JP7849062B2 - Steel bridge maintenance methods - Google Patents

Description

This invention relates to a maintenance method for steel bridges, which includes performing blast treatment on the steel portions of existing steel bridges.

Traditionally, existing steel bridges have undergone maintenance (preventive maintenance) to replace paint that has deteriorated due to aging and corrosion. Maintenance requires removing rust and old paint, and in recent years, blast cleaning (Type 1 surface preparation) has been used to remove rust and paint, followed by the application of new paint.

In this blasting process, abrasive materials, rust, and old paint films are scattered, so it is necessary to create scaffolding to provide a working space that properly covers the steel parts. Generally, as disclosed in Patent Document 1, for example, the blasting equipment is installed at a predetermined location outside the scaffolding, and the hose is brought inside the scaffolding to perform the work.

Japanese Patent Publication No. 2019-214081

However, in the case of steel bridges spanning the sea or rivers, there is no space to place blast equipment beneath the bridge. Therefore, a method was adopted where, for example, road traffic on the bridge was temporarily restricted, and then the blast equipment was installed in the restricted area. However, this presented problems such as the time and cost involved in starting and ending road restrictions, as well as causing traffic congestion.

Furthermore, in order to address the increasing scale of construction projects and the construction of long-span bridges over the sea and rivers, it was necessary to consider not only road regulations but also improvements in machine output (such as increasing suction power). On the other hand, there was also a need to respond to the global transition to decarbonization. Additionally, commonly used suspended scaffolding lacked the strength to support large machinery.

Therefore, the present invention aims to provide a maintenance method for steel bridges that eliminates the need for road restrictions and other such measures.

The present invention relates to a steel bridge maintenance method that includes performing blast treatment on the steel portion of an existing steel bridge, comprising: a scaffolding formation step of forming a scaffold for performing the blast treatment on the steel bridge while suspending it from the bridge; a blast device placement step of arranging a blast device on the scaffolding; and a blast step of performing blast treatment by projecting abrasive material onto the steel portion using the blast device, and recovering the projected material into the blast device, wherein the projected material recovered into the blast device is reused for the blast treatment.

In this configuration, by positioning the blasting device on the scaffolding, there is no need to create space on the ground surface beneath the steel bridge to install the blasting device. Furthermore, since road closures are not required during maintenance work on steel road bridges, traffic congestion problems are resolved. In this invention, scaffolding with sufficient strength is used to install the blasting device.

Furthermore, the proposed configuration includes a blasting apparatus arrangement step that divides the area into a specific hazardous substance area where the steel portion is located and a non-specific hazardous substance area, so that the specific hazardous substances contained in the coating removed from the steel portion during the blasting process are recovered by the blasting apparatus.

This configuration prevents the leakage of specific hazardous substances outside the scaffolding.

Furthermore, a configuration is proposed in which the blasting apparatus placement process includes placing a generator, which serves as the power source for driving the blasting apparatus, and a compressor for driving the blasting apparatus, on the scaffolding.

This configuration allows for centralized management of all equipment, including the power generation system. In particular, because no power source is required outside the scaffolding, it eliminates the need to secure a separate power supply even at isolated work sites such as steel bridges on the sea.

Here, a configuration is proposed in which the blasting equipment placement process includes placing oil leakage prevention means on the scaffolding to prevent oil discharged from the generator and compressor from leaking from inside the scaffolding into the space outside the scaffolding.

This configuration prevents oil from leaking to inappropriate locations.

The steel bridge maintenance method of the present invention has the effect of eliminating the need for road closures and other restrictions when performing blast treatment.

This is an explanatory diagram of a steel road bridge according to the example.

The following describes in detail an embodiment of the steel bridge maintenance method according to the present invention. Note that the present invention is not limited to the embodiments shown below, and design modifications can be made as appropriate.

As shown in Figure 1, a steel road bridge 1 is constructed with a steel foundation 2 and a road 3 on top for vehicle traffic. A maintenance method for such a steel road bridge 1 involves first forming scaffolding 10 to cover a predetermined portion of the steel foundation 2 (scaffolding formation process). In this case, it is common practice to form the scaffolding 10 by suspending it from the steel road bridge 1 using suspension devices 11 such as suspension chains.

Furthermore, in the scaffolding formation process described above, an oil pan 31 is placed in the area where the generator 30 and compressor 32 are located to prevent oil from leaking outside the scaffolding when the scaffolding 10 is formed. Alternatively, instead of the oil pan 31, a metal plate material may be used on the scaffolding floor to prevent oil leakage.

Next, the blasting device 20 and the generator 30, which powers the blasting device 20, are placed on the formed scaffolding (blasting device placement step). Furthermore, a compressor 32 is also placed. The blasting device 20 has the function of storing abrasive material (projection material) for grinding the steel material 2, projecting the abrasive material, and recovering the projected abrasive material. The compressor 32 drives the blasting device 20 to generate compressed air used when the abrasive material is projected. The generator 30 supplies power to the blasting device 20, compressor 32, etc. All of these are placed on the outside (external space side) of the steel material 2 within the scaffolding 10. Note that when the abrasive material is recovered to the blasting device 20, debris such as rust and peeled paint generated during the blasting process is also recovered.

The waste collected here is accumulated in a designated area of the blasting device 20 and periodically transported away from the scaffolding.

After the blasting device 20, generator 30, compressor 32, etc., are positioned as described above, the blasting device 20 is used to perform blasting on the steel materials 2 at predetermined locations within the scaffolding 10 (blasting process). At this time, the predetermined location 40 within the scaffolding 10 where the blasting is performed is further partitioned to prevent debris from scattering to the outside. In this embodiment, the predetermined location 40 is the specified hazardous substance area α, and the rest of the scaffolding area is the non-specified hazardous substance area β. Specifically, the specified hazardous substance area α is divided into a blasting device installation area containing the blasting device 20, and a blasting work area partitioned from the device installation area by an isolation wall S, for example, made of a predetermined protective sheet.

The following effects can be achieved by carrying out maintenance work on the steel bridge in this manner.

This eliminates the need to install blasting equipment, generators, etc., outside the scaffolding, thus eliminating the need for selecting and restricting installation locations. For example, it eliminates the need for lane closures on steel road bridges built over the sea or rivers, reducing concerns about traffic congestion and significantly lowering construction costs.

This prevents specific hazardous substances from leaking outside the scaffolding.

It can also handle oil leaks from generators and compressors.

Furthermore, for example, the leakage of specific hazardous substances can be further prevented by making the scaffolding a cleanroom. Noise reduction measures can be implemented by covering the scaffolding with soundproof panels, etc. If electricity for the blasting equipment can be brought in from an external source, carbon dioxide emissions can be significantly reduced by, for example, installing a cubicle system. In this case, if the Fire Service Act requires a certain distance between the machines, one proposed solution is to create a partition wall using, for example, steel plates. Alternatively, the blasting equipment may be placed on rails laid on the scaffolding, and the blasting process can be carried out by moving the blasting equipment along the rails.

1 Steel road bridge (steel bridge)
2 Steel material (steel part)
3. Road 10, Scaffolding 20, Blasting device 30, Generator 31, Oil pan 32, Compressor 40, Designated location (Specific hazardous substance area α)

Claims (1)

A steel bridge maintenance method that includes performing blast treatment on the steel portion of an existing steel bridge , which has a steel foundation and on which vehicles pass ,
A scaffolding formation step is to form a scaffolding for performing the blast treatment on the steel bridge, while suspending it from the steel bridge using suspension devices ,
A blast apparatus arrangement step involves arranging a blast apparatus on the aforementioned scaffolding that has the function of storing the blast material, blasting the blast material, and collecting the blasted blast material .
A blasting process is performed by projecting a projectile onto the steel portion using the blasting apparatus, and the projectile is recovered into the blasting apparatus.
Includes,
The abrasive material recovered in the blasting apparatus is reused in the blasting process.
The blasting apparatus placement step includes:
The area is divided into a specific hazardous substance area where the steel portion is located and a non-specific hazardous substance area other than the specific hazardous substance area, and the specific hazardous substances contained in the coating film peeled off from the steel portion in the blasting process are recovered by the blasting device.
The aforementioned area containing specific hazardous substances is divided into a blast equipment installation area that includes a blast equipment, and a blast work area that is separated from the blast equipment installation area by an isolation wall made of a predetermined protective sheet.
The scaffolding also includes a generator that serves as a power source to drive the blasting device, and a compressor for generating compressed air used when the blasting device is driven and the abrasive material is projected, and the generator also supplies power to the compressor.
As a means of preventing oil leakage to prevent oil discharged from the generator and compressor from leaking from inside the scaffolding into the space outside the scaffolding, this includes placing an oil pan or a metal plate on the scaffolding in the area where the generator and compressor are located.
The blasting process includes:
When the abrasive material is collected back into the blasting machine, debris such as rust and peeled paint generated during the blasting process is also collected.
The aforementioned waste is collected in a designated area of the blasting device and then transported away from the scaffolding.
A steel bridge maintenance method characterized by the following features.