JPS63226494A - Method of shaft construction - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] "Industrial Application Field" This invention relates to a method for constructing a shaft, particularly for excavating the inside of a cylindrical structure constructed by connecting each element of an underground continuous wall with rigid joints. In particular, it concerns the method of constructing a vertical shaft.

``Prior art, problems to be solved by invention'' In the conventional construction of vertical shafts using underground continuous walls and steel pipe sheet piles, the connections between each element are weak, and each element bears the burden of supporting force. Therefore, an internal main body wall is required for a vertical shaft with a permanent structure, and the installation of supports such as struts and hoods is required at the same time as the internal excavation, which results in poor work efficiency and The internal displacement becomes larger at deeper depths,
The water-stopping properties have deteriorated, and in addition, it is necessary to increase the root length of the earth retaining wall in order to secure the passive soil pressure reaction force in the flooring section, and to ensure the stability of the ground against boiling, heaving, and swell. There were some issues, such as ground improvement that may be required.

On the other hand, a construction method is known in which each element of an underground continuous wall is connected with rigid joints to form an integrated cylindrical structure, and the inside of the structure is excavated. The cross-section of the horizontal box in this state receives large lateral pressure (earth pressure + water pressure difference), resulting in a large cross-sectional force, which has the disadvantage of being difficult to adapt to deep excavations.

"Means for Solving the Problems" In order to solve the above-mentioned conventional problems, the present invention connects each element of an underground continuous wall with a rigid joint and excavates the inside of an integrated cylindrical structure underwater. By creating a bottom slab by pouring underwater concrete at the bottom, it is possible to excavate stably and efficiently while suppressing the generation of external forces by using internal water pressure, and it is possible to improve the ground without taking a large root length. In addition to being able to safely construct the bottom slab without having to perform any This paper proposes a construction method that allows the construction of high shafts.

"Embodiments" Below, embodiments of the present invention shown in the drawings will be described.
First, each element of the underground continuous wall that will become the main wall of the shaft 1.
1 are rigidly connected to each other by lap joints of horizontal reinforcing bars, etc., to create an integral cylindrical structure 2 with a box cross section (Fig. 1.2).

Then, as shown in FIG. 3, the inside of the cylindrical structure 2 is sequentially filled with water while being excavated underwater, and the excavation is carried out while suppressing the external force due to lateral pressure and lift using the integral cylindrical structure and internal water pressure.

After excavation to a predetermined depth is completed, as shown in FIG. 4, the inner surface of the bottom of the cylindrical structure 2 is roughened and cleaned, and then underwater concrete is poured to create a bottom slab (temporary) 3.

In the construction of this bottom slab 3, as shown in Fig. 6, the ground below the tubular structure 2 is enlarged and excavated, and the gravity type is made into unreinforced concrete using the own weight of the poured concrete and the plug effect of the enlarged excavation part. Alternatively, as shown in FIG. 7, a reinforced version type can be adopted in which an earth anchor 4 is driven into the bottom ground in advance, reinforcing bars are arranged, and then concrete is poured to maintain the strength.

Next, as shown in FIG. 4.5, strut supports 5 are constructed underwater between the inner surfaces of the cylindrical structure 2.

For example, as shown in Fig. 8.9, a plurality of these strut supports 5 are installed in one piece at a predetermined interval vertically between the left and right vertical steel members 6, and jacks 7 are installed at both ends of each strut support 5. This is then erected along vertical guides 8, 8 which are provided in advance to face the inner surface of the element 1.1 of the underground continuous wall, and the jacks 7 are successively extended and fixed on the ground by pressure.

In this state, the water in the cylindrical structure 2 is drained, and the erection shaft is completed.

"Effects of the Invention" As described above, according to the present invention, each element of an underground continuous wall is connected with a rigid joint to construct an integrated cylindrical structure,
Since the inside of this cylindrical structure is excavated underwater, it is possible to use this cylindrical structure as it is as the main body of the shaft without requiring the construction of a separate main body wall, and the internal water pressure reduces and offsets the side pressure and uplift force. It is possible to excavate safely and efficiently using a machine without concurrently carrying out restraint and shoring construction.

In addition, since the bottom slab is created by pouring underwater concrete at the bottom while the inside is filled with water, there is no need for ground improvement to stabilize the ground at the bottom of the excavation, and the rooting length can be shortened.

In addition, only the struts are required for reinforcement, and since the excavated diameter strut supports are erected underwater, construction can be simplified and made more efficient by precasting.

Therefore, with this invention, it is possible to achieve deeper shaft construction and economical construction.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway perspective view of a shaft constructed according to the present invention, Figs. 2 to 5 are longitudinal sectional front views showing the construction status in the order of steps, and Figs. 6 and 7 are different bottom slabs. FIG. 8 is a partial front view of the strut support used in the present invention, and FIG. 9 is a plan view showing the construction state. l... Underground continuous wall element, 2... Cylindrical structure, 3...
・Bottom slab, 5... strut support. Patent applicant: Maeda Kensetsu Kogyo Co., Ltd. Agent: Minoru Fujii, −＼
'Kuji, n

Claims (1)

[Claims] Each element of the underground continuous wall is connected with rigid joints to construct an integrated cylindrical structure, and the inside of this cylindrical structure is excavated underwater to create a bottom slab by pouring underwater concrete at the bottom. A shaft construction method characterized by erecting strut supports between the inner surfaces and then draining the interior.