JP5596419B2 - Prestressed concrete structure - Google Patents

Description

  The present invention relates to a prestressed concrete structure, and more particularly to a prestressed concrete structure that can be used for a pressure vessel capable of excluding liquefied gas or high-pressure room temperature gas and realizing a large-scale capacity.

In recent years, global conferences that seek to solve global warming as a common global problem and efforts by various industries have become active. At the United Nations Climate Change Summit held in 2009, the Japanese Prime Minister The goal of reducing greenhouse gas emissions by 25% compared to 1990 is set by the world, which is highly evaluated worldwide. Here, “greenhouse gas” refers to carbon dioxide, methane, dinitrogen monoxide, chlorofluorocarbon alternative, and the like.

  The above-mentioned reduction of greenhouse gas emissions not only actually reduces greenhouse gas emissions themselves, but also prevents global warming by preventing the generated greenhouse gases from being released into the atmosphere. The above-mentioned concept of reduction also includes the fact that greenhouse gases generated by industrial activities and household activities are not released into the atmosphere.

Specific measures to prevent the release of greenhouse gases into the atmosphere include underground storage systems that inject CO ₂ into the underground reservoirs in land and sea as a supercritical state, and CO ₂ into the sea at a depth of 1000 m or more. A typical example is a marine storage system that releases, dissolves, and so on.

Regarding the means for transporting CO ₂ from the collection site to the storage site, when the transport distance is short, a method of transporting in a gas state using a pipeline can be applied, and when the transport distance is long, it is changed to liquefied CO _2. The tanker transport method can be applied. Then, the transported CO ₂ is changed to a supercritical fluid in the vicinity of the storage area, sent to the underground water-resistant layer in the land area or the sea area, and stored there.

As the demand for underground storage of greenhouse gases increases, the demand for large-capacity pressure vessels for storing the above-mentioned liquefied gas has also increased. The “large capacity” means a capacity scale of about 10,000 m ³ or more. The “pressure vessel” means a vessel having a maximum operating pressure of 0.05 Mpa or more, for example.

  With regard to this pressure vessel, most of the pressure vessels that have been constructed so far are made of steel, and therefore there was a limit to the increase in storage capacity due to manufacturing and legal issues (the reason for this will be described later). To do). On the other hand, although there are almost no pressure vessels made of concrete, all of the few achievements are LNG underground tanks, and the operating pressure of this LNG underground tank is 0.02 to 0.03 MPa, which is a very large internal pressure. It is not something to receive.

  One of the reasons why concrete pressure vessels have not been constructed so far is that when designing concrete pressure vessels that receive particularly high internal pressure, the side walls and bottom plates, which are the components, are the conventional PC tanks. Although a structure similar to (prestressed concrete tank) can be applied, it is difficult to design a roof that receives high upward pressure.

  There are a wide variety of conventional published technologies related to this PC tank. For example, the prestressed concrete structures disclosed in Patent Documents 1 and 2 can be cited as representatives thereof. It is no exaggeration to say that all of the roofs are dome-shaped for reasons such as having an advantageous structure against the weight of the roof. When a high gas pressure is applied from below the dome-shaped roof, excessive tensile force is dominant on the roof, and in the case of a concrete member, the load resistance performance of the roof itself is significantly reduced. In this case, the load-bearing performance of the joint between the roof and the side wall cannot be sufficiently secured, and the design for satisfying the load-bearing performance and rigidity is extremely difficult.

On the other hand, the results of CO ₂ storage tanks made of steel are mostly 1000 m ³ or less, and few exceed 1000 m ³ . If a large capacity of a steel CO ₂ storage tank is attempted, there is a certain limitation on the maximum capacity due to problems such as the difficulty of manufacturing thick steel plates and the difficulty of construction on site, as well as domestic regulations. The problem arises that it can be imposed.
In consideration of the above-mentioned various restrictions and capacity limits, in order to realize large-capacity storage of about 10,000 m ^3, which is the above-mentioned target storage capacity, the present inventors have made concrete capable of realizing this capacity scale. again focused on manufacturing tank, the conventional structure improved the structure of the roof very difficult to its durability and design added, the 10,000 m ³ grade large concrete container design and construction capable of realizing the present invention This is the idea of the prestressed concrete structure.

JP 2002-148380 A JP 2001-324586 A

  The prestressed concrete structure of the present invention has been made in view of the above-mentioned problems, and by adding a simple improvement to the structure of the roof, a roof having a load resistance performance against a high gas pressure acting from the inside can be realized. Accordingly, it is an object of the present invention to provide a prestressed concrete structure which can form a pressure vessel which has a load-bearing performance as a whole and can store a large volume.

In order to achieve the above object, a prestressed concrete structure according to the present invention includes at least a bottom plate, a cylindrical or substantially cylindrical side wall, and a roof rigidly connected to the side wall, and all of these components. In the prestressed concrete structure, the roof has a protruding curved shape on the bottom plate side, and a beam extending in a cylindrical or substantially cylindrical shape is formed at the upper end of the side wall, and the beam And the roof is rigidly connected, and the beam member is provided with a tension member extending in a cylindrical or substantially cylindrical shape, and one end of the roof is fixed to the beam member, and the cross section of the roof is inclined. Tensile material that penetrates and whose other end is fixed on the lower surface of the roof is arranged at intervals in the circumferential direction of the roof .

  The prestressed concrete structure of the present invention is at least a pressure vessel (pressure tank) composed of a bottom plate, a cylindrical or substantially cylindrical side wall, and a roof (ceiling) rigidly coupled to the upper end of the side wall. All of these components are formed from prestressed concrete. The bottom plate may be a direct foundation type supported directly on the ground or a pile foundation type supported by a pile or the like. Furthermore, not only the side wall and the roof, but also the bottom plate and the side wall may be rigidly coupled.

The prestressed concrete structure is intended for containment, while maintaining a vapor-liquid equilibrium state in the container, a part of the content is vaporized and liquefied gas that fills between the liquid surface and the roof or side wall of the container. General high-pressure room-temperature gas gases such as various liquefied greenhouse gases including liquefied CO ₂ gas, liquefied natural gas (LNG), liquefied petroleum gas (LPG), liquefied nitrogen, high-pressure room temperature natural gas, etc. Can be mentioned. Needless to say, the tank may be used for storing a liquid such as water that does not partially vaporize.

  The roof is made of prestressed concrete and is rigidly connected to the side wall, and the roof has a curved shape that protrudes toward the bottom plate, that is, a reverse dome shape opposite to that of the conventional structure. A roof having high rigidity and high load resistance against pressure can be realized.

  In other words, because the roof has a protruding shape with respect to the direction of gas pressure acting from below the roof, the compression force is excellent on the roof due to the arch effect due to the curved shape when pushed by the gas pressure, and excellent compression performance It is possible to effectively utilize the performance of the concrete, and the bending strength of the roof is also improved by this compression action. In addition, in the supplementary description, in the case of a dome-shaped roof having a conventional structure, the gas pressure acts upward from below the protruding roof, and the tensile force is dominant on the roof. Due to this, the bending strength was reduced. Furthermore, when trying to resist this excellent tensile force with tendons and reinforcing bars, these members often have to be over-packed, which is one factor in design difficulty. It was.

  According to the roof structure to which the prestressed concrete structure of the present invention is applied, the compressive force is dominant in the roof by the acting gas pressure, and since it is curved, an excessive bending moment is hardly generated based on the so-called arch effect. As a result, the amount of reinforcement, such as tendons and reinforcing bars, is significantly reduced as compared with the roof of the conventional structure, and its high rigidity and high load resistance are ensured.

  In addition, since the roof made of prestressed concrete and the upper end of the side wall are rigidly connected, the lifting of the roof with respect to the uplift due to the gas pressure from below the roof is suppressed. Therefore, as described above, an excessive cross-sectional force (particularly a bending moment) does not occur in the roof itself against the gas pressure, and as a result, an excessive cross-sectional force can also occur in the joint between the roof and the side wall. In addition to the absence, sufficient rigidity or load bearing performance against the uplift is also guaranteed.

  In addition, by applying an inverted dome-shaped roof, the compressive force is superior to the roof, and it is also possible to reduce the thickness of the roof by increasing the concrete specification (particularly the compression performance). Further, as described above, since the amount of tension material and the amount of reinforcing bars can be reduced as compared with the roof having the conventional structure, the construction cost can be significantly reduced.

  Here, as a more specific embodiment of the “curved curved shape on the bottom plate side”, the following plural types can be cited.

  One form thereof is a form in which the curved shape exhibits a part of an ellipsoid, and the other form is a form in which the curved shape exhibits a part of a spherical surface (including a hemispherical surface). is there.

  Here, “part of an ellipsoid” means not only a part of an ellipse when the roof is viewed in a longitudinal section, but also an ellipse when viewed from a plane, or a longitudinal section. It means that it is part of an ellipse and at the same time it is elliptical in plan.

  “Part of a spherical surface” means a hemispherical surface formed when a sphere is cut along a plane passing through its center point, but the smaller one that can be obtained when a sphere is cut along a plane that does not pass through its central angle. This means the curved surface shape of the cut sphere.

Further, in the prestressed concrete structure according to the present invention , a cylindrical or substantially cylindrical beam material, that is, a ring-shaped beam material is formed at the upper end of the side wall in order to increase the strength of the joint portion between the side wall and the roof. cage, that it said and the beams material roof is not bound Tsuyoshi.

Furthermore, in the prestressed concrete structure according to the present invention, the beam member is provided with a tension member extending in a cylindrical shape or substantially cylindrical shape, and one end of the roof member is fixed to the beam member, the penetrating obliquely, tendons other end is fixed on the lower surface of the roof that are spaced apart in the circumferential direction of the roof.

  Bending moment (bending moment generated at the roof end when viewed in a longitudinal section) and roof end, particularly at the roof end where the roof joins to the side wall A roof end structure that can resist the tensile force in the circumferential direction can be realized.

As can be understood from the above description, according to the prestressed concrete structure of the present invention, a so-called inverted dome-shaped roof is formed by inverting the so-called dome-shaped roof that has been adopted in the conventional structure. structural improvements, which are conventional and permit the design of prestressed concrete roof has been difficult design, has been to achieve the design and construction of a large capacity pressure vessel 10,000 m ³ primary or more of the scale It is.

It is the longitudinal cross-sectional view which showed one Embodiment of the pressure vessel concerning the prestressed concrete structure of this invention. It is the longitudinal cross-sectional view which showed the arrangement | positioning form of the tension material in the edge part of a roof, a side wall, and a bottom plate. It is a property diagram of the liquefied CO _2. It is the figure which showed the bending moment which arises in the roof and side wall of a pressure vessel by the gas pressure which acts on a roof. (A), (b) is the schematic diagram which each showed embodiment of the shape of the roof.

Embodiments of the present invention will be described below with reference to the drawings. In the prestressed concrete structure shown in the figure, the lower end of the side wall may be formed with a portion where the thickness of the member extending outwardly from the side wall is increased in a taper shape or multiple steps. Although contents contained in the pressure vessel shown is a liquefied CO ₂ gas which is a kind of greenhouse gases, in a state of being accommodated in a pressure vessel, it is partially due to the heat input from the outside or the like Of course, it may be liquefied gas of other greenhouse gases that vaporize and generate vaporized gas, liquefied natural gas (LNG), liquefied petroleum gas (LPG), liquefied nitrogen, high pressure room temperature gas gas, etc. It is. Further, in order to clarify the drawings, illustration of reinforcing bars arranged in each constituent member is omitted.

  FIG. 1 is a longitudinal sectional view showing an embodiment of a pressure vessel according to a prestressed concrete structure of the present invention, and FIG. 2 shows an arrangement form of tension members in an end portion, a side wall, and a bottom plate of a roof. It is the longitudinal cross-sectional view shown.

  The illustrated pressure vessel 10 includes a bottom plate 2 constructed on the ground, a cylindrical general portion 11 rigidly coupled to the bottom plate 2, and a ring-shaped beam member 12 formed at the upper end thereof. 1 and a roof 3 rigidly connected to the beam member 12, all of these constituent members are prestressed concrete members.

  In the pressure vessel 10 shown in the figure, the shape of the roof 3 has a curved shape that protrudes toward the bottom plate 2 when viewed in a longitudinal section, and more specifically, a shape of a part of a spherical surface. The so-called dome-shaped roof can be called an inverted dome-shaped roof.

Since the ring-shaped beam 12 is formed on the upper end of the side wall 11, it becomes easy to rigidly connect the beam 12 with the curved inverted dome-shaped roof 3 as shown in the figure, and the connection between the side wall 1 and the roof 3. the strength of the part Ru can be ensured.

  Further, in the illustrated example, the thickness of the roof 3 is changed at the center portion (thickness: t1) and the end portion (thickness: t2), and an end at which a relatively large cross-sectional force (bending moment, shearing force) can be generated. The thickness of the part is increased.

  Further, as shown by a one-dot chain line in FIG. 1, even if a roof 4 which is a non-structural member and prevents rainwater from collecting on the roof 3 is provided above the roof 3 which is a structural member. Good.

  In the side wall 1, a vertical tension member 51 (a PC steel bar, a PC steel wire, one end is fixed in the bottom plate 2 and the other end is fixed at the upper end of the beam member 12 is penetrated through the general portion 11. PC steel stranded wire) is disposed, and a tension member 52 extending in the circumferential direction is disposed on the outer periphery thereof, and prestress is introduced to these to impart a desired compressive force to the side wall 1. The bottom plate 2 is also provided with two upper and lower tension members 54 in the form of radial or cross beams, and prestress is introduced into them.

  On the other hand, the ring-shaped beam member 12 is also provided with a tension member 53 extending in the ring direction, that is, in the circumferential direction, and prestress is introduced thereto.

  The roof 3 has one end fixed to the beam member 12 and obliquely penetrates the cross section of the roof 3, and the other end fixed to the lower surface of the roof 3. ) Are arranged at intervals in the circumferential direction of the roof 3, and a desired compressive force is applied particularly to the end region of the roof 3 by introducing prestress into the roof 3. Note that the other end of the tension member 55 shown in the figure is fixed inside the roof 3, obliquely penetrates the roof 3, one end thereof is pulled out (X direction), and is fixed on the surface of the beam member 12. Yes.

In this pressure vessel 10, CO ₂ gas exhausted from various manufacturing factories, houses, etc. is compressed and liquefied, and liquefied CO ₂ L having a reduced volume is accommodated above the liquid level. The CO ₂ gas G that is partially vaporized is filled.

Here, regarding the liquefied CO ₂ accommodated in the container, a property diagram that changes depending on the temperature and pressure is shown in FIG. As shown in the figure, in general, CO ₂ is liquefied under temperature and pressure conditions above its triple point B (approximately −50 ° C., approximately 0.7 MPa) to become liquefied CO ₂ , and its critical point A (approximately 30 ° C. If the pressure exceeds about 7 MPa, it becomes a supercritical state and has characteristics of both gas and liquid.

The maximum operating pressure in the pressure vessel 10 is 0.05 MPa or more. More specifically, the properties are adjusted so that the liquefied CO ₂ storage conditions are 0.7 ± 0.1 MPa, −50 ° C., and the specific gravity is in the range of about 1.138 to 1.154. In addition, a cold insulating material (not shown) is disposed on the inner wall surface of the pressure vessel 10, but a part of the liquefied CO ₂ is vaporized due to heat input from the outside that enters a considerable amount, and CO ₂ is above the liquid surface. The gas will be full. This gas pressure (pressure P in FIGS. 1 and 4) acts on the roof 3 as an internal pressure, and simultaneously acts on the side wall 1 and the bottom slab 2 as an overload added to the hydraulic pressure.

Here, FIG. 4 shows the bending moment in the axial direction generated in the roof 3 and other components, particularly the side wall 1 when an internal pressure by CO ₂ gas acts on the pressure vessel 10. For easy understanding, the axis of the roof 3 is L1, the axis of the side wall 1 is L2, and the axis of the bottom plate 2 is L3.

  In the pressure vessel 10 shown in the figure, since the roof 3 and the side wall 1 and the side wall 1 and the bottom plate 2 are both rigidly connected to each other, an upward tension bending moment (positive in the figure) is formed near the end of the roof 3. Bending moment) occurs, and this is reversed to generate a lower tension bending moment (negative bending moment in the figure) at the end, and an inner tension bending moment (negative bending moment in the figure) at the upper end of the side wall 1. ) Occurs, and reversal is repeated in the middle of the side wall, and the bending moment of the inner tension can be similarly generated at the lower end.

  Therefore, the roof 3 has a comparative example that can occur at the end thereof. In order to resist a large positive bending moment, the tension material 55 is arranged at the end in the oblique direction as shown in the figure above the roof section. An arrangement form is applied.

In addition, although illustration is omitted, in practice, the hydrostatic pressure due to liquefied CO ₂ and the CO ₂ gas pressure that is the load on the side wall 1 act on the side wall 1, and the head pressure due to liquefied CO ₂ and the CO ₂ gas that is the load on top thereof. The pressure acts on the bottom plate 2 and the bending moment generated in each component member is calculated in consideration of these acting forces and the gas pressure acting on the roof 3, and the cross-section design and tension material design that can resist this are calculated. Will be done.

  In any case, since the roof 3 constituting the pressure vessel 10 has a curved shape protruding toward the bottom plate 2, the roof 3 has a compressive force due to the so-called arch effect. The bending strength of is improved.

  Regarding the curved shape of the roof, FIGS. 5a and 5b show embodiments other than the roof 3 shown in FIG.

  The roof 3A shown in FIG. 5a has a shape of a part of a horizontally long elliptical shape when viewed in a longitudinal section. The roof 3A may have a circular shape in plan view, or may have a horizontally long elliptical shape as in the longitudinal section.

  On the other hand, the roof 3B shown in FIG. 5b has a hemispherical shape when viewed in a longitudinal section, and is a roof shape having a larger degree of curvature than a part of the spherical surface shown in FIG.

  In the pressure vessel 10 of the present invention shown in the figure, even if there are variations in the shape of the roof, all of them have a protruding curved shape on the bottom plate side as a common configuration, An arch effect can be expected, and the compressive force is excellent inside the gas pressure acting from below, and the bending strength is improved by the compressive force.

  And the structure is based on a very simple structural improvement by simply inverting the conventional so-called dome shape, and there is no increase in the construction cost during the construction of the roof, but rather the compression force inside the roof. It is also possible to reduce the amount of tension material and the amount of reinforcing bars to be disposed inside by excellence.

Thus, while allowing reduced construction costs, by having a prestressed concrete roof with a high flexural strength against internal gas pressure, the container becomes ^tertiary or more capacity scale of the pressure vessel 10,000m Therefore, it is suitable as a large-capacity pressure vessel for storing greenhouse gases whose demand is increasing.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

DESCRIPTION OF SYMBOLS 1 ... Side wall, 11 ... General part, 12 ... Beam material, 2 ... Bottom plate, 3,3A, 3B ... Roof, 51, 52, 53, 54 ... Tension material, 55 ... Tension material of roof edge part, 10 ... Prestressed concrete structure (pressure vessel), L ... liquefied _{CO 2,} G ... _CO 2 gas

Claims (5)

In a prestressed concrete structure comprising at least a bottom plate, a cylindrical or substantially cylindrical side wall, and a roof rigidly coupled to the side wall, and all of these components are made of prestressed concrete,
The roof has a protruding curve on the bottom plate side ,
A beam extending in a cylindrical or substantially cylindrical shape is formed at the upper end of the side wall, and the beam and the roof are rigidly coupled,
The beam material is provided with a tension material extending in a cylindrical shape or a substantially cylindrical shape,
One end of the roof is fixed to the beam member, and a tension member that penetrates the cross section of the roof obliquely and the other end is fixed to the lower surface of the roof is arranged at intervals in the circumferential direction of the roof. prestressed concrete structures are.   The prestressed concrete structure according to claim 1, wherein the curved shape is a part of an ellipsoid.   The prestressed concrete structure according to claim 1, wherein the curved shape is a part of a spherical surface. The prestressed concrete structure according to claim 1 , wherein the curved shape is a hemispherical surface. The prestressed concrete structure is subjected to accommodation of liquefied gas, and the liquefied gas causes an upward internal pressure to act on the roof by the vaporized gas partially vaporized in the accommodated state. The prestressed concrete structure in any one of 1-4 .

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