JPH04238919A - Construction of underground beam - Google Patents

Abstract

PURPOSE:To effectively construct the above underground beam for the underground portion of an existing facility by a method in which a sleeve is pressingly penetrated from one vertical pit to the other vertical pit, reinforcing bars are set inside, and concrete is packed into it. CONSTITUTION:Vertical pits 10A and 10B are formed in both ends of an underground beam 4 to be constructed. While connecting precast concrete sleeves 15A and 15B, they are penetrated from one vertical pit 10A to the other vertical pit 10B into the ground. When the tips of a series of the sleeves 15A and 15B reach the other vertical pit 10B, the inside of the sleeves 15A and 15B is excavated to form a cave, reinforcing bars are set in the cave, and concrete is packed into it. The underground beam 4 can thus be constructed for the underground portion of the existing facility while using the facility.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for constructing underground beams, and is particularly suitable for use when installing underground beams in the underground portion of existing above-ground facilities while using them as they are. Regarding construction methods for underground beams.

0002

[Prior Art] In recent years, for the purpose of effectively utilizing the space above existing buildings on the ground or structures such as railways and roads, existing facilities (in the illustrated example It is being considered to cover the upper part of the railway (railroad tracks) with an artificial ground 1 consisting of a large-span truss, and to construct new buildings and structures on the artificial ground 1. Various construction methods are being proposed for constructing such artificial ground 1 while using existing facilities as they are (in the illustrated example, without stopping railway operations).

0003

[Problem to be Solved by the Invention] By the way, when the above-mentioned artificial ground 1 is installed above an existing facility, as shown in FIG.
As shown in , it is necessary to install pillars 2 to support the artificial ground 1 and piles 3 connected to these pillars 2 around the existing facility, as well as to ensure that the pile heads of these piles 3 (
An underground beam 4 for connecting the bases of the columns 2 underground is also essential. However, these underground beams 4 must be installed underground while using the existing facilities as they are, and the work space required to construct such underground beams 4 must be constructed around the existing facilities. Generally, it is difficult to secure a sufficient amount of soil under such conditions, and therefore, the reality is that no effective means for constructing underground beams 4 under such conditions has yet been provided.

The present invention has been made in view of the above circumstances, and provides an effective construction method for constructing underground beams in the underground portion of the existing facility while using the existing facility, for example, when constructing an artificial ground above the existing facility. The purpose is to provide a method.

[0005]

[Means for Solving the Problems] The present invention is a method of constructing an underground beam made of reinforced concrete underground, in which the method is carried out from one side of a vertical shaft provided at both ends of the underground beam to be constructed. , Sleeve bodies made of precast concrete are sequentially connected and pressed into the ground toward the other shaft, and when the tips of the series of sleeve bodies reach the other shaft, the insides of the sleeve bodies are excavated to create a cavity. The method is characterized in that reinforcing bars are placed inside the sleeve body and then filled with concrete to form an underground beam having the sleeve body as the outer layer.

[0006]

[Example] Examples of the method of the present invention are shown below in Figures 1 to 5.
This will be explained with reference to. FIG. 1 shows a state in which an underground beam 4 is being constructed in the underground portion of the railway track when an artificial ground 1 as shown in FIG. 6 is provided above the existing railway track.

In this case, the piles 3 are first constructed, and vertical shafts 10A and 10B are respectively provided above the pair of piles 3 and 3 to which both ends of the underground beam 4 to be constructed are connected. The pile 3 may be of any suitable type, and may be, for example, a cast-in-place concrete pile. In addition, prior to excavating the shafts 10A and 10B, a retaining wall 11 made of sheet piles is provided, but one shaft 1
A reaction wall 12 made of H steel piles is provided on the wall of 0A (the left shaft in FIG. 1).

By taking the reaction force from the reaction wall 12, the sleeve body 15 is removed from the one shaft 10A.
A is forced into the ground by a hydraulic jack 13 toward the other shaft 10B. Further, once the sleeve body 15A is press-fitted, another sleeve body 15B is connected to the rear part thereof and further press-fitted. Note that the reference numeral 14 in FIG. 1 indicates a sleeve body 15A, which is provided on the upper part of the pile 3 and is to be press-fitted.
This is a temporary base plate for supporting and sliding 15B.

These sleeve bodies 15A and 15B are made of precast concrete, which will eventually become the outer layer of the underground beam 4, and the sleeve body 15 is press-fitted first.
As shown in FIGS. 2 and 3, A has a cutting edge 16 formed at the tip and a fitting groove 17 formed at the rear for connecting another sleeve body 15B. As shown in FIGS. 4 and 5, another sleeve body 15B connected to the rear part of the sleeve body 15A can fit into the fitting groove 17 of the sleeve body 15A at its tip instead of the blade opening 16. The sleeve body 15A is formed in the same manner as the sleeve body 15A described above except that the fitting convex portion 18 is formed. Then, the sleeve body 15A and the sleeve body 15B
, and the sleeve body 15B are firmly connected in a straight state as a whole by fitting the fitting groove 17 and the fitting protrusion 18 and fastening them with bolts.

As described above, the sleeve body 15A is press-fitted from the inside of one shaft 10A toward the other shaft 10B using the hydraulic jack 13, and the other sleeve body 15B is inserted into the rear part of the sleeve body 15A.
are connected and further press-fitted, and this process is repeated one after another until the tips of the series of sleeve bodies reach the other shaft 10B. After that, the hydraulic jack 13 was removed, the inside of the series of sleeve bodies was excavated to form a cavity, beam reinforcing bars were arranged inside, and the beam reinforcing bars were connected to pile reinforcing bars and column reinforcing bars as necessary. After that, concrete is poured into the inside of the sleeve body and the pile head. Thereby, the underground beam 4 is formed integrally with the head of the pile 3. Therefore, as shown in FIG. 6, a pillar 2 may be constructed on top of the pile 3, and the artificial ground 1 may be constructed while being supported by the pillar 2.

According to the above construction method, when constructing the underground beam 4, the vertical shafts 10A and 10B are installed around the existing facility.
There is no need to excavate any other parts from the ground, and therefore the underground beam 4 can be constructed while using the existing facilities as they are. Of course, since the sleeve bodies 15A, 15B... are connected and press-fitted into the ground, no cavities will be created in the ground, and there is no risk of ground subsidence or the like.

As should be clear from the above description, the horizontal cross-sectional area of the shaft 10A may be set so that the sleeve bodies 15A, 15B can be placed horizontally with the sleeve bodies 15A and 15B facing in the press-fitting direction. , 15B are made sufficiently short, the horizontal cross-sectional area of the shaft 10A can be made slightly larger than the cross-sectional area of the pile 3, similar to the shaft 10B, and there is enough work space around the existing facility. It can also be applied to narrow sites where it is impossible to secure. Conversely, if sufficient work space can be secured around the existing facility, it is possible to increase the horizontal cross-sectional area of the shaft 10A and use a long sleeve body, and in that case, the connection points between the sleeve bodies This has the advantage of being able to reduce the amount of work and improve work efficiency. but,
If a sleeve body is too long, it will be difficult to transport and handle it, so it is sufficient to take this into account and set the sleeve body to an optimum length.

[0013]

[Effects of the Invention] As explained above, the present invention enables a series of precast concrete sleeve bodies to be connected in sequence in one shaft and press-fitted into the ground toward the other shaft. The tip of the sleeve body reaches the other shaft, and an underground beam is formed by arranging reinforcement inside the series of sleeve bodies and filling it with concrete, so you can simply install a shaft around the existing facility. For other parts, there is no need to excavate from the ground. Therefore, it is possible to construct underground beams while using existing facilities as is, and since no cavities are created underground, ground subsidence etc. can be prevented. There is no fear that this will occur,
Moreover, by using a sufficiently short sleeve body, the horizontal cross-sectional area of the shaft can be small, so it has the advantage of not requiring much work space, and is suitable for use when constructing artificial ground above existing facilities. It is.

[Brief explanation of the drawing]

FIG. 1 is an elevational sectional view showing a state in which an underground beam is being constructed by the method of the present invention.

FIG. 2 is a side sectional view of a sleeve body used in the same method.

FIG. 3 is a front view of the sleeve body.

FIG. 4 is a side sectional view of another sleeve body used in the same method.

FIG. 5 is a front view of the sleeve body.

FIG. 6 is a conceptual diagram when an artificial ground is provided above an existing railway line.

[Explanation of symbols]

4 Underground beam 10A, 10B Vertical shaft 12 Reaction wall 13 Hydraulic jack 15A, 15B Sleeve body.

Claims (1)

[Claims] Claim 1: A method for constructing a reinforced concrete underground beam underground, the method comprising: inserting a precast concrete sleeve body from one of vertical shafts provided at both ends of the underground beam to be constructed; The sleeve bodies are pressed into the ground toward the other shaft while being connected one after another, and when the tips of the sleeve bodies reach the other shaft, the insides of the sleeve bodies are excavated to form a cavity, and then the sleeve bodies are pressed into the ground toward the other shaft. A method for constructing an underground beam, characterized by forming an underground beam having the sleeve body as an outer layer by arranging reinforcing bars inside and filling the concrete with concrete.