JP2995713B2 - Sand pocket type harbor equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a port facility suitable for a cooling water intake facility in a nuclear power plant or a thermal power plant, and more particularly to a sand pocket type port facility capable of separating sand components from silt components and depositing them. .

[0002]

2. Description of the Related Art Port facilities are constructed for water intake facilities of nuclear power plants and thermal power plants, and a port water intake system that takes cooling water from the calm waters at the back of the port and a water intake tower built offshore. ,
There are a tunnel water intake system that takes in cooling water through a water channel tunnel, and a water intake system that combines both systems. In general, when a port water intake system is adopted, it is often required that the port be provided with a function for anchoring ships.

[0003] The function required as a cooling water intake facility is to suppress the sediment flowing into the intake pump without transmitting harmful water level fluctuations to the intake pump. In addition, when the port is used as a port by adopting the port intake system, the functions required for the anchorage of the ship include ensuring the quietness of the ship's navigation route, the berth, and the landing area for loading materials, It is necessary to prevent sediment accumulation in the interior, reduce sedimentation, and secure and maintain the water depth of the navigation channel.

There is a difference shown in FIG. 15 between a port water intake system and a tunnel water intake system adopted as water intake facilities of a power plant, based on a difference in water intake form. Based on this difference, the use of port facilities in the vicinity of the power plant is also evaluated to determine whether to use a port water intake system or a tunnel water intake system.

[0005] In the case of tunnel intake, if there is no port near the power station, port facilities for unloading materials by ships are required, and port facilities are constructed along with the construction of the power station. Considering the case where this unloading port facility is separately constructed, it is advantageous because the port type cooling water intake system can be shared. Existing port facilities 1 and 2 equipped with this port water intake system include those shown in FIGS. In this port facility, since cooling water is taken from intake channels 3 and 4 which are calm waters in the inner part of the port, the water level fluctuation (water level fluctuation) given to the intake pump 5 is prevented. There is an advantage that the inflow of sand can be reduced. Further, if the port water intake system shown in FIGS. 16 and 17 is adopted, one port can be shared as cooling water intake equipment of several power generation plants, which is economical.

[0006]

However, FIG.
And when the port equipment shown in FIG. 17 is installed and cooling water is taken in by the port water intake method, sediment flows into the port due to waves or water intake, and if left undisturbed for a long period of time, the sediment flows into the water intake pump. However, since the channel water depth cannot be secured, it is necessary to dredge the accumulated sediment. When the tunnel intake system is adopted, a sand basin is installed at the exit of the intake tunnel, etc., to remove sediment flowing into the intake pump. Therefore, dredging in the sand basin is required.

The sediment deposited in the harbor facilities 1 and 2 of the cooling water intake facility has a small particle size (approximately 75 μm or less) and a large particle size (approximately 75 μm) due to the difference in particle size.
Above) and sand. The silt component and the sand component have different sedimentation areas in the harbor.

[0008] In a general intake port, since the sand having a large particle diameter has a high sedimentation velocity, the sand rolled up by the waves flows into the port by a beach current or an intake current, and is deposited near a port entrance. Since the particles are small in particle size, they have a low sedimentation velocity, flow in with the intake flow, and tend to accumulate in a region of high calmness, for example, behind the breakwater.

In a cooling water intake system employing a tunnel intake system, a sand component mainly accumulates in a sand basin, and a silt component tends to accumulate on the wall surface side of the sand basin.

[0010] On the other hand, sand components having a large particle size out of the sediment deposited in the harbor are effective as backfill materials for construction sites and fine aggregates of concrete, and can be reused. Provided. Storage and storage of dredged soil for reuse
Processing is actively performed.

Since the silt component is fine particles having a small particle size, a high water content, and having excessive fluidity when the water content is high, it is necessary to reduce the water content by containing it in a sedimentation tank or the like in a power plant. However, even if the silt component is dehydrated, its particle size is too small, so no effective re-use destination has been found, and it is difficult to reuse it after dehydration. is the current situation. The capacity of silt components in power plants is increasing year by year.

[0012] Actually, in a harbor or a sand basin, the sand component and the silt component are not completely separated and deposited, but the sand component and the silt component are mixed and deposited. As a result, sand and silt are dredged simultaneously during maintenance dredging,
The recycling method is determined based on the content of dredged sand and silt.

Considering the future dredging plan, it is advantageous to operate the maintenance dredging of the port efficiently by separating and depositing the sand component and the silt component, and there is an operational advantage in consideration of the reuse of the sand component. Considered economic.

[0014] Comparing the construction facilities of both intake facilities, as a cooling water intake facility for a nuclear power plant or a thermal power plant,
Considering that it is shared with the power plant to be constructed in the future and used for cargo handling work, the port intake method is considered to be advantageous.However, even if the adoption of this port intake method is decided, In order to efficiently carry out maintenance dredging in the future, what kind of cooling water intake structure and what separation and accumulation structure of sand and silt components should be adopted in one port facility has become a problem.

The present invention has been made in view of the above circumstances, and separates and deposits a sand component from a silt component.
The main objective is to improve the efficiency of port maintenance dredging and to provide sand pocket-type port facilities with excellent economic efficiency.

Another object of the present invention is to mainly deposit a reusable sand component having a large particle size out of the sediment flowing into a port, and guide a silt component to an intake channel side to reduce the amount of dredging. Another object of the present invention is to provide a sand pocket type port facility which can easily plan and manage a dredging plan and reduce running costs.

Still another object of the present invention is to deposit a sand component from which a silt component has been separated in the inner part of a port, and to perform dredging of sand in a calm water area from a port, thereby improving the efficiency of dredging work.
It is an object of the present invention to provide a sand pocket type harbor facility which can facilitate efficiency.

Another object of the present invention is to provide an additional port facility that can be added to an existing power plant and that can be unloaded. Another object of the present invention is to provide a sand pocket type port facility which can be easily adjusted in timing.

[0019]

According to a first aspect of the present invention, there is provided a sand-pocket type port facility, in which a main breakwater protruding from the seawall to the seaside is provided. A sub-breakwater opposite to the submarine breakwater, a port divided by both breakwaters, and connected to the outside of the port through the port entrance, and installed inside this port so as to face the submarine breakwater and form an intake channel And a submerged dike installed at the entrance of the intake channel, separating the silt component from the sand component and guiding the silt component to the intake channel, separating the sand component from the silt component in the port. A sand pocket region to be deposited is formed.

In the sand pocket type port facility according to claim 2, in order to solve the above-mentioned problem, the submerged levee is provided across the entrance of the intake channel, and connects the submerged levee with the tip of the main breakwater. The direction of the waves is almost the same as the main wave direction, and the sand flowing from the port entrance from the port entrance to the port depth at the front side of the submerged embankment creates a sheet flow state by the wave force, and the sand flows to the sand pocket area In which a flash flow region is generated.

According to a third aspect of the present invention, in order to solve the above-mentioned problem, the main breakwater has a base portion extending from the revetment to the sea side and a wavebreak portion at the tip end mainly receiving waves. The sub-breakwater is formed between the ends of both breakwaters. The port entrance is opened so that it faces the direction crossing the main wave direction.

According to a fourth aspect of the present invention, in order to solve the above-mentioned problem, the number of shields on the front side of the submerged levee is not less than a limit shield number (0.5) in high surf. Is set to a length at which a sheet flow state occurs.

In the sand pocket type port facility according to claim 5, in order to solve the above-mentioned problem, an S-shaped or inverted S-shaped flow from the port entrance to the intake channel in the port formed by the main breakwater and the sub-breakwater. A channel is formed, and the intake flow guided through the intake channel is provided with an intake flow rate higher than the critical bottom shear force.

In order to solve the above-mentioned problems, in the sand pocket type harbor facility according to the sixth aspect, the submerged levee has a length and a main wave direction based on the sand concentration distribution on the front side of the submerged levee. Is set to obtain a concentration distribution of dense sand below the height of the submerged embankment.

According to a seventh aspect of the present invention, in order to solve the above-mentioned problem, a main breakwater protruding from the seawall to the sea side is provided, and the main breakwater and the main breakwater are spaced apart along the seawall. A built-in sub-breakwater, a harbor divided by both breakwaters and connected to the open sea through a port entrance, an inner breakwater installed in the harbor facing the sub-breakwater and defining a stay area for a ship, And a submerged embankment installed at the entrance of the night area, and a sand pocket area is formed on the back side of the port.

In the sand pocket type port facility according to claim 8, in order to solve the above-mentioned problems, at least one of the sub-breakwater, the inner breakwater, and the seawall is configured as a loading dock, while the submarine breakwater and the main breakwater are used. The direction connecting the tips almost coincides with the main wave direction, and the sea route from the port entrance to the stay area of the ship is constructed in a non-deposited sand structure.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a sand pocket type port facility according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a harbor layout diagram showing an example of a sand pocket type harbor facility according to the present invention. This sand pocket type port facility is a port facility suitable for cooling water intake facilities of nuclear power plants and thermal power plants, and this port facility is located on the shore where nuclear power plants and thermal power plants are installed, as shown in the example shown in the figure. Or may be juxtaposed adjacent to existing port facilities of existing nuclear power plants and thermal power plants.

The sand pocket type harbor equipment 10 includes a revetment 1
1 has a main breakwater 12 protruding toward the sea side, and a sub-breakwater 13 provided at an interval of, for example, 700 m to 800 m along the seawall 11 from the main breakwater 12. A port 14 is formed inside. A port 15 is formed between the ends of the breakwaters 12 and 13, and the port 14 is connected to an open sea 16 outside the port via the port 15.
The port opening 15 has an opening width of, for example, about 300 m.

The main breakwater 12 is several hundred meters from the seawall 11 to the sea side.
Base 12a extending to the extent and main breaker 12b several hundred meters long
The sub-breakwater 13 facing the main breakwater 12 is formed in a base 13
a and the sub-wavebreak part 13b following this base part 13a are formed in an inverted letter shape (or an inverted letter shape). The shape and dimensions of the main breakwater 12 and the sub breakwater 13 may be variously modified in accordance with the direction of the coast, the topography, and the like.

In the harbor 14, a dike 16 serving as an inner breakwater is installed on the side of the sub-breakwater 13 so as to face the sub-breakwater 13. A passage 17 is formed. The intake channel 17 has an opening width of, for example, about 160 m and communicates with an intake channel opening 19 via a curtain wall 18. The intake channel opening 19 is defined by a wave breakwater 20 connecting the base side of the dike 16 to the revetment 11 and a base 13 a of the sub breakwater 13. 1 shows an example in which the intake channel opening 18 shown in FIG. 1 is installed via an intake pump 21 to cool cooling equipment of two power plants, for example, condensers.

On the other hand, a submerged bank 23 is provided on the inlet side of the intake channel 17. The submerged bank 23 is provided to separate large-grained sand and small-grained silt from the sediment flowing into the harbor 14. For example, 75
It is divided into silt of fine particles of μ or less and sand of particles of 75 μ or more.

The submerge 23 extends over the entire width of the opening so as to cross the entrance of the intake channel 17, protrudes from the seabed toward the sea surface, and has a required height that does not guide sand components to the intake channel 17. The height is set to, for example, about several tens cm to 2 m. When the depth of the submerged embankment at the location where the sand pocket type harbor facility 10 is to be installed is about 4 m to 7 m, for example, 5.5 m, the wave direction is as shown in FIG. It is set to 5 m.

The longitudinal direction of the submerge 23 is configured to substantially coincide with a straight line A connecting both ends of the main breakwater 12 and the sub-breakwater 13. Then, a sheet flow state described later in which the sand moves in a layered state is generated, and a flush flow for transporting the sand into the sand pocket area is generated. By forming the submerged bank 24, the accumulation of sand on the front side of the submerged bank 23 is prevented.
The submerged levee 23 separates the sediment flowing into the harbor 14 into a sand component having a large particle size and a silt component being a fine particle having a small particle size. Among them, the sand component is due to the flash effect using the wave force of the waves,
It is carried to the inner part of the port via the flush flow area 24 shown in FIG. 2 and is deposited there. The inner part of the port forms a sand pocket area 25.

On the other hand, on the surface (sea surface) side of the port 14, FIG.
As shown in (2), a curved channel 26 is formed as a conduit from the port 15 to the intake channel 17, and is guided to the intake channel 17. The curved flow passage 26 and the intake passage 17 as a whole
It is formed in a channel shape of a letter shape (or inverted S shape). At this time, a submerged bank 23 is provided at the inlet of the intake channel 17 so that sand components are not mixed in the intake flow guided to the intake channel 17. The silt component of the fine particles out of the earth and sand flowing into the port 14 gets over the submerged levee 23, is mixed into the intake flow, and is guided to the intake passage 17. In order to prevent the silt mixed into the intake flow from settling or accumulating in the middle of the intake passage 17, the intake flow is provided with a flow speed of a predetermined value or more, for example, a flow speed of 20 cm / sec or more as described later.

In FIG. 2, the black arrow B represents the direction of movement of the sand deposited in the port by the flash effect, and the white arrow C represents the direction of movement of the silt due to the intake flow.

At a recent nuclear power plant, a large plant exceeding 1,000,000 kW is connected in series. When this large-sized power plant is installed, the flow rate of water intake is at least about 80 m ³ / sec or more per unit. Required.

When two power plants are installed based on the intake flow rate, the opening width of the intake passage 17 is set to, for example, 16 to secure a flow rate of, for example, 184 m ³ / sec.
In order to set a flow rate of 20 cm / sec or more to the intake flow in order to set the silt in the water channel 17 as little as possible, the water depth of the water intake channel 17 is, for example, about 4 m, and the top water depth of the submerged levee 23 is set to 0 m. About 3.5 m is required.

Further, a silt component is mixed in the intake stream flowing through the intake passage 17, and the silt component is guided to the intake pump 21 and the plant cooling equipment of the power generation plant together with the intake stream as cooling water. Since it is a fine particle, it is also suspended in ordinary seawater, and is less likely to damage or damage the water intake pump 21 and the plant cooling equipment, and does not cause any trouble in the operation of the power plant. The cooling water that has cooled the plant cooling system passes through the discharge pipe 27,
The water is discharged to the sea outside the port by the water discharge port 28.

Incidentally, the sand pocket type harbor facility 10 is designed such that the extension line A connecting the front ends of the breakwaters 12 and 13 substantially coincides with the direction (main wave direction) D of the specific wave having a high frequency of wave height appearance. Be composed. The direction D of the wave with a high frequency of wave heights is not actually specified in one direction as shown in FIG. 3, but changes in a certain angle range depending on geographical conditions such as terrain and weather conditions such as wind direction.

FIG. 3 shows this sand pocket type port facility 1
The planned installation location of 0 (the Pacific coast opened to the east) is 10
It shows the results of a survey over the years. From FIG. 3, it was found that the relationship between the wave height appearance frequency and the wave direction D is that the wave appearance frequency from the east (E) or east-southeast (ESE) direction occupies the main stream on an annualized basis. In this sand pocket type harbor facility 10, among the waves where the frequency of appearance of waves at the installation site is high, breakwaters 12, 13
In relation to the harbor 15 formed therebetween, a severe wave direction D, in this case, a wave from the east-southeast (ESE) is set as the main wave direction of the specific wave, and this main wave direction D The main breakwater 12 is configured to substantially coincide with the direction of the extension line A passing through the tip of the breakwater 12.

The sand pocket type harbor equipment 10 aims to increase the efficiency of maintenance dredging, and controls the fluctuation of the water surface and the flow rate of water intake in the harbor 14 according to the shape of the harbor, so that the sediment flowing into the harbor 14 is converted into sand and silt. This is a type in which the sand is positively separated and only the sand component is mainly deposited in the harbor 14.

In the sand pocket type port facility 10, the silt component of the earth and sand flowing into the port 14 is provided with a curved flow path 26 leading from the port 15 to the intake channel, so that the intake flow rate is equal to or less than the flow rate at which the silt is settled and deposited. In the harbor 14, the water is flowed in the intake channel 17 while always kept in a floating state without dropping, and the silt is sucked together with the cooling water into the intake pump 21 and discharged from the outlet 16 through the outlet 28. This drastically reduced the amount of silt deposited and reduced the amount of silt dredging.

As a method of controlling the sediment flowing into another port, there is a method of installing an offshore breakwater for controlling the sediment flowing offshore to reduce the amount of sediment. However, this method can make the offshore breakwater unnecessary. Therefore, construction costs can be reduced.

Although the sand flowing into the port 14 generally tends to be deposited near the port entrance, a flash flow is generated on the front of the submerged levee 23 by controlling and utilizing the flash effect of incident waves (waves). Then, it is flushed and deposited in a sheet flow state in the sand pocket area 25 at the back of the port. This is a harbor type in which dredging of reusable sand can be performed in a calm water area (sand pocket area 25) at the back of the harbor from the harbor 15.

The separation of the sand component and the silt component of the earth and sand flowing into the port 14 is performed by the submergence 23 installed at the entrance of the intake channel 17.
The evaluation based on the installation of the submerged bank 23 is performed as follows.

(Movement Mechanism of Sand) First, the movement mechanism of sand was measured by measuring the wave height or bottom flow velocity by a moving bed experiment using a wave water tank or a vibrating flowing water tank (Coastal Environment Engineering, supervised by Hitoshi Honma, University of Tokyo Press). When the bottom friction is increased, the bed flow (sand) moves in a sweeping state, the floating movement moves in a floating state, and the sheet flow moves in a layered state. It is known that the phenomena that occur are observed sequentially. It is known that in a sheet flow state, sand moves downstream in several layers in a layered state with a large bottom surface frictional stress.

Since sand has a larger particle size than silt, the amount of floating sand in a calm sea area decreases. In general, in a port facility, since the wave height (waves) is attenuated by the breakwater, sand is less likely to be transported to the port interior, and the sand is intensively deposited in the vicinity of the port entrance where the wave height is attenuated.

However, since the sand pocket type harbor facility 10 has the harbor layout structure shown in FIGS. 1 and 2, it receives waves from the east-southeast (ESE), which is one of the strictest wave direction conditions at the installation site. The vertical concentration distribution of sand in water is evaluated on the assumption that the wave height (incident wave height H) at the port entrance 15 due to the waves is 5.5 m and the wave period (T) is 11.75 seconds.

In the evaluation of the vertical concentration distribution of sand, a suspended sand concentration distribution calculation formula expressed by the following diffusion equation was used. The used coefficients were set by conducting field surveys.

[0051]

(Equation 1)

(Equation 2)

(Equation 3)

From the above formula for calculating the distribution of suspended sand concentration, the vertical concentration distribution of sand at the port 15 of the sand pocket type port facility 10 is shown in FIG.

The vertical concentration distribution of sand at the front of the submerged bank 23 is shown in FIG. However, the wave height (H) at the port entrance 15 due to the wave of the wave direction ESE is 5.5.
At this time, even at m, the front surface of the submerged embankment 23 is attenuated compared to the wave height at the port entrance, and becomes approximately 0.21 times, so that the wave height is found to be approximately 1.2 m.

On the other hand, the movement of the sand is caused by the maximum bottom shear force τ _m
Is known to exceed the critical bottom shear force τ _c , and with reference to FIG. 5, in the sand pocket type harbor facility 10, in front of the submerged ridge 23, the wave direction is severe, and It can be seen that it floats up to a height of about 10 cm from the surface and does not float any more.

As a result, even when the water depth at the inlet of the intake channel 17 is, for example, 4 m (or 5.5 m), the sand is distributed in a low layer at a dense vertical concentration distribution. For this reason, in the sand pocket type port facility 10, the submerged
Is installed to suppress the inflow of sand into the intake channel 17.
Even if the wave direction is different, the same calculation of the suspended sand vertical concentration distribution is calculated for each wave direction, and the submerged levee is used so that the vertical concentration distribution of dense sand is always obtained below the height of the submerged ridge 23. 23 are set.

The sand that has flowed into the port 14 is
When it accumulates in front of the submerged levee, the water depth in front of the submerged levee gradually becomes shallower, so that sand may get over the submerged levee 23 and flow into the intake channel 17, and it is necessary to prevent this flow. In order to move the sand from the front of the submerged bank 23 to the back side of the harbor, it is effective to generate a sheet flow state on the front of the submerged bank 23 by a flash effect due to waves.

The length of the main breakwater portion 12b of the main breakwater 12 is determined in order to cause a sheet flow state of sand in front of the submerged breakwater 23. At this port, the east (E)
Since the frequency of appearance of waves from the direction of the southeast (SE) direction is high, the length of the main breakwater 12 is selected in consideration of the frequency of appearance. By generating a sheet flow state on the front surface of the submerged levee 23 by the wave flush effect, sand on the front side of the submerged levee can be moved in a layered state to the back side of the harbor. Sand carried into the port is a sand pocket area 25 which is a calm area.
Intensively and effectively.

Next, conditions for generating a sheet flow state on the front side of the submerged bank 23 will be described with reference to FIG.

In the sand pocket type port facility 10, when the length of the main breakwater 12 is increased, the construction cost is increased.
The calmness in the harbor 14 increases due to the wave shielding effect of the main breakwater 12, and the shields number (dimensionless bottom surface friction stress) decreases. Therefore, the sheet flow state hardly occurs on the front side of the submerged bank 23. Conversely, if the length of the main breakwater 12 is reduced, the construction cost is reduced, but the calmness in the harbor 14 is deteriorated and the number of shields is increased, so that a sheet flow state is likely to occur. However, in this case, port 1
Due to the deterioration of the calmness of No. 4, the sand soars to a layer higher than the sea floor, so that it is necessary to increase the height of the submerge 23. Further, if the submerged levee 23 is made higher, the water level fluctuation in the water intake equipment (the screen and the water intake pump 21) of the power generation plant becomes large. Therefore, the design of the water intake equipment corresponding to the water level fluctuation is required, and this is accompanied by difficulty.

On the other hand, the sand pocket type harbor equipment 10
Then, in order to secure the calmness in the harbor 14, waves (waves)
The submergence 23 and the main breakwater 12 are designed to have a certain degree of shielding effect, and to effectively generate the sheet flow state by the wave flash effect when the wave height of the port 15 is, for example, 4 m or more in the front area of the submergence 23. Are set so that the direction A connecting the tips of the two may match the direction D of the main wave direction. The layout of the breakwaters 12 and 13 is set based on the harbor layout structure. In this case, the waterfall 15 is open in a direction crossing the main wave direction D.

As a method for accurately confirming that a sheet flow state has occurred in front of the submerged levee 23, there is a method based on a three-dimensional beach deformation simulation using a computer. There is also a method of setting the value of the limit shields number (0.5) to be a state as a guide and setting the value to a value equal to or more than the limit shields number (0.5).

Since the sheet flow state of sand generally occurs when the number of shields exceeds about 0.5, when the number of shields is high (for example, at a wave height of 4 m or more), 0.5 is set on the front side of the submerged bank 23. The length of the main breakwater 12 is determined so as to exceed it.

The relationship between the length (cover length) of the main breakwater 12 and the number of shields is represented as shown in FIGS. As shown in FIG. 7, when the cover length of the main breakwater 12 is variously changed with reference to the case where the tip of the main breakwater 12 is located on the extension line A in the direction of the submerge 23 (cover length 0). When the number of shields on the front side of the submerged bank 23 is obtained assuming a case where the water depth is 5 m and a case where the water depth is 7 m, it is expressed as shown in FIG. From FIG. 8, it can be seen from FIG. 8 that when the fogging length is negative, the shields number is 0.1 even when the wave height is about 2.5 m.
5 or more, and it is expected that a sheet flow state will occur on the front of the submerged bank 23.

The main breakwater 12 shown in FIGS.
FIG. 9 shows a simulation result obtained by performing a three-dimensional beach deformation simulation based on the relationship between the cover length and the number of shields. From FIG. 9, the sand pocket type harbor equipment 10
When the harbor layout structure is adopted, the sand passes through the front of the submerged levee 23 and is carried to the sand pocket area 25 at the back of the harbor.
It was confirmed that they were deposited.

(Movement Mechanism of Silt) Since silt is fine particles smaller than the particle size of sand, in a power plant intake port facility, it flows into the port 14 mainly by an intake flow.

In the sand pocket type port facility 10, in order to prevent the silt flowing in by the intake flow from settling,
It is necessary to conduct a sediment survey in the sea area around the planned site in advance, and if the intake flow velocity is set to be higher than the required speed, for example, 20 cm / sec or more based on the results of the sediment investigation, the intake flow will reach the critical bottom for the silt. It was confirmed that a force higher than the shearing force could be applied and the device could be moved in a floating state.

From the results of this confirmation, it can be seen that in one example of the sand pocket type port facility 10, when the intake flow rate flowing through the intake channel 17 is set to, for example, 20 cm / sec, the accumulation of silt in the intake channel 17 can be eliminated. . At this time, the water depth of the intake channel 17 is 5.5 m, and the intake flow rate is, for example, about 184.
m ³ / sec, the width of the intake channel 17 was set to 160 m. Under this harbor layout condition, no silt was deposited in the intake channel 17, and it was confirmed that the silt flowed out of the port from the outlet while flowing into the intake flow, which is cooling water.

(Confirmation of Influent Sand Reduction Effect by Submerged Breakwater) The moving mechanism of sand and silt and the function of separating sand and silt by submerged bank 23 have been described. FIG. 10 shows an example in which the amount of sand flowing into the inside is compared. In comparing the sand inflow with and without the submerged levee 23, the sand concentration distribution calculated by the procedure shown in FIG. 10 by solving the suspended sand concentration distribution calculation formula, which is a diffusion equation, based on the wave height appearance frequency shown in FIG. It was evaluated by the integral value.

From this evaluation result, the amount of sand flowing into the intake channel 17 (the amount of passage) when there is no submerged bank 23 is 13,840 m ^3.
In contrast, when the submerged embankment 23 was installed at the entrance of the waterway 17, it was confirmed that the depth was significantly less than 100 m ³ / year and 1 m ³ / year or less in any wave direction. It has been found that the sand pocket type port facility 10 has a large effect of preventing sand from flowing into the intake channel 17 by installing the submerged levee 23.

In the example of the sand pocket type harbor facility 10, the case where the installation site is the coast opened to the east side and the waves have many wave directions from the east (E) or the east-southeast (ESE) has been described. In areas where high wave directions change, there may be various variations in the harbor layout structure with respect to the wave incident direction. For example, in the case where the wave direction E of a wave having a high wave height appears frequently from the left side of the shore, the harbor layout structure shown in FIG. 11 is conceivable. In this sand pocket type port facility 10A, the arrangement structure of the portion F surrounded by the chain line becomes important.

Further, in the example of the sand pocket type harbor facility 10, an example is shown in which water is taken from the water intake channel 17 to the water intake facilities of two power plants. However, four additional power plants are provided in FIG. In the case where the power generation plants are arranged side by side, it is possible to cope with this by extending the wave breakwater 20 on the base 12a side of the main breakwater 12 and increasing the area of the intake channel opening 19. In this case, a sand pocket type port facility 10B capable of cooling four power plants is provided.

Further, when the sediment is mainly sand and has a small amount of silt as a result of the survey of the seabed sediment, as shown in FIG. A sand pocket type harbor facility 10 suitable for berthing can be used in a fishing port or the like. In the sand pocket type harbor facility 10C, an inner breakwater or a wave-removing submerged pier 30 instead of the dike is provided in the harbor 14 so as to face the sub-breakwater 13, and a portion surrounded by the sub-breakwater 13 and the wave-submerged levee 30 is provided. A boat having a shallow draft such as a fishing boat is anchored in the night area 31. The night area 31 corresponds to the intake channel 17 of the sand pocket type port facility 10 shown in FIG.

Also in the sand pocket type port facility 10 C shown in FIG. 13, the flash effect is generated by the waves from the port 15 on the front side of the submerged bank 23, so that the sand which tends to accumulate in the vicinity of the port 15 will The front surface is moved to the back side of the port in a sheet flow state, and the sand pocket area 25 at the back side of the port is moved.
To be deposited. By regularly dredging the sand pocket area 25, which is a quiet area, reusable sand can be dredged intensively and effectively. In this case, the route from the port entrance 15 to the night area 31 of the ship is
The non-deposited area of sand can be obtained by utilizing the flash effect of waves.

Further, the sand pocket type port facility 10 according to the present invention can be installed in parallel with existing port facilities. For example, a sand pocket type port facility 10 can be arranged in parallel with the existing port facility 1 shown in FIGS. 15 and 16.

When the existing port facilities 1 are installed side by side, there is no need to install a landing site in the newly added sand pocket type port facilities 10, and the landing site 32 of the existing port facilities 1 is not required.
The construction cost of the main breakwater 12 and the sub-breakwater 13 can be reduced.

[0076]

As described above, the sand pocket type port facility according to the present invention is constructed as described in claim 1 and forms an intake channel in a port partitioned by the main breakwater and the sub-breakwater. Then, by installing a submerged dike at the entrance of this intake channel, large submerged sand and small particle size silt are separated at the submerged dike, and the silt component is guided to the intake channel,
Since silt is prevented from accumulating in the port, the amount of dredging can be reduced, and the operating cost can be reduced.

Further, since the sand component flowing into the harbor can be separated from the silt component by the submerged levee and deposited in the sand pocket area, a dredging plan for the reusable sand component can be efficiently planned. On the other hand, sand-pocket type port facilities do not require the construction of breakwaters offshore, lowering construction costs and improving economic efficiency.

In the sand pocket type harbor facility according to the second aspect, since the direction connecting the submerged levee and the tip of the main breakwater almost coincides with the main wave direction in which the wave height appears frequently, there is a wave from the vicinity of the main wave direction. When the wave height was more than a certain level, a flush flow area was formed from the port entrance to the port depth on the front side of the submerged levee, causing a flush flow that caused a sheet flow condition. The sand on the front of the submerged levee does not accumulate and is transported to the sand pocket area at the back of the harbor by the flash current caused by the waves to be accumulated. Therefore, the dredging of sand can be efficiently performed in the calm area at the back of the port, and the dredging operation can be efficiently and efficiently performed. Since the proportion of the silt component contained in the sand component deposited in the sand pocket region is small, the sand component obtained by dredging can be effectively reused.

In the sand pocket type port facility according to the third aspect, the port formed between the leading end of the main breakwater and the sub-breakwater is directed in a direction intersecting with the main wave direction, so that the front side of the submerged breakwater is provided. The effect of waves can be used to create a flash effect, and sand accumulates on the front side of the submerged levee,
Sand can be prevented from flowing into the intake channel.

In the sand pocket type port facility according to the fourth aspect, the length of the main breakwater is set so that the number of shields on the front side of the submerged bank is equal to or larger than the limit shields number (0.5) in high waves. Therefore, it is possible to effectively prevent sand from accumulating on the front of the submerged levee due to the wave force caused by the waves, and to move the accumulated sand toward the back of the port.

In the sand pocket type port facility according to the fifth aspect, since a flow rate higher than the critical bottom shear force is applied to the intake flow guided through the intake channel, the silt component flowing over the submerged dike and flowing into the intake channel. Can be effectively prevented from settling and accumulating in the intake channel, and the accumulation of silt components in the harbor can be efficiently reduced.

In the sand pocket type port facility according to the sixth aspect, the height of the submerged levee is set so as to obtain a concentration distribution of dense sand below the height of the submerged levee, so that the sand components It is possible to effectively and reliably prevent the water from getting over and flowing into the intake channel.

In the sand pocket type port facility according to claim 7, a night area for anchoring in the port can be formed and used for a fishing port or the like. A sand pocket area for depositing a sand component can be formed in the portion, and effective reuse can be achieved by dredging the sand deposited in the sand pocket area.

According to the sand pocket type port facility of the eighth aspect, even if a night area is formed in the port, it is possible to efficiently eliminate the accumulation of sand on the channel from the port entrance to the night area.

[Brief description of the drawings]

FIG. 1 is a harbor layout diagram showing one embodiment of a sand pocket type harbor facility according to the present invention.

FIG. 2 is a diagram illustrating the movement relationship between sand and silt in a port of the sand pocket type port facility according to the present invention.

FIG. 3 is a diagram showing a relationship between a wave height appearance frequency and a wave direction (main wave direction) at an installation site of a sand pocket type port facility.

FIG. 4 is a view showing a concentration distribution of sand at a port entrance of a sand pocket type port facility.

FIG. 5 is a diagram showing a concentration distribution of sand in front of a submerged embankment of a sand pocket type port facility.

6A is a diagram for evaluating the relationship between the length of the main breakwater and the number of shields at the front of the submerged levee, and FIG. 6B is a diagram illustrating the construction cost, dredging cost, calmness within the port, and the number of shields at the front of the submerged levee. To find the optimal main breakwater length.

FIG. 7 is a harbor layout diagram showing the cover length of the main breakwater.

FIG. 8 is a diagram showing the relationship between the cover length of the main breakwater and the number of shields in front of the submerged levee.

FIG. 9 is a view showing a result of evaluating and analyzing the sand pocket type harbor facilities using a three-dimensional beach deformation simulation.

FIG. 10 is a diagram showing a procedure for confirming the sand inflow effect by a submerged levee installed in a harbor of a sand pocket type harbor facility, and a result of the confirmation.

FIG. 11 is a simplified port layout diagram showing another embodiment of the sand pocket type port facility according to the present invention.

FIG. 12 is a simplified port layout diagram showing a third embodiment of a sand pocket type port facility according to the present invention.

FIG. 13 is a simplified port layout diagram showing a fourth embodiment of the sand pocket type port facility according to the present invention.

FIG. 14 is a diagram showing a comparison between a typical port water intake system and a tunnel water intake system as power plant water intake facilities.

FIG. 15 is a layout diagram of an existing port facility.

FIG. 16 is a layout diagram of another existing port facility.

[Explanation of symbols]

10, 10A, 10B, 10C Sand pocket type harbor equipment 11 Seawall 12 Main breakwater 12a Base 12b Main breakwater 13 Sub breakwater 13a Base 13b Subbreakwater 14 Port 15 Port entrance 16 Drainage 17 Intake channel 19 Intake channel open channel Reference Signs List 20 Wave breakwater 21 Intake pump 23 Submerge 24 Flash flow area 25 Sand pocket area 26 Curved flow path (conducting flow path) 30 Inner breakwater (wave-removal dike) 31 Night area

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) E02B 3/00 E02B 3/04

Claims (8)

(57) [Claims] 1. A main breakwater protruding from the seawall to the sea side,
A sub-brake which is opposite to the main breakwater at intervals along the seawall, a port which is divided by both breakwaters, and which is connected to the outside of the port via the port entrance, and which is installed inside this port so as to face the sub-breakwater A dike that defines the intake channel, and a submerged dike installed at the entrance of the intake channel, which can separate the silt component from the sand component and can guide the silt component to the intake channel. A sand pocket type harbor facility characterized by forming a sand pocket area to be deposited separately from silt components. 2. A submerged levee is provided across the entrance of the intake channel, and a direction connecting the submerged levee and the tip of the main breakwater is substantially coincident with a main wave direction. 2. A sand pocket type port facility according to claim 1, wherein the sand flowing from the port entrance from the port entrance to the port interior forms a flush flow region in which a sheet flow state is generated by the force of the wave to generate a flush flow carrying the sand to the sand pocket region. . 3. The main breakwater has a base extending from the revetment to the sea side and a wavebreak part on the tip side mainly receiving waves is formed in a substantially U-shape or inverted shape, and the sub-breakwater has a base and a tip. 2. The wave-breaking part on the side is formed in an inverted shape or in a shape of a square, and the port formed between the tip portions of both breakwaters is opened so as to face a direction crossing the main wave direction. The described sand pocket type harbor equipment. 4. The main breakwater is set to have such a length that a sheet flow state occurs when the number of shields on the front side of the submerged bank is equal to or more than the limit shields number (0.5) during high surf.
Sand pocket type harbor facilities described in. 5. An S-shaped or inverted S-shaped channel is formed in a harbor formed by a main breakwater and a sub-breakwater from a port entrance to an intake channel, and an intake flow guided through the intake channel has a critical bottom shear force or more. The sand pocket type port facility according to any one of claims 1 to 4, wherein a water intake flow rate is provided. 6. The submerged levee is the length and direction of the main breakwater,
The sand pocket type port facility according to any one of claims 1 to 5, wherein the height is set from the concentration distribution of sand on the front side of the submerged bank, and a concentration distribution of dense sand is obtained below the height of the submerged bank. . 7. A main breakwater protruding from the seawall to the sea side,
A main breakwater and a sub-breakwater, which are oppositely provided along the seawall, and a port which is divided by both breakwaters and is connected to the open sea through a port entrance, and is installed in the harbor facing the sub-breakwater, A sand-pocket type harbor having an inner breakwater that partitions a night area of a ship and a submerged dike installed at an entrance of the night area of the ship, wherein a sand pocket area is formed on a deep side of the port. Facility. 8. A method according to claim 8, wherein at least one of the sub breakwater, the inner breakwater, and the seawall is configured as a loading dock, while the direction connecting the tip of the submarine breakwater and the tip of the main breakwater substantially coincides with the main wave direction. The sand pocket type harbor facility according to claim 7, wherein the sea route leading to is constructed in a non-deposited structure of sand.