JPH08296245A - Coated steel manhole - Google Patents

Abstract

PURPOSE: To provide a coated steel manhole which is supported by a ground support layer, minimized in the surface resistance to the sliding of soft ground, and excellent in corrosion preventing property. CONSTITUTION: A steel lid 7 is mounted, through a concrete coping 6, on the upper part of a steel structure having a steel pipe pile 1 driven to a ground support layer 9 through a soft ground 8, the steel pipe pile 1 having a polyolefin coating 4 on the outer surface upper than the support layer 9; and a steel pipe or square steel pipe 2 constituting a manhole body, the steel pipe or square steel pipe 2 being connected to the upper end of the steel pipe pile 1, and having the polyolefin coating 4 on the outer surface and a thermosetting resin coating 5 such as epoxy or polyester on the inner surface. Thus, a highly durable manhole which is minimized in sliding resistance with soft ground to exhibit an earthquake resistance such that the earthquake thrust can be reduced, and improved in corrosion preventing property can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel manhole having an inner surface and an outer surface coated with a coating, and more specifically, it has a small sliding resistance with soil constituting soft ground and is excellent in corrosion resistance. Regarding steel manholes.

[0002]

2. Description of the Related Art In urban development, complete water supply and sewerage are indispensable for civic life. In the construction of this water and sewage system, maintenance of the piping system, cleaning of the pipeline, and installation of manholes for draining rainwater are indispensable. Manholes are also used for maintenance and inspection of gas and electricity supply piping systems.

Therefore, when installing a manhole, in consideration of the ease of maintenance and inspection and pipe cleaning work,
Although various manholes using concrete have been proposed, a method of fixing them in the ground by gravity of concrete is adopted because of the ease of installation work.

[0004]

By the way, in soft ground made of clay particles, silt particles, sand particles, etc., such as landfills in coastal areas, the ground tends to slide in the event of an earthquake. In particular, concrete has a large surface resistance with these grounds, and therefore, when the soft ground slides on a large scale, the manhole moves in the conventional manhole simply supported by the soft ground by gravity.

Therefore, strain stress concentrates and breaks at the connecting portion with the connected pipe, and it becomes impossible to supply water, gas, etc., and the sewer pipe line is blocked, which seriously hinders citizens' lives. That is, in soft ground made of clay particles, silt particles, sand particles, etc., it has been desired to realize a manhole capable of resisting sliding of soft ground.

In view of the above problems, an object of the present invention is to provide a manhole made of coated steel, which supports the manhole itself with a ground support layer, has a small surface resistance against sliding of soft ground, and is excellent in corrosion resistance.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, the present inventors have found that the manhole is firmly supported even when the soft ground is sliding and that the manhole slides with clay, silt or sand constituting the soft ground. The present invention has been accomplished by intensively studying a coating material having low resistance and excellent anticorrosion property, and as a result, found that the above problems can be solved.

That is, according to the present invention, as shown in FIG. 1, a steel pipe pile 1 which penetrates the soft ground 8 and is driven into the ground support layer 9 as well.
Has a polyolefin coating 4 on the outer surface above the ground support layer, and a steel pipe or square steel pipe 2 having a diameter larger than this is connected to the upper end of the steel pipe pile 1, and the body portion of the steel pipe or square steel pipe 2 is connected. Is connected to a flange portion 3 with a steel pipe having a small diameter, the outer surface of the steel pipe or the square steel pipe 2 and the flange portion is provided with a polyolefin coating 4, and the inner surface is covered with epoxy,
This is a coated steel manhole characterized in that a steel lid 7 is attached to an upper portion of a steel structure coated with a thermosetting resin 5 such as polyester through a concrete coping 6.

[0009]

The present invention will be described in detail below.

In constructing the manhole of the present invention, FIG.
First, the steel pipe pile 1 having the polyolefin coating 4 shown in 1 is driven into the ground. Separately, the remaining manhole body portion 10 excluding the concrete coping 6 and the steel lid 7 is manufactured by applying the inner surface coating 5 and the outer surface coating 6, and is connected to the upper end of the steel pipe pile 1 cast on site. Next, concrete coping 6 is applied to the upper part of the concrete, and a steel lid 7 is attached.

Therefore, in order to weld and join the on-site connecting portion, the outer surface of the portion having a length of about 500 mm from the upper end of the steel pipe pile 1 is not previously covered, but is welded and bonded to the manhole body. In addition, the bottom plate of the manhole body part has 2
A skirt portion 11 having a length of about 50 mm is attached by welding, and this portion is not coated in advance and is coated on the spot after welding and joining with the steel pipe pile 1.

The steel material used in the present invention and the steel pipe pile 1 will be described below.
The part, the manhole body part 10, the on-site connection of both, and the concrete coping 6 and the steel lid 7 on the upper part will be sequentially described.

The steel plate used in the present invention, the square steel pipe, the steel plate used for manufacturing the flange and the lid are steel materials made of alloy steel such as carbon steel and stainless steel. As a steel pipe manufacturing method, a UO steel pipe that is manufactured by welding and joining a thick plate into a tubular shape by a U press and an O press, a spiral steel pipe and a steel ingot billet that are manufactured by welding joining a hot rolled steel sheet in a spiral shape. It is possible to use steel pipes such as seamless welded steel pipes that are hollowed out and hot-rolled steel plates that are roll-formed and then welded by electric resistance welding.

As the square steel pipe, the above-mentioned steel pipe formed by a square press into a square tube shape, or a steel sheet cut and welded and processed into a square tube shape can be used. Clad steel pipe or clad, in which the main part is carbon steel, and the inner and outer surfaces of the steel pipe and the front and back surfaces of the steel plate are laminated with stainless steel, metal such as titanium, aluminum, nickel, or alloy steel such as nickel-chromium-molybdenum alloy. Steel plates can also be used.

On the inner and outer surfaces of the steel pipe made of carbon steel, and the front and back surfaces of the steel plate, metal plating of zinc, aluminum, chromium, etc., zinc-aluminum, zinc-nickel,
It is also possible to use a steel pipe or a steel plate which is alloy-plated with zinc-nickel-chromium or the like, or metal-plated or alloy-plated with a dispersion material such as silica or titanium oxide.

Before the polyolefin coating is applied to the steel pipe pile 1 used in the present invention, scales, oils and the like on the outer surface of the steel pipe are removed by blasting, pickling or degreasing, and chromate treatment is applied as a base treatment. The chromate treatment is performed by applying a chromate treatment agent with a roll or brush and then heating and baking.

The chromate-treating agent is, for example, an organic reducing agent or the like added to an aqueous solution of chromic anhydride and heated to partially reduce a portion of hexavalent chromium in the aqueous solution to trivalent chromium. Is added and dispersed, or an organic reducing agent is added to a mixed aqueous solution of chromic anhydride and phosphoric acid and heated to form a reduced aqueous solution in which a part of hexavalent chromium in the aqueous solution is partially reduced to trivalent chromium. A mixture in which fine particles of silica are added and dispersed is used.

In the steel pipe pile 1 used in the present invention, in order to firmly adhere the polyolefin coating to the outer surface of the steel pipe subjected to the surface treatment, the outer surface of the steel pipe subjected to the surface treatment is first coated with an epoxy primer. As the epoxy primer, for example, a mixture of epoxy, pigment and curing agent is used. As the epoxy, for example, diglycidyl ether of bisphenol A or diglycidyl ether of bisphenol F is used.

As the pigment, fine particle powder such as silica or titanium oxide is used. The amount of the pigment added is 100
Good adhesion is obtained in the range of 3 to 30 parts by weight with respect to parts by weight.

Further, the curing agent may be an alicyclic amine such as 3,9-bis (3-aminopropyl) -2,4,8,10-tetraoxaspiro (5,5) undecane butylglycidyl ether adduct. , Aromatic amines such as condensates of metaxylenediamine and epichlorohydrin, and dicyandiamide can be used.

When an alicyclic amine or aromatic amine is used as the curing agent, the curing agent is added in a ratio of the epoxy equivalent of epoxy to the active hydrogen equivalent of the curing agent. When dicyandiamide is used as the curing agent, modified imidazole is added as a curing accelerator to reduce the curing temperature.

Examples of the modified imidazole include 2-
Methylimidazole, 2-phenylimidazole, etc. can be used. In this case, the composition of the curing agent is epoxy 10
3 to 10 parts by weight of dicyandiamide to 0 parts by weight,
When 1 to 3 parts by weight of modified imidazole is added, good adhesiveness can be obtained.

The application of the above-mentioned epoxy primer is carried out by preheating the steel tube subjected to the above-mentioned base treatment by high-frequency induction heating or burner heating, and then spray-coating, roll-coating or brush-applying the epoxy primer on the outer surface thereof, but at room temperature. After the epoxy primer is applied to the outer surface of the steel pipe subjected to the base treatment by these methods, the steel pipe may be preheated to cure the epoxy primer layer.

In any of the methods, good adhesion can be obtained when the preheated temperature of the steel pipe subjected to the base treatment is about 140 to 250 ° C. The thickness of the epoxy primer is 30 to 2
Good adhesion is obtained when it is about 50 μm.

In the steel pipe pile 1 used in the present invention, a modified polyolefin is interposed between both layers in order to firmly bond the epoxy primer coating and the polyolefin coating.
As the modified polyolefin, ethylene homopolymer or a polyolefin composed of ethylene and an α-olefin copolymer such as propylene, butene-1,4-methylpentene-1, hexene-1 or octene-1, and maleic anhydride or A modified polyolefin obtained by addition reaction with an acid anhydride such as itaconic anhydride is used.

The addition rate of maleic anhydride is from 0.05 to
Good adhesion is obtained in the range of 0.5% by weight. These modified polyolefin adhesives are extrusion-coated and laminated on the outer surface of a steel pipe coated with an epoxy primer layer by a T die or a round die. When the thickness of the modified polyolefin adhesive layer is about 100 to 500 μm, good adhesiveness can be obtained.

The outermost layer of the steel pipe pile 1 used in the present invention is coated with polyolefin in order to reduce sliding resistance with clay, silt and sand and to impart corrosion resistance. As the polyolefin, ethylene homopolymer, or ethylene and propylene, butene-1,4-methylpentene-1, hexene-
A mixture of a pigment and a polyolefin such as an α-olefin copolymer such as 1 or octene-1 is used.

The thickness of the polyolefin layer is 1 to 10 mm
When the amount is small, good slidability with clay, silt, and sand can be obtained, and scratches on the coating during casting can be reduced.

In the manufacture of the manhole body portion 10 of the present invention, first, a steel plate is welded to the bottom of a steel pipe or a square steel pipe having a diameter larger than that of the steel pipe pile 1 to form a lid. Next, after welding the small-diameter steel pipe of the required length and the flange 3 made of a steel plate to the required parts of the body by welding, scales and oil components on the inner and outer surfaces are removed by blasting, pickling or degreasing. . The outer surface is coated with polyolefin and the inner surface is coated with a thermosetting resin such as epoxy or polyester.

The polyolefin coating on the outer surface of the manhole body 10 of the present invention is preferably formed of a modified polyolefin powder coating through an epoxy primer coating from the viewpoint of workability. For the epoxy primer, the same epoxy used for coating the outer surface of the steel pipe pile 1 described above,
A mixture of a pigment and a curing agent is used.

As the modified polyolefin, a polyolefin composed of ethylene homopolymer or a copolymer of ethylene and α-olefin such as propylene, butene-1,4-methylpentene-1, hexene-1 and octene-1 is used. A modified polyolefin obtained by addition reaction of an acid anhydride such as maleic anhydride or itaconic anhydride is used.

The addition rate of maleic anhydride is from 0.05 to
Good adhesion is obtained in the range of 0.5% by weight. Like the polyolefin, the modified polyolefin also has the effect of reducing the sliding resistance with clay, silt and sand.

As a method for coating the epoxy primer and the modified polyolefin powder, for example, by spraying the epoxy primer on the outer surface of the steel material portion from which the scale and oil content on the inner and outer surfaces are removed by blasting, pickling or degreasing. , Then 140-250 ℃ in a heating furnace or burner
It is heated to a certain degree and electrostatically coated with modified polyolefin powder.

The thickness of the modified polyolefin coating is 0.5
When it is about 3 mm, good slidability with clay, silt and sand can be obtained, and scratches during construction can be reduced.

For coating the inner surface of the manhole body portion 10 of the present invention with a thermosetting resin such as epoxy or polyester, a general liquid epoxy paint or polyester paint for water and sewerage is used.

In order to give the manhole a clean feeling, these paints include carbon black (black), phthalocyanine green (green), isoindolinone yellow (yellow), quinacridone red (red), and perinone red (red). , General commercially available organic pigments such as phthalocyanine blue (blue), titanium oxide (white), chromium oxide (green), iron oxide (yellow, red), titanium yellow (yellow), cobalt oxide (blue, purple), etc. It is selected from general commercially available inorganic pigments at appropriate times and mixed to obtain a desired color.

In the case of a liquid thermosetting paint, the inner surface of the steel material portion from which the scale and oil have been removed from the inner and outer surfaces by blasting, pickling or degreasing is spray-coated and hardened to cover it. The coating thickness of the thermosetting paint is 0.3 to 1
If it is about mm, good corrosion resistance can be obtained.

The skirt portion at the bottom of the manhole body portion is inserted into the uncovered portion of the pile head of the steel pipe pile 1 and welded. After removing the welding spatter and oxide film on the surface of the welded joint with a belt sander or a wire brush,
The modified polyolefin powder is sprayed and a polyolefin coating is applied.

Around the upper part of the manhole body, concrete coping 6 is applied using a form, and a steel lid 7 is attached. The shape and size of the concrete coping 6 and the steel lid 7 should be a shape and size that are convenient for operations such as maintenance and inspection and cleaning of pipelines.

The structure of the present invention will be described with reference to FIG.

FIG. 1 is a drawing showing a side cross-section of a coated steel manhole installed on soft ground as an example of the present invention.

In the figure, 1 is a steel pipe pile that has been rust-treated by blasting or the like and has been subjected to ground treatment, and 2 is a steel pipe pile that constitutes the manhole body 1
Larger diameter steel pipe or square steel pipe, 3 is flange, 4
Is a polyolefin coating, 5 is a thermosetting resin coating, 6 is concrete coping, 7 is a steel lid, 8 is a soft ground layer, 9 is a ground support layer, 10 is a manhole body portion, 11
Indicates the skirt portion.

FIG. 2 compares the surface resistance of the coated steel pipe pile used in Example 1, which will be described later, by pushing through a packed bed of clay particles, silt particles or sand particles. It is drawing which shows the cross section of a test device, 12 is a coated steel pipe pile, 13 is a packing layer of clay particles, silt particles, or sand particles, 14 is a test device box, 15 is a load cell for measuring the punching load, Reference numeral 16 is a hydraulic cylinder for applying a vertical load, and 17 is a jig for supporting the box of the test apparatus.

Since the coated steel manhole of the present invention is itself supported by the ground support layer and has a small surface resistance against sliding of the soft ground and has excellent corrosion resistance, it is a soft ground. It is possible to suppress the destruction of the manhole during sliding and the pipeline connected to the manhole.

[0045]

The present invention will be described in detail with reference to the following examples.

As Example 1, the outer surface of a steel pipe (outer diameter 50 mm x length 500 mm x plate thickness 9 mm) was grit blasted to remove rust, and a chromate treatment agent (weight ratio of trivalent chromium to total chromium in aqueous solution). Was 0.4, the weight ratio of silica was 2.0, and the weight ratio of phosphoric acid was 1.0) was applied with a brush and dried. Chromate coating has a total chromium coverage of 450 m
It was g / m ² .

An epoxy primer (100 parts by weight of diglycidyl ether of bisphenol A, 3,9-bis (3-aminopropyl)) was applied to the outer surface of the chromate-treated steel pipe.
A mixture of 50 parts by weight of butyl glycidyl ether adduct of 2,4,8,10-tetraoxaspiro (5,5) undecane and 20 parts by weight of titanium oxide was applied with a brush and the steel pipe was heated to 200 ° C. by high frequency induction heating. And heated to form an epoxy primer coating. The thickness of the epoxy primer coating was 30 μm.

Immediately thereafter, the modified polyethylene and the polyolefin of Table 1 were extrusion-coated as a single layer in a double-layer round die to produce coated steel pipe piles 1 to 4. The modified polyolefin coating and the polyolefin coating each have a thickness of 150 μm.
m and 2.5 mm. Also, in the manufacture of coated steel pipe piles,
A coated steel pipe pile 5 in which the coating of polyolefin was omitted and the thickness of the modified polyethylene was 600 μm was also produced. For comparison, an uncoated steel pipe pile (steel pipe pile 6) without any of these coatings was also manufactured.

These coated steel pipe piles (1 to 5) and uncoated steel pipe piles (6) were made into clay particles (average particle diameter of 0.
018 mm), silt particles (average particle size 0.045 m
m) or sand particles (average particle diameter 0.35 diameter mm) in a packed bed (a portion of the pile length of 300 mm is loaded into the packed bed), and the load applied to the load cell when the pile is pushed out It was measured. At this time, the vertical load applied to the packed bed by the hydraulic cylinder 16 was 9.8 N / mm ² .

The measurement results of the punching load were converted into a value divided by the pile surface area and summarized in Table 1. From Table 1, the coated steel pipe piles 1 to 4 in which the polyolefin or the modified polyolefin of the present invention is coated on the outer surface of the steel pipe pile are compared with the uncoated steel pipe pile 5 in terms of clay particles, silt particles and Since the push-out load from the soft ground made of sand particles is remarkably small, the coated surface is good because the sliding resistance of the soft ground is small.

[0051]

[Table 1]

As Example 2, an outer diameter of 600 mm and a length of 1
A coating corresponding to the coated steel pipe pile (1) in Table 1 of Example 1 was applied using three steel pipes of 8 m × thickness of 19 mm. At this time, in order to connect the three piles with each other and the manhole body, the first steel pipe pile has a length of 10 m from the tip (a portion to be driven into the ground support layer) and a length of 250 mm from the rear end. The part (the part connected to the tip of the second) is uncoated,
The second steel pipe pile is uncovered at a portion having a length of 250 mm from both ends (the portion connected to the first rear end and the third tip), and the third steel pipe pile is a portion having a length of 250 mm from the tip ( 500mm from the part that connects with the second rear end) and the rear end
The part of the length (the part connected to the skirt part of the manhole body) was not covered.

A space required for the work was dug into the ground where the manhole was set up, and the first to third steel pipe piles were welded and connected to the ground support layer through the soft ground. On the way, the welded joint between the first and second steel pipe piles, and the second
A commercially available polyethylene heat-shrink sleeve was wrapped around the welded joint between the third steel pipe pile and the third steel pipe pile, and heat-sealed by burner heating to give a polyethylene coating.

When manufacturing the manhole body, the outer diameter is 15
A circularly cut steel plate (plate thickness 25 mm) is welded to the bottom of a steel pipe of 60 mm x length 2 m x plate thickness 12 mm, and an inner diameter 605 mm x length 250 mm x plate thickness is shown in the center of the bottom surface of the bottom plate as shown in FIG. A 19 mm steel pipe skirt 11 was welded. Next, at the height of 500 mm from the bottom plate of the body at two locations in the 180 ° direction of the steel pipe, the outer diameter is 300 mm and the length is 20 mm.
The flange was connected through a 0 mm steel pipe to manufacture the flange 3 shown in FIG.

The outer and inner surfaces of the manhole body thus manufactured were blasted to remove rust, heated to 200 ° C. and electrostatically coated with modified polyethylene powder to a film thickness of 1
mm outer surface coating 4 was applied. At this time, the skirt 11
Was uncoated by masking with tape. Then, the inner surface was coated with an epoxy paint by spray coating to form an inner surface coating 5 having a film thickness of 600 μm to manufacture a manhole body 10.

The manhole body 10 was inserted into the upper end of the cast coated steel pipe pile through the skirt portion 11, and the inserted portion was welded and connected. The welded portion was rubbed off with a belt sander to remove welding spatter, and then preheated to 120 ° C. with a burner, and the same epoxy primer as in Example 1 was brush-coated to a film thickness of 30 μm, and its surface was modified. Polyethylene powder with a film thickness of 1 mm
Was sprayed on and a polyolefin coating was applied.

At the top of the manhole, as shown in FIG.
A circular concrete coping 6 having an outer diameter of 2 m and a thickness of 300 mm was applied, a circular steel lid 7 having an outer diameter of 800 mm and a thickness of 8 mm was attached, and the manhole of the present invention was installed.

After the use for one year, the inside of the manhole was examined, and it was found that the inner coating film did not peel off and the corrosion resistance was sufficient.

[0059]

As described above, the coated steel manhole of the present invention is supported by the ground support layer by the steel pipe piles penetrating the soft ground, and the soft ground is formed on the outer surface above the ground support layer. The surface of the steel pipes and square steel pipes, which has a polyolefin coating with low surface resistance against sliding of the constituent soil and is highly corrosion-resistant, and which constitutes the manhole body installed above the steel pipe pile, is also coated with the polyolefin. Even if the ground vibrates due to an earthquake or the like, the sliding resistance with the soft ground made of clay particles, silt particles, and sand particles is reduced to reduce the sliding resistance. It is possible to provide a coated steel manhole with excellent durability, which exhibits excellent earthquake resistance such as reduction of thrust and also has improved corrosion resistance.

[Brief description of drawings]

FIG. 1 is a view showing a side cross section of a coated steel manhole installed on soft ground as an example of the present invention.

FIG. 2 is a drawing showing a cross section of a test device for comparing the surface sliding resistance of a coated steel pipe pile used in an example of the present invention.

[Explanation of symbols]

1 Steel pipe pile that has been subjected to ground treatment 2 Steel pipe or square steel pipe that constitutes the manhole body 3 Flange portion 4 Polyolefin coating 5 Thermosetting resin coating 6 Concrete coping 7 Steel lid 8 Soft ground layer 9 Ground support layer 10 Manhole body portion 11 Skirt portion 12 Coated steel pipe pile 13 Packed layer of clay particles, silt particles or sand particles for testing 14 Jig for box of test equipment 15 Load cell for measuring pushing load 16 Hydraulic cylinder for applying vertical load 17 Test equipment Jig to support the box

Claims (1)

[Claims] 1. A steel pipe pile (1) having a polyolefin coating (4) on the outer surface above the ground support layer of a steel pipe pile (1) which penetrates soft ground (8) and is driven into the ground support layer (9). A steel pipe or a square steel pipe (2) having a larger diameter is connected to the upper end of the pile (1), and a flange portion (3) is connected to the body of the steel pipe or the square steel pipe (2) with a steel pipe having a smaller diameter. The outer surface of the steel pipe or square steel pipe (2) and the flange portion is also coated with polyolefin (4), and the inner surface is coated with a thermosetting resin such as epoxy or polyester (5).
A coated man-made steel manhole, characterized in that a steel lid (7) is attached to the upper part of the steel structure subjected to the above with a concrete coping (6).