JP2763430B2 - Soil improvement method under injection of groundwater and packer for injection pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for cutting ground by using high-pressure jetting force of grout or water, air, etc., for a ground having a high groundwater level or under pressure, for example, a deep ground. Improvement method of ground to form unity,
And a packer device for an injection pipe used in this method.

[0002]

2. Description of the Related Art In recent years, the ground has been cut by injecting grout such as cement milk at high pressure from near the tip of an injection pipe, or by injecting compressed air along the high-pressure grout or by injecting high-pressure water along with the compressed air. At the same time, a ground improvement method (jet grout method) using a jet jet that forms a consolidated body in the ground by stirring and mixing the cut soil and grout has been put to practical use.

In recent years, along with the construction of shafts having a relatively large depth, it has become necessary to improve the bottom portion for the purpose of preventing boiling and heaving. The following problems have been encountered when attempting to construct from the ground on a ground having a high level of pressurized water below the ground level.

[0004] The distance between the cutting position and the discharge port is long, and it becomes difficult to discharge the cutting earth and sand.

[0005] At the time of piercing with a casing or directly piercing with an injection pipe, groundwater containing mud is spouted from around the pipe, making it difficult to perform the piercing operation.

[0006] When grout is injected or injected, grout is ejected to the ground together with the water to be pressurized, and the formed diameter cannot be secured.

[0007] It is difficult to ensure the accuracy of drilling the casing or the injection pipe.

A large torque is required for a drilling machine such as an injection pipe, and a large model and a large work area are required.

It is necessary to greatly increase the strength of devices such as an injection pipe and a tip nozzle.

[0010] The accuracy of core sampling is reduced, and it is difficult to confirm the improvement effect.

[0011] The ratio of the perforated length to the improved length is increased, which significantly increases the cost.

There are a number of problems, and practical application has been delayed.

The present invention has been made in view of the above problems. The purpose is to improve the ground under the pressure of groundwater by using the conventional technology and equipment for the shallow depth ground as a basis, and to improve the ground, especially the deep ground ground improvement method and this method. Performing drilling and pulling with casing and injection pipe etc. while controlling the injection of groundwater, excavated earth and sand, grout etc. from the mouth of the injection pipe inserted into the improved ground when constructing from the construction base below the groundwater level with It is to propose a packer device that can be.

The ground improvement method under pressure of ground water according to the invention of the above (1) is a method of drilling the ground with high-pressure water, filling the grout, or directly mixing the grout with the ground by injection of the high-pressure grout. In the improvement method of the ground under the pressure of the groundwater by the jet jet forming the solidified body, the injection pipe is inserted into the improved ground, the jet jet is injected, and the discharge pressure of the mud rising from around the injection pipe is controlled by the pressure regulator. And the amount of sludge is controlled accordingly. The improved construction method according to the invention of (2) is a method in which a ground is filled with grout while the ground is drilled with high-pressure water or ground water is jet-mixed directly with the ground by jetting high-pressure grout to form a consolidated body. In the improvement method under pressure, a construction base is installed in a shaft excavated to a predetermined depth, the depth from the construction base to the improved ground is made shallow, and a jet jet is injected by inserting an injection pipe from the construction base to the improved ground Then, the discharge pressure of the sludge rising from the periphery of the injection pipe is made appropriate by using a pressure adjusting device, and thereby the amount of the sludge is controlled. The packer device of the injection pipe according to the invention of (3) improves the ground under the pressure of the groundwater by the jet jet,
It is a mouth-packer device of the injection pipe at the time of spraying and constructing a jet jet using the casing pipe and the injection pipe from the construction base on which the groundwater pressure acts, and has a cylindrical space through which the casing pipe and the injection pipe can be inserted, The lower end has a fitting part that fits into the construction base, and the upper end has a packer ring for casing pipe and a packer ring for injection pipe at the upper and lower two stages, and the sludge pipe branches from the middle part and communicates with the cylindrical space And a pressure adjusting device is provided.

[0015]

In the ground improvement method according to the invention of the item (1), the drainage pressure is detected by a pressure adjusting device, and drainage is performed based on an adjusted pressure set in advance in consideration of a groundwater pressure, a jet water, and a filling amount of grout. Because the amount of mud is controlled, the inside of the ground does not have a remarkably high pressure, and excess mud and grout are not discharged.
The ground can be improved by filling the ground with a desired amount of grout or mixing it. According to the improved construction method of the invention of (2), the ground is excavated, a construction base is provided in the shaft, and the depth to the ground to be improved is reduced. Can be set to 50 m or less. Therefore, problems associated with a large depth, such as a long drilling distance, drilling accuracy, drilling machine capacity, strength, and discharge of cutting earth and sand, can be solved based on conventional techniques and equipment. In addition, deep ground often has high groundwater pressure, which makes it difficult to secure the formation diameter due to the confined water and to control the change.
By controlling the amount of sludge discharged on the basis of the adjustment pressure in the same manner as in the improvement method of item (1), a desired amount of grout can be filled in the ground to improve the ground.

In many cases, the construction base in the shaft where the ground has been dug is located at a position lower than the groundwater level, and the groundwater pressure acts. When a casing pipe or an injection pipe is inserted, groundwater or grout spouts from around the pipe. The packer apparatus for an injection pipe according to the invention of (3) includes a casing pipe packer ring and an injection pipe packer ring in two upper and lower stages. During installation of the inserted injection pipe or withdrawal of the casing pipe and the injection pipe, it is possible to prevent the spouting of groundwater, cut sand, grout, etc. from the mouth. In addition, a pressure regulator is attached to detect the pressure of the sludge rising from around the injection pipe and control the amount of sludge, so that grout can be filled and mixed even on ground where deep groundwater pressure is high. It can be performed accurately.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The basic concept of the present construction method will be described in the case of a system not using a casing pipe. FIG. 1 shows a construction example of ground improvement at the bottom of a shaft at a large depth. The ground 1 to be improved at the bottom of the shaft has a depth of 50 m or more. Prior to the ground improvement, the ground is surrounded by a continuous underground wall 2 and the inside thereof is excavated to construct a construction base 3. The construction base 3 is preferably set at a depth position where the depth D to the target ground 1 is 50 m or less. The groundwater level is higher than the third place of the construction base.

A lower-floor concrete 4 is laid on the surface of the construction base 3, and a double-pipe rod is inserted through the lower-floor concrete 4 to the target ground 1 as an injection pipe 5 for sending high-pressure grout and compressed air. Injection pipe 5 Lower floor concrete 4
Is closed airtightly by the mouth packer 6. The injection pipe 5 is provided with a boring machine 7 for driving rotation of a rod at an upper end thereof, and is connected to a compressor 8, a water pump 9, and a high-pressure pump 10 installed on the ground surface via a feed pipe 11. Further, the pressure adjusting device 12, the flow meter 13, and the sedimentation tank 14 are connected in series through a drainage pipe 15 in communication with the mouth packer 6. After piercing the injection tube 5 to a certain depth,
The grout and the ground are agitated and mixed while cutting the ground by injecting high-pressure grout and compressed air from the tip.

The cutting sand produced during the construction work rises along the periphery of the injection pipe 5 with the compressed air, and is discharged as sludge through the drainage pipe 15 communicating with the mouth packer 6. The pressure adjusting device 12 attached to the vicinity of the mouth packer 6 of the exhaust pipe 15 detects the exhaust pressure passing through the periphery of the injection pipe 5 and entering the exhaust pipe, and based on the preset adjustment pressure, the exhaust pipe is used as a reference. Open and close the valve and discharge. The sludge is measured by a flow meter 13 and then collected in a sedimentation tank 14.

An appropriate value is selected as the adjustment pressure set in the pressure adjustment device, taking into account the pore water pressure in the ground, the amount of jet water, the filling amount of grout, and the like. In addition, the valve pressure can be controlled and opened and closed as needed to prevent the earth and sand, grout or groundwater from being discharged more than necessary.

A solid body 1 is attached to the target ground 1 at the bottom of a predetermined shaft.
After making the ground 6 and improving the ground, the jet injection is stopped, and the filling is performed by grouting while the injection pipe 5 is pulled out. After pulling out the injection pipe 5, the open / close valve attached to the mouth packer 6 is closed and closed.

The present invention relates to a ground improvement method for a ground on which pressurized water acts, and in principle, a construction base is provided in a shaft when the ground is deep. However, under extremely high pressure conditions, such as when groundwater spouts out from the ground, it is often necessary to construct from the ground without providing a construction base in the shaft. In each case, the construction base is filled with grout and mixed to form an improved consolidated body while preventing the pressurized water from being blown out and appropriately controlling the discharge of the cutting sand.

In this method, a casing pipe is generally used for drilling, rather than a case where an injection pipe is used for drilling without using a casing pipe.

For this purpose, in the present invention, a mouth packer 6 shown in FIG. 2 is used. Mouth packer body portion 17 has a cylindrical shape, wear part 1 fitting the lower end portion Komu fitted under the floor concrete 4
8 and two upper and lower stages of a casing pipe packing ring 19 and an injection pipe packing ring
0, an opening / closing valve 21 is attached to the lower side thereof, and a mud pipe 15 branches below the opening / closing valve 21.
2 and the opening / closing valve 22 are attached. Hereinafter, an embodiment of the construction using the mouth packer 6 will be described in which a triple pipe rod for sending high-pressure water, compressed air, and grout is used as an injection pipe,
The case of using a casing pipe for drilling will be described in detail with reference to the drawings.

In FIG. 3, first, a perforation is made using a casing pipe 23 into which an injection pipe is inserted. The casing pipe 23 is provided with a drill bit 24, a check valve 25, and a release device 26 at the tip. The mouth of the upper end is hermetically sealed with a casing pipe packing ring 19 and rotated. To penetrate the ground. A check valve 25 is provided at the distal end, and groundwater does not flow upward through the casing pipe 23. Excavated earth and sand, drilling water, and the like generated during the drilling operation are discharged from the drainage pipe 15 by adjusting the discharge pressure by the pressure adjusting device 12 and opening and closing the open / close valve 22.

After piercing the casing pipe 23 to a predetermined depth, a triple pipe rod (φ900 mm) is inserted into the casing pipe 23 as the injection pipe 5 as shown in FIG. The gap between the casing pipe 23 and the injection pipe 5 is sealed by an entrance packing 27 attached to the upper end of the injection pipe 5,
The release device 26 is pushed by the tip of the rod 5 to release the check valve 25 and the drill bit 24 at the tip of the casing pipe.

Subsequently, the drawing of the casing pipe 23 is started. Immediately after the lower end of the casing pipe 23 has passed the position of the injection pipe packer ring 20, the periphery of the injection pipe 5 is sealed by the packer ring 20 to prevent spout of soil and the like from the mouth of the injection pipe 5, 23 is removed (FIG. 5).

As shown in FIG. 6, the injection pipe 5 jets jet water and compressed air 28 while rotating the injection pipe 5 on the target ground 1 at the bottom to be ground-removed, and cuts the ground and grouts the grout 29. After the filling, the solidified body 16 is formed by stirring and mixing while pulling out the injection tube 5 (FIG. 7).
The injection pipe 5 is pulled out, and the opening and closing valve 21 attached to the mouth packer 6 and the opening and closing valve 22 of the mud pipe 15 are closed.
Close the drill hole.

[0029]

The method for improving the deep ground according to the invention of the item (1) is intended for the ground under the pressure of the groundwater. ,
Even if the ground is subjected to a high groundwater pressure, the ground can be improved by filling a desired grout. The improvement method (2) is more preferable because the work is carried out based on the conventional technology and equipment since the work is carried out from the construction base in the shaft that is dug down.

The injection pipe packing apparatus according to the third aspect of the present invention prevents the injection of groundwater, earth and sand, or grout from the surrounding mouth of the injection pipe and the casing pipe during construction from a construction base lower than the groundwater level. By controlling the mud pressure, the amount of mud is controlled to enable improvement of deep ground.

[Brief description of the drawings]

FIG. 1 is an overall sectional view of a method for improving deep ground in an embodiment.

FIG. 2 is a sectional view of a mouth packer device.

FIG. 3 is a cross-sectional view showing a state where a casing pipe has penetrated into the ground through a mouth packer device.

FIG. 4 is a cross-sectional view showing a state where an injection pipe has penetrated into the ground through a casing pipe.

FIG. 5 is a sectional view of an injection pipe penetrating into the ground.

FIG. 6 is a cross-sectional view of an injection pipe for jetting jet water, compressed air, and grout in the ground.

FIG. 7 is a cross-sectional view of an injection pipe withdrawn from the ground.

FIG. 8 is a cross-sectional view of the improved ground after the ground improvement work.

[Explanation of symbols]

1 ... ground to be improved, 2 ... underground continuous wall, 3 ... construction base,
4 ... lower floor concrete, 5 ... injection pipe, 6 ... mouth packer, 7 ... boring machine, 8 ... compressor, 9 ... water pump, 10 ... high pressure pump, 11 ... feed pipe, 12 ... pressure regulator, 13 ... flow rate Total: 14: sedimentation tank, 15: sludge pipe, 16: solidified body, 17: mouth packer body, 18 ...
Fitting part, 19 ... Packer ring for casing pipe, 2
0: Packer ring for injection pipe, 21, 22: open / close valve, 23: casing pipe, 24: drill bit, 25
... check valve, 26 ... release device, 27 ... entra packing, 28 ... jet water and compressed air, 29 ... grout.

Claims (3)

(57) [Claims] 1. Ground improvement under pressure of groundwater by a jet jet that forms a consolidated body by filling grout or directly mixing grout with the ground by injection of high-pressure grout while drilling the ground with high-pressure water. In the construction method, the injection pipe is inserted into the improved ground to jet the jet jet, and the discharge pressure of the sludge rising from the periphery of the injection pipe is made appropriate using a pressure adjusting device, thereby controlling the amount of the sludge. Characteristic soil improvement method under pressure of groundwater. 2. Ground improvement under pressure of groundwater by a jet jet that fills grout or directly mixes grout with the ground by injection of high-pressure grout while drilling the ground with high-pressure water to form a consolidated body. In the construction method, a construction base is installed in a shaft that has been dug down to a predetermined depth,
Reduce the depth from the construction base to the improved ground, insert an injection pipe from the construction base into the improved ground, jet a jet jet, and adjust the discharge pressure of the mud rising from around the injection pipe using a pressure adjustment device to be appropriate. A ground improvement method under pressure of groundwater, characterized in that the amount of sludge is controlled accordingly. 3. A packing machine at the mouth of an injection pipe when jetting a jet jet from a construction base on which the groundwater pressure acts using a casing pipe and an injection pipe to perform the ground improvement under the pressure of the groundwater caused by the jet jet. A cylindrical space through which the casing pipe and the injection pipe can be inserted, a lower end part of which forms a fitting part to be fitted into the construction base, and an upper end part provided with a casing pipe packer ring and an injection pipe packer ring in upper and lower two stages. A packer device for an injection pipe, characterized in that a drainage pipe is branched from an intermediate part, and is connected to a cylindrical space and is provided with a pressure regulator.