JPH0619138B2 - Method of forming a sliding layer in underground buried objects - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for forming a sliding layer on an underground buried object, which is an underground buried object such as a foundation pile, a steel sheet pile or an underground structure set in the ground. The present invention relates to a method for forming a sliding layer on the.

[Prior art] Foundation piles set in the ground, steel sheet piles, and other underground structures buried underground are generally subjected to the shear stress generated by soil consolidation when set in the ground. It is known to form a sliding layer on the surface of

Conventionally, for foundation piles, a method of melt-coating asphalt with a sliding layer in a factory or forming a sheet by spirally adhering a sheet-shaped product to the entire circumference is known, and also for underground structures. In the case of a vertical wall surface, a method of melt-bonding a sheet provided with a sliding layer with a propane burner is known.

[Problems to be solved by the present invention] However, the foundation piles are transported in the factory to process the sliding layer,
It is difficult to store, and especially in summer, the sliding layer is liable to fall off, so it is desirable to perform on-site construction as much as possible.

In addition, to form a sliding layer on the vertical wall of the underground structure,
Since it is necessary to arrange the joining line for the sheet by using the butt joint joining method, it is difficult to adopt the propane burner welding method.

The present invention, as a result of research for improving the above-mentioned conventional drawbacks,
An object of the present invention is to provide a method capable of easily and reliably forming a sliding layer on an underground buried object.

[Means for Solving the Problems] The present invention relates to an adhesive layer of rubber asphalt compound,
A first step of sequentially laminating a sliding layer of an asphalt compound and a surface protection layer such as a woven fabric or a non-woven fabric to form a sheet; a second step of cutting the sheet obtained in the first step into a rectangle; The adhesive layer surface of the rectangular cut sheet obtained in the two steps is crimped to the adherend surface of the foundation pile, steel sheet pile or underground structure, and at the same time, the end faces of the adjacent sheets are connected by the butt joint joining method. This is a method of forming a sliding layer on an underground buried object consisting of a third step.

In addition, the rubber asphalt compound forming the adhesive layer is a mixture of straight asphalt and SBS synthetic rubber, and has a larger stiffness coefficient than straight asphalt.

[Operation] The present invention has the above-described structure, and since the adhesive strength between the sliding asphalt and the adherend is poor, when the shear stress acts, the sliding layer is displaced at the same time. It is considered that there is a high probability that displacement will also occur on the adhesive surface.

The inventor has the function of the sliding layer to reduce the shear stress, which is inversely proportional to the stiffness coefficient, while the adhesive strength of the adhesive layer is proportional to the stiffness coefficient. Therefore, when the sliding layer and the adhesive layer are the same layer, It is considered that the adhesive strength is poor and the displacement for reducing the shear stress in the sliding layer may occur at the adhesive surface at the same time.

Therefore, the present invention selects asphalt compound having a small stiffness coefficient under long-term load for the sliding layer, and a rubber asphalt compound having a large stiffness coefficient under long-term load to the adhesive layer to some extent, and excellent adhesiveness, and further sliding. It is necessary to suppress the temperature rise due to exposure during storage and curing during the period until the layer is formed and set in the ground.

In the first step of the present invention, a sheet is formed by sequentially laminating an adhesive layer of rubber asphalt compound, a sliding layer of asphalt compound and a woven or non-woven fabric.

In this case, since both the adhesive layer and the sliding layer are mainly made of asphalt compound, the two layers are well joined at the time of production, and the woven fabric and the non-woven fabric are also well joined.

Also, since the surface protective layer is woven or non-woven fabric, it is possible to suppress temperature rise due to exposure during storage and curing.
Since the surface protective layer can follow the deformation caused by the distortion of the sheet itself during the storage of the sheet or during the construction, the sheet is not distorted and the sliding layer is not wrinkled.

Next, as a second step, the sheet is cut into a rectangle,
Further, as the third step, the adhesive layer surface of the sheet cut in the rectangular shape obtained in the second step is pressure-bonded to the underground buried object, and at the same time, the adjacent sheet end surfaces are connected by the butt joint joining method. The sliding layer can be formed easily.

In the second step, the sheet is cut into a rectangular shape, which is convenient for handling such as transportation, and since the surface protective layer is a woven or non-woven fabric, it can be stored between the protective layer and the sliding layer even when stacked and stored. It does not cause distortion and does not cause wrinkles in the sliding layer.

The adhesive layer of the rubber asphalt compound has an extremely small adhesive area at the beginning because an air film is formed at the interface when pressure-bonded to the steel surface or concrete surface, but the air bubbles become finer with the passage of time and become complete after 7 to 14 days. It has been found by a number of experiments that the entire area of the adhesive adheres to the adherend, and it is estimated that almost 100% of the adhesive surface and the adherend under earth pressure are adhered to each other. It

However, under a long-term load, for example, under a load of 1 year, assuming that the adhesive strength is a tensile speed → 0, the adhesive work is 10 ² to 10 ³ erg / cm.
^It was found from the order of ² and the literature, but the adhesive layer has a thickness of 1 mm,
Assuming a displacement of 1 mm, the rubber asphalt compound has a stiffness coefficient (loading time of 1 year at 20 ° C.) of 4.5 × 10 ⁴ N / m ^{2 and} a calculated adhesive strength of about 150 g / cm ² .

The sliding layer has a thickness of 4.5 mm and a stiffness coefficient of 8 N / m ² (20 ° C
When the consolidation settlement of soil is 100 mm with a loading time of 1 year), the calculated shear stress will be reduced to 0.6 g / cm ² .

From the above calculated values, it can be estimated that even if shear stress acts on the sliding layer, the adhesive surface hardly changes and only the sliding layer changes uniformly.

Therefore, the adhesive layer of the sheet used in the method of the present invention has a sufficient adhesive strength, while the sliding layer smoothly reduces the shear stress generated by the consolidation subsidence of the soil, so that the displacement occurs uniformly. Conceivable.

Example FIG. 1 shows an example of the sheet obtained in the first step of the present invention. In the first step, a rubber asphalt compound adhesive layer (2) is formed on one surface of the asphalt compound sliding layer (1). ) Is laminated, a polypropylene non-woven fabric (3) is laminated on the other surface, and a release paper (4) is laminated on the other surface of the adhesive layer (2) to produce the sheet (S). The shape and thickness of each layer are as follows.

I. Properties 1) Sliding layer Penetration (25 ℃) 35 ± 5 Softening point 75 ± 5 ℃ Low temperature flexibility ＋ 5 ℃ or more Stiffness coefficient (20 ℃ × 1 year) 8N / m ² 〃 (20 ℃ × 30 days) 9 × 10 N / m ² 〃 (20 ° C × 10 ^-2 seconds) 1.5 × 10 ⁷ N / m ² 2) Adhesive layer Penetration (25 ° C) 55 ± 5 Softening point 100 ± 5 ° C Low temperature flexibility −20 ° C Stiffness coefficient (20 ℃ × 1 year) 4.5 × 10 ⁴ N / m ² 〃 (20 ℃ × 30 days) 6.0 × 10 ⁴ N / m ² 〃 (20 ℃ × 10 ^-2 seconds) 2 × 10 ⁵ N / m ² 3) Polypropylene nonwoven fabric Weight 100 g / m ² Tensile strength 21 kg / 5 mm longitudinal 9.0 kg / 5 mm Tensile elongation 30% longitudinal 45% Tear strength 3.5 kg lateral 3.0 kg II. Thickness Sliding layer 4.5 mm Adhesive layer 1.0 mm Non-woven fabric 0.6 mm Release paper 0.2 mm Total 6.3 mm Experimental example The sheet used in the present invention is pressure-bonded to a vertical concrete wall and left for about 20 months, but it is completely adhered and does not peel off . At this time, a load of 6.0 kg / m ² of its own weight acts, but it was confirmed that the adhesive layer firmly adhered.
Further, when the sheet was peeled off and the adhesion was observed on the adhesion surface, it was confirmed that the entire surface was adhered.

Example 1 Figures 2 and 3 show PC concrete piles (diameter 600m
m, length 5m) (P), showing the state where the end faces of the rectangular sheet (S) obtained in the second step, which are adjacent to each other, are connected by the butt joint joining method and crimped. So, apply the pre-rubber rubber asphalt primer (5) to the entire surface of the PC concrete pile (P) at a coating amount of 100 g / m ² , and after confirming the drying, put the release paper (4) on the sheet (S). After peeling, the pressure-sensitive adhesive layer (2) of the sheet (S) was pressure-bonded so that the joining line (6) was aligned.

Drive into the ground with a hitting machine with a curing time of 4 hours or more.
Finish the pile driving by connecting 5 PC concrete piles (P). The casting was done without any problems.

Example 2 FIG. 4 shows a sheet (S) cut into a rectangle (size 1 m ×) obtained in the second step after applying the pre-rubber rubber asphalt primer (5) to the concrete vertical wall (C). 1 m) release paper (4) is peeled off, and they are adjacent to each other as in Example 1 (S).
The end faces were connected by the butt joint joining method and pressure-bonding was performed on the adhesive layer surface. There is no risk of peeling if the pressure bonding is performed sufficiently, and there was no abnormality even when the work area was 1,200 m ² .

INDUSTRIAL APPLICABILITY The present invention can be easily constructed on site and is particularly suitable for underground construction of landfills and soft ground, and its applicable range is as follows.

(1) To reduce the negative friction force.

a. Form a sliding layer on foundation piles, steel piles and PC concrete.

b. Form a sliding layer on the welded joint of the buried object.

c. Form a sliding layer on one or both sides of the steel sheet pile.

(2) To reduce shear stress accompanied by differential settlement prevention.

a. Form a sliding layer on the vertical wall of the underground buried object.

b. Form a sliding layer on the vertical wall of the common groove.

c. Form a sliding layer on the vertical wall of the culvert box.

In order for the sliding layer to work normally, it is necessary to secure the adhesion to the adherend. In particular, in order to prevent uneven settlement, the construction area is wide, so it is necessary to strictly control the tolerance of verticality and smoothness of the underlying construction surface, but the sliding layer of the sheet used in the present invention is 4 mm or more. The thickness is sufficient. Further, in the above-mentioned Examples 1 and 2, the primer layer (5) is previously formed on the adherend surface when the sheet is pressure-bonded, but the primer layer is not always necessary and the adherend surface is a rough surface. It is sometimes used, and may be omitted when the surface is relatively smooth.

[Advantages of the Invention] As described above, the present invention provides a rubber asphalt compound adhesive layer, an asphalt compound sliding layer, a woven fabric, a non-woven fabric surface protective layer in the first step in forming a sliding layer on an underground buried object. A sheet is laminated to form a sheet, the sheet is cut into a rectangle in the second step, and the adhesive layer surface of the sheet cut in the second step is pressed onto the adherend surface of the underground buried object in the third step. At the same time, since the adjacent sheet end faces are connected by a butt joint joining method, construction at the site can be easily achieved, and since the sliding layer has a stiffness coefficient smaller than that of the adhesive layer, the adhesive layer on the adherend has nothing to do with it. It is possible to surely form a proper sliding layer without affecting.

[Brief description of drawings]

FIG. 1 is a sectional view of an example of a sheet used in the present invention, FIG.
The figure is an explanatory view of the state in which the sheet of Fig. 1 is attached to the PC concrete pile by the butt joint joining method, Fig. 3 is an enlarged sectional view in which a part of Fig. 2 is cut away, and Fig. 4 is a vertical view of an underground buried object. It is explanatory drawing at the time of constructing the sheet of FIG. 1 on a wall surface by a butt joint joining method. 1 …… Sliding layer 2 …… Adhesive layer 3 …… Nonwoven fabric 4 …… Release paper 5 …… Rubber asphalt primer

Claims (1)

[Claims] 1. A first step of forming a sheet by sequentially laminating an adhesive layer of rubber asphalt compound, a sliding layer of the asphalt compound and a surface protective layer made of woven or non-woven fabric, and obtained in the first step. The second step of cutting the sheet into a rectangle, and the adhesive layer surface of the rectangular sheet obtained in the second step is pressure-bonded to the adherend surface of the underground buried object, and at the same time, the adjacent sheet end surfaces are butt-jointed A method of forming a sliding layer on an underground buried object, which comprises the third step of connecting with the above.