JP2572680B2 - Underground structure by reverse strike method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an underground reverse beating method.

(Conventional technology and problems to be solved by the invention) In the conventional underground excavation method, the reverse striking method is adopted in which the construction of the underground part is advanced from the upper floor to the lower floor, contrary to the general method. is there.

In this method, after a predetermined number of trussed pillars are buried in an excavated part where a mountain retaining wall or the like is formed in advance, a steel reinforced concrete pillar, beam and floor are installed on the basement floor while receiving a load with these trussed pillars. Are constructed sequentially from top to bottom in parallel with excavation.

However, in the case of the conventional reverse striking method, it is impossible to receive the earth pressure from the retaining wall by using only steel columns and beams because of insufficient compressive strength, or the cross sections of the columns and beams are made unnecessarily large. Because of the necessity, the concrete for the pillars, beams and floor had to be poured simultaneously in parallel with the excavation.

Performing this concrete work requires complicated and time-consuming work for pillars, beams, and floor formwork and rebar arrangements, and it also makes it difficult to carry out excavated earth and sand below because concrete is put into place. There were drawbacks.

An object of the present invention is to provide an underground structure by a reverse striking method capable of solving such a conventional problem.

(Means for Solving the Problems) In order to achieve the above object, in the underground structure by the reverse hitting method according to the present invention, as a cutting beam receiving earth pressure from the retaining wall, a steel frame material filled with concrete is used. It is characterized in that this steel frame concrete beam can be used as a permanent beam, and the lowest one of the cut beams is embedded in the upper part of the foundation beam and integrated. is there.

(Embodiment) Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.

FIGS. 1 to 5 show an embodiment of the present invention. As shown in FIGS. 1 and 2, in the underground reverse excavation method according to the present embodiment, as a construction procedure of a valley, In the same manner as in the prior art, a retaining wall 1 such as a continuous wall, a sheet pile or the like is formed in advance, and a predetermined number of timber pillars 3 are buried in an excavated portion 2 surrounded by the retaining wall 1, and soil and sand are removed. Excavation is performed, and the bulging members 4 and the cutting beams 5 are sequentially constructed from the upper floor to the lower floor in parallel with the excavation work.

Here, the cutting beam 5 according to the present embodiment connects a pair of channel steels 7 with a lower portion of the pair of channel steels 7 so as to have a hollow portion 6 inside as shown in FIG. It is formed of a connection steel plate 8 which also serves as a formwork, and has a steel frame portion in which an opening 9 for placing concrete is formed at the upper part.

Then, after arranging such a steel frame portion at a predetermined position between the straight columns 3 or between the straight columns 3 and the protruding members 4, concrete 10 is poured into the hollow portion 6 to form a permanent steel concrete beam. The cross section is set so that it can be used.

In addition, the cutting beam 5 may be formed as a steel concrete beam in advance and then carried into the site.

Also, as shown in FIG. 3, the straight pillar 3 is not formed of a normal single steel frame material, but is formed as a steel pipe concrete pillar having a concrete 10 filled therein. The cross section is set so that it can be used as a pillar.

Then, as shown in FIG. 4, the pair of trussed pillars 3 and the cutting beams 5 are joined at a corresponding position of the trussed pillars 3 by a pair of gusset plates.
The gusset plate 11 and the end of the cutting beam 5 are joined together by bolts 12. In FIG. 4, only the cut beam 5 in one direction and the joint are shown, and the joints with the cut beam 5 from the other three directions are omitted for convenience, but these joints also have the same configuration. .

Moreover, the above-mentioned belly material 4 in the present embodiment may be used as a permanent beam.

In this embodiment, as shown in FIG. 1, the bulging member 4 and the cutting beam 5 are sequentially constructed from the upper floor to the lower floor in parallel with the excavation work. After being disposed, excavation is performed to a depth necessary for forming a foundation beam below the earth beam while bearing earth pressure by the cutting beam 5.

In forming the foundation beam 15 as shown in FIG. 5 and FIG. 6, predetermined reinforcing bars 16 and formwork are performed in a state where the cutting beam 5 is arranged at the lowermost portion above the foundation beam 15. In addition, a foundation beam 15 made of a steel-framed reinforced concrete structure in which the cutting beam 5 is embedded and integrated is constructed.

In the present embodiment having such a configuration, the cross-section design is made so that the straight columns 3 and the cutting beams 5 which have been conventionally used only as temporary materials are made of steel-frame concrete, and can be used as the main columns and beams. Because of its high rigidity and compressive strength, it is possible to resist earth pressure and the like only with these columns and beams, and it can stand up without forming a concrete floor beam. Can be carried out very efficiently.

In addition, similarly, the problem of complicated beam and floor formwork and rebar arrangement work due to the reverse striking method as in the past has been resolved, shortening the excavation time, and labor saving because no dismantling work is required. Can be achieved.

Furthermore, the lowermost cutting beam 5 can be used also as a part of the foundation beam 15, so that it is rational. Also, since the foundation beam 15 is made of steel reinforced concrete, the amount of the reinforcing bar 16 at the upper end is reduced. It becomes possible.

In addition to the above embodiment, the cross-sectional configuration of the cutting beam 5 can be appropriately set to a cross-sectional configuration. Also, for the straight columns 3, circular steel pipes or H-shaped steels are used. In this case, the present invention is not limited to the above-described embodiment. For example, various modifications can be made without departing from the gist of the present invention. It goes without saying that examples are possible.

(Effects of the Invention) The present invention is configured as described above, and since it is possible to use a permanent steel concrete beam as a cutting beam without placing floor concrete or the like, the strength is high and a large excavation space can be taken. The lower excavated soil can be carried out very efficiently.

Further, since the work of arranging the beams and floors during excavation, the arrangement of the reinforcing bars, and the dismantling work as in the prior art are eliminated, the construction period can be shortened and the complexity can be eliminated.

Further, the lowermost cut beam can be used as a part of the foundation beam, so that it is rational, and since it becomes a steel-frame reinforced concrete foundation beam, it is possible to reduce the amount of upper rebar.

[Brief description of the drawings]

1 to 6 show an embodiment of the present invention. FIG. 1 is a conceptual diagram showing a configuration of a shoring by a reverse striking method according to the present embodiment. FIG. 2 is a conceptual plan view of FIG. FIGS. 3 and 4 are cross-sectional views showing the structure of the cut beam, FIGS. 4 (a) and 4 (b) are explanatory views each showing a joint between the straight column and the cut beam, and FIG. FIG. 6 is a conceptual diagram showing the configuration after the beam is formed, and FIG. 6 is a sectional view showing the configuration of the foundation beam. 1 ... Retaining wall, 3 ... Structural pillar, 4 ... Wrapped material, 5 ... Section beam, 6 ... Hollow section, 10 ... Concrete, 15 ... Foundation beam, 16 ... Rebar.

Claims (1)

(57) [Claims] An underground construction method using a reverse striking method, wherein a steel concrete beam is permanently used as a cutting beam, and the lowest one of the cutting beams is buried in an upper part of a foundation beam and integrated. Construction.