JP2014101663A - Gravity-type breakwater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gravity-type breakwater with a tenacious constitution, which, while being relatively simple in the constitution, does not instantly lose the entire function even when it suffers a load caused by an unexpected great energy caused by a tsunami or the like.SOLUTION: A gravity-type breakwater in this invention comprises: a heavy construction 4 which is set as a breakwater on a mound 3 built on a foundation 2; a vertically-standing support structure body 5 which is installed in a non-continuing state from the heavy construction 4 at least at a position away from the heavy construction 4 on either the front side or the back side of the heavy construction 4; and a filling material which is filled between the heavy construction 4 and the support structure body 5 to transfer a horizontal force caused by the aforesaid heavy construction 4 to the support structure body 5. The aforesaid support structure body 5 is piled into the foundation 2 with its top end protruding above the mound 3 on which the aforesaid heavy construction 4 is placed, while the aforesaid filling material 6 is filled in a space between a protruding part 5a of the support structure body 5 and the heavy construction 4.

Description

  The present invention relates to a gravity breakwater formed by a caisson made of concrete, for example, and more particularly to a gravity breakwater having a structure that is tough against waves having large energy such as a tsunami.

  A breakwater using a concrete caisson, widely known as a gravity breakwater, is a structure that resists loads acting on energy such as waves by filling the caisson with gravel and water. In general, stabilization is achieved by the frictional force generated between the ground where the caisson is installed and the mound built on the ground due to the gravity.

By the way, the gravitational breakwaters as described above are usually used for loads associated with energy such as waves (including storm surges) caused by typhoons and developed low pressures, or tsunamis caused by earthquakes, which are likely to occur during the service period. Is designed to be safe.
However, when a load with energy more than expected is applied, sliding failure may occur due to insufficient frictional force between the caisson and the ground or mound.
In fact, in the Great East Japan Earthquake that occurred in 2011, a tsunami larger than expected was generated, and a load exceeding the expected level was applied to the caisson. As a result, the breakwater function was destroyed to the point where it was lost in an instant, resulting in enormous damage, and the function of the breakwater could not be guaranteed at all.

  For this reason, when a load associated with energy such as tsunami assumed in the conventional design is applied, even if a certain amount of damage is caused, avoid breakage that suddenly loses the function as a breakwater, and slightly enhance the function of the breakwater However, there is a demand for a persistent breakwater structure that can be maintained.

Accordingly, as shown in FIG. 11, in the gravity type breakwater 11, a backfill stone is placed on the rear surface side (inside of the harbor) of a heavy structure 14 such as a caisson disposed on a mound 13 formed on the ground 12. A reinforcing structure 15 for reinforcing a breakwater has been proposed in which a reinforcing base 15 formed in an inclined surface shape is stacked to thereby suppress the movement of the heavy structure 14.
However, according to this reinforcing structure, although it can resist a larger load depending on the weight of the reinforcing table 15, the type of failure in the case of the breakwater 11 having this reinforcing structure is represented by sliding failure. Once destruction begins, it becomes destruction that loses function in an instant. That is, when a heavy load is applied to the heavy structure by a tsunami or the like and the reinforcement base that should receive this load is broken without being able to withstand the load, the heavy structure slides and is swept away at once, Because it loses its function instantly, it is hard to say that it has a tenacious structure.
In addition, the method of stacking backfill stones inside the port to form the reinforcement stand 15 reduces the effective area in the port and also changes the water depth in each place, thus drastically changing the operation in the port. There is a high possibility that the necessity will arise, and there is a possibility that problems such as many restrictions will occur in the utilization of port facilities.

Moreover, as a proposal of a tenacious structure, the method of utilizing the steel building materials which have high toughness, such as a steel pipe pile and a steel sheet pile other than the above-mentioned thing exists.
For example, Patent Document 1 describes a revetment structure in which a cell is formed using a steel pipe sheet pile or the like, and a filling soil is filled in the cell. The technique of Patent Document 1 cannot be applied to the structure of a heavyweight breakwater using caisson, which can realize a very useful and tenacious structure when a structure related to a revetment structure is newly constructed.

Patent Document 2 describes a revetment structure in which a wall-like structure composed of a steel sheet pile or a steel pipe sheet pile is placed on the front side and the rear side of a caisson, and the wall-like structure is connected to the caisson. Yes.
However, this revetment structure has no problem in terms of structural stability, but because the wall structure and caisson are connected, the construction of this point is complicated and the installation work becomes very troublesome, and the installation cost Has the disadvantage of rising. In addition, since the technology of Patent Document 2 is a revetment structure, the front side of the caisson is the sea or river while the rear side is land, the installation work is accessed from the land on the revetment side. Therefore, simplification of installation work is not essential. On the other hand, in the case of a breakwater that is installed in the sea area between both sides of the front side and the rear side, the installation work is very large and difficult in the first place compared to the case of the above revetment structure. The construction of connecting the caisson and the wall-like structure is very burdensome both in terms of labor and cost. Therefore, there is a great need from the engineer for a technology that can guarantee the performance without such connection work.
In addition, the technology of Patent Document 2 is used for a seawall where the front side of the caisson is the sea or river and the rear side is a land, and both the front side and the back side have a tenacious structure with the breakwater facing the sea. Since this basic idea is completely different, this technology cannot be used as it is for breakwaters.

JP 2003-253644 A Japanese Patent Laid-Open No. 9-13343

  The technical problem of the present invention is a gravitational type having a tenacious structure that does not lose all functions in an instant even if a load accompanying a large energy such as an unexpected tsunami acts while having a relatively simple structure The purpose is to provide a breakwater.

  In view of the above, as a result of earnest research to find a tenacious structure in a breakwater equipped with a heavy structure such as caisson, the present inventors have found that steel sheet piles that have been placed on the ground on the front side and the rear side of the heavy structure, It has been found that it is effective to support the structure by a support structure such as a steel pipe sheet pile so that the support structure receives a horizontal force from the heavy structure.

  On the other hand, as shown in FIG. 12, a support structure 24 that supports the weight structure 23 is placed on the upper end side of the weight structure 23 that is placed on the mound 22 formed on the ground 21. Projecting from the mound 22 and placing the projecting portion 21a in direct contact with the heavy structure 23, the influence of the change in the ground properties accompanying the placement of the support structure 24 There is a risk that the heavy structure 23 is received, the ground 21 and the mound 22 are loosened, and the installation of the heavy structure 23 becomes unstable or easily slid. In addition, in order to prevent such a situation, a certain amount of work is required, and thus the construction work during installation may be complicated.

Further, when the support structure 24 is in direct contact with the heavy structure 23, as shown in FIG. 13, the heavy structure is caused by a load accompanying the energy such as a tsunami (open arrow in the figure). When 23 moves in the direction of the support structure 24, the support structure 24 that has received the force from the weight structure 23 is pushed by the weight structure 23 and becomes convex in the direction of the weight structure 23. An elastic deformation that curves like this occurs.
At this time, in the protruding portion 24 a of the support structure 24, the protruding portion 24 a presses a part of the mound 22 and the ground 21 on the back side to destroy the portion. Further, in the embedded portion of the support structure 24, due to elastic deformation of the support structure 24, the strength is reduced by releasing the restraining pressure in the vicinity of the support structure 24, that is, in the ground 21 and the mound 22 immediately below the heavy structure 23. As a result, it has been found by the inventors' analysis that the heavy structure 23 slides or sinks.

  In order to solve this problem, as a result of further studies by the inventors, the support structure is separated from the weight structure, and gravel, crushed stone, etc. are provided between the support structure and the weight structure. It has been found that it is effective to fill the filler in the horizontal direction and indirectly transmit and receive the horizontal force from the heavy structure to the support structure through the filler. The inventors have found that the problems associated with the placement of the support structure and the elastic deformation of the support structure can be solved while sufficiently supporting the heavy structure, and the present invention has been completed.

  That is, in order to solve the above-described problem, the gravity breakwater of the present invention includes a heavyweight structure for wave protection disposed on the ground or a mound provided on the ground, and a front side of the heavyweight structure. At least one of the rear surface side and the weight structure is spaced apart from the weight structure, the support structure is disposed in a non-connected state with the weight structure, and the weight structure and the support. And a filler that fills the structure and transmits horizontal force from the heavy structure to the support structure, and the support structure protrudes upward from the ground or mound. And the filler is filled in the space between the projecting portion of the support structure and the weight structure, and is transmitted from the filler to the support structure. The horizontal force from the heavy structure is received. Te is characterized in that to support the heavy weight structure.

In the present invention, the height of the protruding portion from the ground or mound in the support structure is lower than the height in the vertical direction of the heavy structure in a state of being disposed on the ground or mound. Can do.
In the present invention, the heavy structure is disposed on a mound having a height H provided on the ground, and the support structure is formed from the height of the bottom surface of the heavy structure. When the distance in the depth direction to the tip of the body is D, the distance L from the opposing surface of the heavy structure is disposed at a position in the range of 2H ≦ L ≦ D / 2. It is preferable.

According to the present invention, the support structure that receives the force in the horizontal direction from the heavy structure and supports the heavy structure is arranged apart from the heavy structure without being connected to the heavy structure, and these support structures. By filling the space between the heavy structure and the filler, the horizontal force from the heavy structure is received and the destruction is suppressed as much as possible. On the other hand, even if a force from the heavy structure acts on the support structure, the influence of the support structure during placement or loosening of the ground and mound due to elastic deformation of the support structure is minimized. Therefore, the sliding and sinking of the heavy structure due to the placement of the support structure and the elastic deformation can be suppressed.
As a result, even if a load accompanying large energy such as an unexpected tsunami acts and the heavy structure moves, the supporting structure and the filling material cause the complete breakwater due to sliding or sinking of the heavy structure. Therefore, it is possible to obtain a gravitational breakwater with a tenacious structure that prevents any breakage and loses all breakwater functions in an instant.

It is sectional drawing which shows typically one Embodiment of the gravity type breakwater which concerns on this invention. It is the same top view. It is a schematic diagram for demonstrating the load dispersion | distribution of the load of a horizontal direction. However, the case where the separation distance from the heavy structure in the support structure is small is shown. It is a schematic diagram for demonstrating the load dispersion | distribution of the load of a horizontal direction similarly. However, the case where the separation distance from the heavy structure in the support structure is large is shown. It is a schematic diagram for demonstrating load distribution of the load by the stress of the lower surface side of a heavy structure. It is a schematic diagram for demonstrating the load dispersion | distribution of the load by the stress of the lower surface side of a heavy structure similarly. However, the case where the rooting length of the support structure is small is shown. It is sectional drawing which shows typically embodiment different from FIG. 1 of the gravity type breakwater which concerns on this invention. It is sectional drawing which shows typically further another embodiment of the gravity-type breakwater which concerns on this invention. It is sectional drawing which shows typically the state which overfilled in the gravity type breakwater which concerns on this invention. It is a graph which shows the result of an Example. However, the vertical axis represents the magnitude of the applied load (load / caisson weight) per unit weight of the heavy structure (caisson), and the horizontal axis represents the horizontal displacement of the heavy structure (horizontal displacement). Respectively. It is sectional drawing which shows typically an example of the reinforcement structure of the conventional weight type breakwater. It is sectional drawing which shows typically the case where a support structure is laid in the state which contacted the heavy structure when reinforcing a heavy weight type breakwater. In the structure of FIG. 12, it is sectional drawing explaining the state which the load acted on the heavy structure.

1 and 2 show an embodiment of a gravity breakwater according to the present invention. A breakwater 1 according to this embodiment is disposed on a mound 3 formed on a ground 2 in the sea. A weight-proof structure 4 for preventing waves, a support structure 5 extending in a vertical direction and disposed on the rear surface side of the weight structure 4 in an unconnected state, and these weight structures 4 and the support structure 5 are provided.
In the present invention, the front side of the heavy structure is basically the direction opposite to the land (in the case of a port, the outside of the port), and the rear side of the heavy structure is basically the land. It points to the opposite direction (in the case of a port, the inner side of the port). Moreover, the breakwater in this invention points out the thing by which the front side and rear surface side of a heavyweight structure face the sea, and also contains what is called a wave breakwater notionally.

The weight structure 4 is, for example, a caisson formed in a concrete box shape and filled with crushed stone or the like, or a stacked block formed of concrete. It resists by receiving the received load.
In this embodiment, a concrete caisson formed in a substantially rectangular parallelepiped shape is used, and is placed on the mound 3 with a part of the upper end side protruding upward from the sea surface S. Furthermore, as shown in FIG. 2, the breakwater 1 has a configuration in which a plurality of caissons as the heavy structure 4 are arranged side by side in a state of being spaced apart by a certain distance.
Further, the mound 3 is formed by pulverizing stones or the like up to a predetermined height on the ground 2 in the sea, and the upper end portion is a flat surface on which the heavy structure is stably placed. Be able to.

The support structure 5 has a function of receiving the horizontal force from the heavy structure 4 and supporting the heavy structure 4. In this embodiment, a plurality of steel pipe piles are connected to various joints or A series of wall-like structures formed by connecting each other with steel plates or the like, and as shown in FIG. 2, are extended over the entire length of the breakwater along the longitudinal direction of the breakwater. It has become a thing.
In the case of this embodiment, a gap is formed between the adjacent heavy structures 4, 4, but the support structure 5 is formed in series as a whole without being interrupted by the gap portion. ing.
The support structure 5 is placed on the ground 2 in a state of penetrating the mound 3 at a position separated from the weight structure 4, more specifically, a rear surface of the weight structure 4 by a certain distance. Has been.
Further, the support structure 5 is placed on the ground 2 in a state where a part of the upper end side protrudes upward from the upper surface of the mound 3, and the filler 6 protrudes from the support structure 5. The space between the portion 5a and the rear surface side of the heavy structure 4 is filled. Therefore, in this embodiment, the height of the protruding portion 5a in the support structure 5 is substantially the thickness of the filler 6 (height in the vertical direction).
The support structure 5 is not connected to the heavy structure 4 or the filler 6, and the heavy structure such that the upper end side is pressed from the heavy structure 4 or the filler 6. 4 and the filler 6 are not directly pressed downward.

The filler 6 transmits a horizontal force from the heavy structure 4 to the support structure 5, and therefore the support structure 5 is actually indirect via the filler 6. Thus, the horizontal force from the heavy structure 4 is transmitted, and the heavy structure 4 is supported by receiving the force.
The filler 6 includes gravel, crushed stone, and the like, and is filled in an upper opening space surrounded by the support structure 5 and the heavy structure 4 on the mound 3. In the case of this embodiment, the filler 6 is basically arranged in series along the support structure 5, and there is a gap between adjacent weight structures 4, 4 in the weight structure 4. It is the aspect with which it filled also with the part in which this is formed.
Further, the filler 6 is only filled between the support structure 5 and the heavy structure 4, and the support structure 5 and the heavy structure 4 are not fixedly connected to each other. No.

The filler 6 includes gravel and crushed stone as described above. As a specific configuration of the filler 6, the crushed stone or the like is formed on the upper end surface of a layer formed of crushed stone or the like. It is desirable that a covering block is provided so as not to fly up.
In this case, the layer formed of crushed stone or the like is formed such that the upper end surface thereof is lower than the height of the upper end of the support structure by the thickness of the covering block. By placing the covering block on the upper end surface, the filler is formed.

By the way, the support structure 5 is driven at a position separated from the heavy structure 4 as described above. The reason why the support structure 5 is separated from the weight structure 4 is as follows.
That is, as described above, when a part of the upper end side of the support structure is protruded from the mound and the protruding part is placed in direct contact with the heavy structure, the support structure There is a high possibility that the heavy structure itself will receive changes in the ground properties accompanying the body placement. If so, there is a risk that the ground and mound will loosen and the installation of heavy structures will become unstable, and it will be easier to slide, and it will be necessary to perform construction to take some measures to prevent this There is a problem that the installation work becomes complicated.

More seriously, when the support structure is in direct contact with the heavy structure as shown in FIG. 7, when the heavy structure moves in the direction of the support structure, The support structure that has received the force is pushed from the heavy structure and causes elastic deformation in a direction away from the heavy structure (right side in FIG. 7) as shown in FIG. The impact on the ground and mound is extremely large.
That is, when the support structure is elastically deformed by a force from the heavy structure, the protruding portion of the support structure has a back side (a surface opposite to the contact side with the heavy structure). Since the mound part is pressed with a large force at the side), the pressed part of the mound is destroyed.
On the other hand, when the upper end side of the support structure is pushed away from the heavy structure by the heavy structure, the support structure as a whole protrudes in the direction of the heavy structure (left side in FIG. 7). Elastic deformation is generated. Therefore, in the portion where the support structure is embedded in the ground or mound, the ground or mound on the heavy structure side is pressed by this elastic deformation of the support structure. Then, in the ground or mound located on the side of the heavy structure of the support structure that is in contact with or close to the support structure, shear pressure is generated by the pressing force, which causes a decrease in strength or slip failure due to release of the restraint pressure. It is.
As a result, the heavy structure slides and sinks due to the destruction of the ground and mound, so if an unexpectedly large load such as a tsunami continues to act on the heavy structure, It collapses in a short time, and after the collapse, there is a very high possibility of losing the wave protection function in an instant.

  For this reason, in the present invention, the support structure is intentionally separated from the heavy structure, so that the destruction of the ground and the mound due to the elastic deformation of the support structure is suppressed as much as possible. On the other hand, the filler is filled between the support structure and the heavy structure which are separated from each other, and the horizontal force from the heavy structure is indirectly applied to the support structure through the filler. By making it possible to transmit, the support structure can reliably receive the force from the heavy structure so that the heavy structure can be supported.

Further, the separation distance between the support structure 5 and the heavy structure 4 is specifically determined as follows.
That is, the height of the mound 3 on which the heavy structure 4 is placed is H, and the distance in the depth direction from the height of the bottom surface of the heavy structure 4 to the tip of the support structure 5 (in this embodiment) In the case where D is the length of the support structure 5 to the ground including the mound 3), from the opposing surface of the weight structure 4 in the support structure 5 (in this case, the rear surface of the weight structure 4). Is determined so as to be within a range of 2H ≦ L ≦ D / 2.
Hereinafter, the reason why the range of the separation distance L is determined to be such a range will be described in detail.

As shown in FIGS. 3 and 4, when a very large load is applied from the front side of the heavy structure 4, the heavy structure 4 pushes the filler 6 in an attempt to move to the rear side. Is transmitted to the projecting portion 5 a from the mound 3 in the support structure 5 through the filler 6.
At this time, when the filler 6 and the mound 3 have a sufficient height, the support structure 5 is separated from the heavy structure 4, so that the load from the heavy structure 4 is dispersed in the mound 3. Then communicate. Therefore, the load that is actually transmitted to the protruding portion 5 a of the support structure 5 through the filler 6 is smaller than the load output from the heavy structure 4 toward the filler 6.
Here, it is assumed that the load is distributed at a dispersion angle α with a gradient of 1/2, although a plurality of factors such as the influence of the physical properties of the ground 2 and the mound 3 affect the transmission of the load. Is common.

Therefore, the present inventors have intensively studied to find a separation distance that can maximize the effect of such load distribution.
As a result, as shown in FIG. 3, when the support structure 5 is disposed close to the heavy structure 4 in a non-contact state, load dispersion from the heavy structure 4 occurs in the mound 3. since the range of the pressure receiving surface a ₁ is small for receiving the dispersed load in the support structure 5, the effect of load distribution that can be enjoyed by the support structure 5 was found to be less likely than the much larger. That is, since the load acts as a high pressure in a relatively narrow range and concentrates on the upper end side of the support structure 5, it does not tend to be favorable from the viewpoint of stability of the support structure, such as causing a large deformation.
Therefore, it has been found that a large load still acts on the protruding portion 5a of the support structure 5 from the mound 3 as compared with the case where the support structure 5 is in contact with the heavy structure 4.
On the other hand, as shown in FIG. 4, when the separation distance between the support structure 5 and the heavy structure 4 is large, the range of the pressure receiving surface A ₂ that receives the dispersed load in the support structure 5 becomes large. It is possible to sufficiently obtain the effect of the above and to reduce the acting pressure. However, when the separation distance between the support structure 5 and the heavy structure 4 becomes too large and the extension line m of the dispersion angle α reaches the ground 2, load distribution is effectively performed in the ground 2 portion. I knew it was n’t there.
This is crushed stone or the like in which the filler 6 and the mound 3 are artificially formed and installed, whereas the local board 2 which is a soil structure made of materials such as sand and clay is relatively soft and can transmit load. Is considered to be because it is difficult to contribute.

As a result, the load distribution for the horizontal load generated when the weight structure 4 pushes the filler is performed exclusively in the filler 6 and the mound 3, which are relatively hard materials. It has been found that the pressure-receiving surface of the support structure 5 with respect to the load related to is likely to be a portion corresponding to the height of the filler 6 or the mound 3 at the maximum.
Therefore, in order to maximize the effect of load distribution, the pressure receiving surface of the support structure 5 is set to a range corresponding to the height of the filler 6 and the mound 3. It became clear that it was important to specify the separation distance.

From the above results, the distance L from the weight structure 4 is equal to the height H of the mound from the viewpoint of maximizing the effect of load distribution on the horizontal force from the weight structure 4. In the relationship, it came to the conclusion that it is desirable to set it as the range of L> = 2H at least.
In addition, about the said separation distance L, even if it exceeds this range, it is difficult to enjoy the effect of load distribution further, but conversely, it is thought that the effect of load distribution itself is not lost.

On the other hand, when a load caused by a tsunami or the like is applied to the heavy structure 4, the heavy structure 4 is generated due to rotation of the heavy structure 4 due to the horizontal load or due to the weight of the heavy structure 4. The stress on the lower surface side is transmitted through the mound 3 and the ground 2 under the heavy structure 4.
In general, it is known that the fracture strength of ground materials increases due to restraint pressure. From this viewpoint, restraint effect is exhibited by suppressing the deformation of the ground in the range of stress action due to the weight of the heavy structure. As a result, the strength is improved. That is, as shown in FIG. 5, in the stress transmission in this case as well, the restraint pressure F is generated on the mound 3 and the ground 2 by utilizing the effect of load distribution, and the strength of the mound 3 and the ground 2 is increased. Is possible.
Here, the strength of the general ground or mound is greatly affected by the restraining pressure of the material forming the ground or the mound or the restraining effect due to its own weight, but the support structure 5 has the ground 2 and the mound 3 depending on its rigidity. It is known that a constraining effect is imparted to these materials and contributes to an increase in the strength of the ground 2 and the mound 3. However, if the support structure 5 is improperly arranged or deeply embedded, the restraining effect in the range in which stress is transmitted from the lower surface of the heavy structure cannot be expected, and the effect of increasing the strength of the ground or the mound is weak. .

For example, as shown in FIG. 6, when the root length of the support structure 5 is small, the dispersion angle β at the time of load dispersion (in this case, the dispersion angle β is a gradient 1/2 (hence front view). In this case, it is considered that the gradient 2) does not intersect the support structure. Then, it was found that the ground or mound that receives stress transmission from the lower surface of the heavy structure is less susceptible to the restraining effect of the support structure.
Moreover, when the separation distance from the heavy structure 4 of the support structure 5 is too large, it is not easily affected by restraint restraint by the support structure, and the distributed load transmission range does not reach the support structure. There is a possibility that the effect of strength increase by the restraining effect cannot be enjoyed.

Thereby, in order to effectively obtain the restraining effect of the ground 2 or the mound 3 by the stress transmission from the lower surface of the heavy structure 4 by the support structure 5, at least the extension line n of the dispersion angle β at the time of load distribution is It has been found that it is necessary to cross the support structure 5.
As a result, in terms of stress transmission from the lower surface of the weight structure 4, the weight of the support structure 5 can be effectively used from the viewpoint of effectively using the effect of load dispersion and enjoying the restraining effect of the ground 2 or the mound 3. The distance L from the structure 4 is at least in the range of L ≦ D / 2 in relation to the distance D in the depth direction from the height of the bottom surface of the heavy structure 4 to the tip of the support structure 5. I came to the conclusion that this is desirable.

As described above, with respect to the separation distance from the weight structure 4 in the support structure 5, the viewpoint of maximizing the effect of load distribution on the horizontal force from the weight structure 4, and the weight structure As a result of comprehensive consideration of the viewpoint of obtaining the restraining effect of the ground 2 or the mound 3 by effectively using the effect of load dispersion in the stress transmission from the lower surface of the base plate 4, the separation distance L is 2H ≦ L ≦ D / It can be seen that it is desirable to be within the range of 2.
Therefore, in this embodiment, the separation distance L from the rear surface of the weight structure 4 of the support structure 5 is determined so as to be within the range of 2H ≦ L ≦ D / 2. Even when the heavy structure 4 receives an unexpectedly large load due to the wave of energy, the structure of the breakwater can be realized more effectively by effectively utilizing the effect of load distribution.

The height of the protruding portion 5a protruding from the mound 3 in the support structure 5, that is, the height of the upper end of the placed support structure 5 is the height of the heavy structure 4 placed on the mound 3. It is lower than this. In the case of what is shown in FIG. 1, the protruding height of the protruding portion 5a of the support structure 5 is not more than half of the height of the heavy structure 4, and therefore the support structure 5 and the filler 6 are both underwater as a whole. It is in the state located in.
As described above, the projecting height of the projecting portion 5a of the support structure 5 is lower than the height of the weight structure 4 placed on the mound 3 because the support structure is mainly formed from the weight structure. This is because a structure that can support the horizontal load and obtain the effect of suppressing horizontal displacement such as sliding of the heavy structure and that can ensure at least the effect is sufficient. Further, the protruding height of the protruding portion 5a of the support structure 5 may be higher than the height of the center of gravity of the heavy structure or the center of gravity of a distributed load such as a load from a wave, but from the viewpoint of cost. This is because it is required to be as low as possible within a range in which the effect of suppressing the horizontal displacement of the heavy structure can be secured.
However, as described above, since the height of the protruding portion 5a in the support structure 5 substantially corresponds to the thickness of the filler 6, at least the filler 6 is in the horizontal direction from the heavy structure 4. It is important to set the height of the upper end of the support structure 5 so as to ensure a protrusion amount capable of imparting a strength that can transmit the force of the power to the support structure 5 reliably and stably. .

In constructing a breakwater having the above-described structure, first, a mound 3 having a predetermined height is formed on the ground 2, and a heavy structure 4 is placed and disposed on the mound 3.
The mound 3 and the heavy structure 4 at this time may be newly established, but may be an existing mound and heavy structure. Therefore, the already built breakwater mound and heavy structure are used. can do.

Thereafter, the support structure 5 is not connected to the weight structure 4 at a position separated from the weight structure 4 on the rear surface side of the weight structure 4 and the weight structure 4 is disposed. In the state where the upper end side protrudes upward from the mound 3, the ground 2 is driven in the vertical direction.
In this case, the support structure 5 is such that the height of the protruding portion 5a protruding from the mound 3 in the support structure 5 is in the vertical direction of the weight structure 4 in a state of being disposed on the mound 3. It is preferable to place it so that it is lower than the height.
Further, the support structure 5 has a mound height of H and a distance D in the depth direction from the height of the bottom surface of the weight structure 4 in the support structure 5 to the tip of the support structure 5. The distance L from the rear surface of the heavy structure 4 is preferably disposed at a position where 2H ≦ L ≦ D / 2.

  Finally, the filler 6 is filled by, for example, putting crushed stone or the like as the material of the filler 6 into the space between the protruding portion 5a of the support structure 5 and the heavy structure 4. Thus, the breakwater 1 having a tenacious structure is completed.

Thus, according to the breakwater 1 having the above-described configuration, the support structure 5 that supports the heavy structure 4 by receiving the horizontal force from the heavy structure 4 is coupled to the heavy structure 4. The support structure 5 is arranged in a horizontal direction from the weight structure 4 by being arranged in a state of being spaced apart and filled with a filler 6 in the space between the support structure 5 and the weight structure 4. Since the force is received, the breakage of the breakwater 1 due to the sliding of the heavy structure 4 or the like can be suppressed as much as possible.
On the other hand, since the support structure 5 is provided at a position separated from the heavy structure 4, the ground structure 2 and the mound 3 immediately below the heavy structure 4 are changed by the placement of the support structure 5. Giving is suppressed. And even if the force from the heavy structure 4 acts on the support structure 5 and this support structure 5 deform | transforms, it can suppress that the ground 2 and the mound 3 are destroyed by the deformation | transformation. Therefore, the sliding and sinking of the heavy structure 2 due to the influence of the placement and elastic deformation of the support structure 5 on the ground 2 and the mound 3 can be suppressed.
As a result, even if a load accompanying large energy such as an unexpected tsunami acts on the heavy structure 4 and the heavy structure 4 moves due to the load, the breakwater caused by sliding or sinking of the heavy structure Since complete destruction is suppressed, it is possible to obtain a gravitational breakwater with a tenacious structure that does not lose all the breakwater functions in an instant.
In addition, it is not necessary to connect the heavy structure 4, the support structure 5, and the filler 6 to each other, and the overall structure is relatively simple. Therefore, there is an advantage that the labor of construction work can be saved and the construction cost can be reduced accordingly.

In the above embodiment, the support structure 5 and the filler 6 are disposed only on the rear surface side of the heavy structure 4. However, the support structure may be disposed on the front surface side of the heavy structure. .
Furthermore, as shown in FIG. 7, the support structure and the filler may be disposed on both the front side and the back side of the heavy structure. As described above, when the support structure and the filler are provided on both the front side and the rear side of the heavy structure, the effect of the present invention is exhibited even in the case of a tsunami or the like. Is very useful.
Moreover, in the said embodiment, although the said support structure 5 is laid in the ground 2 in the state which penetrated the mound 3, as shown in FIG. 8, a support structure is directly on the ground outside a mound. In addition, about each structure of the ground structure and mound in FIG.7 and FIG.8, and the heavy structure which forms a gravity-type breakwater, a support structure, and a filler, it is fundamentally carried out in the said implementation. Since it is substantially the same as a form and has the same effect, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  Furthermore, in the above-described embodiment, the heavy structure 4 is placed on the mound 3 formed on the ground 2, but depending on various conditions such as the shape of the ground surface and the ground properties, the heavy structure is on the ground. You may make it mount directly.

In the above embodiment, the distance L from the heavy structure 4 in the support structure 5 is the height H of the mound, the distance D in the depth direction from the height of the bottom surface of the heavy structure to the tip of the support structure. However, if the support structure can be disposed in a state of being separated from the heavy structure, the separation distance is not necessarily limited to such a distance. It is not necessary to determine within the range, and can be arbitrarily determined according to the situation.
Moreover, about the height of the protrusion part 5a which protruded from the ground 2 or the mound 3 in the said support structure 5, like the said embodiment, the said heavy structure in the state arrange | positioned on the ground or a mound The height does not need to be less than half of the height in the vertical direction, and does not necessarily need to be lower than the height in the vertical direction of the heavy structure, and can be set appropriately.
Further, when placing the support structure 5 on the ground 2, unlike a normal steel pipe pile or the like, it is not always necessary to root the lower end side of the support structure up to the support layer of the ground, and the depth of penetration Alternatively, the amount of penetration can be arbitrarily set within a range that does not hinder, according to various conditions such as the surrounding environment.

  Moreover, in the said embodiment, although the support structure 5 is made into the thing of the structure which mutually connected the some steel pipe pile using various joints or a steel plate etc., and formed it in the wall shape as a whole, for example, a steel sheet pile etc. The structure formed in wall shape using may be sufficient. Alternatively, as this support structure, a plurality of steel pipe piles are driven at regular intervals to form a comb-like form in which a space is formed between adjacent steel pipe piles, and seawater flows through the space between these steel pipes. It is good also as a structure which can distribute | circulate.

In the said embodiment, although the example containing crushed stone etc. was shown as a material of the filler 6, as the material of this filler, the horizontal direction force from the said heavy weight structure is underwater in the said support structure. Any material can be used, for example, a concrete block formed to fit the size of the space between the heavy structure and the support structure.
Furthermore, in the said embodiment, although the thickness (height of a perpendicular direction) of the filler 6 is made substantially the same as the height of the protrusion part 5a in the said support structure 5, the thickness of a filler is the same. The height is not necessarily the same as the height of the protruding portion of the support structure. For example, the thickness of the filler is set within a range in which the filler can secure a strength sufficient to reliably and stably transmit the horizontal force from the heavy structure to the support structure. You may make it lower than the height of a protrusion part. In this case, there is an advantage that outflow of crushed stone or the like which is the material of the filler is suppressed.
In addition, as shown in FIG. 9, the filler is also reinforced with gravel, crushed stone, soil, etc., as shown in FIG. The filler may be prevented from flowing out. However, it is important that the surplus is performed within a range that does not affect the operation within the port as much as possible. In addition, about each structure of the ground structure and mound in FIG. 9, and the weight structure which forms a gravity type breakwater, a support structure, and a filler, it is substantially the same as the said embodiment fundamentally, Moreover, in order to show the same effect, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

In order to confirm the effect of the gravitational breakwater according to the present invention, an experiment was conducted to analyze and compare the ground and mound failure status of the breakwater having the structure of the present invention and the breakwater not having the structure of the present invention. It was.
Specifically, in this experiment, a weight structure (height 19 m, depth 18 m, width 1.0 m) placed on a 3 m-high mound is spaced 4.5 m from the rear surface of the weight structure. The structure in which the support structure is disposed at the position and the filler is filled between the heavy structure and the support structure (hereinafter referred to as the present invention example 1), and the support structure at a position spaced 9.0 m away. And a structure in which a filler is filled between the heavy structure and the support structure (hereinafter referred to as the present invention example 2), and the upper end side of the support structure (from the mound). For the structure in which the projecting portion of FIG. 12 is in direct contact (that is, the structure in FIG. 12, hereinafter referred to as Comparative Example 1), and the unreinforced structure without the support structure (Comparative Example 2). Apply a horizontal load to the front side of the plate and gradually increase the load. . And it evaluated whether it was a tenacious structure.

In the above experiments, Examples 1 and 2 and Comparative Examples 1 and 2 used heavy structures, mounds, and support structures having the same shape and the same material as each other. . In Examples 1 and 2, the material of the filler was the same.
In the present invention examples 1 and 2 and comparative example 1, the support structure has a height of 26 m which is formed by connecting a plurality of steel pipe sheet piles (φ1000 mm) and steel plates (plate thickness 16 mm) to form a wall shape. , And placed on the ground so that the upper end side protrudes 1 m from the mound.
Note that the separation distance of the support structure from the heavy structure in Examples 1 and 2 of the present invention is the distance between the rear surface of the heavy structure and the front surface of the support structure (the surface facing the heavy structure).
Furthermore, for each example, by examining the relationship between the magnitude of the load acting on the unit weight of the heavy structure (caisson) and the horizontal displacement (front-rear direction) of the heavy structure according to the load The resistance to the load and the tenacity were evaluated.
The results are shown in FIG.

As shown in FIG. 7, when the present invention examples 1 and 2 are compared with the comparative examples 1 and 2, the present invention examples 1 and 2 endure a larger load than the comparative examples 1 and 2 at the same displacement. From the above, it can be seen that the inventive examples 1 and 2 exhibit a greater resistance than the comparative example. Note that Comparative Example 2 was poor in resistance compared to Comparative Example 1, and slipped when a load exceeding a certain level was applied, and the resistance did not increase.
In addition, the first and second embodiments of the present invention are capable of enduring a large load tenaciously because even if the applied load increases, the breakwater does not break and the displacement increases following the increase in the load. You can see that
Thus, it can be said that Examples 1 and 2 of the present invention can endure very persistently while having a higher level of resistance than Comparative Examples 1 and 2.
Therefore, according to the present invention, it has been proved that a tenacious configuration can be realized without losing all functions in an instant even when a large load is applied.

In comparison with Invention Examples 1 and 2, Invention Example 2 having a larger separation distance had higher opposing force and tenacity than Invention Example 1.
This is because Example 2 of the present invention has a larger separation distance than Example 1 of the present invention, and a sufficient dispersion effect is obtained when the load is transmitted in the horizontal direction. Actually, since the separation distance is 9 m with respect to the mound height of 3 m, the separation distance L from the heavy structure in the support structure is the above-described desirable separation distance condition in relation to the height H of the mound. L ≧ 2H is satisfied.
On the other hand, the first example of the present invention has a relatively short separation distance and cannot obtain a large dispersion effect as compared with the second example of the present invention, and is relatively on the upper end (head) side of the support structure (steel pipe sheet pile). Due to the concentrated load acting, the amount of deformation is large.
Actually, the separation distance of 4.5 m with respect to the mound height of 3 m is that the separation distance L from the heavy structure in the support structure is related to the desired separation distance condition L described above in relation to the height H of the mound. ≧ 2H is not satisfied.

1 Breakwater 2 Ground 3 Mound 4 Heavy Structure 5 Support Structure 6 Filler

Claims (3)

A weight-proof weight structure disposed on the ground or a mound provided on the ground, and spaced from the weight structure on at least one of the front side and the rear side of the weight structure A vertically extending support structure disposed in a position disengaged from the heavy structure at a position;
A filler that is filled between the weight structure and the support structure, and that transmits a horizontal force from the weight structure to the support structure;
The support structure is placed on the ground with the upper end projecting upward from the ground or mound, and the filler fills the space between the projecting portion of the support structure and the heavy structure. Have been
A gravitational breakwater characterized in that the weight structure is supported by causing the support structure to receive a horizontal force from the weight structure transmitted from the filler.   2. The height of the protruding portion from the ground or mound in the support structure is lower than the height in the vertical direction of the heavy structure in a state of being disposed on the ground or mound. The described gravity breakwater.   The heavy structure is disposed on a mound having a height H provided on the ground, and the support structure has a depth from the height of the bottom surface of the heavy structure to the tip of the support structure. The distance L from the opposing surface of the heavy structure is disposed at a position in a range of 2H ≦ L ≦ D / 2, where D is a direction distance. The gravity type breakwater according to claim 1 or claim 2.

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