JPH04149321A - Underground structure by reverse placing method - Google Patents

Abstract

PURPOSE:To facilitate delivery of sediment by using reinforced concrete beams to be used for permanent work as struts in order from upper floor in parallel with drilling work, and burying the lowest strut in the upper of the inside of a footing beam for integral construction. CONSTITUTION:A predetermined number of horizontal studs 3 formed as steel pipe concrete pillars, in which inside concrete is filled, are buried in a drilling part 2 surrounded by retaining wall 1. Next, a reinforcement part of each strut 5 is located in a predetermined position between the horizontal studs 3 or between the horizontal studs 3 and walling members 4, and thereafter, concrete 10 is placed in a hollowing part 6 of the reinforcement of the strut 5 to use the strut 5 as reinforced concrete beams for the permanent work. In parallel with the drilling work, members 4 and the struts 5 are constructed in order from the upper floor to the lower floor. Next, the lowest strut 5 is buried in the upper of the inside of the footing beam 15 to be unified. A construction period is thereby shortened.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an underground inversion construction method.

(Problems to be solved by conventional technology and invention) In the conventional underground excavation method, contrary to the general practice, a reverse construction method is adopted in which the underground section is constructed from the first floor to the lower floor. be.

This construction method involves burying a predetermined number of structural pillars in an excavated area with retaining walls, etc. formed in advance, and then using these structural pillars to receive the load while constructing the permanent steel-framed reinforced concrete columns, beams, and floors of the underground floor. In parallel with the excavation, they are constructed sequentially from top to bottom.

However, in the case of the conventional reverse construction method, it is impossible to use only steel columns and beams due to insufficient compressive strength to receive the earth pressure from the retaining wall, or the columns and beams alone do not have enough compressive strength.

Because the cross section of the beam needs to be unnecessarily large.

It was necessary to pour concrete for the columns, beams, and floor at the same time as the excavation.

In order to carry out this concrete work, the work of constructing and arranging reinforcement for columns, beams, and floors is complicated and time-consuming.Furthermore, since the floor concrete is poured, it becomes difficult to carry out the excavated earth and sand below. There was a drawback.

It is an object of the present invention to solve such conventional problems and provide an underground structure using the vine reverse construction method.

(Means for Solving the Problem) In order to achieve the above object, in the underground structure using the reverse pouring method according to the present invention, a steel frame material filled with concrete is used as a strut to receive earth pressure from the retaining wall. The steel-framed concrete beam is used as a permanent beam for suspension, and the lowest part of the strut is buried in the upper part of the foundation beam to integrate it. be.

(Example) Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

Figures 1 to 5 show one embodiment of the present invention, and as shown in Figures 1 and 2, in the underground reverse excavation method according to this embodiment, the construction procedure for pile stop is , as in the past, a retaining wall 1 such as a continuous wall or sheet pile is formed around the surrounding area in advance, and a predetermined number of structural pillars 3 are buried in the excavated part 2 surrounded by the upper retaining wall 1. The earth and sand are excavated, and in parallel with the excavation work, the raising member 4. The struts 5 are constructed sequentially from the upper floor to the lower floor.

Here, the strut 5 according to this embodiment connects a pair of channel steels 7.7 and the lower portions of the pair of channel steels 7 so as to have a hollow portion 6 inside as shown in FIG. Connecting steel plate 8 that can also be used as formwork
It has a steel frame part in which an opening 9 for pouring concrete is formed in the upper part.

Then, after placing the steel frame part at a predetermined position between the structural pillars 3 or between the horizontal pillars 3 and the raised members 4, concrete LO is poured into the hollow part 6 to form a permanent steel concrete beam. The cross section has been set so that it can be used.

Note that the strut 5 may be formed as a steel concrete beam in advance and then transported to the site.

In addition, as shown in Fig. 3, the structural pillar 3 is also formed as a steel pipe concrete column filled with concrete 10 inside, instead of a normal single steel frame, and the main column pillar 3 is also a permanent pillar. The cross section has been set so that it can be used as a pillar.

Therefore, the connection between the horizontal straight pillar 3 and the strut 5 is achieved by a pair of plates l set at corresponding positions on the horizontal straight pillar 3, as shown in FIG.
The gusset plate 11 and the end of the strut 5 are connected with bolts 12. In addition, in Fig. 3, only the joints with the struts 5 in one direction are shown, and the joints with the struts 5 from the other three directions are omitted for convenience, but these joints also have the same configuration. Become.

Further, the above-mentioned raised material 4 in the four-piece embodiment may be used as a beam for the permanent installation.

Therefore, in this embodiment, as shown in FIG. 1, the raising members 4 and struts 5 are sequentially constructed from the second floor to the F floor in parallel with the excavation work, and the lowest strut 5 is Once installed,
While bearing the earth pressure by the strut 5, excavation is carried out to a depth necessary to form a foundation beam under the strut 5.

As shown in FIGS. 5 and 6, when forming the foundation beam 5, the lowermost strut 5 is placed on the top of the foundation beam 15, and a predetermined reinforcement arrangement is performed.6. Formwork work is carried out, and the struts 5 are buried and an integrated steel-frame reinforced concrete foundation beam 15 is constructed.

In this embodiment with such a configuration, the horizontal straight columns 3 and struts 5, which were conventionally used only as temporary construction materials, are made of steel-framed concrete, and the cross-sectional design is designed so that they can be used as permanent columns and beams. Because of their high rigidity and compressive strength, these columns and beams alone can resist earth pressure, etc., and because they stand on their own without forming concrete floor beams, there is a large open space and the excavated earth and sand below. can be carried out very efficiently.

Similarly, the problem of the conventional reverse casting method, which requires complicated formwork and reinforcing work for beams and floors, is resolved, reducing excavation time.Furthermore, there is no need for demolition work, resulting in labor savings. can be achieved.

Furthermore, the lowermost strut 5 can also be used as a part of the foundation beam 15, so it is rational, and since it becomes the foundation beam 15 of steel reinforced concrete construction, the reinforcing bar 1 at the upper end
It becomes possible to reduce the amount of 6.

It should be noted that the cross-sectional configuration of the strut 5 may be any other appropriate cross-sectional configuration in addition to the above-mentioned embodiments, and the horizontal straight column 3 may also be made of a circular steel pipe or H-beam steel. The present invention is not limited to the above embodiment, and various modifications may 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 constructed as described above, and since the existing steel concrete beam can be used as a strut without placing concrete floor etc., the strength is high and the excavation space can be large. The excavated earth and sand below can be carried out very efficiently.

In addition, since there is no need for constructing formwork for beams and floors during excavation, reinforcing work, or demolition work, which was required in the past, the construction period can be shortened and complexity can be eliminated.

Furthermore, since the lowest sill beam can be used as a part of the foundation beam, it is reasonable, and since it is a foundation beam for a steel reinforced concrete structure, reducing the amount of reinforcing bars at the top can be done without Become.

[Brief explanation of drawings]

1 to 6 show an embodiment of the present invention, FIG. 1 is a conceptual diagram showing the structure of a heap using the reverse hammering method according to this embodiment, and FIG. 2 is a conceptual plan view of FIG. 1. Figures 3 and 3 are cross-sectional views showing the structure of the struts, Figures 4 (a) and 4 (b) are explanatory diagrams showing the joints between the structural pillars and the struts, and Figure 5 is the foundation. FIG. 6 is a conceptual diagram showing the structure after the beam is formed, and FIG. 6 is a sectional view showing the structure of the foundation beam. 1... Earth retaining wall, 4... Raising material. 5... Stray beam, 10... Concrete. 15...Foundation beam, 3...Structure pillar, 6...Hollow part, 6...Reinforcement bar.

Claims (1)

[Claims] An underground structure using the reverse pouring method, characterized in that a permanently installed steel concrete beam is used as a strut, and the lowest of the struts is buried and integrated into the upper part of the foundation beam.