JP5504063B2 - Tubular anchor device and tubular body retaining method - Google Patents

Description

  The present invention relates to a tubular body anchor device and a tubular body retaining method, and more specifically, when pulling out a casing rod from the ground, the tubular body inserted into the casing rod is more reliably pulled out together with the casing rod. The present invention relates to a tubular anchor device and a tubular body retaining method that can be prevented.

  In order to strengthen the soft ground, a construction method is known in which a ground improvement chemical is injected into the ground using a double pipe composed of an outer pipe and an inner pipe. In this ground improvement method, after drilling the ground with a casing rod, the outer tube is inserted into the casing rod installed in the drilling hole, and then the casing rod is pulled out on the ground, leaving the outer tube in the ground. Set to a fixed state. Next, the inner pipe is inserted into the outer pipe, the ground improving chemical solution is supplied through the inner pipe, and the ground improving chemical liquid is infiltrated and injected into the ground from the discharge port provided in the outer pipe. An anchor is provided at the tip of the outer tube so that the outer tube is not pulled out together with the casing rod when the casing rod is pulled out.

  Various types of this anchor have been proposed (see, for example, Patent Documents 1 and 2). Patent Document 1 discloses an anchor formed by spring blades (blade members) spreading on the outer peripheral side of the outer tube. In Patent Document 2, an anchor having a wing member that can be folded (see FIG. 1A), an anchor using a weight (see FIG. 1B), and an anchor using a bag body that inflates by injecting fluid (FIG. 1). -C) is illustrated. In order to increase the pulling resistance, an anchor having a blade member spreading on the outer peripheral side of the outer tube and an anchor using an expanding bag body are excellent. However, in the structure in which the blade member is expanded using the biasing force of the spring, it is difficult to appropriately set the biasing force of the spring according to the hardness of the ground. If the biasing force of the spring is too small compared to the hardness of the ground, the blade member does not spread sufficiently, so that a sufficient retaining effect cannot be obtained. On the other hand, when the biasing force of the spring is excessive, there arises a problem that it becomes difficult to smoothly insert the outer tube into the casing.

  With an anchor using a bag that expands due to the injected fluid, it is impossible to grasp how much the bag has actually expanded in the ground. Therefore, even if a high water pressure is applied to inject the fluid into the bag body, a sufficient retaining effect may not be obtained.

JP-A-1-131715 JP-A-2005-42426

  An object of the present invention is to provide a tubular anchor device and a tubular body retaining method that can more reliably prevent a tubular body inserted into a casing rod from being pulled out together with the casing rod when the casing rod is pulled out of the ground. There is to do.

  In order to achieve the above object, a tubular anchor device according to the present invention is a tubular anchor device that fixes a tubular body inserted into a casing rod provided in a drilling hole in a ground. A cylinder that is attached to the cylinder, a water injection pipe that is detachably connected to the rear end of the cylinder, water pressure applying means for supplying water into the cylinder through the water injection pipe, A piston that moves to the side, a pressing member that moves together with the piston toward the front end of the cylinder, an opening and closing blade that is pressed by the pressing member and extends in the cylinder outer circumferential direction, and a water pressure sensor that detects the water pressure in the cylinder, An outflow portion for allowing water in the cylinder to flow out of the cylinder is provided at a predetermined position of the cylinder, and the piston is provided at a position where the outflow portion is provided. By moving, characterized by being configured the closing blade so as to increase at a predetermined opening angle to the cylinder outer peripheral direction.

  Here, a holding plate for holding the opening / closing blade vertically is provided, the opening / closing blade is pivotally supported on the holding plate, a guide hole extending in the cylinder axial direction is provided on the holding plate, and A guide protrusion may be provided on the pressing member, and the guide protrusion may be moved along the guide hole when the pressing member moves. In this configuration, the opening and closing blades are covered with the cover body together with the holding plate, and the cover body can be cut by the opening and closing blades when the opening and closing blades spread in the cylinder outer peripheral direction. In the present invention, the opening / closing blade may be provided with a protruding portion protruding from the surface thereof.

  The tubular body retaining method according to the present invention is a tubular body retaining method in which a tubular body inserted into a casing rod provided in a drilling hole is fixed in the ground, and a cylinder is attached to the tip of the tubular body. A piston that moves in the cylinder toward the tip of the cylinder, a pressing member that moves together with the piston toward the tip of the cylinder, and an opening and closing blade that is pressed by the pressing member and spreads in the cylinder outer peripheral direction. After being inserted into the casing rod, water is supplied into the cylinder through a water injection pipe detachably connected to the rear end of the cylinder, and the pressing member is moved together with the piston by the water pressure of the supplied water. , In the ground at the tip of the casing rod, the opening and closing blades are spread in the cylinder outer peripheral direction, and the piston is a predetermined cylinder When moving to the outflow portion provided at the position, the water in the cylinder is caused to flow out of the cylinder from the outflow portion, and after the water pressure drop in the cylinder due to the outflow of water is detected by the water pressure sensor, The casing rod is pulled out on the ground.

  According to the anchor device of the present invention, a cylinder attached to the distal end portion of the tubular body, a water injection pipe detachably connected to the rear end of the cylinder, and water pressure applying means for supplying water into the cylinder through the water injection pipe And a piston that moves to the front end side of the cylinder by the water pressure of the supplied water, a pressing member that moves to the front end side of the cylinder together with the piston, and an opening and closing blade that is pressed by the pressing member and spreads in the cylinder outer peripheral direction. And, because the opening and closing blades are spread at a predetermined opening angle in the cylinder outer peripheral direction before the piston moves to the outflow portion provided at a predetermined position of the cylinder, according to the hardness of the ground, The opening and closing blades can be expanded by changing the water pressure of the supplied water. For this reason, when the pipe body equipped with this anchor device is inserted into the casing rod provided in the drilling hole and then water is supplied into the cylinder through the water injection pipe, the opening and closing is performed in the ground at the tip of the casing rod. The blades can be smoothly spread in the cylinder outer peripheral direction.

  When the piston moves to the outflow portion, the water in the cylinder flows out of the cylinder through the outflow portion, and the water pressure in the cylinder decreases. Since the present invention includes a water pressure sensor that detects the water pressure in the cylinder, the water pressure sensor can detect a decrease in the water pressure. That is, it can be grasped by the water pressure sensor that the piston has moved to the outflow portion and the opening / closing blade has spread at a predetermined opening angle in the ground. Therefore, if the casing rod is pulled out on the ground after detecting a decrease in the water pressure in the cylinder, the tube body can be more reliably prevented from being pulled out together with the casing rod. can do.

  By using the anchor device of the present invention described above, the tubular body retaining method of the present invention can be implemented. Therefore, when pulling out the casing rod from the ground, it is possible to more reliably prevent the tubular body inserted into the casing lot from being pulled out together with the casing rod.

It is a top view which illustrates the internal structure of the cylinder peripheral part of the anchor apparatus of this invention. It is a front view which illustrates the internal structure of the opening-and-closing blade periphery part of FIG. It is a top view which illustrates the state in the middle of the open / close blade of FIG. 1 being opened. It is a top view which illustrates the state where the opening-and-closing blade of FIG. 1 opened completely. It is a partially expanded sectional view of a cylinder. FIG. 6 is a cross-sectional view illustrating a state in which water flows out from the inside of the cylinder in FIG. 5. It is explanatory drawing which illustrates the whole outline | summary of the anchor apparatus of this invention. It is explanatory drawing which illustrates the state which expanded the opening-and-closing blade in the ground. FIG. 9A is a plan view showing a modified example of the opening and closing blades, and FIG. 9B is a view as seen in the direction of arrow B in FIG. 9A. It is a top view which illustrates the internal structure of the cylinder peripheral part of another embodiment of an anchor apparatus. It is a front view which illustrates the internal structure of the opening-and-closing blade periphery part of FIG. It is explanatory drawing which illustrates the internal structure of a connection part. It is explanatory drawing which illustrates the state which separated the water injection pipe from the rear end of the cylinder.

  Hereinafter, the tubular anchor device and tubular body retaining method of the present invention are based on an embodiment in which a ground improvement chemical solution is injected into the ground using a double tube composed of an outer tube and an inner tube. I will explain.

  As illustrated in FIGS. 1, 2, and 7, the anchor device 1 of the present invention is detachably connected to a cylinder 6 attached to the distal end portion of the outer tube 15 and a rear end of the cylinder 6 via a connecting portion 10. A water injection pipe 12a and water pressure applying means 13 for supplying water W into the cylinder 6 through the water injection pipe 12a are provided. The outer tube 15 becomes a tube body to be fixed in the ground according to the present invention. The water pressure application means 13 is a water pump or the like installed on the ground, and a water injection pipe 12 a is connected to a water injection hose 12 b connected to the water pressure application means 13.

  The water injection hose 12b is provided with a water pressure sensor 14 for detecting the water pressure in the cylinder 6. The water pressure sensor 14 can also be provided in the water pressure applying means 13 or the water injection pipe 12a.

  The cylinder 6 is a cylindrical body having an open front end, and inside thereof, a piston 7 that moves to the front end side of the cylinder 6 by the water pressure of the supplied water W, and a pressing member that protrudes and moves from the front end opening of the cylinder 6. 3 is provided. The pressing member 3 has a rear end in contact with the piston 7 and moves together with the piston 7 toward the front end side of the cylinder 6. The pressing member 3 is a flat plate made of metal or the like formed in an arrow shape. A guide protrusion 3 a is provided on the front surface of the pressing member 3. The piston 7 and the pressing member 3 can be integrated.

  A pair of holding plates 4 that sandwich the pressing member 3 vertically are fixed to the tip of the cylinder 6. Two holding blades 2 are pivotally supported on the holding plate 4 by a support shaft 5. The open / close blades 2 are arranged so as to overlap each other so that the axial center line of the cylinder 6 is symmetrical.

  The number of open / close blades 2 is not limited to two, but may be one or three or more, but two are preferable from the viewpoint of simplification of the structure and balance. In addition, when the two open / close blades 2 are closed, the open / close blades 2 having a larger area can be adopted in a narrow space by being stacked one above the other.

  The opening / closing blade 2 is covered with a cover body 9 together with the holding plate 4. 1-4, the cover body 9 is shown with the dashed-two dotted line. The cover body 9 is a bag body formed of a thin resin film or the like, and has an open end fixed to the outer peripheral surface of the cylinder 6 and closed.

  One holding plate 4 is provided with a guide hole 4 a extending in the axial direction of the cylinder 6. The guide projection 3a of the pressing member 3 is inserted into the guide hole 4a. When water W is supplied from the water pressure applying means 13 into the cylinder 6 through the injection hose 12 and the water injection pipe 12a, the pressing member 3 moves to the tip side of the cylinder 6 together with the piston 7 by the water pressure of the supplied water W. When the pressing member 3 moves, the guide protrusion 3a moves along the guide hole 4a.

  The pressing member 3 that moves to the distal end side of the cylinder 6 advances so as to separate the pair of opening / closing blades 2. When the opening / closing blade 2 is pressed by the pressing member 3, as illustrated in FIG. 3, it rotates about the respective support shafts 5 and spreads in the outer peripheral direction of the cylinder 6. At this time, the cover body 9 is configured to be cut by the opening / closing blades 2 spreading in the outer peripheral direction of the cylinder 6. In order to make it easy to cut the cover body 9, the opening / closing blade 2 may be provided with a sharp portion.

  When water W is further supplied into the cylinder 6, the respective opening / closing blades 2 are completely opened as illustrated in FIG. 4. In this state, the opening / closing blade 2 is configured to spread at a predetermined opening angle A in the outer circumferential direction of the cylinder 6. The predetermined opening angle A is, for example, 30 ° to 90 °.

  In this embodiment, the respective support shafts 5 are offset in the width direction of the cylinder 6 with respect to the guide holes 4a for guiding the guide protrusions 3a of the pressing member 3. Therefore, the opening / closing blade 2 can be expanded larger than the tip angle of the pressing member 3.

  As illustrated in FIG. 5, the piston 7 has a columnar shape, and a concave groove 7 a is formed in the middle in the longitudinal direction. A seal member 8 such as an O-ring is attached to the concave groove 7a. When the seal member 8 comes into contact with the inner peripheral surface of the cylinder 6, the inside of the cylinder 6 on the rear side of the seal member 8 is in a watertight state.

  A diameter-enlarged portion 6 a that has a larger inner diameter than other portions and that does not contact the seal member 8 is provided at the tip of the cylinder 6. Accordingly, when the piston 7 moves to the enlarged diameter portion 6a as illustrated in FIG. 6, the water W in the cylinder 6 flows out of the cylinder 6 from the gap between the seal member 8 and the enlarged diameter portion 6a.

  In this manner, the cylinder 6 is provided at a predetermined position with the enlarged diameter portion 6 a serving as an outflow portion for allowing the water W in the cylinder 6 to flow out of the cylinder 6. The outflow portion is not limited to the enlarged diameter portion 6a as in this embodiment, but a through hole is provided in the peripheral wall of the cylinder 6 at a predetermined position of the cylinder 6, and this through hole can be used as the outflow portion.

  Therefore, the opening / closing blade 2 is configured to spread at a predetermined opening angle A in the outer circumferential direction of the cylinder 6 until the piston 7 moves to the position where the enlarged portion 6a is provided. The water pressure in the cylinder 6 decreases due to the outflow of the water W, and the decrease in the water pressure is detected by the water pressure sensor 14.

  The retaining method of the present invention for fixing the outer tube 15 equipped with the anchor device 1 in the ground is as follows.

  First, the ground is drilled by the casing rod 16, and the casing rod 16 is provided in the formed drilling hole H. As illustrated in FIG. 7, the outer tube 15 having the anchor device 1 is inserted into the casing rod 16. At this time, the opening / closing blade 2 is closed and does not spread outward from the outer peripheral surface of the cylinder 6. Therefore, the outer tube 15 can be smoothly inserted into the casing rod 16.

  The casing rod 16 is moved slightly upward in the hole H. Then, a portion corresponding to the opening / closing blade 2 is projected from the tip of the casing rod 16, and this portion is disposed in the hole H at the tip of the casing rod 16.

  Thereafter, water W is supplied into the cylinder 6 from the water pressure applying means 13 through the water injection pipe 12a, and the opening / closing blade 2 is spread in the outer periphery of the cylinder 6 in the ground at the tip of the casing rod 16 as illustrated in FIG. Depending on the hardness of the ground, the opening and closing blades 2 can be expanded by changing the water pressure of the water W to be supplied. Therefore, the opening and closing blades 2 can be expanded smoothly in the outer peripheral direction of the cylinder 6 regardless of the hardness of the ground. it can.

  Here, the water pressure sensor 14 can detect a decrease in the water pressure in the cylinder 6 due to the water W flowing out from the enlarged diameter portion 6a. That is, it can be grasped by the water pressure sensor 14 that the piston 7 has moved to the enlarged diameter portion 6a and the opening / closing blade 2 has spread at a predetermined opening angle A in the ground.

  After the decrease in the water pressure in the cylinder 6 is detected by the water pressure sensor 14, the casing rod 16 is pulled out on the ground. At this time, the outer tube 15 is firmly held in the ground by the opening and closing blades 2 spreading at a predetermined opening angle A in the ground. Therefore, when pulling out the casing rod 16, even if a force for pulling out the outer tube 15 acts, a large resistance force is generated by the opening / closing blade 2 that spreads at a predetermined opening angle A. Thereby, it is possible to more reliably prevent the outer tube 15 from being pulled out together with the casing rod 16 and fix the outer tube 15 in the ground.

  Next, the water injection pipe 12a is removed from the rear end of the cylinder 6 and pulled up on the ground. The water injection pipe 12a can be reused without remaining in the ground.

  Thereafter, the inner tube is inserted into the outer tube 15 fixed on the ground. Next, the ground improvement chemical solution is supplied through the inner pipe, and the ground improvement chemical solution is infiltrated and injected into the ground from the discharge port provided in the outer pipe 15.

  Moreover, when the cover body 9 is provided as in the embodiment, it is possible to prevent earth and sand from entering between the holding plate 4 and the opening / closing blade 2 inserted into the ground. Therefore, it is advantageous to smoothly spread the opening / closing blade 2 in the ground.

  Further, when the guide hole 4a and the guide protrusion 3a are provided, the guide protrusion 3a moves along the guide hole 4a when the pressing member 3 moves to the tip end side of the cylinder 6, so that the pressing member 3 can be moved even in the ground. The cylinder 6 can be moved stably to the tip side. This also is advantageous for smoothly spreading the open / close blade 2 in the ground. Further, by forming the guide hole 4a at an intermediate position between the two opening / closing blades 2 (support shafts 5), the respective opening / closing blades 2 can be spread evenly.

  As illustrated in FIG. 9, the surface of the opening / closing blade 2 may be provided with a protruding portion 2 a protruding from the surface. As for the protrusion part 2a, when the opening-and-closing blade 2 spreads, it is desirable to make resistance with a ground small. On the other hand, in order to make it difficult for the outer tube 15 to be pulled out, it is desirable to increase the resistance between the protrusion 2a and the ground. Therefore, as illustrated in FIG. 9, it is preferable that the protruding portion 2 a has a shape that is inclined from the front edge side to the rear edge side of the opening / closing blade 2.

  10 and 11 illustrate another embodiment of the anchor device 1. In this embodiment, each open / close blade 2 is not directly pressed by the pressing member 3 but is pressed through the auxiliary arm 2b. Each opening / closing blade 2 has an L-shaped cross section.

  A pair of holding plates 4 that sandwich the pressing member 3 vertically are fixed to the tip of the cylinder 6. Two holding blades 2 are pivotally supported on the holding plate 4 by a support shaft 5. One end of the auxiliary arm 2b is pivotally supported by a support shaft 2c in the middle of each opening / closing blade 2 in the longitudinal direction. The other end of each auxiliary arm 2b is pivotally supported by one guide support shaft 2d. The guide support shaft 2 d is inserted into a guide hole 4 a provided in the holding plate 4.

  When water W is supplied from the water pressure applying means 13 into the cylinder 6 through the injection hose 12 and the water injection pipe 12a, the pressing member 3 moves to the tip side of the cylinder 6 together with the piston 7 by the water pressure of the supplied water W. When the pressing member 3 moves, the guide protrusion 3a moves along the guide hole 4a.

  The pressing member 3 that moves to the distal end side of the cylinder 6 advances so as to separate the pair of auxiliary arms 2b. When the auxiliary arm 2b is pressed by the pressing member 3, the guide support shaft 2d moves along the guide hole 4a and the auxiliary arm 2b rotates around the guide support shaft 2d as illustrated in FIG. And spread outward. By the movement of the auxiliary arm 2b, each opening / closing blade 2 is pressed through the support shaft 2c and rotated around the support shaft 5 to spread in the outer peripheral direction of the cylinder 6.

  In this manner, as in the previous embodiment, the opening / closing blade 2 is configured to expand at the predetermined opening angle A in the outer circumferential direction of the cylinder 6 until the piston 7 moves to the position where the enlarged diameter portion 6a is provided. ing. Also in this embodiment, it is preferable that the opening / closing blade 2 is covered with the cover plate 9 together with the holding plate 4 as in the previous embodiment.

  The rear end of the cylinder 6 and the water injection pipe 12a are connected as illustrated in FIG. This connection part 10 has the cylindrical casing 10a and the insertion body 11a inserted in the inside of the casing 10a.

  The casing 10 a is connected to the rear end portion of the cylinder 6. The casing 10a has a large-diameter cavity portion 10b on the cylinder 6 side, and a small-diameter cavity portion 10c having a smaller inner diameter on the water injection pipe 12a side following the large-diameter cavity portion 10b. Therefore, the boundary between the large-diameter cavity portion 10b and the small-diameter cavity portion 10c is a step. On the inner peripheral surface of the large-diameter hollow portion 10b, a common rotation prevention projection 10d extending in the axial direction of the casing 10a is provided.

  A water injection pipe 12a is attached to the rear end of the insert 11a. The distal end side of the insertion body 11a is a separable separating portion 11b that is attached by screwing. In the separation part 11b, a spring 11e and a pressing ball 11d urged toward the tip by the spring 11e are provided.

  In addition, a pair of stoppers 11c is pivotally supported by a support shaft 11g on the tip side of the pressing ball 11d. By being pressed by the biased pressing ball 11d, the two stoppers 11c rotate around the support shaft 11g and come into pressure contact with the inner peripheral surface of the large-diameter cavity portion 10b.

  At the center of the insert 11a, a flow path 11f penetrating in the longitudinal direction is formed. The water injection pipe 12a communicates with the inside of the cylinder 6 through the flow path 11f. A seal member such as an O-ring is appropriately provided on the outer peripheral surface of the insert 11a.

  When connecting the water injection pipe 12 a to the rear end of the cylinder 6, the insert 11 a attached to the front end of the water injection pipe 12 a is inserted into the casing 10 a fixed to the rear end of the cylinder 6. At this time, the respective stoppers 11c are pressed against the inner peripheral surface of the small-diameter cavity portion 10c to move against each other in a closing direction around the support shaft 11g against the urging force of the spring 11e. When the insertion body 11a is further advanced while the stopper 11c is in sliding contact with the small-diameter cavity portion 10c and the stopper 11c is inserted into the large-diameter cavity portion 10b, each stopper 11c is centered on the support shaft 11g by the biasing force of the spring 11e. Then, they move in the direction of opening each other and are pressed against the inner peripheral surface of the large-diameter cavity 10b. Since the stopper 11c is thus opened, even if the water injection pipe 12a is pulled out on the ground, the stopper 11c is caught by the step between the large-diameter cavity portion 10b and the small-diameter cavity portion 10c, and the water injection pipe 12a is It is connected to the cylinder 6 so as not to come off. Water supplied from the water injection pipe 12a is supplied into the cylinder 6 through the flow path 11f.

  When the water injection pipe 12a is removed from the rear end of the cylinder 6 and pulled up on the ground, the insertion body 11a is rotated by twisting the water injection pipe 12a. The insert 11a rotates in the casing 10a, but the stopper 11c is locked to the co-rotation preventing projection 10d, so that the rotation of the separating portion 11b is prevented. Thereby, the screwing of the separating portion 11b is released with respect to the rotating insert 11a, and the separating portion 11b is separated from the insert 11a as illustrated in FIG. When the separation part 11b is separated from the insert 11a, the water injection pipe 12a can be pulled up on the ground.

  In the present invention, not only when the outer tube 15 is inserted into the vertical hole H, but also when the outer tube 15 is inserted into the oblique hole H or the hole H bent in the middle to be fixed in the ground. Can be applied. Further, the present invention can be applied not only to fix the outer pipe 15 for injecting the ground improvement chemical solution into the ground but also to fix the pipe used for other construction in the ground. For example, in a cylindrical drain construction method, it can be applied to fix a cylindrical drain pipe in the ground.

DESCRIPTION OF SYMBOLS 1 Anchor apparatus 2 Opening-closing blade 2a Protrusion part 2b Auxiliary arm 2c Support shaft 2d Guide support shaft 3 Pressing member 3a Guide protrusion 4 Holding plate 4a Guide hole 5 Support shaft 6 Cylinder 6a Expanding part (outflow part)
7 Piston 7a Concave groove 8 Seal member 9 Cover body 10 Connection part 10a Casing 10b Large diameter cavity part 10c Small diameter cavity part 10d Co-rotation prevention protrusion 11a Insert 11b Separation part 11c Stopper 11d Press ball 11e Spring 11f Flow path 11g Support shaft 12a Water injection pipe 12b Water injection hose 13 Water pressure applying means 14 Water pressure sensor 15 Outer pipe (pipe)
17 Casing rod H Drilling hole

Claims (5)

  In a tubular anchor device for fixing a tubular body inserted into a casing rod provided in a drilling hole in the ground, a cylinder attached to the tip of the tubular body and a rear end of the cylinder are detachably connected. A water injection pipe, water pressure applying means for supplying water into the cylinder through the water injection pipe, a piston that moves inside the cylinder to the cylinder tip side by the water pressure of the supplied water, and a pressure that moves together with the piston to the cylinder tip side An outflow that causes the water in the cylinder to flow out to the outside of the cylinder at a predetermined position of the cylinder, comprising a member, an opening / closing blade that is pressed by the pressing member and spreads in the outer circumferential direction of the cylinder, and a water pressure sensor that detects the water pressure in the cylinder The opening and closing blades are arranged in the cylinder outer peripheral direction before the piston moves to the position where the outflow portion is provided. Tube anchor apparatus characterized by being configured so as to expand at the opening angle.   A holding plate for holding the opening / closing blade vertically is provided, the opening / closing blade is pivotally supported on the holding plate, a guide hole extending in the cylinder axial direction is provided on the holding plate, and the pressing member is provided with the holding plate. The tubular anchor device according to claim 1, wherein a guide protrusion is provided, and the guide protrusion is moved along the guide hole when the pressing member moves.   The tubular body according to claim 1 or 2, wherein the opening and closing blades are covered with a cover body together with the holding plate, and the cover body is cut by the opening and closing blades when the opening and closing blades spread in the cylinder outer peripheral direction. Anchor device.   The tubular anchor device according to any one of claims 1 to 3, wherein the opening / closing blade is provided with a protruding portion protruding from a surface thereof.   In a tube body retaining method in which a tubular body inserted into a casing rod provided in a drilling hole is fixed in the ground, a piston is attached to the distal end portion of the tubular body and moves to the distal end side of the cylinder in the cylinder. And a pressing member that moves to the cylinder tip side together with the piston, and an opening / closing blade that is pressed by the pressing member and spreads in the cylinder outer peripheral direction, and after inserting the tubular body into the casing rod, By supplying water into the cylinder through a water injection pipe detachably connected to the rear end, and by moving the pressing member together with the piston by the water pressure of the supplied water, in the ground at the tip of the casing rod, The opening and closing blades are spread in the cylinder outer periphery direction, and the piston moves to the outflow part provided at a predetermined position of the cylinder. In this case, the water in the cylinder is caused to flow out of the cylinder from the outflow portion, and after the water pressure drop in the cylinder due to the outflow of water is detected by the water pressure sensor, the casing rod is pulled out on the ground. A tubular body retaining method characterized by the above.

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