port is controlled.

Images