Casing packer

Abstract

To provide a casing packer that can maintain water stopping properties and move more smoothly forward and backward within a casing while solving problems caused in pull-out work of the casing used in casing drilling including anchor casing in a conventional manner.SOLUTION: A check valve device (2) is provided at a ground surface end part of a main shaft (1) which serves as an injection path for a grout material, a cylindrical stabilizing part (3) with a chamfered bottom outer edge is provided on an outer circumferential surface of an underground end part of the main shaft, and multiple truncated cone-shaped elastic bushes (4) with a flange on the bottom outer edge are attached to an outer circumferential surface of the main shaft between the check valve device and the stabilizing part. A cylindrical rigid bush (5) is attached between the elastic bushes.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a casing packer used in drilling casing holes for anchor installation on the side walls of a cut section.

[0002] When burying long objects such as ground anchors and measuring pipes in the ground, when drilling casing holes, the casing material used for drilling is pulled out of the ground. For example, in anchor construction, the anchor casing driven into the ground to form an anchor hole needs to be pulled out of the ground during the process of injecting grout material to fix the tendon tension member in the ground. However, when groundwater is present in the ground, various problems occur during the anchor casing pulling work, such as overflow of grout material due to the inflow of pressurized water into the anchor casing, and the tendency of the tendon tension member and the anchor casing to rise up due to the inflow of soil and sand when the pressurized water flows in. Therefore, various attempts have been made to solve the problems that occur during the anchor casing pulling work.

[0003] The applicants have proposed a packer for anchor casing, disclosed in Japanese Patent No. 3948669, as a means for solving problems that arise during the operation of extracting anchor casings. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3948669 DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0005] The above-mentioned conventional anchor casing packer is configured such that a check valve device is provided at the surface side end of the main shaft which serves as the injection path for the grout material, a cylindrical stabilizing part with a chamfered bottom outer edge is provided on the outer circumferential surface of the underground side end of the main shaft, and a cylindrical elastic bush with a flange (lip) is attached to the outer circumferential surface of the main shaft between the check valve device and the stabilizing part. The check valve device prevents the grout material from overflowing, and the lip of the elastic bush prevents the pressurized water from overflowing.

[0006] In addition, because it is equipped with a stabilizing section, when removing the component located closest to the ground surface of an anchor casing made up of multiple connected components, it can be smoothly pushed in to the position of the underground component connected to the component to be removed. This makes it possible to efficiently remove the anchor casing using a boring machine.

[0007] However, in the above-mentioned conventional packers for anchor casings, an inclination occurs with respect to the axis of the anchor casing, and this inclination can cause a decrease in watertightness and can also hinder advancement and retreat operations within the anchor casing.

[0008] Therefore, the present invention aims to provide a casing packer that solves the problems that arise in the pulling out operation of casings used in casing drilling, including anchor casings, as in the conventional case, while maintaining watertightness and being able to move forward and backward more smoothly within the casing. [Means for solving the problem]

[0009] The casing packer according to the present invention is provided with a check valve device at the surface end of the main shaft which serves as an injection path for grout material, a cylindrical stabilizing section with a chamfered bottom outer edge is provided on the outer circumferential surface of the underground end of the main shaft, and a plurality of truncated cone-shaped elastic bushings having a flange at the bottom outer edge are attached to the outer circumferential surface of the main shaft between the check valve device and the stabilizing section, and cylindrical rigid bushings are attached between the elastic bushings.

[0010] The elastic bushing has a density of 0.3 to 0.7 g / cm 3 The flange may be formed from a synthetic resin material, and may be 79 mm or more and 110 mm or less when the casing nominal diameter is 90 mm, 115 mm or more and 155 mm or less when the casing nominal diameter is 135 mm, and 147 mm or more and 185 mm or less when the anchor casing nominal diameter is 165 mm. Effect of the Invention

[0011] The casing packer of the present invention solves the problems that arise during the casing extraction work in the same way as in the conventional case, while maintaining watertightness and allowing the packer to move forward and backward more smoothly within the casing.

[0012] The elastic bushing is made of a material with a density of 0.3 to 0.7 g / cm 3 By forming the flange from a synthetic resin material and making the flange 79 mm or more and 110 mm or less when the casing nominal diameter is 90 mm, 115 mm or more and 155 mm or less when the casing nominal diameter is 135 mm, and 147 mm or more and 185 mm or less when the casing nominal diameter is 165 mm, it can be made to move forward and backward even more smoothly within the casing. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a vertical cross-sectional view showing an embodiment of a casing packer according to the present invention. [Diagram 2]1A and 1B are schematic diagrams showing changes in state when a conventional anchor casing packer is pushed into an anchor casing, in which (a) is a diagram showing the state when the pushing starts, (b) is a diagram showing the state when the packer starts to tilt immediately after the pushing starts, and (c) is a diagram showing the state when the packer is being pushed in. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] With reference to FIG. 1, an embodiment of a packer for a casing according to the present invention will be described. The casing packer according to this embodiment is intended to be used for anchor construction, and is provided with a check valve device 2 at the surface end 1a of the main shaft 1, which serves as the injection path for grout material, and a cylindrical stabilizing section 3 with a chamfered bottom outer edge is provided on the outer periphery near the underground end 1b of the main shaft 1. Two truncated conical elastic bushes 4 having a flange 41 on the bottom outer edge are attached to the outer periphery of the main shaft 1 between the check valve device 2 and the stabilizing section 3. A cylindrical rigid bush 5 is attached between the elastic bushes 4.

[0015] The main shaft 1 is made of a metal pipe material, and its outer diameter is set according to the nominal diameter (drilled hole diameter) of the anchor casing. Specifically, it is set to 32 mm when the nominal diameter of the anchor casing is 90 mm, and 58 mm when the nominal diameter of the anchor casing is 135 mm or 165 mm.

[0016] In addition, a thread is engraved on the inner peripheral surface of the surface side end 1a of the main shaft 1 for attaching a check valve device 2. Furthermore, a thread is engraved on the outer peripheral surface of the underground side end 1b of the main shaft 1 for attaching a cylindrical member forming a stabilizing portion 3.

[0017] The check valve device 2 is composed of a holder 22 that houses a valve body 21, and a socket 23 having a male thread portion for mounting to the ground surface side end 1a of the main shaft 1.

[0018] In the holder 22, the internal space that houses the valve body 21 opens at the surface side end face and the underground side end face of the holder 22, and the inner circumference forms an inclined surface that expands in diameter from the surface side to the underground side. The end of the socket 23 opposite the male thread portion is inserted into the opening at the underground side end face of the holder 22. A return spring 24 is disposed between the end face of the socket 23 and the valve body 21, and the valve body 21 biased by the return spring 24 closes the opening at the surface side end face of the holder 22, thereby preventing the backflow of grout material.

[0019] The socket 23 has a through hole that penetrates the male thread and opens at the end face inserted into the opening of the holder 22. The injected grout material pushes the valve body 21 back into the ground against the biasing force of the return spring 24, passes through the open opening of the holder 22, passes through the internal space of the holder 22, and flows into the main shaft 1 through the through hole of the socket 23.

[0020] The cylindrical member forming the stabilizing portion 3 has a thread engraved on its inner circumferential surface, which is adapted to screw into a thread engraved on the outer circumferential surface of the underground end 1b of the main shaft 1.

[0021] In addition, the outer edge 31 of the bottom surface of the cylindrical member that forms the stabilizing portion 3, which is located underground, is chamfered. When removing the member located closest to the ground surface of the anchor casing, which is made up of multiple members connected together, the anchor casing is unlikely to encounter resistance from the grout material filled inside the anchor casing when it is pushed in to the position of the underground member connected to the member to be removed.

[0022] Furthermore, a groove 32 for fitting a fastening tool such as a U-shaped wrench is provided on the outer periphery of the side surface of the cylindrical member forming the stabilizing portion 3. The elastic bushing 4 and the rigid bushing 5 attached to the main shaft 1 can be fastened, and the stabilizing portion 3, the elastic bushing 4, and the rigid bushing 5 can be removed from the main shaft 1.

[0023] Furthermore, an annular recess is provided on the edge of the opening of the through hole in the bottom surface of the cylindrical member forming the stabilizing portion 3, which is located on the ground surface side, and the protruding end of the elastic bushing 4 is fitted into this recess, thereby preventing the elastic bushing 4 from slipping.

[0024] In this embodiment, steel is used as the material for the cylindrical member that forms the stabilizing portion 3. However, other known rust-resistant materials such as stainless steel may be used for the stabilizing portion 3 as long as the stabilizing portion 3 has sufficient rigidity not to be deformed by the pressure applied from the front during the above-mentioned pushing operation.

[0025] The elastic bush 4 is designed so that the flange 41 provided on the outer edge of the bottom surface placed on the ground surface side can maintain the required contact state with the inner surface of the anchor casing. In other words, the flange 41 is in close contact with the inner surface of the anchor casing to prevent leakage of the grout material and pressurized water inside the anchor casing, and is in close contact with the inner surface of the anchor casing to an extent that does not interfere with movement inside the anchor casing.

[0026] In order to bring the flange 41 into contact with the inner surface of the anchor casing, the elastic bush 4 is made of a material having a density of 0.3 to 0.7 g / cm 3 It is preferable that the flange 41 is made of a synthetic resin material such as 79 mm or more and 110 mm or less when the nominal diameter of the anchor casing is 90 mm, 115 mm or more and 155 mm or less when the nominal diameter of the anchor casing is 135 mm, and 147 mm or more and 185 mm or less when the nominal diameter of the anchor casing is 165 mm.

[0027] In this embodiment, the number of elastic bushes 4 is two, but there is no limit to the number, and an appropriate number may be provided depending on the work environment and conditions.

[0028] The rigid bushing 5 has a rigidity that does not deform due to pressure received from the front during the above-mentioned pushing operation, thereby maintaining the distance between the elastic bushings 4. In this embodiment, the rigid bushing 5 is made of the same steel material as the cylindrical member that forms the stabilizing portion 3. However, other known materials that are resistant to rust, such as stainless steel, may be used as long as they have the required rigidity.

[0029] In addition, a ring-shaped recess is provided on the edge of the opening of the through hole in the bottom surface of the rigid bushing 5 that is placed on the ground surface side, and the protruding end of the elastic bushing 4 is fitted into this recess, thereby preventing the elastic bushing 4 from slipping.

[0030] Furthermore, a movement prevention ring 6 is interposed between the bottom surface of the rigid bushing 5 that is disposed underground and the elastic bushing 4 that is disposed underground relative to the rigid bushing 5. Thus, a gap is maintained between the two elastic bushings 4.

[0031] In the conventional anchor casing packer, when the push rod is used to push the packer to a predetermined position during the anchor casing extraction operation, a slight inclination (tilt) may occur as shown in Figures 2(b) and (c). Therefore, in the conventional anchor casing packer, the axis of the packer may not coincide with the axis of the anchor casing. Furthermore, in many cases, a small step is formed at the connection part of the anchor casing (the joint part between the male and female threads) due to a slight dimensional error in the inner diameter part of the casing during the casing manufacturing process, and this step is also a factor that increases the inclination when the anchor casing packer is inserted. However, in the anchor casing packer according to this embodiment, when the packer is pushed to a predetermined position in the anchor casing, it does not incline with respect to the axis of the anchor casing, and it does not incline when moving over the step formed in the anchor casing.

[0032] It should be noted that the embodiment shown in FIG. 1 is intended to be used for anchor installation, but the casing packer of the present invention is not limited to this and can also be used for construction work involving casing drilling other than anchor installation, such as burying an instrument pipe. EXAMPLES

[0033] In ground anchor construction aimed at providing earth retaining support during excavation work, a casing extraction operation was carried out using the casing packer of the embodiment shown in Figure 1. The ground anchor installation specifications in the example were a drilled hole length of approximately 20 m per anchor, and an anchor installation angle of θ = 30 degrees downward from the horizontal plane. The dimensions of the casing used (nominal diameter φ135mm) were an outer diameter of 133mm and an inner diameter of φ114mm. The casings used were 1.0 m long each, and 20 of these were connected together by screwing them together, after which a hole of approximately 20 m was drilled and the casings were installed underground.

[0034] After the drilling was completed, the injection hose was inserted from the casing end on the ground side to the bottom of the casing hole, and the grout material mixed in the injection plant was injected. After the injection inside the casing was completed, the injection hose was pulled out from the casing, and the tendon tensioning material prepared in advance was inserted into the casing from the casing end on the ground side. After confirming that the tendon tensioning material was inserted in the designated position, the casing packer was inserted into the casing. The casing packer used in the examples has an elastic bush made of urethane foam, the density of which is 0.5 g / cm 3 The outer diameter of the tsuba is 122 mm.

[0035] Once the casing packer was inserted, the grout was pumped through the swivel of the drilling machine connected to the end of the casing above ground, and the grout was infiltrated into the soil from the tip of the casing on the underground side. During this process, the grout passes through the main shaft of the casing packer and reaches the tip of the casing on the underground side. Note that the inflow of groundwater into the casing due to water pressure from the soil is prevented by the check valve device equipped on the casing packer.

[0036] After the infiltration of the grout material was completed, the casing extraction work began. First, the length of one casing (1.0 m) was pulled out toward the ground, the swivel was detached from the casing, and a special pushing rod was attached to the casing packer that was pulled up together with the casing, and it was pushed into the ground using the driving force of the drilling machine's drifter. During this process, the casing packer was pushed in the length (1.0 m) equivalent to one casing, and inserted into the casing that was to be detached in the next process. By repeating this process, all of the casings that had been installed underground were retrieved.

[0037] Even in the above embodiment, the casing packer did not tilt relative to the axis of the casing, and even when it moved over the step formed in the casing connection part, no leakage of grout material occurred, watertightness was maintained, and it was possible to move smoothly back and forth within the casing. [Explanation of symbols]

[0038] 1 Main shaft 1a Ground side edge 1b Underground end 2. Check valve device 3 Stable part 4 Elastic bushing 5 Rigid bushing 6 Anti-movement ring 7 Head Cap 21 Valve body 22 Holder 23 Socket 24 Return spring 31 Outer edge of base 32 Groove 41 Tsuba

Claims

1. A check valve device is provided at the ground surface end of the main shaft, which serves as the grout injection path; A cylindrical stabilizing portion having a chamfered bottom outer edge is provided on the outer peripheral surface of the underground end of the main shaft, A plurality of truncated cone-shaped elastic bushes having a flange on the bottom outer edge are attached to the outer peripheral surface of the main shaft at a portion between the check valve device and the stabilizing portion, A packer for a casing, characterized in that a cylindrical rigid bush is mounted between the elastic bushes.

2. The elastic bushing has a density of 0.3 to 0.7 g / cm ３ The casing packer according to claim 1, which is formed of a synthetic resin material, and the flange is 79 mm or more and 110 mm or less when the casing nominal diameter is 90 mm, 115 mm or more and 155 mm or less when the casing nominal diameter is 135 mm, and 147 mm or more and 185 mm or less when the casing nominal diameter is 165 mm.

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