JP4469695B2 - Anchor head and fixing unit construction method - Google Patents

Description

The present invention relates to a method for forming a fixing portion in a ground anchor work and an anchor head attached to an anchor head.

The ground anchor method is a method used to prevent unstable collapse or peeling by bonding unstable ground or rock directly to stable ground or rock. The anchor body is formed by the following three basic elements.
"Anchor head": A part that allows force from the structure to be transmitted to the tension part as a tension force.
"Tensile part": A part that transmits the tensile force to the anchor body in the base.
"Anchor body": A part that transmits the tensile force from the tension part to the base and resists it.

  The main feature of the ground anchor work is a tightening function that presses and stabilizes the slope where there is a risk of slipping by prestressing the tension part. The tensile strength of the tensile part is used to prevent the landslide mass from trying to slide, but unlike the pile work, by applying a certain amount of prestress to the tensile part at an early stage, the elongation of the tensile part ( There is an initial detent function that can increase the deterrent effect when the amount of deformation due to landslide is small. In addition, there is a sewing function in which the anchor body is formed across the sliding surface and the strength of the sliding surface is increased by the tensile strength of the tensile portion.

In such a ground anchor construction, maintenance by periodic inspection is an essential requirement, and it is necessary to maintain its effect by re-tensioning. For example, due to deformation of the pressure receiving plate or ground subsidence, a tightening effect or a retaining effect that suppresses ground fluctuation is not sufficiently exerted on the anchor body. For this reason, as disclosed in Patent Document 1, for example, there is a fixing unit structure that compensates for a decrease in tension of the anchor body over time by disposing an elastic member in the fixing unit.
JP 11-03941 A

However, the conventional fixing unit structure is merely a structure in which an elastic member is disposed in the fixing unit of the anchor head, and there is a problem that workability for constructing the fixing unit in the field is significantly reduced. For example, there are not only the incorporation of an elastic member in the field and the rust prevention treatment thereof, but also the compression of the elastic member and the increase of the tensile stroke accompanying the tension work of the anchor head. In addition, it may be necessary to introduce a large hydraulic jack.

  In view of the above problems, the present inventor has achieved the present invention as a result of earnest research, and the feature thereof is an apparatus that constitutes the anchoring portion of the anchor head in the ground anchor work. The insertion member for inserting the tendon in the center, and an accommodation member that accommodates an elastic body around the insertion portion, and a cover member that generates a spring effect by the elastic body between the accommodation member, A fixing portion for fixing the housing member and the cover member in a state where the elastic body is compressed is provided.

  Alternatively, in the ground anchor method, a method for constructing a fixing portion in which the anchor head is tensioned and fixed, and a storage member that has an insertion portion that allows a tendon to be inserted in the center and that houses an elastic body around the insertion portion. And an anchor head constituted by a cover member that generates a spring effect by the elastic body with the housing member, the anchor head in a state where the housing member and the cover member are fixed and the elastic body is compressed. After being attached to the part, the fixing of the housing member and the cover member is released.

  Here, the “fixing part” in the present specification is connected to an anchor body formed by drilling to a depth from the ground surface to a stable base, and is maintained in a state in which a tensile part is prestressed. A structure built on the surface of the earth for the purpose. Usually, a pressure receiving plate or a supporting plate is provided on the ground surface, and the head of a tension material (tendon) connected to the anchor body is tensioned with a hydraulic jack and fixed with a fixing tool such as a nut.

  The “accommodating member” refers to a member that has an insertion portion through which tendon is inserted in the center and accommodates an elastic body around it. In this invention, it is set as the structure which generate | occur | produces the spring effect by an elastic body between this accommodating member and this cover member by covering this accommodating member with a cover member. Examples of the elastic body include a coil spring, a disc spring, a gas cushion, and hard rubber such as urethane. These elastic bodies are fitted into the insertion portion of the housing member, or a plurality of these elastic bodies are disposed around the housing. The housing member and the cover member are made of a metal such as stainless steel or aluminum, or a composite material such as plastic or FRP.

  The anchor head according to the present invention is inserted into the tendon or attached to the top of the tendon, thereby supplementing the retention and reduction of the prestress applied to the tensile material by the elastic body. When inserting through the tendon, the cover member is also provided with an insertion portion. When attaching to the top of the tendon, it is possible to attach it after the anchor head is tensioned and fixed, and an engagement part that engages with the end of the tendon is provided at the center of the inner surface of the cover member, or an insertion part is provided. Secure with a nut. It can also be fixed to a fixing tool such as a nut with a bolt.

  In this invention, the fixing | fixed part which fixes a cover member and an accommodating member in the state which compressed the elastic body is provided. After fixing these to the anchor head, the fixing by the fixing portion is released. In other words, it is fixed at the time of factory shipment, and is released after installation at the site. Examples of the fixing part include insertion of pins and bolts, and engagement by hooks. The fixing by the fixing portion is preferably provided at a position where the housing member and the cover member do not move in the axial direction when the fixing is released. This is a structure in which the cover member and the housing member abut each other in the axial direction in a state where the elastic body is compressed, and a fixing portion is provided at a position where these abut each other. And it can achieve by attaching so that both an accommodation member and a cover member may not be opened at the time of fixed release. As a result, the fixation can be easily released, and damage and danger of each part due to a rapid restoring force of the elastic body can be prevented. Further, by providing and fixing the fixing portion at this position, the cover member and the housing member are integrated to form a rigid body, which is also effective when it is attached to the anchor head and then tensioned.

The anchor head according to the present invention has a structure in which the anchor function is maintained by the elastic body by being attached to the anchor head, but the elastic body has been displaced, or the elastic body has been damaged and no longer functions. It is preferable to provide a switch such as a sensor for detecting the above. In particular, by detecting that the elastic body is displaced within the allowable displacement, the anchor function can be repaired and repaired in advance without abruptly decreasing. Means for displaying the detection include lighting of a warning lamp, sound, and transmission by a transmitter.

  The anchor head according to the present invention is not only capable of maintaining the anchor function in the ground anchor work over a long period of time by being configured by the housing member and the cover member provided with the fixing portion that fixes the elastic body in a compressed state, It became possible to remarkably improve the workability, such as eliminating the need to compress the elastic body on site and making it easier to handle.

In particular, when the anchor head is in tension / fixed state, when the cover member and the housing member are released from fixation, they are fixed at a position where they do not move in the axial direction. In addition, fixing can be easily performed. For this reason, it has a very useful effect in practice, such as being able to be mounted on an existing anchor head as an anchor cap that covers the anchor head after tension and fixation.

A housing member that has an insertion portion for inserting tendon in the center and that houses an elastic body around the housing; and a cover member that covers the housing member and generates a spring effect by the elastic body between the housing member, A fixing portion for fixing the cover member and the housing member in a state where the elastic body is contracted is provided.

  FIG. 1 shows an embodiment of an anchor head 1 according to the present invention. The anchor head 1 is composed of a housing member 2 for housing a plurality of coil springs S and a cover member 3 for covering the housing members 2. This is a structure provided with a fixing portion 4 for fixing the cover member 3 and the housing member 2 in a contracted state. The housing member 2 has an insertion portion 21 through which the tendon 5 is inserted at the center, and houses a plurality of coil springs S (12 in this example) around the insertion portion 21. A spring guide 22 is erected in the housing portion to hold each coil spring S. As a means for holding the coil spring S so as not to move, at least one of the cover member 3 and the housing member 2 may be provided with a recessed portion and fitted.

The cover member 3 and the housing member 2 are fixed by the fixing portion 4 in a state where the coil spring S is compressed as shown in FIG. In this example, the fixing screw 41 is fixed by being screwed into four places around the housing member 2. In a state in which these are fixed, the upper end portion of the housing member 2 contacts the inner top surface of the cover member 3. The anchor head 1 of this example is provided with a screw hole 23 to be screwed into a tendon end (apartment) at the center of the inner surface of the cover member 3 for the purpose of being used as an anchor cap that is attached to the anchor head and protects the fixing portion. ing. Further, an O-ring is provided on the peripheral surface of the housing member 2 for the purpose of preventing water from entering the inside.

This anchor cap is attached after the anchor head is tensioned and fixed. The ground anchor is a structure that stabilizes the unstable layer by applying prestress between the anchor body 7 formed on the stable base as shown in FIG. 3A and the fixing part constructed on the ground surface. is there. The anchor head 1 according to the present invention is attached by screwing a screw hole 23 into an apartment of the anchor head as shown in FIG. After the mounting, the fixing screw 41 fixing the cover member 3 and the housing member 2 is removed, and the process is completed. Since the bottom of the housing member 2 is in contact with the support plate 6, the unlocking operation for removing the fixing screw 41 can be performed very easily without being affected by the coil spring S that has been compressed and stored. After removing the fixing screw 41, the opening is preferably filled with a waterproof caulking material.

FIG. 4 shows another embodiment of the anchor head 1 according to the present invention, which has a structure in which it is tensioned after being attached to the anchor head. Since the anchor head 1 is fixed by bringing the upper end portion of the housing member 2 into contact with the inner top surface of the cover member 3, the anchor head 1 can be easily handled as one member. This may be inserted into the tendon 5 to be tensioned and fixed in the same manner as before, and then the fixing screw 41 is removed to complete the mounting.

  FIG. 5A shows still another embodiment of the anchor head 1 according to the present invention, and has a structure in which an anchor cap 8 with an alarm device is attached. This anchor cap 8 with an alarm device is a device that turns on a warning lamp 82 when the switch 81 provided on the tendon 5 is brought into contact with the pressure bearing plate 6 so that it is separated, and operates with a battery or solar cell as a power source. To do. Although the anchor function 1 can be maintained for a long time by the anchor head 1 with a built-in elastic body, by providing the anchor cap 8 with a warning device, it can be grasped as visual information that ground subsidence has occurred, and is maintained and managed. Function can be enhanced. In this example, the switch 81 is in contact with the bearing plate 6 but may be in contact with the housing member 2.

FIG. 6B shows a structure in which the switch 81 is built in the cover member 3 and is operated by an operating portion 83 provided in the housing member 2. In this way, the operating position can be adjusted according to the type, size, and number of elastic bodies. The adjustment of the operation position is performed at the attachment position of the operation unit 83 and the switch 81. An O-ring may be used as the operating unit 83. In this example, four switches 81 are provided around the cover member 3 for detection. However, since the detection of the relative movement of the cover member 3 and the housing member 2 (or the bearing plate 6) cannot detect the breakage or impossibility of the elastic body, the position of FIG. A switch 81 for contact may be provided.

FIG. 6A shows still another embodiment of the anchor head 1 according to the present invention, in which urethane rubber 9 is used as an elastic body. The urethane rubber 9 has a ring shape and is provided so as to be fitted into the insertion portion 21 of the housing member 2. Further, in FIG. 2B, two disc springs 10 are provided so as to be fitted into the insertion portion 21.

It is sectional drawing which shows one Example of the anchor head which concerns on this invention. Example 1 It is sectional drawing which shows the state which fixed the anchor head shown in FIG. 1 with the fixing | fixed part. (A) is a schematic sectional drawing which shows one Example of the anchor structure constructed by ground anchor construction. (B) is a schematic sectional drawing which shows the state which attached the anchor head which concerns on this invention to the anchor head of (a). (Example 2) It is sectional drawing which shows the other Example of the anchor head based on this invention. (Example 3) (A) (b) is sectional drawing which shows the further another Example of the anchor head based on this invention, respectively. Example 4 (A) (b) is sectional drawing which shows the further another Example of the anchor head based on this invention, respectively. (Example 5)

Explanation of symbols

S Coil spring 1 Anchor head 2 Housing member
21 Insertion section
22 Spring guide
23 Screw hole 3 Cover member 4 Fixing part
41 Fixing screw 5 Tendon 6 Bearing plate 7 Anchor body 8 Anchor cap with alarm device
81 switch
82 Warning light
83 Actuator 9 Urethane rubber 10 Disc spring

Claims (3)

In ground anchor work, an apparatus that constitutes a fixing portion of an anchor head, a housing member that has an insertion portion through which a tendon is inserted in the center, and that houses an elastic body around the insertion portion, and the storage member And a cover member provided at the center of the inner surface for engaging and fixing the end of the tendon to generate a spring effect by the elastic body, and the accommodating member in a state in which the elastic body is compressed And an anchor head provided with a fixing portion for fixing the cover member. In ground anchor work, an apparatus that constitutes a fixing portion of an anchor head, a housing member that has an insertion portion through which a tendon is inserted in the center, and that houses an elastic body around the insertion portion, and the storage member And a cover member that generates a spring effect by the elastic body, and a switch for detecting movement in the urging direction by the elastic body is provided on either the cover member or the housing member, An anchor head comprising a fixing portion for fixing the housing member and the cover member in a state where the elastic body is compressed.   In the ground anchor construction, a method for forming a fixing portion in which the anchor head is tensioned and fixed, and a storage member that has an insertion portion that allows a tendon to be inserted in the center and that houses an elastic body around the insertion portion, An anchor head constituted by a cover member that generates a spring effect by the elastic body with the housing member is fixed to the anchor head with the housing member and the cover member fixed and the elastic body compressed. After fixing, the fixing member is released from the fixing of the housing member and the cover member.

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