Mobile soil retaining device, and burying method using mobile soil retaining device

Abstract

To provide a mobile soil retaining device, a burying method using the mobile soil retaining device capable of reducing drawback on frontward movement including traction.SOLUTION: A mobile soil retaining device is provided with: a pair of soil retaining panels supported in a state of facing each other with a specific distance therebetween to form a working area W; blade members provided on a front side of the pair of soil retaining panels in a moving direction of each of them; and plates provided on a part of each outside surface of the pair of soil retaining panels. Friction coefficient between outside surfaces of the plates and soil is lower than that between the outside surfaces of the soil retaining panels and soil, outside surfaces included in the same planar surface with the outside surfaces of the plates are formed on the blade members, and the outside surfaces of the plates are formed outside further than the outside surfaces of the soil retaining panels in a direction in which the pair of soil retaining panels face each other.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a mobile earth retaining device that can perform piping work within the internal space while protecting the side walls of an excavated trench during construction (burial work) to lay buried pipes such as power cable protection pipes, and to an burial construction method using the mobile earth retaining device. [Background technology]

[0002] Conventionally, there is known a mobile earth retaining device that can perform piping work within an internal space while protecting the side walls of an excavated trench during construction (burial construction) of buried pipes such as power cable protection pipes (see, for example, Patent Document 1). The mobile earth retaining device described in Patent Document 1 includes a pair of sheet pile units that contact the side walls of an excavated trench to retain earth, and connecting members that connect the sheet pile units together.

[0003] In the burial work, first, a trench is excavated for installing the mobile earth retaining device, and the mobile earth retaining device is installed in the trench. Next, a buried pipe is inserted into the work area inside the mobile earth retaining device and connected to the buried pipe that was laid earlier. Finally, the area in front of the mobile earth retaining device is excavated, the mobile earth retaining device is pulled forward by a backhoe, and the area behind the mobile earth retaining device is backfilled. This series of cycles is repeated in the burial work. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-21894 Summary of the Invention [Problem to be solved by the invention]

[0005] In this way, the mobile soil retaining device is towed forward, but there is a problem in that friction between the outer surface of the sheet pile unit and the side wall of the groove during towing is large, which hinders towing.

[0006] The present invention has been made to solve the above problems, and aims to provide a mobile earth retaining device that reduces obstacles to forward movement, including towing, and an embedding method using the mobile earth retaining device. [Means for solving the problem]

[0007] In order to solve the above problems, the mobile soil retaining device according to the present invention comprises: A mobile earth retaining device having a working area formed inside for laying buried pipes while moving an excavated trench in the excavation direction, A pair of retaining panels that are held facing each other at a predetermined distance and form the working area; A blade member provided on a front side of each of the pair of earth retaining panels along the movement direction; a plate installed on a portion of each of the outer surfaces of the pair of earth retaining panels; The coefficient of friction between the outer surface of the plate and the soil is lower than the coefficient of friction between the outer surface of the retaining panel and the soil, The blade member is formed with an outer surface that is included in the same plane as the outer surface of the plate, The outer surface of the blade member and the outer surface of the plate are characterized in that they are formed further outboard than the outer surfaces of the earth retaining panels in the direction in which the pair of earth retaining panels face each other. Effect of the Invention

[0008] According to the present invention, it is possible to reduce the hindrance to forward movement, including towing. [Brief description of the drawings]

[0009] [Figure 1] This is an oblique view of the mobile soil retaining device from diagonally forward. [Diagram 2] This is an oblique view of the mobile soil retaining device from diagonally behind. [Diagram 3] FIG. [Figure 4] FIG. [Diagram 5] FIG. [Figure 6] FIG. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] 13 is a partially enlarged schematic plan view of the area near the connection between the lower retaining panel on the right side and the lower blade member. FIG. [Figure 10] 1 is a flowchart of a buried pipe laying cycle process. [Figure 11] This is a specific example showing a buried pipe in contact with the inner surfaces of both soil inflow prevention plate-shaped members. [Figure 12] This is a specific example showing how a new buried pipe is connected to an existing buried pipe inside the retaining device, and then the retaining device is towed by a backhoe via a towing string. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] First Embodiment Hereinafter, a mobile earth retaining device according to an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view of the mobile earth retaining device according to the first embodiment, seen from an oblique front, and Fig. 2 is a perspective view of the mobile earth retaining device according to the first embodiment, seen from an oblique rear.

[0011] The mobile earth retaining device 100 according to the first embodiment is used to perform piping work in a working area W formed inside the mobile earth retaining device 100 while protecting the side walls of an excavated trench during construction (burial work) for laying buried pipes such as power cable protection pipes. As will be described later, the burial work progresses while the mobile earth retaining device 100 is moved forward. It is assumed that the mobile earth retaining device 100 is used in burial work on a scale in which a trench 1.5 to 2.0 m deep is excavated and buried pipes of φ125 to 200 mm are laid. However, various scales of the burial work (depth of the trench, diameter of the buried pipe, etc.) are not particularly limited and may be set appropriately.

[0012] In the following, the mobile earth retaining device 100 will be simply referred to as the "earth retaining device 100." In the following, for convenience, the front-rear direction, left-right direction, and up-down direction will be specified based on "front," "right," and "up" shown in Figs. 1 and 2. However, the relationship between these directions and the orientation of the earth retaining device 100 is not limited to the embodiment described below. Note that "up" shown in Figs. 1 and 2 does not refer to an absolute vertical direction, but rather to a direction perpendicular to the ground at the work site.

[0013] The three-dimensional shape of the earth retaining device 100 is approximately a rectangular parallelepiped overall. In the rectangular parallelepiped earth retaining device 100, both sides perpendicular to the left-right direction are closed, and both sides perpendicular to the front-rear direction and the up-down direction are open. The closed sides perpendicular to the left-right direction face the side walls of the trench (functioning as earth retaining walls), and the open front is the direction of travel. The space sandwiched between the two sides facing the side walls of the trench in the earth retaining device 100 constitutes the working area W.

[0014] All of the faces constituting the rectangular parallelepiped of the earth retaining device 100 are rectangular. The length of the rectangular parallelepiped of the earth retaining device 100 in the front-to-rear direction is the longest, the length in the left-to-right direction is the shortest, and the length in the up-to-down direction is longer than the left-to-right direction and shorter than the length in the front-to-back direction. However, the relationship of the lengths in each direction can be set appropriately and is not particularly limited.

[0015] The soil retaining device 100 is configured to be assembled (separable) from a lower unit 1 and an upper unit 2. In a use state, the lower unit 1 is placed on a work site, and the upper unit 2 is placed on the lower unit 1. The lower unit 1 and the upper unit 2 are fixed in a state of being in close contact with each other in the vertical direction using a fixing structure (not shown) formed between the lower unit 1 and the upper unit 2. As the fixing structure, for example, a rod-shaped pin is connected to the lower unit 1 via a predetermined chain, and a fitting hole into which the pin can be fitted is formed at a location of the upper unit 2 where the pin reaches. Then, the lower unit 1 and the upper unit 2 can be fixed by fitting the pin of the lower unit 1 into the fitting hole of the upper unit 2. Note that the specific content of the fixing structure formed between the lower unit 1 and the upper unit 2 can be set appropriately and is not particularly limited.

[0016] Fig. 3 is a right side view of the lower unit 1, Fig. 4 is a bottom view of the lower unit 1, Fig. 5 is a front view of the lower unit 1, Fig. 6 is a right side view of the upper unit 2, Fig. 7 is a plan view of the upper unit 2, and Fig. 8 is a front view of the upper unit 2. Note that in the following, for Figs. 3 to 8 as well, the front-rear direction, left-right direction, and up-down direction will be specified based on "front", "right", and "up" shown in Figs. 1 and 2.

[0017] Next, the lower unit 1 and the upper unit 2 will be described with reference to Figures 1 to 8. First, the lower unit 1 will be described. The lower unit 1 has a lower retaining panel 10, a lower horizontal support 11, a lower blade member 13, a lower side resin plate 14, a lower hanging metal fitting 15, a towing string-like body 16, a soil inflow prevention plate-like member 17, a lower bottom resin plate 18, and a positioning protrusion 19.

[0018] The lower unit 1 has two lower retaining panels 10. The lower retaining panels 10 are formed in a horizontally elongated rectangular shape. The two lower retaining panels 10 are fixed by lower horizontal supports 11 with one side of the panels facing each other at a predetermined distance. Therefore, a space is formed between the two fixed lower retaining panels 10. This space constitutes a part (lower side) of the working area W where workers can perform work related to laying buried pipes.

[0019] The long sides and short sides of the two fixed lower retaining panels 10 are parallel to each other. Furthermore, the front ends, rear ends, upper ends, and lower ends of the two fixed lower retaining panels 10 are aligned in the left-right direction.

[0020] The lower retaining panel 10, when in use (during burial work), serves as a retaining wall for the side wall of the excavated trench. Therefore, the lower retaining panel 10 is made of steel material that has a bending stress corresponding to the required earth pressure. However, the material of the lower retaining panel 10 can be appropriately selected as long as the material has a bending stress corresponding to the required earth pressure.

[0021] In addition, a pair of two lower rail portions 10a extending long in the front-rear direction are arranged in parallel at a predetermined distance in the vertical direction at the upper end of the outer surface of the lower earth-retaining panel 10. Similarly, a pair of two lower rail portions 10a extending long in the front-rear direction are arranged in parallel at a predetermined distance in the vertical direction at a position slightly upward from the vertical center of the outer surface of the lower earth-retaining panel 10 and slightly upward from the lower end. The vertical intervals between the two lower rail portions 10a in each pair are the same. The vertical interval between the two lower rail portions 10a in each pair is approximately equal to the short-side length of the lower side resin plate 14 described later.

[0022] The lower rail portion 10a is formed from approximately near the front tip of the lower retaining panel 10 to approximately near the rear tip. The front tip and rear tip of each pair of two lower rail portions 10a are aligned in the vertical direction. Furthermore, the vertical distance between the lower side of the pair of two lower rail portions 10a arranged relatively higher and the upper side of the pair of two lower rail portions 10a arranged relatively in the center is approximately the same as the vertical distance between the lower side of the pair of two lower rail portions 10a arranged relatively in the center and the upper side of the pair of two lower rail portions 10a arranged relatively lower.

[0023] The cross-sectional shape of the lower rail portion 10a perpendicular to the front-rear direction (extension direction) is constant along the front-rear direction. The cross-sectional shape is a substantially rectangular shape with the long side extending in the left-right direction and the short side extending in the up-down direction.

[0024] Between each pair of two lower rail portions 10a, five lower partition portions 10b are arranged at equal intervals along the front-rear direction. The lower partition portion 10b arranged most forward among the five lower partition portions 10b is arranged at the front end of the lower rail portion 10a, and the lower partition portion 10b arranged most rearward among the five lower partition portions 10b is arranged at the rear end of the lower rail portion 10a. The interval between adjacent lower partition portions 10b in the front-rear direction is approximately equal to the length of the long side of a lower side resin plate 14 described later.

[0025] The lower partition 10b is formed from the pair of upper lower rails 10a to the lower lower rails 10a. The cross-sectional shape of the lower partition 10b perpendicular to the up-down direction is constant along the up-down direction. The cross-sectional shape is substantially rectangular with the long side extending in the front-rear direction and the short side extending in the left-right direction.

[0026] Furthermore, the left-right length of the lower rail portion 10a (the length from the outer surface of the lower retaining panel 10 to the outer tip of the lower rail portion 10a) and the left-right length of the lower partition portion 10b (the length from the outer surface of the lower retaining panel 10 to the outer tip of the lower partition portion 10b) are approximately identical.

[0027] The space formed by each pair of two lower rail portions 10a, each pair of two lower partition portions 10b adjacent in the front-to-rear direction, and the outer surface of the lower retaining panel 10 constitutes a lower fitting recess 10c into which the lower side resin plate 14 fits. Therefore, five lower fitting recesses 10c are arranged in the front-to-rear direction at the upper end of the outer surface of the lower retaining panel 10, slightly above the approximate center in the up-down direction, and slightly above the lower end.

[0028] The lower unit 1 has two lower horizontal supports 11. One lower horizontal support 11 is disposed between the front ends and upper sides of the two lower earth-retaining panels 10, and the other lower horizontal support 11 is disposed between the rear ends and upper sides of the two lower earth-retaining panels 10. The lower horizontal support 11 is fixed to the inner surfaces of both lower earth-retaining panels 10. Therefore, the distance between the two lower earth-retaining panels 10 is maintained by the left-right length of the lower horizontal support 11.

[0029] The lower horizontal support 11 has the role of preventing the lower earth-retaining panel 10 from collapsing inward when earth pressure acts on the lower earth-retaining panel 10. For this reason, the lower horizontal support 11 is made of steel material that has been given an axial force (compressive strength) along the left-right direction that corresponds to the required earth pressure. In addition, the lower horizontal support 11 is configured so that its overall length along the left-right direction can be adjusted.

[0030] The specific structure of the lower horizontal support 11 can be appropriately set within a range that can withstand the axial force (compressive strength) along the left-right direction corresponding to the required earth pressure, and the lower horizontal support 11 has two horizontal columnar parts 11a arranged at a predetermined distance in the vertical direction and two rib parts 11b connecting the two horizontal columnar parts 11a. Also, the material of the lower horizontal support 11 can be appropriately set as long as it is given the axial force (compressive strength) along the left-right direction corresponding to the required earth pressure.

[0031] The lower unit 1 has fifteen lower side resin plates 14. The lower side resin plates 14 are formed in a horizontally elongated rectangular shape that is approximately the same as the lower fitting recess 10c when viewed from the left-right direction. The lower side resin plates 14 are fitted into the lower fitting recess 10c formed on the outer surface of the lower earth-retaining panel 10. Therefore, five lower side resin plates 14 are arranged in parallel along the long side direction at the upper end of the lower earth-retaining panel 10, slightly upward from approximately the center in the vertical direction, and slightly upward from the lower end.

[0032] The thickness of the lower side resin plate 14 is slightly longer than the left-right length of the lower rail portion 10a (the length from the outer surface of the lower earth-retaining panel 10 to the outer tip of the lower rail portion 10a) and the left-right length of the lower partition portion 10b (the length from the outer surface of the lower earth-retaining panel 10 to the outer tip of the lower partition portion 10b). The lower side resin plate 14 fitted into the lower fitting recess 10c is bonded to the outer surface of the lower earth-retaining panel 10 by its entire inner surface. Therefore, the lower side resin plate 14 protrudes slightly outward from the left-right tips of the lower rail portion 10a and the lower partition portion 10b.

[0033] When the earth retaining device 100 is towed and advanced in the burial work, the lower side resin plate 14 located on the outer side in the left-right direction than the lower retaining panel 10 comes into contact with the side wall of the trench. The lower side resin plate 14 has a role of reducing the frictional force between the lower side resin plate 14 and the side wall (soil) of the excavated trench, compared to the case where the entire outer surface of the lower retaining panel 10 comes into contact with the side wall of the trench when the earth retaining device 100 is towed and advanced in the burial work. Therefore, the lower side resin plate 14 is made of a material having a static friction coefficient and a dynamic friction coefficient with the soil lower than those of the lower retaining panel 10. Furthermore, in the first embodiment, the lower side resin plate 14 is made of a material having high wear resistance. In the first embodiment, the lower side resin plate 14 is made of ultra-high molecular weight polyethylene (UHMW-PE). However, the material of the lower side resin plate 14 may be appropriately set within a range that satisfies the conditions that the static friction coefficient and the dynamic friction coefficient with the soil are lower than those of the lower retaining panel 10 and that the wear resistance is high. Furthermore, the lower side resin plate 14 may be made of a single material, or may be made of a compound or mixture of multiple materials.

[0034] The lower side resin plate 14 is fixed to the lower earth retaining panel 10 in a detachable manner by a predetermined lower bolt 14a being inserted from the outside into the lower side resin plate 14 and screwed into the lower earth retaining panel 10. In detail, the portion where the thread of the predetermined lower bolt 14a is formed is longer than the thickness (left-right length) of the lower side resin plate 14. Also, insertion holes (not shown) for inserting the predetermined lower bolt 14a are formed at two locations at approximately the center in the vertical direction of the lower side resin plate 14 and slightly closer to the center from both ends in the front-rear direction. The insertion holes (not shown) penetrate the lower side resin plate 14 in the thickness direction. Meanwhile, a screw hole (not shown) for screwing the predetermined lower bolt 14a is formed on the outer side surface of the lower earth retaining panel 10. The insertion hole and the screw hole communicate when the lower side resin plate 14 is fitted into the lower fitting recess 10c.

[0035] The insertion hole (not shown) of the lower bolt 14a in the lower side resin plate 14 has a thread insertion section (not shown) into which the threaded portion is inserted but not the head, and a storage locking section (not shown) into which the head is stored and locked. The axial length of the storage locking section (not shown) of the insertion hole is longer than the axial length of the head of the lower bolt 14a. Therefore, when the lower bolt 14a is screwed into the lower earth-retaining panel 10 and locked inside the lower side resin plate 14, the outer tip of the head of the lower bolt 14a does not protrude from the outer surface of the lower side resin plate 14. The method of fixing the lower side resin plate 14 to the lower earth-retaining panel 10 can be set appropriately.

[0036] A lower blade member 13 is fixed to the front end of each lower earth-retaining panel 10. The upper and lower ends of the lower blade member 13 are aligned in the front-to-rear direction with the upper and lower ends of the lower earth-retaining panel 10. The lower blade member 13 has, over its entire length in the up-down direction, a lower blade member outer surface 13A that is parallel to the outer surface of the lower earth-retaining panel 10, and a lower blade member inner inclined surface 13B whose left-right length gradually increases from the front end of the lower blade member outer surface 13A toward the rear.

[0037] The lower blade member 13 and an upper blade member 23 of the upper unit 2, which will be described later, have the role of cutting the side walls of the trench if there is a section narrower than the earth retaining device 100 when the earth retaining device 100 is towed and moved forward during burial work. The side walls of the trench are cut at the intersection line between the lower blade member outer surface 13A and the lower blade member inner inclined surface 13B, which are formed along the vertical direction, and at the intersection line between the upper blade member outer surface 23A and the upper blade member inner inclined surface 23B, which will be described later.

[0038] A lower cutout 13C is formed at the lower end of the lower blade member 13. The lower cutout 13C is formed by a plane that perpendicularly cuts the lower blade member outer surface 13A along a straight line connecting a point that is the front tip of the lower blade member outer surface 13A and a predetermined distance above the lower end of the lower blade member 13, and the rear lower end of the lower blade member outer surface 13A.

[0039] The portion of the lower blade member 13 above the lower cutout 13C is configured so that the cross-sectional shape perpendicular to the up-down direction is constant. This cross-sectional shape is a right triangle with sides of different lengths. The hypotenuse of this right triangle is formed by the lower blade member inner inclined surface 13B, and the longer side is formed by the lower blade member outer surface 13A.

[0040] Three lower claws 13a are provided at the front end of the lower blade member 13. The lower claws 13a are arranged in parallel at approximately equal intervals along the vertical direction. The three lower claws 13a are provided at positions where the upper sides of each pair of two lower rails 10a are extended forward. When the soil retaining device 100 is advanced, the lower claws 13a are inserted into the side wall of the groove before the tip of the lower blade member 13, so that the entire tip of the lower blade member 13 (the intersection between the lower blade member outer surface 13A and the lower blade member inner inclined surface 13B) reliably cuts the side wall of the groove. Therefore, the front half of the lower claws 13a protrudes forward from the tip of the lower blade member 13. On the other hand, the rear half of the lower claws 13a is formed so as to sandwich the lower blade member outer surface 13A and the lower blade member inner inclined surface 13B.

[0041] A connecting jig 13b is provided at a position slightly above the lower cutout portion 13C of each lower blade member inner inclined surface 13B. Both ends of one towing string 16 are connected to each connecting jig 13b via a shackle or the like. The length of the towing string 16 is about 1.5 to 2.0 times the short side direction of the lower retaining panel 10. During burial work, the tip of a backhoe bucket is hooked around the center of the towing string 16, and the backhoe is used to tow the retaining device 100 forward to move the retaining device 100 forward.

[0042] Since the earth retaining device 100 is towed via the towing string 16, the towing string 16 is made of a material and has a structure having a strength at least sufficient to withstand the static frictional force when the earth retaining device 100 is moved forward. In the first embodiment, the towing string 16 is a steel chain made of steel. When the earth retaining device 100 is not being towed, the towing string 16 is hooked at approximately the center in the length direction to a hook-shaped fastener 11c provided on the lower horizontal support 11 on the front side.

[0043] The lower unit 1 has two soil inflow prevention plate members 17. The soil inflow prevention plate members 17 are connected to the rear ends of the lower retaining panels 10 via predetermined mounting fixtures K. The soil inflow prevention plate members 17 connected to the lower retaining panels 10 are formed in a vertically long rectangular shape. The upper and lower ends of the soil inflow prevention plate members 17 connected to the lower retaining panels 10 are aligned in the left-right direction. The thickness of the soil inflow prevention plate members 17 is preferably 3 to 10 mm, and more preferably 5 to 7 mm.

[0044] A gap S of a predetermined length is formed between the soil inflow prevention plate-like members 17. As described above, the lower horizontal support 11 is configured so that its left-right length can be adjusted, but even when the left-right length of the lower horizontal support 11 is at its minimum, a gap S of a predetermined length is formed between the soil inflow prevention plate-like members 17. In other words, the short-side length of the soil inflow prevention plate-like members 17 is shorter than half the left-right distance when the lower retaining panels 10 are closest to each other.

[0045] In addition, basically, inside the soil retaining device 100, the buried pipe is arranged along the front-rear direction at approximately the center in the left-right direction. The diameter of the buried pipe to be buried is larger than the gap between the soil inflow prevention plate members 17. Therefore, the soil inflow prevention plate member 17 and the buried pipe interfere with each other. Therefore, the soil inflow prevention plate member 17 is made of a material having flexibility such that the inner end can bend backward while the inner end is in contact with the surface of the buried pipe with the outer end restrained in a plan view. On the other hand, the soil inflow prevention plate member 17 has a role of preventing soil backfilled at the rear side from flowing into the soil retaining device 100. Therefore, the material constituting the soil inflow prevention plate member 17 needs to have a certain hardness or more. For example, when the soil inflow prevention plate member 17 is made of elastic rubber (polymeric compound having elasticity) such as natural rubber or synthetic rubber, the hardness of the elastic rubber is preferably 10 to 100.

[0046] The lower unit 1 has ten lower bottom resin plates 18. The lower bottom resin plates 18 are formed in a horizontally elongated rectangular shape. The thickness and short-side length of the lower bottom resin plate 18 are approximately the same as those of the lower side resin plate 14. The long-side length of the lower bottom resin plate 18 is shorter than that of the lower side resin plate 14.

[0047] Five lower bottom resin plates 18 are arranged side by side at equal intervals along the front-to-rear direction on the bottom surface of each lower retaining panel 10. Each lower bottom resin plate 18 is bonded to the bottom surface of the lower retaining panel 10 over the entire side surface on one side. Similarly to the lower side surface resin plate 14, the lower bottom resin plate 18 is detachably fixed to the lower retaining panel 10 at two points along the front-to-rear direction by predetermined lower bolts 18c.

[0048] In addition, the lower bottom resin plate 18 has a role of reducing the frictional force between the side wall (soil) of the excavated trench, compared to when the entire bottom surface of the lower retaining panel 10 contacts the side wall of the trench when the retaining device 100 is towed and advanced in the burial work. Therefore, the lower bottom resin plate 18 is made of a material having a lower static friction coefficient and dynamic friction coefficient with the soil than the lower retaining panel 10. Furthermore, in the first embodiment, the lower bottom resin plate 18 is made of a material having high wear resistance. In the first embodiment, the lower bottom resin plate 18 is made of the same material as the lower side resin plate 14, specifically, ultra-high molecular weight polyethylene (UHMW-PE). However, the material of the lower bottom resin plate 18 may be appropriately set within a range that satisfies the conditions that the static friction coefficient and dynamic friction coefficient with the soil are lower than those of the lower retaining panel 10 and that the wear resistance is high. In addition, the lower bottom resin plate 18 may be made of a single material, or may be made of a compound or mixture of multiple materials. Furthermore, the lower bottom resin plate 18 and the lower side resin plate 14 may be made of different materials.

[0049] The lower unit 1 has six positioning protrusions 19. The positioning protrusions 19 serve to prevent relative left-right misalignment between the lower unit 1 and the upper unit 2. On the upper surface of the lower retaining panel 10, three positioning protrusions 19 are arranged side by side at equal intervals along the front-to-rear direction. The positioning protrusions 19 are formed extending in the front-to-rear direction. The cross-sectional shape of the positioning protrusions 19 perpendicular to the front-to-rear direction is constant. This cross-sectional shape is a V-shape with an upwardly convex V-shape.

[0050] Next, the upper unit 2 will be described. The upper unit 2 has an upper earth retaining panel 20, an upper horizontal support 21, an upper blade member 23, an upper side resin plate 24, and a positioning recess 29. In terms of roles, functions, and uses, the upper earth retaining panel 20, the upper horizontal support 21, the upper blade member 23, and the upper side resin plate 24 correspond to the lower earth retaining panel 10, the lower horizontal support 11, the lower blade member 13, and the lower side resin plate 14.

[0051] The upper unit 2 has two upper retaining panels 20. The upper retaining panels 20 are formed in a horizontally elongated rectangular shape. The long side length of the upper retaining panels 20 is approximately the same as the long side length of the lower retaining panels 10. The short side length of the upper retaining panels 20 is shorter than the short side length of the lower retaining panels 10.

[0052] The two upper retaining panels 20 are fixed by the upper horizontal support 21 with one side flat surfaces facing each other at a predetermined distance. Therefore, a space is formed between the two fixed upper retaining panels 20. This space forms part (the upper side) of the work area W where workers can perform work related to laying the buried pipes. The distance between the upper retaining panels 20 and the distance between the lower retaining panels 10 are approximately the same.

[0053] The long sides and short sides of the two fixed upper retaining panels 20 are parallel to each other. Furthermore, the front ends, rear ends, upper ends, and lower ends of the two fixed upper retaining panels 20 are aligned in the left-right direction.

[0054] The upper retaining panel 20 plays a role of retaining soil against the side wall of the excavated trench when in use (during burial work). Therefore, the upper retaining panel 20 is made of steel material that is given a bending stress corresponding to the required earth pressure. In the first embodiment, the material of the upper retaining panel 20 and the material of the lower retaining panel 10 are the same.

[0055] Moreover, a pair of two upper rail portions 20a extending long in the front-to-rear direction are arranged parallel to each other at a predetermined distance in the vertical direction slightly upward from approximately the vertical center of the upper retaining panel 20. Similarly, a pair of two upper rail portions 20a extending long in the front-to-rear direction are arranged parallel to each other at a predetermined distance in the vertical direction slightly downward from approximately the vertical center of the upper retaining panel 20.

[0056] The vertical separation distance between the pair of two upper rail portions 20a is substantially the same as the vertical separation distance between the pair of two lower rail portions 10a. The front and rear ends of each pair of two upper rail portions 20a are aligned with the front and rear ends of each pair of two lower rail portions 10a in the vertical direction.

[0057] Furthermore, the vertical separation distance between the lower side of a pair of two upper rail portions 20a arranged relatively higher and the upper side of a pair of two upper rail portions 20a arranged relatively lower is approximately the same as the vertical separation distance between the lower side of a pair of two lower rail portions 10a arranged relatively higher and the upper side of two lower rail portions 10a arranged relatively in the middle.

[0058] The cross-sectional shape of the upper rail portion 20a perpendicular to the front-rear direction (extension direction) is constant along the front-rear direction and is substantially the same as the cross-sectional shape of the lower rail portion 10a perpendicular to the front-rear direction (extension direction).

[0059] Between each pair of two upper rail portions 20a, five upper partition portions 20b are arranged at equal intervals along the front-rear direction. The upper partition portion 20b arranged most forward among the five upper partition portions 20b is arranged at the front end of the upper rail portion 20a, and the upper partition portion 20b arranged most rearward among the five upper partition portions 20b is arranged at the rear end of the upper rail portion 20a. The interval between adjacent ones of the five upper partition portions 20b in the front-rear direction is approximately the same as the interval between adjacent ones of the lower partition portions 10b in the front-rear direction, and approximately corresponds to the length of the long side of the upper side resin plate 24 described later.

[0060] The upper partition 20b is formed from the upper rail 20a arranged on the upper side to the upper rail 20a arranged on the lower side. The cross-sectional shape of the upper partition 20b perpendicular to the vertical direction is constant along the vertical direction. The cross-sectional shape is substantially the same as the cross-sectional shape of the lower partition 10b perpendicular to the vertical direction.

[0061] Furthermore, the left-right length of the upper rail portion 20a (the length from the outer surface of the upper earth-retaining panel 20 to the outer tip of the upper rail portion 20a) and the left-right length of the upper partition portion 20b (the length from the outer surface of the upper earth-retaining panel 20 to the outer tip of the upper partition portion 20b) are approximately identical.

[0062] The space formed by each pair of two upper rail portions 20a, each pair of two upper partition portions 20b adjacent in the front-to-rear direction, and the outer surface of the upper earth-retaining panel 20 constitutes an upper fitting recess 20c into which the upper side resin plate 24 fits. Therefore, five upper fitting recesses 20c are arranged in the front-to-rear direction slightly above and slightly below the approximate center in the vertical direction of the outer surface of the upper earth-retaining panel 20.

[0063] The upper unit 2 has one upper horizontal support 21. The upper horizontal support 21 is fixed to the inner surfaces of both upper earth retaining panels 20. Therefore, the distance between the two upper earth retaining panels 20 is maintained by the left-right length of the upper horizontal support 21. The left-right length of the upper horizontal support 21 is approximately the same as the left-right length of the lower horizontal support 11.

[0064] The upper horizontal support 21, like the lower horizontal support 11, has the role of preventing the upper earth-retaining panel 20 from collapsing inward when earth pressure acts on the upper earth-retaining panel 20. For this reason, the upper horizontal support 21 is made of steel material that is given an axial force (compressive strength) along the left-right direction that corresponds to the required earth pressure. In addition, the upper horizontal support 21 is configured so that its overall length along the left-right direction can be adjusted.

[0065] The specific structure of the upper horizontal support 21 can be appropriately set within a range capable of withstanding the axial force (compressive strength) along the left-right direction corresponding to the required earth pressure, and the upper horizontal support 21 has two horizontal columnar parts 21a arranged at a predetermined distance in the vertical direction and two vertical columnar parts 21b connecting the two horizontal columnar parts 21a. Also, the material of the upper horizontal support 21 can be appropriately set as long as it is given the axial force (compressive strength) along the left-right direction corresponding to the required earth pressure.

[0066] The upper unit 2 has ten upper side resin plates 24. The upper side resin plates 24 are formed in a horizontally elongated rectangular shape that is approximately the same as the upper fitting recess 20c when viewed from the left-right direction. The upper side resin plates 24 are fitted into the upper fitting recess 20c formed on the outer surface of the upper earth-retaining panel 20. Therefore, the five upper side resin plates 24 are arranged in parallel along the long side direction of the upper earth-retaining panel 20, slightly upward from approximately the center in the vertical direction and slightly downward from approximately the center in the vertical direction.

[0067] The long side length, short side length and thickness of the upper side resin plate 24 are approximately the same as the long side length, short side length and thickness of the lower side resin plate 14. Similarly to the lower side resin plate 14, the upper side resin plate 24 protrudes slightly outward in the left-right direction beyond the tips of the upper rail portion 20a and the upper partition portion 20b.

[0068] The upper side resin plate 24, like the lower side resin plate 14, has a role of reducing the frictional force between the upper side resin plate 24 and the side wall (soil) of the excavated trench, compared to the case where the entire outer surface of the upper retaining panel 20 comes into contact with the side wall of the trench when the retaining device 100 is towed and advanced in the burial work. In the first embodiment, the material of the upper side resin plate 24 is the same as the material of the lower side resin plate 14.

[0069] Furthermore, the upper side resin plate 24 is configured to be detachable from the upper retaining panel 20, similar to the lower side resin plate 14. That is, the upper side resin plate 24 is configured to be detachable from the upper retaining panel 20 by a predetermined upper bolt 24a.

[0070] An upper blade member 23 is fixed to the front tip of each upper earth-retaining panel 20. The upper and lower ends of the upper blade member 23 are aligned in the front-rear direction with the upper and lower ends of the upper earth-retaining panel 20. The upper blade member 23 has, over its entire length in the up-down direction, an upper blade member outer surface 23A that is parallel to the outer surface of the upper earth-retaining panel 20, and an upper blade member inner inclined surface 23B whose left-right length gradually increases from the front tip of the upper blade member outer surface 23A toward the rear.

[0071] The upper blade member 23, together with the lower blade member 13 of the lower unit 1, has the role of cutting the sidewall of the trench if there is a location narrower than the earth retaining device 100 when the earth retaining device 100 is towed and advanced during burial work. The sidewall of the trench is cut at the intersection of the lower blade member outer side surface 13A and the lower blade member inner inclined surface 13B formed along the vertical direction, and at the intersection of the upper blade member outer side surface 23A and the upper blade member inner inclined surface 23B described later.

[0072] The cross-sectional shape of the upper blade member 23 perpendicular to the up-down direction is constant along the up-down direction. This cross-sectional shape is the same as the cross-sectional shape of the lower blade member 13 perpendicular to the up-down direction in the portion above the lower cutout 13C. Therefore, the shape of the upper blade member outer surface 23A and the shape of the upper blade member inner inclined surface 23B are the same as the shape of the lower blade member outer surface 13A and the shape of the lower blade member inner inclined surface 13B in the portion above the lower cutout 13C. Furthermore, the angle between the upper blade member outer surface 23A and the upper blade member inner inclined surface 23B in a plan view is the same as the angle between the lower blade member outer surface 13A and the lower blade member inner inclined surface 13B in the portion above the lower cutout 13C. That is, the intersection of the lower blade member outer surface 13A and the lower blade member inner inclined surface 13B and the intersection of the upper blade member outer surface 23A and the upper blade member inner inclined surface 23B are formed on the same straight line extending in the vertical direction.

[0073] In addition, two upper claws 23a are provided at the front end of the upper blade member 23. The two upper claws 23a are provided at positions where the upper sides of each pair of two upper rails 20a are extended forward. Like the lower claw 13a, the upper claw 23a has a role of cutting the side wall of the groove reliably with the entire tip of the upper blade member 23 (the intersection of the upper blade member outer surface 23A and the upper blade member inner inclined surface 23B) by piercing the side wall of the groove before the tip of the upper blade member 23 when the soil retaining device 100 is advanced. The structure including the shape of the upper claw 23a is the same as the structure including the shape of the lower claw 13a.

[0074] Furthermore, a positioning recess 29 that fits into the positioning protrusion 19 is formed along the front-to-rear direction on the lower end surface of each upper retaining panel 20. The front and rear ends of the positioning recess 29 are aligned with the front and rear ends of the upper retaining panel 20. A concave V-shape that fits into the convex V-shape of the positioning protrusion 19 is formed along the front-to-rear direction on the bottom surface of the positioning recess 29.

[0075] Next, the positional relationship between the outer surface of the lower retaining panel 10, the outer surface of the lower side resin plate 14, and the outer surface of the lower blade member 13A will be described. Fig. 9 is a partially enlarged view showing a schematic plan view of the vicinity of the connection between the lower retaining panel 10 on the right side and the lower blade member 13.

[0076] As shown in FIG. 9, the lower side resin plate 14 protrudes slightly outward from the lower rail portion 10a and the lower partition portion 10b in the left-right direction. In a plan view, the outer surface of the lower side resin plate 14 and the outer surface of the lower blade member 13A are aligned on the same straight line. In other words, the outer surface of the lower blade member 13A and the outer surface of the lower side resin plate 14 are included in the same plane with the front-rear direction and the up-down direction as two axes. The outer surface of the lower side resin plate 14 and the outer surface of the lower blade member 13A are formed outward in the left-right direction from the outer surface of the lower earth-retaining panel 10 by the thickness of the lower side resin plate 14. In other words, a step D by the thickness of the lower side resin plate 14 is formed between the lower earth-retaining panel 10 and the lower blade member 13. In practice, the outer surface of the lower blade member 13A and the outer surface of the lower side resin plate 14 are formed on the outermost side in the left-right direction in the entire earth-retaining device 100.

[0077] As described above, the lower blade member 13 has a role of cutting the side wall of the trench when there is a location narrower than the earth retaining device 100 when the earth retaining device 100 is towed and advanced in burial work. In the entire earth retaining device 100, the lower blade member outer surface 13A and the outer surface of the lower side resin plate 14 are formed on the outermost side in the left-right direction. Therefore, when the earth retaining device 100 advances, the side wall of the trench is cut at the intersection of the lower blade member outer surface 13A and the lower blade member inner inclined surface 13B formed along the up-down direction, while the lower side resin plate 14 formed behind the lower blade member outer surface 13A along the front-rear direction slides on the cut side wall of the trench.

[0078] In addition, in Figure 9, the dotted line drawn between the lower blade member 13 and the lower side resin plate 14 is an auxiliary line indicating that the outer surface of the lower side resin plate 14 and the outer surface 13A of the lower blade member are aligned in the same straight line, and is not actually shown.

[0079] 9 shows a schematic plan view of the connection between the lower blade member 13 and the right-side lower earth-retaining panel 10, but the positional relationship between the lower blade member outer surface 13A, the outer surface of the lower side resin plate 14, and the outer surface of the lower earth-retaining panel 10 described with reference to FIG. 9 is the same for the left-side lower earth-retaining panel 10. Furthermore, the same is true for both upper earth-retaining panels 20 of the upper unit 2.

[0080] Next, a description will be given of an embedding method using the earth retaining device 100. In the embedding method, first, an earth retaining device sinking step is performed, then an embedded pipe laying step is performed, and finally, an earth retaining device removal step is performed.

[0081] First, the earth retaining device installation process will be described. In the earth retaining device installation process, first, a trench (installation trench) for the earth retaining device 100 is excavated. Next, the lower unit 1 is installed in the installation trench using a specified heavy machine such as a backhoe. Next, the upper unit 2 is placed on the lower unit 1. Furthermore, the lower unit 1 and the upper unit 2 are fixed to each other and integrated by a specified fixing structure. Finally, in the earth retaining device installation process, the inside of the earth retaining device 100 is excavated to a desired depth (depth at which the buried pipe is laid), and the earth retaining device 100 is installed.

[0082] It is desirable that the shape and dimensions of the installation groove are as small as possible, as long as the retaining device 100 can be installed in the installation groove. Therefore, when the retaining device installation process is completed, there is almost no gap between the left and right side surfaces of the retaining device 100 (the outer surfaces of the lower side resin plate 14 and the upper side resin plate 24, the outer surface 13A of the lower blade member, and the outer surface 23A of the upper blade member) and the rear end of the retaining device 100 and the side walls of the installation groove facing them. For example, the dimensions of the installation groove are 4.0 m in the front-rear direction, 1.1 m in the left-right direction, and 1.5 m in depth.

[0083] Next, the earth retaining device removal process will be described. In the earth retaining device removal process, first, sand is filled into a part of the inside of the earth retaining device 100. Next, the front and rear sides of the earth retaining device 100 are alternately pulled up and raised. Furthermore, the lower unit 1 and the upper unit 2 are released from their fixed position. Finally, in the earth retaining device removal process, sand is sequentially filled into the inside of the earth retaining device 100 while the upper unit 2 and the lower unit 1 are pulled out.

[0084] Next, the buried pipe laying process will be described. A buried pipe laying cycle process including a plurality of processes each consisting of a unit smaller than the retaining device sinking process and the retaining device removal process is repeated a plurality of times. FIG. 10 is a flowchart of the buried pipe laying cycle process. As shown in FIG. 10, the buried pipe laying cycle process includes a piping process, a pre-digging and refilling process, a towing preparation process, and a towing and backfilling process.

[0085] In the piping process, buried pipes to be buried by the burial method, such as power cable protection pipes, are placed on the bottom of the trench inside the earth retaining device 100. In the first buried pipe laying cycle process, in other words, the buried pipe laying cycle process immediately after the earth retaining device sinking process, the piping process ends when the buried object is placed. On the other hand, in the second or subsequent buried pipe laying cycle processes, the buried object is placed first, and then the buried pipe installed in the previous buried pipe laying cycle process is connected to the buried pipe that has been placed.

[0086] In the pre-excavation and refilling process, the front side of the earth retaining device 100 is pre-excavated by the length in the front-rear direction of the buried pipe to be placed next. Here, in the case of the second or subsequent buried pipe laying cycle process, as described below, a space is formed at the rear side of the earth retaining device 100 by the amount of the forward movement of the earth retaining device 100 in the towing and backfilling process in the previous buried pipe laying cycle process, so in the pre-excavation and refilling process, river sand is further refilled into this space to the extent that it does not flow into the earth retaining device 100. The "extent that does not flow into the earth retaining device 100" means at least the extent that the vertical height of the river sand at the rear end of the earth retaining device 100 does not exceed the vertical height position of the soil inflow prevention plate-like member 17.

[0087] In the towing preparation step, a worker inside the earth retaining device 100 removes the towing string 16 hooked to the fastener 11c while remaining inside, and throws the entire towing string 16 to the front side of the earth retaining device 100, preferably so that the approximate center in the length direction of the towing string 16 is positioned at the frontmost position. Next, the backhoe operator operates the towing string 16 that has been thrown to the front side of the earth retaining device 100 and placed on the ground, and hooks it directly with the tip of the backhoe bucket.

[0088] In the towing and backfilling process, the retaining device 100 is towed forward by a backhoe connected to the retaining device 100 via the towing string-like body 16, and the retaining device 100 is advanced. At the same time, the river sand for backfilling is replenished at the rear side of the retaining device 100, and the river sand backfilled at the rear of the retaining device 100 is appropriately compacted by the backhoe arranged at the rear side. After the towing of the towing string-like body 16 is completed, for example, the backhoe operator moves the bucket to remove the bucket from the towing string-like body 16. Furthermore, the backhoe operator pushes the towing string-like body 16 arranged at the front side of the retaining device 100 into the inside of the retaining device 100 with the tip of the bucket or the like. Then, a worker inside the retaining device 100 hooks the towing string-like body 16 to the fastener 11c. When such a towing and backfilling process is completed, one buried pipe laying cycle process is completed, and the buried pipe laying cycle process is repeated until the planned buried pipe is completed. When the planned buried object is completed, the retaining device removal process is performed. Note that FIG. 11 is a specific example showing a state in which the retaining device 100 has been towed at least once and the buried pipe M is in contact with the inner surfaces of both soil inflow prevention plate-like members 17. Also, FIG. 12 is a specific example showing a state in which the retaining device 100 is towed by a backhoe via the towing string-like body 16 after a new buried pipe M2 is connected to the existing buried pipe M1 inside the retaining device 100.

[0089] As described above, the earth-retaining device 100 includes a pair of earth-retaining panels (lower earth-retaining panel 10, upper earth-retaining panel 20) that are held facing each other at a predetermined distance and form a working area W, blade members (lower blade member 13, upper blade member 23) provided on the front side along the movement direction of each of the pair of earth-retaining panels, and plates (lower side resin plate 14, upper side resin plate 24) installed on a portion of the outer surface of each of the pair of earth-retaining panels, and the coefficient of friction between the outer surfaces of the plates (lower side resin plate 14, upper side resin plate 24) and the soil is 1 / 1000 of the outer surfaces of the earth-retaining panels (lower earth-retaining panel 10, upper earth-retaining panel 20). The coefficient of friction between the blade members (lower blade member 13, upper blade member 23) is lower than the coefficient of friction between the blade members and the soil, and outer surfaces (lower blade member outer surface 13A, upper blade member outer surface 23A) are formed on the same plane as the outer surfaces of the plates (lower side resin plate 14, upper side resin plate 24), and the outer surfaces of the blade members (lower blade member outer surface 13A, upper blade member outer surface 23A) and the outer surfaces of the plates (lower side resin plate 14, upper side resin plate 24) are formed outward in the direction in which the pair of earth-retaining panels (lower earth-retaining panel 10, upper earth-retaining panel 20) face each other. Therefore, compared to when the entire outer surface of the retaining panels (lower retaining panel 10, upper retaining panel 20) comes into contact with the side wall of the trench when the retaining device 100 is towed forward during burial work, the frictional force between the retaining panels and the side wall (soil) of the excavated trench is reduced, and hindrance to forward movement is reduced.

[0090] In addition, according to the earth retaining device 100, a plate-shaped member (earth and sand inflow prevention plate-shaped member 17) having flexibility to at least bend is provided at a predetermined distance in the direction in which the pair of earth retaining panels face each other at the rear end along the movement direction of each of the pair of earth retaining panels. Therefore, it is possible to prevent the inflow of earth into the earth retaining device 100 due to backfilling, while preventing damage to and displacement of the buried pipe due to contact between the plate-shaped member (earth and sand inflow prevention plate-shaped member 17) and the buried pipe, especially when moving (pulling) forward. Furthermore, according to the earth retaining device 100, a string-shaped body (pulling string-shaped body 16) for towing the earth retaining device 100 is connected across each of the front end portions of the blade members, and the string-shaped body has a weight that allows it to be thrown forward as a whole. Therefore, it is possible to improve the safety of the workers inside the earth retaining device 100 when connecting the earth retaining device 100 to a backhoe.

[0091] In addition, according to the burial method using the earth retaining device 100, the frictional force between the side wall (soil) of the excavated trench is reduced by the moving process (towing and backfilling process) compared to the case where the entire outer surface of the earth retaining panel (lower earth retaining panel 10, upper earth retaining panel 20) contacts the side wall of the trench when the earth retaining device 100 is towed and moved forward in the burial work, so that the hindrance to the forward movement can be suppressed. In other words, the workability is improved. Furthermore, the towing preparation process allows the earth retaining device 100 and the backhoe to be connected while the worker is staying inside the earth retaining device 100, so that the safety for the worker inside the earth retaining device 100 can be improved.

[0092] <Example of change> Next, modified examples of the earth retaining device 100 according to the first embodiment will be described. The above-described embodiment can be modified as appropriate without departing from the gist of the present invention. For example, the shape of the earth retaining device 100 is generally rectangular parallelepiped, but the ratio of the front-rear length, left-right length, and up-down length of the rectangular parallelepiped is not particularly limited and may be modified as appropriate. However, since the earth retaining device 100 is used in burying work at a depth where soil retention is required, it is preferable that the front-rear length > up-down length > left-right length.

[0093] The earth retaining device 100 is configured so as to be assembled from a lower unit 1 and an upper unit 2, but may be configured so as to be inseparably integrated. The earth retaining device 100 may also be configured so as to be assembled from three or more units in the vertical direction. Alternatively, the earth retaining device 100 may be configured so as to be assembled from two or more units in the front-rear direction.

[0094] The lower retaining panel 10 has five lower side resin plates 14 arranged in the front-rear direction at three locations in the vertical direction, but the locations and the number of plates in the vertical direction, as well as the number of plates in the front-rear direction, may be changed as appropriate. The same applies to the upper side resin plates 24.

[0095] The lower retaining panel 10 has five lower side resin plates 14 arranged in the front-rear direction at three locations in the vertical direction, but the number of lower side resin plates 14 arranged in the front-rear direction may be different depending on the location in the vertical direction. In addition, the lower retaining panel 10 has lower side resin plates 14 arranged in the front-rear direction with the same front-rear length (long side length) at three locations in the vertical direction, but the front-rear length (long side length) of the lower side resin plates 14 may be different depending on the location in the vertical direction. Furthermore, the lower retaining panel 10 has lower side resin plates 14 arranged in the front-rear direction with the same front-rear length (short side length) at three locations in the vertical direction, but the vertical length (short side length) of the lower side resin plates 14 may be different depending on the location in the vertical direction. The number of lower side resin plates 14 arranged side by side in the front-to-back direction, the vertical length (short side length) of the lower side resin plates 14, and examples of changes to the vertical length (short side length) of the lower side resin plates 14 also apply to the upper side resin plates 24.

[0096] The lower side resin plates 14 having the same front-rear length (long side length) are arranged in the front-rear direction at three positions in the vertical direction in the lower retaining panel 10, but the front-rear length (long side length) of the lower side resin plates 14 may be different depending on the installation positions in the front-rear direction. For example, the front-rear length (long side length) of the lower side resin plates 14 may be longer from the front side to the rear side. Alternatively, the front-rear length (long side length) of the lower side resin plates 14 may be shorter from the front side to the rear side. Furthermore, the front-rear length (long side length) of the lower side resin plates 14 arranged at both ends in the front-rear direction and the other lower side resin plates 14 may be different from each other. The same applies to the upper side resin plate 24 for the change examples of the front-rear length (long side length) of the lower side resin plates 14.

[0097] The left-right length of the lower side resin plate 14 is longer than the left-right length of the lower rail portion 10a and the left-right length of the lower partition portion 10b, and the lower side resin plate 14 protrudes outward from the lower rail portion 10a and the lower partition portion 10b in the left-right direction, in other words, the outer surface of the lower side resin plate 14 is formed outward from the outer tips of the lower rail portion 10a and the lower partition portion 10b, but may be formed at approximately the same position as the outer tips of either or both of the lower rail portion 10a and the lower partition portion 10b, or may be formed inward from the outer tips. The same applies to the upper side resin plate 24, the upper rail portion 20a, and the upper partition portion 20b with respect to the modification example of the positional relationship in the left-right direction between the lower side resin plate 14, the lower rail portion 10a, and the lower partition portion 10b.

[0098] The distance between the lower side of the pair of lower rail parts 10a arranged relatively on the upper side and the upper side of the pair of lower rail parts 10a arranged relatively in the center, and the distance between the upper side of the pair of lower rail parts 10a arranged relatively in the center and the lower side of the pair of lower rail parts 10a arranged relatively on the lower side are approximately the same, but may be different. The distance between the lower side of the pair of lower rail parts 10a arranged relatively on the upper side and the upper side of the pair of lower rail parts 10a arranged relatively in the center, and the distance between the lower side of the pair of upper rail parts 20a arranged relatively on the upper side and the upper side of the pair of upper rail parts 20a arranged relatively on the lower side are approximately the same, but may be different.

[0099] A pair of sediment inflow prevention plate members 17 are installed at the rear end of the lower unit 1, but the sediment inflow prevention plate members 17 do not have to be installed. However, from the viewpoint of the effect of improving the quality of the buried object by preventing the inflow of sediment into the soil retaining device 100, it is preferable to install the sediment inflow prevention plate members 17.

[0100] A gap is formed between the pair of sediment inflow prevention plate members 17, but the left-right length of this gap may be changed as appropriate. Also, no gap may be formed between the pair of sediment inflow prevention plate members 17. However, from the viewpoint of the effect of improving the quality of buried objects by reducing contact with the buried objects, it is preferable that a gap is formed between the pair of sediment inflow prevention plate members 17.

[0101] A lower bottom resin plate 18 is installed on the bottom surface of each lower retaining panel 10, but the lower bottom resin plate 18 does not have to be installed. However, from the viewpoint of the effect of reducing the frictional force with the soil when the retaining device 100 is towed, it is preferable to install the lower bottom resin plate 18.

[0102] A towing string 16 is connected to the lower end of the lower blade member 13. The structure of the towing string 16 may be modified as appropriate as long as it has a cutting load that can withstand the load when the earth retaining device 100 is towed, a length for connecting to a backhoe, and can be thrown forward of the earth retaining device 100 and hooked to the tip of the backhoe bucket at its approximate middle part. For example, the towing string 16 may be composed of a straight or bow-type hoisting fitting and two wire ropes connected to the hoisting fittings via thimbles or the like. In this case, even if the wire rope does not have a weight that can be thrown forward of the earth retaining device 100, the hoisting fittings that constitute the towing string 16 can be thrown forward of the earth retaining device 100.

[0103] The three lower claws 13a are provided at positions where the upper sides of the two lower rail parts 10a of each pair are extended forward as they are, but the positions along the vertical direction may be changed as appropriate. For example, the three lower claws 13a may be provided at positions where the lower sides of the two lower rail parts 10a of each pair are extended forward as they are. Alternatively, the three lower claws 13a may be provided at positions where the approximate centers of the two lower rail parts 10a of each pair are extended forward as they are. That is, the three lower claws 13a may be provided as appropriate within a range where the range of the two lower rail parts 10a of each pair is extended forward as they are. The same modification example of the relationship between the positions along the vertical direction of the three lower claws 13a and the positions along the vertical direction of the two lower rail parts 10a of each pair is also applicable to the relationship between the positions along the vertical direction of the two upper claws 23a and the positions along the vertical direction of the two lower rail parts 10a of each pair.

[0104] The lower horizontal support 11 and the upper horizontal support 21 are configured so that their left-right lengths can be adjusted, but the left-right lengths may be fixed. The retaining device 100 is configured so that it can be moved by heavy machinery such as a backhoe, but it may also have its own propulsion means so that it can move within the trench by itself. [Explanation of symbols]

[0105] 1...Lower unit 2. Upper unit 10…Lower retaining panel 10a…Lower rail section 10b…Lower partition 10c…Lower fitting recess 11...Lower horizontal support 13...Lower cutting member 13a...Lower claw part 13b...Connecting jig 13A…Outer surface of lower blade member 13B…Inner slope of lower blade member 13C…Lower cutout 14…Lower side resin plate 14a…Lower bolt 15…Lower hanging bracket 16...Traction strap 17...Sediment inflow prevention plate-shaped member 18…Lower bottom resin plate 2. Upper unit 20…Upper retaining panel 20a…Upper rail section 20b...Upper partition 20c…Upper mating recess 21...Upper horizontal support 23...Upper cutting member 23a…Lower claw part 23A: Outer surface of upper blade member 23B…Inner slope of upper blade member 24…Upper side resin plate 24a…Upper bolt 100...Mobile earth retaining device

Claims

1. A mobile earth retaining device having a working area formed inside for laying buried pipes while moving an excavated trench in the excavation direction, A pair of retaining panels that are held facing each other at a predetermined distance and form the working area; A blade member provided on a front side of each of the pair of earth retaining panels along the movement direction; a plate installed on a portion of each of the outer surfaces of the pair of earth retaining panels; The coefficient of friction between the outer surface of the plate and the soil is lower than the coefficient of friction between the outer surface of the retaining panel and the soil, The blade member is formed with an outer surface that is included in the same plane as the outer surface of the plate, A mobile soil-retaining device characterized in that the outer surfaces of the blade member and the outer surfaces of the plate are formed outwardly of the outer surfaces of the soil-retaining panels in the direction in which the pair of soil-retaining panels face each other.

2. The mobile soil retaining device according to claim 1, A mobile earth retaining device characterized in that a plate-shaped member having at least a degree of flexibility capable of bending is provided at the rear end of each of the pair of earth retaining panels in the direction of movement, at a predetermined distance in the direction in which the pair of earth retaining panels face each other.

3. The mobile earth retaining device according to claim 1 or 2, A mobile earth retaining device characterized in that a string-like body for towing the mobile earth retaining device is connected across each of the front ends of the blade members, and the string-like body as a whole has a weight sufficient to allow it to be thrown forward.

4. A method for embedding a soil using the mobile soil retaining device according to claim 1, A piping process of laying a buried pipe in the working area formed inside the mobile earth retaining device installed in the trench; After the piping process, a pre-digging process of excavating a front side of the mobile earth retaining device; This burial method includes a moving step, which is performed after the pre-excavation step, of moving the mobile earth retaining device forward within the trench using an external driving means or an internal propulsion means.

5. A method for embedding a pile using the mobile earth retaining device according to claim 3, A piping process of laying a buried pipe in the working area formed inside the mobile earth retaining device installed in the trench; After the piping process, a pre-digging process of excavating a front side of the mobile earth retaining device; A towing preparation process for throwing the string-like body in front of the mobile earth retaining device after the pre-digging process; This burial method includes a towing step, which is performed after the towing preparation step, of connecting the string-like body to an external driving means and towing the mobile earth retaining device so as to move it forward within the trench using the external driving means.

Images