JP6444839B2 - Construction method for underground structures - Google Patents

Description

The present invention relates to a construction method for an underground structure .

  Conventionally, as a method of constructing a structure underground, there is a method of excavating the ground from the ground and constructing an underground structure by cast-in-place concrete. Moreover, there exists the method of using precast concrete for the part (for example, patent document 1, patent document 2).

JP 2008-2154 A JP 2000-337092 A

  However, as disclosed in Patent Document 1, a substantially rectangular precast concrete requires a wall thickness greater than a predetermined thickness in order to obtain a desired proof stress, and is not always efficient in manufacturing, transportation, installation, and the like.

  Further, as in Patent Document 2, it is difficult to ensure water-stopping by a method using arch-shaped precast concrete on a cast-in-place slab.

The present invention has been made in view of the above-described problems, and it is possible to reduce the thickness of a member using an arch action, which is excellent in water-stopping properties and can significantly reduce the work period. It aims at providing the construction method of a thing.

In order to achieve the above-described object, the first invention is a construction method for an underground structure, in which a segment a having an arch shape is installed at a predetermined position, and the segments are circumferentially and longitudinally arranged. And a step c of backfilling at least a part of the segment with fluidized soil, and a longitudinal direction of the segments on the outer peripheral surface of the segment. A first protrusion is provided as a positioning guide in the connection of the first, the step b aligns the positions of the first protrusions of the segments adjacent in the longitudinal direction, and penetrates the first protrusions; to linked by a linking member, further, the prestress imparted to tense the segments adjacent in the longitudinal direction, in the step c, a predetermined amount of the fluidizing treatment in the interior of the segment It is a construction method of underground structures, characterized by filling the soil.

  In the step a, a reinforcing member that suppresses opening of the opening side of the segment may be attached, and the reinforcing member may be removed after the segment is installed.

  The cross section of a part of the longitudinal direction of the precast structure constructed by the segments may be a substantially circular shape, and the other part of the cross section may have a shape of a part of a substantially circular opening.

According to 1st invention, an underground structure can be constructed easily. Moreover, the precast structure can be prevented from being lifted by filling the inside of the precast structure with a predetermined amount of fluidized soil. Moreover, the arch-shaped inner surface can be flattened by the fluidized soil.

  Further, by using the reinforcing member, it is possible to prevent the segment from being deformed and the opening from being opened during the lifting process or laying. Moreover, a reinforcement member can also be utilized as a hanging part.

  In addition, the shape of the tunnel at the exit from the underground tunnel to the ground is such that a part of the cross-section in the longitudinal direction of the precast structure is substantially circular and the other part of the cross-section is a part of a substantially circular opening. Can also respond.

ADVANTAGE OF THE INVENTION According to this invention, the construction method of the underground structure which can reduce the thickness of a member using an arch action, is excellent also in water-stopping, and can shorten a construction period significantly can be provided. .

The perspective view of the precast structure 1. FIG. The front view of the precast structure 1. FIG. (A) is the DD sectional view taken on the line A of FIG. 2, (b) is the EE sectional view taken on the line B of FIG. (A) is the F arrow directional view in the C section of FIG. 2, (b) is the GG sectional view taken on the line of (a). The figure which shows the process of installing the lower segment 3a. The figure which shows the lower segment 3a and the upper segment 3b which provided the reinforcement members 29a and 29b. The figure which shows other embodiment of the lower segment 3a and the upper segment 3b which provided the reinforcement members 29a and 29b. FIG. 6 is a cross-sectional view taken along the line II in FIG. The figure which shows the process of installing the upper segment 3b. The figure which shows the underground structure 43. (A) is the JJ sectional view taken on the line of FIG. 10, (b) is the KK sectional view of FIG. 10, (c) is the LL sectional view of FIG. FIG. 3 is a schematic cross-sectional view of the tunnel 51 in the longitudinal direction. It is a figure which shows the steel pipe sheet pile cylinder 79, (a) is sectional drawing of a vertical direction, (b) is a top view. It is a figure which shows the state which provided the gate 85 in the steel pipe sheet pile cylinder 79, (a) is sectional drawing of a vertical direction, (b) is a top view. (A) is a figure which shows the state which manufactured the precast structure 57 in the production yard 89, (b) is a figure which shows the process of towing the precast structure 57 to the sea. The figure which shows the offshore floating structure 90.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing a precast structure 1, and FIG. 2 is a front view. In addition, in FIG. 1, FIG. 2, illustration of the tension material etc. which are mentioned later is abbreviate | omitted.

  The precast structure 1 includes a lower segment 3a and an upper segment 3b. The lower segment 3a and the upper segment 3b have an arch shape. In the illustrated example, the precast structure 1 is shown as an example composed of two segments (lower segment 3a and upper segment 3b). However, if the precast structure 1 is composed of a plurality of segments, it is composed of three or more segments. Also good. The number of connections in the longitudinal direction of each segment is not limited to the illustrated example.

  Each of the lower segment 3a and the upper segment 3b has a guide protrusion 5 that is a first protrusion and a coupling protrusion 7 that is a second protrusion. A pair of guide protrusions 5 are formed on the arcs of the semicircular lower segment 3a and upper segment 3b. A pair of coupling protrusions 7 is formed at the tip of the semicircular lower segment 3a and upper segment 3b.

  Fig.3 (a) is the DD sectional view taken on the line A of FIG. FIG. 3A shows an example of the lower segment 3a, but the upper segment 3b has the same structure and will not be described. The guide protrusion 5 is formed on the outer peripheral surface of the lower segment 3a. The guide protrusions 5 are formed on both sides of the lower segment 3a in the width direction (longitudinal direction of the precast structure 1). That is, when the lower segments 3a are adjacent to each other in the width direction, the guide protrusions 5 face each other and contact each other.

  A hole 5 a is formed in the guide protrusion 5. By aligning the positions of the holes 5a between the lower segments 3a adjacent to each other in the width direction, the holes 5a are arranged on a substantially straight line. In this state, the connecting member 13 is inserted through the holes 5a of the guide protrusions 5 of the lower segments 3a adjacent in the width direction. The guide protrusions 5 are connected to each other by the connecting member 13.

  The connection between the lower segments 3a by the connecting member 13 is for positioning the lower segments 3a. That is, the guide protrusion 5 functions as a positioning guide for connecting the lower segments 3a in the longitudinal direction. Since the guide protrusion 5 is disposed on the outer peripheral surface of the lower segment 3a, positioning is easy.

  Further, as shown in FIG. 2, the lower segment 3a and the upper segment 3b are provided with holes 11 penetrating in the width direction. The holes 11 are provided at substantially the same pitch in the circumferential direction.

  FIG. 3B is a cross-sectional view taken along line E-E in a portion B of FIG. In FIG. 3B, an example of the lower segment 3a is shown as in FIG. 3A. However, the upper segment 3b has the same structure, and the description thereof is omitted. The hole 11 is provided at substantially the center in the thickness direction of the lower segment 3a. The tension member 15 is inserted into the hole 11. The tension member 15 penetrates the plurality of lower segments 3a. As described above, since the lower segments 3a are first positioned by the guide protrusion 5, the hole 11 is positioned and the tension member 15 can be easily inserted.

  Some or all of the lower segments 3a are provided with openings through which the holes 11 are exposed on the inner surface side. Therefore, the internal tension member 15 is exposed at the opening. The end of the tension member 15 is fixed to the opening of the lower segment 3 a by the anchor plate 17. Furthermore, a coupler sleeve 19 is provided at the end of the tension member 15 and can be connected via a coupler joint 21. For this reason, every time a predetermined number of lower segments 3a are connected in the longitudinal direction, the tension members 15 can be inserted through and connected to each other. For this reason, prestress can be given over the full length of the longitudinal direction of the connected lower segment 3a.

  The tensioning and fixing of the tension member 15 may be performed each time one lower segment 3a is connected, or may be performed every time a plurality of lower segments 3a are connected as described above.

  Here, the water stop members 9a and 9b are disposed on the opposing surfaces (end surfaces) of the lower segments 3a. In this way, prestress is applied over the entire length in the longitudinal direction of the connected lower segments 3a, and the water stop members 9a and 9b are disposed twice on the contact surfaces of each other. Water-stopping property can be ensured.

  FIG. 4A is a view taken in the direction of arrow F in a portion C of FIG. 2, and FIG. 4B is a cross-sectional view taken along the line GG of FIG. When the lower segment 3a and the upper segment 3b are combined to face each other, the coupling protrusions 7 face each other and come into contact with each other. The coupling protrusion 7 is provided with a hole 23 penetrating vertically. The number of holes 23 is not limited to the illustrated example.

  In a state where the hole 23 of the coupling protrusion 7 of the lower segment 3a and the hole 23 of the coupling protrusion 7 of the upper segment 3b are arranged on a substantially straight line, the hole 23 has a tension passing through the upper and lower coupling protrusions 7. The member 27 is inserted. By fixing the tension members 27 on the upper and lower surfaces of the coupling protrusion 7 in a state where the positions of the coupling protrusions 7 of the lower segment 3a and the upper segment 3b adjacent in the circumferential direction are aligned, the coupling protrusions 7 are tensioned. The member 27 is tensioned.

  Here, the water stop members 9c and 9d are disposed on the opposing surfaces (end surfaces) of the lower segment 3a and the upper segment 3b. In this way, the lower segment 3a and the upper segment 3b connected in the circumferential direction are connected by being tensioned by the tension member 27, and the water stop members 9c and 9d are arranged on the contact surfaces of the lower segment 3a. It is possible to ensure the water stoppage of the contact surface between 3a and the upper segment 3b.

  In addition, if the lower segment 3a and the upper segment 3b are connected in the circumferential direction, the precast structure 1 will be substantially circular. For this reason, the arch action can be used from any direction. For this reason, the thickness of the precast structure 1 can be made thin.

  Further, when the precast structure 1 uses the arch action, a tensile force is applied to the outer peripheral surface side of the precast structure 1. However, since the coupling protrusion 7 is disposed on the outer peripheral surfaces of the lower segment 3a and the upper segment 3b, not only is the connection easy, but a compressive force can be applied to the outer peripheral surface side of the precast structure 1. . For this reason, the connection part of the lower segment 3a and the upper segment 3b does not open, and a high water-stopping property can be ensured.

  Thus, in the precast structure 1, the lower segment 3a and the upper segment 3b are connected to each other in the circumferential direction and the longitudinal direction via the water stop members 9a, 9b, 9c, and 9d. In addition, since a prestressing force is applied, a high water-stopping property can be secured. In addition, the shape of the precast structure 1 may not be a perfect circle, and may be another shape as long as an arch action can be used, such as an ellipse.

  For example, as shown in FIG. 3, the above-described lower segment 3a and upper segment 3b are made of solid concrete, but may have a hollow structure. The lower segment 3a and the upper segment 3b can achieve further weight reduction by making the inside hollow if the strength is sufficient. For example, with respect to compression and shearing of concrete, there is no problem even if it is hollow because there is room in the concrete cross section. On the other hand, with respect to concrete tension, it is only necessary to secure a member height (member thickness) as a concrete member that can arrange reinforcing bars that resist tension.

  In addition, as a method of making the inside of the lower segment 3a and the upper segment 3b hollow, for example, a member such as a foam may be disposed inside the lower segment 3a and the upper segment 3b, and the concrete may be made hollow. Alternatively, the concrete may be hollow by embedding a winding pipe in the lower segment 3a and the upper segment 3b. In any case, reinforcing bars are arranged at a predetermined interval in the concrete portion around the hollow portion so as to surround the hollow portion.

  Next, the construction method of an underground structure using the precast structure 1 will be described. Fig.5 (a) is a figure which shows the process of arrange | positioning and connecting the lower segment 3a. In the following description, illustration of Yamatome etc. is omitted. The lower segment 3a is laid below (underground) the excavation part 31.

  Here, when laying the lower segment 3a and the upper segment 3b, they are lifted by a crane or the like. Therefore, when the lower segment 3a and the upper segment 3b are lifted or laid, the openings of the lower segment 3a and the upper segment 3b may be opened and deformed.

  In the present embodiment, a reinforcing member is provided when the lower segment 3a and the upper segment 3b are lifted. FIG. 6 is a diagram showing the lower segment 3a and the upper segment 3b provided with the reinforcing members 29a and 29b.

  The reinforcing member 29a is provided on the inner surface side of the lower segment 3a and substantially at the center of the arc portion. That is, the reinforcing member 29a suppresses the opening of the lower segment 3a on the opening side. Similarly, the reinforcing member 29b is provided on the outer surface side of the upper segment 3b and substantially at the center of the arc portion. That is, the reinforcing member 29b suppresses the opening of the upper segment 3b on the opening side.

  The reinforcing members 29a and 29b can also be used as hanging positions when suspended by a crane or the like. By suspending the reinforcing portion in this way, deformation of the lower segment 3a and the upper segment 3b is suppressed, and the suspension is easy.

  The reinforcing members 29a and 29b are not limited to the example shown in FIG. For example, as shown in FIG. 7, you may provide so that each opening end vicinity of the lower segment 3a and the upper segment 3b may be connected. Even if it does in this way, the opening of the opening part of the lower segment 3a and the upper segment 3b can be suppressed.

  The reinforcing members 29a and 29b are detachable. For this reason, after installing the lower segment 3a and the upper segment 3b, the reinforcing members 29a and 29b can be removed and reused.

  Here, as shown in FIG. 5A, supporters 33 are arranged in the cut portion 31 at a predetermined interval. Therefore, the lower segment 3 a is suspended from the gap of the support 33 by the crane. A rail 35 is laid along the longitudinal direction of the cut portion 31 below the cut portion 31.

  The lower segment 3a arranged on the rail 35 can be moved by the winch 37 by the crane (in the direction of arrow H in the figure). Therefore, the lower segment 3a can be moved in the direction of the already installed lower segment 3a and connected in the longitudinal direction. At this time, the water stop members 9a and 9b are disposed between the lower segments 3a. As described above, since the guide protrusions 5 can first be used to position each other, subsequent tensioning by the tensioning member 15 is easy.

  When the connection of the lower segment 3a having a predetermined length is completed, the fluidized soil 39 is filled around the lower segment 3a as shown in FIG. 5 (b).

  FIG. 8 is a cross-sectional view taken along the line II of FIG. As described above, since the lower segment 3a has a circular arc shape, the gap with the bottom surface of the cut portion 31 is large, and the fluidized soil 39 can be easily filled. At this time, the fluidized soil 39 is also filled with a predetermined amount of fluidized soil 39 in the lower segment 3a. By doing in this way, the lower segment 3a (precast structure) can be prevented from being lifted, and a scaffold in the lower segment 3a can be secured. At least a part of the lower segment 3 a installed in this way is backfilled with the fluidized soil 39.

  Next, as shown in FIG. 9A, the upper segment 3b is suspended. At this time, as shown in FIG. 9B, a rail 35 is laid on the fluidized soil 39 inside the lower segment 3 a, and a gantry 41 is further installed on the rail 35. Therefore, the gantry 41 is movable along the rail 35 in the longitudinal direction of the cut portion 31.

  When the upper segment 3b is suspended on the gantry 41 by the crane, the gantry 41 on which the upper segment 3b is placed is moved by the winch 37 in the direction of the already installed upper segment 3b, and the lower segments 3a are moved in the longitudinal direction. Can be linked to. At this time, the water stop members 9a and 9b are disposed between the upper segments 3b. As described above, since the guide protrusions 5 can be positioned with respect to each other, subsequent tension by the tension member 15 is easy.

  The upper segment 3b is connected to the lower segment 3a. Under the present circumstances, the water stop members 9c and 9d are arrange | positioned between the lower segment 3a and the upper segment 3b. Thus, the precast structure 1 is constructed by connecting the lower segment 3a and the upper segment 3b in the circumferential direction and the longitudinal direction.

  FIG. 10 is a diagram showing the underground structure 43 constructed as described above. In addition, although the underground structure 43 shows the example which is an underground tunnel, if it is a structure constructed | assembled underground, such as a water and sewage storage part and an underground parking lot, it is applicable to all.

  When the underground structure 43 is an underground tunnel, a part of the precast structure 1 is exposed to the ground. That is, the underground structure 43 is one in which at least a part of the precast structure 1 is buried underground.

  11A is a cross-sectional view taken along line JJ in FIG. 10, FIG. 11B is a cross-sectional view taken along line KK in FIG. 10, and FIG. 11C is a cross-sectional view taken along line LL in FIG. It is.

  As shown to Fig.11 (a), in a basement part, a pair of precast structure 1 is adjoined, for example. Further, a part of the precast structure 1 is embedded in the fluidized soil 39.

  Further, near the ground of the underground tunnel, a part of the precast structure 1 may be opened as shown in FIG. That is, you may form the opening part 45 which a part of substantially circular precast structure 1 opened in the state which connected the lower segment 3a and the upper segment 3b in the circumferential direction. For example, as the upper segment 3b connected in the longitudinal direction, a completely semicircular shape and a 1/4 circular shape with a quarter circle cut off may be alternately connected. By doing in this way, the ground and the inside of an underground tunnel can be connected.

  On the side closer to the ground of the underground tunnel, a part of the precast structure 1 may be further opened as shown in FIG. That is, a part of the precast structure 1 may be configured by only the lower segment 3a, and the semicircular opening 45 may be formed above. By doing in this way, it can connect easily with a land road etc.

  Thus, in the underground structure 43 of the present embodiment, a part of the cross section in the longitudinal direction of the precast structure 1 constructed by the lower segment 3a and the upper segment 3b is substantially circular, and the other part of the cross section However, it can be made into the shape which a part of substantially circular opened.

  Next, a method for constructing a submarine tunnel will be described. FIG. 1 is a schematic cross-sectional view of the tunnel 51 in the longitudinal direction. The tunnel 51 is configured by connecting a submarine tunnel portion 53 and a land tunnel portion 55.

  The seabed tunnel portion 53 is buried under the seabed 61. The submarine tunnel portion 53 and the land tunnel portion 55 are connected by a connection portion 59. The connection part 59 serves as a ventilation tower, for example. The tunnel 51 of the present invention is configured by connecting at least a submarine tunnel portion 53 with a plurality of precast structures 57. Note that the precast structure 57 may have a substantially circular shape, or may have a form in which a plurality of circular cross sections are connected.

  The precast structure 57 is embedded in the seabed 61. For example, the precast structure 57 is buried with crushed stone. In this case, after excavating the seabed 61 to a predetermined depth, the crushed stone is disposed with a predetermined thickness, and the precast structure 57 is sunk thereon, and then the entire precast structure 57 is buried with the crushed stone. Moreover, you may perform ground improvement with respect to the lower ground which lays a crushed stone as needed.

  Next, the construction method of the tunnel 51 will be described in detail. First, as shown in FIG. 13, a steel pipe sheet pile cylinder 79 is constructed between a submarine tunnel construction range 53 a where the submarine tunnel portion 53 is constructed and a land tunnel construction range 55 a where the land tunnel portion 55 is constructed. The steel pipe sheet pile cylinder 79 is formed by connecting a plurality of steel pipe sheet piles 81. The steel pipe sheet pile cylinder 79 is formed deeper than the connection part between the submarine tunnel part 53 and the land tunnel part 55.

  Here, for example, a joint structure as disclosed in Japanese Patent Application Laid-Open No. 2011-001767 can be applied to the connecting portion between the steel pipe sheet piles 81. That is, a pair of first L-shaped members joined inward to each other on the side of the steel pipe main body are provided, and the other side of another adjacent steel pipe main body is mutually fitted so as to fit the first L-shaped member. Providing a pair of second L-shaped members joined outward, placing concrete in a space surrounded by the pair of first L-shaped members and the pair of second L-shaped members; The steel pipe sheet piles 81 are connected to each other.

  The inner ground surrounded by the steel pipe sheet pile cylinder 79 is excavated, and the bottom plate 83 is constructed to a predetermined depth. The bottom plate 83 is a part where a connection portion between the submarine tunnel portion 53 and the land tunnel portion 55 is constructed. That is, the bottom plate 83 is formed at a position deeper than a portion where the submarine tunnel portion 53 and the land tunnel portion 55 are connected.

  Next, as shown in FIG. 14A, a production yard 89 is constructed in a predetermined range of a land tunnel construction range 55a that is on the land side of the steel pipe sheet pile cylinder 79. The production yard 89 is formed by excavating part of the ground in the land tunnel construction range 55a. If the depth of the production yard 89 is lower than the water surface, it is not necessary to cut to the depth for constructing the land tunnel. That is, the production yard 89 may be formed using the entire land tunnel construction range 55a, or may be formed in a range smaller than the land tunnel construction range 55a using only a part of the land tunnel construction range 55a. Also good. The above-described construction of the bottom plate 83 may be performed simultaneously with the construction of the production yard 89.

  The production yard 89 is formed up to the steel pipe sheet pile cylinder 79. On the side surface of the production yard 89, a mountain stop 87 is provided. That is, the pile 87 is joined to the steel pipe sheet pile cylinder 79. Further, a part of the steel pipe sheet pile cylinder 79 is cut out to form a passage of a precast structure 57 described later. That is, the production yard 89 communicates with the sea. In addition, since the gate 85 is formed in the surface facing the sea of the steel pipe sheet pile cylinder 79, it is prevented that seawater flows into the production yard 89 on the land side of the gate 85.

  In addition, although the gate 85 was formed in the side surface which faced the sea of the steel pipe sheet pile cylinder 79, another site | part may be sufficient. That is, the gate 85 may be formed on the other side surface (land side surface) of the steel pipe sheet pile cylinder 79 or formed in the ground excavation part as long as the assembly place of the precast structure 57 in the production yard 89 can be secured. May be.

  Next, as shown in FIG. 15A, a precast structure 57 is assembled in a production yard 89 that functions as a dry dog. For example, a ballast is provided inside the precast structure 57. Further, both end portions of the precast structure 57 are closed.

  When the assembly of the precast structure 57 is completed, as shown in FIG. 15B, the gate 85 is opened, and seawater is introduced into the production yard 89. The material of the gate 85 is, for example, iron or concrete (precast), and the gate 85 is opened and closed by a method of pulling up with a large heavy machine or a method of a temporary sluice gate.

  The precast structure 57 that has surfaced on the sea surface is towed to the sea side by a towing vessel (arrow O in the figure). That is, the precast structure 57 is towed and moved from the production yard 89 to the sea of the installation site. As shown in the figure, the gate 85 may not be moved up and down, but may be double open.

  The precast structure 57 towed to the sea is towed to the settling site. At this time, as described above, the seabed 61 where the precast structure 57 is set is excavated in advance to a predetermined depth, and crushed stone is laid as described above. The bottom where the seabed 61 is excavated and crushed stone is laid is defined as the seabed 61a. That is, the precast structure 57 is set on the seabed 61a.

  After the precast structure 57 is towed to the set place, water is introduced into the ballast, and the precast structure 57 is set. As described above, the precast structure 57 can be deposited on the seabed 61a at a desired location. The precast structure 57 installed at the end of the submarine tunnel is then connected to the connection 59. At this time, a part of the connecting portion 59 may be constructed on the bottom plate 83 by, for example, a caisson, except for the passage portion (upper part) of the precast structure 57, for example.

  The manufacturing, towing and setting of the precast structure 57 are repeated. After the plurality of precast structures 57 are deposited, adjacent precast structures 57 are connected to each other. In addition, any structure may be sufficient for the connection of the precast structures 57, as long as normal segments can be connected. Further, after all the precast structures 57 have passed through the portion of the steel pipe sheet pile cylinder 79, the connecting portion 59 is completed to the ground. Thus, the precast structure 57 can be used as a buried box.

  Here, the connection structure of the conventional box-shaped submerged box is provided with a flexible mechanism for absorbing surrounding deformation. On the other hand, a flexible mechanism is not necessary for the connecting portion between the precast structures 57 of the present invention. This is because the precast structure 57 of the present invention is composed of a large number of annular members (the lower segment 3a and the upper segment 3b), so that a slight displacement can be allowed at the connection portion between the annular members. is there. For example, the precast structure 57 of the present invention is configured by connecting 80 to 100 annular members in the longitudinal direction. Assuming that the flexible mechanism in the conventional connection structure allows deformation of about 100 mm, in the present invention, it is sufficient that the deformation can be permitted by being dispersed by about 1 mm at the connecting portions of the annular members. For this reason, a flexible mechanism becomes unnecessary in the connection part between submerged boxes.

  As a result, since the submerged tunnel using the precast structure 57 of the present invention has substantially constant rigidity in the longitudinal direction, a large rigidity change part is not formed at the connection part as in the conventional case, and stress is reduced. Concentration is also unlikely to occur.

  In order to connect the precast structures 57 to each other, a sealing member is sandwiched between the precast structures 57 and hydraulic bonding is performed. In the hydraulic pressure bonding, first, the precast structure 57 having the sealing member attached to the end face is attached to the other precast structure 57 and drawn by a drawing jack (not shown). At this time, the sealing member is compressed by the force of the pulling jack to obtain a water stop effect. Next, when the water surrounded by the end face of the precast structure 57 and the seal member is drained, an external water pressure and a differential pressure are generated on the opposite end face of the precast structure 57, and the seal member further increases the amount of compression, thereby ensuring safety. High water stopping effect is obtained.

  A secondary lining is placed on the inner surface of the precast structure 57 and the inner surface of the connecting portion. Thus, the connection between the precast structures 57 is completed. The subcast tunnel 57 is completed by sinking the precast structure 57 over the entire length of the submarine tunnel 53 to complete the joining and backfilling the precast structure 57.

  Thus, since the precast structure 57 is connected and configured, an arch shape can be easily formed in the cross section. Therefore, the resistance to external pressure is improved as compared with a box-type submerged box formed by spot casting in a dry dog as in the prior art. For this reason, thickness can be made thin.

  Further, as the production yard 89 for assembling the precast structure 57, the land tunnel construction range 55a is used. For this reason, the precast structure 57 can be assembled at a place close to the set place. Further, the production yard 89 formed by the excavation can be used as it is for the construction of the land tunnel portion 55 thereafter. Therefore, there is no waste and the tunnel 51 can be constructed efficiently.

  Next, the construction method of the land tunnel part 55 is demonstrated. The land-based tunnel portion 55 can be constructed by the above-described open-cut method, but can also be constructed as follows.

  First, almost the entire construction area of the land tunnel part 55 is excavated, and a production yard is newly constructed at, for example, the endmost part (the side far from the submarine tunnel part 53 and close to the ground surface). The newly constructed production yard is formed at a position lower than the sea level. A gate is provided at the sea side end of the production yard. The gate prevents seawater from flowing into the production yard. That is, seawater is introduced into the land tunnel construction area 55a outside the gate (sea side).

  In the production yard that functions as a dry dog by the gate, the precast structure 57 is assembled. When the assembly of the precast structure 57 is completed, the gate is opened and seawater is introduced into the production yard in the same manner as described above. The precast structure 57 that has surfaced on the water surface is towed to the sea by a towed ship. That is, the precast structure 57 is towed from the production yard to the settling site.

  After the precast structure 57 moves on the water to the place where the land tunnel construction area 55a is set, water is introduced into the ballast to set the precast structure 57. As described above, the precast structure 57 can be deposited at a desired place. Note that the precast structure 57 installed at the end of the land tunnel portion 55 is connected to the connection portion 59.

  The manufacturing, towing and setting of the precast structure 57 are repeated. After the plurality of precast structures 57 are deposited, adjacent precast structures 57 are connected to each other. The connection between the precast structures 57 is the same as the construction of the submarine tunnel portion 53.

  After all the precast structures 57 have been set, secondary lining is placed on the inner surface and the inner surface of the connecting portion. Thus, the connection between the precast structures 57 is completed. The precast structure 57 is deposited over the entire length of the land tunnel portion 55 to complete the joining, and the precast structure 57 is backfilled to complete the land tunnel portion 55.

  As described above, in the present invention, the land tunnel portion 55 can also be constructed by setting the precast structure 57. That is, the land tunnel portion 55 using the lower segment 3a and the upper segment 3b can be easily constructed even for the relatively shallow land tunnel portion 55 where the shield method cannot be used.

  Next, an example of an offshore floating structure using the precast structure 57 will be described. FIG. 16 is a diagram illustrating the offshore floating facility 91. As described above, both ends of the precast structure 57 are closed. For this reason, it can be floated on the ocean. When used as the offshore floating structure 90, a plurality of precast structures 57 are connected in a direction perpendicular to the longitudinal direction. In the illustrated example, two precast structures 57 are connected.

  On the offshore floating structure 90 constructed in this manner, an offshore floating equipment 91 such as an offshore windmill is installed. Thus, since the precast structure 57 is excellent in water-stopping property, it can also be used as the offshore floating structure 90.

  As mentioned above, although embodiment of this invention was described referring an accompanying drawing, the technical scope of this invention is not influenced by embodiment mentioned above. It is obvious for those skilled in the art that various modifications or modifications can be conceived within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

1, 57 ......... Precast structure 3a ......... Lower segment 3b ......... Upper segment 5 ......... Guide projection 5a ......... Hole 7 ......... Coupling projections 9a, 9b, 9c, 9d ......... Water stop member 11... Hole 13... Connection member 15... Tension member 17... Anchor plate 19... Coupler sleeve 21. , 29b ......... Reinforcing member 31 ......... Cut-off part 33 ......... Supporting work 35 ......... Rail 37 ......... Winch 39 ......... Fluidized soil 41 ......... Place 43 ......... Underground structure 45 ......... Opening 51 ......... Tunnel 53 ......... Submarine tunnel 53a ......... Submarine tunnel construction range 55 ......... Land tunnel portion 55a ......... Land tunnel construction range 59 ......... Connections 61, 61a ... ... Seabed 79 ... …… Steel sheet pile 81 ……… Steel sheet pile 83 ……… Bottom plate 85 ……… Gate 87 ……… Yamadome 89 ……… Manufacturing yard 90 ……… Offshore floating structure 91 ……… Offshore Floating body equipment

Claims (3)

A construction method for an underground structure,
Installing a segment having an arch shape at a predetermined position; and
A step b for connecting the segments in the circumferential direction and the longitudinal direction via a water stop member;
A step c of backfilling at least a part of the segment with fluidized soil;
Comprising
The outer peripheral surface of the segment is provided with a first protrusion as a positioning guide in the longitudinal connection between the segments,
The step b aligns the positions of the first protrusions of the segments adjacent in the longitudinal direction, and connects them with a connecting member penetrating the first protrusions.
Furthermore, the pre-stress is imparted by tensioning the segments adjacent in the longitudinal direction ,
In the step c, the construction method of an underground structure is characterized in that a predetermined amount of fluidized soil is also filled in the segment . In the step a, suppressing the reinforcing member is attached to the opening side of the segment is opened, after installing the segment, the construction method of claim 1 underground construction according to, characterized in that removing the said reinforcing member . Some of the cross-section of the longitudinal direction of the precast structures built by the segments is substantially circular, according to claim 1, wherein the other part of the cross section has a shape that a portion of the substantially circular and opened Or the construction method of the underground structure of Claim 2 .

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