• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to a method for transporting sediment, in particular sand along a bottom of a water mass, comprising the steps of: placing at least a flow in the water mass at a starting position on the bottom an obstacle, such that the flow sets a part of the soil around the at least one obstacle in motion and forces it in a desired direction of transport; and - moving the at least one obstacle to a next position in the direction of transport after a period of time. The invention further relates to a device for performing the method, comprising at least one obstacle that can be placed on the ground and means for displacing the at least one obstacle in a desired direction of transport.
    公开号:NL2025787A
    申请号:NL2025787
    申请日:2020-06-08
    公开日:2020-12-11
    发明作者:Cornelis Groenendijk Floor
    申请人:Arcadis Nederland B V；
    IPC主号:
    专利说明:

    METHOD AND DEVICE FOR TRANSPORTING THE SEDIMENT ALONG
    The invention relates to a method and device for transporting sediment, in particular sand, along a bottom of a water mass. More specifically, the invention relates to a method and apparatus for transporting sand from a deeper part of a seabed to a coast to form a natural seawall.
    Dunes form a natural seawall and protect coastal areas beyond. Dunes were created in the past because waves transported sand to the coast. The usually onshore wind pushed the sand inland where it was captured by vegetation. This is how the dunes were formed and fed for centuries.
    This process has gradually come to a standstill as the bottom deepened as a result of the sand being transported to the coast, while at the same time the sea level was rising. As a result, the waves could no longer mobilize the sediment on the bottom. As a result, no more sand i5 was supplied from the deeper parts of the coastal foundation - the part of the coastal profile between 20 m and the 12 m depth line - to the 'near shore' coastal zone - the part of the coastal profile from the 8 m depth line to the beach.
    However, the sea level rose further, as a result of which the waves at the deeper part could no longer move the bottom and could no longer generate coastal transport.
    As a result, the supply of sand came to a standstill and the waves started to attack the coast, instead of building it up. Sand was knocked off with every storm, referred to as coastal erosion, but in quiet periods that sand was no longer supplied. This is how coastal erosion developed over the years; the phenomenon that on average more sand disappeared from a coastal section than was deposited on it.
    In view of the importance of dunes for coastal protection, the Dutch government decided in 1990 that the coast as it was then would be maintained by means of sand replenishment. This artificially restores the lost supply of sand on a geological time scale. Since the 1990s, an average of 7 million m3 of sand has been replenished every year in coastal sections along the Dutch coast. The sand is extracted in the deeper parts (deeper than -20 m) and brought to the coast.
    The technique of sand replenishment (extraction, transport, replenishment) is an artificial alternative to the disappearance of a natural constant supply of sand from the shallow marginal sea to the coast. During beach replenishment, the sand is pumped to the beach by a trailing suction hopper dredger via a pipeline. Bulldozers distribute the sand further on the beach.
    In the previous periods, several studies have already been carried out into how sand behaves in the dynamic coastal zone. For example, the European project NOURTEC (NOURishment TEChnology), part of the European research program MAST (Marine Science and
    Technology), has shown that underwater shore nourishment is very effective: hips / cordiaewopaewprolectrcn / S62Wfactcheet / en. Sand deposited on the shallow foreshore (around a depth of 6 m) is within reach of the waves. The wave forces transport the sand towards the coast. Active beach replenishment by means of pumping sucked-up sand via a pipeline is then not necessary.
    Climate change is now starting to persist. There is a great need to reduce CO 2 emissions. Conventional replenishment of the Dutch coast is accompanied by high CO emissions. The extraction and transport of the sand with dredgers requires a lot of energy, which is supplied to dredgers by combustion engines running on fuel oil.
    The object of the invention is to provide a method and device with which sand can be supplied with a lower CO 2 emission than is feasible with the conventional replenishment techniques. According to the invention this is achieved in a method as described in the preamble by the steps of : - placing at least one obstacle at a starting position on the bottom at a flow in the water mass, such that the flow sets a part of the bottom around the at least one obstacle in motion and forces it in a desired transport direction; and - moving the at least one obstacle to a next position in the direction of transport after a period of time.
    Thus, without making use of pistons and pipelines, a sand transport can be initiated in a specific direction simply by suitable placement of the at least one obstacle.
    In an application of the method, the body of water can be a sea, the current can be a tidal current, and the sand can be transported from a deeper part of the seabed towards the coast. For example, the obstacle placed on the bottom ensures that sand is transported from the deeper parts of the coastal profile in the direction of the coast and thus comes within the reach of wave forces that can bring the sand further up the coast. The invention can thus make use of the natural forces that are present in the North Sea every day, namely tide and waves. The invention is based on the phenomenon of "scouring"; when an obstacle is placed in the coastal zone, an excavation pit is created. The tidal current accelerates around the obstacle and carries sediment with it. An excavation pit is created at the base of the obstacle until a certain equilibrium is reached. This principle therefore forms the basis of the operation of the invention; placing an object in a coastal zone induces a temporary sand transport.
    In order to accelerate the sand transport in the direction of the coast, the step of moving the at least one obstacle in the transport direction can be repeated several times.
    In an embodiment of the method the at least one obstacle is profiled and the profile of the at least one obstacle determines the direction of transport. The shape of the obstacle influences the size of that sand transport; a shape that produces a large acceleration will result in a larger excavation pit, and thus cause a larger sand transport.
    The ground in the vicinity of the at least one obstacle can be monitored and, on the basis of the monitoring, it can be determined when the at least one obstacle will be moved to a next position. In this way, the sand transport to the coast can be controlled.
    To increase the yield and to ensure an even replenishment of sand, several obstacles can be placed on the bottom in a pattern and moved synchronously or not.
    The invention also relates to a device for transporting sediment, in particular sand along a bottom of a body of water, with which the method described above can be carried out. According to the invention, such a device is provided with at least one obstacle that can be placed on the ground and means for moving the at least one obstacle in a desired direction of transport. The displacement means can be electrically, hydraulically or pneumatically driven. The displacement means can for instance comprise driven wheels or crawlers, with which the obstacle can be moved over the ground. It is also conceivable that the displacing means comprise displaceable suction anchors with electric pumps, tie rods and a control, whereby it is possible, as it were, to have the obstacle "walk" over the ground.
    As discussed above, the at least one obstacle can be profiled to determine the direction of transport. In particular, the at least one obstacle can have a projecting part pointing in the direction of transport.
    In order for the obstacle to be effective in two substantially opposite directions of flow of the water, for example in tidal flow, the obstacle may be symmetrical with respect to a line running transversely to the directions of flow. For example, the shape of the obstacle may be substantially triangular, with a base substantially parallel to the coastline and two oblique sides directed from the base to the coastline that converge at a vertex - or three-dimensionally, an edge, The triangle is a form that causes a great acceleration, and thus causes a great sand transport.
    The at least one obstacle can have hollow parts on both sides of the protruding part. The slightly concave profile of the sloping sides ensures an even conduction of the flow from the base towards the tip.
    In order to ensure that the obstacle (s) is / are only moved at a desired moment and in a desired direction, the device can further be provided with means for anchoring the at least one obstacle at least temporarily on the ground. These anchoring means, whether temporary or not, may comprise one or more suction anchors.
    The device according to the invention may be provided with means for monitoring the ground in the vicinity of the at least one obstacle. Such monitoring means can comprise sensors which detect the condition of the ground and, on the basis thereof, issue a signal which is a measure of the operation of the obstacle. The sensors can form part of a so-called “multibeam soil scanner”.
    In one embodiment, the device described above is further provided with means connected to the monitoring means for determining when the at least one obstacle must be moved to a next position. These determining means may comprise a processor which receives and processes signals from the sensors and on the basis thereof determines that an equilibrium situation has been reached. This happens when the obstacle has stood in a certain place for some time, and results in the sand transport coming to a standstill. At that moment the determining means indicate that the obstacle must be moved.
    As stated above, an even sand transport can be achieved when the device is further provided with a plurality of obstacles that can be placed in a pattern on the bottom and that may or may not be displaced synchronously.
    The invention is now elucidated on the basis of an example, reference being made to the accompanying drawings, in which: fig. 1 shows a cross-section of a coastal profile with a wave-dominated zone and a portion where the invention has effect; FIG. 2 is a perspective view of a coast with an embodiment of the device according to the invention with a single obstacle and the associated sedimentation and erosion patterns; FIG. 3 is a perspective view of the coast with another embodiment of the device according to the invention with a number of obstacles and the associated sedimentation and erosion patterns; FIG. 4 is a schematic representation of an obstacle on the bottom of a water mass and the deformation of the bottom under the influence of flow of the water mass; and FIG. 5 is a schematic representation of an embodiment of the method according to the invention.
    When an obstacle 1 is placed on a bottom 2 of a water mass 3 (Fig. 4), a flow F of the water mass is in principle disturbed by this. This disturbance of the water flow F leads to an accelerated flow along the obstacle and a turbulent wake Z downstream from the obstacle 1, whereby sediment, for example sand, is loosened from the bottom 2. This loosened sand is carried along by the flowing water mass, and eventually settles at some distance downstream of the obstacle 1 when the speed of the water flow becomes low. The loosened sand can thus be transported over a specific distance.
    In this way, a cavity or excavation pit 4 (shown in dotted lines) in the bottom 2 eventually arises around the obstacle 1, while further downstream of the obstacle 1 an accumulation 5 of sand (also shown in dotted lines) arises.
    The bottom shape around the obstacle is balanced and matches the flow profile.
    Where the water flows faster it is deeper and where there is lee it is shallower.
    This principle is the basis of the operation of the invention.
    Namely, by placing the obstacle 1 in a different position after some time (indicated by dotted lines in Fig. 4), such sand transport can also be caused there.
    Thus, by repeatedly moving the obstacle 1 in the direction of the flow, a considerable amount of sand can ultimately be transported in the direction of flow.
    However, when the flow direction changes, the transport direction of the loosened sand will also change.
    In the case of a tidal current, a complete reversal of the flow direction takes place.
    As a result, sand on the other side of the obstacle 1 would be loosened and transported in the opposite direction, so that the net sand transport over a complete cycle of ebb and flow would be nil.
    In order to ensure that both with outgoing tidal currents and emerging tidal currents {in Fig. 2 and FIG. 3, shown by double arrows Fr) to achieve the same direction of transport T of the loosened sand, the obstacle 1 can be of substantially symmetrical design with respect to a line of symmetry 6 which runs substantially transversely to the tidal flow Fr.
    In this case, the obstacle 1 can have a protruding part 7, which points in the direction of transport T.
    In the example shown, the obstacle is | substantially triangular in plan view, with a base 8 that is substantially parallel to the rising and falling tidal currents, and two sides 9 that converge in a top, which in the three-dimensional obstacle 1 is formed by an end edge 10. The basic shape of the obstacle 1 is therefore an isosceles triangle, albeit that the legs are not straight but have a concave profile.
    As a result, the flow hitting the upstream side 9 is evenly deflected in the direction of the end edge 10, i.e. towards the conveying direction T.
    The transport direction T is directed towards the coastline C, and is thus transverse to the tidal flow Fr, which runs substantially parallel to the coastline C.
    Due to the uniform deflection by means of the hollow profiled side 9, the flow is accelerated there and the sand washes away (erosion, schematically indicated by the sand clouds E), after which the sand precipitates again at some distance to the coast of the obstacle 1 (sedimentation, indicated through the sand clouds S). Due to the symmetrical shape of the obstacle 1, this phenomenon occurs both with the emerging tidal current and with the opposite downward tidal current.
    Thus, over a complete tidal cycle, a net transport of sand is created in the desired direction, in this case in the direction of the coastline C. In order to enhance this effect, the obstacle 1 can further be provided with flow guides, such as, for example, twisted current seams to keep flowing water in. to bring a whirl.
    As mentioned, over time around the obstacle | a balance. The bottom shape around the obstacle 1 then matches the flow profile, with deeper parts where the flow speed is higher and shallower parts in the lee of the obstacle 1. Then it is time to move the beacons and the obstacle 1 over a certain distance, at for example, to move a few meters in the direction of coastline C, such that the accumulated sand S2 is stirred up again by the tidal current and transported further to the coast.
    For moving the obstacle | displacing means (not shown here) can be provided, for instance in the form of large wheels with which the obstacle 1 can be moved over the ground 2. Instead of wheels, tracks are also conceivable. The wheels or tracks can be electrically, hydraulically or even pneumatically driven, although in practice an electric drive is preferred. It is also possible to have the obstacle 1 "walk" over the bottom 2 by means of movable suction anchors with electric pumps, pull rods and a control, which together can form the displacement means. The electrical energy required for the movement can be generated by solar panels or wind turbines and can be stored in batteries.
    When the obstacle | is placed in a certain position, it must remain there until a state of equilibrium is reached. To this end, the obstacle 1 in the example shown is of heavy design, for instance made of stainless steel or composite material weighted with concrete. When the weight of the obstacle 1 is insufficient to keep it in place, it can also be provided with anchoring means (not shown either), for instance in the form of one or more suction anchors. These suction anchors can simultaneously play a role in the displacement of the obstacle 1, as described above.
    An electronic control system can be used to determine when the obstacle 1 must be moved (not shown here). This control system can cooperate with sensors (not shown here either) that monitor the changes to the ground 2 and, on the basis of signals from those sensors, can determine when an equilibrium position of the ground is formed and how far the obstacle 1 must then be moved. As mentioned, for example, a multibeam bottom scanner can be used for this.
    With a view to safety, the establishment must have adequate signals for through shipping and for fishing. For this it is necessary that part of the obstacle 1 protrudes above water. This can be a slender part, for example masts or a frame, that has little resistance from the waves.
    To increase the transport capacity of the device, several obstacles | placed in close proximity to each other in a pattern (Fig. 3). These obstacles 1 can be moved either synchronously or in a certain order in the direction of the coast C, somewhat in the way a crab moves its legs. The facility is therefore referred to as "sand crab".
    Depending on the need for sand replenishment, such devices can be placed at several places in the coastal zone, so that a coastward transport of sand occurs at several places.
    The steps of the method according to the invention are summarized in FIG. 5. In the first IO instance, an obstacle | placed at a certain position on the bottom 2 of a body of water 3, for example the seabed near the coast (step 100). Subsequently, the obstacle 1 can be anchored at that position (step 101). As a result of the presence of the obstacle 1, the flow is influenced, whereby sand is loosened from the bottom 2 in the desired direction, for instance being transported to the coast. The condition of the floor 2 around the obstacle 1 is continuously monitored (step 102). On the basis of data from that monitoring, it is determined whether an equilibrium condition has been established (step 103). If it is not yet the case, the status is further monitored (step 102). When it is determined that equilibrium has been reached, the obstacle 1 is moved a certain distance (step 104). In the new position, the obstacle becomes | anchored again (step 101) and the transport of sand continues.
    The device according to the invention is thus not a static device; it is a device that moves slowly. The speed of movement is determined by the speed at which the equilibrium position of the bottom is reached. With turbulence caused by high waves and with spring tide, the equilibrium situation will be set earlier than with low waves and neap tide. The displacement of the obstacle must therefore be determined by a mechanism that measures the ground changes around the obstacle.
    As mentioned, this technique offers an integral transport of sand. Strictly speaking, all three phases of conventional sand replenishment by means of suction, pumping and distribution of sand are included; I. Win; if winning means mobilizing sand and preparing it for transport, then the mechanism of "scouring" is equivalent to winning.
    2. Transport; the asymmetrical shape of the obstacle creates a transport of sand towards the coast.
    3. Supplementation; "Scouring" is local and the sand will sediment by itself at some distance from the obstacle.
    The series of “win-transport-replenish” has thus become a continuum.
    The invention is applicable to any sandy coast where there is a tidal current. It is applicable to the portion 11 of the coastal profile (Fig. 1) where the waves usually do not generate a coastal sand transport because it is too deep there. The waves present will reinforce the principle. Depending on how robust the system is implemented and the scale size, the system can operate continuously; it 'stands' (actually creeps) in the coastal zone and the structure moves a volume of sand in the direction of the coastline C in the wave-dominated zone 12 of the coastal profile due to the two flow-guiding sides with each ebb and flood current. about.
    The invention could also work in a situation where water is constantly flowing in the same IO direction, for example in a river. The obstacle would then not have to have a flow-favoring profile shape on two sides, but only on one side.
    The environmental impact of the method and device according to the invention is minimal. The device according to the invention is a large and heavy installation that moves at a low speed, determined by an electronic system, electrically driven in the direction of the coast. The installation generates only minimal emissions. The only environmental burden is the construction, placement and relocation of the facility. After a cycle of a "coastward crawl", the facility must be moved seaward again.
    The method and device according to the invention are particularly cost-effective; the costs are mainly in the construction of the facility. Operational costs are limited; once placed in the sea, the device can work almost passively and therefore at minimal cost.
    The invention makes it possible to effect a coastal sand transport in a semi-passive manner. This sand transport is not large, but it is continuous with every ebb and flow current. The interior can easily be scaled up. The ideal scale size depends on the hydraulic regime and the sand characteristics. In any case, the invention can be scaled up per installation - for example a device with 8 obstacles or with 20 obstacles - but also in number, by placing more devices per coastal section. All this also depends on the mutual influence of the obstacles.
    The device according to the invention is reliable because it is a relatively simple installation with few movable parts.
    Robustness is a design requirement for the device. The facility must be seaworthy in the coastal zone seaward of the surf zone in extreme conditions. The device is fitted with suction anchors that are activated during extreme storms. The facility does not enter the surf zone, but rather ensures that the sand from deeper parts of the coast is transported in the direction of the surf zone. That's where the waves take over; the wave-driven sand transport that ensures the construction of a coast
    Although the invention has been described above with reference to a number of examples, it will be understood that it is not limited thereto and can be varied in many ways within the scope of the following claims.
    权利要求:
    Claims (16)
    [1]
    1. Method for transporting sediment, in particular sand along a bottom of a body of water, comprising the steps of: - placing at least one obstacle at a starting position on the bottom at the location of a flow in the water mass, such that the flow sets a part of the soil around the at least one obstacle in motion and forces it in a desired direction of transport; and - moving the at least one obstacle to a next position in the direction of transport after a period of time.
    [2]
    A method according to claim 1, wherein the step of moving the at least one obstacle in the direction of transport is repeated several times.
    [3]
    A method according to claim 1 or 2, wherein the at least one obstacle is profiled and the profile of the at least one obstacle determines the direction of transport.
    [4]
    A method according to any one of the preceding claims, wherein the ground in the vicinity of the at least one obstacle is monitored and it is determined on the basis of the monitoring when the at least one obstacle is to be moved to a next position.
    [5]
    A method according to any one of the preceding claims, wherein a plurality of obstacles are placed on the bottom in a pattern and are moved synchronously or not.
    [6]
    A method according to any one of the preceding claims, wherein the body of water is a sea, the current is a tidal current, and the sand is transported from a deeper part of the seabed in the direction of the coast.
    [7]
    7. A method according to claims 3 and 6, wherein the at least one obstacle is profiled in such a way that the direction of transport with an emerging tidal current is substantially the same as the direction of transport with a descending tidal current.
    [8]
    Device for transporting sediment, in particular sand, along a bottom of a body of water, comprising at least one obstacle that can be placed on the bottom and means for displacing the at least one obstacle in a desired transport direction.
    [9]
    Device according to claim 8, wherein the at least one obstacle is profiled to determine the direction of transport.
    [10]
    Device as claimed in claim 9, wherein the at least one obstacle has a protruding part pointing in the direction of transport. I.
    [11]
    Device as claimed in claim 9 or 10, wherein the obstacle is symmetrical with respect to a line running transversely to two substantially opposite directions of flow of the water mass.
    [12]
    Device as claimed in claims 10 and 11, wherein the at least one obstacle has hollow parts on either side of the protruding part.
    [13]
    13. Device as claimed in any of the claims 8-12, further provided with means for anchoring the at least one obstacle at least temporarily on the ground.
    [14]
    Device according to any one of claims 8-13, further provided with means for monitoring the bottom in the vicinity of the at least one obstacle.
    [15]
    Device as claimed in claim 14, further comprising means connected to the monitoring means for determining when the at least one obstacle is moved to a next position.
    [16]
    16. Device as claimed in any of the claims 8-15, further provided with a plurality of obstacles that can be placed in a pattern on the bottom and that may or may not be displaced synchronously.
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    同族专利:
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    引用文献:
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    US3892075A|1973-10-29|1975-07-01|Michael Edward Tibbett|Apparatus for vortex generation to precipitate suspended particles in fluid bodies|
    US7461998B1|2003-04-29|2008-12-09|Beach Restorations, Inc.|Coastal erosion mitigation solution |
    US20120315090A1|2011-06-10|2012-12-13|Farrell Jr Joseph Edward|Coastal recovery utilizing repositionable beach module|
    US9151008B1|2014-08-22|2015-10-06|Robin G Carstens|Wave break device|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    NL2023282|2019-06-08|
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