JP2017125360A - Foundation structure of towering structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foundation structure of a towering structure such as a brace and a tower, which prevents concrete from cracking in the foundation structure having a column base part that is fixed by using an unbonded anchor to introduce prestress.SOLUTION: An unbonded anchor 5 is placed across circular base plate 4 and anchor plate 6 concentric with a towering structure 1 and introduces prestress. Vertical reinforcements 7a, 7b are disposed in parallel with the longer direction of the unbonded anchor. An X-direction horizontal reinforcement 8x and a Y-direction horizontal reinforcement 8y, which are perpendicular to each other in plan view, are disposed so as to intersect with the unbonded anchor 5 and the vertical reinforcements 7a, 7b. Lower ends of the vertical reinforcements 7a, 7b are extended to a footing portion 3a of a foundation 3. External diameter of a pedestal part 3b of the concrete installed after the reinforcements are arranged is long enough to dispose the X-direction horizontal reinforcement 8x and the Y-direction horizontal reinforcement 8y.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a foundation structure of a tower-like structure constructed up to a high position in the sky such as a pillar, a tower, a monument, etc. constructed on the ground, and particularly relates to a foundation structure using an unbonded anchor for introducing prestress. .

  There are various tower-like structures constructed on the ground, such as various towers, monuments, and chimneys. One of them is a tower for wind turbines, which is a column of wind turbines for wind power generation. At the top of the tower, there are a plurality of propeller blades (blades), and a generator that generates electricity by rotating the windmill, and a nacelle that becomes a heavy object such as a rotating mechanism that aligns the direction of the windmill with the windward Yes. Further, in order to stably increase the power generation efficiency, it is necessary to receive a stable wind, and it is desirable to place the top at a high position as much as possible. That is, in a windmill tower, it is necessary to extend a top part to a high position as much as possible, and to support a heavy article on the top part.

  In the tower-like structure, a large horizontal load is received by the wind in the sky. For this reason, a bending moment acts as a tipping moment on the foundation of the tower-like structure. In particular, in the tower for wind turbines, in addition to the horizontal load, a complex load is repeatedly applied by rotating the blades of the wind turbine, changing the direction of the wind turbine by the rotating mechanism, and the combination of these various loads. This may cause the windmill tower to fall over. In Japan, the overturning moment due to the seismic load is large, so a foundation structure that can handle earthquakes in addition to wind loads is desired.

  For example, a ground anchor combined pile method disclosed in Patent Document 1, a wind power generation tower disclosed in Patent Document 2, and Patent Document 3 disclosed as a proposal for a basic structure of a high-rise building or a tower-shaped structure. There is an anchor frame of the windmill tower. Further, in Patent Document 4, a column base hardware joined to the lower end of a steel column as a steel column base capable of securing anchor bolt fixing strength without increasing the size of the basic concrete is disclosed as basic concrete. A steel column base is disclosed which is fixed on foundation concrete with anchor bolts and nuts embedded therein.

  In addition, the applicant of the present application is a foundation structure of a tower-like structure such as a column or a tower, and in the foundation structure having a column base portion fixed by using an unbonded anchor that introduces prestress, the occurrence of cracks in the concrete is caused. The basic structure of the tower-like structure which suppresses as much as possible was proposed (refer patent document 5). The basic structure disclosed in Patent Document 5 is a tower-like structure in which the top portion extends to a high position in the sky, and at least an overturning moment, a horizontal force, and the like act by an external force acting on the top portion and the column base. In the basic structure of an object, the column base of the tower-like structure is fixed, an unbonded anchor for introducing prestress, a vertical bar arranged in a direction parallel to the unbonded anchor, and the vertical bar A hoop bar having a circumference arranged at an appropriate interval in the longitudinal direction of the vertical bar, and radial horizontal bars arranged in a direction intersecting the unbond anchor and the vertical bar, the unbond anchor and the vertical bar The concrete foundation is formed by driving concrete into the hoop bars and radial horizontal bars around the circumference.

  Further, in Non-Patent Document 1, a method for designing a columnar reinforcing bar of a rising portion (pedestal) of a footing foundation is described. Regarding the design of an anchor bolt, a connecting member joined to a bolt lower end with a nut or the like. Examine whether the stress caused by (anchoring) satisfies the concrete tolerance and the tolerance of the anchoring member itself, and whether the anchor bolt surface adheres to the concrete It is supposed to be.

  Further, in Non-Patent Document 2, the design is made with a smaller allowable pulling force determined by the cone-shaped fracture of the headed anchor bolt and a smaller allowable value of the anchor bolt member itself.

Japanese Patent Publication No. 5-59219 JP 2002-122066 A JP 2004-278400 A Japanese Patent Laid-Open No. 5-25832 Japanese Patent No. 4242445

Chimney structure design and construction guidelines (Japan Architecture Center) Various structural design guidelines (Architectural Institute of Japan)

  The support structure by the pile method disclosed in Patent Document 1 is mainly a building, which resists the buoyancy generated in the building by receiving a tipping moment due to a horizontal force caused by wind, earthquake, etc. Thus, when a complicated overturning moment occurs, reliability may not be ensured. Further, in the wind power generation tower disclosed in Patent Document 2, a tower body formed by stacking hollow cylinders and a prestressed concrete reinforcing member having a T-shaped cross section along the outer periphery on the base side of the tower body. The reinforcing member is coupled and fixed to the foundation and the tower body. In addition, an anchor frame disclosed in Patent Document 3 includes a pair of upper and lower ring-shaped anchor plates, a plurality of connection members that connect the pair of upper and lower anchor plates at a predetermined interval, and the connection between the connection members. A plurality of anchor bolts and a plurality of struts connected to the lower surface of the lower anchor plate for positioning the pair of upper and lower anchor plates at a predetermined height on the foundation, the connecting member and the struts Is made of steel pipe.

  In the basic structure disclosed in Patent Document 2 and Patent Document 3, a pedestal that is a base pedestal protruding from the center of the base member is formed, and a tower is fixed to the pedestal. And anchor bolts and struts. However, since the driven concrete and the anchor bolt are joined with adhesive force, if the falling moment is loaded and this adhesion breaks, the concrete will crack, and if the allowable stress of the concrete is exceeded, There is a risk of damaging the concrete. For this reason, it is desirable that the foundation has a structure that does not have adhesion between the anchor bolt and the concrete, and has a structure using an unbonded anchor that reduces the load on the concrete by changing the load transmission mechanism.

  Moreover, in the steel column base disclosed in Patent Document 4, the tensile force of the anchor bolt is transmitted to the reinforcing bar by satisfying the dimensional condition according to the present invention for the load generated in the horizontal direction in the concrete, and the cone It is said that the size of the foundation can be reduced by preventing the destruction of the state. However, the failure mechanism of concrete foundations is not limited to cone-like failure. Especially, in the tower for wind power generation, as mentioned above, heavy objects may be installed at the top of the tower. It is thought that the destruction mechanism works. Therefore, in the invention described in Patent Document 4, as the foundation structure of the tower-like structure in which the top portion extends to a high position in the sky like a windmill tower, there is a possibility that sufficient durability cannot be provided. In particular, it can be said that the rupture mechanism in a tower for wind power generation cannot secure sufficient strength only by cone-shaped fracture, which is a problem in the steel column base described in Patent Document 4.

  In addition, as disclosed in Non-Patent Document 5 and Non-Patent Document 6, the conventional tower-like structure foundation structure includes anchor bolts attached to concrete with reference to the pointers and the like, and nuts or the like at the lower end thereof. The connecting member (anchor ring) to be joined together is arranged at the rising part (pedestal) of the footing foundation, and is designed on the basis of resisting the overturning moment received from the upper structure by the columnar structure.

  The support structure of a tower-like structure (tower) typified by a chimney is a structure in which a pedestal that is a base pedestal protruding from the center of the base member is formed, and the tower is fixed to this pedestal. The fixing portion is composed of the anchor bolt and the connecting member (anchor ring) in the placed concrete. In addition, it is designed on the assumption that the concrete and the anchor bolt are bonded and joined. When a falling moment is loaded, a tensile force is transmitted through the concrete to the vertical reinforcing bars arranged beside the anchor bolt.

  On the other hand, for a wind turbine tower or the like, the natural period of the superstructure can be determined by fixing the legs. When it is desired to achieve this complete fixation or a state close to this, it is conceivable to use an unbonded anchor and to have a structure in which a tension force (prestress) is applied to the anchor bolt after the concrete is driven. In addition, a rotating machine such as a windmill may prestress the bolt for the purpose of preventing fatigue failure of the foundation bolt that is constantly subjected to load fluctuations.

  When prestress is applied using an unbonded anchor, tensile load acts on the concrete around the unbonded anchor in the vertical direction below the anchoring part (anchor ring) of the unbonded anchor and in the crossing direction (horizontal direction) of the unbonded anchor. Therefore, a stress state different from anchor bolts expected to adhere to concrete that does not apply prestress will occur, and if there is a lack of reinforcing bars necessary for prestressing, immediately after prestressing Even under normal load on the tower structure, cracks occur in the concrete, and when the cracks progress, the concrete may break along the unbonded anchors. The structure that resists the tipping moment of the leg by this structure transmits a tensile force through the concrete to the vertical reinforcing bars arranged in parallel to the anchor bolts, and the radial horizontal bars have a tipping moment. Resists horizontal tensile force generated on the compression side.

  Therefore, as disclosed in Patent Document 5, even when pre-stress is introduced using an unbonded anchor, the foundation does not cause harmful cracks in the concrete and can sufficiently resist the overturning moment. The above-mentioned problem was solved by using a tower-like structure base structure in consideration of the shape and the arrangement of reinforcing bars.

  The present invention relates to the improvement of the foundation structure disclosed in Patent Document 5, and in the same manner as the foundation structure, using an unbonded anchor, a foundation structure in which prestress is introduced and concrete is driven into the construction. Therefore, an object of the present invention is to provide a foundation structure of a tower structure that can prevent harmful cracks that occur in concrete and can sufficiently resist a falling moment.

  As a technical means for achieving the above object, the foundation structure of the tower-like structure according to the present invention is such that the top part extends to a high position in the sky, and the external force acting on the top part and the column base part, In the foundation structure of the tower structure where at least a tipping moment, horizontal force, etc. are applied, an unbonded anchor that introduces prestress for fixing the column base part of the tower structure and a direction parallel to the unbonded anchor are arranged. A vertical reinforcing bar, and a horizontal reinforcing bar arranged in a direction intersecting the unbonded anchor and the vertical reinforcing bar in a direction orthogonal to each other in plan view. A concrete foundation is formed by driving

  In the state where the tower-like structure is supported by the unbonded anchor introduced with the prestress, there is no adhesion between the unbonded anchor and the concrete, so that the load is not transmitted. However, the concrete surrounded by the unbonded anchor bolt introduced with the prestress and the anchor ring at the lower end is firmly integrated to transmit the load to the unbonded anchor bolt. In this case, compressive stress is generated in the vertical direction of the concrete, while a tensile force is generated simultaneously to try to expand the concrete in the horizontal direction intersecting with the compressive stress. Further, as a reaction force to the foundation due to the external force acting on the top, further compressive stress is added to the compressive stress due to the prestress introduction in the compression side concrete portion due to the overturning moment. Similarly, the tensile stress in the horizontal direction is further increased. These horizontal stresses are resisted by making these tensile stresses intersect with the anchor bolts and orthogonal to each other.

  Moreover, the foundation structure of the tower-shaped structure which concerns on invention of Claim 2 has arrange | positioned the said unbonded anchor on the leg lower periphery of the tower-shaped structure which should be supported, It is characterized by the above-mentioned.

  In order to arrange unbond anchors efficiently, the structure is arranged on the circumference centered on the column cross-section center position of the tower-like structure, and a pair of unbond anchors are arranged in parallel in the radial direction of the arc. It is arranged. In this case, it is preferable to arrange the vertical stripes at a position sandwiching the unbonded anchor.

  Moreover, the foundation structure of the tower-shaped structure which concerns on invention of Claim 3 forms the said concrete foundation part in the shape which has a footing part and the base part raised from this footing part, The said vertical streak is said footing part It is characterized by having reached.

  It does not have a pedestal on the top surface of the footing part, and may be formed on a flat surface or an inclined surface that can drain rainwater, or a shape in which a pedestal part is formed on the top of the footing part. It does not matter if it is. It is sufficient that the pedestal is formed in a size that allows the horizontal rebar to be arranged. Concrete is driven into the unbonded anchor, vertical bars, and horizontal bars to form the pedestal. In this case, the lower end of the vertical bar extends to the footing part and is joined to the reinforcing bar arranged in the footing part.

  Moreover, the basic structure of the tower-like structure according to the invention of claim 4 is characterized in that the tower-like structure is a column base for wind power generation.

  The foundation structure according to the present invention is particularly suitable for supporting the column base portion of the wind turbine tower. There are various types of basic structures that support chimneys and various towers, etc., all of which take into account the overturning moment and horizontal force. It is not designed to resist fatigue loads due to. In the foundation structure according to the present invention, by arranging the horizontal reinforcing bar, it is possible to resist the tensile stress of the concrete foundation portion acting in the direction intersecting with the unbonded anchor, and therefore for wind turbine towers where repeated loads and the like act. It will be suitable for the foundation.

  According to the foundation structure of the tower-like structure according to the present invention, even after the pre-stress is introduced, the vertical bars and the horizontal reinforcing bars arranged with respect to the unbond anchor are applied to the stress acting on the concrete. Resisting, when pre-stress is introduced, cracks in the concrete due to acting load due to subsequent external force and fatigue load due to repetition can be suppressed, and breakage can be prevented.

  Further, according to the basic structure of the tower-like structure according to the invention of claim 2, it is possible to reliably resist the load acting in any direction regardless of the direction due to the external force acting on the tower-like structure. .

  Moreover, according to the foundation structure of the tower-like structure which concerns on invention of Claim 3, the quantity of the concrete to drive in becomes the minimum and construction cost can be reduced. In addition, when the upper surface is a flat surface or an inclined surface without forming the pedestal portion, the shape of the foundation is simplified, so that construction can be facilitated.

  Moreover, according to the basic structure of the tower-like structure according to the invention of claim 4, even when a load from a rotating machine or the like is applied, it is not collapsed, and particularly for wind power generation where a complicated load is applied. It is suitable to be used for the foundation that supports the column base.

It is a rough sectional view of the foundation provided with the structure concerning this invention. It is sectional drawing cut | disconnected along the AA line in FIG. It is a schematic perspective view explaining the arrangement | positioning state of the unbonded anchor of the foundation structure which concerns on this invention. It is a figure explaining the outline of distribution of the load which acts on the circumference of the unbond anchor which introduced prestress.

  Hereinafter, the basic structure of the tower-like structure according to the present invention will be specifically described based on the illustrated preferred embodiment.

  FIG. 1 shows an outline of a foundation provided with a structure according to the present invention, and shows a state in which a tower-like structure 1 such as a column base for wind power generation is supported. A foundation 3 is disposed on a pile 2 driven into the ground of the construction site of the tower-like structure 1. In this embodiment, the foundation 3 is formed in a shape including a footing portion 3a and a pedestal portion 3b.

  As shown in FIG. 3, the tower-like structure 1 is fixed to an annular base plate 4 via unbonded anchors 5. The unbonded anchor 5 is stretched over the base plate 4 and the anchor plate 6 so that prestress is introduced. The base plate 4 and the anchor plate 6 are formed in a circular shape as shown in FIGS. 2 and 3, and a pair of unbonded anchors 5 are arranged in the radial direction of the circular shape, and these pairs are arranged on the circumference. Are arranged along. Note that the center of the base plate 4 or the like is substantially coincident with the column cross-sectional center C of the tower-like structure 1. Longitudinal stripes 7 a and 7 b are arranged in parallel with the unbond anchor 5. The lower ends of the vertical bars 7a and 7b reach the footing part 3a of the foundation 3, and are joined to the bar arrangement 3c arranged in the footing part 3a. The vertical bars 7a and 7b are provided with an outer vertical bar 7a on the outer side and an inner vertical bar 7b on the inner side with the anchor bolt 5 in between.

  As shown in FIG. 2, X-direction horizontal bars 8x and Y-direction horizontal bars 8y, which are horizontal reinforcing bars, are arranged in a state perpendicular to each other in plan view. A plurality of these X-direction horizontal streaks 8a and Y-direction horizontal streaks 8y are arranged, respectively, and are in the relationship of the positions of twists arranged at positions shifted in the height direction.

  Concrete is driven into the unbonded anchor 5 and the vertical bars 7a and 7b, the X-direction horizontal bars 8x, and the Y-direction horizontal bars 8y that are stretched over the base plate 4 and the anchor plate 6 in a state where pre-stress is introduced, and the footing portion 3a. And the pedestal 3b. The pedestal portion 3b only needs to have an outer diameter that allows the X-direction horizontal stripes 8x and the Y-direction horizontal stripes 8y to be arranged.

  In the foundation structure configured as described above, for example, the concrete around the unbonded anchor 5 into which prestress is introduced in order to fix the tower for the windmill, the longitudinal direction of the unbonded anchor 5 as shown by the broken line in FIG. A tensile load acts on the direction intersecting with the longitudinal direction. With respect to these tensile loads, the X-direction horizontal bars 8x and Y-direction horizontal bars 8y arranged so as to intersect with the longitudinal direction of the unbond anchor 5 and the vertical bars 7a arranged parallel to the longitudinal direction of the unbond anchor 5 are used. , 7b resist each other. Therefore, the occurrence of cracks in the concrete is suppressed as much as possible, and breakage is prevented.

  In addition, so-called fiber concrete in which short fibers such as synthetic fibers and steel fibers are mixed into the concrete to be poured can be used, and the occurrence of cracks can be further suppressed against the tensile force applied to the concrete.

  Also, when a horizontal load received by wind or earthquake acts as a tipping moment, a load similar to the above is applied, and in addition, a horizontal tensile force is applied to the concrete foundation on the compression side due to the tipping moment. . The X-direction horizontal stripes 8x and Y-direction horizontal stripes 8y resist the horizontal tensile stress generated in the surrounding concrete, and the occurrence of cracks in the concrete is suppressed as much as possible, and the breakage is prevented.

  In the embodiment described above, the base plate 4 or the like is described as a circular shape, and the unbond anchor 5 is arranged on the circumference. However, according to the cross-sectional shape of the tower-like structure 1, it is arranged in another shape. You can also. Further, one pair of unbonded anchors 5 is arranged in the radial direction, but one or three or more unbonded anchors may be arranged.

  Further, in the above-described embodiment, the basic structure suitable for the tower of wind power generation has been described. However, the basic structure is not limited to this, and the basic structure of the tower-like structure extended to a high position in the sky such as a monument or a chimney. It can also be used.

  According to the tower structure according to the present invention, the column base is fixed by using an unbonded anchor introduced with pre-stress, and resists the tensile stress that occurs when the tipping moment is transmitted to the concrete. It becomes a basic structure suitable for a tower for a wind turbine in which a large horizontal load repeatedly acts, can be prevented from collapsing as much as possible, and can contribute to extending the useful life of the tower-like structure.

1 tower-like structure 2 pile 3 foundation
3a Footing part
3b Base 4 Base plate 5 Unbonded anchor 6 Anchor plate
7a, 7b longitudinal bars
8x horizontal stripe in X direction
8y horizontal stripe in Y direction

Claims (4)

In the basic structure of the tower-like structure in which the top part extends to a high position in the sky and at least a falling moment and a horizontal force act on the top part and the column base part by an external force,
An unbond anchor for fixing the column base portion of the tower structure, for introducing prestress,
Longitudinal bars arranged in a direction parallel to the unbond anchor;
It is a direction intersecting the unbond anchor and the longitudinal bars, and is composed of horizontal reinforcing bars arranged in directions orthogonal to each other in plan view,
A foundation structure of a tower-like structure, wherein concrete is formed by driving concrete into the unbond anchors, vertical bars and horizontal bars.   The foundation structure of a tower-like structure according to claim 1, wherein the unbond anchor is arranged on a circumference below the legs of the tower-like structure to be supported. Forming the concrete foundation part into a shape having a footing part and a pedestal part raised from the footing part;
The foundation structure of the tower-like structure according to claim 1, wherein the vertical bars reach the footing portion.   The foundation structure of the tower-like structure according to any one of claims 1 to 3, wherein the tower-like structure is a column base for wind power generation.

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