JP2017145595A - End structure of preceding element and construction method of continuous underground wall - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an end structure of a preceding element and a construction method of a continuous underground wall in which the continuous underground wall with water-stopping properties and cross section force transmission performance is made possible to be constructed simply and at low cost.SOLUTION: An end structure 1B of a preceding element includes a partition plate 11 disposed in the boundary between a preceding element 1 and a succeeding element 2, a connecting member 12 projected to the side face of the succeeding element 2 side of the partition plate 11, and a space forming member 15 for forming a space around the connecting member 12. The space forming member 15 has a shape holding part 152 attached to the tip of the connecting member 12, and a cover part 151 for covering the connecting member 12 and the shape holding part 152. At least the cover part 151 can be cut by a ground excavator.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an end portion structure of a leading element of an underground continuous wall and a method for constructing the underground continuous wall.

The underground continuous wall is generally constructed by dividing it into a plurality of elements.
The underground underground wall is generally used as a retaining wall (temporary structure) when constructing an underground structure. However, in recent years, for the purpose of rationalizing the structure, there is a demand for an underground continuous wall that can be used as a permanent structure. In addition to water blocking, an improvement in cross-sectional force transmission performance is also required at the joint between the preceding element and the succeeding element in the underground continuous wall.

As a joining structure of elements with cross-sectional force transmission performance, the reinforcing bar of the leading element is projected to the succeeding element side when constructing the leading element, and the continuity of the reinforcing bar between the leading element and the trailing element May be secured to ensure the transmission performance of the cross-sectional force.
In this joint structure, a reaction force material, crushed stone, concrete protective plate, interlocking plate, etc. are interposed for the purpose of protecting and preventing the overhanging part of the reinforcing bar, and it is extracted or removed after the construction of the preceding element. Generally, such work takes time.

Therefore, as shown in Patent Document 1, the present applicants and the like have a partition plate disposed at the boundary between the preceding element and the succeeding element, and an end surface disposed on the succeeding element side with respect to the partition plate. A cover, a spacer interposed between the partition plate and the end surface cover, a connecting member penetrating the partition plate, and stoppers disposed on the preceding element side surface and the succeeding element side surface of the partition plate, respectively. The end structure of the leading element with water plate has been developed and put to practical use. The end surface cover and the spacer are made of a material that can be cut by a ground excavator, and an end portion of the connecting member on the trailing element side is in a space formed between the partition plate and the end surface cover. Has been placed.
According to the end portion structure of the preceding element, the end face cover and the spacer are cut when the succeeding element is constructed to expose the connection member and the water stop plate, thereby entraining the connection member and the water stop plate. Therefore, it is possible to construct a trailing element, and thus it is possible to easily construct an underground continuous wall that ensures water-stopping and cross-sectional force transmission performance.

Japanese Patent Laying-Open No. 2015-175179

The end surface cover provided on the end structure of the preceding element must be capable of being cut and have sufficient strength against the pressure applied by the cast concrete, the stable liquid during excavation, and the like. On the other hand, when the underground continuous wall is used as the main structure, the wall thickness of the underground continuous wall tends to increase. When the wall thickness of the underground continuous wall is increased, the distance between the fulcrums of the end surface cover is increased, and therefore the strength of the end surface cover must be increased.
If the strength of the end face cover is increased, the excavation work at the time of construction of the succeeding element takes time and the material cost becomes high.
From this point of view, the present invention proposes an end structure of the preceding element and a construction method of the underground continuous wall, which makes it possible to easily and inexpensively construct the underground continuous wall having the cross-sectional force transmission performance. The task is to do.

In order to solve the above-mentioned problems, the end portion structure of the preceding element according to the present invention has a partition plate disposed at the boundary between the preceding element and the succeeding element, and a side surface on the succeeding element side of the partition plate. An end portion structure of a preceding element comprising a connecting member provided and a space forming member that forms a space around the connecting member, wherein the space forming member is attached to the tip of the connecting member It has a holding part and a cover part which covers the connection member and the shape holding part, and at least the cover part can be cut with a ground excavator.
The shape holding portion may be a plate material on which a plurality of irregularities are formed or a solid member. The plate material is made of a material that can be cut by a ground excavator or can be deformed when excavated by the ground excavator. The solid member is made of a material that can be cut by a ground excavator.
A protective plate detachably connected to the partition plate may be interposed between the connection member and the space forming member, and the shape holding portion may be brought into contact with the protective plate. If it does in this way, when excavating the excavation groove for succeeding elements, a connection member can be protected.

According to the end portion structure of the preceding element, the cover portion can be cut when constructing the excavation groove for the succeeding element, so that the connecting member is exposed, and thus the succeeding element is constructed with the connecting member being wound. be able to. By doing so, it is possible to easily construct an underground continuous wall that ensures the cross-sectional force transmission performance.
Since the space forming member has the shape holding portion, the distance between the fulcrums of the cover portion does not increase even when the underground continuous wall having a large wall thickness is formed.

  The underground continuous wall construction method of the present invention includes a preceding excavation step for excavating a preceding excavation groove, a preceding formation step for forming an advance element in the preceding excavation groove, and a subsequent excavation continuous with the preceding excavation groove. An underground continuous wall construction method comprising: a subsequent excavation step of excavating a groove; and a subsequent formation step of forming a subsequent element that is continuous with the preceding element in the subsequent excavation groove, wherein the preceding formation step The element frame is assembled with a reinforcing bar rod and a partition plate to form a reinforcing bar unit, and a cover material that can be cut by a ground excavator is installed at the end of the element frame, and is projected from the partition plate. Cover installation work for covering the connecting member with the cover material, construction work for inserting the reinforcing bar unit and the cover material into the preceding excavation groove, and the partition plate and the cover material. An insertion operation for inserting the shape-retaining material into the space, and a placement operation for placing concrete in the preceding excavation groove. In the insertion operation, between the tip of the connection member and the cover material It is characterized in that the shape holding material is interposed.

According to the construction method of the underground continuous wall, it is possible to easily construct the underground continuous wall that ensures the cross-sectional force transmission performance. Moreover, even if it is a case where an underground continuous wall with a large wall thickness is formed by inserting a shape-retaining material, the distance between the fulcrums of the cover material does not increase.
In addition, a joining member can be protected at the time of a subsequent excavation by inserting the support material provided with the protection board with the said shape maintenance material in the said insertion operation | work. In the cover installation operation, the shape holding material may be installed together with the cover material at the end of the element frame, and in the insertion operation, only the support material may be inserted into the space. The support material is extracted from the space in the subsequent formation step.

  According to the end structure of the preceding element and the underground continuous wall construction method of the present invention, the underground continuous wall having the cross-sectional force transmission performance can be easily and inexpensively constructed.

It is a plane sectional view showing a part of underground underground wall of an embodiment of the present invention. It is a cross-sectional view which shows the junction part of a preceding element and a succeeding element. (A) is a flowchart which shows the construction method of the underground continuous wall of this embodiment, (b) is a flowchart which shows each operation | work of a preceding formation process, (c) is a flowchart which shows each operation | work of a subsequent formation process. It is. (A)-(d) is a top view which shows each construction condition of the construction method of the underground continuous wall of embodiment of this invention. It is a plane sectional view showing the end part structure of the preceding element. It is a perspective view which shows a cover material. (A) is a front view which shows the shape holding material of this embodiment, (b) and (c) are front views which show the shape holding material which concerns on another form. (A) And (b) is a plane sectional view showing the shape maintenance material concerning other forms. (A) And (b) is a plane sectional view showing a protection board concerning other forms.

In the present embodiment, as shown in FIG. 1, a case in which an underground continuous wall is constructed by connecting a trailing element 2 next to a preceding element 1 will be described.
The preceding element 1 and the succeeding element 2 are constituted by a concrete bar 3 and a reinforcing bar 4 embedded in the concrete 3, respectively. At the joint between the preceding element 1 and the succeeding element 2, a recess 1A is formed on the preceding element 1 side, and a projection 2A that engages with the recess 1A is formed on the succeeding element 2 side.

On the bottom of the recess 1A (side end surface of the preceding element 1), a partition plate 11 on which a plurality of joining members 12 and a water stop plate 13 are projected is disposed. The joining member 12 penetrates the partition plate 11 and is disposed across the preceding element 1 and the succeeding element 2 (convex portion 2A). In this embodiment, the four joining members 12 are juxtaposed at a predetermined interval in the front-rear direction (the wall thickness direction of the underground continuous wall). Further, as shown in FIG. 2, the joining members 12 are provided in a plurality of stages in parallel at a predetermined interval in the depth direction.
The water stop plate 13 is erected on the preceding element side surface and the succeeding element side surface of the partition plate 11, respectively. In addition, although the material which comprises the water stop board 13 is not limited, In this embodiment, it comprises by welding a steel plate to the partition plate 11. FIG. Further, the water stop plate 13 may be formed by a plate-like member having the partition plate 11 penetrated, or may be fixed to a bracket formed on the partition plate 11. Moreover, what is necessary is just to arrange | position the water stop board 13 as needed.

As shown in FIGS. 1 and 2, a joining bar 21 is arranged on the convex portion 2 </ b> A. In the present embodiment, five joining bars 21 are arranged at the same pitch as the arrangement pitch of the joining members 12 with respect to the front-rear direction of the trailing element 2. The adjacent joining bars 21 and 21 are arranged so as to sandwich the joining member 12. As shown in FIG. 2, the joining bars 21 are formed by bending a reinforcing bar into a U shape, and are arranged at a pitch twice that of the joining member 12 in the depth direction. In addition, the shape of the joining bar | burr 21, a bar arrangement pitch, etc. are not limited.
In the present embodiment, split reinforcing bars 22 that intersect with the joining bars 21 are arranged at positions adjacent to the joining members 12 in the convex portion 2A. In addition, what is necessary is just to arrange the split reinforcement 22 as needed.

The partition plate 11 and the reinforcing bar 4 disposed in the preceding element 1 are assembled to the element frame 14. The partition plate 11, the element frame 14 and the reinforcing bar 4 constitute a reinforcing bar unit 10.
The element frame 14 is formed by combining steel materials. The element frame 14 of the present embodiment is disposed in the inner space of the reinforcing bar 4 and is disposed in a plurality of stages in the height direction.
The element frame 14 includes a cross member 141 disposed on the front side and the rear side (upper side and lower side in FIG. 1), a vertical member 142 that connects the front and rear cross members 141, and a diagonal member 143. Yes. The configuration of the element frame 14 is not limited.

Although the material which comprises the crosspiece 141 is not limited, L-shaped steel is used in this embodiment.
The cross member 141 is disposed along the wall surface of the excavation groove excavated when the preceding element is constructed.
In the present embodiment, the four vertical members 142 are laid between the two horizontal members 141, and thus have a ladder shape in plan view. In addition, although the material which comprises the vertical member 142 is not limited, L-shaped steel is used in this embodiment. In addition, a space (interval) for piping the tremmy pipe P is secured between the adjacent vertical members 142 in the central portion of the element frame 14.
One end of the diagonal member 143 is fixed to the cross member 141, and the other end of the diagonal member 143 is fixed to the partition plate 11 or the vertical member 142 at the end.

On the front surface and the rear surface of the element frame 14, reticulated reinforcing bars (lattice reinforcing bars) 41 formed by combining vertical bars 42 and horizontal bars 43 are arranged. The mesh reinforcing bar 41 is fixed to the front surface and the rear surface of the element frame 14 and forms the reinforcing bar rod 4.
It should be noted that the reinforcing bar diameters, bar arrangement pitches, and the like of the vertical bars 42 and the horizontal bars 43 constituting the reinforcing bar 4 are not limited and may be set as appropriate.

A pair of partition plates 11 are fixed to both end portions (left and right end portions in FIG. 1) of the element frame 14.
The partition plate 11 is a plate material disposed at the boundary between the preceding element 1 and the succeeding element 2, and is fixed to the other ends of the longitudinal member 142 and the diagonal member 143 disposed on the succeeding element 2 side. ing. The partition plate 11 extends in the height direction (the direction perpendicular to the paper surface in FIG. 1).
As shown in FIG. 2, the connecting member 12 includes a shaft portion 121 made of a rod-shaped member, and a head portion 122 formed at both ends of the shaft portion 121 and having a larger width (outer diameter) than the shaft portion 121. It is a so-called stud. The configuration of the connecting member 12 is not limited. For example, the connection member 12 may be configured by deformed reinforcing bars. Moreover, the connection member 12 does not necessarily have to penetrate the partition plate 11, and may be welded to the partition plate 11, for example.

As shown in FIG. 1, the joint bars 21 and the reinforcing bar rods 4 arranged in the trailing element 2 are assembled to the element frame 23. The joining bar 21, the element frame 23 and the reinforcing bar 4 constitute a reinforcing bar unit 20 of the succeeding element 2.
The element frame 23 is formed by combining steel materials. The element frame 23 of the present embodiment is disposed in the inner space of the reinforcing bar 4 and is disposed in a plurality of stages in the height direction.

The element frame 23 includes a cross member 231 disposed on the front side and the rear side (upper side and lower side in FIG. 1), a vertical member 232 connecting the front and rear cross members 231, and a diagonal member 233. Yes. The configuration of the element frame 23 is not limited.
The details of the cross member 231 and the vertical member 232 are the same as those of the cross member 141 and the vertical member 142 of the preceding element 1, and thus detailed description thereof is omitted.
One end of the diagonal member 233 is fixed to the cross member 231, and the other end of the diagonal member 233 is fixed to the vertical member 142.

A mesh-like reinforcing bar (lattice reinforcing bar) 41 formed by combining vertical bars 42 and horizontal bars 43 is arranged on the front and rear surfaces of the element frame 23. The mesh reinforcing bar 41 is fixed to the front surface and the rear surface of the element frame 14 and forms the reinforcing bar rod 4.
It should be noted that the reinforcing bar diameter and the reinforcing bar pitch of the vertical bars and the horizontal bars constituting the reinforcing bar 4 are not limited and may be set as appropriate.
The joining bar 21 is fixed to the vertical member 232 of the element frame 23. In the present embodiment, the joining bars 21 are fixed to the two vertical members 232 in a state of being horizontally mounted on the two vertical members 232.

As shown in FIG. 3A, the underground continuous wall construction method of the present embodiment includes a preceding excavation step S1, a preceding formation step S2, a subsequent excavation step S3, and a subsequent formation step S4. ing.
The preceding excavation step S1 is a step of excavating the preceding excavation groove D1, as shown in FIG.
The preceding excavation groove D1 is excavated by a ground excavator (not shown) such as a trench cutter. In addition, the excavation method of the preceding excavation groove D1 is not limited.

The preceding formation step S2 is a step of forming the preceding element 1 in the preceding excavation groove D1.
As shown in FIG. 3B, the preceding formation step S2 of the present embodiment includes an assembling operation S21, a cover installation operation S22, an erection operation S23, an insertion operation S24, and a placement operation S25. ing.
In the assembling operation S21, the reinforcing bar unit 4 and the partition plate 11 are assembled to the element frame 14 to form the reinforcing bar unit 10. The assembling operation S21 may be performed before the preceding excavation step S1, after the preceding excavation step S1, or in parallel with the preceding excavation step S1.

  In the cover installation operation S22, the cover material 151 is installed at the end of the reinforcing bar unit 10 (see FIG. 5). The cover material 151 is made of a material that can be cut by a ground excavator, and as shown in FIG. 6, a pair of flange portions 151 a and web portions 151 b have a U-shape in a plan view. The cover material 151 extends in the height direction of the element frame 14 and is installed so as to cover the connection member 12 protruding from the partition plate 11. The end of the cover material 151 (a plurality of through holes 151h are formed in the flange portion 151a. The material and shape of the cover material 151 are not limited. It may be.

In the present embodiment, as shown in FIG. 5, the attachment member 16 is fixed to the front edge and the rear edge of the partition plate 11 in advance, and the cover material 151 is fixed to the attachment member 16. In this embodiment, L-shaped steel is fixed to the surface on the subsequent element side of the partition plate 11 as the attachment member 16. The attachment member 16 has one piece fixed to the partition plate 11 and the other piece standing on the partition plate 11. The other piece of the attachment member 16 has a height (length) that does not protrude from the reinforcing bar 4 (lateral bar 43) to the trailing element 2 side. That is, the attachment member 16 is disposed at a position where it does not come into contact with the ground excavator when the end portion of the preceding element 1 is cut during construction of the trailing element 2. In addition, the attachment member 16 may be arrange | positioned continuously in a height direction, and may be arrange | positioned intermittently.
The cover material 151 is attached to the element frame 14 by screwing bolts into the through holes with both ends (both flange portions 151a) attached to the attachment member 16, respectively. In addition, the fixing method of the cover material 151 is not limited. In the cover installation operation S <b> 22, the shape retaining material 152 may be fixed to the element frame 14 together with the cover material 151.
The cover installation operation S22 may be performed before the preceding excavation step S1, after the preceding excavation step S1, or may be performed in parallel with the preceding excavation step S21.

In the erection operation S23, as shown in FIG. 4B, the reinforcing bar unit 10 on which the cover material 151 is installed is inserted into the preceding excavation groove D1.
At this time, a spacer (not shown) is interposed between the reinforcing bar unit 10 and the inner wall surface of the preceding excavation groove D1. The material, shape and arrangement of the spacer are not limited.
When the reinforcing bar unit 10 is installed in the preceding excavation groove D1, the tremy pipe P is piped in the center of the reinforcing bar unit 10 (between the longitudinal members 142 on the center side). The tremy pipe P is inserted until it reaches the vicinity of the bottom of the preceding excavation groove D1.

In the insertion operation S24, as shown in FIG. 5, the shape holding member 152 and the support member 17 are inserted into the space surrounded by the partition plate 11 and the cover member 151, and an end structure is formed at the end of the reinforcing bar unit 10. 1B is formed. The shape holding member 152 and the support member 17 are interposed between the tip of the connection member 12 and the cover member 151. In this embodiment, since the shape holding material 152 and the support material 17 are unitized, in the insertion operation S24, the shape holding material 152 and the support material 17 are inserted together. The shape maintaining material 152 and the support material 17 may be inserted separately. When the shape retaining material 152 is attached to the element frame 14 together with the cover material 151 in advance, only the support material 17 needs to be inserted in the insertion operation S24.
The end structure 1 </ b> B is a portion formed by the partition plate 11, the connecting member 12, and the space forming member 15. Here, the space forming member 15 is a member for forming a space around the connection member 12, and includes a cover material (cover portion) 151 and a shape holding material (shape holding portion) 152.

  The shape retaining material 152 is a member attached to the tip of the connection member 12. The shape-retaining material 152 of this embodiment can be cut by ground excavation, and is composed of a plate material on which a plurality of irregularities are formed as shown in FIG. The shape maintaining material 152 of the present embodiment is provided with a plurality of frustum-shaped concavities and convexities, and has a wave shape in a plan view and a longitudinal view. That is, the shape retaining material 152 has an egg pack shape. The form of the shape retaining material 152 is not limited. For example, as shown in FIG. 7B, a corrugated plate material may be used. Moreover, as shown in FIG.7 (c), you may arrange a wave-shaped strip | belt-shaped member in parallel with an up-down direction. Note that the shape retaining material 152 shown in FIG. 7C is fixed to the protective plate 171.

In the present embodiment, as shown in FIG. 5, a protection plate 171 is interposed between the connection member 12 and the shape retaining member 152 (space forming member 15).
The protection plate 171 is detachably coupled to the partition plate 11 via a coupling steel material 172 and covers the distal end surface of the connection member 12. A shape retaining material 152 is attached to the trailing element 2 side of the protection plate 171.
The protection plate 171 of this embodiment constitutes the support member 17 of the space forming member 15 (shape holding member 152) together with the connecting steel member 172. In addition, the structure of the support material 17 is not limited. Further, the shape retaining material 152 is not necessarily attached to the protective plate 171. In addition, a gap may be formed between the shape maintaining material 152 and the protection plate 171.

The protection plate 171 is a plate member interposed between the connection member 12 and the shape holding member 152 and extends in the height direction. A plurality of connecting steel materials 172 are fixed to the surface of the protection plate 171 on the partition plate 11 side. The protection plate 171 may be any material as long as it can protect the connection member 12 when excavating the subsequent excavation groove D2, and the material and shape thereof are not limited. For example, a perforated plate material or a lattice plate material may be used.
The connecting steel material 172 is made of a channel material and extends in the height direction. The length (height) of the web of the connecting steel material 172 is larger than the length of the connecting member 12 (projection length from the partition plate 11). One flange of the connecting steel material 172 is fixed to the protective plate 171, and the other flange is locked to the partition plate 11. In the present embodiment, a locking member 111 having an L shape in plan view is disposed between the connection members 12 of the partition plate 11. The support member 17 is attached to the partition plate 11 by locking (sliding in) the other flange of the connecting steel material 172 to the locking member. In addition, the material which comprises the steel material 172 for a connection is not limited, For example, H-section steel and L-section steel may be sufficient.
As described above, in this embodiment, the end structure 1B is formed by covering the connection member 12, the shape holding member 152, and the support member 17 with the cover member 151 at the end portion of the reinforcing bar unit 10.

In the placing operation S25, as shown in FIG. 4C, concrete (fresh concrete 30) is placed in the preceding excavation groove D1.
The fresh concrete 30 is placed from the bottom surface of the preceding excavation groove D1 using the tremy pipe P. The tremy pipe P is raised as the upper surface of the fresh concrete 30 is raised. At this time, the end structure 1 </ b> B is surrounded by the partition plate 11 and the cover material 151, so that concrete is not placed therein.

The subsequent excavation step S3 is a step of excavating a subsequent excavation groove D2 continuous to the preceding excavation groove D1, as shown in FIG. 4 (d).
The subsequent excavation step is performed after a predetermined strength is developed in the concrete (preceding element 1) placed in the preceding excavation groove D1.
The excavation of the subsequent excavation groove D2 is performed while cutting the end portion of the preceding element 1. In addition, excavation of the trailing excavation groove D2 is performed by a ground excavator (not shown) similarly to the preceding excavation groove D1.
By the excavation of the trailing excavation groove D2, the cover material 151 and the shape holding material 152 provided at the end of the preceding element 1 are cut. By cutting the cover material 151, a recess 1 </ b> A is formed at the end of the preceding element 1.

The succeeding formation step S4 is a step of forming the succeeding element 2 continuous with the preceding element 1 in the succeeding excavation groove D2 (see FIG. 1).
As shown in FIG. 3C, the subsequent formation step S4 of the present embodiment includes an assembly operation S41, an erection operation S42, and a placement operation S43.
In the assembly work S41, the reinforcing bar 4 is assembled to the element frame 23 to form the reinforcing bar unit 20. The assembly operation S41 may be performed after the subsequent excavation step S3, or may be performed before or in parallel with the subsequent excavation step S3.

In the erection operation S42, the reinforcing bar unit 20 is inserted into the subsequent excavation groove D2.
At this time, a spacer (not shown) is interposed between the reinforcing bar unit 20 and the inner wall surface of the subsequent excavation groove D2. The material, shape and arrangement of the spacer are not limited. Prior to insertion into the subsequent excavation groove D2 of the reinforcing bar unit 20, the remaining portions of the support member 17 and the shape holding member 152 are extracted from the recess 1A.
When the reinforcing bar unit 20 is installed in the subsequent excavation groove D2, the tremy pipe P is piped in the center of the reinforcing bar unit 10 (between the vertical members 232 on the center side). The tremy tube P is inserted until the tip (lower end) reaches the vicinity of the bottom of the subsequent excavation groove D2.

In the placement work S43, the concrete 30 is placed in the subsequent excavation groove D2.
The concrete 30 is placed from the bottom surface of the subsequent excavation groove D2 using the tremy pipe P. The tremy pipe P is raised as the upper surface of the cast concrete is raised. The concrete 30 also enters the concave portion 1A to form the convex portion 2A and hardens in a state where the connecting member 12 and the water stop plate 13 are involved (see FIG. 1).

As described above, according to the end element structure of the preceding element and the construction method of the underground continuous wall of the present embodiment, it is possible to easily construct the underground continuous wall ensuring water-stopping and cross-sectional force transmission performance. That is, since the cover portion can be cut when constructing the excavation groove for the succeeding element, the connecting member and the water stop plate are exposed, and as a result, the succeeding element is constructed with the connecting member and the water stop plate being caught. Can do.
Since the connection member 12 is disposed in the recess 1A, the ground excavator does not come into contact with the subsequent excavation groove D2. Moreover, since the support material 17 is inserted together with the shape maintaining material 152 in the insertion operation, the joining member 12 can be protected during the subsequent excavation.
Moreover, even if it is a case where the underground continuous wall with a large wall thickness is formed by inserting the shape maintaining material 152, the distance between the fulcrums of the cover material 151 does not increase.

  Since the leading element 1 and the trailing element 2 are engaged by the concave portion 1A and the convex portion 2A, they have excellent bonding properties. The preceding element 1 and the succeeding element 2 are continuous structures that transmit the cross-sectional force via the connecting member 12 and the connecting bar 21. Moreover, since the joining surface (the recessed part 1A and the projecting part 2A) of the preceding element 1 and the succeeding element 2 is bent, the water stoppage is improved by extending the length of water leakage that penetrates the joining surface. Yes.

The embodiment of the present invention has been described above. However, the present invention is not limited to the embodiment, and the above-described constituent elements can be appropriately changed without departing from the spirit of the present invention.
For example, in the above-described embodiment, the case where the shape maintaining material 152 is configured by a plate that can be cut has been described. That is, it is a material that prevents deformation of the cover material 151 by resisting the concrete pressure at the time of placing work, and does not interfere with the formation of the subsequent excavation groove D2 by being bent or crushed when excavated by the ground excavator. Also good. When a deformable material is used as the shape holding material 152, the shape holding material 152 is extracted from the recess together with the support material 17 in the subsequent forming step.
Further, in the above-described embodiment, the case where the shape holding material 152 is installed in the insertion process has been described. However, the shape holding material 152 is fixed to the cover material 151 in advance, so that the element together with the cover material 151 is used in the preceding forming process. It may be attached to the frame 14.

In the above-described embodiment, the space forming member 15 is a combination of the cover material 151 and the shape retaining material 152. However, the space forming member 15 is integrally formed of the cover material 151 and the shape retaining material 152. It may be what was done.
The shape maintaining material 152 may be a solid member that can be cut as shown in FIG.
Further, the shape retaining member 152 may be a member configured to be able to be locked to the head of the connecting member 12 as shown in FIG. For example, the member provided with the latching | locking part 152a of a C-shape by plane cross section and the convex-shaped convex part 152b may be sufficient. With such a shape retaining material 152, the support material 17 can be omitted.

Although the support material 17 of the said embodiment demonstrated the case where the some steel material 172 for a connection was locked in the state contact | abutted on the surface of the partition plate 11, the structure of the support material 17 is not limited to this. Absent. For example, as shown in FIG. 9A, the connecting steel member 172 provided at the edge of the support member 17 may be engaged with the attachment member 16.
Further, as shown in FIG. 9B, the support member 17 may lock the engagement member 173 formed on the surface of the protection plate 171 on the partition plate 11 side to the head of the connection member 12.
The support material 17 extracted in the subsequent forming step S4 can be diverted to other preceding elements.

DESCRIPTION OF SYMBOLS 1 Leading element 1A Recessed part 1B End part structure (End part structure of a leading element)
DESCRIPTION OF SYMBOLS 10 Reinforcing bar unit 11 Partition plate 12 Joining member 13 Water stop plate 14 Element frame 15 Space forming member 151 Cover material (cover part)
152 Shape retainer (shape retainer)
17 Support material 171 Guard plate 2 Subsequent element 2A Convex 3 Concrete 4 Reinforcing bar D1 Lead excavation groove D2 Subsequent excavation groove

Claims (8)

A partition plate disposed at the boundary between the preceding element and the succeeding element;
A connecting member protruding from the side surface of the trailing element on the partition plate;
A space forming member that forms a space around the connection member, and an end portion structure of a preceding element comprising:
The space forming member has a shape holding part attached to the tip of the connection member, and a cover part that covers the connection member and the shape holding part,
An end structure of a preceding element, wherein at least the cover part can be cut by a ground excavator. The shape holding portion includes a plate material on which a plurality of irregularities are formed,
The end structure of the preceding element according to claim 1, wherein the plate material can be cut by a ground excavator or can be deformed when excavated by the ground excavator.   The end structure of the preceding element according to claim 1, wherein the shape holding part is a solid member that can be cut by a ground excavator. Between the connection member and the space forming member, a protective plate detachably connected to the partition plate is interposed,
The end structure of the preceding element according to any one of claims 1 to 3, wherein the shape holding portion is in contact with the protection plate. A preceding excavation process for excavating the preceding excavation groove;
A preceding forming step of forming a preceding element in the preceding excavation groove;
A subsequent excavation step of excavating a subsequent excavation groove continuous to the preceding excavation groove;
A subsequent formation step of forming a subsequent element that is continuous with the preceding element in the subsequent excavation groove, and a construction method of an underground continuous wall comprising:
The preceding forming step includes
Assembling work for assembling the reinforcing bar unit and the partition plate to the element frame to form a reinforcing bar unit;
Cover installation work that installs a cover material that can be cut by a ground excavator at the end of the reinforcing bar unit, and covers the connection member protruding from the partition plate with the cover material;
Construction work for inserting the reinforcing bar unit and the cover material into the preceding excavation groove,
An insertion operation of inserting a shape-retaining material into a space surrounded by the partition plate and the cover material;
And placing work for placing concrete in the preceding excavation groove,
In the insertion operation, the shape retaining material is interposed between the tip of the connecting member and the cover material.   6. The underground continuous wall construction method according to claim 5, wherein, in the insertion work, a support material is inserted between the shape maintaining material and the connecting member together with the shape maintaining material. A preceding excavation process for excavating the preceding excavation groove;
A preceding forming step of forming a preceding element in the preceding excavation groove;
A subsequent excavation step of excavating a subsequent excavation groove continuous to the preceding excavation groove;
A subsequent formation step of forming a subsequent element that is continuous with the preceding element in the subsequent excavation groove, and a construction method of an underground continuous wall comprising:
The preceding forming step includes
Assembling work for assembling the reinforcing bar unit and the partition plate to the element frame to form a reinforcing bar unit;
A space installation member that can be cut by a ground excavator at the end of the reinforcing bar unit, and a cover installation operation that covers the connection member protruding from the partition plate with the space formation member;
Construction work for inserting the reinforcing bar unit and the cover material into the preceding excavation groove,
An insertion operation of inserting a support material into a space surrounded by the partition plate and the space forming member;
And placing work for placing concrete in the preceding excavation groove,
In the inserting operation, the support material is interposed between the connection member and the space forming member.   The underground continuous wall construction method according to claim 6 or 7, wherein the supporting material is extracted from the space in the subsequent forming step.

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