JPH10159074A - Execution method of underground structure in cut and cover tunneling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the execution method of an underground structure, in which resources are utilized effectively and operating efficiency is improved. SOLUTION: Hold-down forms 3 for liquefied treated soil 5 are installed onto an excavation ground, back-filling by the liquefied treated soil 5 is conducted prior, to the building of the underground structure, and the hold-down forms are removed after the solidification of the liquefied treated soil. A side face formed of the solidified liquefied treated soil 5 is used as the outer forms of the underground concrete structure at that time, and reinforcing bars and inner forms for the structure are installed and concrete is placed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for constructing an underground structure in an open-cutting method.

[0002]

2. Description of the Related Art Conventionally, for example, when a box culvert is constructed underground as an underground structure, as shown in FIG. 3, (a) As a retaining wall a, a sheet pile such as a steel sheet pile or a PC sheet pile is driven into the ground. In parallel with the excavation, cut beams and ridges will be installed on the inner surface of the sheet pile wall for soil retention. (B) After excavation and earth retaining are completed, an outer formwork b, a waterproof sheet c, a reinforcing bar, an inner formwork, and the like are installed, and concrete is cast to construct an underground structure A such as a box culvert. However, at the time of backfilling after the construction of the underground structure, the outer formwork will be buried. (C) After the construction of the underground structure, the space between the structure and the retaining wall is backfilled with mountain sand or fluidized soil d.

[0003] In the figure, e is discarded concrete, and f is improved ground.

[0004]

In the above-mentioned conventional method, the outer formwork is buried in the step (b), and resources are wasted. Until the backfill is completed, the waterproof sheet installed on the outer wall of the underground structure may peel off, cut beams,
At the time of removal of the bulging, there is a concern that the waterproof sheet may be damaged by an unexpected falling object such as earth and sand adhered thereto.

Further, in the case of backfilling with mountain sand or the like in the step (c), settlement is expected. (C)
In the case of backfilling with fluidized treated soil as in above, if self-leveling of fluidized treated soil is not sufficient, it is necessary to manage the sludge pipe mouth to move the position of the sludge pipe mouth. Come.

Further, when the interval between the structure and the sheet pile wall is small, the work efficiency is reduced because the backfilling operation is difficult. The present invention has been proposed in view of the problems of the prior art, and has as its object to provide a method for constructing an underground structure in an open-cutting method in which effective use of resources and work efficiency are improved. is there.

[0007]

According to the method for constructing an underground structure in the open-cutting method according to the present invention, in order to achieve the above object, a holding form for fluidized soil is installed on an excavated ground, Prior to the construction of the underground structure, backfilling with fluidized soil is performed, and after the fluidized soil is solidified, the holding form is removed, and the side surface formed by the solidified fluidized soil is removed. Is used as the outer formwork surface of an underground concrete structure, and the concrete and reinforcing bars and inner formwork of the same structure are installed below. In addition, fluidized treated soil is treated soil obtained by adding muddy water and solidifying material to soil generated at the site in an appropriate mixture, and has other fluidity, including those having fluidity and solidification strength according to the application, Includes all soil materials that do not require compaction and have a predetermined bearing capacity.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing the most preferred embodiments of the present invention. After constructing and excavating the improved ground 1 and constructing the retaining wall 2, the formwork 3 is installed. At this time, the waterproof sheet 4 is attached to the formwork surface on the earth retaining wall side as necessary. Next, retaining wall 2 and formwork 3
And the fluidized soil 5 is cast between them.

At this time, as a solidifying material for the fluidized treated soil 5,
When the speed of solidification of the fluidized soil 5 is accelerated by using a quick-setting solidified material, the earth pressure applied to the mold 3 from the fluidized soil 5 is reduced. As a result, the support work for holding down the same frame 3 is simplified, and the working efficiency is further improved. After the fluidized soil 5 has thus hardened, the mold 3 is removed. In the above-mentioned conventional method, the outer formwork of the underground structure was buried, but in this construction method, in addition to the function as the backfill material in the fluidized soil 5, the function as the outer formwork is provided. By using both, the conventional outer frame is not required.

In the figure, reference numeral 6 denotes discarded concrete. Next, a reinforcing bar for constructing an underground structure, an inner formwork, and the like are arranged in the formwork 3 and concrete is poured into the formwork 3 to construct an underground structure A. Thereafter, the above steps are repeated to complete the underground structure. As is clear from the above, the fluidized soil in this construction method is:
It functions as a backfill material, and after solidification, it functions as an outer formwork for underground structures.

[0011]

Conventionally, in the method of constructing an underground structure in the open-cutting method, the outer formwork was a buried formwork. However, in the present invention, a holding formwork for fluidized soil is provided on the excavated ground. Installation, backfilling with fluidized soil before construction of the underground structure, after solidification of the fluidized soil, remove the holding form and remove the side surface formed with the fluidized soil. By using it as the outer mold surface of the conventional method, the fluidized soil functions as an outer mold of the structure after solidification, in addition to the function as the backfill material, eliminating the need for form support. , Construction costs are reduced and workability is improved.

Further, according to the present invention, since the backfilling using the fluidized soil is performed, there is almost no possibility of settlement, and the fluidity of the fluidized soil is poor and self-leveling is impossible. However, since the backfilling is before the construction of the underground structure, the auxiliary work for maintaining the fluidized soil at the required level is easily performed, and the backfilling is before the construction of the structure. Even when the interval between the structure and the sheet pile wall is small, a sufficient work space for backfilling is ensured, and reliable work is facilitated and work efficiency is improved. According to the present invention, by using fluidized soil using generated soil, resources can be effectively used.

According to the present invention, when the waterproofing sheet is overlaid on the holding formwork, the waterproofing sheet and the fluidized soil are filled together with the backfill with the fluidized soil prior to the construction of the underground structure. Because it adheres, there is no fear of peeling of the waterproof sheet, and even if peeling occurs, it is before the construction of the underground structure,
In addition, since there is a sufficient working space as described above, the repair work is easy.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing an underground structure constructed by the method of the present invention.

FIG. 2 is a detailed view of a portion P of FIG.

FIG. 3 is a sectional view of a main part of a conventional method.

[Explanation of symbols]

 A Underground structure 1 Improved ground 2 Retaining wall 3 Formwork 4 Waterproof sheet 5 Fluidized soil 6 Discarded concrete

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI E02D 29/063 (72) Inventor Hironari Iino 4-6-15 Sendagaya, Shibuya-ku, Tokyo Inside Fujita Co., Ltd.

Claims (1)

[Claims] 1. A holding form for fluidized soil is set on an excavated ground, and backfilled with fluidized soil before construction of an underground structure, and after the fluidized soil is solidified, The holding form is removed, and the side surface formed by the solidified fluidized soil is used as the outer form surface of the underground concrete structure. Construction method of underground structure in open-cutting method characterized by the construction.