Culvert construction equipment

Abstract

To provide a culvert construction device capable of constructing culvert drainage with a tractor used by a farmer.SOLUTION: A culvert construction device comprises: a vertical cut blade 21; a curved cut blade 22; an inner side soil lifting member 35 and an outer side soil lifting member 36 placed inside and outside of the vertical cut blade 21, respectively, on a lower end of the vertical cut blade 21 and having an upward slope in a rear direction in a rectangular form in a plan view; and a material installing unit 40 placed in a rear direction of the vertical cut blade 21 and supplying culvert pipes T and hydrophobic material F. The culvert pipes T and the hydrophobic material F are supplied with the material installing unit 40 after the soil is cut with the vertical cut blade 21 and the curved cut blade 22 through advancing, and the inner side soil lifting member 35 and the outer side soil lifting member 36 lift the soil above the same to be expanded and softened.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an underdrain construction device for constructing underdrainage that can drastically improve drainage in farmland that has drainage defects that hinder agricultural productivity and where appropriate drainage improvement work cannot be carried out due to gravel or dense soil layers in the soil. [Background technology]

[0002] In order to promote the production of field crops, there is a need to promote the cultivation of a variety of field crops and develop high-value-added agriculture by utilizing paddy fields as upland.To achieve this, it is necessary to enhance drainage improvement technology to improve the drainage function of farmland, which determines the productivity of field crops.To develop underdrainage, a core technology, there is a need to develop underdrainage construction technology that can be easily and inexpensively installed using farm equipment such as tractors owned by farmers, even in farmland with a lot of gravel around rivers in Japan's alluvial rice paddy areas, and in farmland with stones and dense soil layers in mountainous areas.

[0003] Conventional underdrainage construction methods include those often installed as part of land improvement projects. Generally, construction procedures, standard methods, and standards are outlined in the Land Improvement Project Design Standards Plan "Underdrainage" (established in May 2017), supervised by the Ministry of Agriculture, Forestry and Fisheries, and construction methods are based on these. Underdrainage constructed using these methods on farmland with poor drainage is constructed by burying an underdrain pipe made of synthetic resin or other material with many holes at a depth of about 60cm to 90cm, and then installing trench-like structures with highly permeable material buried on top of that as a hydrophobic material at regular intervals of about 5 to 10m.

[0004] Proposed underdrain pipe burying devices for these conventional construction methods include a rotating chain trencher (Patent Document 1) that constructs a pipe lead-in trench and a plow-type drain layer (Patent Document 2). Trenchers are specialized machines that are complex, large, and expensive. They are manufactured and owned by civil engineering companies and are not commercially available. Large models of drain layer construction machines are available for bulldozers, but they are shallow, burying depths of approximately 60 cm. In addition, preliminary soil excavation work is required before construction, which is time-consuming. A small model for tractors has also been proposed (Non-Patent Document 1), but despite the need to dig a 40 cm deep trench and break up the subsoil to a depth of 50 cm in advance, the pipe is buried shallowly, at only 50 cm. These issues, along with the inability to construct such devices on agricultural land with gravel, make them unsuitable for use on agricultural land with gravel. Even the underdrain pipe burying device (Patent Document 3), which solves these issues, was not applicable to agricultural land with gravel.

[0005] Furthermore, the equipment for burying materials and burying underdrain pipes (Patent Document 3) cannot handle large stones and gravel, and the machine is large and it is not possible to sufficiently balance the left and right of the machine.A subsoil breaker (Patent Document 4) is an equipment that can handle stones and gravel, but there is a limit to how much depth can be adjusted, and when a mechanism for burying underdrain pipes or hydrophobic material is attached to the rear of the equipment, it is not possible to sufficiently balance the left and right of the machine.

[0006] For these reasons, other than using construction machinery such as backhoe excavators, there is no simple, low-cost construction technique that allows a variety of implementing entities to construct culverts deep enough to provide sufficient drainage function, even on agricultural land with gravel and dense soil layers. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2012-41815 A (Trencher-type underdrain burying device) [Patent Document 2] JP 2004-3268 A (Drain layer type underdrain installation device) [Patent Document 3] JP 2016-0522660 A (Patent No. 6187874) (Hydrophobic material and underground pipe installation device) [Patent Document 4] JP 2020-184891 A (subsoil crusher) [Non-patent literature]

[0008] [Non-Patent Document 1] "Shallow Underdrain Construction Device for Tractor Use" Revised Edition, NARO Tohoku Agricultural Research Center, March 30, 2019 Summary of the Invention [Problem to be solved by the invention]

[0009] The above-mentioned conventional techniques have the following problems. (1) Construction methods using excavators such as trenchers and hydraulic shovels require expensive specialized machinery, which means the cost of the machinery is extremely high and only a limited number of people can use it. Furthermore, trenchers cannot be used in conditions where gravel is present, and only hydraulic shovels can be used. (2) The towed drain layer method is difficult to control the burial depth because the burial depth is shallow even when constructed using large machinery, and the resistance of the machinery is caused by the hardness of the soil. In addition, it cannot be used in conditions where gravel is present. (3) When construction is carried out using large machinery, if the weather is bad, the road will become muddy as it moves, which will actually exacerbate poor drainage. (4) In the case of small towable drain layer systems for tractors, the buried depth of the underdrain pipe is extremely shallow, at a maximum of 40 to 50 cm. In addition, they cannot be used in conditions where gravel is present. (5) Furthermore, the conventional technology does not have a mechanism for adjusting the left and right balance of the device due to the resistance applied to the device parts where the underdrain pipes and hydrophobic material are buried.

[0010] In view of the above-mentioned current situation, the present invention aims to provide an underdrain construction device that allows farmers to easily construct underdrainage structures that have previously been constructed by construction machinery, even on farmland with gravel or dense soil layers, using only the pulling force of a tractor or the like, in order to improve poorly drained farmland into highly productive farmland. [Means for solving the problem]

[0011] In order to achieve the above object, the present invention provides the following configuration: Note that the numbers in parentheses are symbols in the drawings to be described later, and are provided for reference. Aspects of the present invention are driven by ahead An underdrain construction device that constructs underdrain drainage in soil by advancing, a vertical cutting blade (21) having a vertical plate portion (21b) extending in the vertical direction and a blade provided along the front edge of the vertical plate portion (21b); In the left-right direction perpendicular to the front-rear direction of the underdrain construction device The vertical plate portion (21b) of the vertical cutting blade (21) At a specified interval a bent cutting blade (22) including a bent plate portion including an upper vertical plate portion (22b) extending in a vertical direction parallel to the vertical cutting blade (21) and a lower inclined plate portion (22c) extending obliquely downward from the lower end of the upper vertical plate portion (22b) so as to approach the vertical cutting blade (21), and a blade provided along the front edge of the bent plate portion; At the lower end of the vertical cutting blade (21), The surface facing the bent cutting blade (22) in the left-right direction an inner soil lifting member (35) disposed on the inside, including an inner front blade (31) facing forward and an inner soil lifting plate (32) continuing to the rear of the inner front blade (31), and having a rectangular shape in a plan view with an upward slope toward the rear; At the lower end of the vertical cutting blade (21), The surface opposite to the surface facing the bent cutting blade (22) in the left-right direction an outer soil lifting member (36) disposed on the outside, including an outer front blade (33) facing forward and an outer soil lifting plate (34) continuing to the rear thereof, and having a rectangular shape in a plan view and an upward slope toward the rear; a material burying unit (40) disposed behind the vertical cutting blade (21) and supplying an underdrain pipe (T) and a hydrophobic material (F); As the machine advances, the soil is cut by the vertical cutting blades (21) and the curved cutting blades (22), and the soil above is lifted by the inner soil lifting members (35) and the outer soil lifting members (36), crushed, softened, and then an underdrain pipe (T) and a hydrophobic material (F) are supplied by the material burying unit (40). - In the above aspect, the length in the front-rear direction and / or the width in the left-right direction of each of the inner soil lifting member (35) and the outer soil lifting member (36) are set so that the rightward pressure (pr) and the leftward pressure (pl) that the vertical cutting blade (21) receives from the soil are approximately the same. In the above aspect, the inner soil lifting member (35) is selected from a plurality of inner soil lifting members (35) having different lengths in the front-to-rear direction and is attached in an exchangeable manner. - In the above aspect, the outer soil lifting member (36) is selected from a plurality of outer soil lifting members (36) having different front-to-rear lengths and / or different left-to-right widths and is attached interchangeably. - In the above aspect, the present invention is characterized in that it has a means for adjusting the fixed positions of the vertical cutting blade (21) and the curved cutting blade (22) in the vertical direction in order to adjust the construction depth of the underdrain drainage. In the above aspect, the upper ends of the vertical cutting blade (21) and the curved cutting blade (22) are fixed to a rotating shaft (24), and the rotating shaft (24) is fixed so as not to rotate until a torque equal to or greater than a certain level is applied, and becomes rotatable when a torque equal to or greater than the certain level is applied. [Effects of the Invention]

[0012] According to the present invention, the following effects are achieved compared to conventional underdrain pipe burying devices, and therefore the structure required for underdrain drainage can be reliably constructed. (I) The cutting blade unit, which has a vertical cutting blade and a curved cutting blade, cuts the soil, while the soil lifting unit, which has inner and outer soil lifting members located on both the left and right sides of the vertical cutting blade, lifts the soil, widely crushing and softening the soil. This allows the subsurface construction part of the underdrain pipe installation device to be inserted reliably to the specified depth. It also allows for the construction of underdrain drainage with a high degree of freedom at the specified depth and at any interval. Furthermore, the softened soil around the underdrainage can be expected to have a greater effect on drainage. (II) The soil softening effect, the left-right balance adjustment effect of the soil lifting unit, and the soil insertion force strengthening effect make it easier to bury materials. The underground construction part of the underdrain pipe burying device is inserted vertically into the soil, allowing for a stable construction depth for underdrain drainage to be maintained. (III) Due to the soil swelling and softening effect and the shape of the cutting blade unit, stones up to about 30 cm in diameter can pass through the underdrain construction device even when up to 10% of the soil is made up of stones. If stones larger than this are present, the safety device of the underdrain construction device will function and construction will be suspended, preventing damage to the underdrain construction device. (IV) Since no excavation of soil is required for construction of underdrainage, even if the subsoil contains chemically unsuitable soil, underdrainage can be constructed without worsening the chemical properties of the farmland.

[0013] As a result of the above effects, in farmland with poor conditions such as the presence of gravel in the soil, it has become possible to create underdrainage systems that can be easily towed by a farmer using a tractor or other equipment, replacing the costly construction work that was previously done using hydraulic excavators as construction machinery.The present invention can contribute to the creation of high-quality, highly productive farmland by improving poorly drained areas such as the mountainous regions and gravelly alluvial plains that are common in Japan. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic perspective view showing the overall configuration of an exemplary embodiment of an underdrain construction device. [Figure 1A] FIG. 1A is a schematic front view of the cutting blade unit of FIG. [Figure 2] 2(a) to 2(e) show the operation of the conventional culvert construction device shown in FIG. 1 in which only the inner soil lifting members are arranged and no outer soil lifting members are arranged. [Figure 3] 3(a) to 3(e) are cross-sectional views similar to those of FIG. 2, but show the operation when the underdrain construction device of the present invention shown in FIG. 1 is used. [Figure 4] Figures 4(a) to (e) are cross-sectional views similar to those of Figure 3, but show the operation when the inner and outer soil lifting members on both the left and right sides of the lower end of the vertical cutting blade are replaced with members of different sizes. [Figure 5] 5(a) to 5(e) are cross-sectional views schematically showing the construction procedure at each stage using the underdrain construction device shown in FIG. [Figure 6] 6(a) to 6(g) are cross-sectional views showing a method for adjusting the construction depth of the underdrain drainage by adjusting the insertion depth of the cutting blade unit and other components connected thereto in the underdrain construction device shown in FIG. 1 into the soil. [Figure 7] The cross-sectional views of Fig. 7(a) to (c) show the behavior of a stone or blade when the stone in the soil collides with the vertical cutting blade and the curved cutting blade of the cutting blade unit. [Figure 8] Figure 8(a) and (c) show the behavior of the culvert construction equipment when there is a huge buried object in the soil. [Figure 9] FIG. 9 is a schematic diagram of the structure of an underdrain constructed when the underdrain construction device shown in FIG. 1 was used in a field. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment of an underdrain construction device of the present invention will be described with reference to the drawings showing an example of the configuration of the present invention. A typical underdrain is a trench-like structure that includes a synthetic resin underdrain pipe with many holes that is buried in the soil, for example, at a depth of about 60 cm to 90 cm, and a highly permeable hydrophobic material buried above it. The underdrain pipe burying device of the present invention is a machine that constructs a desired underdrain in the soil by being towed by a tractor or the like.

[0016] In this specification, the traveling direction of the underdrain construction device is referred to as the "forward direction," and the opposite direction is referred to as the "rearward direction." In addition, the direction perpendicular to the fore-and-aft direction of the underdrain construction device is referred to as the left-right direction, and when facing forward, these are referred to as the "right" side and the "left" side.

[0017] The configuration and operation of an underdrain construction device 10 of the present invention will be described below with reference to Figures 1 to 9. Note that in the description, multiple figures may be referenced, and in the explanation of each figure, reference may be made to symbols in other figures.

[0018] Figure 1 is a schematic perspective view showing the overall configuration of an exemplary embodiment of an underdrain construction device 10. The underdrain construction device 10 is composed of an aboveground traveling section including an equipment frame 11 that is towed and travels above ground, and an underground construction section that is located below the equipment frame 11 and inserted into the soil to construct underdrain drainage. The traveling direction of the underdrain construction device 10 is indicated by an arrow.

[0019] A three-point connection having one upper top link 12 and two lower lower links 13 is provided on the front of the device frame 11. The three-point connection is used to connect to a towing machine such as a farming machine, such as a tractor, or a construction machine, such as a bulldozer, owned by a farmer. When the device frame 11 is towed by the towing machine and moves along the ground, the underground construction section also moves along the soil, constructing a culvert drainage system in the soil.

[0020] A rotating shaft 24, which is a cylindrical pipe extending across substantially the entire width of the device frame 11 in the left-right direction, is disposed behind the three-point connection of the device frame 11. Both left and right ends of the rotating shaft 24 are inserted into and fixed to cylindrical rotating shaft holding fixed guides 25 disposed on the left and right ends of the device frame 11, respectively. The rotating shaft holding fixed guides 25 are fixed integrally with the device frame 11. Each end of the rotating shaft 24 is fixed to the rotating shaft holding fixed guides 25 by appropriate fasteners or fixing means such as bolting, pinning, clamping, pressure clamping, or crimping.

[0021] The underground construction section located below is fixed to the rotating shaft 24. When the rotating shaft 24 and the rotating shaft holding fixed guide 25 are fixed to each other by a fastener or the like, the rotating shaft 24 cannot rotate relative to the rotating shaft holding fixed guide 25, i.e., the device frame 11. If a torque greater than a certain level is applied to the rotating shaft 24, for example, when the underground construction section collides with gravel, the fastener or the like between the rotating shaft 24 and the rotating shaft holding fixed guide 25 will break or the fixing pressure will be exceeded, and the connection between the rotating shaft 24 and the rotating shaft holding fixed guide 25 will be released. As a result, the rotating shaft 24 will become rotatable relative to the rotating shaft holding fixed guide 25, i.e., the device frame 11.

[0022] With this structure, even if excessive torque is applied to the rotating shaft 24, the excessive torque is not transmitted to the device frame 11, thereby preventing damage to the underdrain construction device 10 and the towing machine. This makes it possible to safely construct underdrainage in poorly drained farmland with gravel and other adverse conditions.

[0023] The upper end portion of the cutting blade unit 20 of the underground construction portion of the underdrain construction device 10 is attached to an intermediate position on the rotating shaft 24. This supports the cutting blade unit 20 from above so that it hangs from the rotating shaft 24. Details of the cutting blade unit 20 will be described later, but the upper vertical extension 21a of the vertical cutting blade 21 and the upper vertical extension 22a of the curved cutting blade 22 of the cutting blade unit 20 are inserted from below into a pair of cutting blade holders 23 fixed to the rotating shaft 24. The upper vertical extensions 21a, 22a are vertically slidable relative to the cutting blade holder 23 and are fixed to the cutting blade holder 23 at the desired vertical position using an appropriate fixture. The construction depth of the underdrain can be adjusted by adjusting the vertical position of the cutting blade unit 20.

[0024] As shown in Figure 1, the cutting blade unit 20 is located at the forefront of the underground construction section. Figure 1A is a schematic front view of the cutting blade unit 20. The cutting blade unit 20 has a vertical cutting blade 21 and a curved cutting blade 22 arranged at a predetermined distance from each other in the left-right direction. The vertical cutting blade 21 has a flat vertical plate portion 21b extending vertically, a blade provided along the front edge of the vertical plate portion 21b, and an upper vertical extension portion 21a extending upward from the vertical plate portion 21b.

[0025] The bent cutting blade 22 comprises a bent plate portion consisting of a flat upper vertical plate portion 22b extending parallel to the vertical plate portion 21b of the vertical cutting blade 21 at a predetermined distance, and a flat lower inclined plate portion 22c extending obliquely downward from the lower end of the upper vertical plate portion 22b so as to approach the vertical cutting blade 21. That is, the bent cutting blade 22 is bent inward at a bend line extending approximately in the front-to-rear direction at a vertically intermediate position. The bending angle is, for example, approximately 120° to 150°. The bent cutting blade 22 further comprises a blade provided along the front edge of the bent plate portion. The bent cutting blade 22 further comprises an upper end vertical extension portion 22a extending upward from the upper vertical plate portion 22b.

[0026] Each of the vertical cutting blade 21 and the curved cutting blade 22 faces forward and is preferably a wavy blade that is concavely curved overall. The lower ends of the vertical cutting blade 21 and the curved cutting blade 22 are spaced apart by a predetermined distance. As shown in Fig. 1A, the overall shape of the cutting blade unit 20 is approximately U-shaped when viewed from the front.

[0027] Here, in this specification, the opposing surfaces of the vertical cutting blade 21 and the curved cutting blade 22 are referred to as the "inner surfaces", the side with the inner surfaces is referred to as the "inner side", the opposite surface is referred to as the "outer surface", and the side with the outer surface is referred to as the "outer side".

[0028] As shown in FIG. 1, the soil lifting unit 30 is disposed at the lower end of the cutting blade unit 20. The soil lifting unit 30 is composed of an inner soil lifting member 35 and an outer soil lifting member 36. The inner soil lifting member 35 is disposed inside the vertical cutting blade 21 at the lower end of the vertical cutting blade 21. The inner soil lifting member 35 is formed from an inner front blade 31 equipped with a blade facing forward and an inner soil lifting plate 32 connected to the rear of the inner front blade 31, and is a plate-like member that is rectangular in shape in plan view and slopes upward toward the rear as a whole.

[0029] The width of the inner soil lifting member 35 in the left-right direction is equal to the distance between the lower ends of the vertical cutting blade 21 and the curved cutting blade 22. The length of the inner soil lifting member 35 in the front-rear direction is set as needed. In addition, multiple inner soil lifting members 35 of different lengths (i.e., multiple inner soil lifting plates 32 of different lengths) can be prepared, and appropriate ones can be selected and installed interchangeably. It can also be said that the inner soil lifting member 35 connects the lower ends of the vertical cutting blade 21 and the curved cutting blade 22 together.

[0030] On the other hand, the outer soil lifting member 36 is disposed outside the vertical cutting blade 21 at the lower end of the vertical cutting blade 21. The outer soil lifting member 36 is formed from an outer front blade 33 having a blade facing forward and an outer soil lifting plate 34 connected to the rear of the outer front blade 33, and is a plate-like member that is rectangular in plan view as a whole and slopes upward toward the rear.

[0031] The outer soil lifting members 36 are set not only in length in the front-rear direction but also in width in the left-right direction as required. In addition, a plurality of outer soil lifting members 36 with different lengths and / or widths (i.e., a plurality of outer soil lifting plates 34 with different lengths and / or widths) can be prepared, and appropriate ones can be selected from among them and attached interchangeably.

[0032] If the inner soil lifting member 35 and the outer soil lifting member 36 have the same width, they can be installed interchangeably.

[0033] The inner soil lifting member 35 and outer soil lifting member 36 included in the soil lifting unit 30 are arranged on the inside and outside, i.e., on both the left and right sides, of the lower end of the vertical cutting blade 21. This configuration has the effect of balancing the left and right pressures acting on the cutting blade unit 20, thereby contributing to maintaining an optimal horizontal posture of the culvert construction device 10. As the inner soil lifting member 35 and outer soil lifting member 36, which have an upward slope toward the rear, advance, the entire soil on both sides of the vertical cutting blade 21 is lifted, causing the soil on both sides of the vertical cutting blade 21 to be crushed and softened. "Softening" refers to the soil becoming softer as the proportion of air in the soil increases.

[0034] As shown in Figure 1, a material burying unit 40 is arranged in series behind the vertical cutting blade 21. The cutting blade unit 20 and the material burying unit 40 are integrated by an appropriate connecting means. Therefore, when the vertical position of the cutting blade unit 20 is adjusted as described above, the position of the material burying unit 40 is also adjusted at the same time.

[0035] The material burying unit 40 includes an underdrain pipe burying guide 41 and a hydrophobic material burying guide 42 arranged in series in the front-to-rear direction. The underdrain pipe burying guide 41 is tubular, and preferably the cross section of the pipe has a triangular shape with the front end being the apex of a triangle. The shape of this underdrain pipe burying guide 41 makes it easy to excavate the soil as it moves forward. In addition, the entire soil on both sides of the vertical cutting blade 21 is softened, making it easy to insert the material burying unit 40 into the soil. In addition, the softened soil stabilizes the movement of the underdrain construction device 10.

[0036] The tubular underdrain pipe burying guide 41 extends obliquely downward from its upper opening protruding above ground along the rear edge of the vertical plate portion 21b of the vertical cutting blade 21, with its lower opening facing approximately rearward as a delivery outlet 41a. An underdrain pipe loading reel 44 around which an underdrain pipe (not shown) is wound is attached to the right rear of the device frame 11 of the aboveground proceeding section. At the same time as the material burying unit 40 is inserted into the soil, the underdrain pipe continuously taken out from the underdrain pipe loading reel 44 is inserted through the upper opening of the underdrain pipe burying guide 41, fed downward, and then fed out through the delivery outlet 41a and installed.

[0037] The hydrophobic material burying guide 42 is arranged in series behind the underdrain pipe burying guide 41. A hydrophobic material feeding guide 43 is arranged on the ground proceeding section above the hydrophobic material burying guide 42. The hydrophobic material feeding guide 43 is shaped like an inverted truncated pyramid and is open at the top and bottom. Hydrophobic material (not shown) is fed and loaded from the upper opening of the hydrophobic material feeding guide 43, and is supplied to the hydrophobic material burying guide 42 from the lower opening. The hydrophobic material is then dropped from the hydrophobic material burying guide 42. The dropped hydrophobic material covers the top of the underdrain pipe that was installed just before. In this way, an underdrain drainage can be constructed with a single pass of the underdrain construction device 10.

[0038] 2 to 4, the operation of the cutting blade unit 20 and the soil lifting unit 30 of the underdrain construction device 10 shown in Fig. 1 will be described. These schematic soil cross-sectional views show a cross section of the underdrain construction device 10 viewed in the direction opposite to the traveling direction (i.e., from front to rear).

[0039] The cross-sectional views of Figures 2(A) to 2(E) show the operation of the conventional culvert construction device 10 shown in Figure 1, in which only the inner soil lifting member 35 is arranged, and the outer soil lifting member 36 is not arranged. Figures 2(A) to 2(E) show the construction sequence. The pressure related to the cutting blade unit 20 and the soil lifting unit 30 at each stage will be explained with reference to these figures. The pressure exerted by the cutting blade unit 20 on the soil is indicated by the symbol P, and the pressure received by the cutting blade unit 20 from the soil is indicated by the symbol p. The subscripts of the symbols P and p distinguish between pressures at different locations and / or pressures in different directions. The thickness or length of the arrows indicating pressures schematically indicates the strength of the pressure. While pressure generally represents the force per unit area, in this specification, it is used to mean the pushing force applied to the entire target surface.

[0040] By inserting the roughly U-shaped cutting blade unit 20 into the dense soil consisting of topsoil and subsoil as shown in Figure 2(A), the soil in the area surrounded by the vertical cutting blade 21 and the curved cutting blade 22 is cut as shown in Figure 2(B), forming a cut soil lump X. As shown in Figure 2(C), pressure Pa applied to the soil by the inner soil lifting member 35 and pressure Pb applied to the soil by the lower inclined plate portion 22c of the curved cutting blade 22 act on the cut soil lump X.

[0041] As a result, as shown in Figure 2(d), the soil of the cut soil mass X is crushed (S) and the soil is softened and expanded. In particular, because the pressure Pa applied to the soil by the inner soil lifting plate member 35 is greater than the pressure Pb applied to the soil by the lower inclined plate portion 22c, crushing (S) of the soil occurs above the inner soil lifting plate member 35, causing the soil to soften and expand. As a result, the cut soil mass X inside the approximately U-shaped cutting blade unit 20 is softened and expanded, particularly above the inner soil lifting plate member 35 of the vertical cutting blade 21. However, in contrast to this, just outside the vertical cutting blade 21, the soil conditions are such that the dense soil remains intact and uncrushed.

[0042] Under the soil conditions shown in Figure 2(D), the material burying unit 40, which includes the underdrain pipe burying guide 41 and the hydrophobic material burying guide 42, arranged in series behind the vertical cutting blade 21, has a wide width in the left-right direction. As a result, as shown in Figure 2(E), the material burying unit 40 passes through the soil, pushing apart the softened soil above the inner soil lifting plate member 35 and the dense soil outside the vertical cutting blade 21. As a result, the material burying unit 40 experiences an imbalance between the large pressure (pl) to the left and the small pressure (pr) to the right from the soil. This can lead to the underdrain construction device 10 tilting relative to the horizontal and bending laterally relative to the direction of travel. Therefore, a structural improvement is needed to reduce the pressure the material burying unit 40 receives from the soil and to equalize the pressure on both sides.

[0043] Figures 3(a) to 3(e) are cross-sectional views similar to those of Figure 2, but show the operation when using the underdrain construction device 10 of the present invention shown in Figure 1. As the soil lifting unit 30, an inner soil lifting member 35 including an inner front blade 31 and an inner soil lifting plate 32, and an outer soil lifting member 36 including an outer front blade 33 and an outer soil lifting plate 34 are arranged.

[0044] By inserting a roughly U-shaped cutting blade unit 20 equipped with inner soil lifting members 35 and outer soil lifting members 36 into the dense soil shown in Figure 3(A), the soil in the area surrounded by the vertical cutting blade 21 and curved cutting blade 22 is cut, as shown in Figure 3(B), to form a cut soil lump X. The cut soil lump X has the function of preventing the culvert construction device from floating up due to its weight and facilitating its insertion into the deep soil layer.

[0045] As shown in Figure 3(c), around the cutting blade unit 20, pressure Pa is applied to the soil by the inner soil lifting member 35, and pressure Pb is applied to the soil by the lower inclined plate portion 22c of the curved cutting blade 22. In addition, pressure Pc is applied to the soil by the outer soil lifting member 36. As a result, soil fracture S occurs not only on the cut soil mass X but also on the outside of the vertical cutting blade 21, causing the soil to swell and soften.

[0046] In particular, as shown in Figure 3(e), the pressure Pa applied to the soil by the inner soil lifting member 35 and the pressure Pc applied to the soil by the outer soil lifting member 36 are large, so soil fractures S occur above the inner soil lifting member 35 and the outer soil lifting member 36, respectively, causing the soil to swell and soften.

[0047] Under the soil conditions shown in Figure 3(D), the material burial unit 40, which includes the underdrain pipe burial guide 41 and the hydrophobic material burial guide 42 arranged in series behind the vertical cutting blade 21, is wide in the left-right direction, but because both sides of the vertical cutting blade 21 are swollen and softened, the left-right balance between the pressure pl that the material burial unit 40 receives from the soil to the left and the pressure pr that it receives to the right is roughly the same, as shown in Figure 3(E), and horizontal balance can be maintained. Therefore, the underdrain construction device 10 does not tilt relative to the horizontal or bend sideways relative to the direction of travel, making it possible to construct desirable underdrain drainage.

[0048] According to the underdrain construction device 10 of the present invention, the soil is crushed and softened all over in this way, and the reaction force can be used to facilitate the insertion into the soil of the entire underground construction section including the cutting blade unit 20 and the material burying unit 40. Furthermore, by softening the entire soil, the progress of the underdrain construction device 10 is stabilized.

[0049] 4(A), (B), (C), and (D) are cross-sectional views similar to those of FIG. 3, but show the operation when the inner soil lifting members 35 and the outer soil lifting members 36 on both the left and right sides of the lower end of the vertical cutting blade 21 are replaced with members of different sizes. By changing the sizes, it is possible to adjust the pressure Pa that the inner soil lifting members 35 apply to the soil and the pressure Pc that the outer soil lifting members 36 apply to the soil. As a result, the leftward pressure pl and the rightward pressure pr that the material burial unit 40 receives from the soil can be made equal and can be offset.

[0050] In Figure 4(A), the sum of the pressure Pa applied to the soil by the inner soil lifting member 35 and the pressure Pb applied to the soil by the lower inclined plate portion 22c of the curved cutting blade 22 is smaller than the pressure Pc applied to the soil by the outer soil lifting member 36, so a rightward pressure pr is applied from the soil to the vertical cutting blade 21. In other words, the soil conditions are tighter on the inside than on the outside. To adjust for this, as shown in Figure 4(B), the inner soil lifting member 35 is made longer (for example, by lengthening the inner soil lifting plate 32), thereby increasing the area and increasing the pressure Pa applied to the soil by the inner soil lifting member 35. As a result, left and right balance can be achieved.

[0051] In Figure 4(C), the sum of the pressure Pa applied to the soil by the inner soil lifting member 35 and the pressure Pb applied to the soil by the lower inclined plate portion 22c of the curved cutting blade 22 is greater than the pressure Pc applied to the soil by the outer soil lifting member 36, resulting in a leftward pressure Pl being applied to the vertical cutting blade 21 from the soil. In other words, the soil is tighter on the outside than on the inside. To adjust for this, as shown in Figure 4(D), the area of ​​the outer soil lifting member 36 is increased (for example, by increasing the width of the outer front blade 33 and the outer soil lifting plate 34), thereby increasing the pressure Pc applied to the soil by the outer soil lifting member 36. As a result, left and right balance can be achieved.

[0052] 5(A) to 5(E) are cross-sectional views schematically illustrating the construction procedure at each stage using the underdrain construction device 10 shown in FIG. 1. By inserting a roughly U-shaped cutting blade unit 20 into the dense soil consisting of topsoil and subsoil shown in FIG. 5(A), the soil in the area surrounded by the vertical cutting blade 21 and the curved cutting blade 22 is cut, as shown in FIG. 5(B), to form a cut soil mass X. In particular, a narrow groove is formed by the vertical cutting blade 21, and the soil lifting unit 30, consisting of an inner soil lifting member 35 and an outer soil lifting member 36 arranged on both the left and right sides of the lower end of the vertical cutting blade 21, lifts the soil above them with their respective rectangular upper surfaces in a plan view, thereby crushing the lifted soil S. As a result, the soil, especially around the vertical cutting blade 21, is softened and swollen.

[0053] Next, as shown in Figure 5 (c), the material burying unit 40, which includes a culvert pipe burying guide 41 and a hydrophobic material burying guide 42 arranged in series behind the vertical cutting blade 21, moves forward while easily excavating and spreading the soil in the softened area.

[0054] At the same time, as shown in Figure 5 (d), underdrain pipe T, which has been supplied from an aboveground underdrain pipe loading reel 44 through an underdrain pipe burying guide 41, is placed at the bottom of the swelling and softening section. Immediately afterwards, the lower opening of an inverted truncated pyramid-shaped hydrophobic material feeding guide 43 located at the top of hydrophobic material burying guide 42 opens, and hydrophobic material F is supplied through hydrophobic material burying guide 42. The hydrophobic material F is buried above the underdrain pipe T at a certain thickness and height. This completes the basic structure of underdrain drainage U.

[0055] At the time of Figure 5(d), an upwardly open trench remains in the part corresponding to the topsoil above the underdrain drainage U. Thereafter, as shown in Figure 5(e), the trench is backfilled and leveled W by plowing with a rotary or the like to complete the underdrain drainage U for the farmland. The underdrain drainage U is constructed at a position where the vertical cutting blade 21 passes when viewed from the front. The position of the lower end of the vertical cutting blade 21 is the position below the underdrain pipe T.

[0056] 6(a) to 6(g) are cross-sectional views showing a method for adjusting the construction depth of the underdrain drainage U by adjusting the insertion depth of the cutting blade unit 20 and other components connected thereto in the underdrain construction device 10 into the soil.

[0057] By inserting a roughly U-shaped cutting blade unit 20 into the dense soil consisting of topsoil and subsoil as shown in Figure 6(A), the soil in the area surrounded by the vertical cutting blade 21 and the curved cutting blade 22 is cut as shown in Figure 6(B), forming a cut soil mass X. After that, a culvert drainage U is constructed as shown in Figure 6(E) according to the construction procedure shown in Figure 5.

[0058] In Figure 6(c), the vertical positions of the pair of upper vertical extensions 21a, 22a of the cutting blade unit 20 are lowered, thereby increasing the insertion depth of the cutting blade unit 20. In Figure 6(d), the vertical positions of the pair of upper vertical extensions 21a, 22a of the cutting blade unit 20 are higher, thereby decreasing the insertion depth of the cutting blade unit 20. The vertical positions of the pair of upper vertical extensions 21a, 22a are adjusted by changing the fixed positions relative to the cutting blade holder 23 shown in Figure 1. As a result, a culvert drainage U at a deep position as shown in Figure 6(f), or a culvert drainage U at a shallow position as shown in Figure 6(g), can be constructed.

[0059] The cross-sectional views of FIGS. 7(a) to 7(c) show the behavior of a stone or blade when the stone in the soil collides with the vertical cutting blade 21 and the curved cutting blade 22 of the cutting blade unit 20. As shown in FIG.

[0060] The stone Ra in the cutting blade unit 20 (between the vertical cutting blade 21 and the curved cutting blade 22) in Figure 7(A) does not interfere with construction at all. The size of the stone that exhibits this behavior is generally up to about 30 cm in diameter. Stone Rb, which is positioned to collide with the vertical cutting blade 21 in Figure 7(a), tends to move through the soil, especially since the surrounding soil is being crushed S, and moves into the softened cut soil mass X. The size of stones that exhibit this behavior is generally up to about 30 cm in diameter. Stones Rc located at the position where they will collide with the lower inclined plate of the curved cutting blade 22 in Figure 7(a) tend to move through the soil and may move into the softened cut soil mass X. The size of stones that exhibit this behavior is generally up to about 30 cm in diameter. The stone Rd in the position where it will collide with the lower inclined plate portion of the curved cutting blade 22 in Figure 7(c) is located slightly outside and may be somewhat deep. In this case, the cutting blade unit 20 moves up and floats up to avoid the stone. The blade of the lower inclined plate portion is particularly prone to slippage due to its slanted orientation. The size of the stone that exhibits this behavior can be up to about 30 cm in diameter, or even larger.

[0061] As the soil is crushed and softened, the stones in the soil become more mobile, so that when they collide with the cutting blade unit 20, the stones move to avoid the cutting blades 21 and 22. Alternatively, the cutting blade unit 20 can easily rise to avoid the stones. As a result, the progress of the culvert construction device 1 is not impeded by stones, and it can continue to travel.

[0062] 8(A) and 8(B) show the behavior of the culvert construction device 10 when there is a large stone or buried object Re in the soil. As shown in FIG. 8(A), the cutting blade unit 20 and the material burying unit 40 are fixed to the rotating shaft 24, which is a cylindrical pipe, via the cutting blade holder 23. This is done by inserting the upper vertical extensions of the vertical cutting blade 21 and the curved cutting blade 22 into the cutting blade holder 23 from below and fixing them in appropriate positions. The left and right ends of the rotating shaft 24 are each fixed by appropriate fixing means to a rotating shaft holding fixed guide 25 that is integral with the device frame 11. Therefore, the rotating shaft 24 is normally unable to rotate with respect to the rotating shaft holding fixed guide 25.

[0063] As shown in Figure 8(A), when a large stone or buried object Re in the soil collides with the vertical cutting blade 21 and the curved cutting blade 22, an excessive load exceeding a certain level is applied to the rotating shaft 24 of the cylindrical pipe, generating a large torque on the rotating shaft 24 of the cylindrical pipe. As a result, the fixing means that fixes the rotating shaft 24 to the rotating shaft holding fixed guide 25 breaks or disappears, and the connection between the rotating shaft 24 and the rotating shaft holding fixed guide 25 is released. This allows the rotating shaft 24 to rotate relative to the rotating shaft holding fixed guide 25. The excessive load is released by the rotation of the cutting blade unit 20 and the material burying unit 40 together with the rotating shaft 24. In this way, damage to the underdrain construction device 10 and the towing vehicle due to the excessive load can be prevented.

[0064] Examples of the present invention are described below. Example 1 Fig. 9(A) is a schematic cross-sectional view showing the results of a test construction of underdrain drainage using the underdrain pipe burying device 10 shown in Fig. 1. The test conditions are as follows. Test location: Field at Nishiaiuchi 22, Kitami City, Hokkaido Tractor: New Holland T6.150 wheel tractor, 150 horsepower Soil conditions: Gravelly gray lowland soil Soil composition: The topsoil is 10cm deep, and below that is a gravelly soil layer consisting of about 20% pebbles 20cm in diameter. The soil is tightly compacted and has poor drainage.

[0065] In the treatment area of ​​the construction test, the cutting blade unit 20 and material burial unit 40 could be inserted to the expected depth. The construction speed was 1 km / h, and the tractor could be constructed without slipping. Construction was possible at a maximum speed of 2 km / h, but a speed of up to 1.5 km / h was appropriate, taking into account the supply of materials such as hydrophobic materials. As shown in Figure 9(A), the shape of the underdrain drainage U after construction can be seen, with the underdrain pipe T buried to a depth of 77 cm below the pipe, which is the expected depth. The width of the underdrain drainage U is 7 cm. This confirmed the effectiveness of the underdrain construction device 10 of the present invention.

[0066] <Example 2> 9(a) shows the results of checking the operation of the underdrain construction device 10 in different soil conditions in a farm field in another region. The test conditions are as follows. Test location: Western Development Agriculture's rice paddy field in Yokokawame 18, Waga-cho, Kitakami City, Iwate Prefecture Tractor: Yanmar CT1380 crawler tractor 138 horsepower Soil conditions: Gravelly gray plateau soil Soil composition: The topsoil is 10cm deep, and below that a gravelly soil layer consisting of 30% gravel 10-20cm in diameter continues to the lower layers. There is spring water and drainage is poor.

[0067] The treatment area for the construction test had spring water, was humid, and had poorly drained soil, so construction was shallow to ensure machine travel. The cutting blade unit 20 and material burial unit 40 were able to be inserted despite the large amount of gravel, and an underdrain drainage U was constructed with the underdrain pipe T and hydrophobic material F properly buried. Because the field was humid, construction was possible at a construction speed of 1 km / h. As shown in Figure 9(A), the shape of the underdrain drainage U after construction was such that the underdrain pipe T was buried 47 cm below the pipe, and the width of the underdrain drainage was 7 cm. This confirmed the effectiveness of the underdrain construction device 10 of the present invention.

[0068] <Comparative Example 1> The soil conditions at an unconstructed site in a test field in Kitami City, Hokkaido, where construction was not performed using the underdrain construction device 10 of the present invention, were as follows. Test location: Field at Nishiaiuchi 22, Kitami City, Hokkaido Soil conditions: Gravelly gray lowland soil Soil layer composition: There is a lot of gravel from the surface, and from 10cm into the topsoil, a gravelly soil layer consisting of about 20% gravel with a diameter of 20cm continues to the lower layers. The entire soil layer is tightly compacted, and drainage is poor. Below the surface 10cm, the soil is dense, with measurements using a penetration soil hardness tester exceeding 2.5MPa. After rainfall, there are scattered areas on the surface where water accumulates and crops wither.

[0069] <Comparative Example 2> The soil conditions at an unconstructed site in a test field in Kitakami City, Iwate Prefecture, where construction was not performed using the underdrain construction device 10 of the present invention, were as follows. Test location: Western Development Agriculture's rice paddy field in Yokokawame 18, Waga-cho, Kitakami City, Iwate Prefecture Soil conditions: Gravelly gray plateau soil Soil layer composition: The topsoil is 10cm deep, and below that a gravelly soil layer consisting of approximately 30% gravel 10-20cm in diameter continues to the lower layers. There is spring water and drainage is poor. In rainy weather, water quickly accumulates on the surface, making it desirable to install an underdrain.

[0070] As described above, the underdrain construction device of the present invention is equipped with a vertical cutting blade and a curved cutting blade that can change their vertical position in the soil, arranged in parallel in the left-right direction. This allows the underdrain pipe burying device to be towed by a farmer's tractor, and even in dense soil layers, the two blades can reliably cut through the soil, allowing the underdrain pipe burying device to be inserted deep into the soil, and the underdrain pipe and hydrophobic material can be stably buried to a specified depth of up to about 75 cm. This can improve the drainage of poorly drained farmland. [Explanation of symbols]

[0071] 10. Culvert construction equipment 11 Device frame 12 Top link of three-point connection 13 Lower link of three-point connection 20 Cutting blade unit 21 Vertical cutting blade 21a Upper vertical extension 21b Vertical plate section 22 Bent cutting blade 22a Upper vertical extension 22b Upper vertical plate 22c Lower inclined plate part 23 Cutting blade holder 24 Rotation Axis 25 Rotation axis holding fixed guide 30 Soil Lifting Unit 31 Inner front blade 32 Inner soil lifting plate 33 Outer front blade 34 Outside soil lifting plate 35 Inner soil lifting member 36 Outer soil lifting member 40 Material Burial Unit 41 Underdrain Pipe Burial Guide 41a Underdrain pipe outlet 42 Hydrophobic Material Burial Guide 43 Hydrophobic Material Insertion Guide 44 Culvert pipe loading reel P Pressure on the soil Pa Pressure due to inner soil lifting plate Pb Pressure from the lower inclined plate of the curved cutting blade Pc Pressure from outer soil lifting plate p Pressure from the soil pl Pressure from the soil to the left pr Pressure from the soil to the right S Soil crushing F Hydrophobic material T culvert pipe U Underdrain drainage R stone Ra Stone inside the cutting blade unit Rb: Stones that collide with the vertical cutting blade Rc Stones that are in a position to collide with the lower inclined plate of the curved cutting blade Rd Stones that are in a position to collide with the lower inclined plate of the curved cutting blade Re: Large stones or buried objects colliding with the cutting blade unit W Backfilling and leveling X cutting clod

Claims

1. A culvert construction device that constructs culvert drainage in soil by being towed and moving forward, a vertical cutting blade (21) having a vertical plate portion (21b) extending in the vertical direction and a blade provided along the front edge of the vertical plate portion (21b); a bending cutting blade (22) including a bending plate portion including an upper vertical plate portion (22b) extending vertically in parallel with the vertical plate portion (21b) of the vertical cutting blade (21) at a predetermined interval in the left-right direction perpendicular to the front-rear direction of the culvert construction device and a lower inclined plate portion (22c) extending obliquely downward from the lower end of the upper vertical plate portion (22b) so as to approach the vertical cutting blade (21), and a blade provided along the front edge of the bending plate portion; an inner soil lifting member (35) that is disposed inside a surface facing the curved cutting blade (22) in the left-right direction of the vertical cutting blade (21) at the lower end of the vertical cutting blade (21), includes an inner front blade (31) facing forward and an inner soil lifting plate (32) continuing behind the inner front blade (31), and is rectangular in plan view and has an upward slope toward the rear; an outer soil lifting member (36) that is disposed on the outside of the lower end of the vertical cutting blade (21) on a surface opposite to the surface facing the curved cutting blade (22) in the left-right direction of the vertical cutting blade (21), includes an outer front blade (33) facing forward and an outer soil lifting plate (34) continuing behind the outer front blade (33), and is rectangular in plan view and has an upward slope toward the rear; and a material burying unit (40) disposed behind the vertical cutting blade (21) and supplying an underdrain pipe (T) and a hydrophobic material (F), As the device advances, the soil is cut by the vertical cutting blade (21) and the curved cutting blade (22), the soil above is lifted by the inner soil lifting member (35) and the outer soil lifting member (36), crushed, and softened, and then the material burying unit (40) supplies the underdrain pipe (T) and the hydrophobic material (F).

2. The culvert construction device according to claim 1, characterized in that the length in the front-rear direction and / or the width in the left-right direction of each of the inner soil lifting member (35) and the outer soil lifting member (36) are set so that the rightward pressure (pr) and the leftward pressure (pl) that the vertical cutting blade (21) receives from the soil are approximately the same.

3. 3. The underdrain construction device according to claim 1, wherein the inner soil lifting member (35) is selected from a plurality of inner soil lifting members (35) having different lengths in the front-to-rear direction and is attached in an exchangeable manner.

4. The underdrain construction device according to any one of claims 1 to 3, characterized in that the outer soil lifting member (36) is selected from a plurality of outer soil lifting members (36) having different lengths in the front-to-rear direction and / or different widths in the left-to-right direction and is attached in an exchangeable manner.

5. The underdrain construction device according to any one of claims 1 to 4, characterized in that it has a means for adjusting the fixed positions of the vertical cutting blade (21) and the curved cutting blade (22) in the vertical direction in order to adjust the construction depth of the underdrain drainage.

6. The culvert construction device according to any one of claims 1 to 5, characterized in that the upper ends of the vertical cutting blade (21) and the curved cutting blade (22) are fixed to a rotating shaft (24), and the rotating shaft (24) is fixed so as not to rotate until a torque of a certain level or more is applied, and becomes rotatable when a torque of the certain level or more is applied.

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