Ground reinforcement pipe and its construction method

Abstract

To provide a ground reinforcement pipe which enables a long ground reinforcement pipe to be driven into the ground without need of jointing partial pipes with each other that constitute part of the long ground reinforcement pipe.SOLUTION: A ground reinforcement pipe 1 can be freely inserted with a drilling rod 11. A head-part partial pipe 2 with the tip being fitted with a drill bit 12 is inserted with an intermediate-part partial pipe 3 by a telescopic mechanism. The intermediate-part partial pipe 3 is provided freely telescopically in the head-part partial pipe 2 and is engaged to be jointed when fully extended. The intermediate-part partial pipe 3 is inserted with a terminal-part partial pipe 4 by a telescopic mechanism. The terminal-part partial pipe 4 is provided freely telescopically in the intermediate-part partial pipe 3 and is engaged to be jointed when fully extended.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a ground reinforcing pipe used for reinforcing the ground in long-length pre-supporting works, mirror reinforcement works, etc., and a construction method thereof. [Background technology]

[0002] Conventionally, in tunnel excavation work, auxiliary construction methods have been used, such as long forepiling work, in which, before excavating in front of the face, a long ground reinforcing steel pipe made by connecting multiple steel pipes is driven diagonally upward from the front or outer periphery of the ground, and ground improvement material is injected through the driven long ground reinforcing steel pipe to improve the ground, and long mirror reinforcement work, in which a long ground reinforcing steel pipe made by connecting multiple steel pipes is driven from the face in front of the ground, and ground improvement material is injected through the driven long ground reinforcing steel pipe to improve the ground.

[0003] When carrying out long-length fore-reinforcement work or long-length mirror reinforcement work, it is common to use steel pipes about 3m long with threads on both ends, and then manually screw the steel pipes together during construction to form long ground reinforcement steel pipes. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-45637 Summary of the Invention [Problem to be solved by the invention]

[0005] In the long-length forepiling work known as the AGF method, the standard specifications for a single steel pipe to be connected are, for example, length: 3 m, diameter: 114.3 mm, and wall thickness: 6 mm, with the weight of each steel pipe being approximately 50 kg. Furthermore, the steel pipes connected in long-length reinforcement work are generally heavy steel pipes. The task of connecting such heavy steel pipes to each other with threaded connections is extremely labor-intensive and takes a long time.

[0006] Furthermore, the task of connecting heavy steel pipes to each other with threaded connections requires high levels of skill from workers, such as those involved in threading the steel pipes together and operators of drilling machines (drifters).Therefore, there is a demand for a ground reinforcement pipe that allows long lengths of ground reinforcement pipe to be driven into the ground without the need for the task of connecting steel pipes together.

[0007] The present invention has been proposed in consideration of the above-mentioned problems, and aims to provide a ground reinforcement pipe and a construction method therefor that can be driven into the ground without requiring the work of connecting the partial pipes that make up part of the long ground reinforcement pipe. [Means for solving the problem]

[0008] The ground reinforcement pipe of the present invention is a ground reinforcement pipe into which a drilling rod can be freely inserted, and is characterized in that a trailing section pipe is inserted into a leading section pipe to which a drilling bit is attached using a telescopic mechanism, and the trailing section pipe is arranged to be freely extendable and retractable relative to the leading section pipe, and when extended, they fit together to form a connected state. According to this, by drilling and driving the hole so that the drill bit pulls the leading partial pipe, the trailing partial pipe of the telescopic mechanism is pulled out from the leading partial pipe and automatically connected to the leading partial pipe. Therefore, it is possible to drive the long ground reinforcement pipe into the ground without the need to connect the partial pipes that make up part of the long ground reinforcement pipe to each other with threaded connections.

[0009] The ground reinforcement pipe of the present invention is characterized in that another subsequent section pipe is inserted into the subsequent section pipe in one or more stages using a telescopic mechanism, and the subsequent section pipes are arranged to be able to freely extend and retract with each other and are fitted together and connected when extended. According to this system, by drilling and driving the hole so that the drill bit pulls the leading pipe section, the trailing pipe sections behind the telescopic mechanism are successively pulled out from the leading pipe section and automatically connected to the leading pipe section. Therefore, even very long ground reinforcement pipes can be driven into the ground without the need to connect the trailing pipe sections to each other with threaded connections. Furthermore, the length and number of each trailing pipe section that makes up a specific length of ground reinforcement pipe can be freely set, increasing the flexibility in designing and manufacturing the ground reinforcement pipe.

[0010] The ground reinforcement pipe of the present invention is characterized in that a stopper is provided at the rear end of the terminal section pipe constituting the rearmost subsequent section pipe, which is hooked onto a centralizer provided on the guide cell of the drilling device. This allows the rear end of the terminal pipe section to be fixed in place using the centralizer of the drilling equipment, and the subsequent pipe sections can be smoothly pulled out and connected as the drilling progresses and the leading pipe section is pulled, allowing a long ground reinforcement pipe to be driven into the ground.

[0011] The ground reinforcement pipe of the present invention is characterized in that a centering ring that is formed with approximately the same outer diameter as the base of the leading section pipe and is placed on the centralizer is provided in front of the stopper. In addition, the ground reinforcement pipe of the present invention is a ground reinforcement pipe into which a drilling rod can be freely inserted, and a subsequent section pipe is inserted into a leading section pipe to which a drilling bit is attached at its tip using a telescopic mechanism, and the subsequent section pipe is freely extendable and retractable relative to the leading section pipe and fits together when extended to form a connected state, and a ring-shaped stopper is provided at the rear end of the terminal section pipe that constitutes the trailing section pipe at the rear end, which is hooked onto a centralizer provided on the guide cell of the drilling device, and the outer diameter of the stopper is larger than the outer diameter of the base of the leading section pipe, and is formed with approximately the same outer diameter as the base of the leading section pipe, and a centering ring that is placed on the centralizer is stacked in front of the stopper. This allows the centering ring to align the leading section pipe, the trailing section pipe, and the drilling rod, making it possible to carry out drilling operations in the ground and the installation of long ground reinforcement pipes into the ground smoothly and reliably.

[0012] The method for constructing a ground reinforcement pipe of the present invention is a method for constructing a ground reinforcement pipe of the present invention, characterized in that it comprises the steps of: placing the rearmost end of the ground reinforcement pipe at a predetermined position on the guide cell of a drilling device; connecting the tip of a drilling rod inserted into the ground reinforcement pipe to a drilling bit attached to the front section pipe to transmit the driving force of the drilling machine; drilling with the drilling bit while towing the front section pipe to pull out the trailing section pipe; and fitting and connecting the trailing section pipe to the front section pipe. By drilling holes so that the drill bit pulls the leading pipe section, the trailing pipe section of the telescopic mechanism can be pulled out from the leading pipe section and automatically connected to the leading pipe section. Also, it is possible to check that the trailing pipe section is properly unwound from the leading pipe section based on the length of the drill rod. [Effects of the Invention]

[0013] According to the ground reinforcement pipe or construction method of the present invention, a long ground reinforcement pipe can be driven into the ground without the need to interconnect the partial pipes that make up part of the long ground reinforcement pipe. [Brief explanation of the drawings]

[0014] [Figure 1] 1A is a front view of a ground reinforcement pipe according to a first embodiment of the present invention, FIG. 1B is a front view of the ground reinforcement pipe according to the first embodiment in an extended state, and FIG. 1C is a cross-sectional view of the ground reinforcement pipe according to the first embodiment. [Figure 2] FIG. 2 is an enlarged end view of the ground reinforcement pipe of the first embodiment. [Figure 3] 4A and 4B are process explanatory diagrams illustrating the first half of an example of the construction process for the ground reinforcement pipe of the first embodiment. [Figure 4] 5A and 5B are process explanatory diagrams illustrating the latter half of an example of the construction process for the ground reinforcement pipe of the first embodiment. [Figure 5] An explanatory diagram illustrating the long-length pre-supporting work and mirror reinforcement work in which the ground reinforcement pipe of the first embodiment is installed. [Figure 6] 1A is a front view of a ground reinforcing pipe according to a second embodiment of the present invention, and FIG. 1B is a front view of the ground reinforcing pipe according to the second embodiment in an extended state. [Figure 7] FIG. 10 is a perspective explanatory view illustrating the extension operation of the ground reinforcing pipe of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] [Ground reinforcement pipe of the first embodiment] 1 and 2, the ground reinforcement pipe 1 of the first embodiment according to the present invention is a ground reinforcement pipe 1 into which a drilling rod 11 can be freely inserted, and is composed of a leading section pipe 2 to which a drilling bit 12 is attached at its tip, an intermediate section pipe 3 which is inserted into the leading section pipe 2 using a telescopic mechanism, and a terminal section pipe 4 which is inserted into the intermediate section pipe 3 using a telescopic mechanism. The intermediate section pipe 3 and the terminal section pipe 4 each correspond to a subsequent section pipe, and the ground reinforcement pipe 1 as a whole is composed of a multi-stage telescopic mechanism. It is also possible to provide multiple intermediate section pipes 3, and insert the rearward intermediate section pipe 3 into the leading or front section pipe 3 which corresponds to the back side of the ground using a telescopic mechanism.

[0016] The leading section pipe 2 is formed in a substantially cylindrical shape and has a base section 21 formed with substantially the same outer diameter and inner diameter, a tapered section 22 whose diameter gradually decreases from the rear end of the base 21 toward the rear, and a tapered cylindrical section 23 extending rearward from the rear end of the tapered section 22 and formed with substantially the same outer diameter and inner diameter. The base 21 is formed with a discharge hole 24, which is a through hole that discharges soil improvement material into the ground surrounding the leading section pipe 2, and a drill bit 12 is attached to the tip of the base 21 via a casing shoe. In addition, a part of the base 21 forward of the tapered section 22, the tapered section 22, and the tapered cylindrical section 23 form a fitted section into which the tip of the intermediate section pipe 3 is fitted when the intermediate section pipe 3 is pulled out from the leading section pipe 2.

[0017] The leading pipe section 2 can be a steel pipe or a plastic pipe, but is preferably a steel pipe from the standpoint of strength, such as general structural carbon steel pipe STK400. The dimensions of the leading pipe section 2 can be set appropriately as needed, and for example, if the overall length of the ground reinforcement pipe 1 is approximately 3,500 mm and the thickness of the leading pipe section 2 is 4.5 mm, the outer diameter of the base section 21 can be set to 114.3 mm, the inner diameter of the base section 21 to 105.3 mm, the outer diameter of the tapered tubular section 23 to 108.0 mm, and the inner diameter of the tapered tubular section 23 to 99.0 mm, etc.

[0018] The intermediate pipe section 3 is formed in a substantially cylindrical shape and has a base section 31 formed with substantially the same outer diameter and inner diameter, a tapered section 32 whose diameter gradually increases from the front end of the base section 31 toward the front side, an expanding diameter tubular section 33 extending forward from the front end of the tapered section 32 and formed with substantially the same outer diameter and inner diameter as the tapered section 32, a tapered section 34 whose diameter gradually decreases from the rear end of the base section 31 toward the rear side, and a reducing diameter tubular section 35 extending rearward from the rear end of the tapered section 34 and formed with substantially the same outer diameter and inner diameter.

[0019] The base 31 is formed with a discharge hole 36, which is a through hole that discharges soil improvement material into the ground around the intermediate pipe section 3. In addition, the enlarged diameter cylindrical section 33, the tapered section 32, and a part of the base 31 behind the tapered section 32 form a fitting section that fits into a fitting section formed by a part of the base 21 in front of the tapered section 22 of the leading pipe section 2, the tapered section 22, and the reduced diameter cylindrical section 23, when the intermediate pipe section 3 is pulled out from the leading pipe section 2.

[0020] Furthermore, the part of the base 31 forward of the tapered portion 34, the tapered portion 34, and the reduced-diameter cylindrical portion 35 constitute a fitted portion into which the tip of the terminal section 4 is fitted when the terminal section 4 is pulled out from the intermediate section 3. When multiple intermediate section 3 with different diameters are provided by a telescopic mechanism and the rearwardly disposed intermediate section 3 is pulled out from the front intermediate section 3, a fitted portion constituted by the part of the base 31 forward of the tapered portion 34 of the front-disposed intermediate section 3, the tapered portion 34, and the reduced-diameter cylindrical portion 35 fits into a fitting portion constituted by the enlarged-diameter cylindrical portion 33 of the rearwardly disposed intermediate section 3, the tapered portion 32, and a part of the base 31 rearward of the tapered portion 32.

[0021] The intermediate pipe section 3 can be a steel pipe or a plastic pipe, but is preferably a steel pipe from the standpoint of strength, such as carbon steel pipe for mechanical structures STKM13A, etc. The dimensions of the intermediate pipe section 2 can be set appropriately as needed, and for example, if the overall length of the ground reinforcement pipe 1 is approximately 3,500 mm and the thickness of the intermediate pipe section 3 is 5.0 mm, the outer diameter of the expanded cylindrical portion 33 can be set to 101.3 mm, the inner diameter of the expanded cylindrical portion 33 can be set to 91.3 mm, the outer diameter of the base portion 31 can be set to 95.0 mm, the inner diameter of the base portion 31 can be set to 85.0 mm, the outer diameter of the reduced diameter cylindrical portion 35 can be set to 90.3 mm, and the inner diameter of the reduced diameter cylindrical portion 35 can be set to 80.3 mm, etc.

[0022] The outer diameter of the base 31 of the intermediate section tube 3 is smaller than the inner diameter of the reduced diameter tubular section 23 of the leading section tube 2 or the inner diameter of the reduced diameter tubular section 35 of the intermediate section tube 3 located further forward, and the outer diameter of the expanded diameter tubular section 33 of the intermediate section tube 3 is larger than the inner diameter of the reduced diameter tubular section 23 of the leading section tube 2 or the inner diameter of the reduced diameter tubular section 35 of the intermediate section tube 3 located further forward, so that the intermediate section tube 3 located rearward is telescopically provided relative to the leading section tube 2 or the intermediate section tube 3 located further forward, and is fitted and connected when extended.

[0023] The terminal pipe section 4 is formed in a substantially cylindrical shape and has a base section 41 formed with substantially the same outer diameter and inner diameter, a tapered section 42 whose diameter gradually increases from the front end of the base section 41 toward the front, and an expanded-diameter tubular section 43 extending forward from the front end of the tapered section 42 and formed with substantially the same outer diameter and inner diameter. The base section 41 is formed with a discharge hole 44, which is a through-hole that discharges soil improvement material into the ground surrounding the terminal pipe section 4. In addition, the expanded-diameter tubular section 43, the tapered section 42, and a portion of the base section 41 behind the tapered section 42 constitute a fitting section that fits into a fitting section composed of a portion of the base section 31 in front of the tapered section 34 of the intermediate pipe section 3, the tapered section 34, and the reduced-diameter tubular section 35 when the terminal pipe section 4 is pulled out from the intermediate pipe section 3.

[0024] The terminal pipe section 4 can be a steel pipe or a plastic pipe, but is preferably a steel pipe from the standpoint of strength, such as general structural carbon steel pipe STK400. The dimensions of the terminal pipe section 4 can be set appropriately as needed, and for example, if the overall length of the ground reinforcement pipe 1 is approximately 3,500 mm and the thickness of the terminal pipe section 4 is 4.2 mm, the outer diameter of the enlarged cylindrical portion 43 can be set to 81.0 mm, the inner diameter of the enlarged cylindrical portion 43 to 72.6 mm, the outer diameter of the base portion 41 to 76.3 mm, and the inner diameter of the base portion 41 to 67.9 mm, etc.

[0025] The outer diameter of the base 41 of the terminal section 4 is smaller than the inner diameter of the reduced diameter cylindrical section 35 of the intermediate section 3, and the outer diameter of the expanded diameter cylindrical section 43 of the terminal section 4 is larger than the inner diameter of the reduced diameter cylindrical section 35 of the intermediate section 3. The terminal section 4 is provided so as to be freely extendable relative to the intermediate section 3 located in front, and is fitted and connected when extended.

[0026] When constructing and driving the ground reinforcement pipe 1 of the first embodiment into the ground 100, as shown in FIG. 3(a), the ground reinforcement pipe 1 is placed on the guide cell 13 of the drilling equipment, and the rear end of the ground reinforcement pipe 1, in other words, the rear end of the terminal pipe 4, is fixed in a predetermined position on the guide cell 13 by gripping it with a fixing member 14, etc., so that it is in a fixed state. Furthermore, a drilling rod 11 connected to a drilling machine 15 on the guide cell 13 is inserted into the ground reinforcement pipe 1 and attached to a drill bit 12 via a casing shoe 16, and the drill bit 12 is attached to the tip of the front pipe 2 via the casing shoe 16. This results in the tip of the drilling rod 11 being attached to the drill bit 12. The drilling rod 11 used here is composed of rod components made of hollow tubes of a predetermined length and with an outer diameter smaller than the inner diameter of the terminal pipe 4, which are connected to each other by threaded couplers and extended. The individual rod components are configured so that connection and extension work can be performed using couplers, for example, when the length of the front section pipe 2 is 3,500 mm, the length of the front rod component is 4,000 mm, so that even if the length of the ground reinforcement pipe 1 changes, the rear end of the drilling bit 12 always protrudes rearward from the ground reinforcement pipe and is connected to the drilling machine 15.

[0027] Then, the driving force of the drilling machine 15 is transmitted to the drilling bit 12 via the drilling rod 11 inserted into the ground reinforcement pipe 1, and when the leading pipe 2 is pulled while the drilling bit 12 drills into the ground 100, the intermediate pipe 3 is pulled out from the leading pipe 2, and the tip of the intermediate pipe 3 fits into and connects to the rear end of the leading pipe 2 (see Figures 3(a) and (b)).

[0028] Furthermore, as the drilling bit 12 continues to drill into the ground 100, the front section pipe 2 and the connected intermediate section pipe 3 are pulled, and the terminal section pipe 4 is pulled out from the intermediate section pipe 3, and the tip portion of the terminal section pipe 4 fits into and is connected to the rear end portion of the intermediate section pipe 3 (see Figure 4(a)).

[0029] After confirming that the ground reinforcement pipe 1 has been properly cast into the ground 100 based on the length of the drilling rod 11, the drilling rod 11 is reversed to release it from the attachment to the drilling bit 12 and pulled out, and the ground improvement material S is injected from inside the ground reinforcement pipe 1 to form a consolidated area of the ground improvement material S in the ground 100 around the ground reinforcement pipe 1 and inside the ground reinforcement pipe 1 (see Figure 4(b)).

[0030] Such a ground reinforcement pipe 1 of the first embodiment can be used, for example, as a ground reinforcement pipe 1 to be cast into the ground 100 as a long forepiling work 171 in the excavation work of a tunnel T, or as a ground reinforcement pipe 1 to be cast into the ground 100 as a long head reinforcement work 172 (see FIG. 5). In FIG. 5, 181 denotes a support and 182 denotes sprayed concrete.

[0031] According to the first embodiment, by drilling and driving the ground 100 so that the drill bit 12 pulls the leading partial pipe 2, the middle partial pipe 3 of the telescopic mechanism is pulled out from the leading partial pipe 2 and automatically connected to the leading partial pipe 2, and then the terminal partial pipe 4 of the telescopic mechanism is pulled out from the middle partial pipe 3 and automatically connected to the middle partial pipe 3, and the partial pipes are automatically connected to each other to construct a long ground reinforcement pipe 1 which can be driven into the ground 100. Therefore, the long ground reinforcement pipe 1 can be driven into the ground 100 without the need to connect the partial pipes that make up part of the long ground reinforcement pipe 1 to each other with screws.

[0032] Furthermore, when constructing a ground reinforcement pipe 1 using a drilling rod 11 that connects rod components, it is possible to confirm that the intermediate and terminal pipes 3 and 4, which correspond to the subsequent pipes, are properly unwound from the leading pipe 2 based on the length of the drilling rod 11.

[0033] As a modified example, the ground reinforcement pipe 1 of the first embodiment can also be provided with multiple intermediate pipe sections 3, in which case a very long ground reinforcement pipe 1 can be driven into the ground 100. Furthermore, it becomes possible to freely set the length and number of each intermediate pipe section 3 that constitutes a long ground reinforcement pipe 1 of a specific length, thereby increasing the degree of freedom in designing and manufacturing the ground reinforcement pipe 1.

[0034] [Ground reinforcement pipe of second embodiment] As shown in Fig. 6, a ground reinforcement pipe 1a according to a second embodiment of the present invention has a ring-shaped stopper 5 fixed to the rear end of the terminal partial pipe 4, which constitutes the rearmost subsequent partial pipe, and the outer diameter of the stopper 5 is larger than the outer diameter of the base 21 of the leading partial pipe 2. A centralizer 19 for centering the ground reinforcement pipe 1a is provided on the guide cell 13 of the drilling equipment on which the ground reinforcement pipe 1a of the second embodiment is mounted, and the centralizer 19 has a support portion 191 that is substantially arc-shaped and concave and has a diameter corresponding to the outer diameter of the base 21 of the leading partial pipe 2. The support portion 191 can support the ground reinforcement pipe 1a or its leading partial pipe 2 in a placed state, but in this embodiment it is designed to support a centering ring 6, which will be described later.

[0035] The stopper 5 at the rear end of the terminal partial pipe 4 is formed larger than the outer diameter of the base 21 of the front partial pipe 2, so that when the front partial pipe 2 is pulled during drilling and pouring of the ground reinforcement pipe 1a, and the intermediate partial pipe 3 and terminal partial pipe 4 are successively pulled out and connected, the stopper 5 is hooked to the rear side of the centralizer 19, and the rearmost end of the ground reinforcement pipe 1a is fixed in a predetermined position on the guide cell 13.

[0036] Furthermore, in the ground reinforcement pipe 1a of the second embodiment, a centering ring 6 is provided in front of the stopper 5. The centering ring 6 is formed with approximately the same outer diameter as the base 21 of the leading partial pipe 2 and is placed on the support part 191 of the centralizer 19. That is, the centering ring 6 is fixed to the rearmost end of the terminal partial pipe 4, and the ring-shaped stopper 5 is fixed so as to be stacked on the centering ring 6. The centering ring 6, which has approximately the same outer diameter as the base of the leading partial pipe 2, is placed on the centralizer 19, and the ground reinforcement pipe 1a or its leading partial pipe 2 is centered when drilling and installing the ground reinforcement pipe 1a.

[0037] Other configurations of the ground reinforcement pipe 1a of the second embodiment and the construction method thereof are similar to those of the ground reinforcement pipe 1 of the first embodiment. The ground reinforcement pipe 1a of the second embodiment can also be used as the ground reinforcement pipe 1a to be driven into the ground 100 in a long forepiling work 171 during the excavation work of a tunnel T, or as the ground reinforcement pipe 1a to be driven into the ground 100 in a long head reinforcement work 172 (see FIG. 5).

[0038] According to the second embodiment, by using a configuration in which the stopper 5 is hooked onto the centralizer 19, the rear end of the terminal partial pipe 4 can be fixed using the centralizer 19 of the drilling device, and the intermediate partial pipe 3 and terminal partial pipe 4 can be smoothly pulled out and connected in accordance with the progress of drilling and the pulling of the front partial pipe 2, and the long ground reinforcement pipe 1a can be driven into the ground 100.

[0039] Furthermore, the centering ring 6 allows the centering of the front section pipe 2, the middle section pipe 3, the terminal section pipe 4 and the drilling rod 11, allowing the drilling work into the ground 100 and the installation work of the long ground reinforcement pipe 1a into the ground 100 to be carried out smoothly and reliably. In addition, the ground reinforcement pipe 1a and its installation method of the second embodiment can obtain corresponding effects from the configuration corresponding to the ground reinforcement pipe 1 and its installation method of the first embodiment.

[0040] [Scope of the invention disclosed herein] The inventions disclosed in this specification include, in addition to the individual inventions and embodiments listed as inventions, those specified by modifying partial contents of these with other contents disclosed in this specification, those specified by adding other contents disclosed in this specification to these contents, or those specified by deleting partial contents of these to the extent that partial effects can be obtained and creating a generic concept. The inventions disclosed in this specification also include the following contents and modifications.

[0041] For example, the ground reinforcement pipe 1 of the first embodiment and the ground reinforcement pipe 1a of the second embodiment are suitable for being cast into the ground 100 as long forepiling works 171 or long head reinforcement works 172 in the excavation work of a tunnel T, but they can also be cast into the ground and used as ground reinforcement pipes for any appropriate ground reinforcement method within the applicable range. Furthermore, the ground reinforcement pipe of the present invention includes, within the spirit of the present invention, those that extend and retract in two or more stages using a telescopic mechanism and are fitted and connected. [Industrial Applicability]

[0042] The present invention can be used, for example, as a ground reinforcement pipe to be installed in long fore-reinforcement works or long head reinforcement works in tunnel excavation work. [Explanation of symbols]

[0043] 1, 1a...ground reinforcement pipe 2...front section pipe 21...base 22...tapered section 23...reduced diameter cylindrical section 24...discharge hole 3...middle section pipe 31...base 32...tapered section 33...expanded diameter cylindrical section 34...tapered section 35...reduced diameter cylindrical section 36...discharge hole 4...end section pipe 41...base 42...tapered section 43...expanded diameter cylindrical section 44...discharge hole 5...stopper 6...centering ring 11...boring rod 12...boring bit 13...guide cell 14...fixing member 15...boring machine 16...casing shoe 171...long fore-end support 172...long head reinforcement 181...shoring 182...shotcrete 19...centralizer 191...support section 100...ground S...ground improvement material T...tunnel

Claims

1. A ground reinforcement pipe into which a drilling rod can be inserted, The leading pipe, to which the drill bit is attached, is inserted into the trailing pipe by a telescopic mechanism. The trailing partial tube is provided so as to be extendable relative to the leading partial tube, and is fitted together to be in a connected state when extended; a ring-shaped stopper is provided at the rear end of the terminal partial tube constituting the rearmost trailing partial tube, the stopper being hooked onto a centralizer provided on a guide cell of a drilling device; The stopper has an outer diameter larger than the outer diameter of the base of the leading end tube, A ground reinforcement pipe characterized in that a centering ring formed with approximately the same outer diameter as the base of the leading section pipe and placed on the centralizer is stacked on the front side of the stopper.

2. Another subsequent partial pipe is inserted into the subsequent partial pipe in one or more stages by a telescopic mechanism, 2. The ground reinforcing pipe according to claim 1, wherein the subsequent pipe sections are provided so as to be mutually extendable and retractable, and are connected by fitting together when extended.

3. The mating portion is composed of a part of the approximately cylindrical base of the leading section tube, a tapered portion that gradually reduces in diameter from the rear end of the base of the leading section tube toward the rear side, and a tapered cylindrical portion of the leading section tube that extends rearward from the rear end of the tapered portion of the leading section tube, a fitting portion is formed by a portion of the substantially cylindrical base portion of the trailing pipe section, a tapered portion of the trailing pipe section whose diameter gradually increases from the front end of the base portion of the trailing pipe section toward the front side, and an expanded diameter cylindrical portion of the trailing pipe section that extends forward from the front end of the tapered portion of the trailing pipe section, 3. The ground reinforcement pipe according to claim 1, wherein the fitting portion and the fitted portion are fitted together to connect the trailing pipe section to the leading pipe section when the pipe is extended.

4. A method for constructing the ground reinforcement pipe according to any one of claims 1 to 3, A method for constructing a ground reinforcement pipe, characterized by comprising the steps of: placing the rearmost end of the ground reinforcement pipe at a predetermined position on the guide cell of a drilling device; connecting the tip of a drilling rod inserted into the ground reinforcement pipe to a drilling bit attached to the front partial pipe to transmit the driving force of the drilling machine; drilling with the drilling bit while pulling the front partial pipe to pull out the trailing partial pipe; and fitting and connecting the trailing partial pipe to the front partial pipe.

Images