JP2017206882A - Method of constructing underground structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of constructing an underground structure that can largely shorten the construction period and reduces the construction cost without using a precast member.SOLUTION: A part of an upper ground 1 between continuous underground walls 11a and 11b is excavated and a short strut 17 is installed. Next, the upper ground 1 between the continuous underground walls 11a and 11b is excavated to a predetermined depth and is excavated, for example, to a depth permitting installation of a form of a pile cap. The short strut 17 may be one that can resist an earth pressure up to the depth. An upper surface of an excavated part is smoothly finished and is rolled so as not to settle, and crushed stones are laid and leveled. Next, sand is evenly laid on the surface and leveled, and a form 19 is installed. Next, a reinforcement 22 is assembled on the form 19. Concrete is also placed so as to fill up the reinforcement 22, and a pile cap 21 is formed on the ground between the pair of continuous underground walls 11a and 11b.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a method for constructing an underground structure such as an underground tunnel.

  In recent years, there are increasing plans to construct underground tunnels for passing traffic directly under existing roads in urban road maintenance works and the like. Normally, the open-cut method is used when the ground cover of the planned underground tunnel is shallow. In the open-cut method, a retaining wall is first constructed outside the underground tunnel frame, and an intermediate pile is placed inside. Then, a road surface lining is installed, water is stopped and the bottom is improved as necessary, and the tunnel construction space is excavated while installing the beams. Afterwards, cast concrete is cast in the excavated tunnel construction space from the bottom in order to construct the tunnel frame.

  Moreover, in order to shorten a construction period compared with a general cutting method, there is also a method of constructing an underground tunnel using precast concrete (Patent Document 1).

JP2015-117545A

  Although it is possible to shorten the construction period by using a precast member as in Patent Document 1, depending on the construction site, it may be difficult to transport a large precast member, or the place where the material is placed. It may be difficult to ensure. Therefore, a construction method that can shorten the construction period by using cast-in-place concrete is also desired.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a method for constructing an underground structure that can significantly reduce the work period and cost without using a precast member.

  The present invention for achieving the above-described object includes a step a for constructing a continuous underground wall in the ground, a step b for constructing a top plate on the ground between a pair of the continuous underground walls, and the continuous A step c of excavating a space surrounded by the underground wall and the top plate in a longitudinal direction of an underground structure, and a step of constructing a bottom plate at the bottom of the space surrounded by the continuous underground wall and the top plate d), and a construction method of an underground structure.

  It is desirable to provide a step e between the step a and the step b, in which a ground improvement portion is constructed as an underground beam below a portion where the bottom plate is constructed.

  The step e is performed by high-pressure jet agitation, and after the step b, before the step c or simultaneously with the step c, using the slime generated by the high-pressure jet agitation, A backfilling step f may be provided.

  The step a may be performed using a steel continuous wall core member having a temporary core member at the top, and the temporary core member may be removed after the step b.

  The step b includes excavating a predetermined depth between the pair of continuous underground walls, placing a formwork on the ground between the pair of continuous underground walls, and placing the top plate on the formwork. After the step c, the formwork may be removed from the underground structure.

  According to the present invention, since the top plate is first constructed, there is no need for a support work or a beam as in the prior art. In addition, the ground can be used without waiting for the completion of the internal excavation and bottom plate construction processes. For this reason, it is possible to shorten the period for carrying out ground traffic regulation associated with the construction of underground structures.

  Moreover, since internal excavation and bottom plate construction are performed after the top plate is constructed, noise on the ground can be suppressed. In addition, by installing the top plate first, it is possible to reduce work at high places as compared with the case where top plate construction is performed after excavation inside the underground structure. For example, when placing the concrete of the top plate, the top plate can be supported by the ground, so that high-level work such as installation of a mold is not necessary. For this reason, safety can be improved and a construction period can be shortened.

  In addition, by constructing underground beams by improving the ground at the bottom of the bottom plate construction part, the continuous underground wall can be supported by the top plate and underground beams even for soft ground, and the inside of the underground structure During excavation, it is possible to reduce the conventional support work and installation of beams.

  Further, by forming the underground beam by high-pressure jet stirring and using the slime generated by the high-pressure jet stirring to backfill the upper part of the top plate, it is possible to reduce the cost of processing the slime.

  Moreover, the continuous underground wall is formed using the steel continuous wall core material having the temporary core material at the upper part, and the temporary core material is removed when the upper part of the top plate is backfilled.

  Moreover, the bottom of the top plate can be constructed with high accuracy by arranging the mold on the ground between the pair of continuous underground walls and constructing the top on the mold. At this time, since the ground receives the load of the top plate, the formwork does not require strength. Moreover, after excavation inside the underground structure, the formwork can be easily removed by removing the formwork from the tunnel.

  ADVANTAGE OF THE INVENTION According to this invention, the construction method of the underground structure which can aim at a significant shortening of a construction period and a construction cost reduction can be provided, without using a precast member.

The figure which shows the process of incorporating steel continuous wall core material 7a, 7b. The figure which shows the process of constructing the continuous underground wall 11a, 11b. The figure which shows the process of forming the ground improvement part. The figure which shows the process of installing the upper beam 17. FIG. The figure which shows the process of excavating a part of upper part. The figure which shows the process of constructing the top plate. The figure which shows the process of refilling the upper part of the top plate. The figure which shows the process of excavating the lower part of the top plate 21, and constructing the bottom plate 25. FIG. The figure which shows the underground structure 30. The figure which shows the process of constructing the underground structure 30 in order.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1-10 is a figure which shows the construction method of the underground tunnel concerning this Embodiment. Unless otherwise specified, (a) in each drawing is a plan view and (b) is a cross-sectional view.

  First, the land boundaries A and C are divided into a work area D (between AB) and a cut-off road E (between BC), and a guide wall 3 is installed in the work area. The following work is performed in the work area D, and the cut-off road E can be used as a roadway.

  In the installation part of the guide wall 3, the ground 1 is excavated by a continuous underground wall excavator to form a continuous underground wall hole wall 5, and the inside is stabilized with a stabilizing liquid. Furthermore, steel continuous wall core materials 7a and 7b are built into the continuous underground wall hole wall 5 by a crane (arrow F in the figure). An upper temporary core material 9 is provided on the upper part of the steel continuous wall core materials 7a and 7b. The upper temporary core material 9 can be removed from the steel continuous wall core materials 7a and 7b.

  Next, as shown in FIGS. 2 (a) and 2 (b), concrete is cast on each continuous underground wall hole wall 5 to form a pair of continuous underground walls 11a and 11b (side walls). . First, the steel continuous wall core 7a may be built to construct the continuous underground wall 11a, and then the steel continuous wall core 7b may be built to construct the continuous underground wall 11b. The concrete is cast to a position below the upper temporary core material 9.

  Next, the upper portions of the continuous underground walls 11a and 11b are backfilled with sand or the like. Under the present circumstances, the earth retaining plate 10 is installed in the upper part of the continuous underground wall 11b of the center part of the site boundary AC on the outer side (the cut road side) of the upper temporary core material 9.

  Next, as shown in FIGS. 3A and 3B, a ground improvement portion 15 is provided between the lower portions of the continuous underground walls 11a and 11b. The ground improvement part 15 is formed in the lower part of the bottom plate construction part mentioned later, and functions as a preceding underground beam.

  The ground improvement part 15 is formed by high-pressure jet stirring, for example. In this case, slime pits 13 are provided at predetermined intervals, and the ground improvement portion 15 is formed in the slime pits 13 using a ground improvement construction machine. At this time, it is desirable that the ground improvement portion 15 is formed without a gap between the continuous underground walls 11a and 11b. The ground improvement part 15 may be formed by chemical injection or the like. Moreover, when the ground 1 has sufficient strength, the ground improvement unit 15 is not necessarily required.

  Next, as shown in FIGS. 4 (a) and 4 (b), a part of the ground 1 at the upper part (between the upper temporary core members 9) between the continuous underground walls 11a and 11b is excavated and cut. The beam 17 is installed (arrow G in the figure). The cut beam 17 is installed between the upper temporary core materials 9. In this case, a part of the cut road is used as a work area.

  Next, as shown in FIGS. 5A and 5B, the ground 1 at the upper part (between the upper temporary core materials 9) between the continuous underground walls 11a and 11b is excavated to a predetermined depth. For example, excavation is performed to a depth where the formwork of the top plate can be installed. The cut beam 17 may be capable of withstanding earth pressure up to this depth. Moreover, if the upper temporary core material 9 etc. can withstand earth pressure, the cut beam 17 is not necessarily required.

  The upper surface of the excavation part is finished smoothly and pressed so as not to sink, and crushed stone is leveled. Next, sand is spread on the surface to make it smooth, and the mold 19 is installed.

  Next, as shown in FIGS. 6A and 6B, the reinforcing bars 22 are assembled on the mold 19. The ends of the reinforcing bars 22 are integrated with the steel continuous wall cores 7a and 7b by welding or the like.

  Furthermore, concrete is cast so that the reinforcing bars 22 are buried, and the top plate 21 is formed on the ground between the pair of continuous underground walls 11a and 11b. In addition, since the weight of the top plate 21 is supported by the ground, the above-described mold frame 19 does not require strength. After the concrete of the top plate 21 is cured, waterproofing is performed as necessary. Moreover, the bolt which fixes the upper temporary core material 9 on the continuous underground wall 11a is removed, and it is set as the state which can remove the upper temporary core material 9. FIG.

  Next, as shown in FIGS. 7A and 7B, the upper part of the top plate 21 is backfilled to the ground surface. Moreover, the upper temporary core material 9 on the continuous underground wall 11a is removed (arrow H in the figure). In addition, when the ground improvement part 15 mentioned above is performed by high-pressure jet stirring, the generated soil is mixed with the slime generated by high-pressure jet stirring to make fluidized treated soil, and this is used to fill the upper part of the top plate 21. You may return.

  When the upper part of the top plate 21 is backfilled, the land boundary AC can be used as a road.

  Next, as shown in the sectional view of FIG. 8A, a space surrounded by the continuous underground walls 11a and 11b and the top plate 21 is excavated (arrow I in the figure). The excavation is performed with a backhoe or the like, and is excavated in the longitudinal direction of the underground structure. At this time, the mold 19 is removed from the tunnel. By the mold 19, the lower surface of the top plate 21 is applied smoothly.

  When excavation to the ground improvement part 15 is completed, as shown in FIG. 8 (b), the leveling concrete 23 is placed on the ground improvement part 15 to make it flat, and a reinforcing bar is assembled on the leveling concrete 23 to put the concrete. The bottom slab 25 is installed. That is, the bottom plate 25 is constructed at the bottom of the space surrounded by the continuous underground walls 11 a and 11 b and the top plate 21.

  From this state, the land boundary AC is divided into a work area D (between BC) and a cut-off road E (between AB). In the work area, a tunnel is further constructed in the same process as described above.

  FIG. 9 is a cross-sectional view showing the underground structure 30 (underground tunnel) formed in this way. In addition, after forming the top plate 21 between the continuous underground walls 11b and 11c, the upper temporary core material 9 of the continuous underground walls 11b and 11c is each removed. Moreover, the underground structure 30 is constructed by pavement and interior work inside the tunnel.

  FIG. 10 is a diagram showing a state in which the above steps are performed simultaneously. In FIG. 10, construction is performed in order from the right side, and an underground tunnel is constructed.

  The state of the J position in FIG. 10 is a position corresponding to FIG. That is, it is the state where the continuous underground wall hole wall 5 was constructed. Similarly, the state of the K position in FIG. 10 is a position corresponding to FIG. That is, it is the state where the continuous underground walls 11a and 11b were constructed.

  The state of the L position in FIG. 10 is a position corresponding to FIG. That is, it is the state where the ground improvement part 15 was constructed. The state of the M position in FIG. 10 is a position corresponding to FIG. That is, it is a state where the cutting beam 17 is installed.

  The state of the N position in FIG. 10 is a position corresponding to FIG. That is, it is the state excavated to the upper part of continuous underground wall 11a, 11b. The state at the O position in FIG. 10 is a position corresponding to FIG. That is, the top plate 21 is in a state of being constructed.

  The state of the P position in FIG. 10 is a position corresponding to FIG. That is, the top plate 21 is backfilled. The state of the Q position in FIG. 10 is a position corresponding to FIG. That is, the lower part of the top plate 21 is excavated. In addition, the excavated generated soil is carried out from the right well entrance in the figure.

  The state of the R position in FIG. 10 is a position corresponding to FIG. That is, the bottom slab 25 is constructed by assembling the reinforcing bars 26 on the leveling concrete 23 arranged on the ground improvement portion 15.

  As described above, each process can be performed simultaneously in each part of the tunnel. For example, the step of backfilling the top plate 21 and the step of excavating the lower portion of the top plate 21 may be performed simultaneously.

  As described above, according to the present embodiment, when excavating inside the tunnel, the surface portion can be used as a road, so that the underground structure 30 can be efficiently constructed, and the construction period can be greatly reduced and the construction cost can be reduced. it can. Moreover, since the use period of the surface part is short, the environmental load on the neighborhood can be reduced. For example, in FIG. 10, the work area in the ground surface can be eliminated during the process after the P state. In particular, the use period for the underpass and the like is effective because the ground surface is used for a short period of time and can be turned around.

  Moreover, since earth pressure is supported by the continuous underground walls 11a and 11b, the top plate 21, and the ground improvement part 15, the excavation inside a tunnel can reduce installation of a support work and a beam. For this reason, a construction period can be shortened.

  In addition, no formwork support is used to construct the top plate 21, and work can be performed safely because there is little work at high places. Moreover, since the formwork 19 for the top plate 21 is only for the purpose of smoothing the lower surface of the top plate 21, strength is not required.

  When the ground improvement part 15 is formed by high-pressure jet stirring, the amount of slime discarded can be reduced by backfilling the upper part of the top plate 21 using slime generated by high-pressure jet stirring.

  Moreover, by making it possible to remove the upper temporary core material, unnecessary earth retaining walls do not remain in the ground after tunnel construction.

  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.

DESCRIPTION OF SYMBOLS 1 ......... Ground 3 ......... Guide wall 5 ......... Continuous underground wall hole wall 7a, 7b ......... Steel continuous wall core material 9 ......... Upper temporary core material 10 ......... Dust plate 11a, 11b, 11c …… Continuous underground wall 13 ……… Slime pit 15 ……… Ground improvement part 17 ……… Cut beam 19 ……… Formwork 21 ……… Top plate 22 ……… Rebar 23 ……… Leveling concrete 25 ………… Bottom plate 26 ………… Rebar 30 ……… Underground structure

Claims (5)

Constructing a continuous underground wall in the ground; and
A step b of installing a top plate on the ground between the pair of continuous underground walls;
A step c of excavating a space surrounded by the continuous underground wall and the top plate in a longitudinal direction of an underground structure;
A step d of constructing a bottom plate at the bottom of the space surrounded by the continuous underground wall and the top plate;
The construction method of the underground structure characterized by comprising.   The construction of an underground structure according to claim 1, further comprising a step (e) of constructing a ground improvement portion as an underground beam between the step (a) and the step (b). Method.   The step e is performed by high-pressure jet agitation, and after the step b, before the step c or simultaneously with the step c, using the slime generated by the high-pressure jet agitation, The method for constructing an underground structure according to claim 2, further comprising a step (f) of backfilling. The step a is performed using a steel continuous wall core material having a temporary core material at the top,
The method for constructing an underground structure according to any one of claims 1 to 3, wherein the temporary core material is removed after the step b. The step b includes excavating a predetermined depth between the pair of continuous underground walls, placing a formwork on the ground between the pair of continuous underground walls, and placing the top plate on the formwork. Construct,
The method for constructing an underground structure according to any one of claims 1 to 4, wherein the formwork is removed from the underground structure after the step c.

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