JP2004092053A - Construction method for composite underground wall - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an underground construction method which is more rational than a conventional inverted construction method. <P>SOLUTION: When a reinforced concrete (RC) wall 5 is integrally provided inside an earth retaining wall 1 so that a composite underground wall 7 can be constructed, after the construction of the wall 1, ground inside the wall 1 is excavated in a stepwise manner, and at the stage of the excavation of a certain step, the RC wall 5 is provided inside the wall 1 which is exposed on the above step, so that the wall 7 can be constructed. After that, the excavation of the next step is performed. In the construction of the wall 7 on each step, the strength of integration of a core material 2 for the wall 1 with the RC wall 5 is set depending on the distribution of stress which is expected to occur in each part of the wall 7. The strength of the integration of the core material 2 with the RC wall 5 is set by adjusting a pitch of a stud 8 serving as a shear key which is provided in the core material 2. The excavation of the next step is performed after concrete is placed more thickly than a necessary thikness for cover concrete up to an excavated bottom surface on a certain step in the lower part of an outer peripheral beam 3 which is integrally provided in the RC wall 5 on the above step. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of constructing an underground skeleton of a building, and more particularly to a method of constructing a composite underground wall in which a retaining wall and a reinforced concrete wall are integrated by a reverse strike method.
[0002]
[Prior art]
As a construction method for constructing an underground skeleton of a building, a reverse striking method of gradually excavating the ground from the ground surface and constructing the underground skeleton downward has been widely adopted.
[0003]
8 to 12 show an outline of a conventional general reverse hitting method. First, as shown in FIG. 8, a temporary retaining wall 1, for example, a soil mixing wall (SMW) having an H-section steel 2 as a core material is provided in the ground. Next, as shown in FIG. 9, the ground surface inside the retaining wall 1 is excavated, and the outer beam 3 and the slab 4 on the first floor are constructed. After excavating to a level slightly deeper than B1FL as shown in FIG. 10 while supporting the retaining wall 1 by making the outer peripheral beam 3 and the slab 4 function as bulging and cutting beams, the outer periphery of the first basement The beam 3 and the slab 4 are constructed. Similarly, after excavating to a slightly deeper level than B2FL as shown in FIG. 11, the outer beam 3 and slab 4 on the second basement floor are constructed, and as shown in FIG. A reinforced concrete wall (RC wall) 5 as a basement wall is sequentially constructed from the first basement floor to complete the skeleton and the foundation of the basement floor. Generally, it is often the step of constructing the underground outer wall two layers later than the excavation floor.
[0004]
[Problems to be solved by the invention]
In the above-mentioned conventional reverse striking method, when deep excavation is performed or when the height of the basement floor is large, as shown in FIG. Since a moment is generated, it is necessary to ensure the required thickness of the retaining wall 1 and the cross section of the core material 2 large, and also, as shown in FIG. May need to be added as appropriate. However, when there is not enough room on the site, the thickness of the retaining wall 1 may not be sufficiently ensured. In addition to the permanent outer beams 3 and the slabs 4, the temporary oblique beams 6 and the intermediate cut beams are provided. Is complicated, and it is not preferable in terms of construction period and cost.
[0005]
Also, since the conventional retaining wall 1 is provided only as a temporary construction, it should be removed after the underground skeleton is completed. However, it is difficult to remove the retaining wall 1 such as SMW after the completion of the building. For this reason, they often remain without being removed even after construction is completed. In recent years, it is considered that construction waste is left without being disposed of, which is considered to be environmentally unfavorable.
[0006]
In view of the above circumstances, an object of the present invention is to provide an effective underground construction method which is based on the reverse construction method and which is more rational and more excellent in workability than the conventional reverse construction method.
[0007]
[Means for Solving the Problems]
The invention according to claim 1 is a method for constructing a composite underground wall by integrally providing a reinforced concrete wall inside a retaining wall, and after constructing the retaining wall, excavating the ground inside the retaining wall in a stepwise manner. At the stage when a certain step was excavated, a reinforced concrete wall was provided inside the retaining wall exposed to the step and a composite underground wall of the step was constructed, and then the next step was excavated. Features.
[0008]
According to the invention of claim 2, in the invention of claim 1, when constructing the composite underground wall of each step, the core material of the retaining wall is provided according to the stress distribution expected to occur in each part of the composite underground wall. It is characterized by setting the integrated strength with the reinforced concrete wall.
[0009]
According to a third aspect of the present invention, in the second aspect of the present invention, the setting of the integral strength of the core material of the retaining wall and the reinforced concrete wall is performed by adjusting the pitch of a stud as a shear key provided on the core material. I do.
[0010]
According to a fourth aspect of the present invention, in the invention of the first, second, or third aspect, after the lower part of the outer peripheral beam provided integrally with the reinforced concrete wall of a certain step is additionally struck to the excavation bottom of the step, the next step is excavated. It is characterized by the following.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
1 to 7 show an embodiment of the present invention. In the present embodiment, similarly to the above-mentioned conventional method, the inner ground of the retaining wall 1 made of SMW is excavated in a stepwise manner, and the underground skeleton is constructed by the reverse driving method. Is not simply provided as a temporary structure, and the RC wall 5 is not merely provided inside the composite basement wall, but the composite basement wall 7 in which the retaining wall 1 and the RC wall 5 are structurally integrated as necessary. And the composite basement wall 7 functions as a permanent basement wall, so that the retaining wall 1 is used as it is as a part of the main basement wall. The integrated strength of the retaining wall 1 and the RC wall 5 in each portion of the composite underground wall 7 is appropriately set according to the stress distribution in each portion of the composite underground wall 7.
[0012]
That is, in general, the deeper the underground wall is, the deeper it is subjected to a greater soil pressure, so that a greater stress is generated in the deeper portion. Therefore, in this embodiment, the stress distribution that will occur after the composite underground wall 7 is completed is assumed in advance, and On the basis of this, the integral strength of the retaining wall 1 and the RC wall 5 is set to be greater in a portion where the stress is larger, and the integral strength is set to be smaller in the portion where the stress is smaller, or it is intentionally overlapped. The rigidity of each part of the composite basement wall 7 is optimally set so as to match the stress state of each part by preventing the unification. The setting of such integral strength is performed by adjusting the presence or absence of the stud 8 as a shear key and the pitch thereof, and at the same time, appropriately setting the wall thickness of the RC wall 5.
[0013]
Specifically, as shown in FIG. 7, in the portion of the first basement floor, the composite basement wall 7 is not subjected to a very large soil water pressure, and therefore no significant stress is generated, so that the strength of the retaining wall 1 is expected here. It is sufficient to provide a normal RC wall 5 without necessity, and therefore, in this case, it is not necessary to integrate the retaining wall 1 and the RC wall 5 with a shear key or the like. And On the other hand, sufficient strength is required at depths below the third floor below the basement, so that the RC wall 5 is set thicker than the upper part and the strength of the retaining wall 1 is permanently installed. A large number of studs 8 are densely provided on the core material 2 of the retaining wall 1 so as to be effectively used as a part of the underground wall of the retaining wall 1. Is a completely synthetic wall that is firmly integrated. Further, in the part of the second basement floor, the stress is about the middle between the first basement floor and the third basement floor or lower, so the wall thickness of the RC wall 5 is set to about the middle accordingly, and the stud 8 is used to secure the mountain retaining wall. Although the pitch of the stud 8 is made larger than the pitch at the depth of the third basement floor or lower, the incomplete composite wall having a reduced integration strength is used, although the integration of the RC wall 1 with the RC wall 5 and the outer peripheral beam 3 is intended.
[0014]
Thus, by setting the integrated strength of the core material 2 of the retaining wall 1, the RC wall 5, and the outer peripheral beam 3 in accordance with the stress distribution expected to occur in each part of the composite underground wall 7, The wall thickness and strength of each part of the basement wall 7 can be optimally set, and waste that would be unnecessarily large can be eliminated. In addition, the integration strength between the core 2 of the retaining wall 1 and the RC wall 5 is set by adjusting the pitch of the studs 8 serving as the shear key provided on the core 2, so that the components of the composite basement wall 7 can be integrated. The strength can be reliably set by a simple method.
[0015]
And in this embodiment, the above-mentioned synthetic underground wall 7 is constructed in the following steps. First, a mountain retaining wall 1 made of SMW as shown in FIG. 1 is constructed underground in the same manner as in the prior art, and the ground surface inside the mountain retaining wall 1 is excavated as shown in FIG. The beam 3 and the slab 4 are constructed, and as shown in FIG. 3, after excavating to a level slightly deeper than B1FL, the outer peripheral beam 3 and the slab 4 on the first basement floor are constructed. At this time, the outer peripheral beam 3 on the first basement floor is integrated with the core 2 of the retaining wall 1 via the stud 8.
[0016]
In the conventional method, the next excavation is continuously performed. In this embodiment, the RC wall 5 is constructed on the first basement floor as shown in FIG. 4 prior to the next excavation. As described above, since the retaining wall 1 and the RC wall 5 are provided as overlapping walls on the first basement floor, the studs 8 are not integrated here, but in any case, the RC wall is provided inside the retaining wall 1. 5, the secondary moment of area there is greatly increased, the rigidity is increased, and the bending moment generated in the retaining wall 1 during the next excavation can be reduced.
[0017]
Then, as shown in FIG. 5, after the next excavation is performed to a level slightly lower than the second basement floor, the outer peripheral beam 3 and the slab 4 on the second basement floor are constructed. At this time, the outer peripheral beam 3 is integrated with the core material via the studs 8. However, as described above, since the integration strength is higher than the second floor below the third floor below the basement, the pitch of the studs 8 is higher than that of the upper floor. Also dense. Further, when the outer peripheral beam 3 is constructed, the lower portion thereof is additionally struck to the excavated bottom surface (so-called lower end shank), and the extra striking portion 3a is similarly integrated with the core 2 by the stud 8.
[0018]
Next, as shown in FIG. 6, the RC wall 5 is provided on the second basement floor with the stud 8 integrated with the core material 2 of the retaining wall 1, and the composite basement wall 7 is constructed up to the second basement floor. Subsequently, as shown in FIG. 7, the next excavation is performed to the foundation level, and the underground skeleton is completed by constructing the third basement floor and the foundation skeleton.
[0019]
As described above, by excavating the ground stepwise while constructing the composite underground wall 7 by superimposing or integrating the retaining wall 1 and the RC wall 5, the conventional temporary retaining Compared to the case where the wall 1 and the RC wall 5 as the main basement wall are individually provided, the wall thickness of the RC wall 5 can be reduced by the amount of the strength of the retaining wall 1 and the amount of rebar can be reduced, Further, by constructing the composite underground wall 7 prior to excavation, the bending rigidity is increased as compared with the case of the retaining wall 1 alone, and the deformation is reliably suppressed. The required wall thickness and the cross section of the core material 2 can be reduced as compared with the case where they are provided. Therefore, according to the above-mentioned construction method, the required thickness of the composite underground wall 7 can be sufficiently reduced as compared with the total thickness of the ridge wall 1 and the RC wall 5 in the conventional upside-down construction method. Not only is it advantageous in terms of cost compared to the conventional method, it can be applied even when there is no room on the site, and it is possible to secure a large effective space on the basement floor, which is extremely effective. Of course, since the retaining wall 1 is used as a part of the main basement wall, there is no need to remove it after completion.
[0020]
In addition, by increasing the cross section of the lower part of the outer beam 3 provided integrally with the RC wall 5 to increase the cross section, the outer wall 3 can stably support the retaining wall 1 over a wide range. Since the deformation of the retaining wall 1 at the time can be suppressed more reliably, it is possible to further reduce the wall thickness of the retaining wall 1 and the cross section of the core material 2, and it is necessary to provide a temporary installation conventionally required. It is also possible to eliminate the need for an intermediate beam or the oblique beam 12 as shown in FIG.
[0021]
Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and the scale and form of the underground skeleton to be constructed, the state of the ground, and other conditions as appropriate. Design changes may be made. For example, the retaining wall 1 is not limited to the SMW, and a retaining wall of another structure, such as an H-section steel sheet pile method, may be used as long as the RC wall 5 can be integrated with the core material 2. Can be adopted. Also, the configuration for integrating the retaining wall 1 and the RC wall 5 and the configuration for adjusting the integration strength are not limited to the adjustment of the studs 8 and the pitch thereof, and appropriate configurations can be considered. The range in which the retaining wall 1 and the RC wall 5 are integrated or simply overlapped, the wall thickness of each part of the RC wall 5, and the like are appropriately set in consideration of the stress and other conditions generated in each part of the composite basement wall 7. Just do it. In addition, as an example of the construction procedure, excavation of the lower floor is exemplified after the underground outer wall of the floor. On a deep floor, a more rational construction plan can be obtained by appropriately combining the two, such as excavating the lower floor after the construction of the underground outer wall.
[0022]
【The invention's effect】
The invention according to claim 1 is to integrally provide a reinforced concrete wall inside a retaining wall and construct them as a composite underground wall. In particular, after constructing the retaining wall, the ground inside the retaining wall is stepped. While excavating, a reinforced concrete wall is provided inside the retaining wall exposed at that stage when a certain stage is excavated, and a composite underground wall is constructed. The wall thickness of the RC wall can be reduced by as much as the strength of the wall can be expected, and since the retaining wall is reinforced by the RC wall, the required wall thickness and core material cross-section can be reduced compared to the case where the wall is simply provided temporarily. Therefore, the total thickness of the composite basement wall can be made sufficiently thinner than the total thickness of the conventional temporary retaining wall and the permanent reinforced concrete wall, and the retaining wall is used as a part of the permanent underground wall. Removal is not necessary. It is extremely effective and reasonable compared to just reverse out method of.
[0023]
According to the invention of claim 2, when constructing the composite underground wall of each step, the integrated strength of the core material of the retaining wall and the reinforced concrete wall is determined according to the stress distribution expected to occur in each part of the composite underground wall. Is set, the wall thickness and strength of each part of the synthetic underground wall can be optimally set, and waste that would be unnecessarily large can be eliminated.
[0024]
According to the third aspect of the present invention, the integration strength between the core material of the retaining wall and the reinforced concrete wall is set by adjusting the pitch of the stud as a shear key provided on the core material. Can be reliably set by a simple method.
[0025]
According to the fourth aspect of the present invention, the excavation of the next stage is performed after the lower part of the outer peripheral beam provided integrally with the reinforced concrete wall of a certain stage is excavated to the excavated bottom surface of the relevant stage. The retaining wall can be stably supported over a wide range and its deformation can be reliably prevented, so that the wall thickness and core cross section of the retaining wall can be further reduced. It becomes possible to eliminate the need for the inclined beams.
[Brief description of the drawings]
FIG. 1 shows an embodiment of the present invention, and is a view showing a state where a retaining wall is provided.
FIG. 2 is a diagram showing a state where an outer peripheral beam and a slab on the first floor are constructed.
FIG. 3 is a diagram showing a state in which an outer peripheral beam and a slab on the first basement floor are constructed.
FIG. 4 is a diagram showing a state where a composite basement wall of the first basement is constructed.
FIG. 5 is a view showing a state in which an outer peripheral beam and a slab on the second basement are constructed.
FIG. 6 is a diagram showing a state where a composite basement wall on the second basement is constructed.
FIG. 7 is a diagram showing a state where excavation is completed.
FIG. 8 is a view showing an outline of a conventional reverse striking method, showing a state in which a retaining wall is provided.
FIG. 9 is a diagram showing a state in which an outer peripheral beam and a slab on the first floor are constructed.
FIG. 10 is a diagram showing a state where an outer peripheral beam and a slab on the first basement floor are constructed.
FIG. 11 is a view showing a state in which an outer peripheral beam and a slab on the second basement are constructed.
FIG. 12 is a diagram showing a state where excavation is completed and an underground wall on the first basement is constructed.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Retaining wall 2 Core material 3 Peripheral beam 3a Additional striking part 4 Slab 5 Reinforced concrete wall (RC wall)
7 Synthetic basement wall 8 Stud (Shiakey)

Claims (4)

When constructing a composite underground wall with a reinforced concrete wall integrally provided inside the mountain retaining wall, after constructing the mountain retaining wall, excavating the ground inside and gradually excavating a certain step A method for constructing a composite underground wall, comprising: providing a reinforced concrete wall inside a retaining wall exposed to the step, constructing a composite underground wall of the step, and then excavating the next step. When constructing the composite basement wall of each step, the integrated strength of the core material of the retaining wall and the reinforced concrete wall is set according to the stress distribution expected to occur in each part of the composite basement wall. The method for constructing a synthetic underground wall according to claim 1. 3. The method according to claim 2, wherein the setting of the integration strength between the core material of the retaining wall and the reinforced concrete wall is performed by adjusting a pitch of a stud as a shear key provided on the core material. The composite underground wall according to claim 1, 2, or 3, wherein the lower part of the outer peripheral beam provided integrally with the reinforced concrete wall of a certain step is additionally struck to the excavation bottom of the step, and then the next step is excavated. Construction method.

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