JPH073826A - Construction method of dome-like roof in underground tank - Google Patents

Abstract

PURPOSE:To reduce an initial amount of prestress to be introduced in the case a dome-like roof of an underground tank is constructed. CONSTITUTION:After an earth retaining wall 1 is constructed in the ground G, a dome-like roof 2 is constructed and is temporarily borne on an opening edge 1a facing to the ground of the earth retaining wall 1, and then, a primary prestress is introduced to the peripheral surface 2a of the roof 2 along the circumferential direction. After that, a bottom slab 4 and a part 5a of the side wall continued to the bottom slab 4 are constructed in an excavated hole 3 formed inside the earth retaining wall 1 to make a space 6 between part 5a of the side wall and the roof 2, and a secondary prestress is introduced to the peripheral surface 2a of the roof 2. In the case the primary prestress is introduced, horizontal thrust force occurring in the roof 2 is reduced by excavation load W of the ground G, and in the case the secondary prestress is introduced, prestress force is not propagated to the side wall, so that an initial amount of prestress is reduced as a whole.

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 a dome type roof in a concrete underground tank in which a low temperature liquefied gas or the like is stored.

[0002]

2. Description of the Related Art Conventionally, in the case of constructing a tank of this type underground, first, in a drill hole formed by excavating the ground,
A skeleton consisting of a concrete bottom slab and a concrete cylindrical side wall standing upright from the peripheral portion of the bottom slab is constructed.

After the skeleton is completed, a concrete dome type roof covering the opening of the skeleton is constructed on the opening edge of the side wall to connect the two, and at the same time, in the outer peripheral portion of the roof, a plurality of ridges are formed along the outer peripheral portion. A PC steel material is inserted and wound, and these PC steel materials are tensioned to maintain the state, so-called prestress is introduced. This prestressing force prevents the roof from spreading due to the horizontal thrust force generated by its own weight and vertical load, and serves to support the construction state.

[0004]

By the way, in the above method, since prestress is introduced into the outer peripheral portion of the roof while being connected to (the side wall of) the body, the prestressing force propagates to the side wall. . Therefore, the amount of prestress introduced must be the amount of resistance to the horizontal thrust force plus the amount of propagation to the sidewall. That is, the prestressing force is not limited to introducing only the horizontal thrust force of the roof, and in addition to this,
Since it is necessary to introduce a loss component that propagates to the side wall, there is a problem that prestress introduction is not efficient.
There is also a demand for the amount of prestress introduced to be lower than the amount capable of resisting the horizontal thrust force of the roof.

The present invention has been made in view of the above circumstances, and the amount of prestress to be introduced when constructing a dome type roof for an underground tank can be reduced as compared with the prior art, and an efficient prestress can be achieved. It is intended to provide a method of constructing a dome type roof in an underground tank that can be introduced.

[0006]

The present invention has been made in order to achieve the above-mentioned object, and is a bottomed cylindrical body composed of a concrete side wall and a bottom slab, which is constructed in the ground. In constructing an underground tank consisting of a concrete disk-shaped dome roof covering the opening of this frame, after constructing a cylindrical earth retaining wall in the ground, on the opening edge of this earth retaining wall facing the ground, The roof is constructed and temporarily supported, and then the first portion along the circumferential direction is provided on the outer peripheral portion of the roof.
Next, the prestress is introduced, and then the ground inside the earth retaining wall is excavated, and then the bottom slab and a part of the side wall following the bottom slab are built in the drill hole to form a part of the side wall. A space is provided between the roof and the roof, and then a secondary prestress is introduced into the outer peripheral portion of the roof.

[0007]

According to the method for constructing a dome type roof in an underground tank according to the present invention, the amount of introduction of the first prestress is such that the earth retaining wall is constructed by the excavating load consisting of earth pressure and water pressure around the earth retaining wall. The horizontal thrust force generated on the roof is reduced, so that the required amount can be reduced. Furthermore, the second
When introducing the next prestress, since there is a space between the side wall and the roof, the prestressing force does not propagate to the side wall. All you need to do is reach your strength. As a result, the total prestress introduction amount can be reduced as compared with the conventional case, and the prestress can be introduced efficiently.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in order of steps with reference to the drawings.

[Step 1] As shown in FIG. 1, first, in the ground G, the earth retaining wall 1 corresponding to the side wall forming the skeleton of the underground tank to be constructed is constructed in a cylindrical shape.

[Step 2] Opening edge 1a at the top of the earth retaining wall 1
To the ground, the opening edge 1a covers the opening of the earth retaining wall 1 to construct a concrete dome type roof 2 by casting concrete, and the roof 2 is temporarily attached to the earth retaining wall 1. Support.

[Step 3] Inside the outer peripheral portion 2a of the roof 2, a plurality of PC steel materials (not shown) are inserted along the outer peripheral portion 2a and wound, and the PC steel materials are tensioned and held in that state. By doing so, the first prestress is introduced. The introduction amount of the first prestress is a required amount required at the time of construction, and is about half of the finally introduced amount.

[Step 4] The ground G inside the earth retaining wall 1 is excavated.

[Step 5] As shown in FIG. 2, a bottom slab 4 which constitutes the skeleton of the underground tank is constructed at the bottom of the excavation hole 3, and then the skeleton of the underground tank is also provided on the outer peripheral portion of the bottom slab 4. Part of the side wall 5a that is constructed by standing up and constructed, between the part 5a of the side wall and the outer peripheral portion 2a of the roof 2,
The space 6 is left open.

[Step 6] The PC steel material wound around the outer peripheral portion 2a of the roof 2 is further tensioned to introduce a second prestress into the outer peripheral portion 2a. The amount of the secondary prestress introduced is the amount finally required.

The roof 2 is now constructed. Next, in order to finally construct the underground tank, concrete is poured into the space 6 to complete the side wall 5, and the side wall 5 and the roof 2 are connected. FIG. 3 shows a skeleton 7 consisting of a bottom slab 4 and side walls 5, and a completed underground tank 8 consisting of a roof 2.

In the method of constructing the dome type roof 2 of the present embodiment, as the ground G is excavated in [Step 4], as shown in FIG. 1, the ground G around the earth retaining wall 1 is removed. An excavating load W consisting of earth pressure and water pressure acts toward the inside, and this excavating load W passes through the earth retaining wall 1
It acts on the roof 2 as a force for canceling the horizontal thrust force generated by the own weight and the vertical load of the roof 2.

The amount of prestress introduced in [Step 3] is about half of the final amount introduced, but for example, the amount of prestress required for the roof 2 at the stage of [Step 4] for forming the excavation hole 3 is increased. If the amount of stress introduced is 50% of the final required amount and the force for canceling the horizontal thrust force due to the excavating load W supplements the prestress force by 10%, [Step 3]
The introduction amount of prestress in the above is substantially 40%.

As a result, the amount of secondary prestress to be introduced in [Step 6] is 50% of the finally required amount. Therefore, the total amount of prestress to be introduced into the roof 2 is the finally required amount minus the amount compensated by the excavation load W, which is 90% in this case.

Conventionally, it has been necessary to introduce the prestress introduced into the roof into an amount sufficient to resist the horizontal thrust force, and also to introduce the loss that propagates to the side wall.
In the present embodiment, the introduction amount is lower than the introduction amount that can resist the horizontal thrust force of the roof. Therefore, the equipment required to introduce prestress to the roof (P
It is possible to reduce the burden on C steel material, jacks for tension, etc.,
Prestress can be introduced efficiently.

[0020]

As described above, according to the method for constructing a dome type roof in an underground tank of the present invention, a bottomed cylindrical frame body constructed of concrete side walls and a bottom slab is constructed, In constructing an underground tank consisting of a concrete disk-shaped dome roof covering the opening of this frame, after constructing a cylindrical earth retaining wall in the ground, on the opening edge of this earth retaining wall facing the ground, The roof is constructed and temporarily supported, then the primary prestress is introduced to the outer peripheral portion of the roof along the circumferential direction, then the ground inside the earth retaining wall is excavated, and then the excavation is performed. In the hole, the bottom slab and a part of the side wall subsequent to the bottom slab are constructed to leave a space between the part of the side wall and the roof, and then a second portion is formed on the outer periphery of the roof. Characterized by introducing next prestress Therefore, when introducing the first pre-stress, the horizontal thrust force generated on the roof by the excavation load of the ground is reduced, and when introducing the second pre-stress, the pre-stress force does not propagate to the side wall. As a whole, the amount of introduction of prestress is reduced, and it is possible to effectively introduce prestress.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a first half of steps in a method according to an embodiment of the present invention.

FIG. 2 is a side sectional view showing the latter half.

FIG. 3 is a side sectional view of the underground tank in a completed state.

[Explanation of symbols]

 1 Earth retaining wall 1a Opening edge 2 Dome type roof 2a Peripheral part 3 Excavation hole 4 Bottom plate 5 Side wall 5a Part of side wall 6 Space 7 Body 8 Tank G Ground W Excavation load

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location E04H 7/18 302 9023-2E (71) Applicant 000206211 Taisei Corporation Shinjuku-ku, Shinjuku-ku, Tokyo No. 25-1 (71) Applicant 000174943 Mitsui Construction Co., Ltd. 3-10-1 Iwamoto-cho, Chiyoda-ku, Tokyo (72) Inventor Masafumi Nakano 3-23-3 Kamuijojo, Kita-ku, Tokyo (72) Invention Author Yoshinori Kawamura 3-34, Akatsukashinmachi, Itabashi-ku, Tokyo Urban Life Yuri-no-Dori East Building 1 Room 305 (72) Inventor Ken Shirasuna 2-3 Kandaji-cho, Chiyoda-ku, Tokyo Obayashi Corporation (72) ) Inventor Satoru Amano 2-3 Kandaji-cho, Chiyoda-ku, Tokyo Obayashi Corporation (72) Incorporator Masamichi Yasunaga 1-2-7 Moto-Akasaka, Minato-ku, Tokyo Kashima Ken Incorporated Co., Ltd. (72) Inventor Takeuchi et al., Moto Akasaka 1-3-8, Minato-ku, Tokyo Kashima Construction Co., Ltd. Tokyo Branch (72) Inventor Masanobu Kuroda 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Junsei Sejima 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Ken Ken Nakano 1-25-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo Taisei Construction Co., Ltd. (72) Inventor Minoru Nada 1-25-1 Nishishinjuku, Shinjuku-ku, Tokyo Taisei Construction Co., Ltd. (72) Inventor Masatoshi Kato 3-10-1 Iwamotocho, Chiyoda-ku, Tokyo Mitsui Construction Co., Ltd. (72) Inventor Takemasa Yamada 3-10-1 Iwamotocho, Chiyoda-ku, Tokyo Mitsui Construction Co., Ltd.

Claims (1)

[Claims] 1. An underground tank is constructed which is constructed in the ground and has a bottomed cylindrical skeleton composed of a concrete side wall and a bottom slab, and a concrete disk-shaped dome type roof covering the opening of the skeleton. After constructing a cylindrical earth retaining wall in the ground, the roof is constructed and temporarily supported at the opening edge of the earth retaining wall facing the ground, and then the outer peripheral portion of the roof is circumferentially supported. Along with the introduction of the first prestress, then excavating the ground inside the earth retaining wall, and then constructing the bottom slab and a part of the side wall following the bottom slab in this drilling hole, A method for constructing a dome type roof in an underground tank, characterized in that a space is left between a portion of a side wall and the roof, and then a second prestress is introduced into an outer peripheral portion of the roof.