JPH0330648B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for fixing an anchor by applying tension to a tensile material such as a prestressed steel strand.

<Conventional technology> Conventionally, the VSL construction method includes a movable fixing method (E type) in which tensile material is fixed with wedges.

An example of this fixing technique is shown in FIG.

In the figure, a is the concrete structure, b is the sheath, and c
is a bearing plate installed on the end face of concrete structure a, and d is a tension member made of unbonded type PC steel stranded wire.

Then, after inserting the tensile material d into the anchor hole e and filling it with fixing grout f to secure it to the ground, prestress is applied to the tensile material d, and a wedge piece g is attached to the anchor head h. It has a structure that allows it to be gripped and fixed.

<Problems to be Solved by the Present Invention> When the anchorage ground is an aquifer, pressured ground, etc., the following problems exist.

(a) If anchor hole e is facing downward, anchor hole e
Water accumulates up to the upper part of the inside.

However, with conventional anchor fixing techniques, it has been impossible to remove water i accumulated in anchor holes e without adversely affecting anchor fixing.

(b) If water i accumulated in the anchor hole e is left unattended, it will cause corrosion of the tensile member d, which is fatal to the anchor.

(c) Even after the construction of the anchor is completed, the tensile material d and anchorage will corrode due to the influence of groundwater and seepage water.

<Object of the present invention> The present invention was made to solve the above-mentioned problems, and it is possible to construct an anchor by removing spring water existing in the anchor hole without adversely affecting the strength of the anchor. The purpose is to provide a method for fixing anchors that is possible.

<Structure of the Invention> An embodiment of the present invention will be described below with reference to the drawings.

<1> Drilling of anchor holes (Figs. 1 and 2) Concrete is sprayed or poured onto the spring water ground 1 to construct the concrete structure 11.

At this time, the outer sleeve 12 and the spiral reinforcing bar 2 are buried in concrete at the position where the anchor is to be fixed.

After the curing period of the concrete structure 11 has elapsed,
Using the outer sleeve 12 as a guide, the anchor hole 13 is bored in alignment with the center of the spiral reinforcing bar 2 using a known drilling method.

Further, in the hole opened in the concrete structure 11, an upper communicating path 14 and a lower communicating path 15 are formed independently, respectively, to communicate the inside and outside of the hole.

<2> Anchor insertion set (Figure 3) Insert the tensile material 3 made of unbonded type PC steel stranded wire etc. manufactured on the ground side into the anchor hole 13.

This tensile material 3 is attached to the fixing sheath 3 over the fixing length.
1, and a grout filling hose is installed inside the hole so that the grout material can be discharged at the bottom of the hole.

<3> Fixing grout (Figure 4) Fixing grout material 4 such as cement paste or mortar is placed on the grout filling hose exposed outside the hole.
is pumped to fill the anchor hole 13 from the bottom.

The fixing grout 4 is filled up to the vicinity of the exit of the anchor hole 13 .

As a result, water 5 existing in the anchor hole 13
Although the water 5 is pushed out by the fixing grout 4 and discharged out of the hole, water 5 still remains near the exit of the anchor hole 13 in the outer sleeve 12.

<4> Attaching the water-shielding sleeve (Fig. 5) The free end of the tensile member 3 exposed in the anchor hole 13 is equipped with a bearing plate 61 as shown in Fig. 6, which is called an inner sleeve with both ends open. Insert the waterproof sleeve 6.

[Structure of water-shielding sleeve] The water-shielding sleeve 6 is formed, for example, by fixing a bearing plate 61 to one end of a steel pipe.

The inner diameter of the free end side of the water-shielding sleeve 6 is formed to be somewhat larger than or approximately equal to the outer diameter of the tension member 3 exposed from the fixing grout material 4 (the outer diameter of the fixing sheath 31).

On the inner periphery of the free end of the water-blocking sleeve 6, there is a water-stop ring 62 and a sealing material 6 for both water-stopping and tightening.
3 will be provided.

The water stop ring 62 and the sealing material 63 are water stop materials that are brought into close contact with the outer periphery of the tensile material to form a watertight state, thereby preventing water from seeping into the water shield sleeve 6.

[Structure of the bearing pressure plate] The bearing pressure plate 61 is attached to the side surface of the bearing pressure plate 61 from the outside.
An injection channel 6 is connected to the opening opened at the center of the injection channel 6.
form 4.

Even if the water-shielding sleeve 6 with the above structure is attached to the exposed end of the tension member 3, the water 5 accumulated in the anchor hole 13 will not enter the inside of the water-shielding sleeve 6, and as a result, the water-shielding sleeve The tensile material 3 located inside 6 is completely cut off from contact with water 5.

Note that there is still spring water 5 on the outside of the water shielding sleeve 6.
exists.

<5> Tension The anchor head 7 is brought into contact with one side of the pressure plate 61 and set.

Then, a predetermined tension force is introduced into the tension member 3 while it is in contact with the water 5.

Each PC steel strand protruding from the anchor head 7 is gripped by a wedge piece 8, and the tension member 3 is fixed.

The exposed portion of the tensile material 3 is covered with a protective cap 9 to seal it.

Furthermore, with the tension force introduced into the tensile member 3, the water 5 existing in the anchor hole 13 is completely removed in the next two steps.

<6> Grouting into the Water-shielding Sleeve An annular grout material 41 such as mortar, oil, etc. for corrosion prevention is injected into the water-shielding sleeve 6 through the injection path 64 of the bearing pressure plate 61.

The grout material 41 inside the ring is prevented from leaking out of the ring by a sealing material 63 and a water stop ring 62.

<7> Grouting outside the water-shielding sleeve (No. 1, 7)
(FIG.) Next, an extra-annular grout material 43 for the purpose of fixing mortar or the like is filled into the hole where the water 5 is present via the lower communication path 15.

The water 5 that has nowhere to go due to filling with the extra-annular grout material 43 is pushed out of the hole from the other upper communication path 14.

That is, the present invention adopts a method of draining the water 5 remaining in the anchor hole 13 by replacing it with the extra-ring grout material 43.

In addition, the water stop ring 62 and the sealing material 63 prevent the outer ring grout material 43 from entering into the water shield sleeve 6, and in addition, the filling work of the inner ring grout material 41 is performed in advance. Entry of the external grout material 43 into the water-blocking sleeve 6 can be more reliably prevented.

<Function> Next, the function of the anchor constructed in the above steps will be discussed.

As described above, the water 5 present in the anchor hole 13 can be removed when constructing the anchor.

Therefore, corrosion of the tensile material 3 due to the remaining water 5 can be reliably prevented.

Further, even if a crack occurs in the outer ring grout material 43, the water stop ring 62 and the seal material 63 maintain a watertight state, so that water can be reliably prevented from entering the water shield sleeve 6.

Furthermore, since the inside of the outer sleeve 12 is filled with grout, it is possible to reliably prevent water from entering from outside the hole.

<Effects> Since the present invention is as described above, the following effects can be expected.

(a) By replacing the water in the anchor hole with the grout material, it became possible to fix the grout while removing the water remaining in the anchor hole.

Therefore, if the planned settlement ground is a spring area,
Alternatively, even in cases where the anchor hole crosses a groundwater layer, construction can be performed without affecting the strength of the anchor.

(b) To remove water remaining in the anchor hole,
After inserting the waterproof sleeve into the free end of the tension member,
The process is as simple as injecting grout into the inside and outside of the water-blocking sleeve separately.

[Brief explanation of drawings]

Fig. 1: An explanatory cross-sectional view of the vicinity of the anchor head of the anchor according to the present invention, Figs. 2 to 6: An explanatory view of the method of constructing the anchor, Fig. 7: A perspective cross-sectional view of Fig. 1,
FIG. 8: Explanatory diagram of the prior art.

Claims (1)

[Claims] 1. An anchor hole is opened in the ground, an unbonded type tensile material assembled outside the hole is inserted into the anchor hole, and then grout is injected into the anchor hole to insert the tensile material into the anchor hole. In an anchor fixing method in which tension is applied to the tensile material after fixation, the fixing grout is filled into the anchor hole up to the lower part of the neck of the anchor head, and then the tensile material exposed at the lower part of the neck of the anchor head is After applying tension to the tensile material with the water-tight tube placed around it, a corrosion-resistant material is sealed inside the water-blocking tube, and then the water present in the anchor hole is poured into grout material such as mortar. A method for fixing an anchor, which is characterized by fixing a tensile material by filling a void with grout while displacing the material.