JP5465086B2 - Construction method of underground structure - Google Patents

Description

  The present invention relates to a construction method for an underground structure obtained by improving the reverse winding method for constructing an underground structure in order from the top as the ground is excavated.

  The construction method of the underground structure is to dig a ground support structure made up of erections, beams, etc. inside the retaining wall, excavate the ground surrounded by the retaining wall to the floor, The so-called forward-winding method that builds the underground structure upward from the slab and the retaining wall, and the installation and excavation of the support structure from the top are repeated in advance to construct the ceiling slab of the underground structure. And what is called a reverse winding method etc. which construct a side wall and a floor slab in order toward the downward direction are known.

  In addition, a caisson method that constructs a concrete or steel caisson in a separate yard or factory in advance, transports it to the construction yard, and sinks the caisson while excavating the ground by manual or mechanical excavation ( Pneumatic caisson, submersible caisson, pressure caisson, etc.) are also known.

  The above-mentioned forward winding method has the merit that it is excellent in work efficiency because it constructs the underground structure after excavating to flooring and forming a wide construction space, but for the underground structure During bar arrangement work, problems such as the erection and cutting beams that make up the support work often interfere with this work, and this support work becomes an obstacle to the waterproof construction provided on the walls of underground structures. Such a problem has become apparent.

  In addition, since the construction of the ceiling slab is the last of the underground structures, the work of backfilling the excavated residual soil above the ceiling slab must be the last of the process, and the yard for the excavated residual soil is the first of the process. There is also a problem of being occupied by the remaining soil from the end to the end.

  By applying the reverse winding method described above to the problem of such a forward winding method, a support work is installed according to the ground excavation, and the construction of the underground structure is also performed in order from the top. Will not disturb the bar arrangement work and waterproofing work, and the ceiling slab will be built first in the underground structure, so the remaining soil can be backfilled early, and the remaining soil yard can be used for other purposes. It can be used effectively.

  However, when the reverse winding method is applied, in order to construct the side wall downward, there is a major problem that construction failure tends to occur at the joint of the side wall, and further, the underground structure constructed above For example, materials, construction machines, and construction materials are brought into a limited space between the ceiling slab and the excavation floor of the object, and further excavation and construction of underground structures are unavoidable in this space. There is a problem of being.

  In this way, the forward winding method and the reverse winding method have their own merits and demerits. For example, the reverse winding method has the inherent merits described above, so this reverse winding method is applied to underpass construction in Japan. First, the caisson method has been used frequently.

  Here, Patent Document 1 discloses a conventional published technique obtained by improving the reverse winding method. In this construction method, only the minimum necessary part of the 1st floor slab of the underground structure that can support the retaining wall is preliminarily constructed, and then excavation proceeds. Similarly, the underground 1st floor slab of the underground structure. Of these, only the minimum necessary part capable of supporting the earth retaining wall is preliminarily constructed, and this is repeated to complete the excavation up to the flooring and then build the underground structure upward.

  According to the construction method disclosed in Patent Document 1, since the side wall can be constructed from the bottom to the top, the problem of the reverse winding method described above, that is, the problem that the construction failure is likely to occur at the joint of the side wall is solved. I can. However, when constructing an underground structure from the bottom to the top, the floor slabs on each floor are divided into a preceding construction location used as a support construction and a subsequent construction location integrated with this preceding construction location. Therefore, since it is necessary to construct the floor slab of each floor twice, the construction efficiency is extremely poor and the construction period cannot be denied.

JP 11-280094 A

  The present invention has been made in view of the above-mentioned problems, and by improving the conventional so-called reverse winding method, it is possible to eliminate the problem that construction failure tends to occur at the joint of the side walls, and further, the construction period is lengthened. It aims at providing the construction method of the underground structure which does not let it.

  In order to achieve the above-mentioned object, the construction method of an underground structure according to the present invention is a first step of constructing a retaining wall at an opposing position in the ground, the ground surface with respect to the ground surrounded by the opposing retaining wall. The second step of installing excavation from both sides of the opposite retaining wall and installing a beam between the opposing uprights, further excavation, Build at least a ceiling slab, and support the retaining wall to the ceiling slab, and proceed with excavation to construct the flooring surface, build a leveled concrete slab on the flooring surface, And cutting the beams, constructing a floor slab on the leveled concrete slab, constructing the side wall upward, and constructing an underground structure consisting of at least the ceiling slab, the floor slab and the side wall , Is made up of.

  Here, “constructing the retaining wall at the opposite position” in the first step means that the retaining wall has a frame shape (endless shape) such as a rectangle, a square, other polygons, a circle, or an ellipse in plan view. This means that two or three or more pairs of earth retaining walls are formed. For example, in the case of a rectangular retaining wall in plan view, there is a pair of opposing retaining walls with a long side and a pair of opposing retaining walls with a short side.

  The form of the earth retaining wall to be constructed may be an underground continuous wall, a columnar continuous wall, a steel sheet pile, a main pile horizontal sheet pile, a steel pipe sheet pile, or the like. Moreover, you may perform ground improvement to the desired depth area | region of a retaining wall as needed.

  After construction of the retaining wall, proceed with excavation from the surface of the earth, install upset and cut beams between the opposing retaining walls, and proceed with further excavation to construct at least a ceiling slab that constitutes the underground structure. Support the retaining wall with a ceiling slab.

  Here, the erection and the cutting beam constructed above the ceiling slab may be one stage or a plurality of stages.

  In addition, the ceiling slab, which is a component of the constructed underground structure, may be any of an RC structure, an SRC structure, and an SC structure, and the tension material embedded in the concrete is a reinforcing bar, a PC steel (PC) Any of a combination of steel bars, PC steel wires, PC steel strands), reinforcing bars and PC steel materials may be used.

  Since the ceiling slab to be built supports the retaining wall, this ceiling slab can be regarded as a cut beam, and it is possible to eliminate the need for a cut beam that should be installed at this ceiling slab position, thereby reducing the construction cost required for temporary construction. can do. In the construction method of the present invention, all the ceiling slabs are constructed as underground structures at this stage.

  Here, the retaining wall is provided with a pre-embedded divel in the underground structure in advance, and in the third step, at least the ceiling slab is constructed while winding the gibel, thereby retaining the retaining wall. The relative displacement of the ceiling slab is suppressed, and the ceiling slab can effectively suppress the deformation of the retaining wall to the excavation side. Furthermore, a rigid portal ramen structure consisting of a retaining wall and a ceiling slab can be formed via a gibber, and the bending of the ceiling slab as much as possible after the excavated soil is backfilled on this ceiling slab is made as much as possible. Can be reduced.

  After supporting the retaining wall with at least the ceiling slab, proceed with excavation to construct the flooring surface, build a leveled concrete slab on the flooring surface, remove the flank and the cut beam, level By constructing a floor slab on the concrete slab and constructing the side walls upward, an underground structure composed of at least a ceiling slab, a floor slab, and a side wall is constructed. Here, “an underground structure consisting of at least a ceiling slab, a floor slab, and a side wall” means a ceiling slab and a floor slab (floor slab on the lowest floor) in addition to an underground structure consisting only of these components. It is meant to include underground structures having a plurality of floor slabs between them, and underground structures having walls and pillars on each floor.

  By constructing a leveled concrete slab, this is regarded as an earth pressure load-bearing member, and a retaining wall is supported by the leveled concrete slab and the ceiling slab. And all of the beams can be removed. In considering the leveled concrete slab as an earth pressure load bearing member, reinforcing bars, mesh bars, etc. may be provided in the leveled concrete slab as necessary.

  When all of the erection and the beam between the ceiling slab and the leveled concrete slab are removed, a floor slab is constructed on the leveled concrete slab, and a side wall is raised upward from the floor slab. That is, it differs greatly from the conventional reverse winding method in that the side walls are constructed from the bottom to the top.

  According to the construction method of the present invention in which the conventional reverse winding method is improved, since the side wall is constructed from the lower side to the upper side as in the forward winding method, it is difficult to cause poor construction at the joint of the side wall.

  In addition, the ceiling slab, floor slab, etc. that make up the underground structure are constructed at once in the construction stage of the underground structure. The problem of longevity cannot occur.

  In addition, when the floor slab is divided into two parts as in the conventional open technology, the prior construction is performed to ensure the integration of the joint part of the preceding construction part and the subsequent construction part and the securing of water stoppage. Since additional construction such as roughening construction or water stop construction at the joint portion of the location is unavoidable, these additional constructions also cause the construction period to be prolonged and the construction cost to increase.

  Further, in a preferred embodiment of the method for constructing an underground structure according to the present invention, a part of the side wall is constructed in addition to the ceiling slab, and a separate beam is installed between a part of the opposite side walls to perform preloading. It is to be introduced.

  In addition to applying the ceiling slab of the underground structure as a support for the retaining wall, the embodiment of this construction method is constructed such that a part of the side wall is constructed integrally with the ceiling slab, and the opposite side wall A beam is installed between a part of the beam, and a desired preload is introduced into the beam to provide a support work.

  According to the construction method of the present embodiment, the two-stage beam is substantially installed between the retaining walls from the ceiling slab constituting the underground structure and the beam between a part of the side walls. Become.

  Here, when setting the preload to be introduced, a strain gauge is arranged in advance on the ceiling slab (for example, a strain gauge is installed on the slab reinforcing bar), and this preload is referred to by referring to the measurement data from the strain gauge. It is preferable to set. By setting the introduction preload in this way, it is possible to effectively suppress the displacement of the ground around the retaining wall due to excavation, and at the same time, ceiling slabs and side walls that are components of the already constructed underground structure Residual stresses and cracks that can occur in a part of the surface can be controlled to a minimum.

  Note that the erection and the removal of the beam above the ceiling slab can be performed after the ceiling slab is constructed or after a preload is introduced into a separate beam.

  Then, after the uplift and the cut beam above the ceiling slab are removed, the backfilling of excavated residual soil and the like is performed above the ceiling slab, so that the remaining soil yard can be effectively used. Furthermore, this remaining soil treatment can be carried out at an early stage, which leads to shortening of the construction period.

  As can be understood from the above description, according to the construction method of an underground structure of the present invention, the ceiling slab constituting the underground structure is applied as a cut beam in the construction stage, and the side wall is directed upward from below. Thus, the temporary cost can be reduced and it is possible to make it difficult to cause a construction failure at the joint of the side walls. Furthermore, in the construction process of the underground structure, the construction members are not divided into two parts, so that the construction period is not prolonged and the construction cost is not increased.

It is the figure explaining the 1st process of the construction method of the underground structure of the present invention. FIG. 2 is a diagram for explaining a second step following FIG. 1. FIG. 3 is a diagram for explaining a third step following FIG. 2. FIG. 4 is a diagram for explaining a third step as in FIG. 3. FIG. 5 is a diagram for explaining a fourth step following FIG. 4. FIG. 6 is a diagram for explaining a fourth step as in FIG. 5. FIG. 7 is a diagram for explaining a fourth step, similar to FIG. 6. FIG. 8 is a diagram for explaining a fourth step, similar to FIG. 7. It is the figure explaining the 4th process like FIG. It is the figure explaining the 4th process like FIG.

  Hereinafter, the construction method of the underground structure of the present invention will be described with reference to the drawings. Although the illustrated underground structure is composed of a ceiling slab, a floor slab, and a side wall, the underground structure constructed by the construction method of the present invention is not limited to the illustrated example. Underground structures with various structural forms, such as those with multiple floor slabs between the ceiling slab and floor slab (bottom floor slab) and those with walls and pillars on each floor Things are the object of construction. Moreover, the method of constructing | assembling only the ceiling slab first in this underground structure and supporting a retaining wall by this, and constructing | assembling all the side walls after floor slab construction may be sufficient.

  FIGS. 1-10 is the figure explaining the 1st process-the 4th process of the construction method of the underground structure of this invention in order, More specifically, FIG. 2 illustrates the second step, FIGS. 3 and 4 illustrate the third step, and FIGS. 5 to 10 illustrate the fourth step.

  In the construction method of the present invention, as shown in FIG. 1, first, a retaining wall 1 having a rectangular shape in plan view is constructed in the ground G in a construction yard using a dedicated excavator M1. Here, the form of the retaining wall 1 is appropriately selected according to soil properties, groundwater level, flooring depth of underground structure, construction cost, construction period, etc., but the underground continuous wall and columnar continuous wall, Any of a steel sheet pile, a main pile horizontal sheet pile, a steel pipe sheet pile, etc. may be sufficient. In the illustrated example, an underground continuous wall is applied, and the retaining wall 1 is embedded in the support ground G1 below the original ground G.

  In the rectangular retaining wall 1 in plan view, FIG. 1 shows the retaining walls 1 and 1 disposed at a pair of opposing positions, and in the meantime, post-constructed cut beams are retained. A plurality of intermediate piles 2 are installed to support the intermediate positions between the walls 1 and 1 and to support a heavy machinery passage for temporary installation.

  When the earth retaining walls 1 and 1 are constructed at positions facing each other in the original ground G, as shown in FIG. 2, the ground improvement body 3 is constructed in the rooting area using the heavy equipment M2 for creation, and the groundwater wraps around. Take measures such as suppressing wall swelling and increasing the passive earth pressure of the retaining wall. Furthermore, ground water in the ground G surrounded by the rectangular retaining wall 1 having a rectangular shape in plan view is pumped (X1 direction), and excavation of the ground G is advanced using the backhoe M3.

  At the stage where excavation has progressed about 1 to 2 m in depth from the ground surface, the uplift 4A, 4A, which is the first stage support, is installed on both opposing earth retaining walls 1, 1, and this upset 4A , 4A through the intermediate pile 2 between the cut beams 5A.

  When the construction of the first stage beam 5A is completed, as shown in FIG. 3, the excavation of the ground is further advanced by using the bucket excavator M4, the backhoe M3, etc., and the excavation to the predetermined depth is completed. For example, the second stage beam 5B and the third stage beam 5C are suspended from the excavated ground surface.

  Then, the ceiling slab 11 of the underground structure and a part 12 'of the side wall are constructed so as to be continuous with the ceiling slab 11 of the underground structure below the first stage beam 5A that has already been installed. The retaining wall 1 is supported by the part 12 ′.

  Here, the earth retaining wall 1 is preliminarily extended with a not-illustrated divel, and the ceiling slab 11 and the side wall part 12 'are constructed so as to enclose the divel. A strong connection structure between the object constituent member and the earth retaining wall 1 can be formed. With this strong connection structure, the relative displacement between the ceiling slab 11 and the retaining wall 1 is suppressed, so that the deformation suppressing effect of the retaining wall 1 can be enhanced, and the surrounding of the retaining wall due to this can be improved. The effect of suppressing the deformation of the ground can also be enhanced.

  Next, as shown in FIG. 4, the raised beams 4B and 4B are installed inside the opposing side wall portions 12 'and 12', and the beams are already suspended between the raised portions 4B and 4B. 5B is installed, and a desired preload is introduced into this cut beam 5B.

  When this preload is introduced, a strain gauge (not shown) is installed in advance on the slab muscle constituting the ceiling slab 11, and the site manager sets the preload value by referring to the measurement data from the strain gauge. Good. By setting the introduction preload in this manner, the displacement of the ground around the retaining wall caused by excavation is effectively suppressed, and at the same time, the already constructed ceiling slab 11 and side wall part 12 ' Residual stresses and cracks that can occur can be controlled to a minimum.

  In the state shown in FIG. 4, the ceiling slab 11 supporting the retaining walls 1 and 1 facing each other can be regarded as a substantially high-rigidity beam, and the first-stage beam 5A and the ceiling slab 11 (substantially The second stage of the beam) and the beam 5B (substantially the third stage of the beam) spanned between the side wall portions 12 ', 12', The retaining walls 1 and 1 are supported. Therefore, compared to the conventional reverse winding method, in which three stages of cut beams were inevitably installed at this excavation stage, the installation of one stage of cut beams and uplifts is no longer necessary, resulting in a significant reduction in temporary costs. This can reduce the construction cost.

  If the retaining walls 1 and 1 are supported by substantially three-stage beams, as shown in FIG. 5, first, the first-stage beams 5A and the protuberance 4A that are no longer necessary for supporting the retaining walls are used. The excavation of the ground is further carried out, and the uplifted 4C that has already been hung is installed on both earth retaining walls 1 and 1, and the cut beam 5C is bridged between the uplifted 4C and 4C.

  In addition to the illustrated example, the first stage beam 5A and the erection 4A are removed after the retaining walls 1 and 1 are supported by the ceiling slab 11 shown in FIG. In addition, the removal timing of the first stage support is determined by the internal stress of the retaining wall 1 and the ceiling slab 11 determined at the removal timing, work efficiency, and the like.

  When the cut beam 5C is passed between the retaining walls 1 and 1, the ground is further excavated to form a flooring surface as shown in FIG. 6, and the leveled concrete slab 6 is constructed on the flooring surface. To do.

  In the leveled concrete slab 6, reinforcing bars, mesh bars, and the like are disposed, and these can be regarded as earth pressure load bearing members. That is, the leveled concrete slab 6 constructed between the retaining walls 1 and 1 has the same retaining wall supporting action as that of the cut beam.

  When the leveled concrete slab 6 is constructed between the retaining walls 1 and 1 as shown in FIG. 7, the lower ends of the retaining walls 1 and 1 are supported by this, and hung between the side walls 12 'and 12'. The cut beam 5B and the erection 4B which have been passed, and the lower beam 5C and the erection 4C below it are removed.

  By removing these support works, a wide work space is secured in the subsequent construction of the underground structure, and an efficient construction of the underground structure is guaranteed.

  Next, as shown in FIG. 8, the excavated residual soil left in the construction yard is backfilled on the ceiling slab 11 (backfill soil 7), and the floor slab 13 is constructed on the leveled concrete slab 6.

  In addition, the timing of the backfilling of the excavation residual soil on the ceiling slab 11 is not limited to the illustrated example, and can be the timing after removing the first stage support shown in FIG.

  When the construction of the floor slab 13 is completed, the construction of the side wall 12 is completed by constructing the remainder of the side wall from the bottom to the top as shown in FIG. And the underground structure 10 which consists of the ceiling slab 11, the floor slab 13, and the side wall 12 at least is constructed.

  The intermediate pile 2 is left over the top and bottom of the underground structure through the openings (not shown) provided in the ceiling slab 11 and the floor slab 13 as shown in FIG. In addition, by removing the portion that interferes with the underground structure 10 (the non-interfering portion 2 ′ is left as it is), the construction of the underground structure is completed by performing a filling process on an unillustrated opening.

  According to the construction method of the underground structure of the present invention shown in the figure, the conventional reverse winding method is improved to support the earth retaining wall on the ceiling slab, and further, a part of the side wall is constructed integrally with the ceiling retaining wall. By installing the desired beam and installing the desired preload, it is possible to reduce the number of steps of the support work, and more effectively suppress the deformation of the retaining wall and the surrounding ground deformation. .

  Moreover, since a side wall is constructed like a forward winding construction from the lower side to the upper side after the floor slab is constructed, it is possible to make it difficult to cause a construction failure at the joint of the side walls.

  Furthermore, since the earth retaining wall is supported by a high-stiffness ceiling slab, the first stage of the support work above the ceiling slab can be removed at an early stage, and the excavated residual soil can be quickly put on the ceiling slab. By backfilling, the remaining soil yard can be effectively used for another purpose.

  In addition, the unique effect that can be enjoyed when the reverse winding method is applied, that is, the support work can be performed efficiently because it does not interfere with the bar arrangement work and waterproof construction, and therefore the outer surface of the underground structure is highly waterproof. It goes without saying that the construction method of the present invention has effects such as quality assurance.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Earth retaining wall, 2 ... Intermediate pile, 2 '... Intermediate pile after cutting, 3 ... Ground improvement body, 4A, 4B, 4C ... Raised, 5A, 5B, 5C ... Cut beam, 6 ... Leveling concrete Slab, 7 ... Backfill soil, 10 ... Underground structure, 11 ... Ceiling slab, 12 ... Side wall, 12 '... Part of side wall, 13 ... Floor slab, G ... Original ground

Claims (6)

A first step of constructing a retaining wall at an opposing position in the ground;
Proceed with excavation from the ground surface against the ground surrounded by the opposite retaining wall, and install a bulge on both opposing retaining walls at a position higher than the position where the ceiling slab is constructed and face the opposite flank A second step of installing a cutting beam between
A third step of further excavation to construct at least a ceiling slab of the underground structure and to support a retaining wall on the ceiling slab;
Further advance the drilling, with the progress of the excavation by installing a further separate wale and Setsuhari below the ceiling slab construction the floor with surface, to build a concrete slab leveling on the floor with surface, ceiling The above-mentioned separate uplift and slab between the slab and the leveled concrete slab are removed , the leveled concrete slab is used as an earth pressure load bearing member, and the retaining wall is supported by the leveled concrete slab and the leveled concrete slab. A method for constructing an underground structure comprising a fourth step of constructing a floor slab on a slab, constructing a side wall upward, and constructing an underground structure composed of at least a ceiling slab, a floor slab and a sidewall.   2. The underground structure according to claim 1, wherein, in the third step, a part of the side wall is constructed in addition to the ceiling slab, and a preload is introduced by installing a separate beam between parts of the opposing side wall. How to build things.   The construction method of an underground structure according to claim 2, wherein a strain gauge is arranged on the ceiling slab, and a preload to be introduced to the cut beam is set with reference to measurement data obtained by the strain gauge. Wherein in the third step, after the ceiling slab is constructed, or after the preload it has been introduced into separate Setsuhari, the wale and Setsuhari lying above are removed than the ceiling slab, claim 2 or The construction method of the underground structure of 3 . The construction method of an underground structure according to claim 4 , wherein the backfilling operation is performed above the ceiling slab after the erection and the cut beam above the ceiling slab are removed. The said soil retaining wall is provided with a dowel which is embedded in the previously underground structures, in the third step, at least the ceiling slab is constructed with inclusion of the dowels, claim 1-5 Construction method of underground structure as described in 2.

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