JP5670304B2 - Earth retaining wall for shield excavation - Google Patents

Description

  The present invention relates to a retaining wall for shield excavation of a shaft formed in a shield method.

Conventionally, a shield construction method using a shield excavator has been widely adopted as tunnel construction for subways, roads, common grooves, and sewers.
Generally, in this shield method, a vertical shaft (starting shaft) is first formed by an open-cut method, and a shield excavator is carried underground from this starting shaft, and the excavation side of the starting shaft is excavated by the shield excavator. Then, it is a construction method that starts in the horizontal direction and excavates the tunnel to the end point that is the destination point. Normally, in such a shield method, a vertical hole similar to the start shaft (reach shaft) is formed at the end point of the tunnel and the intermediate point until the end point is reached, and the shield excavator reaches the reach shaft Let

  By the way, in the start shaft and the reach shaft (hereinafter, both are collectively referred to as a shaft) formed by the open-cut method, the excavation wall surface is reinforced from the viewpoint of ensuring safety during operation. In other words, reinforced concrete, groove sheet piles, H-shaped steel, etc. are used on the excavation side of the shaft to prevent the wall from collapsing due to earth pressure or water pressure (hereinafter referred to as earth pressure) or groundwater outflow from the wall. The retaining wall, which is the temporary wall used, is constructed, and in some cases, measures such as improving the surrounding ground are taken.

However, in the shield method, it is a retaining wall provided from the viewpoint of safety, etc., but for tunnel excavation, the retaining wall is removed after ground improvement or a shield excavator against the retaining wall. An opening for allowing the light to pass therethrough is formed (so-called mirror cutting). And since these operations need to be performed within a limited area of a shaft, it has been necessary to work manually, and there has been anxiety about safety at the time of work, as well as a longer construction period and construction costs. It was a factor causing an increase in
Therefore, in tunnel construction using the shield method, it is desired to improve work efficiency and safety in the shaft.

  Therefore, in recent years, a member composed of a polyurethane foamed resin molded body (abbreviated as FFU: Fiber reinforced foamed urethane) reinforced with long fibers is incorporated into the earth retaining wall of the shaft, and the portion where the FFU member is incorporated is incorporated. There is a shield construction method in which cutting and direct cutting is performed directly with a shield excavator (abbreviated as SEW construction method: Shield Earth Retaining Wall System). For example, Patent Document 1 discloses the technique.

  Specifically, in the SEW method disclosed in Patent Document 1, a rod-shaped cutting enabling member formed by laminating FFU laminates up to a predetermined thickness is placed in one direction at a position where it starts and reaches. An underground wall with a cutable area formed side by side so as to extend is adopted. That is, in Patent Document 1, the cutable area formed by FFU is made a wall surface that reinforces the excavation side surface, but the area can be directly cut by the shield excavator, so that the work efficiency and safety are improved. Has succeeded.

Japanese Patent No. 2821556

  However, the earth retaining wall in Patent Document 1 can withstand the earth pressure applied to the rear surface of the retaining ring up to a certain value, but at a certain depth or more, for example, at a depth of 60 m or more from the ground surface, it exceeds the allowable pressure resistance. I was dissatisfied.

  Therefore, in an environment of a certain depth or more, in order to ensure sufficient strength that can withstand earth pressure, etc., the amount of cutting enablement members arranged in parallel in one direction (actually the thickness of the member) is usually There is a concern that it may become a construction method that is not feasible from the viewpoint of cost because the material cost is remarkably increased if this measure is adopted.

  Therefore, in the present invention, in view of the problems of the prior art, even in a deep shaft where the earth pressure or water pressure applied to the back of the earth retaining wall is greater than a certain level while ensuring the ease of excavation by a shield excavator. An object of the present invention is to provide a shield excavation retaining wall that can be used and can suppress an increase in cost.

One invention for solving the above-mentioned problem is that a shield wall formed by a cement mixed material in which at least cement and water are mixed and a metal reinforcing material is used, and shield excavation is performed on a part of the retaining wall. A shield excavation retaining wall having a cutable area that can be cut by a machine, and having a long resin body formed in a long shape with a foamed resin molded body reinforced with long fibers, the cuttable area is An earth retaining wall for shield excavation, characterized by having a three-dimensional lattice portion in which a long resin body is three-dimensionally intersected.

The invention according to claim 1 for solving the above-mentioned problems is a retaining wall formed of a cement mixture and a metal reinforcing material, and a part of the retaining wall can be cut by a shield excavator. A shield excavation retaining wall having a cutable area, which has a plurality of long resin bodies formed in a long shape with a foamed resin molded body reinforced with long fibers, and the cuttable area has one long length A long resin body and a cement mixture material, each of which has a three-dimensional lattice portion in which a long resin body is three-dimensionally overlapped and crossed with another long resin body, and is formed by adhering the cement mixed material to the long resin body It is the earth retaining wall for shield excavation characterized by providing the composite_body | complex of.

  The earth retaining wall for shield excavation according to the present invention has a structure in which a cuttable region that can be directly cut by a shield excavator includes a three-dimensional lattice portion. This three-dimensional lattice portion is a structure in which a long resin body formed of a foamed resin molded body is three-dimensionally crossed, and when the three-dimensional lattice portion is viewed from the front, a lattice point that is an intersecting portion is formed. is there. That is, the three-dimensional lattice part has long resin bodies arranged so as to extend in at least two different directions, and has lattice points where they intersect each other. In other words, the machinable region is formed by a three-dimensional lattice portion that is reinforced by overlapping a single reinforcing portion reinforced by a long resin body extending in one direction and a long resin body extending in at least two directions. A heavy reinforcement portion (same position as the lattice point) is formed. And since this double reinforcement part becomes the structure where the long resin body was substantially laminated | stacked by the number of the overlapping long resin bodies, intensity | strength is higher than a single layer reinforcement part in a cuttable area | region. A part is formed on the grid point.

In other words, according to the present invention, the long resin body is arranged so as to extend in at least two different directions, so that the region of the cuttable region can be obtained in a plan view as compared with the case of the one-direction arrangement described above. The ratio of the long resin body in the plane can be substantially increased, and the strength of the cuttable region can be expected as a surface, and a double reinforced portion having higher strength than the single reinforced portion is provided on the surface in the cuttable region. Since it can be formed, the strength can be drastically improved by the synergistic effect of the strength by the surface and the strength by the point. And by this effect, in this invention, in order to obtain the intensity | strength comparable as or more than the intensity | strength which can be exhibited in the case of the conventional one-way arrangement | positioning, the amount of members of a long resin body can be decreased.
Therefore, the earth retaining wall for shield excavation according to the present invention can drastically improve the strength without greatly increasing the amount of the long resin body by providing the three-dimensional lattice portion in the cuttable region. As a result, it is possible to obtain a temporary wall that can withstand earth pressure and water pressure in a deep environment, which is difficult in the case of a cuttable region in which a long resin body is arranged in only one direction.

  Here, with regard to the prior art, the shield wall for shield excavation of the prior art uses only a long resin body extending in one direction as a reinforcing material for the cement mixed material, and the long resin body and the cement mixed material are integrated. Sex was not enough. That is, in the prior art, when the retaining wall is deformed by earth pressure or water pressure, the long resin body is also deformed, but the deformation makes the cement mixture easily separated from the long resin body. The integrity of the cement mixture and the long resin body was likely to collapse. Therefore, in the case where only a long resin body extending in one direction is used as a reinforcing material for the cement mixture, the design strength of the cuttable region in the retaining wall only takes into account the strength of the long resin body only. .

  Therefore, in the present invention, a three-dimensional lattice portion is provided so that the cement mixed material can be filled so as to straddle or be sandwiched between at least two long resin bodies arranged to extend in different directions. As a result, the entanglement between the cement mixed material and the long resin body becomes complicated, and the adhesion area of the cement mixed material to the long resin body increases, so that high integrity of both can be ensured. Further, with this configuration, as shown in FIG. 8, even if the long resin body is deformed, the cement mixed material is sandwiched between the deformed long resin bodies, or resists earth pressure or water pressure. Since the cement mixed material is dammed, it is unlikely that the integrity of the cement mixed material and the long resin body will collapse. Therefore, in the present invention, unlike the prior art, the design strength of the cuttable region in the retaining wall can be designed as a composite of the long resin body and the cement mixture.

In addition, along with this, the absolute amount of the long resin body can be reduced by taking into account the strength of the cement mixture. That is, according to the present invention, it is possible to further reduce the amount of members of the long resin body while ensuring a certain strength or more, so there is no risk that the material cost will increase.
According to the above, since the present invention has the three-dimensional lattice portion in the cuttable region, the depth of earth pressure and water pressure applied to the back of the earth retaining wall is a certain level or more while ensuring the ease of excavation by the shield excavator. Even a vertical shaft can be employed, and further, the increase in cost can be suppressed by reducing the amount of the long resin body used.

The earth retaining wall for shield excavation of the present invention, the three-dimensional lattice portion has a row direction arrangement portion in which long resin bodies are arranged in the row direction, and a column direction arrangement portion in which long resin bodies are arranged in the column direction, It is desirable that the row direction arrangement portion and the column direction arrangement portion are arranged close to or away from each other.
Note that “proximity” as used herein includes a state in which the row direction arrangement portion and the column direction arrangement portion are in contact with each other.

According to a second aspect of the present invention, in the composite, a plurality of long resin bodies are arranged in a row direction, and a plurality of long resin bodies are arranged in a column direction. And a column direction arrangement part that forms a plane different from the one plane, and the row direction arrangement part and the column direction arrangement part form a plurality of three-dimensional lattice parts. The earth retaining wall for shield excavation according to 1.

  The invention according to claim 3 is the earth retaining wall for shield excavation according to claim 1 or 2, wherein the long resin body is formed by laminating a plurality of laminated plates.

  According to such a configuration, the thickness of the long resin body can be changed depending on the number of laminated plates, and therefore can be adjusted according to the environment in which the retaining wall is installed. That is, according to the present invention, it is possible to prevent the thickness of the long resin body from being excessively larger or smaller than the design strength.

  The invention according to claim 4 is the earth retaining wall for shield excavation according to any one of claims 1 to 3, wherein the long fibers of the long resin body are made of glass.

  According to this structure, since the long fiber which a long resin body has is a product made from glass, when cutting with a shield excavator, glass fiber is destroyed easily. That is, the shield retaining wall for shield excavation of the present invention is easy to excavate and has high strength against earth pressure and the like.

Invention described above, the three-dimensional grid part may possess a dense portion elongated resin body is tightly crossed, and a scattered portion of the elongated resin body crosses sparsely.

Generally, the design strength of a structure is a design on the safe side, and therefore the design strength is determined based on a large external force assumed. That is, the design strength of the retaining wall is determined based on the earth pressure at a position where the depth is large. For this reason, the design strength may be excessively increased at a position where the depth is small.
Therefore, the shield excavation retaining wall of the present invention is configured to be able to change the density of the lattice points of the three-dimensional lattice portion in accordance with the back earth pressure. For example, in one earth retaining wall, if the deep part is a dense part and the shallow part is a scattered part, the deep part where the back earth pressure is large is reinforced intensively, and conversely the shallow part where the back earth pressure is small. Since the portion can be reinforced to an appropriate strength, a shield excavation retaining wall balanced in terms of both strength and cost can be provided to the market.

According to a fifth aspect of the present invention, the three-dimensional lattice portion has a plurality of lattice points where one long resin body and another long resin body intersect in the plane of the cuttable region, and the cutting 5. The shield retaining wall for shield excavation according to claim 1, wherein in the possible area, the shield excavation retaining wall according to any one of claims 1 to 4 has a dense portion where the lattice points are dense and a scattered portion where the lattice points are sparse.

Invention according to claim 6, wherein the metal reinforcing member is rebar, the end portion of the elongated resin body is provided with a metal auxiliary connecting member, rebar, auxiliary connecting end member The earth retaining wall for shield excavation according to any one of claims 1 to 5, wherein the earth retaining wall is joined via a gap.

  According to such a configuration, since the long resin body and the reinforcing bar are joined by welding or the like via the auxiliary connecting member, the long resin body and the reinforcing bar are highly integrated. The rate of decrease in strength at the boundary is small. In other words, since the long resin body and the reinforcing bar can be firmly joined, the resistance against the earth pressure and the like of the long resin body can be surely exhibited.

  Since the earth retaining wall for shield excavation according to the present invention is provided with a three-dimensional lattice portion obtained by three-dimensionally intersecting a long resin body in the excavation enabling region, the earth pressure applied to the back of the earth retaining ring is secured while ensuring the excavation ease by the shield excavator Even a deep shaft with a water pressure larger than a certain level can be used. Even if the strength is increased, an extreme increase in cost can be prevented.

It is a perspective view which shows the condition which installed the earth retaining wall for shield excavation which concerns on embodiment of this invention in the vertical shaft. It is a conceptual diagram which shows the condition at the time of excavating the earth retaining wall for shield excavation of FIG. 1 with a shield excavator. It is an expansion perspective view which shows a part of elongate resin body. It is a figure which shows the three-dimensional lattice part of FIG. 1, (a) is a perspective view, (b) is a front view which shows notionally the relationship with the magnitude | size of the bit of a shield excavator. (The two-dot chain line indicates the cutting area of the shield excavator.) It is a perspective view which shows the connection part of a long resin body and a deformed reinforcing bar. It is a conceptual diagram which shows a row direction arrangement | sequence part. It is a conceptual diagram which shows a column direction arrangement | sequence part. It is a conceptual diagram which shows the condition when the earth retaining wall for shield excavation deform | transforms by the influence of earth pressure and water pressure, (a) is before a deformation | transformation, (b) is after a deformation | transformation. It is explanatory drawing which shows notionally the condition which set the box on the ground. It is explanatory drawing at the time of installing the concrete reinforcing material in the vertical hole for placement of FIG. It is explanatory drawing which shows the condition at the time of driving in fresh concrete after installing the concrete reinforcing material of FIG. 1 is a cross-sectional view conceptually showing a distributed weighted loading test apparatus. It is a perspective view which shows the external appearance of a test body. It is the figure which paid its attention to the solid lattice part of the implementation test body 40, (a) is the conceptual diagram which planarly viewed the inside, (b) is sectional drawing. It is the figure which paid its attention to the elongate resin body of the comparative test body 41, (a) is the conceptual diagram which planarly viewed the inside, (b) is sectional drawing. It is a graph which shows the relationship between the water pressure and center displacement in an implementation test body and a comparative test body. It is a modified example of the shield wall for shield excavation, and is a conceptual diagram showing a cuttable region having a dense portion and a scattered portion.

Below, the earth retaining wall 1 for shield excavation which concerns on embodiment of this invention is demonstrated.
As shown in FIGS. 1 and 2, the shield excavation retaining wall 1 according to the present embodiment reinforces the excavation side surfaces of the vertical shafts 30 and 31 which are vertical holes excavated from the ground toward the ground when excavating the shield tunnel. It is a temporary wall of concrete structure and forms part of the walls of the shafts 30 and 31. Specifically, it is a temporary wall that reinforces the excavation side surface of the shafts 30 and 31 on the side excavated by the shield excavator 9 (FIG. 2). That is, the shield excavation earth retaining wall 1 of the present embodiment plays a role of preventing the excavation side surface from collapsing due to the influence of earth pressure, water pressure or the like (hereinafter referred to as earth pressure or the like).

  Moreover, the earth retaining wall 1 for shield excavation of this embodiment is provided with the cuttable area | region 2 which can be directly cut by the shield excavator 9, and SEW which is temporary wall cutting method among many methods in a shield method. The construction method (Shield Earth Retaining Wall System) can be implemented. That is, the earth retaining wall 1 for shield excavation starts from the vertical shaft (starting shaft) 30 in the lateral direction and from the tunnel 32 that is a horizontal hole excavated from the starting shaft 30 to the vertical shaft (reach shaft) 31 (FIG. 2). When it reaches, it is set as the structure which can aim at the ease and efficiency of excavation work.

Therefore, the earth retaining wall 1 for shield excavation of this embodiment is mainly composed of a concrete structure, and includes a known deformed reinforcing bar 20, a long long resin body 6 reinforced with long fibers, the deformed reinforcing bar 20 and a long length. It is the structure provided with the connection auxiliary member 15 (FIG. 5) which connects the scale resin body 6 integrally. Specifically, the earth retaining wall 1 for shield excavation according to the present embodiment has a rectangular shape as a whole, a main structure wall portion 5 that is a main structure in which the concrete interior is reinforced by deformed reinforcing bars 20, and a long length in the concrete interior. It is comprised with the resin arrangement | positioning wall part 3 by which the length resin body 6 is arrange | positioned.
Needless to say, concrete is a cement mixed material in which cement, water and crushed stone are mixed.

  Here, as shown in FIG. 3, the long resin body 6 in the present embodiment is a long shape molded using a polyurethane foamed resin (FFU: Fiber reinforced foamed urethane) reinforced with glass-made long fibers. And what was formed by laminating | stacking the laminated board 35 which is a thin fiber reinforced resin foam until it reaches predetermined thickness is employ | adopted. In addition, each laminated plate 35 is configured such that the orientation of long fibers is along the longitudinal direction of the laminated plate 35. That is, the long resin body 6 is a member having high rigidity facing a bending moment acting in a direction intersecting the longitudinal direction. On the other hand, since the reinforcing resin is made of glass, the long resin body 6 is also a member having high ease of cutting because it is easily broken by cutting of the shield excavator 9 as compared with metals such as reinforcing bars. .

Then, inside the concrete, as shown in FIG. 5, the deformed reinforcing bar 20 of the main structural wall 5 and the long resin body 6 of the resin arrangement wall 3 are integrated by welding or the like via the connection auxiliary member 15. It is connected to the.
As shown in FIG. 5, the connection auxiliary member 15 includes two metal plate bodies 38, and is arranged so that a part of the long resin body 6 projects from the end portion of the long resin body 6. It can be attached. The deformed reinforcing bar 20 of the main structural wall 5 is connected to the end of the long resin body 6 (the end of the plate 38 that forms the outermost surface) by welding or the like. The connection auxiliary member 15 has a hole penetrating in the thickness direction of each of the two plate bodies 38, and the two plate bodies 38 are arranged at positions sandwiching the long resin body 6. They are attached using connecting means such as bolts and nuts.
Therefore, as shown in FIGS. 2 and 5, the shield excavation earth retaining wall 1 is formed with a mixed wall portion 19 where the main structural wall portion 5 and the resin arrangement wall portion 3 overlap as shown in FIGS. It is also a structure. In other words, the mixing wall portion 19 is a part of the main structural wall portion 5 and also a part of the resin arrangement wall portion 3. And in this embodiment, the area | region remove | excluding the mixing wall part 19 from the resin arrangement | positioning wall part 3 is made into the cutting possible area | region 2. FIG.

  Moreover, the earth retaining wall 1 for shield excavation of this embodiment has the resin arrangement | positioning wall part 3 located in the downward side of the vertical shafts 30 and 31, and the shield excavator 9 starts from the position of the resin arrangement wall part 3. It is configured to reach. In other words, the shield excavation retaining wall 1 includes, as shown in FIG. 2, an upper region 16 from the ground (upper side) to the resin arrangement wall portion 3, and a lower region in which the resin arrangement wall portion 3 is located. A region excluding the cuttable region 2 in 17 is constituted by the main structural wall portion 5. In addition, since the main structure wall part 5 is a well-known part provided with the reinforced concrete structure, it abbreviate | omits the description below and demonstrates it paying special attention to the resin arrangement | positioning wall part 3. FIG.

As shown in FIG. 6, the resin arrangement wall portion 3 includes a row direction arrangement portion 21 in which a plurality of long resin bodies 6 are arranged in parallel in the row direction to form one plane, and as shown in FIG. A row direction arrangement portion 22 that is arranged in parallel in the row direction to form another plane, and the row portions 21 and 22 are in contact with each other so as to cross three-dimensionally. As shown in FIG. 4, the wall portion is formed by forming the three-dimensional lattice portion 11. That is, the three-dimensional lattice part 11 is arranged so that the long resin body 6 extends in two different directions, so that the ratio of the cuttable region 2 to the plane can be substantially increased and the strength can be exhibited as a surface. Part. In other words, the resin arrangement wall portion 3 has a configuration in which the orientation of the long fibers of the long resin body 6 is also intersected by the three-dimensional lattice portion 11. As described above, the resin arrangement wall portion 3 three-dimensionally intersects the long resin bodies 6 arranged in two different directions to form lattice points where the long resin bodies 6 overlap with each other. In this configuration, the strength (specifically, bending strength and shear strength) that can counter the external force applied in the stacking direction of the body 6 is further improved.
Therefore, the resin arrangement wall portion 3 is a wall portion having a configuration in which the strength can be expected as a surface and the strength is synergistically improved by the strength increasing portions (lattice points) formed on the surface.

  In the present embodiment, the arrangement and size of the long resin bodies 6 forming the three-dimensional lattice portion 11 are determined in accordance with the shape of the excavation opening by the shield excavator 9 (the bit is circular in this embodiment). Yes. That is, the row direction arrangement portion 21 and the column direction arrangement portion 22 are longer in the longitudinal direction length of the long resin body 6 as they approach the outer side in the arrangement direction of the long resin body 6 (the edge side of the bit circle of the shield excavator 9). Has a short configuration. Specifically, the long resin bodies 6 that form the row direction arrangement portion 21 and the column direction arrangement portion 22 are arranged on the basis of the bit shape of the shield excavator 9 as shown in FIG. The total length in the longitudinal direction is set so that the length M that protrudes from the circle is within 10 to 20% of the total length in the longitudinal direction. Has been. In other words, the long resin body 6 is arranged such that the end portion thereof follows the circular shape of the excavation opening by the shield excavator 9. More specifically, in the present embodiment, the resin arrangement wall portion 3 has a region in which the deformed reinforcing bars 20 are arranged in a triple shape in a circular shape, and the inner circle of the deformed reinforcing bars 20 in the circular shape. The end of the long resin body 6 is arranged along the line.

  In addition, the resin arrangement wall portion 3 has a configuration in which the thickness of the wall portion in the cuttable region 2 is thinner than the thickness of the wall portion of the main structural wall portion 5. This is an advantage brought about by three-dimensionally crossing the long resin body 6 in the resin arrangement wall portion 3. That is, by making the long resin body 6 cross three-dimensionally, the concrete is entangled with the long resin body 6 in a complicated manner, so that the integrity of both is dramatically improved. As a result, as shown in FIG. 8, the unity of both is maintained regardless of whether or not the resin arrangement wall portion 3 is deformed. Therefore, in the present embodiment, a design strength of a certain level or more is ensured. In this case, it can be calculated as a composite of the long resin body 6 and concrete, and it is not necessary to increase the thickness of the long resin body 6 more than necessary. Therefore, even in order to ensure high strength in the cuttable region 2, it is not necessary to increase the thickness of the long resin body 6 (the number of laminated plates 35) by forming the three-dimensional lattice portion 11. As a result, an increase in the overall thickness in the cuttable region 2 does not occur. Therefore, the cuttable region 2 in the present embodiment can have a thinned structure while ensuring a design strength of a certain level or more.

Next, a method of constructing the shafts 30 and 31 using the shield excavation retaining wall 1 of the present embodiment will be described.
As described above, the shield excavation earth retaining wall 1 is used for the shield method, and is provided so as to reinforce the excavation side surfaces of the start shaft 30 and the arrival shaft 31. And in this embodiment, the earth retaining wall 1 for shield excavation is formed in the ground by a well-known caisson method. The caisson method can be broadly divided into an open caisson method and a pneumatic caisson method. In this embodiment, the pneumatic caisson method is adopted.

  First, a reinforced concrete box 39 having shield retaining walls 1 for shield excavation is formed on the ground. The box 39 is open on the upper surface side, and the shield excavation retaining wall 1 is formed on one side wall. Further, the shape of the longitudinal section of the box 39 is substantially “H” type, and the excavation work chamber 45 is provided at the lower part. The excavation work room 45 is a room for excavating the ground downward.

  And the box 39 is arrange | positioned in a predetermined position, as shown in FIG. That is, when the box 39 sinks into the ground, it is set so that the back side (underground wall) of the shield excavation retaining wall 1 is positioned on the tunnel 32 side to be excavated. Thereafter, a person enters the excavation work chamber 45 and excavates downward, or is excavated downward by an unillustrated unmanned excavator, and the box 39 is directed underground as shown in FIG. Allow to settle.

Thereafter, when the excavation work is further carried out in the excavation work chamber 45, the box 39 reaches a predetermined depth, and at the same time, the shield excavation earth retaining wall 1 is set at the tunnel 32 planned excavation position. Then, when the groundwater and earth and sand accumulated in the box 39 are discharged, the start shaft 30 is completed.
The reaching shaft 31 is also constructed by the same method as described above, and thus the description thereof is omitted.

Next, a method for forming a shield tunnel from the starting shaft 30 to the reaching shaft 31 using the shield excavator 9 will be described.
First, the shield excavator 9 is lowered from the ground into the start shaft 30, and as shown in FIG. 2, the shield excavator 9 is arranged so that the bits of the shield excavator 9 face each other in the cuttable region 2 of the shield excavation retaining wall 1. Start digging the tunnel.
Here, since the area in front view of the cutable area 2 of the shield excavation retaining wall 1 is larger than the area of the bit of the shield excavator 9, the shield excavator 9 is made of concrete and long resin in the cuttable area 2. Only the body 6 is cut and does not contact the main structure wall 5 side.
If necessary, the ground on the back of the shield excavation retaining wall 1 is improved to ensure further safety.

  Then, the tunnel is dug by the shield excavator 9. Thereafter, the shield excavator 9 reaches the vicinity of the reaching shaft 31. The shield excavator 9 faces the cuttable area 2 of the shield excavation retaining wall 1 provided in the reaching shaft 31, cuts the concrete and the long resin body 6 in the area 2, and the shield excavator 9 arrives. The tunnel 32 passes through the shaft 31. At this time, the shield excavator 9 cuts only the concrete and the long resin body 6 in the cuttable region 2 and does not contact the main structure wall 5 side.

Next, the result of the strength test of the shield excavation retaining wall 1 of the present embodiment will be described.
Since the earth wall 1 for shield excavation of this embodiment becomes enormous when an actual construction site is assumed, a specimen having a predetermined size is manufactured for the strength test, and the strength of the earth wall 1 for shield excavation 1 A test was conducted to demonstrate this.

  The strength test performed this time was performed using a known method of loading a distributed load assuming earth pressure or water pressure. Then, by this test, as shown in FIG. 16, the displacement, cracks, etc. in the cuttable region, which occur according to the magnitude of the distributed load loaded on the test bodies 40, 41, are measured. Strength was confirmed.

The basic specifications common to the test bodies 40 and 41 will be described.
As shown in FIG. 13, the test bodies 40 and 41 are concrete structures having a substantially cylindrical shape and a structure in which a portion including the center is recessed in a circular shape. That is, the test bodies 40 and 41 are resin having a ring-shaped main structure wall portion 47 that mainly forms an outer shell and a cutable region 49 that has a thinner structure than the main structure wall portion 47 and that forms a hollow portion. The arrangement wall portion 48 is used.
Specific sizes of the test bodies 40 and 41 are shown below.
Overall outer diameter (outer diameter of main structural wall) R: 2900mm
Cutting area outer diameter Q: 1800mm
Interval r between outer diameter of main structural wall and cuttable area: 550 mm

A long resin body 46 is provided on the resin arrangement wall 48 of the test bodies 40 and 41 so as to spread over the entire surface of the cuttable region 49.
Long resin body 46: Fiber reinforced foamed urethane foam (FFU)

Next, individual specifications of the test bodies 40 and 41 will be described.
(Execution specimen 40)
The long resin body 46a forms the three-dimensional lattice portion 51 shown in FIGS. 14A and 14B in the cuttable region 49. FIG.
Long resin body 46a: sectional shape; square, sectional size; 45 mm × 45 mm
Cutting possible region 49a: interval between long resin bodies 46a arranged in parallel (interval between member cores); 135mm

(Comparative specimen 41)
The long resin body 46 b forms a one-way parallel arrangement portion 53 shown in FIGS. 15A and 15B in the cuttable region 49.
Long resin body 46b: sectional shape; square, sectional size; 90mm x 45mm
Cuttable region 49b: interval between long resin bodies 46d arranged in parallel (interval between member cores); 135mm

  Table 1 shows the water pressure and the central displacement when the test bodies 40 and 41 are broken.

  As apparent from FIG. 16 and Table 1, the test specimen 40 and the comparative test specimen 41 use the same amount of the long resin body, but the test specimen 40 having the three-dimensional lattice portion 51 is used. However, the magnitude of the central displacement and the water pressure at the time of destruction is better than that of the comparative test body 41 that does not have the three-dimensional lattice portion 51. That is, when the three-dimensional lattice portion is formed in the cuttable region, the amount of the long resin body to be used can be reduced and the strength that can withstand earth pressure can be increased.

  In the above-described embodiment, the configuration in which three-dimensional lattice points are uniformly formed in the plane of the cuttable region 2 is shown. However, the present invention is not limited to this, and for example, as shown in FIG. In the region, a configuration in which a portion (dense portion) 12 where the three-dimensional lattice points are dense and a portion (scattered portion) 13 where the three-dimensional lattice points are sparse may be formed. When this configuration is adopted, if the dense portion 12 is arranged on the deep side and the scattered portion 13 is arranged on the shallow side, it is possible to intensively increase the strength of the places with high earth pressure and water pressure. Therefore, it is possible to obtain both strength and cost benefits. As a result, a reasonable shield excavation retaining wall 4 can be provided to the market.

  In the above embodiment, the cuttable region 2 is formed in a substantially circular shape in accordance with the circular bit of the shield excavator 9, but the present invention is not limited to this, and the cuttable region 2 may be formed in another shape. I do not care. For example, the shape etc. which two circles connected are mentioned.

In the above embodiment, the row direction arrangement part 21 and the column direction arrangement part 22 forming the three-dimensional lattice part 11 are arranged to contact each other, but the present invention is not limited to this, and the row direction arrangement part 21 and The configuration may be such that the three-dimensional lattice portion is formed without contacting the column direction arrangement portion 22. That is, the three-dimensional lattice portion may be formed so that the row direction arrangement portion 21 and the column direction arrangement portion 22 are separated from each other. In this case, concrete is filled between the row direction arrangement portion 21 and the column direction arrangement portion 22 at the lattice points, but the strength against earth pressure or the like applied in the laminating direction of the long resin bodies 6 is increased. No worse than the above embodiment.
However, since the thickness of the cuttable region may increase by the amount of concrete that is additionally filled in the lattice points, the above embodiment is more preferable from the viewpoint of ease of cutting.

  In the said embodiment, although the structure using concrete as a cement mixing material was shown, this invention is not limited to this, The structure using mortar may be sufficient. However, since mortar has a lower strength as a structure than when concrete is used, it is preferable to use concrete as in the above embodiment.

  In the above embodiment, the configuration in which the entire shape of the shield excavation retaining wall 1 is rectangular is shown, but the present invention is not limited to this, and for example, a circular shape, an oval shape, an oval shape, a multi-purpose shape, etc. It may be a circular core type.

DESCRIPTION OF SYMBOLS 1 Shield excavation retaining wall 2, 49 Cutting possible area 3, 46 Resin arrangement wall part 5, 47 Main structure wall part 6 Long resin body 11, 53 Three-dimensional lattice part 15 Connection auxiliary member 20 Deformed bar (rebar)
21 row direction arrangement part 22 column direction arrangement part 30 start shaft 31 reach shaft 32 tunnel 35 laminated plates 40, 41, 42 test specimens 43, 44 comparative test specimens

Claims (6)

A cement admixture, in earth retaining wall formed by metal reinforcing member, a shield excavating soil retaining wall with a cuttable cuttable region by a shield excavator in a part of the earth retaining wall,
Having a plurality of long resin bodies formed into a long foam resin molded body reinforced with long fibers,
The cutting region may have a three-dimensional grid part crossed overlap one of the long resin body and sterically other elongated resin body,
A shield wall for shield excavation, comprising a composite of a long resin body and a cement mixture formed by adhering the cement mixed material to the long resin body . The complex is different from the row direction sequence portion forming a single plane by arranging a plurality of elongate resin members in the row direction, and the single plane by arranging a plurality of elongate resin body in the column direction A column direction arrangement part that forms a plane of
The earth retaining wall for shield excavation according to claim 1, wherein the row direction arrangement portion and the column direction arrangement portion are three-dimensionally crossed to form a solid lattice portion .   The earth retaining wall for shield excavation according to claim 1 or 2, wherein the long resin body is formed by laminating a plurality of laminated plates.   The earth retaining wall for shield excavation according to any one of claims 1 to 3, wherein the long fibers of the long resin body are made of glass. The three-dimensional lattice portion has a plurality of lattice points where one long resin body intersects with another long resin body in the plane of the cuttable region,
The earth retaining wall for shield excavation according to any one of claims 1 to 4, further comprising: a dense portion where lattice points are dense and a scattered portion where lattice points are sparse in the cuttable region. It said metal reinforcing member is a reinforcing bar,
At the end of the long resin body, a metal auxiliary connection end member is provided,
The earth retaining wall for shield excavation according to any one of claims 1 to 5, wherein the reinforcing bars are joined via auxiliary connection end members.

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