JP7555291B2 - Steel pipe wall and dam structure - Google Patents

Description

The present invention relates to a steel pipe wall and a dam structure.

Impermeable sabo dams are known to be installed in mountain streams and other areas to prevent landslides. Between the sleeves of an impermeable sabo dam, a water passage is formed (see, for example, Patent Document 1).

JP 2017-101507 A

For example, an impermeable sabo dam blocks sediment (unstable sediment) that is washed down from the upstream side by water volume caused by normal rainfall. When the upstream side of an existing impermeable sabo dam becomes filled with sand, dredging work is carried out. Incidentally, the amount of unstable sediment that has accumulated on the upstream side of a river decreases over time, and the role of the sabo dam changes as the amount of unstable sediment decreases.

For example, a decrease in unstable sediment may result in a situation where rocks, driftwood, etc. on the upstream side of a river are easily washed away even by normal rainfall. In this case, the objects that the sabo dam blocks change from unstable sediment to rocks, driftwood, etc. A permeable sabo dam with a permeable section is desirable as a dam for blocking rocks, driftwood, etc.

For example, when changing the structure of the impermeable sabo dam 200 shown in FIG. 6A to the permeable sabo dam 300 shown in FIG. 6B, it is necessary to remove the water-passing section 210 of the concrete sabo dam, build a new permeable section 310, and then install a new capture body 320. In such a case, it is expected that the work of changing the impermeable sabo dam 200 to the permeable sabo dam 300 will be very laborious and will take a long time to complete.

In this way, there is a demand to change from impermeable sabo dams to permeable sabo dams in mountainous areas to deal with the runoff of soil, rocks, driftwood, etc. in response to secular changes (decrease) in the amount of soil runoff in response to a certain level of rainfall.

Therefore, the present invention was made in consideration of the above problems, and aims to provide a technology that can easily change the structure of a sabo dam from an impermeable type to a permeable type.

In order to solve the above problems, the steel pipe wall of the present invention is characterized in that it comprises a plurality of steel pipes connected to each other, one end of which in the longitudinal direction is buried in the ground, and is provided on the upstream side of a dam having a pair of sleeves extending from both sides of a river at a predetermined distance from each other and a permeable portion provided between the pair of sleeves, covers the permeable portion in the flow direction of the river, and is used to block objects that attempt to pass through the permeable portion.

The steel pipe wall according to one embodiment of the present invention comprises a front portion in which a plurality of steel pipes are connected in a straight line and faces the flow direction of the river, and a side portion located between the pair of sleeve portions and the front portion, which is formed by steel pipes connected at both ends of the front portion in the connection direction of the steel pipes in a direction intersecting the connection direction.

In one embodiment of the steel pipe wall of the present invention, the steel pipes have joints extending along the longitudinal direction, and the steel pipes are connected to each other via the joints.

The steel pipe wall body according to one embodiment of the present invention is constructed on the upstream side of an extension section constructed along the upstream wall section facing the upstream side of each pair of sleeve sections.

Furthermore, in order to solve the above problem, the dam structure according to the present invention comprises a dam having an upstream wall facing the upstream side and a downstream wall facing the downstream side, extending from both banks of a river, a pair of sleeves spaced apart by a predetermined distance from each other, and a permeable section provided in the pair of sleeves, and a steel pipe wall body provided on the upstream side of the permeable section of the dam and covering the permeable section, the steel pipe wall body being formed from a plurality of steel pipes with one end of the steel pipes buried in the ground in the longitudinal direction, and being used to block objects attempting to pass through the permeable section.

The dam structure according to one aspect of the present invention further includes an extension that fills the gap between the upstream wall of the pair of sleeves and the steel pipe wall.

According to the present invention, the structure of the dam can be changed from an impermeable type to a permeable type.

FIG. 1 is a perspective view showing a sabo dam structure according to an embodiment of the present invention. This is a schematic plan view of a sabo dam structure viewed from above in the height direction, and the capture body is not shown. FIG. 2 is a schematic front view of the sabo dam structure viewed from the upstream side in the flow direction. This is a schematic diagram of the sabo dam structure viewed in the width direction at the transmission section. FIG. 2 is a diagram showing a joint portion for connecting steel pipes together. 13A to 13C are diagrams showing the process of constructing an extension portion on an existing sabo dam. FIG. 2 is a diagram showing a process for constructing a steel pipe wall body. FIG. 13 is a diagram showing a modified example of a sabo dam structure having a steel pipe wall body. FIG. 1 is a perspective view showing a conventional impermeable sabo dam. FIG. 1 is a perspective view showing a conventional permeable sabo dam.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
<Configuration of erosion control dam structure>
FIG. 1 is a perspective view showing a dam structure (hereinafter also referred to as an "erosion-control dam structure") 1 according to this embodiment. The erosion-control dam structure 1 according to this embodiment is installed in a mountain stream or the like to block objects such as soil and sand, rocks, and driftwood flowing from upstream. The erosion-control dam structure 1 includes a dam (hereinafter also referred to as an "erosion-control dam") 10 constructed by a concrete construction method, an extension portion 30, and a steel pipe wall body 50 formed by a plurality of steel pipes 51. The erosion-control dam structure 1 may be constructed by a soil cement construction method. For convenience of explanation, the width direction of the river is designated as "W", the flow direction as "F", and the height direction of the erosion-control dam 10 as "H".

The sabo dam structure 1 according to this embodiment comprises an sabo dam 10 having an upstream wall 111 facing the upstream side and a downstream wall 112 facing the downstream side, a pair of sleeves (non-overflow sections) 11 spaced apart from each other by a predetermined distance, and a permeable section 12 provided in the pair of sleeves 11, extending from both banks of the river, and a steel pipe wall body 50 provided upstream of the permeable section 12 of the sabo dam 10 and covering the permeable section 12 in the flow direction, one end of the steel pipe wall body 50 being buried in the ground in the longitudinal direction, having a plurality of steel pipes 51 connected to each other, and serving to dam up objects attempting to pass through the permeable section 12. The configuration of the sabo dam structure 1 will be described in detail below.

The sabo dam 10 has a pair of non-overflow sections 11, a permeable section 12, and a capture body 13. The pair of non-overflow sections 11 extend close to each other in the width direction W from both banks of the river. The pair of non-overflow sections 11 are spaced a predetermined distance from each other in the width direction W of the river so that the permeable section 12 is formed. The capture body 13 is installed in the permeable section 12.

The pair of non-overflow sections 11 prevent debris flow and other flows flowing from the upstream side of the river from overflowing downstream beyond the sabo dam structure 1. The non-overflow sections 11 have an upstream wall section 111, a downstream wall section 112, a side wall section 113, and a top end section 114.

The upstream wall 111 faces the upstream side of the river, is a wall that absorbs the impact of flowing water, debris flow, etc. from upstream, and is adjacent to the river bank. The upstream wall 111 is constructed so that it slopes downward toward the upstream side from the upper end to the lower end. The downstream wall 112 faces the downstream side of the river, is positioned at a specified distance from the upstream wall 111, and is adjacent to the river bank. The downstream wall 112 is constructed so that it slopes downward toward the downstream side from the upper end to the lower end.

The side wall 113 faces the permeable section 12 and extends between the upstream wall 111 and the downstream wall 112 in the river flow direction F. The side wall 113 is constructed so as to stand upright on the top surface of the foundation concrete 121 of the permeable section 12, which will be described later.

The top end 114 is a wall portion that faces upward in the height direction H. The top end 114 is inclined in the width direction W from the river bank toward the transparent section 12. The end of the top end 114 on the transparent section 12 side in the width direction W forms a sleeve side surface 115 that has a larger angle of inclination than the other portions.

The permeable section 12 is provided between a pair of non-overflow sections 11 and allows flowing water to pass through. The permeable section 12 has a concrete foundation 121 provided on the riverbed and is formed one step higher than the riverbed.

The capture body 13 is installed on the foundation concrete 121 of the permeable section 12, and is formed by assembling steel pipes or steel or concrete columns in a lattice pattern. The capture body 13 allows flowing water and small soil and sand from the river to pass through, and captures large rocks and driftwood when a debris flow occurs.

The extension portion 30 is provided on the upstream wall portion 111 side in each non-overflow portion 11 and extends upstream from the upstream wall portion 111. The mutually facing surfaces of the extension portions 30 in each non-overflow portion 11 are flush with the side wall portion 113 in the flow direction F (see FIG. 2A). The extension portion 30 may be constructed by a soil cement construction method.

The extension 30 is provided between the sabo dam 10 and the steel pipe wall body 50 described below, and is constructed by a concrete construction method. Figure 2A is a schematic plan view of the sabo dam structure 1 as seen from above in the height direction H, and the capture body 13 is not shown. Figure 2B is a schematic front view of the sabo dam structure 1 as seen from the upstream side in the flow direction F. Figure 2C is a schematic view of the sabo dam structure 1 as seen in the width direction W at the permeable portion 12.

The upstream wall portion 111 has a slope that slopes from top to bottom toward the upstream side in the height direction H. The steel pipe wall body 50 described below extends in the vertical direction, and a gap S, for example, of a roughly triangular shape, is generated between the upstream wall portion 111 and the steel pipe wall body 50. The extension portion 30 serves to close the gap S.

The extension portion 30 is formed on the downstream side along the slope of the upstream wall portion 111 of the non-overflow portion 11 and is inclined. In contrast, the surface of the extension portion 30 facing the upstream side is formed to extend vertically.

The top surface 31 of the extension portion 30 is at approximately the same height as the transparent portion 12 and the capture body 13 in the height direction H. The extension portion 30 extends 3.0 m to 5.0 m in the width direction W. The extension amount 30w of the extension portion 30 in the width direction W is equal to or greater than the width 114f of the top end portion 114 in the flow direction F or the width 115w of the sleeve side surface 115 in the width direction W (30w≦114f; 115w). In addition, the surface of the extension portion 30 facing upstream in the flow direction F is flush with the foundation concrete 121 of the transparent portion 12 (see Figures 2A and 2C).

The extension amount 30w is preferably equal to or greater than the larger of the width 114f of the top end and the width 115w of the sleeve side surface 115. When the height of the sleeve side surface 115 in the vertical direction is taken as the sleeve height 115h, the sleeve height 115h is set based on the expected flow rate. For example, when the expected flow rate is relatively large, the sleeve height 115h is high and the extension amount 30w is equal to or greater than the width 115w, and when the expected flow rate is relatively small, the sleeve side surface 115h is low and the extension amount 30w is equal to or greater than the width 114f.

The steel pipe wall body 50 comprises a plurality of steel pipes 51 connected to each other, one end of which is buried underground in the longitudinal direction, has an upstream wall portion 111 facing the upstream side of the river and a downstream wall portion 112 facing the downstream side, and is provided upstream of a sabo dam 10 having a pair of non-overflow portions 11 extending from both banks of the river at a predetermined distance from each other and a permeable portion 12 provided between the pair of non-overflow portions 11, and is used to cover the permeable portions 12 and hold back sediment that attempts to pass through. The configuration of the steel pipe wall body 50 will be described in detail below.

The steel pipe wall 50 is a so-called steel pipe sheet pile formed by connecting multiple cylindrical steel pipes 51 together. Each steel pipe 51 is erected on the riverbed with its longitudinal direction along an axis x passing through the center and each axis x extending vertically.

In the sabo dam structure 1 according to this embodiment, the steel pipe wall body 50 is installed immediately upstream of the foundation concrete 121 and the extension part 30 of the permeable part 12 in the flow direction F. It is desirable that the distance between the sabo dam 10 and the steel pipe wall body 50 in the flow direction F is as close as possible, and the steel pipe wall body 50 is installed as close to the sabo dam 10 as is permissible in terms of design and construction work. As a result, the sabo dam structure 1 can, for example, have the steel pipe wall body 50 block the soil flowing from the upstream side in the flow direction F in front of it, and the extension part 30 block the soil flowing into the permeable part 12 from the side. It is preferable that the steel pipe wall body 50 is installed within a range of, for example, a maximum of 100 cm, particularly 50 cm, upstream from the foundation concrete 121 or the extension part 30.

The steel pipe wall body 50 extends from the riverbed in the height direction H to the same or approximately the same height as the lower end of the sleeve side surface 115 of the non-overflow section 11. The tip of the steel pipe wall body 50 is located lower than the top end portion 114 of the non-overflow section 11 when viewed in the flow direction F. When the sabo dam structure 1 is viewed from the upstream side (see Figure 2B), the permeable section 12 is covered and hidden by the steel pipe wall body 50. The tip of the steel pipe wall body 50 extends to a position equivalent to the position of the top end of the water-passing section 210 (see Figure 6A) in an impermeable sabo dam.

Figure 3 shows joints 52, 53 that connect steel pipes 51 together. Each steel pipe 51 is connected to another via joints 52, 53. The joints 52, 53 are provided on the outer circumferential surface of the steel pipe 51 along the axis x. The joints 52, 53 are provided at positions that face each other in the radial direction.

The joint part 52 is a female joint part whose cross-sectional shape intersecting the axis x is approximately C-shaped. The joint part 52 has a stud part 52a and a socket part 52b. The stud part 52a is erected on the outer circumferential surface of the steel pipe 51, and the socket part 52b is formed approximately C-shaped in a plan view. The socket part 52b is integrally formed on the end part of the stud part 52a opposite the part connected to the steel pipe 51.

The joint part 53 is a male joint part whose cross section intersecting the axis x is approximately I-shaped. The joint part 53 has a stud part 53a and a stem part 53b. The stud part 53a is erected on the outer circumferential surface of the steel pipe 51 at a position radially opposite the stud part 52a of the joint part 52. The stem part 53b is formed in a roughly elliptical shape in a plan view, and is formed integrally with the end part of the stud part 53a on the opposite side to the part connected to the steel pipe 51.

When the stem portion 53b of the joint portion 53 is surrounded by the socket portion 52b, the joint portions 52 and 53 are engaged or engageable with each other. The joint portions 52 and 53 are engaged (fitted) by relatively inserting the stud portion 3a of the joint portion 53 into the inner space of the socket portion 52b of the joint portion 52. In other words, the two adjacent steel pipes 51 are engaged with each other by sliding the stem portion 53b of the joint portion 53 of one steel pipe 51 along the axis x or the longitudinal direction into the socket portion 52b of the joint portion 52 of the other steel pipe 51. By connecting the two steel pipes 51 to each other via the joint portions 52 and 53, the gap formed between the steel pipes 51 can be at least partially blocked along the axis x or the longitudinal direction. The joint portions 52 and 53 can be made using known techniques and are not particularly limited.

The steel pipe wall body 50 has one end in the axis x or longitudinal direction cast directly into the riverbed. The steel pipe wall body 50 is provided so that at least both ends of the steel pipe wall body 50 in the width direction W overlap with the extension portion 30. The tip of the steel pipe wall body 50 is at least at the same height as the capture body 13 and the extension portion 30 in the height direction H.

<Method of constructing a sabo dam structure>
Fig. 4A is a diagram showing a process for constructing an extension portion 30 in an existing erosion-control dam 10. Fig. 4B is a diagram showing a process for constructing a steel pipe wall body 50. When an existing erosion-control dam 10 is converted into the erosion-control dam structural body 1 according to this embodiment, an extension portion 30 is constructed for each non-overflow portion 11 on the upstream side of the erosion-control dam 10.

Then, the steel pipe 51 is driven into the riverbed immediately upstream of the foundation concrete 121 and the extension 30. Next, another steel pipe 51 is driven into the riverbed while engaging its joint 53; 52 with the joint 52; 53 of the first steel pipe 51 driven into the riverbed. This operation is repeated a predetermined number of times along the width direction W to form a steel pipe wall body (steel pipe sheet pile) 50 of the required length in the width direction W. This completes the construction of the sabo dam structure 1.

At the beginning of a disaster, the erosion control dam structure 1 mainly functions to hold back sediment. For example, when a large amount of sediment flows in with heavy rain, the sediment is held back by the steel pipe wall body 50, and the sediment accumulates upstream of the erosion control dam structure 1.

As time passes, the amount of sediment flowing from upstream tends to decrease. As the amount of runoff sediment decreases, the role of the sabo dam structure 1 also changes. In other words, it is necessary to change the function of the sabo dam from an impermeable type, which is to prevent sediment from flowing downstream, to a permeable type, which is to block rocks, driftwood, and other debris that are washed away when a debris flow occurs.

The extension portion 30 may be constructed after the steel pipe wall body 50 is installed. By installing the steel pipe wall body 50 first, the extension portion 30 can be constructed so as to fill the gap formed between the steel pipe wall body 50 and the erosion control dam 10. This makes it possible to keep the gap between the steel pipe wall body 50 and the erosion control dam 10 small.

With the above-described erosion-control dam structure 1, the steel pipe 51 can be easily pulled out of the riverbed after dredging the accumulated sediment. The steel pipe wall body 50 can be easily removed, and the impermeable erosion-control dam structure 1 can be quickly changed to a permeable erosion-control dam (see, for example, Figure 4A).

Furthermore, since the steel pipes 51 in the steel pipe wall body 50 are connected to each other only via their respective joints 52, 53, the connection between the steel pipes 51 can be easily released. In addition, the joints 52, 53 also seal the gaps between the steel pipes 51 along the axis x or longitudinal direction of the steel pipes 51.

Furthermore, an extension 30 is provided between the sabo dam 10 and the steel pipe wall body 50. The extension 30 is formed along the slope of the upstream wall 111 on the downstream side, and is formed to extend vertically on the upstream side. This makes it possible to keep the gap formed between the steel pipe wall body 50 and the extension 30 small.

＜Other＞
Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and includes all aspects included in the concept of the present invention and the scope of the claims. In addition, each configuration may be appropriately and selectively combined so as to achieve at least a part of the above-mentioned problems and effects. In addition, for example, the shape, material, arrangement, size, etc. of each component in the above embodiment may be appropriately changed depending on the specific use mode of the present invention. For example, although the steel pipe wall body 50 in the above embodiment is formed in a straight line in a plan view, it may be formed in an approximately U-shape in a plan view.

Figure 5 shows a modified example of a sabo dam structure 1A having a steel pipe wall body 50A. The steel pipe wall body 50A has a front portion 60A and a side portion 70A. The front portion 60A is a portion in which multiple steel pipes 51 are connected in a straight line and face the flow direction F of the river. The side portion 70A is a portion formed by steel pipes 51 connected in a direction (flow direction F) that intersects the connection direction (width direction W) at both ends of the front portion 60A in the connection direction (width direction W) of the steel pipes 51. The side portion 70A is located between a pair of non-overflow portions 11 or extension portions 30 and the front portion 60A.

In addition, in the above embodiment, the extension 30 is additionally installed on the existing erosion control dam 10, but it may also be constructed integrally with the newly constructed erosion control dam 10.

The space surrounded by the upstream wall 111, downstream wall 112, side wall 113, and top end 114 may be filled with soil cement, which is produced by stirring and mixing the on-site soil generated when laying the foundation concrete 121 with cement and cement milk. When the filler solidifies, its weight will absorb the impact of the debris flow.

The upstream wall 111 is constructed by connecting multiple rectangular steel panels with corrugated cross sections, and the steel panels are connected to each other with bolts and nuts, and the joints may be waterproofed by applying sealing tape or the like.

The downstream wall 112 is constructed by connecting multiple rectangular steel panels with corrugated cross sections. The steel panels are connected to each other with bolts and nuts, and the joints may be waterproofed by applying sealing tape or the like.

The side wall 113 is constructed by connecting multiple rectangular steel panels with corrugated cross sections, and the steel panels are connected to each other with bolts and nuts. The joints may be waterproofed by applying sealing tape or the like.

1, 1A: Sand-control dam structure (dam structure), 10: Sand-control dam (dam), 11: Non-overflow portion (sleeve portion), 12: Permeable portion, 13: Capture body, 30: Extension portion, 30w: Extension amount, 31: Top end surface, 50, 50A: Steel pipe wall body (steel pipe sheet pile), 51: Steel pipe, 52, 53: Joint portion, 60A: Front portion, 70A: Side portion, 111: Upstream wall portion, 112: Downstream wall portion, 113: Side wall portion, 114: Top end portion, 114f: Width, 115: Sleeve side, 115w: Width, 115h: Sleeve height, 121: Foundation concrete, 200: Impermeable sand-control dam, 210: Water passage portion, 300: Permeable sand-control dam, 310: Permeable portion, 320: Capture body

Claims (6)

The present invention provides a method for constructing a steel pipe structure comprising the steps of:
A steel pipe wall body, which is provided on the upstream side of a dam having a pair of sleeves extending from both banks of a river at a predetermined distance from each other and a permeable portion provided between the pair of sleeves, covers the permeable portion in the flow direction of the river, and is used to block objects attempting to pass through the permeable portion. A front portion in which the plurality of steel pipes are connected in a straight line and faces the flow direction of the river;
A side portion formed by steel pipes connected in a direction intersecting the connection direction at both ends of the front portion in the connection direction of the steel pipes, and located between the pair of sleeve portions and the front portion;
The steel pipe wall body according to claim 1, further comprising: The steel pipe wall body according to claim 1 or 2, characterized in that the steel pipe has a joint portion extending along the longitudinal direction of the steel pipe , and the steel pipes are connected to each other via the joint portion. A steel pipe wall body according to any one of claims 1 to 3, characterized in that it is constructed on the upstream side of an extension constructed along the upstream wall portion facing the upstream side of each pair of sleeve portions. a dam having an upstream wall facing the upstream side and a downstream wall facing the downstream side, the dam having a pair of sleeves extending from both sides of a river at a predetermined interval from each other, and permeable portions provided in the pair of sleeves;
A steel pipe wall body provided upstream of the permeable portion of the dam to cover the permeable portion;
Equipped with
The steel pipe wall body has one end in the longitudinal direction buried in the ground, has a plurality of cylindrical steel pipes connected to each other, and is used to block objects attempting to pass through the permeable section. The dam structure according to claim 5, further comprising an extension that fills the gap between the upstream wall of the pair of sleeves and the steel pipe wall.

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