JPS6024725Y2 - shock absorber - Google Patents

Description

[Detailed description of the invention] This invention is a shock absorbing device that absorbs the collision energy and alleviates the collision when a ship collides with an underwater structure such as a bridge pier. The present invention relates to a shock absorber that reduces damage to a ship and protects underwater structures even in the event of a collision at high speed by rationally combining shock absorbers with different load-deformation characteristics.

Conventionally, as this type of shock absorbing device, there is a floating shock absorbing device that is composed of an upper shock absorbing block mainly formed of a brittle fracture material and a lower shock absorbing block mainly formed of a plastically deformable body.

The method for connecting the upper and lower shock absorbing blocks is as follows:
Methods used include integrating the reinforcing material forming the surface layer of the upper block with the surface layer of the lower block, and joining the upper and lower blocks with bolted nuts.

In the case of the upper block, the brittle fracture material, which is the main material, is used as a reinforcing member for floating shock absorbers against external weather forces, buoyancy, and self-weight when a ship does not collide. Since the stress level is low, most of the external force is carried by the reinforcing material forming the surface layer of the upper block.

On the other hand, in terms of shock absorbing performance in the event of a ship collision, the shock absorber must absorb the collision energy by crushing the colliding ship without damaging it due to a collision force that is less than the strength of the ship.

Therefore, if the crushing strength of the impact surface of the shock absorber is kept below the strength of the colliding ship, it will not be possible to secure the safety factor against external forces when the ship is not colliding, which is generally required for marine structures; In order to ensure a safety factor against external forces, the reinforcing material that forms the surface layer must be made stronger, which has the disadvantage that the crushing strength of the collision surface becomes equal to the strength of the colliding ship, and it no longer functions as a shock absorber.

On the other hand, the collision probability based on the size of the ship is greatest for shallow, shallow medium-sized ships with a fully loaded displacement of several thousand tons or less, and in the event of a collision with a medium-sized ship, the collision energy is mainly absorbed by the upper block. There are many occasions when only the upper block damaged by a collision with a medium-sized ship is replaced.

On the other hand, as mentioned above, the upper block and lower block are connected by integrating or bolting them together on the surface layer of both blocks, so replacing the upper block requires floating the connecting part to the surface of the water or working underwater to remove the connecting part. There is no need to cut or remove bolts, making the upper block easier to replace.

The present invention improves the strength of a shock absorbing device using brittle fracture materials and plastically deformable bodies against various external forces during non-ship collision without reducing the shock absorbing performance of the shock absorbing block, which is mainly made of brittle fracture materials. The purpose is to improve the replaceability of shock absorbing blocks mainly made of brittle fracture materials.

The shock absorber of the present invention is composed of an upper block mainly composed of a brittle fracture material, a lower block mainly composed of a plastically deformable body, and a rigid body for attaching these blocks. It is used as a floating structure around underwater structures such as bridge piers.

Further, a low reaction force elastic shock absorber may be provided on the front surface of the upper block.

With this configuration, the external force when a ship does not collide is mainly borne by the mounting rigid body and the lower block, so there is no need to strengthen the reinforcing material forming the skin layer of the upper block, which is often subject to collisions.

That is, it is possible to improve the strength of the shock absorber against external forces when the ship does not collide without impeding the shock absorbing performance.

When replacing the upper block, the rigid mounting body can be equipped with a shock absorber to raise the fixed connection part of the upper block, which is below the water surface, to the surface of the water.
Attaching and detaching the upper block can be done above the water surface, making it easy to replace.

In addition, the low reaction force elastic shock absorber, which can be used repeatedly, is placed close to the water surface at the front of the upper block of the shock absorber, so that the collision energy is equivalent to the collision of a small boat with a fully loaded displacement of several tens of tons, or the collision of a ship. In the event of a relatively small collision or contact, the impact energy can be absorbed by this low-reaction force elastic buffer, and the upper block and lower block, which are mainly composed of brittle fracture materials or plastically deformed materials, will not be destroyed. There is no need for the shock absorber to bend or deform, and the function of the shock absorber can be maintained.

Next, the shock absorbing device according to the present invention will be described in detail with reference to preferred embodiments shown in the accompanying drawings.

As shown in Fig. 1, the shock absorber of the present invention is installed near the water surface 2 in a floating manner for protection on the outer periphery of an underwater structure 1 such as a bridge pier, and consists of a rigid body 3 for mounting, an upper block 4 and a lower block 5. It is configured.

The mounting rigid body 3 exists between the upper and lower blocks described later and the underwater structure, and is connected to the upper and lower blocks and floats around the outer periphery of the underwater structure.

The mounting rigid body 3 is a rigid body assembled into an appropriate shape using metal material, concrete material, or the like.

The upper block 4 is made by enclosing a brittle fracture material 6 with a reinforcing material 7.

Typical examples of brittle fracture materials include synthetic resin foams such as rigid polyurethane foam and phenol foam, and inorganic foams such as foamed concrete, perlite, and foamed glass. There is almost no distortion up to the limit value, and when this limit value is exceeded, the shock absorber is in a state where it is unable to return to its original shape. used.

The reinforcing material 7 is formed into a box shape mainly made of, for example, a metal plate, wire mesh, FRP, woven fabric, nonwoven fabric, rubber, or the like.

The crushing strength of the collision surface of this reinforcing material 7 is smaller than the strength of the colliding vessel.

As a result, the hulls of ships that collide with each other are not destroyed and exhibit excellent buffering capacity.

The lower block 5 is a plastically deformable body that is appropriately combined to form an air chamber 8, and is made of metal materials such as thin steel plates and various shaped steels, and threatening resin materials such as FRP and PVC, and is resistant to external forces up to a certain limit value. This is a shock absorber that is mainly made of a material that causes almost no distortion, but if this limit value is exceeded, it will flow and become permanently deformed, that is, it will mainly exhibit plastic deformation.

In the illustrated example, the rigid body 3 and the upper block 4 and the upper block 4 and the lower block 5 are removably but fixedly connected by a fixture 9.

Typical examples of the fitting 9 include anchoring devices such as bolt nuts, flange fitting frames, keys/knock pins, and chains.

A low reaction force elastic body 10 can be mounted on the front surface of the upper block 4 at a position close to the water surface 2 by suitable mounting means 11.

Low reaction force elastic bodies are mainly rubber fenders, rubber exhaust materials such as polyethylene foam, or pneumatic fenders, and have a lower initial compressive reaction force per unit impact area than brittle fracture materials or plastically deformable bodies. It is made small.

Next, the buffering action of the shock absorber when a ship collides with the shock absorber having such a configuration will be explained.

If the colliding vessel is a small vessel (full displacement of several tens of tons or less), the collision energy is mainly absorbed by the elastic deformation of the low-reaction force elastic body attached to the front of the shock-absorbing block, which is mainly made of brittle fracture material. However, in the case of medium-sized ships (with a fully loaded displacement of several thousand tons or less, not including small ships), the collision energy is mainly absorbed by the brittle fracture of brittle fracture materials, and in the case of large ships (ships with a fully loaded displacement of several hundred tons). In this case, the brittle fracture of the brittle fracture material and the plastic deformation of the plastically deformed body mainly absorb the collision energy.

In this way, even when various types of ships, from small ships to large ships, collide at different speeds, damage to the ships can be reduced and underwater structures can be reduced by rationally combining shock absorbers with different load-deformation characteristics. Protect.

Next, the strength characteristics of the shock absorber configured as described above against various external forces when a ship does not collide will be explained.

External forces when a ship does not collide include tidal current force, wave pressure, hydrostatic force, uplift force, buoyancy force, own weight, and external forces due to sagging and hogging, and shock absorbers have sufficient resistance to these external forces. Must do.

The main strength member of the shock absorber is the lower shock absorbing block, which is mainly composed of a rigid mounting body and a plastically deformable material, and is particularly effective against external forces such as uplift force that act on the low parts of the shock absorber, and when the shock absorber unit becomes long. The moment and shear force that act on the entire shock absorber due to satgging and hogging can be prevented from acting on the upper shock absorbing block, which is mainly made of brittle fracture material.

In addition, during temporary installation or transportation of the shock absorber, when installing the shock absorber on an underwater structure such as a bridge pier, or when replacing the upper shock absorbing block due to a ship collision after installation, for example, when hoisting the shock absorber, the suspension point should be adjusted. By providing it on the top surface of the mounting rigid body, the work can be done easily and the stress due to its own weight during lifting does not have to be applied to the brittle fracture type shock absorbing suspension at the top.

Therefore, the external forces that act on the upper block include tidal current force, wave pressure, hydrostatic pressure that acts as a horizontal compressive force on the front surface of the upper block itself, buoyancy force that acts in the vertical direction, and the own weight of the upper block. Of these external forces, the compressive stress level of the brittle fracture material may be made strong enough to withstand the horizontal compressive force.

However, the degree of compressive stress of the brittle fracture material is made lower than the crushing strength per unit area of the impact receiving surface of the colliding vessel to prevent damage to the colliding vessel.

The buoyant force acting in the vertical direction occurs when a brittle fracture material whose unit volume weight is smaller than It/d (unit volume weight of water) is used by being pushed down below the water surface.

In this case, the restraining force is mainly applied to the reinforcing material forming the surface layer of the upper block.

As explained above, the main strength members of the shock absorber can be the mounting rigid body and the plastically deformable lower block, and the brittle fracture type absorbs the collision energy of colliding vessels, especially medium-sized vessels and smaller, which have a high collision frequency. It is possible to improve the resistance of the shock absorber against external forces during non-ship collision without impairing the shock absorbing performance of the upper block.

Next, the replaceability of the upper block of the shock absorber configured as described above will be explained.

When replacing the upper block due to a ship collision etc. after installation,
A suspension point is provided on the top surface of the rigid mounting body, and a shock absorber unit that requires replacement is lifted on a crane ship, etc., and the rigid mounting body of the upper block or the connection part with the lower block is lifted above the water surface and then damaged. The upper block can be removed and replaced by a new upper block.

Since there is no work required underwater, the efficiency of replacement work can be significantly improved.

As is clear from the above explanation, the shock absorbing device according to the present invention has the following advantages.

(1) It is possible to improve the resistance of the shock absorber against external forces when the shock absorber does not collide with a ship without impairing the shock absorbing performance of the brittle fracture shock absorbing book.

(2) The brittle fracture type shock absorbing block can be easily replaced.

The shock absorbing device of the present invention is not limited to the above-described one, but can be modified in various ways as described below.

(1) Inside the reinforcing material forming the outer skin layer of the upper block, a low-reaction force elastic buffer made of an elastic foam such as polyethylene foam can be placed in advance on the front surface of the brittle-destructible material together with the brittle-destructible material.

(2) Put brittle breakage material in a part of the interior of the pneumatic fender (for example, airflock fender) that has a mounting plate, and form an air chamber in the front of the inside of the pneumatic fender to prevent ship collisions. Initially, the air compressive elasticity of the pneumatic fender absorbs the collision energy, and when the pneumatic fender is subjected to even higher pressure, the front impact surface of the pneumatic fender comes into contact with the brittle fracture material inside, causing the brittle fracture material to become brittle. Destruction can also be added to absorb collision energy.

This configuration is effective because it simplifies the combination structure of the low reaction force elastic shock absorber and the brittle fracture type upper block, and improves the transportability, replaceability, and manufacturability of the upper block. .

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the shock absorber of the present invention installed on a bridge pier, and FIG. 2 is a cross-sectional view taken along the line ■--■ in FIG. Explanation of symbols, 1... Underwater structure, 2...
・Water surface, 3... Rigid body for mounting, 4... Upper block, 5... Lower block, 6...
...Brittle fracture material, 7...Reinforcement material, 8...
- Air chamber, 9... Mounting tool, 10... Low reaction force elastic body, 11... Mounting means.

Claims (1)

[Scope of utility model registration request] A floating type consisting of a box-shaped reinforcing material filled with brittle fracture material, an upper block that can be equipped with a low-reaction force elastic body on the front, and a lower block that is mainly formed of a plastically deformable body. In the shock absorber, the crushing strength of the collision surface of the upper block is smaller than the strength of the colliding ship, and a rigid mounting body floating around the outer periphery of the underwater structure is provided between the underwater structure and the upper and lower blocks. A shock absorbing device characterized in that the upper and lower blocks are removably but fixedly attached to a rigid mounting body.