JP6569103B2 - Basic structure of tower structure - Google Patents

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 to the windward are installed. 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 the tower for wind turbines , it is necessary to extend the top to the highest position as much as possible and support heavy objects on the top

  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, there is a possibility that sufficient durability cannot be provided as a base structure of a tower-like structure whose top is extended to a high position in the sky like a tower for a windmill. In particular, it can be said that the rupture mechanism in the tower for wind power generation cannot secure sufficient proof strength only by the 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, for example, in the case where the reinforcing bars are overcrowded when constructing the foundation structure according to Patent Document 5, the same effect is obtained. It is desired to simplify the construction by another method that can be expected.

  Therefore, the present invention is a foundation structure in which pre-stress is introduced and concrete is driven using an unbonded anchor, and the construction is simplified to prevent harmful cracks occurring in the concrete, and the falling moment It aims at providing the foundation structure of the tower-like structure which can fully resist.

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 a tower structure where at least a tipping moment, horizontal force, etc. are applied, a prestressed unbond anchor that fixes the column base of the tower structure is arranged in a direction parallel to the unbond anchor. It was a vertical line, and is joined to each of the longitudinal muscle, and hoop forming a circumference arranged at appropriate intervals in the longitudinal direction of said longitudinal muscle, a direction crossing the Unbonded anchor, the concrete foundation portion It consists of a portion of the outer peripheral edge and passing by arranging the PC steel wire subjected to other portions, the unbonded anchor and vertical stripe, hoop, by implanting concrete to the PC steel wire, the PC steel wire Ri is characterized in that by Prestressing is formed a concrete foundation.

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 bolts and the anchor ring at the lower end where pre-stress is introduced is firmly integrated to transmit the load to the anchor ring. In this case, compressive stress is generated in the vertical direction of the concrete, while tensile stress 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, a further vertical compressive stress is added to the compressive stress by 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 tensile stresses, to resist tensile Rukoto force is offset by the hoop and the crosses on the anchor bolt arranged with prestressing force introduced by PC steel wire.

  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 basic structure of the tower-like structure according to the invention of claim 3 is characterized in that the PC steel wires are radially arranged in the diameter direction of the circumference where the unbonded anchors are arranged.

  When the unbond anchor is arranged on the circumference, the PC steel wire is arranged in the diameter direction of the arc. It can equally resist the tipping moment in any direction applied to the tower structure.

  In addition, the foundation structure of the tower-like structure according to the invention of claim 4 is formed such that the concrete foundation portion has a footing portion and a pedestal portion raised from the footing portion, and the vertical bars are the footing portion. 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 PC steel wire to be disposed. Concrete is driven into the unbonded anchor, the vertical bars, the hoop bars, and the PC steel wire 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.

  In addition, the basic structure of the tower-like structure according to the invention of claim 5 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 tower for wind turbines. As the structure of the foundation to support the chimney and various tower etc. There are various types, a both considering overturning moments and horizontal forces structures, as in the case of the wind turbine, cyclic loading and rotating machine It is not designed to resist fatigue loads due to. The basic structure according to the present invention, by arranging the PC steel wire, since it is possible to resist the tensile stress of the concrete foundation portion acting in a direction intersecting with Unbonded anchor, towers for wind turbines and the like repeatedly load is applied It will be suitable for the basis of.

  According to the basic structure of the tower-like structure according to the present invention, even after the prestress is introduced, the vertical bars, the PC steel wires, and the hoops arranged with respect to the unbond anchor to the stress acting on the concrete. When the prestress is introduced due to the resistance of the streaks, cracks in the concrete due to the acting load due to the external force thereafter and the fatigue load due to repetition can be suppressed, and the 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 basic structure of the tower-like structure according to the invention of claim 3, the PC steel wire can be efficiently arranged and reliably pulled in any direction crossing the longitudinal direction of the unbonded anchor. Can resist stress.

  Moreover, according to the foundation structure of the tower-like structure which concerns on invention of Claim 4, 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 the construction can be facilitated.

  Further, according to the basic structure of the tower-like structure according to the invention of claim 5, even if 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. Further, outside the outer vertical bars 7a, an annular outer hoop line 9a extends along the circumference centered on the column cross-sectional center C of the tower- like structure 1, and inside the inner vertical bars 7b, the inner hoop line 9b. Are joined to the longitudinal bars 7 respectively.

  As shown in FIGS. 1 and 2, a plurality of PC steel wires 8 are arranged in the radial direction of the arc in which the unbond anchor 5 is arranged to form a pedestal portion 3b in which the unbond anchor 5 is arranged. Prestress is introduced into the concrete to be used. As shown in FIG. 1, the PC steel wires 8 are arranged at a plurality of locations in the vertical direction at appropriate intervals. The fixing tool 8a of the PC steel wire 8 is exposed on the peripheral wall surface of the pedestal portion 3b.

  Concrete is driven into the unbonded anchor 5 and the longitudinal bars 7a and 7b, the hoop bars 9a and 9b, and the PC steel wire 8 that are stretched over the base plate 4 and the anchor plate 6 in a state where pre-stress is introduced. A pedestal 3b is formed. The PC steel wire 8 is arranged in a sheath (not shown), and after the laid concrete is cured, it is tensioned and fixed by the fixing tool 8a to introduce prestress. Further, the pedestal portion 3b only needs to be formed to have an outer diameter dimension capable of arranging the PC steel wire 8.

  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 PC steel wire 8 and the hoop bars 9a and 9b arranged so as to intersect with the longitudinal direction of the unbond anchor 5 and the longitudinal bars 7a and 7b arranged parallel to the longitudinal direction of the unbond anchor 5 are used. And resist each. Therefore, the occurrence of cracks in the concrete is suppressed as much as possible, and breakage is prevented.

  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 prestress introduced by the PC steel wire 8 resists 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 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.

  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 8 PC steel wire
8a Fixing tool
9a Outer hoop muscle
9b medial hoop muscle

Claims (5)

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-like structure and introducing prestress,
Longitudinal bars arranged in a direction parallel to the unbond anchor;
A hoop line that is joined to each of the vertical bars and forms a circumference arranged at appropriate intervals in the longitudinal direction of the vertical bars,
It is a direction that intersects the unbond anchor, and consists of a PC steel wire that is arranged to span from the outer peripheral part of the concrete foundation part to the other part ,
Concrete tower is formed by injecting concrete into the unbonded anchor and longitudinal bars, hoop bars, PC steel wire, and introducing prestress with the PC steel wire to form a concrete foundation. Foundation structure.   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.   The foundation structure of the tower-like structure according to claim 2, wherein the PC steel wires are radially arranged in a diameter direction of a circumference where the unbond anchors are arranged. 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 any one of claims 1 to 3, wherein the vertical bars are made to reach the footing part.   The tower structure according to any one of claims 1 to 4, wherein the tower structure is a column base for wind power generation.

Images