JP2009121114A - Construction bearing structure, method of constructing underground construction, and method of replacing bearing of foundation load - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a foundation bearing structure which enables to carry out construction work of an underground construction even immediately under a foundation of an aboveground construction. <P>SOLUTION: The construction bearing structure 100 is provided for carrying out the construction work of the underground construction 200, at a location under a footing 3 of a viaduct 1, and formed of: underground walls 30 with nodes, which are constructed at locations corresponding to both sides of the underground construction 200; and a mat slab 20 which extends between upper edges of the underground walls 30 with the nodes, constructed at the locations corresponding to both the sides of the underground construction 200, covers side surfaces and an upper surface of the footing 3, and forms a unitary body with the underground construction 200. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for constructing an underground structure below a foundation of a structure such as a viaduct, and a support structure for the underground structure.

Conventionally, when constructing a new underground structure directly under the foundation of a structure such as a viaduct, a support structure is constructed so as to support the footing that is the foundation of the viaduct, and below that Is being constructed. FIG. 7 is a diagram illustrating an example of a conventional support structure. As shown in the figure, conventionally, an underground wall 130 is constructed on the side portion of the underground structure 200 to be constructed, and the underground is installed below the footing 3 so as not to interfere with the pile 4 that supports the footing 3. The temporary support girder 120 is bridged between the walls 130, and the footing 3 is supported by replacing the load from the footing 3 from the pile 4 via the jack 140 by the temporary reception girder 120, and then the pile 4 is removed. The underground structure 200 was constructed (see, for example, Non-Patent Document 1). The jack 140 is bent in the temporary support beam 120 and the underground wall 130 so that the footing 3 does not sink when the lower part of the temporary support beam 120 is excavated to construct the underground structure 200. It is provided to absorb the sinking.
Nobuyoshi Nakamura, Tsutomu Kawamura “Underpinning Forms and Selection”, Monthly “Basic Engineering” June 2001 issue, Research Institute for Civil Engineering, June 2001, VOL.29, No.6, p.2-p .Five

  However, in the above temporary support structure, since the temporary support girder and the jack are provided below the footing, there is a problem that the construction work of the underground structure cannot be performed directly under the footing.

  The present invention has been made in view of the above problems, and its purpose is to eliminate the need for a jack and a temporary support girder provided below the footing, so that even under the foundation of the ground structure, It is to provide a support structure of a foundation that can perform a construction work of a structure.

  The structure support structure of the present invention is a structure support structure for constructing an underground structure under a pile foundation or a direct foundation, which is the foundation of the structure. It is constructed so that it is integrated with the footing of the pile foundation or the direct foundation between the underground wall or pile constructed on both sides of the position where it hits and the underground wall or pile constructed on the both sides. And a supported member.

In the structure support structure described above, the support member may be a footing of the pile foundation or a reinforced concrete member, a steel concrete member, or a steel reinforced concrete member constructed so as to cover the side and the upper side of the direct foundation. Furthermore, the support member may be constructed in a plate shape.
The underground wall or pile may be a knotted underground wall or a knotted pile.

  The underground structure construction method of the present invention is a method of constructing an underground structure below a pile foundation or a direct foundation, which is the foundation of the structure, on both sides of the position corresponding to the underground structure. Constructing underground walls or piles, and constructing support members so as to be integrated with the footings of the pile foundation or the direct foundation between the underground walls or piles constructed on both sides, The underground structure is constructed in a space formed by excavating the footing of the pile foundation or the lower side of the direct foundation and excavating the pile foundation.

  The foundation load replacement method of the present invention is a pile foundation that is a foundation of a structure or a replacement method that transfers a load acting on the foundation directly from the structure to another foundation structure, the pile foundation The support member is constructed integrally with the footing or the direct foundation, and the other foundation structure is constructed, and the load acting on the support member from the structure is transmitted to the other foundation structure. .

  According to the present invention, a load is received by a plate-like concrete member that is constructed integrally with the foundation so as to cover the side and upper side of the foundation of the structure, and this load is transmitted to the ground by an underground wall or a pile. Even if provisional girders and jacks are not provided under the footing or directly under the foundation, the construction work of the underground structure can be performed directly under the foundation.

Hereinafter, an embodiment in which the structure support structure of the present invention is applied to a case where an underground structure is constructed below a viaduct provided with a footing will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing a support structure 100 of the present embodiment. The support structure 100 of the present embodiment is a structure for supporting the footing 3 from below when the underground structure 200 such as a subway is constructed below the existing footing 3 of the viaduct 1. As shown in FIG. 1, the support structure 100 includes a knotted underground wall 30 constructed at a position corresponding to both sides of the underground structure 200 to be constructed, and a pressure plate 20 constructed integrally with the footing 3. .

  The knotted underground wall 30 is an underground wall in which a protruding portion 31 protruding outward is formed on the surface of the underground wall main body. When a pushing load directed vertically downward acts on the knotted underground wall 30, it can be resisted by the supporting pressure acting on the protruding portion 31 from the ground in addition to the surface frictional force of the underground wall body. Thus, the knotted underground wall 30 is provided with a resistance force against the pushing load as compared with a normal underground wall.

  The pressure plate 20 is a reinforced concrete, steel concrete, or steel reinforced concrete plate-like member constructed so as to cover the upper surface and side surfaces of the footing 3, and is constructed over the upper portions of the nodal underground walls 30 on both sides. ing. Anchor bars 21 are provided on the surface of the footing 3, and the pressure plate 20 is constructed so as to embed the anchor bars 21, and the footing 3 and the pressure plate 20 function as an integral structure.

  Hereinafter, a method for constructing the above-described support structure 100 and constructing the underground structure 200 using the constructed support structure 100 will be described. 2 to 6 are vertical sectional views for explaining a method for constructing the underground structure 200 using the constructed support structure 100 by constructing the support structure 100.

  First, as shown in FIG. 2, the underground wall 30 with a node is constructed at the portions corresponding to both sides of the underground structure 200 to be constructed. That is, the excavation device excavates the position corresponding to the grounded subterranean wall 30 in the vertical direction and excavates the portion corresponding to the projecting portion 31 to form a drilling hole that matches the shape of the subterranean underground wall 30. Then, a reinforcing steel cage is built as a core material in the excavation hole, and concrete is placed. At this time, as shown in FIG. 2, the knotted underground wall 30 is constructed so that the upper end is at a height corresponding to the lower surface of the pressure plate 20, and a reinforcing bar for connecting to the pressure plate 20 is protruded from the upper part. Keep it.

  Next, as shown in FIG. 3, the ground corresponding to the pressure plate 20 is excavated so that the upper surface and side surfaces of the footing 3 are exposed. Then, anchors 21 are placed on the upper surface and side surfaces of the footing 3.

  Next, as shown in FIG. 4, a pressure plate 20 is constructed. That is, first, when the pressure plate 20 is made of reinforced concrete, the reinforcing bar is arranged. When the pressure plate 20 is made of steel-concrete, the steel is built, and the pressure plate 20 is made of steel-reinforced concrete. When doing so, the construction work of the steel frame and the reinforcement work of the reinforcement are performed. And the concrete which comprises the pressure-resistant board 20 is laid. When the cast concrete is hardened, the footing 3 and the pressure plate 20 are united by the anchor bars 21. The support structure 100 is constructed by the above steps.

  Next, as shown in FIG. 5, using the knotted underground wall 30 as a retaining wall, the cutting plate 20 Drill the ground below. At this time, by excavating the ground below the footing 3, the reaction force received by the footing 3 from the ground and the peripheral frictional force acting on the peripheral surface of the pile 4 do not act, and the pressure plate from the viaduct 1 The load transmitted to 20 is transmitted to the knotted underground wall 30 as a pushing load. On the other hand, as described above, the knotted underground wall 30 has improved resistance to the indentation load as compared with the normal underground wall, so that the footing 3 and the pressure plate 20 are supported without sinking. Can do. Thus, since the load of the viaduct 1 can be supported by the support structure 100, when the pile 4 under the footing 3 interferes with the underground structure to be constructed, the pile 4 may be cut off.

Next, as shown in FIG. 6, by performing the bar arrangement work, the formwork installation work, and the concrete placement work in the space formed by excavating between the ground walls 30 with the nodes on both sides, The middle structure 200 is constructed.
In addition, after construction of the underground structure 200, the viaduct 1 may be supported by the support structure 100 described above, or a new foundation structure may be constructed and the viaduct 1 may be supported by this foundation structure.

  As described above, according to the support structure 200 of the present embodiment, the load of the viaduct 1 is received by the pressure plate 20 constructed so as to cover the side surface and the upper surface of the footing 3, and the load received by the pressure plate 20 is received. Since it is configured to transmit to the underground wall 30 with a node, there is no support structure such as a temporary girder or a jack directly under the footing 3, and the construction work of the underground structure 200 can be performed directly under the footing 3. it can. For this reason, while being able to improve the workability at the time of constructing the underground structure 200, for example, it is possible to design the upper surface of the underground structure 200 to be located directly below the footing 3. The degree of freedom is improved.

  Further, since the pressure plate 20 is constructed so as to cover the side surface and the upper surface of the footing 3, it can be constructed on the ground, so that the workability can be improved. Further, by constructing the pressure plate 20 so as to cover the upper side and the side of the footing 3 as described above, even if the pressure plate 20 is thickened, it does not become an obstacle when the underground structure 200 is constructed. 20 can be thickened as necessary, and the pressure-resistant plate 20 can have sufficient bending strength.

  Conventionally, as shown in FIG. 7, a provisional girder 120 that supports the footing 3 is constructed below the footing 3. As described above, the members supporting the footing 3 are formed in the shape of a girder because, when the support structure 300 is constructed, if all the ground below the footing 3 is excavated, there is a risk of subsidence. This is because only a part of the lower ground can be excavated. On the other hand, according to this embodiment, since the pressure plate 20 is shaped to cover the upper side and the side of the footing 3, the plate-like pressure plate 20 is not excavated below the footing 3 as described above. Can be built. Thus, since the pressure plate 20 that receives the load of the footing 3 can be formed into a plate shape, the bending strength of the pressure plate 20 can be improved.

  Further, in the conventional support structure 300 shown in FIG. 7, when the ground between the underground walls 130 is excavated below the provisional girder 120, the peripheral friction force acting on the pile 4 disappears and the load of the viaduct 1 is It will be transmitted to the underground wall 130 via the provisional girder 120. However, when the load of the viaduct 1 acts on the temporary support girder 120 in the state where the ground between the underground walls 130 is excavated, the central portion of the temporary support beam 120 bends downward, and accordingly, the underground wall 130. Will be deformed inward. As a result, the peripheral frictional force between the underground wall 130 and the outer ground is lowered, and there is a possibility that the viaduct 1 and the entire support structure 300 may sink without obtaining sufficient support force. On the other hand, in this embodiment, the bending which arises in the pressure plate 20 can be suppressed by giving the pressure plate 20 sufficient bending strength as described above. Further, since the pressure plate 20 is supported from below by the knotted wall 30, even if the load of the viaduct 1 acts on the pressure plate 20 downward, the knotted wall 30 is prevented from being deformed inward. Thereby, it can suppress that the peripheral surface frictional force which the wall 30 with a node receives from a ground falls. Furthermore, since the knurled wall 30 is provided with the protrusion 31, the resistance force against the indentation load is improved, so that the viaduct 1 can be more effectively prevented from sinking.

  Further, conventionally, the jack 140 is provided between the footing 3 of the viaduct 1 and the temporary support 120 supporting the load so that the viaduct 1 does not sink when the temporary support 130 is bent as described above. By interposing and extending this jack 140, this bending was absorbed. On the other hand, in this embodiment, since the deformation | transformation of the pressure | voltage resistant board 20 can be suppressed as mentioned above, the jack for absorbing a bending becomes unnecessary. Thereby, the space for providing a jack becomes unnecessary, and work such as installation of a jack can be omitted, and workability can be improved.

  In the above embodiment, the ground reaction force is obtained by the knotted underground wall 30 and the pressure plate 20 is supported. However, the present invention is not limited to this, and the knotted pile is changed to the knotted underground wall 30. As long as a sufficient ground reaction force can be obtained, ordinary underground walls and piles may be used.

  In the present embodiment, the case where the underground structure is constructed below the viaduct provided with the footing provided with the pile below is described as an example. However, the present invention is not limited thereto. The present invention can also be applied to a case where an underground structure is constructed below a structure having a foundation structure such as a foundation.

It is sectional drawing which shows the support structure of this embodiment. It is a figure for demonstrating the method of constructing | supporting a structure, and shows the state which constructed | assembled the underground wall with a node in the part which hits the both sides of an underground structure. It is a figure for demonstrating the method of constructing | supporting a support structure, and shows the state which excavated the part which corresponds to the pressure plate of a ground, and laid the anchor. It is a figure for demonstrating the method to construct | support a support structure, and shows the state which laid concrete which comprises a pressure | voltage resistant board. It is a figure for demonstrating the method to construct | assemble an underground structure, and is a figure which shows the state which is excavating the lower ground. It is a figure showing the state where construction of the underground structure was completed. It is sectional drawing which shows the conventional support structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Viaduct 2 Pier 3 Footing 4 Pile 20 Pressure-proof board 21 Anchor 30 Underground wall 31 with a node Projection part 100 Support structure 200 Underground structure

Claims (6)

A structure supporting structure for constructing an underground structure below a pile foundation or direct foundation, which is the foundation of the structure,
Underground walls or piles constructed on both sides of the position hitting the underground structure,
A support member constructed so as to be integrated with the footing of the pile foundation or directly with the direct foundation across the underground wall or the upper part of the pile constructed on both sides. Support structure.   2. The structure according to claim 1, wherein the support member is a reinforced concrete member, a steel concrete member, or a steel reinforced concrete member constructed so as to cover a footing of the pile foundation or a side and an upper side of the direct foundation. Support structure.   3. The structure support structure according to claim 1 or 2, wherein the support member is constructed in a plate shape.   The structure support structure according to any one of claims 1 to 3, wherein the underground wall or pile is a noded underground wall or a noded pile. A method of constructing an underground structure below a pile foundation or direct foundation, which is the foundation of the structure,
Build underground walls or piles on both sides of the position hitting the underground structure,
A support member is constructed so as to be integrated with the footing of the pile foundation or the direct foundation across the underground wall or the upper part of the pile constructed on both sides,
Excavating the footing of the pile foundation or below the direct foundation;
A construction method for an underground structure, wherein the underground structure is constructed in a space formed by the excavation. It is a replacement method for transferring the load acting on the pile foundation which is the foundation of the structure or the direct foundation to another foundation structure,
While constructing a support member integrally with the footing of the pile foundation or the direct foundation, constructing the other foundation structure, and transmitting the load acting on the support member from the structure to the other foundation structure A characteristic foundation load replacement method.