JP3831737B2 - Steel tower basic structure - Google Patents

Description

  The present invention relates to a foundation structure of a steel tower for supporting a main pedestal of the steel tower.

  In particular, as a foundation structure of a power transmission tower in a mountainous area, when the support layer is relatively shallow, an inverted T-shaped foundation 50 shown in FIG. 24 is adopted, and the support layer is deep or the pulling strength is large. The main foundation 51 shown in FIG. 25 is mainly adopted.

  On the other hand, the foundation of the power transmission tower is more strongly affected by the wire tension, the typhoon, the seasonal wind and the like than the influence of the weight of the tower and the weight of the wire. As a result, the overturning moment becomes larger than the total compressive load due to other factors, so the compressive load acts on the leeward steel tower legs, while the compressive load (indentation force) acts on the leeward steel tower legs. About 70% of the lifting load (pullout force) is applied. Further, a bending moment is applied by a couple of forces due to the pushing force and the pulling force, and a horizontal force is applied.

  Therefore, in the foundation supporting the steel tower legs, even when the inverted T-shaped foundation 50 is adopted, a required earth covering thickness is required to resist the pulling force and horizontal force, and the diameter is 4 to 5 m, the depth. The excavation of about 5 to 10 m was performed, and the foundation was constructed using the floored surface as a construction base surface (see Patent Document 1 below).

On the other hand, in the case of the deep foundation 51, the scale is generally about 2.5 to 3 m in diameter and about 6 to 20 m in depth. However, in mountainous areas, it is often difficult to carry in heavy machinery due to topographic conditions. The excavation is done exclusively by manual drilling. In this manual excavation, an operator enters a narrow space, and the ground plate is excavated deeply by reverse winding while sequentially arranging liner plates on the wall surface of the vertical hole for retaining the earth (see Patent Document 2 below) reference).
Japanese Patent Laid-Open No. 53-11606 JP-A-7-23511

  As described above, in the case of steel tower foundations, horizontal force acts along with a large pulling force due to the influence of wind loads, so the foundation shape becomes relatively large, and the amount of excavation and earth retaining for foundation construction There is a tendency for the concrete amount of the support and foundation to increase.

  Also, if the bedrock is near the ground surface and it is difficult to excavate with heavy excavators, blasting must be used at the same time, and assembling of the retaining support must be done mainly by manpower, which is a heavy workload At the same time, there was a problem that the process was prolonged.

  On the other hand, in the foundation (footing) for supporting the steel tower legs, as shown in FIG. 26, when the footing becomes too shallow in the fixing portion of the main pedestal 52 and the footing 53, the base of the main pedestal 52 is centered. Cone-like shear cracks 54 may be generated and the fixing portion may be destroyed. Further, as shown in FIG. 27, when the pile body 55 is too close to the outer edge of the footing 53, split crack-like shear cracks 56, 56... is there. Further, when the footing is too thin, there is a problem that a cone-shaped shear crack 54 may be generated around the pile body 55 as shown in FIG.

  Therefore, if the footing 53 is designed so as to have sufficient strength against these pushing force, pulling force, bending moment, and horizontal force so as not to cause cracks, the footing scale becomes large and the footing becomes large. As a result, the amount of excavation increased and the amount of concrete placement increased, causing a lot of time and labor for the construction.

  Therefore, the main problem of the present invention is to reduce the labor load by enabling the reduction of the structural scale of the foundation and the simplification of construction, and the basic structure of the steel tower that can reduce the construction cost and the process. Will be offered.

In order to solve the above-mentioned problem, the present invention according to claim 1 is a foundation structure for supporting each main pedestal of a steel tower, wherein the foundation structure is in a direction substantially coincident with the direction of the main pedestal. Along one or more main piles provided in the ground, one or more sub piles provided in the ground along the plane direction connecting the foundation and the tower center in plan view, the main pile and the sub And a combined structure in which the base of the main pillar is fixed,
The joint structure is a structure formed by placing concrete in a steel pipe, the top of the main pile is joined to the lower surface side of the joint structure, and the top of the sub-pile is joined to the side. basic structure of the tower, characterized in that is is provided.

  In the present invention according to claim 1, the surface direction connecting the foundation and the center of the tower in plan view with one or more main piles provided in the ground along a direction substantially coinciding with the direction of the main pedestal 1 or a plurality of sub-piles provided in the ground along with the main pile and the sub-pile, and a basic structure consisting of three elements including a combined structure in which the base of the main pedestal is fixed It is what.

  Truss towers such as power transmission towers have a certain directivity in the load acting on the foundation (1) Hongo, Tanabe, Matsuo, "Allowable displacement of large transmission tower foundation in plain Review of Transmission Lines, Transmission Line Construction Materials, Technical Committee on Transmission Line Construction, November 2000, Vol. 47, p. 111-128, (2) Hongo, Tanabe, Matsuo, “Displacement of foundations of transmission towers in mountainous areas "Reasonable design method that takes into account", Electric Power Engineering, Japan Electric Power Engineering Technology Association, November 1999, No.284 p95-99, etc., and measurement and analysis. According to this result, the load acting on the foundation acts on a line connecting the center of the foundation and the center of the tower in a plane regardless of the direction of the wind load. This is because the direction of the main pedestal of the power transmission tower is all toward the center of the tower, and the bottom node frame is loosely restrained by the diagonal abdomen and is not a frame like a ramen structure. The horizontal force due to the axial force of the pedestal is dominant, and the larger the steel tower, the longer the abdomen, so the distortion of the abdomen is small and the stress does not tend to change drastically with some deformation of the foundation. This is considered to be due to such reasons.

  Therefore, by orienting the main pile and sub-pile along the direction connecting the center of the foundation and the center of the tower, it becomes possible to effectively resist the large pushing force and pulling force acting on the foundation.

  By providing the main pile along a direction in which the direction substantially coincides with the direction of the main pedestal column, the horizontal load due to the horizontal component of the axial force acting from the main pedestal column is eliminated, and the bending moment applied to the main pile is It is possible to reduce the shearing force. Note that one or more main piles are arranged, and the arrangement is a target arrangement with respect to the central axis of the steel tower.

  The secondary pile is provided along the plane direction connecting the foundation and the center of the tower in plan view, thereby taking part of the bending and shearing force generated in the foundation and reducing the bending and shearing force generated in the main pile. To do.

  Although it will be described in detail in the examples described later, it is possible to control the displacement direction by controlling the displacement, in particular, compared to a single pile, by using a combined pile structure in which the main pile and the secondary pile are combined. Various effects can be obtained such that the pulling strength can be greatly improved, and the change in the supporting strength is small even if the load direction is changed.

  From the above, by using a combined pile structure that combines the main pile and the sub-pile, it is possible to obtain a foundation structure with sufficient strength even though it is compact, and to reduce the size of the foundation and simplify the construction. As a result, the labor load can be reduced, and the construction cost and the process can be shortened.

In the invention described in claim 1 , the joint structure is a structure formed by placing concrete in a steel pipe (hereinafter also referred to as a concrete structure).

  Conventionally, the design of the anchoring part of the tower main pedestal was reinforced by the anchoring strength based on the allowable tensile stress and allowable shear stress of the concrete, but it is predicted that it will not be sufficient from safety detection. In some cases, in order to further improve the fixing strength, reinforcement based on empirical rules has been made, and thus over-reinforcement was sometimes made. In view of this situation, the present applicant has conducted extensive studies on efficient foundation design and reinforcement. As a result, as disclosed in JP 2000-345571 A, continuous stress acts on the main pedestal. Then, horizontal cracks and vertical cracks (split cracks) occur in the concrete. And in the case of the support pressure fixing method, it is greatly affected by the occurrence of the above-mentioned split crack, and when this split crack occurs, the knowledge that even if one of them reaches the foundation surface, it will break down. I came to get. In addition, the inventors of the present application dramatically improve the fixing strength by reinforcing the direction perpendicular to the split crack, that is, the circumferential direction of the main pedestal with a steel pipe, and improving the restraint of the concrete to suppress split fracture. What we can do is gained from a dozen model experiment and numerical analysis.

  Accordingly, if it is possible to suppress the split crack as much as possible, the fixing strength can be improved and the joint portion (foundation portion) can be reduced, so that a concrete structure having the above structure is formed. The tops of a plurality of pile bodies placed inside are joined, a fixing member is provided at the lower part of the main tower pillar, and the main pillar part provided with the fixing member is embedded in the concrete structure The basic structure is the same.

  As a result, by constraining the concrete on which the steel pipe is placed from the outside (periphery), split cracks can be prevented, and the anchoring strength of the concrete structure can be greatly improved. Since it can be arranged close to the wall surface, the scale of the concrete structure can be greatly reduced. In addition, since the scale of the concrete structure can be reduced, the construction time can be shortened, the excavation amount can be reduced, and the concrete placement amount can be reduced. Furthermore, by using a combined structure composed of the steel pipe and concrete, it is possible to install a plurality of piles in addition to one, and easily absorb construction errors of the main pile and sub-pile. It becomes possible.

According to a second aspect of the present invention, the steel pipe has a steel tower foundation structure according to the first aspect , wherein the steel pipe has a plurality of vertical ribs on the inner wall surface, which are fixed along the circumferential direction. Provided.

In the invention according to the second aspect , the steel pipe has a structure in which a rib for ribs fixed on the inner wall surface along the circumferential direction is provided in a plurality of stages in the vertical direction. By providing the anti-blur rib on the inner wall of the steel pipe, a sufficient adhesion force can be secured with the concrete to be placed.

As the present invention according to claim 3 , there is provided a steel tower foundation structure according to any one of claims 1 and 2 , wherein an angle formed by the main pile and the sub-pile is not less than 30 degrees and not more than 90 degrees.

In this invention of the said Claim 3, angle (theta) which the said main pile and a subpile make is 30 to 90 degree | times, Preferably it is 40 to 60 degree | times. When the angle θ formed by the main pile and the sub-pile is less than 30 degrees, a desired effect as a group pile cannot be obtained. Moreover, when the angle θ between the main pile and the sub-pile exceeds 90 degrees, construction such as concrete placement becomes difficult, and it is not necessary to set the intersection angle θ to 90 degrees or more in the actual ground.

As the present invention according to claim 4 , there is provided the foundation structure of the steel tower according to any one of claims 1 to 3 , wherein the main pile is a reinforced concrete structure and is a pile body having a diameter of 250 to 600 mm.

In the present invention according to the fourth aspect , the main pile is a reinforced concrete pile body having a diameter of 250 to 600 mm. As the main pile, it is desirable to use a cast-in-place reinforced concrete pile that has high compressive strength and pull-out strength, and can be simply installed and loaded. When the diameter of the pile is 600 mm or less, even if the ground is a rock layer, a rotary impact type down-the-hole hammer (trade name) can be used, and even when excavating rocks, construction can be performed at high speed. It is. As concrete to be used, it is desirable to use high-fluidity concrete kneaded on site.

As the present invention according to claim 5 , the sub-pile is an anchor pile or a reinforced concrete structure. A steel tower foundation structure according to any one of claims 1 to 4 is provided.

In the invention described in claim 5 , the auxiliary pile is an anchor pile or a reinforced concrete pile body. The secondary pile is a secondary pile that reinforces the main pile, and there is no particular limitation on the type of pile, but if the compressive strength is sufficient only by the main pile, it may be an anchor pile that requires simple construction However, in the case of design conditions that require the required compressive strength and pull-out strength, it is desirable to use a reinforced concrete pile body having a large compression strength and pull-out strength. In addition, the said anchor pile is a structure which functions with respect to extraction force, and does not function with pushing force. Also in the case of the reinforced concrete structure, it is desirable to use high-fluidity concrete that is kneaded on site so that the concrete can be turned to every corner, corrosion resistance can be expected, and durability is improved.

As the present invention according to claim 6, wherein Fukukui the substructure of tower according to any one of claims 1-5 having at least 20% or more of the pulling strength of the pull-out strength of the main pile is provided.

In the invention described in claim 6 , the sub-pile is a pile body having a pulling strength of at least 20% of the pulling strength of the main pile. Since the secondary pile has a pulling strength of 20% or more of the main pile, even after the pulling resistance force of the main pile exceeds the maximum value, the sub pile will share the decrease in the strength of the main pile. It is possible to take a fracture form with high toughness.

  As described above in detail, according to the present invention, by using a combined pile structure in which a main pile and a sub-pile are combined, it is possible to provide a foundation structure that is compact but has sufficient proof strength, a reduction in the structural scale of the foundation, Simplification is possible, the labor load can be reduced, construction costs can be reduced, processes can be shortened, and the like.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[First embodiment]
As shown in FIGS. 1 and 2, the tower foundation structure according to the present invention includes one or a plurality of main piles 1 provided in the ground along a direction substantially coinciding with the direction S of the main pedestal 4; One or more sub-piles 2 provided in the ground along the surface direction connecting the foundation and the tower center P in plan view, the main pile 1 and the sub-pile 2 are combined, and the main pedestal 4 And a bonded structure 3 to which the base portion is fixed.

In more detail below,
As the coupling structure 3, for example, a structure composed of a thick steel pipe 6 having a diameter of about 1000 to 5000 mm and a thickness of about 20 to 30 mm, and concrete 7 placed inside the steel pipe 6 is preferably used. The

  On the inner wall surface of the steel pipe 6, shift prevention ribs 5, 5... Fixed in the circumferential direction are provided in a plurality of stages in the vertical direction. The misalignment prevention ribs 5, 5,... May have any cross-sectional shape as long as it is a projection shape that can reliably prevent slippage with the concrete 7 to be placed. For example, as shown in FIG. 6 (A), the rebar / steel bar 5a may be fixed by welding along the inner wall surface of the steel pipe 6, or as shown in FIG. 6 (B), a square steel material. 5b may be used, or a flat bar 5c or the like may be used as shown in FIG.

  In the illustrated example, the steel pipe 6 is a steel circular pipe, but a steel pipe such as a square pipe or a polygonal pipe can also be used. Moreover, although the said coupling structure 3 can also be built in the form which mounts on the ground, in order to reduce the displacement amount by earth pressure resistance, it builds in the state embedded in the ground mostly. Is desirable.

  The main pedestal column 4 is provided with a plurality of steps on the outer surface of the lower portion thereof, and in the example shown in the figure, there are provided support plates 8, 8,..., And this support plate arrangement portion K is substantially at the center of the coupling structure 3. It is embed | buried in the coupling structure 3 so that it may be located. Although the cross-sectional dimension of the main pedestal 4 is not particularly limited, it is approximately 300 to 3000 mm. The bearing plate 8 has a structure in which a ring plate is fixed around the main leg column 4 by welding or the like, but the planar shape of the bearing plate 8 may be a polygonal shape or the like. In this embodiment, the pressure plate method is adopted as the fixing method of the main pedestal 4. However, the anchoring material fixing method employed in the inverted T-shaped foundation 50 of FIG. 24 can be adopted. The bolt fixing method shown in FIG. 7 may be adopted.

  Further, in the illustrated example, a steel pipe column is shown as the main pedestal column 4 of the steel tower, but the main pedestal column 4 is connected by, for example, angle steel or a lattice bar (abdomen) in which a plurality of main materials are arranged in a zigzag shape. It is also possible to target assembled columns.

  As described above, both the pushing force and the pulling force act on the main pedestal column 4 depending on the direction of wind load, etc., so that both the pushing force and the pulling force can be handled. It is desirable that the misalignment prevention ribs 5 are disposed on the upper side and the lower side of the main support column 4 of the tower main pillar 4 as a boundary. Actually, as shown in the drawing, it is desirable to arrange the steel pipes 6 at substantially equal intervals in the vertical direction.

  As the main pile 1, regardless of the pile type, it can be any of steel pipe pile, cast-in-place pile, or ready-made pile, etc., but it has a large compressive strength and pulling strength, and can be easily constructed and carried in. It is desirable to use a reinforced concrete structure with cast-in-place and a pile body with a diameter of 250 to 600 mm. The construction of the pile body can be established by inserting an assembly bar into the drilled hole and filling it with high fluidity concrete, for example, when drilled in the ground by drilling. For the drilling of the ground, a rotary type or the like is used when the ground is weak, and a rotary hitting down-the-hole hammer (trade name) or the like is preferably used when the ground is a bedrock or a bedrock layer in the middle. can do.

  In the illustrated example, the main pile 1 is disposed at a position shifted toward the center of the steel tower on the mountain side of the slope with respect to the axis S of the main pedestal column 4 and at a position displaced toward the outside of the steel tower on the valley side of the slope. However, as shown in FIG. 3, it may be provided on an extension of the axis S of the main pedestal 4. A plurality of main piles 1 may be provided. For example, as shown in FIG. 4, one may be provided on both sides across the axis S in a plane. In the case where a plurality of piles are provided, they are arranged so that the central axis of the pile group is in the direction of the axis S of the main pedestal column 4.

  In the example of FIG. 2, the main pile 1 and the joint structure 3 are joined using a reinforcing bar fixing system in which fixing reinforcing bars 9, 9... You may employ | adopt the bearing plate joining system which fixes to the outer surface of the pile head inserted in the structure 3 by the bearing plate of the ring shape etc. provided so that it might protrude outward. Furthermore, as shown in FIG. 8, the steel rod 6 is joined to the beam member 12 laid horizontally on the lower side by bolting a steel rod extending from the pile body 1, or in some cases by welding. May be combined.

  The sub-pile 2 is a pile body provided in the ground along a plane direction connecting the foundation and the tower center P in plan view. There is no particular limitation on the pile type. For example, a steel pipe pile, a cast-in-place pile, or an off-the-shelf pile, or an anchor pile that resists only a pulling force can be used. The sub-pile 2 is also preferably made of cast-in-place reinforced concrete, and if necessary, a composite structure in which the vicinity of the joint with the steel pipe 6 is covered with a steel pipe.

  As shown in FIG. 2, the joining method with the steel pipe 6 is such that an insertion port 6a is formed in advance in the steel pipe 6 and the fixing bars 10, 10... Extending from the insertion port 6a to the sub pile 2 are arranged. In the case of a steel pipe pile, the head of the secondary pile 2 is joined to the outer surface of the steel pipe 6 by welding or the like, as shown in FIG. Alternatively, as shown in FIG. 8, the outer surface of the steel pipe 6 may be joined by bolts 14 and 14.

  The sub-pile 2 should just be arrange | positioned along the surface direction which connects a foundation and the steel tower center P by planar view. For example, as shown in FIG. 1 and FIG. 5, in the case of inclined ground, the secondary piles 2, 2... Of each foundation may be arranged toward the outer side of the steel tower on the mountain side of the slope. You may make it arrange | position toward the inner side of a steel tower about the foundation of a side. A plurality of sub-stakes 2 may also be provided. For example, as shown in FIG. 4, one may be provided on both sides across the plane connecting the foundation and the tower center P. When providing two or more, it arrange | positions so that the center axis | shaft of a pile group may correspond to the surface which connects a foundation and the tower center P. FIG.

  The angle θ formed by the main pile 1 and the sub-pile 2 is desirably 30 degrees or more and 90 degrees or less, preferably 40 degrees or more and 60 degrees or less, in order to resist the pulling force and the horizontal force with a good balance. . The sub-pile 2 preferably has a pulling strength of at least 20% of the pulling strength of the main pile 1. By the secondary pile 2 having a pulling strength of 20% or more of the main pile 1, the secondary pile 2 shares the decrease in the strength of the main pile 1 even after the pulling resistance force of the main pile 1 exceeds the maximum value. Therefore, the foundation is not pulled out rapidly, and it is possible to take a fracture form with high toughness.

  First of all, if the construction part of the joint structure 3 is excavated in the ground, drilling is performed from the wall surface of the excavation part, and the pile body 1, the fixing bar 9 and the auxiliary pile 2 are driven, and then the steel pipe 6 Is installed. In addition, in the wall surface of the steel pipe 6, the insertion port 6a of the fixing bar | burr 10 is previously formed in order to attain integration with the sub pile 2.

  Next, a predetermined reinforcing bar is arranged in the steel pipe 6, and the fixing bar 10 is inserted from the insertion port 6 a of the steel pipe 6. Then, if the base part of the main pedestal column 4 is positioned at a predetermined position in the steel pipe 6 and fixed by a temporary fixing member (not shown), concrete is placed.

  In addition, concrete 11 is also cast on the outer portion of the insertion opening 6 a of the steel pipe 6 to fix the head of the sub-pile 2 so as to be integrated with the coupling structure 3.

  Hereinafter, various experiments were conducted to verify the effect of the assembled pile according to the present invention and the behavior of the pile at the time of loading.

(1) Displacement characteristics of assembled piles In the actual site, as shown in FIG. 9, the beam 20 is fixed with reaction force piles 21 and 21, and the foundation composed of the main pile 1 and the auxiliary pile 2 is pulled out from the jack 22, The amount of displacement in the XY direction was examined. As a result, as shown in FIG. 10, it was found that the sub-pile 2 is displaced in a substantially orthogonal direction while being displaced in the vertical direction.

(2) Displacement In the same field test, as shown in FIG. 11, the displacement in the loading direction was taken on the horizontal axis, and the displacement was compared for each case of single pile and group pile. As a result, it has been found that the displacement of the pile pile can be suppressed more significantly at the same load. In the case of a single pile, it can be seen that the gradient decreases and the maximum proof stress is reached at a loading load of 6000 kN. It can be seen that the maximum proof stress is also greatly improved.

(3) Displacement behavior after peak As shown in FIG. 12, a loading test was conducted in a state where the upper ground of the test specimen was removed and the anchorage length of the pile was shortened, and the displacement behavior after the peak was investigated. As a result, as shown in FIG. 13, after the vicinity of the maximum load, the sub-pile 2 compensates for the decrease in the supporting force of the main pile 1, so that the load decrease is not abrupt and has a high toughness structure. I understand. From the figure, the load sharing rate of the secondary pile 2 after the peak is approximately 20%, and the secondary pile 2 may have a pulling strength of at least 20% or more of the pulling strength of the main pile 1. I understand.

(4) Stability analysis against changes in load direction of pile piles Since the direction of the load is not completely the same as the direction of the main pile 1, the stability when the load direction changes slightly is shown in FIG. Analysis was performed using an FEM analysis model. As shown in FIG. 15, the analysis case was made into three cases of the main pile 1 direction (0 ° direction) and ± 12 ° with respect to the direction of the main pile 1 in each case of the single pile and the group pile.

  As a result, it was found from FIG. 16 that shows the case of pulling and loading in the 0 ° direction, in the case of a pile pile, the displacement can be greatly suppressed. In particular, in the case of FIG. 17 showing the case of pulling and loading in the trough side −12 ° direction, the difference in the amount of displacement became considerably significant.

  Moreover, from FIG. 18 which compares the horizontal displacement and the vertical displacement at the maximum load, in the case of a pile pile, even if the loading direction changes, the displacement is stable within a certain amount and direction. In the case of a single pile, it can be seen that the displacement direction and quantity vary greatly depending on the loading direction. Furthermore, from FIG. 19 which compares the horizontal load and the vertical load at the maximum load, it is possible to maintain a stable proof stress even if the loading direction changes in the case of a group pile, but in the case of a single pile It was found that the bearing capacity could be greatly reduced depending on the loading direction (case of valley side -12 °).

(5) Comparison of foundation deformation and cross-sectional force by overall model analysis As shown in Fig. 20, the entire tower is modeled in a frame (Fig. 20 is a two-dimensional model but actually a three-dimensional model) However, it analyzed about the case of the group pile foundation based on this invention, and the case of a single pile foundation. In addition, as shown in FIG. 21, springs were considered in the pile axis direction and the pile axis orthogonal direction in the main pile and the sub pile, respectively. The analysis results are shown in FIG. 22 and FIG.

  FIG. 22 shows the horizontal displacement of each foundation. The single pile case generally has a large horizontal displacement. In particular, the C-leg where the compressive force acts is considerably larger than the pile. Compared to this, it can be seen that the displacement of each foundation is suppressed in the case of the pile pile.

  FIG. 23 compares the cross-sectional force (shearing force and bending moment) generated in the main pile in each case of the single pile and the group pile. From this figure, it can be seen that the cross-sectional force of the main pile can be significantly reduced by using the assembled pile.

It is a figure which shows the planar structure of a steel tower foundation. The basic structure of a steel tower is shown. (A) is a longitudinal sectional view and (B) is a transverse sectional view. It is a longitudinal cross-sectional view which shows the modification (the 1) of a foundation structure. It is a cross-sectional view showing a modification (No. 2) of the foundation structure. It is a longitudinal cross-sectional view which shows the modification (the 3) of a foundation structure. (A)-(C) are figures which show the modification of the rib 5 for slip prevention. It is a longitudinal cross-sectional view which shows the modification (the 4) of a foundation structure. It is a longitudinal cross-sectional view which shows the modification (the 5) of a foundation structure. It is a front view which shows the test body (the 1) of a field experiment. It is a horizontal displacement-vertical displacement diagram. It is a loading direction displacement-loading load figure. It is a front view which shows the test body (the 2) of a field experiment. It is a displacement-action load figure of a joint part. It is a FEM analysis model figure. It is a figure which shows the loading direction case of a load. It is a displacement-load figure of the drawing loading case of 0 degree direction. It is a displacement-load figure of a drawing loading case of trough side -12 degrees direction. It is a horizontal displacement-vertical displacement figure at the time of the maximum load in FEM analysis. It is a horizontal load-vertical load figure at the time of the maximum load in FEM analysis. It is a model figure of a frame analysis. It is a spring setting figure with respect to a pile. It is a horizontal displacement figure of each foundation. It is sectional drawing (shearing force, bending moment) figure which arises in a main pile. It is a longitudinal cross-sectional view of the conventional inverted T-shaped foundation. It is a longitudinal cross-sectional view of the conventional deep foundation. It is a figure which shows the destruction form (the 1) of a footing. It is a figure which shows the destruction form (the 2) of a footing.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Main pile, 2 ... Sub-pile, 3 ... Connection structure, 4 ... Main pedestal column, 5 * 5a-5c ... Ribbing rib, 6 ... Steel pipe, 7 ... Concrete, 8 ... Bearing plate, 9 * 10 ... Fixing muscle

Claims (6)

A foundation structure for supporting each main pedestal column of a steel tower, wherein the foundation structure includes one or more main piles provided in the ground along a direction substantially coinciding with the direction of the main pedestal column; One or more sub-piles provided in the ground along the plane direction connecting the foundation and the tower center in plan view, and the main pile and sub-pile are combined, and the base of the main pedestal is fixed Ri and Do and a coupling structure, said coupling structure, concrete and structs reclamation by pouring into steel tube, the top of the main pile on the lower surface side of the coupling structure are joined, the side surface The foundation structure of the steel tower characterized by the above-mentioned . The steel pipe, the inner wall surface, the base structure of the tower according to claim 1 having a fixedly provided been displacement preventing ribs in the circumferential direction over a plurality of stages in the vertical direction. The steel tower foundation structure according to claim 1 , wherein an angle formed by the main pile and the sub-pile is not less than 30 degrees and not more than 90 degrees. The foundation structure of the steel tower according to any one of claims 1 to 3 , wherein the main pile is a pile body having a reinforced concrete structure and a diameter of 250 to 600 mm. The said sub pile is an anchor pile or a reinforced concrete structure, The foundation structure of the steel tower in any one of Claims 1-4 . The Fukukui the substructure of tower according to any one of claims 1-5 having at least 20% or more of the pulling strength of the pull-out strength of the main pile.

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