Drilling-type freezing pipe and foundation freezing method

Abstract

To not only enable drilling while discharging drilling water from an outlet but also prevent leakage of a cooling liquid from the outlet even when internal pressure increases during circulation of the cooling liquid.SOLUTION: A drilling-type freezing pipe 100 comprises: a freezing pipe body 1 having a substrate 16 that closes the inside at an end in the central axis direction and is capable of supplying a cooling liquid into a space inside the substrate 16; a drilling bit 2 provided at the tip of the freezing pipe body 1; a communication path 42 penetrating the substrate 16; an outlet 31 disposed outside the substrate 16 and provided at one end of the communication path 42; a connection port 41 disposed inside the substrate 16 and provided at the other end of the communication path 42; and a water pipe 5 disposed inside the freezing pipe body 1, connected to the connection port 41, and capable of feeding drilling water to the outlet 31. The communication path 42 includes a plug insertion part 44 into which a plug 6, inserted through the connection port 41 to close the communication path 42, can be fitted.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a drilling type freezing pipe and a ground freezing method. [Background technology]

[0002] The ground freezing method has been known for some time. In the ground freezing method, a hole is usually drilled in the ground with a drilling rod, and then a freezing pipe is inserted into the hole drilled by the drilling rod. In the ground freezing method, the ground is frozen with the freezing pipe, and then construction work is carried out on the ground.

[0003] Patent Document 1 describes a freezing pipe used in a ground freezing method. In the ground freezing method of Patent Document 1, a technique is proposed in which a drilling rod is used to drill a hole in the ground, and then the drilling rod is made to function as a freezing pipe.

[0004] Here, when drilling holes in the ground using a drilling rod, it is necessary to drill the holes while discharging drilling water. For this reason, the drilling rod of Patent Document 1 is provided with a valve mechanism at the tip of the boring head that opens under the pressure of drilling water but closes under the supply pressure of cooling liquid. As a result, when the drilling type freezing pipe is used as a drilling rod, drilling water can be discharged from the tip of the boring head, and when used as a freezing pipe, cooling liquid can be circulated inside the freezing pipe. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-82049 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, the valve mechanism in Patent Document 1 is configured to close at the supply pressure of the cooling liquid. However, when the pressure inside the freezing tube increases during the supply of cooling liquid from the refrigerant header to the freezing tube, the valve mechanism opens, causing the cooling liquid to leak.

[0007] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a drilling-type freezing pipe that not only allows drilling while discharging drilling water from the discharge outlet, but also prevents cooling liquid from leaking from the discharge outlet even if the internal pressure increases when circulating the cooling liquid, and a ground freezing method using the same. [Means for solving the problem]

[0008] One embodiment of the present invention relates to a freezing pipe body having a base plate that seals the inside at an end in the direction of the central axis, and capable of supplying cooling liquid into the space inside the base plate, a drilling bit provided at the tip of the end of the freezing pipe body, a communicating passage that penetrates the base plate, an outlet located outside the base plate and provided at one end of the communicating passage, a connection port located inside the base plate and provided at the other end of the communicating passage, and a water supply pipe that is located within the freezing pipe body and connected to the connection port and can supply drilling water to the outlet port, and the communicating passage has a plug insertion portion into which a plug that is passed from the connection port and blocks the communicating passage can be fitted.

[0009] A ground freezing method according to one embodiment of the present invention comprises an embedding step of embedding the above-mentioned drilling type freezing pipe into the ground, a plug insertion step of passing a rod holding the plug at its tip through the water pipe after the embedding step and fitting the plug into the plug insertion portion, and a freezing step of supplying cooling liquid to the freezing pipe body. Effect of the Invention

[0010] The above-mentioned aspects of the drilling type freezing pipe and ground freezing method of the present invention not only allow drilling while discharging drilling water from the discharge outlet, but also have the advantage of preventing cooling liquid from leaking from the discharge outlet even if the internal pressure increases when circulating the cooling liquid. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a schematic cross-sectional view of a drilled-hole freezing pipe according to the present embodiment. [Diagram 2] FIG. 2 is an enlarged view of part A in FIG. [Diagram 3] FIG. 2 is a schematic cross-sectional view of the tip of the drilled-hole freezing pipe according to the present embodiment. [Figure 4] 1A is a schematic partially cutaway side view of the plug, and FIG. 1B is a schematic plan view of the plug. [Diagram 5] FIG. 2 is a schematic cross-sectional view showing how the drilling type freezing pipe according to the present embodiment is used to freeze the ground. [Figure 6] 2 is a flowchart of a ground freezing method according to the present embodiment. [Figure 7] 1A to 1D are schematic cross-sectional views for explaining the ground freezing method. [Figure 8] FIG. 4 is a schematic cross-sectional view of a joint according to a first modified example. [Figure 9] FIG. 11 is a schematic cross-sectional view of a joint according to Modification 2. [Figure 10] FIG. 11 is a schematic cross-sectional view of a joint according to Modification 3. [Figure 11] FIG. 11 is a schematic cross-sectional view of a joint according to Modification 4. [Figure 12] FIG. 11 is a schematic cross-sectional view of a joint according to Modification 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] <Embodiment> Hereinafter, the hole-drilling type freezing pipe 100 and the ground freezing method according to the present embodiment will be described with reference to the accompanying drawings.

[0013] The drilling type freezing pipe 100 according to this embodiment is used in a ground freezing method. The ground freezing method is a method in which, when carrying out underground construction work, the ground around the planned construction site is frozen to create a frozen soil wall (sometimes called a "barrier wall" or "bearing wall") to protect the planned construction site, and then construction work is carried out on the ground. Examples of ground freezing methods include a brine method and a low-temperature liquefied gas method.

[0014] The brine method is a method of cooling the ground by circulating a cooling liquid (brine) between a refrigerator installed above ground and a freezing tube inserted underground. The brine is cooled to about -30°C by the refrigerator. The low-temperature liquefied gas method is a method in which a cooling liquid (liquid nitrogen) is poured into a freezing tube, and the heat of vaporization of the liquid nitrogen is used to cool the ground. The vaporized nitrogen gas is released into the atmosphere.

[0015] In this way, regardless of which method is used as the ground freezing method, a coolant is supplied to the drilling type freezing pipe 100. For convenience of explanation, the following will be described using the brine method as an example of the ground freezing method.

[0016] After drilling the ground, the drilling type freezing pipe 100 can freeze the ground by supplying a cooling liquid to the pipe without being pulled out of the ground. As shown in FIG. 1, the drilling type freezing pipe 100 includes a freezing pipe body 1, a drilling bit 2, a nozzle 3 having a discharge port 31, a connection port portion 4 having a connection port 41, and a water supply pipe 5 connected to the connection port 41. When the cooling liquid is supplied, the drilling type freezing pipe 100 further includes a plug 6 for closing the connection port portion 4 and a supply pipe 7, as shown in FIG. 5. In this embodiment, the drilling type freezing pipe 100 is embedded so as to be perpendicular to the ground, but may be embedded at an angle to the ground. The drilling type freezing pipe 100 may be embedded in the horizontal ground or in a slope inclined to the horizontal plane.

[0017] In the following, for ease of explanation, the direction in which the drilling type freezing pipe is inserted into the ground will be referred to as the "central axis direction", and in the central axis direction, the drilling bit side will be referred to as the "underground side" and the opposite side will be referred to as the "surface side".

[0018] In addition, in this specification, "parallel" refers not only to two straight lines, surfaces, etc. (hereinafter referred to as "straight lines") that do not intersect even when extended, but also to two straight lines, etc. that intersect at an angle of 10° or less. Furthermore, "orthogonal" refers to two straight lines, etc. that intersect at an angle of 90°±10°. However, even if two straight lines, etc. do not intersect directly, if they intersect when extended, they are included in the term "orthogonal."

[0019] (Freezing tube body 1) The freezing pipe body 1 constitutes the main body of the drilling type freezing pipe 100. The freezing pipe body 1 is hollow, and is constructed by connecting a plurality of divided pipes 11 with joints 12 along the central axis of the freezing pipe body 1. The freezing pipe body 1 is provided with a base plate 16 that seals the inside of the freezing pipe body 1. In this embodiment, in the central axial direction of the freezing pipe body 1, the side of the drilling bit 2 with respect to the base plate 16 may be referred to as the "outside", and the side of the water pipe 5 with respect to the base plate 16 may be referred to as the "inside".

[0020] The substrate 16 closes the inside of the freezing pipe main body 1 at the end in the central axis direction of the freezing pipe main body 1. In this specification, "the end in the central axis direction of the freezing pipe main body 1" refers to a range from the end in the central axis direction of the freezing pipe main body 1 to a position a predetermined dimension inward. The "predetermined dimension" here means 10% of the total length of the freezing pipe main body 1. In other words, if the substrate 16 is located anywhere within a range from the end of the freezing pipe main body 1 to the predetermined dimension, it is considered to be disposed at the end in the central axis direction of the freezing pipe main body 1.

[0021] The substrate 16 divides the inside of the freezing pipe body 1. The substrate 16 intersects with the central axis of the freezing pipe body 1. The substrate 16 according to the present embodiment is perpendicular to the central axis, and divides the inside of the freezing pipe body 1 into two regions R1 and R2 aligned in the central axis direction. In the inside of the freezing pipe body 1, the region R1 inside the substrate 16 is a space through which the cooling liquid flows, and the region R2 outside the substrate 16 faces the ground when drilling. The substrate 16 is joined to the inner circumferential surface of the split pipe 11, for example, by welding. A nozzle 3 and a connection port 4, which will be described later, are attached to the substrate 16.

[0022] (split tube 11) The split pipe 11 is a pipe constituting the freezing pipe main body 1. A plurality of split pipes 11 are arranged along the central axis of the freezing pipe main body 1. The nominal thickness of the split pipe 11 is not particularly limited, but is preferably, for example, schedule 20 or more, and more preferably, schedule 40. The diameter of the split pipe 11 is not particularly limited, but is preferably, for example, 65A or more and 150A or less, and more preferably, 80A or more and 125A or less. The material of the split pipe 11 is not particularly limited, and examples thereof include carbon steel pipes for piping, stainless steel pipes, and alloy steel pipes. The split pipes 11 adjacent to each other in the central axis direction are connected by joints 12 as shown in FIG. 1.

[0023] (Joint 12) The joint 12 connects the ends of adjacent split pipes 11 to form a straight freezing pipe main body 1 extending along the central axis. As shown in Fig. 2, the joint 12 includes an outer cylinder 13, an inner cylinder 14, and a watertight portion. In this embodiment, a plurality of seal members 151 are used as the watertight portion, but as shown in a modified example described later, the joint 12 may have a structure in which water is stopped by pressure welding between metals.

[0024] (Outer cylinder 13) The outer cylinder body 13 is connected to one end of the split pipe 11 in the central axis direction. The outer cylinder body 13 is formed in a cylindrical shape. The outer cylinder body 13 includes an inner fitting portion 131 and a connected portion 132. The inner fitting portion 131 and the connected portion 132 are formed integrally. Here, the outer cylinder body 13 according to this embodiment is connected to the split pipe 11 on the ground surface side of the adjacent split pipes 11, but may also be connected to the split pipe 11 on the underground side.

[0025] The internal fitting portion 131 is fitted into the end of the split pipe 11 and fixed to the end. The internal fitting portion 131 is fixed by welding in a state where it is fitted into the inner periphery of the end of the split pipe 11. It is preferable that the outer diameter of the internal fitting portion 131 is approximately the same as the inner diameter of the split pipe 11. The split pipe 11 and the internal fitting portion 131 are connected at the time of shipment from the factory or by work on site, but it is preferable that this be done in advance at the time of shipment from the factory.

[0026] The connected portion 132 is a portion of the outer cylinder 13 into which the inner cylinder 14 is fitted. When the inner cylinder 14 is fitted into the outer cylinder 13, the inner circumferential surface of the connected portion 132 faces the outer circumferential surface of the inner cylinder 14. The connected portion 132 extends from the inner fitting portion 131 along the central axis of the freezing pipe main body 1. As a result, the connected portion 132 is located between adjacent split pipes 11 in the central axial direction of the freezing pipe main body 1.

[0027] The connected part 132 has the part with the largest outer diameter of the outer cylinder body 13. In this embodiment, the connected part 132 protrudes radially outward from the outer circumferential surface of the inner fitted part 131. That is, the outer diameter of the connected part 132 is larger than the outer diameter of the inner fitted part 131. On the other hand, the outer diameter of the connected part 132 is formed to be equal to or smaller than the outer diameter of the split pipe 11. It is preferable that the outer diameter of the connected part 132 is located within the wall thickness of the split pipe 11 in the diameter direction of the split pipe 11, and more preferably, the outer diameter of the connected part 132 is the same as the outer diameter of the split pipe 11.

[0028] In this specification, "the outer diameter of the connected part 132 is the same as the outer diameter of the split pipe 11" includes an error of ±2% of the outer diameter of the connected part 132. In other words, it includes not only the case where the outer surface of the connected part 132 and the outer surface of the split pipe 11 are flush (on the same plane), but also the case where the outer surfaces are misaligned in the radial direction as long as it is within ±5% of the outer diameter. Similarly, "the outer diameter of the connected part 132 is equal to or smaller than the outer diameter of the split pipe 11" means that the outer diameter of the connected part 132 is equal to or smaller than the outer diameter of the split pipe 11. "Equivalent" means a range that can be considered to be technically the same. Therefore, for example, even if the outer diameter of the connected part 132 is larger than the outer diameter of the split pipe 11 by within +5%, it is still considered to be in the category of "the outer diameter of the connected part 132 is equal to or smaller than the outer diameter of the split pipe 11."

[0029] The connected portion 132 has a threaded portion (hereinafter referred to as "outer cylinder threaded portion 133") that is screwed into the inner cylinder 14. The outer cylinder threaded portion 133 is a female thread formed on the inner peripheral surface of the opening of the connected portion 132. The outer cylinder threaded portion 133 is located closer to the opening end of the connected portion 132 than the seal material 151 is. There are no particular limitations on the outer cylinder threaded portion 133, and examples of the threaded portion include a triangular thread, a trapezoidal thread, and a square thread.

[0030] A plurality of recesses 15 to which a sealing material 151 is attached are formed on the inner peripheral surface of the connected portion 132. The recesses 15 are formed in an annular shape centered on the central axis of the connected portion 132, and the plurality of recesses 15 are arranged at intervals in the central axial direction of the connected portion 132.

[0031] (Inner cylinder 14) The inner cylinder body 14 is attached to one of the adjacent split pipes 11 opposite to the split pipe 11 to which the outer cylinder body 13 is attached. The inner cylinder body 14 is formed in a cylindrical shape. The inner cylinder body 14 includes an inner fitting portion 141 and a connection portion 143. The inner fitting portion 141 and the connection portion 143 are formed integrally.

[0032] The internal fitting portion 141 is fitted into the end of the split pipe 11 and fixed to the end. The internal fitting portion 141 is fixed by welding in a state where it is fitted into the inner periphery of the end of the split pipe 11. It is preferable that the outer diameter of the internal fitting portion 141 is approximately the same as the inner diameter of the split pipe 11. The connection between the split pipe 11 and the internal fitting portion 141 is performed at the time of shipment from the factory or by work on site, as with the outer cylindrical body 13, but it is preferable that this be performed in advance at the time of shipment from the factory.

[0033] At least a part of the inner peripheral surface of the inner cylinder 14 is tapered in the central axis direction of the freezing pipe main body 1 so that the diameter becomes smaller as it goes from the underground side to the ground surface side. The tapered surface included in the inner peripheral surface of the inner cylinder 14 is called a "tapered surface 142". The angle between the tapered surface 142 and the inner peripheral surface of the split pipe 11 is, for example, 20° to 45°, more specifically, 25° to 40°. However, these are only examples. In this way, it is possible to suppress the flow of the cooling liquid from being stagnated in the joint 12. In addition, a tapered surface can also be formed on the inner peripheral surface of the inner fitting portion 131 of the outer cylinder 13. This reduces catching when inserting the supply pipe 7 into the freezing pipe main body 1, and allows for smooth insertion.

[0034] The connecting part 143 is detachably connected to the connected part 132 of the outer cylinder body 13. The connecting part 143 extends from the inner fitting part 141 along the central axis of the freezing pipe main body 1. The connecting part 143 is located between adjacent split pipes 11. When the connecting part 143 is connected to the connected part 132, it is fitted into the inner periphery of the connected part 132 and overlaps concentrically with the connected part 132 radially inward.

[0035] A threaded portion (hereinafter referred to as an inner cylinder threaded portion 144) is formed at the base end of the outer circumferential surface of the connecting portion 143. The inner cylinder threaded portion 144 is a male screw that is screwed into the outer cylinder threaded portion 133. The outer cylinder 13 and the inner cylinder 14 are joined to each other by screwing the inner cylinder threaded portion 144 into the outer cylinder threaded portion 133.

[0036] (Sealant 151) The sealing material 151 is disposed between the inner peripheral surface of the outer cylinder body 13 and the outer peripheral surface of the inner cylinder body 14. Specifically, the sealing material 151 is disposed in the recess 15. Since the sealing material 151 is disposed between the inner peripheral surface of the outer cylinder body 13 and the outer peripheral surface of the inner cylinder body 14, a surface with high processing accuracy can be made to be the opposing surface of the sealing material 151, making it easier to exhibit waterproofing performance.

[0037] The seal material 151 is formed between the outer cylinder 13 and the inner cylinder 14 over the entire length around the central axis of the freezing pipe main body 1. That is, the seal material 151 is ring-shaped. Examples of the seal material 151 include an O-ring, an X-ring (twister ring), a square ring with a square cross section, and a hollow ring with a doughnut cross section. Examples of the material of the seal material 151 include cold-resistant rubber such as elastomer, soft resin, and urethane. Examples of the elastomer include silicone rubber, fluororubber, urethane rubber (thermosetting elastomer), and natural rubber. The seal material 151 according to this embodiment is an O-ring made of elastomer.

[0038] The multiple sealing materials 151 are arranged at intervals along the central axis of the freezing pipe main body 1. The interval L1 between adjacent sealing materials 151 may be a distance that prevents the sealing materials 151 from interfering with each other. Although it is preferable to have multiple sealing materials 151, a single sealing material will suffice. However, by having multiple sealing materials 151, it is possible to prevent loss of liquid-tightness even if one sealing material 151 is damaged during construction.

[0039] (Drilling Bit 2) As shown in Fig. 3, a drilling bit 2 is provided at the tip of the underground end in the central axial direction of the freezing pipe main body 1. The drilling bit 2 is a tool for drilling holes in the ground. In this embodiment, the drilling bit 2 is a cylindrical drilling bit 2 having a plurality of blades 21, and is joined to the tip of the split pipe 11 by, for example, welding. The plurality of blades 21 are formed at a constant pitch in the circumferential direction around the central axis.

[0040] The drilling bit 2 is not particularly limited, and examples thereof include a wedge bit, a button bit, a cutting bit, a diamond bit, a roller cone bit, a disk bit, etc. It is preferable that the drilling bit 2 is appropriately selected according to the hardness and type of the ground.

[0041] (Nozzle 3) During drilling, the nozzle 3 discharges drilling water from the discharge port 31. The nozzle 3 has at least one discharge port 31. The discharge port 31 according to this embodiment is configured by an open end on the underground side in the central axis direction.

[0042] The nozzle 3 protrudes from the outer surface of the substrate 16 along the central axis direction. The nozzle 3 is attached so that the inside thereof communicates with a through hole 161 formed in the substrate 16. This allows the through hole 161 of the substrate 16 and the outlet 31 of the nozzle 3 to communicate with each other.

[0043] The nozzle 3 preferably has a check valve 32. The check valve 32 can reduce the inflow of groundwater from the discharge port 31 into the region R1 during excavation. The check valve 32 according to this embodiment is a spring-type ball check valve having a valve body 321, a spring 322, and a valve seat 323, as shown in FIG.

[0044] The valve element 321 can approach and separate from the valve seat 323, and can close the flow path (communicating passage 42) leading to the discharge port 31 by contacting the valve seat 323. The valve element 321 is, for example, spherical. The spring 322 can constantly press the valve element 321 against the valve seat 323. The spring 322 presses the valve element 321 against the valve seat 323 with a predetermined force, and when the water supply pressure from the water supply pipe 5 exceeds the predetermined force, the valve element 321 is pressed outward, and the valve element 321 opens the flow path (communicating passage 42). This allows the check valve 32 to open the flow path (communicating passage 42) when water is supplied from the water supply pipe 5, and close the flow path (communicating passage 42) when the water supply from the water supply pipe 5 stops.

[0045] The check valve 32 is not limited to a ball check valve, and may be configured by other check valves such as a swing check valve, a lift check valve, or a wafer check valve.

[0046] (Connection port 4) The connection port 4 is provided on the inside of the substrate 16, and communicates with the discharge port 31 through a communication passage 42. The connection port 4 protrudes inward along the central axis direction from the inner surface (inner face) of the substrate 16. The connection port 4 is cylindrical, and is attached to the through hole 161 of the substrate 16 so that its inside communicates with the through hole 161 of the substrate 16. This allows the inside of the connection port 4 to communicate with the through hole 161 of the substrate 16.

[0047] The communication passage 42 is a flow path that connects an opening on the inside of the connection port portion 4 (hereinafter referred to as “connection port 41”) and the discharge port 31. The connection port 41 communicates with the discharge port 31 via the communication passage 42 by attaching the connection port portion 4 to the through hole 161. The communication passage 42 is constituted by the inside of the connection port portion 4, the through hole 161, and the inside of the nozzle 3.

[0048] A water supply pipe connecting part 43 is formed in the connection port 4. The water supply pipe connecting part 43 is formed so as to be recessed outward in the central axis direction from the connection port 41 of the connection port 4. A thread is formed on the inner peripheral surface of the water supply pipe connecting part 43. The water supply pipe 5 is removably connected to the connection port 41 by being screwed into the water supply pipe connecting part 43.

[0049] The connection port 4 has a plug insertion portion 44 into which a plug 6 is fitted. As shown in Fig. 5, the plug 6 is fitted into the plug insertion portion 44 to close the communication passage 42. The plug 6 is passed through the connection port 41 inside the freezing pipe main body 1 and fitted into the plug insertion portion 44. In this embodiment, the plug insertion portion 44 is formed in the connection port 4, but may be formed in the through hole 161 or the nozzle 3, or may be formed across the connection port 4, the through hole 161, and the nozzle 3.

[0050] The plug insertion portion 44 is formed along the central axis direction of the freezing pipe main body 1 from the inner surface of the water supply pipe connection portion 43. The plug insertion portion 44 is formed between the water supply pipe connection portion 43 and the through hole 161. A threaded portion (hereinafter referred to as "insertion portion threaded portion 441") that meshes with the threads formed on the outer peripheral surface of the plug 6 is formed on the inner peripheral surface of the plug insertion portion 44.

[0051] As shown in Fig. 4, the plug 6 is formed in a substantially cylindrical shape. The plug 6 includes a water-stopping portion 61 formed at the tip of the plug body, a screw (hereinafter referred to as "plug screw 62"), and a swivel hole 63. The plug 6 is preferably made of a magnetic material, which allows it to be magnetically attached to the rod 8 described below.

[0052] The water stopping portion 61 is a portion facing the inner circumferential surface of the communicating passage 42. The water stopping portion 61 has a plurality of grooves 611 formed at regular intervals in the central axis direction. A water stopping material 612 is disposed in the groove 611, and the water stopping material 612 is in close contact with the inner circumferential surface of the communicating passage 42. As a result, when the plug 6 is fitted into the plug insertion portion 44, the communicating passage 42 is airtightly closed. Examples of the water stopping material 612 include an O-ring, an X-ring (twister ring), a square ring with a square cross section, and a hollow ring with a doughnut cross section.

[0053] Since the water stop portion 61 has a plurality of grooves 611 formed therein spaced apart in the central axis direction, the water stop material 612 at the most distal end (underground side) removes dirt and dust adhering to the inner circumferential surface of the communicating passage 42, thereby enabling the second and subsequent stages of water stop materials 612 to come into close contact with the inner circumferential surface of the communicating passage 42. This allows the plug 6 to reliably close the communicating passage 42.

[0054] The plug thread 62 is formed on the outer circumferential surface of the plug body. The plug thread 62 meshes with the insertion portion thread portion 441 of the plug insertion portion 44. By forming the plug thread 62 on the plug 6, even if there is a high degree of adhesion between the water-stopping material 612 and the inner circumferential surface of the communication passage 42, the plug 6 can be rotated about the central axis as the rotation axis and screwed into the plug insertion portion 44. The plug thread 62 is preferably located on the ground surface side of the water-stopping portion 61 in the central axis direction, but may be located underground on the ground side of the water-stopping portion 61 in the central axis direction.

[0055] The swirl hole 63 is formed in the end surface of the plug body on the ground surface side. The tip of a rod 8 described below is fitted into the swirl hole 63, and the plug 6 is rotated around the central axis by the rod 8. Examples of the swirl hole 63 include a square hole, a hexagonal hole, and a cross hole.

[0056] The outer diameter of the plug 6 is smaller than the inner diameter of the water supply pipe 5. This allows the plug 6 to be inserted through the water supply pipe 5, pass through the connection port 41, and fit into the plug insertion portion .

[0057] (water pipe 5) 3, the water supply pipe 5 is disposed in the freezing pipe body 1 and connected to the connection port 41. The inside of the water supply pipe 5 communicates with the discharge port 31. The water supply pipe 5 is connected to a water supply pump and can supply drilling water toward the discharge port 31.

[0058] The water supply pipe 5 is preferably removably connected to the connection port 41. A thread 51 is formed at the end of the water supply pipe 5 on the underground side in the central axis direction. The thread 51 of the water supply pipe 5 engages with the water supply pipe connection part 43 of the connection port 41, so that the water supply pipe 5 is removably connected to the connection port 41. However, the connection between the connection port 41 and the water supply pipe 5 is not limited to a threaded type, and may be realized, for example, by providing a protrusion protruding radially outward on the outer circumferential surface of the end of the water supply pipe 5 and providing an L-shaped groove through which the protrusion passes on the inner circumferential surface of the connection port 41, so that the protrusion and part of the groove are engaged, or may be a fitting type.

[0059] (Supply pipe 7) As shown in Fig. 5, a supply pipe 7 for supplying a cooling liquid is inserted inside the freezing pipe main body 1. The tip of the supply pipe 7 is separated from the upper surface of the substrate 16. In this embodiment, the supply pipe 7 and the freezing pipe main body 1 are arranged concentrically, but they do not have to be arranged concentrically. For example, the supply pipe 7 may be located at a position deviated from the central axis of the freezing pipe main body 1. In addition, the cross-sectional shape of the supply pipe 7 does not have to be circular, and may be, for example, an elliptical or rectangular shape.

[0060] The cooling liquid supplied to the supply pipe 7 from a brine header (not shown) connected to the refrigerator flows out from the tip opening of the supply pipe 7, passes between the supply pipe 7 and the freezing pipe body 1, enters the brine header, and returns to the refrigerator. This allows the cooling liquid to circulate between the refrigerator and the drilled type freezing pipe 100, and the soil around the drilled type freezing pipe 100 can be cooled.

[0061] (ground freezing method) Next, an example of a ground freezing method using the above-described drilling type freezing pipe 100 will be described. As shown in Fig. 6, the ground freezing method according to this embodiment performs an embedding step S1, a plug insertion step S2, a watertightness checking step S3, a water pipe removal step S4, and a freezing step S5 in this order, and then performs work on the ground S6.

[0062] The embedding step S1 is a process of embedding the hole-drilling type freezing pipe 100 according to this embodiment in the ground. In the embedding step S1, for example, the hole-drilling type freezing pipe 100 is inserted into the ground while rotating about its central axis using a full-circle rotation device. The hole-drilling type freezing pipe 100 has a drilling bit 2 at the end in the central axis direction, so that it can be inserted into the ground.

[0063] In the burying step S1, it is preferable to insert the multiple split pipes 11 into the ground while joining them together with the joints 12. This makes it easier to embed the hole-drilling type freezing pipe 100 compared to inserting the split pipes 11 into the ground while joining them together by welding. In the ground freezing method according to this embodiment, after the hole-drilling type freezing pipe 100 is embedded in the burying step S1, it is left in the ground as it is without being pulled out.

[0064] Next, a plug insertion step S2 is performed. In the plug insertion step S2, after the embedding step S1, as shown in Fig. 7(A), a rod 8 holding a plug 6 at its tip is used to fit the plug 6 into the plug insertion part 44. As shown in Fig. 7(A), the rod is rod-shaped and the maximum dimension in the cross section is smaller than the inner diameter of the water supply pipe 5. The rod 8 according to this embodiment is a rod with a circular cross section and its outer diameter is smaller than the inner diameter of the water supply pipe 5.

[0065] The rod 8 has a plug holding portion 81. The plug holding portion 81 is formed at the end of the rod 8 on the underground side in the central axial direction. The plug holding portion 81 includes a fitting portion that fits into the swirl hole 63 of the plug 6, and a magnet portion. The plug holding portion 81 can hold the plug 6 by the magnet portion magnetically attracting the plug 6 and the fitting portion fitting into the swirl hole 63 of the plug 6.

[0066] The fitting portion may have any shape as long as it fits into the swivel hole 63, and examples of such shapes include a square cross section, a hexagonal cross section, and a cross cross section.

[0067] In the plug insertion step S2, the worker uses the rod 8 holding the plug 6 by the plug holding portion 81 to insert the rod 8 together with the plug 6 into the water pipe 5. As shown in FIG. 7(B), the worker inserts the plug 6 into the plug insertion portion 44 and rotates the rod 8 about its central axis as a rotation axis, whereby the plug screw 62 of the plug 6 is screwed into the insertion portion threaded portion 441 of the plug insertion portion 44, and the plug 6 can be fitted into the plug insertion portion 44. Thereafter, the worker pulls the rod 8 toward the ground surface in the central axis direction, whereby the plug holding portion 81 is detached from the plug 6, and the rod 8 can be pulled out of the water pipe 5.

[0068] The plug holding portion 81 does not necessarily have to have a magnet portion. The magnet portion may be provided on the plug 6.

[0069] Next, the worker executes a watertightness confirmation step S3. The watertightness confirmation step S3 is a process of using the water pipe 5 to confirm whether the plug 6 is watertightly fitted into the plug insertion portion 44. In the watertightness confirmation step S3, the worker can, for example, apply air pressure to the inside of the water pipe 5, measure the air pressure, and determine that the plug 6 is watertightly fitted if the air pressure is not reduced for a certain period of time. Note that, if the water pipe 5 extends in the vertical direction, liquid may be poured into the water pipe 5, the liquid level of the liquid may be measured, and it may be determined that the plug 6 is watertightly fitted if the liquid level does not decrease for a certain period of time.

[0070] This shows that the plug 6 is fitted into the plug insertion portion 44 in a watertight manner, and it can be confirmed that even if coolant is circulated inside the drilled type freezing pipe 100, no leakage of coolant will occur from the connecting passage 42.

[0071] Next, the worker executes the water pipe removal step S4. The water pipe removal step S4 is a process of removing the water pipe 5 from the connection port 41. In the water pipe removal step, as shown in FIG. 7(D), the worker rotates the water pipe 5 around the central axis as the rotation axis to remove the water pipe 5 from the connection port 41. Since the watertightness confirmation step S3 confirms that the plug 6 is fitted into the plug insertion part 44 in a watertight state, the watertightness of the inside of the freezing pipe main body 1 is reliably ensured even if the water pipe 5 is removed. By removing the water pipe 5, the inside of the freezing pipe main body 1 can be secured widely, so that even if leakage of the cooling liquid occurs in the freezing pipe main body 1, it is easy to deal with it by inserting a small-diameter pipe inside, and the cooling capacity can be improved. Furthermore, the insertion space of a measuring instrument for checking the bending of the freezing pipe main body 1 can be appropriately secured.

[0072] Next, the worker performs the freezing step S5. The freezing step S5 is a process of supplying a cooling liquid to the freezing pipe body 1. In the freezing step S5, the worker inserts the supply pipe 7 into the drilled type freezing pipe 100 buried in the ground, and supplies a cooling liquid from a brine header (not shown) connected to a refrigerator to the supply pipe 7. This allows the cooling liquid to circulate between the refrigerator and the drilled type freezing pipe 100, and the soil around the drilled type freezing pipe 100 can be cooled.

[0073] <Modification> The above embodiment is merely one of various embodiments of the present invention. The embodiment can be modified in various ways depending on the design, etc., as long as the object of the present invention can be achieved. Modifications of the embodiment are listed below. The modifications described below can be applied in appropriate combination.

[0074] (Variation 1) In the bore-drilled freezing pipe 100 according to the above embodiment, the joint 12 has the sealant 151 as a watertight portion provided on the inner circumferential surface of the outer cylindrical body 13, but as shown in Fig. 8, it may be provided on the outer circumferential surface of the inner cylindrical body 14. The sealant 151 is disposed in a recess 15 formed on the outer circumferential surface of the inner cylindrical body 14. Furthermore, the sealant 151 is located on the opening surface side of the inner cylindrical body 14 with respect to the inner cylindrical body thread portion 144.

[0075] (Variation 2) In the joint 12 according to the above embodiment, the outer cylinder 13 includes an inner fitting portion 131 and a connected portion 132, and the inner fitting portion 131 is fitted into the split pipe 11, but as shown in Fig. 9, the inner fitting portion 131 may be omitted. That is, the outer cylinder 13 may be connected to the freezing pipe main body 1 by butt welding. In addition, in this modification 2, the inner cylinder 14 has an inner fitting portion 141, but the inner fitting portion 141 may be omitted as long as the joint strength with the split pipe 11 can be ensured.

[0076] (Variation 3) In the joint 12 according to the above embodiment, the seal material 151 is located closer to the opening surface than the inner cylinder threaded portion 144 of the inner cylinder 14 in the central axial direction, but as shown in Fig. 10, the seal material 151 may be located closer to the base end portion than the inner cylinder threaded portion 144 in the inner cylinder 14. In other words, the watertight portion may be provided on either side in the central axial direction with respect to the inner cylinder threaded portion 144 or the outer cylinder threaded portion 133, as long as it is provided so as to be aligned in the central axial direction.

[0077] (Variation 4) In the joint 12 according to the above embodiment, the ends of the multiple split pipes 11 are connected together by connecting the outer cylinder 13 and the inner cylinder 14 with the threaded portions 144, 133, but as shown in Fig. 11, the joint 12 and the split pipes 11 may be connected with the threaded portions 112, 133. In this case, a female threaded portion 112 and a seal material facing surface 111 are formed on the inner circumferential surface of the split pipe 11. The seal material facing surface 111 is a surface that exhibits watertightness by coming into contact with a seal material 151, and is surface-treated to reduce surface roughness.

[0078] In the joint 12, the part with the largest outer diameter is disposed between the pair of split pipes 11. It is preferable that at least a pair of parallel surfaces is formed on the outer peripheral surface of the part with the largest outer diameter of the joint 12. In this way, the outer peripheral surface can be held with a tool such as a wrench, and the joint 12 can be rotated around the central axis. The joint 12 has an inner cylinder threaded portion 144 and a watertight portion (here, a pair of seal members 151) on each side in the central axis direction. The seal members 151 are crushed by the seal member opposing surfaces 111, thereby achieving watertightness.

[0079] (Variation 5) In the joint 12 according to the above embodiment, a plurality of seals 151 are provided as the watertight portion, but watertightness may be ensured by contact between abutting surfaces, for example, as shown in Fig. 12. The joint 12 includes a first connection part 17 connected to the split pipe 11, a cap nut 19 rotatably attached to the first connection part 17, and a second connection part 18 connected to the first connection part 17 by being screwed in by the cap nut 19.

[0080] The cap nut 19 has an outer cylinder threaded portion 133 (female thread) formed on its inner circumferential surface. The second connecting portion 18 has an inner cylinder threaded portion 144 (male thread) formed on its outer circumferential surface at its tip. The outer corner of the tip surface of the second connecting portion 18 (hereinafter, abutting surface 181) is tapered with respect to the central axis. The inner corner of the tip surface of the first connecting portion 17 (hereinafter, abutting surface 171) is tapered with respect to the central axis. When the outer cylinder threaded portion 133 of the cap nut 19 is screwed into the inner cylinder threaded portion 144 of the second connecting portion 18, the first connecting portion 17 and the second connecting portion 18 are connected, and the abutting surfaces 181 and 171 are pressed against each other. This configuration prevents leakage from between the first connecting portion 17 and the second connecting portion 18. In this embodiment, the portion of the joint 12 with the largest outer diameter is included in the cap nut 19.

[0081] The first connecting portion 17, the cap nut 19, and the second connecting portion 18 are made of metal, but may be made of, for example, synthetic resin, ceramic, carbon, or the like. The abutting surface 181 of the second connecting portion 18 is a tapered surface formed at an outer corner, but may be, for example, a tapered surface formed at an inner corner. In this case, the abutting surface 171 of the first connecting portion 17 is a tapered surface formed at an outer corner. The part of the joint 12 with the largest outer diameter is not limited to the cap nut 19, and may be included in the first connecting portion 17 and / or the second connecting portion 18, or may be included in all of the cap nut 19, the first connecting portion 17, and the second connecting portion 18.

[0082] (Other variations) In the above embodiment, the embodiment has been described in which the hole-drilling type freezing pipe 100 is embedded in the ground. However, for example, the hole-drilling type freezing pipe 100 may be embedded from the inner wall of an underground tunnel.

[0083] In the above embodiment, the plug 6 has a plug screw 62, the plug insertion portion 44 has an insertion portion screw portion 441, and the plug screw 62 is screwed into the insertion portion screw portion 441, but the plug 6 does not have to be fitted into the plug insertion portion 44 by a screw, and may be fitted into the plug insertion portion 44 by simple fitting.

[0084] <Summary> As described above, the first embodiment of the drilling type freezing pipe 100 includes a freezing pipe body 1 having a base plate 16 that closes the inside at the end in the central axis direction and capable of supplying a cooling liquid into the space inside the base plate 16, a drilling bit 2 provided at the tip of the end of the freezing pipe body 1, a communication passage 42 penetrating the base plate 16, a discharge port 31 arranged outside the base plate 16 and provided at one end of the communication passage 42, a connection port 41 arranged inside the base plate 16 and provided at the other end of the communication passage 42, and a water supply pipe 5 arranged in the freezing pipe body 1 and connected to the connection port 41, capable of supplying drilling water to the discharge port 31. The communication passage 42 has a plug insertion portion 44 into which a plug 6 that is passed from the connection port 41 and closes the communication passage 42 can be fitted.

[0085] According to this embodiment, when drilling, drilling water can be discharged from the discharge port 31 by supplying water from the water supply pipe 5, and when freezing the ground, the plug 6 can be fitted into the plug insertion part 44 of the communication passage 42 to circulate the cooling liquid inside the freezing pipe body 1. Since the plug 6 can be fitted into the plug insertion part 44 through the connection port 41, after the drilling is completed, the worker can firmly fit the plug 6 into the plug insertion part 44. Therefore, according to the drilling type freezing pipe 100 of this embodiment, not only can drilling be performed while discharging drilling water from the discharge port 31, but also, when circulating the cooling liquid, leakage of the cooling liquid from the discharge port 31 can be prevented even if the internal pressure increases.

[0086] In the first embodiment of the drilled-hole freezing pipe 100 according to the second aspect, the connection port 41 is removably connected to the water pipe 5. According to this embodiment, the inside of the freezing pipe body 1 can be secured widely by removing the water pipe 5. Therefore, in the unlikely event that a leakage of the cooling liquid occurs in the freezing pipe body 1, it is easy to deal with the problem by inserting a small-diameter pipe inside, and the cooling capacity can be improved. Furthermore, a space for inserting a measuring device for checking the bending of the freezing pipe body 1 can be appropriately secured.

[0087] In the hole-drilled freezing pipe 100 according to the third aspect, in the first or second aspect, the plug insertion portion 44 has a threaded portion (insertion portion threaded portion 441) that meshes with a thread (plug thread 62) formed on the outer circumferential surface of the plug 6. According to this aspect, even if the plug 6 is firmly fitted into the plug insertion portion 44, the plug 6 can be securely fitted into the plug insertion portion 44.

[0088] In the fourth aspect of the drilling type freezing pipe 100, in any one of the first to third aspects, the freezing pipe body 1 has a plurality of split pipes 11 and joints 12 connecting adjacent ends of the plurality of split pipes 11, and is formed so that the outer diameter of the largest outer diameter part of the joints 12 is equal to or smaller than the outer diameter of the split pipes 11. According to this aspect, the drilling type freezing pipe 100 can be buried deep in the ground, and since no part of the joints 12 protrudes from the outer surface of the split pipes 11, the resistance caused by the joints 12 during drilling can be reduced.

[0089] In the fifth embodiment of the drilled-hole freezing pipe 100, the joint 12 in the fourth embodiment has an outer cylinder 13 connected to one end of the split pipe 11, and an inner cylinder 14 connected to the end of the other split pipe 11 adjacent to the one end of the split pipe 11, fitted into the outer cylinder 13, and connected to the outer cylinder 13 by a screw 51, and the outer cylinder 13 includes the part with the largest outer diameter of the joint 12. According to this embodiment, the joint 12 having the outer cylinder 13 and the inner cylinder 14 can be used to join the drilled-hole freezing pipe 100 while ensuring liquid-tightness regardless of the skill of the worker.

[0090] The ground freezing method according to the sixth aspect includes an embedding step S1 of embedding the hole-drilling type freezing pipe 100 of any one of the first to fifth aspects in the ground, a plug insertion step S2 of passing a rod 8 having a plug 6 at its tip through a water pipe 5 and fitting the plug 6 into the plug insertion part 44 after the embedding step S1, and a freezing step S5 of supplying a cooling liquid to the freezing pipe body 1. According to this aspect, the ground freezing method can be performed using the hole-drilling type freezing pipe 100.

[0091] The ground freezing method according to the seventh aspect, in the sixth aspect, further includes a watertightness confirmation step S3, after the plug insertion step S2 and before the freezing step S5, for confirming whether the plug 6 is watertightly fitted into the plug insertion portion 44 by utilizing the inside of the water pipe 5. According to this aspect, fitting the plug 6 into the plug insertion portion 44 can reliably confirm that the communication passage 42 is closed, so that leakage of the coolant through the communication passage 42 can be reliably prevented. [Explanation of symbols]

[0092] 100 Drilling type cryotube 1 Freezing tube body 11 Split tube 12 Joints 13 External cylinder 131 Internal fitting part 132 Connected Part 14 Inner cylinder 141 Internal fitting part 16 Substrate 2 Drill Bits 31 Discharge port 4 Connection port 41 Connection port 42 Communication path 44 Plug insertion part 441 Insertion thread 5 Water pipe 6 Plug 61 Water stop section 62 Plug screw

Claims

1. a freezing tube body having a base plate that closes the inside of the freezing tube body at an end portion in a central axis direction, and capable of supplying a cooling liquid into a space inside the base plate; A drilling bit provided at the tip of the end of the freezing pipe body; A communication passage penetrating the substrate; a discharge port disposed outside the substrate and provided at one end of the communication passage; a connection port disposed on the inner side of the substrate and provided at the other end of the communication passage; a water supply pipe that is disposed within the freezing pipe body and connected to the connection port and capable of supplying drilling water to the discharge port; Equipped with the communication passage has a plug insertion portion into which a plug that is passed through the connection port and closes the communication passage can be fitted, Drilling type freezing tube.

2. The water supply pipe is removably connected to the connection port. The drilled freezing pipe according to claim 1.

3. The plug insertion portion has a threaded portion that meshes with a thread formed on an outer circumferential surface of the plug. The drilled-hole freezing pipe according to claim 1 or 2.

4. The freezing tube body is A plurality of split tubes; a joint connecting adjacent ends of the plurality of split pipes; having The outer diameter of the largest outer diameter portion of the joint is formed to be equal to or smaller than the outer diameter of the split pipe. The drilled-hole freezing pipe according to claim 1 or 2.

5. The joint is an outer cylinder connected to one end of the split pipe; an inner cylinder body connected to an end of another split pipe adjacent to the one end of the split pipe, fitted into the outer cylinder body, and connected to the outer cylinder body by a screw; having The outer cylinder includes a portion of the joint with the largest outer diameter. The drilled freezing pipe according to claim 4.

6. An embedding step of embedding the drilling type freezing pipe according to claim 1 or 2 in the ground; a plug insertion step of passing a rod having the plug held at its tip end through the water pipe and fitting the plug into the plug insertion portion after the embedding step; A freezing step of supplying a cooling liquid to the freezing pipe body; Equipped with Ground freezing method.

7. After the plug insertion step and before the freezing step, a watertightness confirmation step is further provided, in which the inside of the water supply pipe is used to confirm whether the plug is fitted in the plug insertion part in a watertight state. The ground freezing method according to claim 6.

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