JP7709630B2 - Method for toppling a tower-like structure using a concrete foundation and base flange - Google Patents

Description

The present invention relates to a method for toppling a tower-like structure, such as a power-generating wind turbine, by utilizing a concrete foundation and a base flange or a similar reinforced concrete plate that serves as the foundation, to topple the tower-like structure for dismantling.

Structures are demolished due to deterioration over time or to replace equipment, but if the structure in question is a tall, so-called tower-like structure, the standard procedure is to set up scaffolding, begin by dividing the structure into smaller pieces at the top, then use a crane or other device to lower it down to the lower sections, and finally remove the foundation.

In order to reduce the amount of work at height during the above-mentioned demolition, thereby increasing the safety of workers and reducing the amount of labor required to complete the demolition quickly, known techniques for knocking down tower-like structures for demolition include those disclosed in Patent Document 1 (Method of knocking down a regenerative furnace for a hot air stove) and Patent Document 2 (Method of knocking down a tower-like structure using its foundation).
The technology disclosed in Patent Document 1 relates to a technique in which the base of a structure is reinforced in some way to ensure an axis of toppling, and then the direction of toppling is controlled by cutting into the structure itself, thereby ensuring safe toppling.
The technology disclosed in Patent Document 2 has developed from the issues with the technology in Patent Document 1, and relates to a technology that creates a strong axis of tipping by cutting out the concrete foundation, thereby controlling the direction of tipping and achieving safe tipping.
The notches in Patent Documents 1 and 2 are less than half the size of the bottom, and even with the notch, the center of gravity is still on the safe side of the tipping axis, so an external force must be applied to start the tipping, resulting in a forced tipping. For example, Patent Document 2 describes a method of using a jack to push up the device.

Relisted No. 2018/189852 (Assessment date: 2021/08/10) Patent No. 4790357

In Patent Document 1, the axis of overturning is created by reinforcing the base, and in Patent Document 2, the axis of overturning is created by utilizing the strength of the concrete foundation. The most important issue in the overturning method is where to find a strong axis of overturning.

According to Patent Document 1, there is a method for dismantling a tower-shaped structure, a "hot air stove regenerative furnace," in which filler is packed into the bottom of the cylindrical regenerative furnace to increase its strength, and this part is cut out to prevent buckling due to insufficient strength when the furnace is overturned. This limits the direction of overturning, allowing the furnace to be overturned safely.

However, the process of filling the concrete with filler requires time and waiting time while the filler hardens. In addition, the filler becomes industrial waste at the final stage of demolition.

According to Patent Document 2, without using "reinforcement of the cylindrical bottom" as in Patent Document 1, a concrete foundation buried in stable ground is utilized, and the concrete foundation is dug down to and cut out to create a strong axis of tipping, limiting the direction of tipping and ensuring safe tipping.

However, digging down to the concrete base takes a lot of man-hours.

In this invention, when a flange or similar "reinforced concrete base" is found in the concrete foundation and base, and the disk (= flange) at the bottom of the column of the tower-like structure is fixed by tightening nuts to a number of bolts firmly fixed to the concrete base along its circumference, a notch larger than half of the bottom of the base is made, and a situation is created in which the center of gravity of the entire structure is on the side of the tipping axis in the direction of tipping, so that the bolts in the notch are cut off, but the bolts that have not been cut are kept stationary by the bolts that have not been cut , and while holding the bolts on the tipping axis, the bolts that have not been cut are cut from the inside to the outside of the tipping axis, so that at a certain point the bolts that have not yet been cut will not be able to withstand the tipping force and will be torn off, causing the structure to naturally tip over and topple the tower-like structure.

The invention described in claim 1 to achieve the above object is:
The method includes a foundation exposing step of exposing the bottom of the base flange only to a minimum extent necessary for a notch for tipping, a horizontal cutting step of cutting the bottom of the base flange horizontally to a position larger than half of the bottom and determined by a pre-calculated method, a notch creating step of cutting obliquely upward from the bottom of the flange surface toward the central cross section of the horizontal cut, a removing step of removing the notch, an installation step of installing a load sensor and a support material in the notch, and a tipping step of tipping the tower-like structure together with the base flange, with the meeting line of the horizontal cutting step and the notch creating step as the tipping axis.

With this configuration, there is no need to "fill with filler and then dispose of it later" as in Patent Document 1, nor is there a need to "dig down to the huge base buried in the ground" as in Patent Document 2.The tower-like structure can be easily, safely and quickly toppled using the foundation flange, a strong part of the structure, as the axis of toppling.

In this type of toppling, the foundation flange, a strong part that is part of the original structure, is used as the strength of the toppling axis (toppling fulcrum), which is able to resist buckling and allows the tower-like structure to topple in the planned direction, making it safe.

The invention of claim 2 is characterized in that the center of gravity of the entire structure is moved to the tipping side of the tipping axis, and the remaining bolts are successively cut from a state in which they are held in place only by the tension of the bolts, and at a certain point the remaining bolts are unable to withstand the tipping force and are torn off, thereby allowing the structure to tip naturally without the application of a large external force.

The invention of claim 3 is characterized in that a load sensor is installed in the cutout portion and monitored to obtain warning signs of sudden tipping (unexpected tipping) during construction, and the separation of the bolts during the tipping process is adjusted numerically, rather than relying on intuition or experience.
As described in claim 2, the center of gravity is on the tipping side of the tipping axis, making sudden tipping more likely to occur than when the center of gravity is on the safer side as in the previously mentioned patents, and therefore such measures are taken.

According to the present invention, the lower part of the base flange is cut horizontally, and then a notch is made diagonally upward from the lower part and removed, and the tower-like structure is toppled using the meeting line between the horizontal cut and the diagonally upward cut as the axis of toppling. This makes it possible to easily overturn a tower-like structure.

By making the cutout at the bottom larger than half, bringing the center of gravity of the entire structure toward the tipping side from the tipping axis and maintaining a stationary state using the tension of the remaining bolts, and then cutting the bolts from that state, the structure can be naturally tipped over without the need for a large external force.

By installing and monitoring load sensors, it is possible to predict sudden falls (unexpected falls) during construction.
The overturning can be carried out without the need for "extra reinforcement" or "large-scale excavation of the ground" as in Patent Documents 1 and 2.

FIG. 1 is a side view showing a tower-like structure according to an embodiment of the present invention. 1 is a diagram showing the cuts, notches, and inversion axis of the base flange and its surroundings according to the present embodiment; 11A and 11B are diagrams illustrating bolt cutting in a down-setting process according to the present embodiment; ~ These are schematic diagrams of a concrete chimney 40, a distillation tower 50, a pressure reaction tower 60, a steel tower-supported chimney 70, and a tripod-supported chimney 80, respectively.

Next, an embodiment of the present invention will be described in detail with reference to the drawings.
A method for knocking down a tower-like structure for dismantling it will be described with reference to Figs.
FIG. 1 is a side view showing a tower-like structure according to an embodiment of the present invention, FIG. 2 is a diagram showing the cut, notch, and overturning axis of the base flange and its surroundings in the method of collapsing a tower-like structure, and FIG. 3 is a diagram showing the bolt cutting in the collapsing process according to this embodiment.

As shown in FIG. 1, in this embodiment, the tower-like structure 10 is a wind turbine for generating electricity. However, as will be described later, the tower-like structure of the present invention is not limited to a wind turbine for generating electricity.

The term "base flange" is a general term for the "reinforced concrete base," and its shape is not limited to that shown in Figure 2.

The tower-like structure 10 is connected to a foundation flange via a tower 12, and the base flange is fixed to a foundation 13 by bolts or the like.

Next, each step of the tower-like structure collapse method of the present invention will be described. The tower-like structure collapse method of the present invention includes a foundation exposing step, a horizontal cutting step, a notch creating step, a removal step, a sensor installation step, and a collapse step.

[Basic exposure process]
If the foundation is not exposed enough for the cutting process described below, excavate around it as much as necessary to create an exposed portion.

[Horizontal cutting process]
Next, a horizontal cut is made below the base flange to a pre-calculated distance 21, which is greater than the bottom radius. The cut can be made, for example, with a wire saw.

[Notch creation process]
Next, a cut is made obliquely upward from below the cut surface toward the central cutting line 22 to create a notch. The cutting can be performed using, for example, a wire saw.

[Removal process]
Next, the notched portion formed in the notching process is removed. This can be done, for example, by fixing a wire rope (not shown) to the notched portion 23 and pulling the other end with a winch or the like.

[Sensor installation process]
A load sensor is installed in the cutout, and the pressure applied from above the cutout is monitored and adjusted so that it does not exceed zero, allowing the remaining bolts, etc. to maintain the frame stationary even when the center of gravity of the frame is on the tipping side.
This can be a "support bar type with a load sensor and support material" as shown in Figure 3, but it doesn't have to be this way as long as it can observe the pressure. For example, it can be substituted with a general-purpose heavy machine with a load sensor.

[Falling process]
Next, in the process of toppling, since the center of gravity is on the tipping side in the present invention, no external force strong enough to prevent tipping is required as described above. In order to prevent the tipping axis from shaking and maintain its strength by holding the bolt 31 corresponding to the tipping axis (two bolts are held on each side in the figure, but any number can be used depending on the situation), the remaining bolts are cut horizontally from the inside to the outside under the base flange surface while avoiding the area around this bolt (see Figure 3). This can be done remotely using a wire saw (not shown in the figure), so it can be achieved even if the worker is not near the site just before the tipping, which is also beneficial for ensuring the safety of the worker.

Furthermore, in the power-generating wind turbine shown in Figure 1, the position of its center of gravity is not necessarily at the center of the support pillar, and in some cases it may be difficult to determine the position of the center of gravity. Even in such cases, the turbine can be safely tilted by tipping it in a direction perpendicular to the axis of rotation of the turbine, in other words, sideways, rather than in the direction of the turbine's axis of rotation (forward or backward).

In the above embodiment, a power-generating wind turbine is exemplified as a tower-shaped structure, but the present invention is not limited to this and may be any tower-shaped structure having a base flange or a similar reinforced concrete plate as a foundation. For example, a concrete self-supporting chimney 40 (FIG. 4), a distillation tower 50 (FIG. 5), a pressure reaction tower 60 (FIG. 6), a steel tower-supported chimney 70 (FIG. 7), a tripod-supported chimney 80 (FIG. 8), and various other tower-shaped structures may be mentioned.

10 Tower-like structure 12 Tower 13 Base 20 Base flange 21 Distance determined by calculation 22 Center cutting line (= overturning axis)
23 Notch portion 31 Bolt 32 Wire saw (only wire is shown)
33 Weight sensor

Claims (3)

1. A method of performing overturning utilizing a concrete foundation and base flange, comprising:
The method includes a foundation exposing step of exposing the bottom of the base flange only to the minimum extent necessary for a notch for tipping, a horizontal cutting step of cutting the bottom of the base flange horizontally to a position larger than half of the bottom and determined by a pre-calculated method, a notch creating step of cutting the base flange obliquely upward from below toward the central cross section of the horizontal cut, a removing step of removing the notch, a sensor installation step of installing a load sensor and a support material in the notch, and a tipping step of tipping the tower-like structure together with the base flange, using the meeting line of the horizontal cutting step and the notch creating step as the tipping axis,
A method for toppling a tower-like structure, characterized in that a strong axis of toppling is created by utilizing a concrete foundation and a base flange, thereby causing the structure to topple. 2. A method for toppling a tower-like structure as described in claim 1, characterized in that the center of gravity of the entire structure is moved to the tipping side of the tipping axis, and the bolts present in the cut-out portion are cut off by the removal process, but the bolts that have not been cut are held in place by the tension of the remaining bolts alone, and at a certain point the remaining bolts are unable to withstand the tipping force and are torn off, allowing the structure to tip naturally without the application of a large external force. A method for collapsing a tower-like structure as described in claims 1 and 2, in which a load sensor is installed in the cutout portion and monitored to obtain a sign of a sudden collapse (unexpected collapse) during construction, and "bolt separation" in which the bolts are sequentially cut from a state in which the bolts are held in place only by the tension of the remaining bolts that have escaped being cut during the collapse process is adjusted numerically rather than by intuition or experience.