JP7072483B2 - How to build a skeleton - Google Patents

Description

The present invention relates to a method for constructing a skeleton accompanied by erection of a replacement support.

In recent years, against the background of overcrowding of existing structures in urban areas, when trying to construct new roads, railways, etc., projects using deep underground spaces have been promoted. At that time, there is a concern about the influence of ground deformation on the existing structures in the vicinity, and there are many cases where strict restrictions are set on the amount of displacement of the mountain retaining wall. Regarding the skeleton construction work in the underground space under such circumstances, more advanced design and construction management is required for the skeleton construction after the excavation is completed and the accompanying removal of the Yamadome support work.
As a method of removing the Yamadome support, the inner beam replacement method has been adopted and has abundant achievements. In this method, after constructing the main body structure directly under the existing girder support, a so-called refilling beam (refilling girder support) is installed on the mountain retaining wall side of the main body side wall to support the existing girder. The existing girder support work is removed by replacing the axial force acting on the work.
For example, Patent Document 1 describes a form in which a refilling beam is installed in a skeleton in the middle of construction after removal of a girder support, and a refilling concrete is placed on the outside thereof ([0039]]. , FIG. 15 and the like.).
However, since the support work removal method involves work in a narrow space, it has various problems such as process delay, deterioration of safety, and increase of construction cost.
In order to solve these problems, Patent Document 2 describes an embodiment in which the number of refilling operations of the girder support is minimized by using an anchor in addition to the girder support as the support of the mountain retaining wall. Is disclosed.

JP-A-2017-96064 Japanese Unexamined Patent Publication No. 2017-96063

If the anchors can be arranged in a manner that does not interfere with the construction of the skeleton, it will be possible to reduce the number of replacements of the girder support, and the combined use of anchors is an excellent construction method from the viewpoint of securing a work space for replacement. However, in reality, the construction environment is such that the anchor itself cannot be applied due to restrictions such as the boundaries of private land, and there are many cases where it is unavoidable to adopt the inner beam replacement method.

In general, the inner beam replacement method consists of (1) construction of the side wall of the skeleton, (2) installation of the replacement beam, and (3) removal of the mountain retaining beam support. Since a separate scaffold is required for each procedure, the work of assembling and disassembling the scaffold increases, which is inefficient.
In addition, the girder support works are often placed in the same plane position on all stages, and the dismantling and removal of the existing girder support works and the erection work of the replacement beams are the work directly under the remaining existing girder support works. Therefore, the efficiency of the loading and unloading work from directly above is significantly reduced.

The present invention has been made in view of such circumstances, and makes it possible to efficiently perform work such as installation / removal of scaffolding for each work, removal of existing girder support, and erection of replacement beams. The subject is to provide a method for constructing a skeleton.

In order to solve the above-mentioned problems, the skeleton construction method of the present invention is a skeleton construction method for constructing a skeleton inside an excavation pit in which a plurality of girder supports are installed on a mountain retaining wall. A skeleton construction process in which a skeleton is sequentially constructed from the bottom of the pit, and (B): a replacement beam erection process in which a unit pedestal is placed inside the constructed skeleton and a replacement beam is erected while being fixed to the upper part of the unit pedestal. And (C): lining plate laying step of laying the lining plate using the replacement beam as a girder, and (D): removal of the girder support work to remove a part of the multi-stage girder support work. It is characterized in that the steps (A) to (D) are repeated a plurality of times, including the steps.
According to the skeleton construction method, the unit pedestal is also used as a scaffold for building the skeleton or a formwork support, a scaffold for heavy machinery for dismantling the girder support, etc. Can be significantly reduced.

The unit pedestal except for the lowermost stage of the step (B) may be installed on the lining plate already installed.
A strong steel stage with a lining plate laid on the upper part of each stage of a highly rigid unit pedestal can be laminated, and heavy machinery such as crawler cranes can be operated on the stage, which enables existing demolition beams. The dismantling work of the support work can be carried out more safely.

The refilling beam in the step (B) may be erected via the side wall of the skeleton.
By erection of the refilling beam via the side wall of the skeleton constructed along the inside of the mountain retaining wall with external loads such as earth pressure and water pressure acting on the mountain retaining wall, the flexural rigidity outside the side wall can be expected. The abdominal material can be omitted.

The unit mount in the step (B) may be grounded in advance on the ground.
Since it is unitized on the ground, dangerous aerial work in a narrow underground can be reduced, and if the unit is suspended from the ground by a lifting machine such as a crane, the installation efficiency can be improved.

The hydraulic equipment of the refilling beam in the step (B) may be arranged in a place not covered by the lining plate.
By arranging the hydraulic equipment of the refilling beam in a place not covered by the lining plate, it is possible to easily manage the axial force acting on the refilling beam.

The unit mount in the step (B) may be provided with a moving device capable of moving in the horizontal direction.
By adding a moving device with a moving function to the unit pedestal, it is possible to move directly under the existing girder support.

According to the method for constructing an underground structure of the present invention, the unit pedestal can be used as a scaffold for constructing a skeleton or a scaffold for heavy machinery for formwork support and dismantling of girder support, thereby providing a temporary scaffold in each work. The amount of assembly work can be significantly reduced.
In addition, if a strong steel stage with a lining plate laid on the upper part of each stage of the unit pedestal is provided, heavy machinery such as crawler cranes can be operated on the stage, which enables the existing girder support. The dismantling work can be carried out more safely.
In addition, by installing a refilling beam via the side wall of the skeleton to apply external loads such as earth pressure and water pressure acting on the mountain retaining wall, bending rigidity outside the surface of the side wall can be expected, so the abdominal raising material can be omitted. Furthermore, if the unit mount is unitized on the ground, dangerous aerial work in a narrow underground can be reduced, and if each unit is suspended from the ground by a lifting machine such as a crane, the installation efficiency can be improved.
In addition, by arranging the hydraulic jack of the refilling beam in a place not covered by the lining plate, it is possible to easily manage the axial force acting on the refilling beam, and a moving device having a moving function on the unit pedestal can be provided. By adding it, it will be possible to move directly under the existing girder support.

It is a cross-sectional view after excavation / Yamadome support work and construction of the skeleton bottom slab. It is sectional drawing at the time of installation of the 1st stage unit pedestal of this invention, and erection of a replacement beam. It is a detailed view of the unit pedestal and the refilling beam of this invention (the part A of FIG. 2). It is sectional drawing which completed the installation of the 1st stage unit pedestal of this invention, the erection of a replacement beam, and the laying of a lining plate. It is a detailed view at the time of laying the lining board using the 1st step refilling beam of this invention as a girder (cross section BB of FIG. 4). It is sectional drawing at the time of removal work of the existing girder support work on the 1st stage lining plate of this invention. It is sectional drawing at the time of installation of the 2nd stage unit pedestal of this invention, and erection of a replacement beam. It is sectional drawing at the time of completion of the skeleton construction using the unit pedestal, the refilling beam and the lining plate of this invention. It is sectional drawing at the time of removal work of the unit frame, the replacement beam and the lining plate of this invention. It is sectional drawing after completion of the removal work of the unit frame, the replacement beam and the lining plate of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a cross-sectional view after excavation / Yamadome support work and construction of a skeleton bottom slab.
After constructing the mountain retaining wall 1 on the ground G, excavating the inside of the mountain retaining wall 1 and erection of the girder support 2 in multiple stages, excavating to the floor mounting surface 3, and then placing the foundation concrete 31. Build the skeleton bottom plate 41. In the gap between the skeleton bottom slab 41 and the mountain retaining wall 1, the concrete to be placed when constructing the skeleton may be placed as it is, but in this embodiment, it is necessary to guide water leakage from the mountain retaining wall 1. Therefore, the concrete to be cast at the time of building the skeleton is not cast as it is, and the filler 32 (slurry fluidized soil) is filled after the completion of the skeleton construction. As a result, external forces such as earth pressure and water pressure transmitted from the mountain retaining wall 1, which will be described later, are reliably transmitted to the replacement beam 7 via the skeleton 4.
The mountain retaining wall 1 is constructed by the SMW method (soil mixing wall method). The SMW method is a multi-screw kneading auger machine (not shown) that drills a hole in the original ground, discharges cement slurry from the tip of the hole, and kneads it with the drilled ground to knead the SMW wall 12 (soil cement wall). ). In the present embodiment, by curing the SMW wall body 12 in a state where the core material 11 is embedded in each drilling hole, the SMW wall body 12 is integrated in a state where the circumference of the core material 11 is covered with the SMW wall body 12. A highly rigid mountain retaining wall 1 that also has water blocking properties is constructed.
The girder support 2 is composed of a bracket 2B, a raised 2W, and a girder 2S. A raised 2W made of H-shaped steel is placed on a bracket 2B made of L-shaped steel fixed by welding to the flange surface of the core material 11 exposed by drilling the SMW wall body 12 on the inner air side. Then, the girder 2S is connected so as to be angry and orthogonal to the 2W. Each member is mainly connected with bolts and nuts. As for the gap between the core material 11 and the raised 2W, an external force acting on the core material 11 is surely transmitted to the girder support 2 by installing a filling material (not shown) as needed.
Further, in FIG. 1, a temporary scaffold K for constructing the skeleton side wall 42 is installed. The temporary scaffold K uses a framework scaffold so that it can be easily assembled and disassembled.

FIG. 2 shows a cross-sectional view at the time of installing the first-stage unit pedestal and erection of the replacement beam.
The unit mounts 5, 5, 5 ... Assembled on the ground are sequentially thrown onto the skeleton bottom slab 41 by the crane CR. The inserted unit pedestal 5 is arranged at a predetermined position by lateral pulling movement. The joist 6 and the replacement beam 7 are sequentially installed and fixed on the unit pedestal 5 for which the arrangement is completed. The refilling beam 7 is composed of a long main material 71, an adjusting material 72 for length adjustment, and a hydraulic jack 73 for the purpose of loading a preload on the refilling beam 7 and managing axial force. ..

FIG. 3 shows a cross-sectional view of a unit pedestal and a replacement beam, which are details of part A in FIG.
The pillar portion of the unit pedestal 5 is configured by connecting a support member 52 on a base jack 51 and further connecting a large pulling member 53 on the support member 52. The unit pedestal 5 is formed by joining the plurality of pillars facing each other with the plurality of horizontal lumbers 54 and the slanted lumbers 55. In this embodiment, a so-called leased pipe support type formwork support material is applied.
The unit pedestal 5 is preliminarily assembled to a predetermined size on the ground, and the lengths of the base jack 51 and the large pulling material 53 are adjusted in advance in consideration of the planned installation height of the replacement beam 7, and then the skeleton bottom plate. It is thrown on 41.
The unit pedestal 5 mounted on the skeleton bottom plate 41 is laterally moved to a predetermined position. For horizontal pulling, it may be moved by placing it on a trolley or a seat with low frictional force.
Joist materials 6, 6, 6 ... Are placed on the joist 53 of a plurality of unit mounts 5 arranged at predetermined positions, and the joist 53 and the joist 6 are separated by a fixing jig (not shown). Fix it integrally. As the fixing jig, a vise type jig that is distributed for temporary fixing is desirable because it is easy to assemble and disassemble.
On the installed joist lumber 6, 6, 6 ..., the refilling beam 7 is placed so as to be orthogonal to the joist lumber 6, 6, 6 ... And fixed with a fixing jig in the same manner as described above. ..
In this embodiment, the joist 6 and the refilling beam 7 on which the axial force from the unit pedestal 5 acts are located between the upper and lower flanges of the H-shaped steel constituting the joist 6 and the refilling beam 7. A buckling prevention material 8 is installed for the purpose of preventing buckling.

FIG. 4 shows a cross-sectional view of the completion of the installation of the first-stage unit pedestal, the erection of the replacement beam, and the laying of the lining plate.
As described above, the refilling beam 7 is adjusted in length by using a plurality of adjusting materials 72, and is arranged so as to stretch the opposite skeleton side walls 42 (421) and 42 (421). In the present embodiment, since the force distribution muscle is arranged on the skeleton side wall 42, the abdominal raising material between the skeleton side wall 42 and the refilling beam 7 is unnecessary, but the shaft acting on the refilling beam 7 is not required. If the force is large and there is a concern about the influence of the supporting pressure on the side wall 4 of the skeleton, an abdominal upset may be used if necessary.
Further, a lining plate 9 using the refilling beams 7 and 7 as a girder is installed so as to straddle the refilling beams 7 and 7. The lining plate 9 is arranged so that the adjacent lining plates 9 and their side surfaces are in close contact with each other without a gap, and the side surfaces thereof are arranged along the central axis of the H-shaped steel constituting the replacement beam 7.
A hydraulic jack 73 is arranged at the end of the refilling beam 7. The lining plate 9 is not installed directly above the arranged hydraulic jack 73. This makes it possible to easily visually manage the axial force during preloading and operation. In this embodiment, since the upper part of the hydraulic jack 73 is an opening, a handrail material 10 for opening curing is installed as needed.

FIG. 5 shows a side view at the time of laying a lining board using the first-stage refilling beam as a girder, which is the details of the BB cross section of FIG.
If the refilling beams 7, 7, 7 ... Are arranged so as to match the dimensions of the lining plate 9, the lining plates 9, 9, 9 ... Can be spread without gaps, and the refilling beams 7, 7, 7 ... 7, 7 ... A high-rigidity steel stage can be constructed on the top. As a result, heavy machinery and the like can be worked on the lining plates 9, 9, 9, ..., Therefore, work efficiency such as dismantling of the girder support 2 and construction of the skeleton 4 can be improved.

FIG. 6 shows a cross-sectional view of the existing girder support during the removal work on the first-stage lining plate.
Since it can be performed while using heavy machinery on the lining plates 9, 9, 9 ..., the construction efficiency is significantly improved as described above.

FIG. 7 shows a cross-sectional view at the time of installing the second-stage unit pedestal and erection of the replacement beam. The refilling beam 7 is arranged so as to stretch the opposing skeleton side walls 42 (422) and 42 (422). The installation work of the unit frame 5, joist 6 and replacement beam 7 from the second stage onward is performed on a stable steel stage with no unevenness and the lining plates 9, 9, 9 ... in the previous stage. Therefore, the work can be performed with the same efficiency as the work on the first-stage skeleton bottom plate 41.

FIG. 8 shows a cross-sectional view at the time of completion of the skeleton construction using the unit pedestal, the replacement beam and the lining plate.
After the construction of the skeleton side wall 42 is completed, the skeleton including formwork installation, reinforcing bar arrangement, concrete placement and curing, etc. is taken from the unit mounts 5, 5, 5 ... The top plate 43 can be constructed.

FIG. 9 shows a cross-sectional view at the time of removing the unit pedestal, the refilling beam and the lining plate, and FIG. 10 shows a cross-sectional view after the removal work of the unit pedestal, the refilling beam and the lining plate is completed.
From the opening 431 provided in the skeleton top plate 43, the unit pedestal 5, 5, 5 ..., the lining plate 9, 9, 9 ..., the replacement beam 7, 7, 7 ... Temporary materials such as joist materials 6, 6, 6 ... etc. are sequentially carried out to the ground.
In particular, since the unit pedestal 5 can be carried out for each unit, it is superior to the conventional method in terms of safety and efficiency, unlike the detailed dismantling work in a narrow underground space.

According to the skeleton construction method of the present embodiment, the unit pedestal is also used as a scaffold for skeleton construction or a formwork support, and a scaffold for heavy machinery for dismantling a girder support, thereby assembling a temporary frame scaffold in each work. The amount can be significantly reduced, and if a strong steel stage with lining plates is installed above each stage of the unit frame, heavy machinery work such as crawler cranes will be possible on the stage. Therefore, the dismantling work of the existing girder support can be carried out more safely.
In addition, by installing a refilling beam via the side wall of the skeleton to apply external loads such as earth pressure and water pressure acting on the mountain retaining wall, bending rigidity outside the surface of the side wall can be expected, so the abdominal raising material can be omitted. Furthermore, if the unit mount is unitized on the ground, dangerous aerial work in a narrow underground can be reduced, and if each unit is suspended from the ground by a lifting machine such as a crane, the installation efficiency can be improved.
In addition, by arranging the hydraulic jack of the refilling beam in a place not covered by the lining plate, it is possible to easily manage the axial force acting on the refilling beam, and a moving device having a moving function on the unit pedestal can be provided. By adding it, it will be possible to move directly under the existing girder support.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be appropriately modified without departing from the spirit of the present invention.
For example, in addition to the unit pedestal, a joist material, a replacement beam, and a lining plate may be integrated into a unit and put into the ground.

G Ground K Temporary scaffolding CR Crane 1 Mountain retaining wall 2 Cutting beam support 3 Flooring surface 4 Frame 5 Unit pedestal 6 Joist 7 Refilling beam 8 Buckling prevention material 9 Backing plate 10 Handrail material

Claims (6)

In the skeleton construction method of constructing the skeleton inside the excavation pit where multiple steps of girder support are installed on the mountain retaining wall
(A): A skeleton construction step of sequentially constructing a skeleton from below the excavation pit, and
(B): A refilling beam erection process in which a unit pedestal is placed inside the constructed skeleton and a refilling beam is erected while being fixed to the upper part of the unit pedestal.
(C): A lining board laying process in which a lining board is laid using the replacement beam as a girder.
(D): A cutting beam support removing step of removing a part of the multi-stage cutting beam support, and a process of removing the cutting beam support.
Including
A method for constructing a skeleton, which comprises repeating the steps (A) to (D) a plurality of times. The skeleton construction method according to claim 1, wherein the unit pedestal except for the lowermost stage of the step (B) is installed on the lining plate already installed. The skeleton construction method according to claim 1 or 2, wherein the refilling beam in the step (B) is erected via a side wall of the skeleton. The skeleton construction method according to claim 1 to 3, wherein the unit pedestal in the step (B) is preliminarily assembled on the ground. The skeleton construction method according to claim 1 to 4, wherein the hydraulic equipment of the refilling beam in the step (B) is arranged at a position not covered by the lining plate. The skeleton construction method according to claim 1 to 5, wherein the unit mount in the step (B) is provided with a moving device capable of moving in the horizontal direction.

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