JP3799499B2 - Ground anchor construction and ground anchor structure using trumpet pipe - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ground anchor construction using a trumpet pipe and a structure thereof.
[0002]
[Prior art]
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, and drilling holes in the base to inject cement mortar etc. 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.
[0003]
As shown in FIG. 7, the general construction method of the ground anchor method is to insert the casing pipe 2 into a drilled hole drilled to a depth to the base, for example, with a rotary percussion drilling machine [FIG. . Then, the grout material G is filled into the casing pipe 2 and the tendon 4 (tensile material) is inserted through the casing pipe 2 as shown in FIG. Next, the grout material G is injected under pressure while the casing pipe 2 is pulled out as shown in FIG. The unstable layer is reinforced by tensioning the tension portion between the anchor body 3 formed in the stable layer in this way and the structure provided on the ground surface [(e)].
[0004]
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.
[0005]
[Problems to be solved by the invention]
As described above, it goes without saying that the most expected effect in adopting the ground anchor method as the slope reinforcing work is that a prestress is applied to the tension portion. However, in the conventional ground anchor construction, the prestress, which is the greatest feature, is hardly structurally applied.
[0006]
This is because the portion of the unstable layer to be compressed is continuously integrated with the anchor body by the injection of the grout material. Such a phenomenon occurs in the casing pressure injection method. Prestress applied to the anchor head is applied to the grout material that has penetrated to the portion to be compressed, and the unstable layer is not damaged unless the grout material in this portion is broken. No compression zone will occur. Even if the grout material breaks, the compression is limited to the fracture locality, and unless the tensile property of the grout material is lost throughout the unstable layer, the substantial function of the ground anchor construction cannot be fully exhibited. .
[0007]
[Means for Solving the Problems]
Therefore, the present inventor has been able to achieve the present invention as a result of intensive studies in view of the above problems, and the feature thereof is that in the ground anchor work, the casing pipe press-fitted into the drilling hole is connected with a tensile material. A trumpet pipe composed of a pipe portion having a gap in between and a diameter-enlarged portion provided at the tip portion of the pipe portion and communicating with the pipe portion is inserted, and the grout material filled in the casing pipe is inserted into the trumpet tube. It is to inject mortars to be solidified after tension of the tensile material into the gap formed on the outer surface side of the pipe part by discharging through the pipe part. (First invention)
[0008]
Or, in ground anchor work, after the grout material is press-fitted into the casing pipe to form the anchor body part in the base, it is provided at the diameter of the pipe part having a gap between the tensile material and the tip part of the pipe part. A trumpet pipe formed by an enlarged diameter portion communicating with the casing pipe is inserted into the casing pipe, whereby the grout material between the casing pipe and the trumpet pipe is discharged through the pipe section of the trumpet pipe, and the casing After pulling out the pipe, an injection pipe filled with mortars is inserted into the gap between the drilling wall and the trumpet pipe. (Second invention)
[0009]
Alternatively, the grout material inserted through the casing pipe and discharged around the tension material tensioned between the anchor body and the surface structure is discharged, and has a diameter having a gap between the tension material. A trumpet pipe formed by a pipe portion and a diameter-expanded portion provided at a tip portion of the pipe portion and communicating with the pipe portion, a grout material between the pipe portion and the tensile material, the pipe portion and a drilling wall, And mortars injected between the two. (Third invention)
[0010]
Here, the “anchor body” in the present specification means that a casing pipe is inserted into a hole drilled by a drilling machine from the ground surface to a depth from the stable base to cement milk or cement mortar in the casing pipe. It refers to a lump formed in the base by press-fitting grout material. There are various hole drilling machines, for example, a rotary percussion type and a down-the-hole hammer type. In the rotary percussion type, the anchor body is formed by press-fitting the grout material while pulling out the casing pipe, but in the down-the-hole hammer type, the anchor forming portion is drilled in a series of processes, and the anchor body is not pulled out. It is formed. In the present invention, since the grout material up to the anchor body is removed by inserting the trumpet pipe through the casing pipe, the anchor body portion may have the same diameter as the casing pipe.
[0011]
“Tensile material” refers to a steel material that is prestressed by embedding one end in an anchor body and pulling the other end from the ground surface side. Generally, a PC steel strand, a PC steel composite wire bundle, a PC steel rod, or the like is used. Usually, a tensile material is covered with a sheath and a rust preventive material such as grease is enclosed inside. Generally, an apartment or a fixed body is called a tendon.
[0012]
“Trumper pipe” refers to a member for discharging a part of the grout material filled in the casing pipe to the outside. This is because the grout material is pressurized and injected into the casing pipe to form the anchor body part, and then the trumpet pipe is inserted into the casing pipe, so that the grout material is brought outside through the inside of the pipe part from the enlarged diameter part. It is for discharging and ensuring that the tensile force of the anchor head is transmitted to the anchor body. The insertion length of the trumpet tube is basically up to the anchor body. That is, the grout material between the casing pipe and the trumpet tube is removed, and the anchor body injection grout material is basically prevented from flowing out to the free length portion.
[0013]
The greatest object of the present invention is to prevent the portion to be compressed of the unstable layer from being continuously integrated with the anchor body by the injection of the grout material, so that no compression region is generated in the unstable layer. On top of that, mortars are injected into the gap formed between the trumpet tube and the drilling wall to further ensure the protection of the tensile material. For these reasons, the trumpet tube is inserted to such an extent that a compression zone is generated in the unstable layer (the length that does not reach the anchor body), and a part of the grout material between the casing pipe and the trumpet tube (of the free length portion) It is also possible to remove only a part of the axial direction.
[0014]
The trumpet tube is constituted by a pipe portion and a diameter-expanded portion provided at and communicated with the pipe portion. The pipe portion is a portion that fits into the tensile material, and the grout material is discharged through the pipe portion. For this reason, let the internal diameter of a pipe part be a diameter which produces a clearance gap between tensile materials. The material is not particularly limited, but it is preferable to reduce the weight with a plastic such as aluminum or polyvinyl chloride.
[0015]
The enlarged diameter portion is provided at the tip of the pipe portion to introduce the grout material in the casing pipe into the pipe portion, and has a truncated cone shape or a bowl shape. The material is made of a soft material such as rubber, leather, synthetic rubber, or synthetic leather, and is made to follow the inner peripheral surface of the casing pipe. It is preferable to remove even the grout material on the inner peripheral surface portion of the casing pipe at the enlarged diameter portion, but even if it remains to some extent, it may be easily broken when the tension material is tightened or removed when the casing pipe is pulled out. Accordingly, the diameter of the casing pipe may be a diameter where a gap is generated, and even when formed of a hard member such as metal or plastic, most of the grout material that hinders the tension of the anchor body can be removed.
[0016]
It is preferable to provide a guide member on the distal end side of the enlarged diameter portion. This is because if there is a portion with a different diameter such as a coupling in the casing pipe, the enlarged diameter portion may be caught and cannot be inserted further. As the guide member, pin-shaped members such as metal and plastic are provided at appropriate intervals. In this case, the guide member is provided so as to be inclined inward so as not to be caught by the different diameter portion, or the tip portion is bent inward.
[0017]
By leaving the trumpet tube in the inserted state, it greatly contributes to rust prevention of the tensile material. In addition, since the grout material remaining between the trumpet tube and the tension material also contributes to the protection of the tension material, the inner grout material does not flow out to the anchor body by a method such as covering the pipe portion after inserting the trumpet pipe. It is preferable to do so. Since the trumpet pipe that has been inserted normally has a pipe portion protruding from the tensile material, the head portion of the tensile material is exposed by cutting the pipe portion after the casing pipe is pulled out. In this case, the pipe portion may have a joint structure, and the joint portion may be removed without being cut.
[0018]
An “injection pipe” is a member that is inserted into a gap formed between a drilling wall and the trumpet pipe by discharging the grout material with the trumpet pipe, and injects mortars such as concrete and mortar. The member for. The injection pipe is inserted after the grout material is discharged by the trumpet pipe and then the casing pipe is pulled out. The injection of mortars is performed to solidify after tension so as not to affect tendon tension. Usually, a pressure receiving plate or a bearing plate is attached and the tendon is tensioned and fixed before injecting. If re-tension is required, infuse afterwards. In addition to injecting and extracting mortars, the injection pipe may be cut and left inside.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on embodiments of the invention shown in the drawings.
[0020]
An example of an embodiment of ground anchor work using a trumpet pipe is shown in FIG. First, a hole for inserting the casing pipe 2 and a hole for forming the anchor body 3 are drilled by a down-the-hole hammer type drilling machine as shown in (a), and the casing pipe 2 and tendon (tensile material) as shown in (b). ) 4 is inserted. Next, the grout material G is pressurized and injected into the casing pipe 2 as shown in FIG. The steps up to here are the same as those of the conventional ground anchor method.
[0021]
When the anchor body 3 is formed, the trumpet pipe 1 is pushed into the casing pipe 2 as shown in (d). By inserting the trumpet pipe 1, the grout material G in the casing pipe 2 is discharged to the outside through the pipe portion 11 of the trumpet pipe 1. After discharging the grout material G, the casing pipe 2 is completely pulled out (e), tensioned (f), and fixed (g) in the same manner as a general ground anchor.
[0022]
An example of the embodiment of the trumpet tube 1 is shown in FIG. The trumpet tube 1 is composed of a pipe portion 11 and an enlarged diameter portion 12 as shown in FIG. 1A, and the distal end portion of the enlarged diameter portion 12 is bent inward as shown in FIG. A plurality of guide members 13 are provided. In this example, an example is shown in which a trumpet tube stopper sheath 14 for processing the head of the trumpet tube 1 inserted is attached. FIG. 2C shows a state in which the trumpet pipe 1 is pushed into the casing pipe 2, and the grout material G that has been stirred by the enlarged diameter portion 12 is discharged through a gap with the tendon 4 inside the pipe portion 11. Indicates the state. Moreover, even when there is a different diameter portion due to the presence of the coupling 21 in the casing pipe 2 as in this example, the enlarged diameter portion 12 can be deformed and pushed in by the guide member 13 as shown by a chain line in the figure.
[0023]
As shown in FIG. 3, the anchor structure constructed by the ground anchor construction using the trumpet pipe has no free length part that inhibits compression by tendon 4, and the tensile force from the tension part is applied to the anchor body 3. It can be transmitted reliably, and secondary tension can be effectively performed.
[0024]
FIG. 4 shows an example of an embodiment of the ground anchor construction using the trumpet pipe according to the first invention of the present invention. The tension is applied by processing the tendon head such as attaching the pressure receiving plate 6 and the bearing plate 7. Let Then, the mortars 8 are injected from the injection pipe 5 inserted into the gap between the drilling wall and the trumpet tube 1. Usually, after the tension, the inspection confirmation such as the settlement of the pressure plate 7 is executed, and when the re-tension is necessary, the mortars 8 are injected thereafter. The injection pipe 5 is cut after injection and left inside, or pulled out while being injected to complete the operation.
[0025]
FIG. 5 shows an example of an embodiment of the ground anchor construction using the trumpet pipe according to the second invention of the present invention. After the casing pipe 2 is pulled out, the gap between the drilling wall and the trumpet pipe 1 is shown. The injection pipe 5 is inserted into the gap. The injection of mortars is not performed at this point, but after the tendon 4 has been reliably tensioned. The injection pipe 5 may be inserted after the casing pipe 2 is pulled out, and may be after the tendon 4 is tensioned and inspected. In this example, the holder 17 is installed in the hole, so that the pipe portion 11 of the trumpet pipe 1 is positioned substantially at the center of the drilling hole. Further, a cap 16 is put on the pipe portion 11 which is the grout material discharge portion 15 of the trumpet tube so that the inner grout material G does not flow out to the anchor body 3 side.
[0026]
The ground anchor structure 30 according to the third aspect of the present invention can cover the periphery of the tendon 4 between the ground structure such as the bearing plate 7 and the anchor body 3 with a plurality of layers. The protective effect of 4 is extremely high. As shown in FIG. 6, this is protected by the pipe portion 11 of the trumpet tube 1, the grout material G remaining between the pipe portion 11 and the tendon 4, and the mortars 8 injected by the injection pipe 5. It will be. Further, since the tendon 4 itself has a structure in which the sheath 42 is filled with a rust preventive agent and covers the tension member 41, not only the effect of preventing the sheath 42 from being damaged due to ground disturbance but also the tension by the sheath 42 damage prevention. This greatly contributes to the rust prevention effect of the material 41.
[0027]
【The invention's effect】
As described above, the ground anchor work and the ground anchor structure using the trumpet pipe according to the present invention are based on the ground anchor work using the trumpet pipe that can reliably apply the prestress to the free length portion. By injecting mortars into the gap created by the insertion, the tendon and thus the tensile material can be protected more reliably, and the original functions of the ground anchor with excellent durability, workability and safety can be fully utilized. be able to.
[Brief description of the drawings]
FIGS. 1A to 1G are schematic side views showing an example of an embodiment of a ground anchor construction using a trumpet pipe.
FIGS. 2A and 2B show an example of an embodiment of a trumpet tube used in the present invention. FIG. 2A is a longitudinal sectional view, FIG. 2B is a perspective view of an enlarged diameter portion, and FIG. It is a schematic sectional drawing which shows an example.
FIG. 3 is a schematic cross-sectional view showing an example of an embodiment of a ground anchor structure that has been passed through a trumpet tube.
FIG. 4 is a schematic cross-sectional view showing an example of an embodiment of a ground anchor construction using a trumpet pipe according to the first invention of the present invention.
FIG. 5 is a schematic cross-sectional view showing an example of an embodiment of a ground anchor construction using a trumpet pipe according to the second invention of the present invention.
FIG. 6 is a schematic sectional view showing an example of the embodiment of the ground anchor structure according to the third invention of the present invention.
7A to 7E are schematic cross-sectional views showing examples of conventional ground anchor methods.
[Explanation of symbols]
G Grout
1 Trumpet pipe
11 Pipe section
12 Expanded part
13 Guide member
14 Trumpet tube stopper sheath
15 Grout material discharge section
16 cap
17 Holder
2 Casing pipe
21 coupling
3 Anchor body
4 Tendon
41 Tensile material
42 sheath
5 Injection pipe
6 Pressure plate
7 Supporting plate
8 Mortars
30 Ground anchor structure

Claims (3)

In the ground anchor work, a trumpet pipe comprising a casing pipe press-fitted into a drilled hole, a pipe part having a diameter having a gap with a tensile material, and a diameter-enlarging part provided at the tip part of the pipe part and communicating with the pipe part Mortars to be solidified after tension of the tensile material is injected into the gap formed on the outer surface side of the pipe part by discharging the grout material filled in the casing pipe through the pipe part of the trumpet pipe Ground anchor construction using a trumpet pipe characterized by that. In ground anchor work, after grout material is press-fitted into the casing pipe to form the anchor body part in the base, it is provided at the pipe part with a diameter having a gap between the tensile material and the tip part of the pipe part and communicates with this By inserting a trumpet pipe constituted by the expanded diameter portion into the casing pipe, the grout material between the casing pipe and the trumpet pipe is discharged through the pipe section of the trumpet pipe, and the casing pipe is A ground anchor construction using a trumpet pipe, wherein an injection pipe filled with mortar is inserted into the gap between the drilling wall and the trumpet pipe after being pulled out. A pipe part with a diameter having a gap between the tension member and the tension member between the anchor body and the ground surface structure, which discharges the grout material inserted and filled in the casing pipe around the tension member. And a trumpet pipe formed by a diameter-increased portion provided at the tip portion of the pipe portion and communicating therewith, a grout material between the pipe portion and the tensile material, and between the pipe portion and the drilling wall And a mortar injected into the ground anchor structure.

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