JP7728074B2 - Water guide member for drainage pipe and method for installing drainage pipe - Google Patents

Description

The present invention relates to a water conveyance section forming member for forming a water conveyance section placed inside a drainage pipe buried in the ground, and a drainage pipe construction method.

Drainage pipes are buried in ground with slopes or embankments, such as cut or embankment slopes, and extend to the slope or embankment to quickly drain soil water caused by rainfall. Holes are drilled into the drainage pipe's peripheral wall, allowing soil water to seep into the pipe and be discharged to the outside. When such drainage pipes are installed in locations where drainage frequency varies significantly depending on the season, they can easily become clogged with soil and sand, resulting in a deterioration of their drainage function. Pipe blockages can also occur due to plants and bacteria. To prevent such blockages, a filter element (water-conducting material) is placed inside the pipe body (tubular portion) of the drainage pipe (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2020-045632

To prevent soil and sand from flowing into the drainage pipe, it is desirable that there be no gap between the filter element and the pipe body. In other words, it is desirable that the diameter of the filter element is approximately the same as the inner diameter of the pipe body. However, if the diameter of the filter element is approximately the same as the inner diameter of the pipe body, the friction between the filter element and the inner surface of the pipe body increases when inserting the filter element into the pipe body, making it difficult to insert the filter element into the pipe body. In order to reduce the friction and make it easier to insert the filter element into the pipe body, filter elements with a diameter smaller than the inner diameter of the pipe body have actually been used.

In light of the above background, the present invention aims to provide a water guide section forming member for a drainage pipe that is easy to insert into the tubular section (pipe main body) and does not leave a gap between the inner surface of the tubular section and the outer surface of the filter member, as well as a drainage pipe installation method.

In order to solve the above problem, one aspect of the present invention is a water-conducting section-forming member (30, 43) for a drainage pipe (1, 41) buried in the ground, which comprises an expandable member (31) that extends in a predetermined direction, has an outer peripheral surface, and is expandable in a radial direction perpendicular to the predetermined direction, and a filter member (32) that extends in the predetermined direction, covers the outer peripheral surface of the expandable member, has voids through which water can pass, and is extensible in the circumferential direction.

According to this aspect, after inserting the water-conducting section-forming member into the tubular section, the outer diameter of the filter member can be increased by expanding the expandable member. Therefore, by inserting the water-conducting section-forming member into the tubular section while it has an outer diameter smaller than the inner diameter of the tubular section of the drainage pipe, the water-conducting section-forming member can be easily inserted into the tubular section. Furthermore, by expanding the expandable member after insertion, the gap between the inner surface of the tubular section and the outer surface of the filter member can be filled, preventing sediment from flowing into the drainage pipe.

The above aspect may further include a core material (44) extending in the predetermined direction and embedded within the expandable member (31).

In this embodiment, the core material makes it difficult for the water guide portion-forming member to bend, making it even easier to insert the water guide portion-forming member into the tubular portion.

In the above aspect, the expandable member (31) may include a polymer absorbent material that expands upon absorbing water.

In this embodiment, the expandable member expands with water, minimizing the impact on the environment around the construction site.

In the above aspect, the device may further include a membrane member (33) that is expandable in diameter and permeable to water, and that is disposed between the expandable member (31) and the filter member (32) so as to cover the outer peripheral surface of the expandable member (31) in the circumferential direction.

In this embodiment, when the expandable member expands, the membrane member prevents the expandable member from penetrating the voids in the filter member, thereby preventing a decrease in the water conductivity of the filter member.

In order to solve the above problem, one aspect of the present invention is a method for installing a drainage pipe (1, 41) in the ground using the water-conducting section-forming member of the above aspect, comprising the steps of placing a tubular section (2) having a hole (2a) in the ground, inserting the water-conducting section-forming member (30, 43) having an outer diameter smaller than the inner diameter of the tubular section (2) into the tubular section (2), and supplying water to the water-conducting section-forming member (30, 43) to expand the expandable member (31).

In this embodiment, the outer diameter of the water-conducting section-forming member is smaller than the inner diameter of the tubular section, making it easier to insert the water-conducting section-forming member into the tubular section. Furthermore, after the water-conducting section-forming member is inserted into the tubular section, the expandable member expands with water, filling the gap between the inner surface of the tubular section and the outer surface of the filter member. This prevents soil from entering the drainage pipe and reduces the impact of construction on the environment around the construction site.

The present invention provides a water guide section forming member for a drainage pipe and a drainage pipe installation method that can be easily inserted into a cylindrical section and does not leave a gap between the inner surface of the cylindrical section and the outer surface of the filter member.

1 is a side view showing a drain pipe and its components according to a first embodiment (A: elongated member, B: spiral member, C: drain pipe). 1A and 1B are diagrams illustrating a cross section perpendicular to the extension direction of the drainage pipe according to the first embodiment, and explaining the formation process of the drainage pipe (A: before expansion, B: during expansion, C: after expansion). 1A and 1B are diagrams showing a head protector for installing a drainage pipe according to the first embodiment (A: view from the front, B: view from the rear, C: cross-sectional view taken along the line CC in FIG. A); 1A and 1B are views showing a support pipe for installing a drainage pipe according to the first embodiment (FIG. 1A is a view from the front, and FIG. 1B is a front view). 1 is a diagram showing a procedure for installing a drainage pipe according to the first embodiment; 10A and 10B are diagrams illustrating a cross section perpendicular to the extension direction of the drainage pipe according to the second embodiment, and explaining the formation process of the drainage pipe (A: before expansion, B: during expansion, C: after expansion).

Embodiments of the present invention will now be described with reference to the drawings. Figure 1 shows a drainage pipe 1 and its constituent members according to the first embodiment. The drainage pipe 1 is buried in ground having a slope such as a slope, and drains water that has seeped into the ground. As shown in Figure 1(C), the drainage pipe 1 has a tubular portion 2 and a water-conducting portion 3 filled within the tubular portion 2. The tubular portion 2 has a plurality of elongated members 4 arranged parallel to one another, as shown in Figure 1(A), and a spiral member 5, as shown in Figure 1(B).

The long material 4 is a straight steel material that has been treated to be corrosion-resistant. Multiple long materials 4 are arranged parallel to one another and spaced apart on the circumference when viewed in the direction of their extension. For example, round steel bars with a diameter of approximately 3 mm may be used as the long materials 4, and 12 long materials 4 may be arranged on the circumference at equal intervals.

The helical member 5 is formed by winding a long piece of steel material in a spiral shape around an axis parallel to the extension direction of the long material 4, and is corrosion-resistant. Adjacent portions of the helical member 5 in the axial direction are spaced apart. The helical member 5 also has a circumferential shape with a predetermined diameter when viewed from the axial direction. For example, the helical member 5 may be formed by winding a rectangular long piece of steel material measuring 2 mm in length and 3 mm in width in a spiral shape at a pitch of 10.2 mm to have an outer diameter of 44 mm and an inner diameter of 38 mm.

As shown in Figure 1(C), the cylindrical portion 2 has a grid-like structure, and is formed by fixing the elongated material 4 to the outer periphery of the spiral member 5 by welding or other means. Because of the grid-like structure, the holes 2a formed in the cylindrical portion 2 are large and numerous. This increases the probability that the holes 2a in the cylindrical portion 2 will come into contact with the water passageway, making the holes 2a less likely to become clogged and improving drainage. Furthermore, because the elongated material 4 and spiral member 5 are made of steel, they are highly strong. Furthermore, because there are no restrictions on the angle that the cross section of the spiral member 5 forms with respect to the elongated material 4, the cylindrical portion 2 is relatively easy to manufacture.

As shown in Figure 2(C), the water conducting section 3 is a member having voids that allow water to pass through but prevent sediment and the like from passing through. The water conducting section 3 is formed by the radial expansion of the water conducting section-forming member 30 shown in Figure 2(A) along the drainage pipe 1. The water conducting section-forming member 30 includes an expandable member 31 that extends in the extension direction of the drainage pipe 1 and is expandable in the radial direction of the drainage pipe 1, and a filter member 32 that extends in the extension direction of the drainage pipe 1, covers the entire outer peripheral surface of the expandable member 31, has voids that allow water to pass through but prevent sediment from passing through, and is extensible in the circumferential direction of the drainage pipe 1. The outer diameter of the water conducting section-forming member 30 is smaller than the inner diameter of the tubular section 2. The water conducting section-forming member 30 may further include a membrane member 33 that is expandable in diameter and permeable to water, and is disposed between the expandable member 31 and the filter member 32 so as to cover the entire outer peripheral surface of the expandable member 31. The water guide section forming member 30 preferably has an extension length equal to the extension length of the tubular section 2, and the expandable member 31, filter member 32, and membrane member 33 preferably have the same extension length as one another.

The expandable member 31 contains a polymer absorbent material that expands upon absorbing water. For example, a material (such as polyacrylate) used as an absorbent body in absorbent articles such as diapers may be used as the polymer absorbent material. The expandable member 31 has a circular cross section perpendicular to its extension direction.

The filter element 32 contains a material that prevents the inflow of soil and sand while allowing rainwater that has infiltrated into the ground to pass through. For example, a plastic three-dimensional mesh molded product such as Hechimaron (registered trademark) manufactured by Shinko Nylon Co., Ltd. can be used as the filter element 32. The cross section of the filter element 32 perpendicular to its extension direction has a circular ring shape.

The membrane member 33 contains a material that is impermeable to the constituent materials of the filter member 32, such as a polymer absorbent, but is permeable to water. The membrane member 33 can expand in diameter by the elasticity of the membrane member 33 material itself, or by unfolding the pleated folded portion. For example, woven fabric or nonwoven fabric can be used as the membrane member 33. The membrane member 33 abuts against the inflatable member 31 and the filter member 32.

As shown in Figure 2(A), after inserting the water-conducting section-forming member 30 into the tubular section 2, water is supplied to the water-conducting section-forming member 30. As shown in Figures 2(B) and (C), the expandable member 31 expands radially due to the water (indicated by the arrow in Figure 2(B)), causing the membrane member 33 and filter member 32 to stretch circumferentially and expand in diameter. When the expandable member 31 expands until there is no gap between the outer surface of the filter member 32 and the inner surface of the tubular section 2, the water-conducting section-forming member 30 becomes the water-conducting section 3. The water may be supplied by workers or from underground water.

To insert the drainage pipe 1 into the ground, holes are drilled in the ground. If the ground remains self-supporting even after drilling, a hole of the required length is drilled and the drainage pipe 1 is inserted into the hole. An example of a drilling method for when the ground is not self-supporting is explained below. Figures 3 and 4 show the tools used for drilling, and Figure 5 shows the drilling procedure.

Figure 3 shows an annular head protector 9 having a bit 8 on its front surface, and Figure 4 shows a cylindrical support pipe 10 to which the head protector 9 is attached at its front end. The peripheral wall of the support pipe 10 is closed without any holes, and is open at the front and rear. The peripheral wall of the support pipe 10 has irregularities on its front end, with the protrusions 11 projecting into grooves 12 on the rear surface of the head protector 9. Because the protrusions 11 engage with the surface that defines the grooves 12, rotating the support pipe 10 in the circumferential direction also rotates the head protector 9. Furthermore, when the support pipe 10 is advanced, the head protector 9 also advances, but when the support pipe 10 is retracted, the protrusions 11 come out of the grooves 12, and the head protector 9 separates from the support pipe 10. The outer diameter of the support pipe 10 is smaller than the inner diameter of the tubular portion 2, and the outer diameter of the head protector 9 is larger than the outer diameter of the tubular portion 2. Therefore, when the support pipe 10 is placed inside the tubular portion 2 and the head protector 9 is attached to the front end of the support pipe 10, the tubular portion 2 is aligned with the head protector 9 in the front-to-rear direction.

Figure 5 (A) shows the initial state of the drilling cycle. The front end of the support pipe 10, to which the head protector 9 is attached, is inserted into the ground, and the support pipe 10 is positioned inside the tubular section 2.

The support pipe 10 is rotated circumferentially, and the bit 8 excavates the ground in a circular pattern while the head protector 9 and support pipe 10 are advanced approximately 300 to 500 mm (Figure 5(B)). At this time, the tubular portion 2 does not move, and soil and sand from the ground penetrates the front end of the support pipe 10. The tubular portion 2 is then advanced until its front end abuts the rear surface of the head protector 9 (Figure 5(C)). The soil and sand that has penetrated the front end of the support pipe 10 is then water-drilled using the rock drill 13 (Figure 5(D)). Because there are no holes in the circumferential wall of the support pipe 10, the water released from the rock drill 13 is not released outside the support pipe 10 and does not loosen the ground around the installation location of the drainage pipe 1. The slimy soil and sand are discharged, and the rock drill 13 is retracted (Figure 5(E)). The above cycle is repeated to drill the ground.

Once the hole has been drilled to the desired depth, the support pipe 10 is rotated slightly in the opposite circumferential direction and retracted. The head protector 9 then separates from the support pipe 10, leaving the head protector 9 and the tubular portion 2 in the hole. The head protector 9 is left in place in the hole.

As shown in Figure 2, a worker inserts the water-conducting section-forming member 30 into the tubular section 2 and supplies water to the water-conducting section-forming member 30 to expand the expandable member 31, thereby bringing the outer surface of the filter member 32 into contact with the inner surface of the tubular section 2. Water may be supplied from a hose (not shown) inserted into the gap between the tubular section 2 and the water-conducting section-forming member 30, or soil water passing through the hole 2a in the tubular section 2 may be used.

The effects of the first embodiment are explained below.

Because the outer diameter of the water guide section forming member 30 is smaller than the inner diameter of the tubular section 2, the water guide section forming member 30 can be easily inserted into the tubular section 2. Furthermore, in the completed state, the outer surface of the filter member 32 abuts against the inner surface of the tubular section 2, preventing sediment from flowing into the tubular section 2.

Because the membrane member 33 is located between the expandable member 31 and the filter member 32, when the expandable member 31 expands, the expandable member 31 is prevented from penetrating the voids in the filter member 32 and reducing the porosity of the filter member 32.

Because the expandable member 31 can be expanded by water, it can be expanded without polluting the surrounding environment at the construction site. Furthermore, even if the drainage pipe 1 is installed with the expandable member 31 insufficiently expanded, the expandable member 31 will expand due to rainwater that has entered the tubular portion 2, thereby sealing the gap between the inner surface of the tubular portion 2 and the outer surface of the filter member 32.

Next, a second embodiment of the present invention will be described with reference to Figure 6. In the description, components common to the first embodiment will be denoted by the same reference numerals and will not be described again.

The drainage pipe 41 according to the second embodiment comprises a tubular portion 2 and a water-conducting portion 42 filled within the tubular portion 2. The water-conducting portion 42 is a member having voids that allow water to pass through but not allow sediment and sand to pass through. The water-conducting portion 42 is formed by the radial expansion of the water-conducting portion-forming member 43 shown in FIG. 6(A) in the drainage pipe 41. The water-conducting portion-forming member 43 comprises an expandable member 31, a filter member 32, and a core material 44 embedded in the expandable member 31. The water-conducting portion-forming member 43 may further comprise a membrane member 33.

The core material 44 is less susceptible to bending deformation than the expandable member 31, filter member 32, and membrane member 33. The core material 44 is preferably positioned at the center of the expandable member 31 in the radial direction. The core material 44 preferably exists over the entire length of the water-conducting section-forming member 43 in the extension direction, but multiple core materials 44 may be arranged so that they are spaced apart from each other in the extension direction of the water-conducting section-forming member 43. For example, a steel or resin pipe or rod may be used as the core material 44.

The presence of the core material 44 makes it difficult for the water guide portion forming member 43 to bend, making it easier to insert the water guide portion forming member 43 into the tubular portion 2.

This concludes the explanation of specific embodiments, but the present invention is not limited to the above embodiments and can be widely modified and implemented. The tubular portion may be a steel or plastic pipe with holes in the circumferential wall. When installing a drainage pipe in a newly constructed embankment, the drainage pipe or tubular portion may be placed on the surface of the embankment while it is being constructed, rather than inserting the tubular portion after drilling the ground. The expandable member may contain a substance that expands by chemically reacting with a specified substance, instead of, or in addition to, a polymer absorbent material.

1, 41: Drainage pipe 2: Cylinder portion 3, 42: Water guide portion 30, 43: Water guide portion forming member 31: Expandable member 32: Filter member 33: Membrane member 44: Core material

Claims (3)

A water conveyance portion forming member for a drainage pipe buried in the ground,
an expandable member extending in a predetermined direction, having an outer circumferential surface, and including a polymer absorbent material that can absorb water and expand in a radial direction perpendicular to the predetermined direction;
a filter member that is a three-dimensional plastic net-like molded product that extends in the predetermined direction, covers the outer peripheral surface of the expandable member, has voids through which water can pass, and is extensible in the circumferential direction ;
a membrane member that is disposed between the outer peripheral surface of the expandable member and the filter member so as to cover the expandable member in the circumferential direction, the membrane member expanding in diameter as the expandable member expands, and the water-permeable membrane member;
A water guide portion forming member comprising: The water guide portion-forming member according to claim 1, further comprising a core material extending in the predetermined direction and embedded within the expandable member. A method for installing a drainage pipe in the ground using the water guide portion-forming member according to claim 1 or 2 ,
placing a cylindrical portion having a hole in the ground;
inserting the water guide portion forming member, which has an outer diameter smaller than an inner diameter of the cylindrical portion, into the cylindrical portion;
and supplying water to the water guide portion-forming member to expand the expandable member of the water guide portion-forming member.