JPH0748950A - Structure of buried storage tank roof - Google Patents

Abstract

(57) [Abstract] [Purpose] It is an object of the present invention to provide a structure of a buried storage tank roof that can easily and reliably improve the waterproof performance of a concrete roof. [Structure] A roof 3 that is buried underground and closes the upper opening of a cylindrical storage tank with a bottom for storing low-temperature liquefied gas, a roof main body 4 that closes the upper opening of the storage tank 2, and an upper surface of the roof main body 4 , A heat insulating material 5 provided so as to cover the upper surface, the heat insulating material 5 blocks heat transfer between the roof body 4 and the ground surface, and the roof body 4 is always kept at 0 degrees Celsius or less, Even if the groundwater passes through the heat insulating material 5, it immediately freezes, so that the waterproof performance as a roof can be easily and surely improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a buried tank roof structure for storing low temperature liquefied gas and the like.

[0002]

2. Description of the Related Art In a conventional low temperature liquefied gas underground storage tank, since the roof (made of steel) is exposed above the ground, a hot water heater or It is equipped with heating equipment such as a brine heater. However, in the above-mentioned low temperature liquefied gas underground storage tank, the roof is exposed to the ground, so that the roof is exposed to sunlight, and since the members that make up the roof are made of steel, the heat transfer coefficient is large, so The amount of heat input to the air increases and the amount of boil-off gas increases. Therefore,
In order to reduce the amount of generated Boilhoff gas, a low temperature liquefied gas underground storage tank is provided in which the roof of the storage tank is made of concrete and completely buried underground.

[0003]

However, when the roof is completely buried underground as described above, there are the following problems.

It is well known that frozen soil has waterproofness and airtightness. Therefore, if stable frozen soil can be generated on roof concrete irrespective of external temperature changes, etc., the water stop performance of the roof concrete itself will be further improved. However, there was a problem that the thickness of the frozen soil was not constant due to the change of the outside temperature, and even if the frozen soil was generated in the winter, it was melted in the summer.

When vegetation is applied to the ground surface where the roof is buried, it is necessary to control the area where the soil covering the roof freezes. Depending on the thickness of the soil covered on the roof,
If the minimum required thickness is secured, the freezing area will also fluctuate greatly due to fluctuations in the outside temperature. To control this variation, it is conceivable to install a hot water heater network in the cover soil on the roof, as with conventional sidewalls. However, in this case, the temperature is different between the vicinity of the tube and the tubes, and the zero-degree line shows a wavy distribution. Therefore, in order to satisfy both the control of the freezing area of the soil cover and the improvement of the waterproof property of the roof, it is necessary to take measures such as narrowing the pipe arrangement interval and changing the temperature of hot water depending on the season. It is difficult to implement these measures from the economical aspect or the aspect of maintenance.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a structure of a buried storage tank roof which can easily and surely improve the waterproofness of a concrete roof.

[0007]

In order to achieve the above object, the structure of a buried storage tank roof according to claim 1 of the present invention is a bottomed cylindrical storage tank which is buried underground to store low temperature liquefied gas and the like. The roof that closes the upper opening includes a roof main body that closes the upper opening of the storage tank, and a heat insulating material that is provided on the upper surface of the roof main body so as to cover the upper surface.

Further, according to the structure of the buried storage tank roof of claim 2, the roof for closing the upper opening of the bottomed cylindrical storage tank which is buried underground and stores the low temperature liquefied gas and the like is closed for the upper opening of the storage tank. A roof main body, a frozen soil layer laid on the upper surface of the roof main body so as to cover the upper surface, and a heat insulating material provided on the upper surface of the frozen soil layer so as to cover the upper surface. It is a thing.

[0009]

In the structure of the buried storage tank roof according to claim 1 of the present invention, the heat insulating material blocks heat transfer between the roof main body and the ground surface, so that the roof main body is not affected by the change in the outside temperature. By constantly maintaining the temperature below zero degrees Celsius, even if groundwater passes through the heat insulating material, it immediately freezes, so that the waterproofness of the roof can be easily and reliably improved.

Further, in the structure of the buried storage tank roof according to claim 2, the heat transfer between the ground surface and the frozen soil layer is blocked by the heat insulating material so that the frozen soil layer can be changed in the outside air temperature. Regardless, it always keeps the frozen state to improve the water blocking ability easily and surely, and also to secure the non-frozen area between the heat insulating material and the ground surface.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the structure of a buried storage tank roof according to the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment. In this figure, reference numeral 1 is an underground tank for storing low temperature liquefied gas. The underground tank 1 is composed of a storage tank 2 buried underground and a roof 3 that closes an upper opening of the storage tank 2. The storage tank 2 includes a bottom slab 2a formed of cast-in-place concrete or the like,
It comprises a cylindrical side wall 2b made of reinforced concrete or the like arranged on the bottom slab 2a or on the outer periphery of the bottom slab 2a. Has been done.

The roof 3 is mainly composed of a roof body 4 formed on the upper edge of the side wall 2b and a heat insulating material 5 provided on the upper surface of the roof body 4 so as to cover the upper surface. . The roof body 4 is made of a concrete material such as reinforced concrete or prestressed concrete, and an airtight holding material and a cold insulating material 10 are applied to the inner surface thereof.

The heat insulating material 5 reduces the amount of heat transfer between the roof body 4 and the ground surface, and is made of, for example, styrofoam, heat insulating concrete or the like having a low water absorption and a heat insulating property. . When a heat insulating material having high water absorption is used, the outer peripheral portion of the heat insulating material is coated to prevent deterioration of the heat insulating performance due to water absorption. Also,
The thickness of the heat insulating material 5 depends on the temperature of the stored liquid, changes in the outside air temperature,
It is determined by the thermal conductivity of the heat insulating material.

In the structure of the buried storage tank roof having the above structure, the heat transfer amount between the roof body 4 and the ground surface is reduced by the heat insulating material 5 provided on the upper surface of the roof body 4, so that Almost no temperature difference occurs between the inner surface side and the front surface side. Therefore, since the roof body 4 is always kept at zero degrees Celsius or less, even if groundwater passes through the heat insulating material, it immediately freezes, and the waterproofness of the roof 3 can be improved easily and surely.

Further, since the amount of heat input into the storage tank 2 is reduced by providing the heat insulating material 5, the amount of boil-off gas can be reduced. Further, by providing the lightweight heat insulating material 5 having a certain thickness on the upper surface of the roof body 4, it is possible to reduce the load of soil covering on the roof 3.

FIG. 2 shows a second embodiment, in which reference numeral 6 indicates a roof. The roof 6 includes a roof body 7 that closes the upper opening of the storage tank 2, a frozen soil layer 8 laid on the upper surface of the roof body 7 so as to cover the upper surface, and an upper surface of the frozen soil layer 8. , And a heat insulating material 9 provided so as to cover the upper surface. Like the heat insulating material 5, the heat insulating material 9 is also made of a material such as styrofoam or heat insulating concrete that has low water absorption and has heat insulating properties.

The frozen soil layer 8 is formed by laying cover soil on the upper surface of the roof main body 7 and is frozen through the roof main body 7 by the cold heat of the low temperature liquefied gas stored in the storage tank 2. . The frozen soil layer 8 has a heat insulating material 9 provided on the upper surface thereof so that heat transfer to and from the ground surface is blocked and the frozen soil layer 8 is always maintained in a frozen state regardless of the outside temperature.

In the structure of the buried storage tank roof having the above-mentioned structure, the heat transfer between the ground surface and the frozen soil layer 8 is blocked by the heat insulating material 9, so that the frozen soil layer is always maintained regardless of the change of the outside temperature. It is maintained in a frozen state, and the waterproofness of the roof 6 can be easily and surely improved, and a non-frozen region can be secured between the heat insulating material 9 and the ground surface for vegetation or the like. .

By the way, in an underground concrete roof type LNG underground storage tank, when the soil cover thickness is 2.0 m and the roof thickness (roof body thickness) is 2.5 m, the heat insulating material 9 is used.
Without the provision, the entire roof could not be kept below 0 degrees Celsius in the summer, and the non-freezing area could be secured only up to about 80 cm in the winter when the atmospheric temperature in the storage tank was low. On the other hand, a 10 cm thick styrene foam insulation 9
By laying, a non-freezing area can be secured up to a depth of 120 cm even in winter, and even if the atmosphere temperature in the storage tank is high, 1
Throughout the year I was able to keep the entire roof below zero degrees Celsius. That is, it was found that the above-mentioned structure of the buried storage tank roof has a function of controlling a sufficient freezing area and a function of improving the water stop performance. Further, in the structure of the buried storage tank roof, once the heat insulating material 9 is laid, the above functions can be exhibited without the need for maintenance and management, and the economy and the practicability are excellent.

[0020]

As described above, according to the structure of the buried storage tank roof of the first aspect of the present invention, the heat insulation between the roof body and the ground surface is provided by the heat insulating material provided on the upper surface of the roof body. Since the amount of transmission is reduced, the roof body is always kept below 0 degrees Celsius, and even if groundwater passes through the heat insulating material, it immediately freezes, so that the waterproofness of the roof can be easily and reliably improved. A non-frozen region can be secured between the heat insulating material and the ground surface to apply vegetation or the like.

Further, according to the structure of the buried storage tank roof of the second aspect, the heat transfer between the ground surface and the frozen soil layer is reduced by the heat insulating material, so that the frozen soil layer changes in the outside temperature. Regardless of the fact that it is always frozen, it can easily and reliably improve the waterproofness of the roof, and it is also possible to secure a non-frozen area between the heat insulating material and the ground surface for vegetation etc. it can.

[Brief description of drawings]

FIG. 1 is a side sectional view of an underground tank, showing a first embodiment of the structure of the buried storage tank roof of the present invention.

FIG. 2 shows a second embodiment of the structure of the buried storage tank roof of the present invention, and is a side sectional view of a main part of an underground tank.

[Explanation of symbols]

 1 Underground tank 2 Storage tank 3,6 Roof 4,7 Roof body 5,9 Insulation material 8 Frozen soil layer 10 Airtight holding material and cold insulation material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (71) Applicant 000206211 1-25-1, Nishishinjuku, Shinjuku-ku, Tokyo Taisei Corporation (71) Applicant 000174943 Mitsui Construction Co., Ltd. 3--10-1, Iwamoto-cho, Chiyoda-ku, Tokyo No. (72) Koji Minegishi, Koji Minegishi 1-2-2, Ichikawa-shi, Chiba Sunny House Minami Gyotoku B-213 (72) Inventor Masafumi Nakano 3-3, Kamijijojo 3-chome, Kita-ku, Tokyo (72) Inventor Ken Shirasuna 2-3-3 Kandajimachi, Chiyoda-ku, Tokyo Within Obayashi Corporation (72) Inventor Hirofumi Yamashita 2-3, Kandajimachi, Chiyoda-ku, Tokyo Obayashi Corporation (72) Inventor Masamichi Yasunaga Minato-ku, Tokyo Moto Akasaka 1-27 Kashima Construction Co., Ltd. (72) Inventor Takeuchi et al. Moto Akasaka 1-3-8 Kashima Construction Co., Ltd. Tokyo Branch (72) Akito Kuroda Masanobu Kuroda 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Atsushi Sejima 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Shoichi Watanabe 1-25-1 Nishishinjuku, Shinjuku-ku, Tokyo Within Taisei Corporation (72) Inventor Masayuki Moriya Within 1-25-1 Nishishinjuku, Shinjuku-ku, Tokyo Inside Taisei Corporation (72) Masatoshi Kato Tokyo 3-10-1 Iwamotocho, Chiyoda-ku Mitsui Construction Co., Ltd. (72) Inventor Muneki Watanabe 3-10-1 Iwamotocho, Chiyoda-ku, Tokyo Mitsui Construction Co., Ltd.

Claims (2)

[Claims] 1. A roof structure which is buried underground and closes an upper opening of a bottomed cylindrical storage tank for storing low-temperature liquefied gas and the like, wherein the roof has a roof main body which closes the upper opening of the storage tank. A structure of a buried storage tank roof, comprising: an insulating material provided on an upper surface of the roof body so as to cover the upper surface. 2. A roof structure which is buried underground and closes an upper opening of a bottomed cylindrical storage tank for storing low-temperature liquefied gas and the like, wherein the roof has a roof main body which closes the upper opening of the storage tank. And a frozen soil layer laid on the upper surface of the roof main body so as to cover the upper surface, and a heat insulating material provided on the upper surface of the frozen soil layer so as to cover the upper surface. The structure of the buried storage tank roof.