JP2009013659A - Method of reinforcing underground structure with inner void - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve aseismatic performance by reinforcing an underground structure comparatively large in the extent of having an inner void, from the inside of the structure and to allow the existing structure to effectively function again at a low cost without being newly constructed and furthermore without affecting the peripheral ground of the structure. <P>SOLUTION: Bore hole parts are bored in a top slab of the underground structure, and a cement-based material is put into the inner void parts of the underground structure from the bore hole parts. The cement-based material is put in pits in the structure in every bore hole part of the top slab, and the cement-based material is solidified to integrate reinforcing bodies formed of the cement-based material, with the underground structure, or to increase the thickness of internal sidewalls. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an improvement in the proof stress of an existing underground structure in the construction field, and relates to a method for reinforcing an underground structure that is reinforced from the inside of the underground structure.

  When designing a structure, the basis for the seismic design is the ground motion strength expected during the service period of the structure. The review of design standards for construction structures has been considered, and the seismic standards have been gradually improved.

  In other words, there are many structures that have been built based on the old design that do not satisfy the current seismic performance, and there is an urgent need for reinforcement work to improve the proof strength to the latest design standards.

  Here, various reinforcement methods have been proposed for constructing high-strength structures on the upper part of the ground surface, that is, on the structure part that protrudes from the ground part. Reinforcement work has been done in

  However, it is difficult to directly reinforce the structure part buried in the underground part, so take measures to reduce the influence of external force on the underground structure indirectly by solidifying and improving the surrounding ground. There are many examples.

  In particular, for ground structures with large aspect ratios such as piles and pillars, ground improvement techniques such as those described above are frequently used, but their service forms are relatively large, such as caisson. When it is a foundation or a container structure that requires a large space such as a basement, it is necessary to create a large-scale improvement body of the ground. It is not an ideal method.

  Conventionally, some of these large underground structures have seismic performance that satisfies the design standards even after the standards of the seismic design guidelines have been changed. As the earthquake resistance standards improved at once, there is an increasing number of cases that require reinforcement work even for large underground structures.

JP 2001-214465 A JP 2003-055998 A

  Therefore, the present invention has been devised in view of the above-mentioned problems, and by reinforcing a relatively large underground structure having an inner space from the inside of the structure, the seismic performance is improved. The problem is solved by effectively re-functioning an existing structure without incurring a new construction and without affecting the surrounding ground of the structure.

  In order to achieve the above object and to solve the problems, the present invention is configured as follows.

  According to the first aspect of the present invention, there is provided a method for reinforcing an underground structure having an inner space, in which a top plate of the underground structure is drilled at a plurality of positions by a drilling machine, and a cement-based material is formed from the drilled portion in the inner space of the underground structure. In addition, the cement-based material is cast-filled in all the perforated portions of the top plate, and the cement-based material is solidified to integrate the reinforcing body made of the cement-based material with the underground structure. The middle structure is reinforced from the inside.

  According to the second aspect of the present invention, a method for reinforcing an underground structure having an inner space includes drilling a top plate of the underground structure at a plurality of locations with a drilling machine, and reducing the cement-based structure from the drilled portion to the inner space of the underground structure. A certain amount of high-strength material is cast to a height that does not require reinforcement, the cement-based low-strength material is solidified, and the height required to reinforce the upper space above the solidified cement-based low-strength material from the perforated part to the cement-based material And filling the cementitious material in all of the perforated parts of the top plate, solidifying the cementitious material and integrating the cemented material with the underground structure It is characterized by reinforcing objects from the inside.

  According to the third aspect of the present invention, there is provided a method for reinforcing an underground structure having an inner space, in which a certain distance is maintained from the interior of the underground structure to the inner surface of the wall of the underground structure, and concrete molding is performed at a location requiring reinforcement. Install the formwork, place and fill the cement material into the space formed by the underground structure wall and the concrete molding formwork, solidify the cement material and reinforce the cement material The underground structure is reinforced from the inside by increasing the thickness of the wall of the underground structure.

  According to claim 4 of the present invention, there is provided a method for reinforcing an underground structure having an inner space. In the invention according to claim 3, a certain distance is provided from the interior of the underground structure to the inner surface of the underground structure wall. A reinforcing steel plate is installed, and a reinforcing body made of the reinforcing steel plate and a cement-based material is integrated with the underground structure to increase the thickness of the underground structure wall.

  In the invention according to any one of claims 1 to 4, the method for reinforcing an underground structure having an inner sky according to claim 5 of the present invention is characterized in that the cementitious material is made of high-strength fiber concrete.

  According to claim 6 of the present invention, there is provided a method for reinforcing an underground structure having an inner sky. In the invention according to any one of claims 1 to 5, Reinforcing bars or PC tendons are arranged along the side surface, or a fiber sheet for concrete reinforcement is attached.

  According to the present invention, a method for seismic reinforcement of a structure having an internal space such as a large underground structure can be constructed economically without requiring ground improvement, the construction period is short, and a new construction is separately provided. It is possible to reinforce from the inside of an existing structure without constructing the structure, and it is possible to improve the strength of the structure without any influence on the surrounding ground outside the structure. Is.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings, taking as an example a case of reinforcing an underground structure built in the past as a bridge foundation.

  First, FIG. 1 is a longitudinal section of an underground structure to be reinforced in the embodiment of the present invention. As shown in FIG. 1, the underground structure 1a designed and built as the foundation structure of the pier 1g is lower than the original ground surface 2a and its scale is relatively large. The internal structure generally includes a plurality of intermediate walls 1b formed by the partition wall 1c together with the top plate 1d, the bottom plate 1e, and the side wall 1f. Further, when the underground structure 1a is lower than the groundwater level 2c. In the middle tank 1b, the inside water 2d is poured to the water level corresponding to the groundwater level 2c.

  FIG. 2 shows each step of a preparation stage for building a reinforcing body on the underground structure 1a. The first step in this preparation stage is to excavate the original ground surface 2a with an excavator or the like (not shown) to form the excavated ground surface 2b and expose the upper surface of the top plate 1d of the underground structure 1a.

  Next, the top plate 1d is perforated by the perforating machine 3a to perforate the perforated portion 3b, thereby providing a communication path to the intermediate collar 1b. At this time, in the underground structure 1a in which a plurality of center rods 1b are configured, the necessary number of perforations 3b are drilled according to the size and the number of components of the center rod 1b. Thereafter, access between the intermediate rod 1b of the underground structure 1a and the outside (the above-ground part) is performed by the drilled communication path. It should be noted that the opening size of the perforated part 3b may be minimized to the extent that the operator or necessary material can be taken in and out without affecting the structural yield strength.

  Next, when the underground structure 1a is lower than the groundwater level 2c, the filling water 2d poured into the middle tank 1b is drained by a drain pump or the like, and the underground structure constituting the middle wall 1b In accordance with the surface states of the inner wall surface of 1a, that is, the top plate 1d, the bottom plate 1e, the intermediate partition wall 1c, and the side wall 1f, the inside of the center rod 1b is washed with a water jet or the like (not shown). Furthermore, preprocessing such as roughening is performed as necessary for the subsequent steps (not shown).

  Next, the low-strength mortar 5a transported by the agitator truck 4 is cast from the perforated portion 3b directly into the intermediate rod 1b or by a concrete pump or the like to be solidified. Here, the part where the underground structure 1a according to the old design needs reinforcement, that is, the part that does not reach the required strength of the current design is the upper part of the cross section of the underground structure 1a (underground structure 1a). Therefore, reinforcement in the lower part of the structure (similarly, about one third of the lower side) is often not required. Therefore, the low-strength mortar as the cement-based low-strength material to be placed here is not a structural member of the reinforcing body described below, but a temporary work for constructing the reinforcing body in the underground structure 1a. Of course, fluidized soil or the like may be used because the floor is created and functions as a construction base surface, and it is also possible to simply lay sand or the like.

  FIG. 3 shows a construction state at the main stage of building a reinforcing body on the underground structure 1a. The ordinary concrete 5b transported by the agitator truck 4 is directly transferred from the perforated portion 3b to the middle trough 1b and the perforated portion 3b. Or, by placing and filling with a concrete pump or the like and solidifying it, the normal concrete 5b and the underground structure 1a are integrated with each other after a reinforcing body is built on the intermediate rod 1b of the underground structure 1a. Here, in the drawing, a reinforcing body is constructed for all the intermediate rods 1b, but of course, a perforated portion 3b is formed in the intermediate rod 1b necessary for reinforcement, and ordinary concrete 5b is cast and filled. do it. In addition, the underground structure 1a according to the old design often has a problem of insufficient vertical bar arrangement, and high strength fiber concrete 5b is used instead of ordinary concrete 5b in order to supplement this reinforcing bar strength. It is also possible to do. In this example, there is a case where a series of operations can be performed without requiring an operator to enter the inside of the middle rod 1b.

  Finally, the excavation ground surface 2b is restored to the state of the original ground surface 2a and the reinforcement is completed (illustration is omitted).

  In addition, as shown in FIG. 4, as a reinforcing pattern different from the above, after the concrete molding form 6 is installed over the place necessary for reinforcing the underground structure 1a, the ordinary concrete 5b and the high-strength fiber are similarly used. The concrete 5b is built directly into the center rod 1b and the perforated portion 3b partitioned by the concrete mold 6 or by filling with a concrete pump or the like to solidify, thereby constructing a reinforcing body for the underground structure 1a. The side wall 1f is increased in thickness by integrating with the side wall 1f of the object 1a.

  In this case, depending on the structural scale of the reinforcing body, it is possible to arrange reinforcing bars 7 and PC tendons 7 as needed, and to stick a concrete reinforcing fiber sheet to the side wall 1f, etc. It is also possible to use a reinforced steel plate 6 instead of the forming mold 6. However, since the input dimensions of the material are limited to some extent due to the size of the opening dimension of the perforated portion 3b described above, for example, the concrete mold 6 and the reinforcing steel plate 6 are processed into a strip shape in advance, and then inserted into the intermediate rod 1b. It will be assembled when installing in. Depending on the size of the opening of the perforated portion 3b described above, it can be used as an entrance for an operator as appropriate, or an entrance for connecting to the inside of the intermediate collar 1b is provided in the top plate 1d to assemble a reinforcing bar or PC tension material. Assemble by workers.

  When the side wall 1f is reinforced by increasing the thickness, the top plate 1d is naturally used for a portion that does not require reinforcement, such as a center collar 1b that does not have the side wall 1f (for example, the center center shown in FIG. 4). It is not necessary to drill the perforated portion 3b, and it is not necessary to drain the filling water 2d poured into the intermediate rod 1b.

  Further, the perforated portion 3b drilled as a communication path between the ground and the center rod 1b can be provided on the side wall 1f of the underground structure 1a. Will increase. However, such as when the underground structure 1a supports the pier 1g according to this example as a foundation, the construction plane of the top slab 1d is not widely available, and the degree of freedom of construction is restricted. Then, the means for installing the connecting path on the side wall 1f is effective. Further, the number of the perforated portions 3b formed in the top plate 1d can be reduced by perforating the middle partition wall 1c that partitions the middle collar 1b from the other middle collar 1b.

  Finally, as shown in FIG. 5, the filling water 2d is poured to the level of the groundwater level 2c to the intermediate anchor 1b with the reinforcement body, and the excavation ground surface 2b is restored to the state of the original ground surface 2a to complete the reinforcement. It becomes. In addition, when the reinforced steel plate 6 is installed, the work of demolding the concrete mold 6 is naturally omitted.

  In addition, when the underground structure 1a is completely lower than the groundwater level 2c (for example, below the river surface), the present invention is carried out after a temporary cut-off is performed in a form surrounding the underground structure 1a in advance. It is within the scope of the present invention to appropriately change the design of the configuration shown in the embodiment here.

It is sectional drawing of the underground structure used as the reinforcement object of embodiment of this invention. It is sectional drawing of an underground structure which shows the preparatory stage (The process of excavating an original ground, the process of drilling a top plate, and the process of placing low-strength mortar) which builds the reinforcement body of embodiment of this invention. It is sectional drawing of an underground structure which shows the process of constructing the reinforcement body which consists of concrete of embodiment of this invention. It is sectional drawing of an underground structure which shows the process of thickening a structure side wall from the inside with the reinforcement body which consists of concrete or reinforced concrete of embodiment of this invention. It is sectional drawing of the underground structure which shows the final state which thickens a structure side wall from the inside with the reinforcement body which consists of concrete of embodiment of this invention, concrete, a reinforcement steel plate, or reinforced concrete, and a reinforcement steel plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a Underground structure 1b Middle anchor 1c Middle partition wall 1d Top plate 1e Bottom base 1f Side wall 1g Bridge pier 2a Original ground surface 2b Excavation ground surface 2c Ground water level 2d Filled water 3a Drilling machine 3b Drilling part 4 Agitator truck 5a Cement system low strength Material (low strength mortar)
5b Cement-based material (ordinary concrete or high-strength fiber concrete)
6 Concrete mold or reinforcement steel plate 7 Reinforcing bar or PC tension material

Claims (6)

In the reinforcement of underground structures with inner space,
Drilling the top plate of the underground structure with a drilling machine at multiple locations,
Cement-based material is cast and filled from the perforated part into the inner space of the underground structure,
In addition, the cement-based material is cast and filled in all the perforated portions of the top plate
A method for reinforcing an underground structure having an inner space, wherein the underground structure is reinforced from the inside by solidifying the cement material and integrating a reinforcing body made of the cement material with the underground structure. In the reinforcement of underground structures with inner space,
Drilling the top plate of the underground structure with a drilling machine at multiple locations,
A certain amount of cement-based low-strength material is placed in the inner space of the underground structure from the perforated part to a height that does not require reinforcement,
Solidify cement-based low-strength material,
Furthermore, the cement-based material is cast and filled from the perforated part at a height that requires reinforcement of the upper space above the solidified cement-based low-strength material,
And filling the cementitious material in all the perforated part of the top plate,
A method for reinforcing an underground structure having an inner space, wherein the underground structure is reinforced from the inside by solidifying the cement material and integrating a reinforcing body made of the cement material with the underground structure. In the reinforcement of underground structures with inner space,
Maintain a certain distance from the inside of the underground structure to the inner surface of the underground structure wall, and install a concrete mold in a place that requires reinforcement.
Cement material is placed and filled in the space formed by the underground structure wall and the concrete mold,
An interior space characterized by reinforcing the underground structure from the inside by solidifying the cement-based material and integrating the reinforcing body made of cement-based material with the underground structure to increase the thickness of the underground structure wall A method for reinforcing underground structures. In the reinforcement of underground structures with inner space,
A certain distance from the inside of the underground structure to the inner surface of the wall of the underground structure is installed, and the reinforcing steel plate is installed.
4. The method for reinforcing an underground structure having an interior space according to claim 3, wherein a reinforcing body made of a reinforcing steel plate and a cement-based material is integrated with the underground structure to increase the thickness of the underground structure wall. . In the reinforcement of underground structures with inner space,
The method for reinforcing an underground structure having an inner space according to claim 1, wherein the cement-based material is high-strength fiber concrete. In the reinforcement of underground structures with inner space,
The reinforcing bar or PC tension material is arranged along the inner surface of the underground structure wall from the inside of the underground structure, or a fiber sheet for concrete reinforcement is attached. 5. A method for reinforcing an underground structure having an inner space according to 5.

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