Abstract
A river training structure includes a longitudinal groyne placed in the river. The groyne extends in flow direction of the river with water of the river along both longitudinal sides of the groyne. The river training structure includes blocks, each block being constituted by a central part and four or more legs extending from the central part such that the central part and legs define a three-dimensional configuration allowing a multiple of said blocks to inter-engage with each other three-dimensionally when stacked onto each other. The groyne is constructed from a multiple said blocks irregularly stacked onto each other and engaging with each other to form a dam body of inter-engaging blocks, the dam body having a longitudinal slope at the navigation channel side of the dam body.
Claims
1.-22. (canceled)
23. A river training structure for a river, wherein the river has a flow direction, a bank, and a navigation channel with a bottom; wherein the river training structure comprises a groyne placed in the river; wherein the groyne is a longitudinal groyne extending in flow direction of the river with water of the river along both longitudinal sides of the longitudinal groyne; wherein the river training structure comprises concrete blocks, each block being constituted by a central part and four or more legs extending from the central part such that the central part and legs define a three-dimensional configuration allowing a multiple of said blocks to inter-engage with each other three-dimensionally when stacked onto each other; wherein the longitudinal groyne is constructed from a multiple of said blocks irregularly stacked onto each other and engaging with each other to form a dam body of inter-engaging blocks, the dam body having a longitudinal slope at the navigation channel side of the dam body.
24. The river training structure according to claim 23, wherein the longitudinal groyne is placed at a distance from the bank.
25. The river training structure according to claim 23, wherein the longitudinal groyne is placed on the edge of the navigation channel.
26. The river training structure according to claim 23, wherein the dam body of inter-engaging blocks rests directly on a sand or clay bottom of the river.
27. The river training structure according to claim 23, wherein the longitudinal groyne is a construction consisting of about only said blocks.
28. The river training structure according to claim 23, wherein the dam body of inter-engaging blocks has a further longitudinal slope at the bank side.
29. The river training structure according to claim 23, wherein the slope(/s) has(/have) a grade in the range of about 80% to about 120%.
30. The river training structure according to claim 23, wherein said three-dimensional configuration defines: a smallest bounding sphere with a radius in the range of about 15 to about 35 cm; and/or a smallest bounding cube with edges each having a length in the range of about 20 to about 50 cm.
31. The river training structure according to claim 23, wherein the blocks are configured with dimensions allowing it to be dumped by a stone dumping vessel having one or more of: a side dumper, a hopper barge, clamshell crane.
32. The river training structure according to claim 23, wherein the longitudinal groyne has an open structure allowing water to pass through the longitudinal groyne.
33. The river training structure according to claim 23, wherein the longitudinal groyne has a length of more than 500 meters.
34. The river training structure according to claim 23, comprising a series of two or more of said longitudinal groynes placed in line with each other over a total length of more than 500 meters and separated by water passages.
35. The river training structure according to claim 23, wherein the longitudinal groyne has a centre axis extending above and over end toe constructions of transverse groynes which: extend or, in case the transverse groynes have been removed, previously extended from the bank transverse into the river.
36. A system comprising: a river training structure according to claim 23, and a river having a flow direction, a bank, and a navigation channel with a bottom.
37. A method for training a river, wherein the method comprises the step of providing a longitudinal groyne in the river, which longitudinal groyne extends in flow direction of the river with water of the river along both longitudinal sides of the longitudinal groyne; wherein the longitudinal groyne provided comprises blocks, which are each constituted by a central part and four or more legs extending from the central part such that the central part and legs define a three-dimensional configuration allowing a multiple of said blocks to inter-engage with each other three-dimensionally when stacked onto each other; and wherein the longitudinal groyne is provided by dumping of a plurality of said blocks to form a dam body of said blocks irregularly stacked onto each other and inter-engaging with each other, the dam body having a longitudinal slope at the navigation channel side of the dam body.
38. The method according to claim 37, wherein the blocks are dumped on and along the edge of the navigation channel of the river to erect the longitudinal groyne on the edge of the navigation channel.
39. The method according to claim 37, wherein the river to be trained comprises a series of transverse groynes extending from a river bank transverse into the river, each transverse groyne having at its river end an end toe construction; wherein the blocks are dumped along an imaginary line such that the longitudinal groyne obtained has a center axis extending over the end toe constructions of the transverse groynes and connecting the ends of the transverse groynes; and wherein, after having provided the longitudinal groyne, the part of the transverse groynes projecting above the bottom of the river is at least partially removed.
40. The method according to claim 37, wherein the blocks are dumped by a stone dumping vessel sailing in the navigation channel of the river.
41. The method according to claim 37, wherein the blocks are dumped such that the dam body obtained has at the navigation channel side of the dam body a slope with a grade in the range of about 80% to about 120%.
42. The method according to claim 37, wherein said three-dimensional configuration defines a smallest bounding sphere with a radius in the range of about 15 to about 35 cm; and/or a smallest bounding cube with edges each having a length in the range of about 20 to about 50 cm.
Description
BRIEF DESCRIPTION OF THE DRAWING
[0051] The invention will be explained further with reference to the drawings. In these drawings:
[0052] FIG. 1A schematically shows, in cross-section, a left part of a river provided with a prior art transverse groyne.
[0053] FIG. 1B shows the same schematical view as FIG. 1A, in which a river training structure with a longitudinal groyne according to the invention has been provided, the prior art transverse groyne still being present.
[0054] FIG. 1C shows the same schematical view as FIG. 1B, in which a river training structure with a longitudinal groyne according to the invention has been provided, and in which the prior art transverse groyne has been removed.
[0055] FIG. 2 shows a similar schematical view as FIG. 1C, in which however a prior art longitudinal groyne has been provided, and in which the prior art transverse groyne has been removed.
[0056] FIG. 3 schematically shows in top view (FIG. 3A) and in cross-section (FIG. 3B) a river provided with prior art transverse groynes.
[0057] FIG. 4 schematically shows the same river as in FIG. 3, FIG. 4 showing the river of FIG. 3 provided with river training structure with a longitudinal groyne according to the invention, FIG. 4A showing a top view and FIG. 4B showing a cross-section of the river.
[0058] FIG. 5 schematically shows the same river as in FIG. 3, FIG. 5 showing the river of FIG. 3 provided with a prior art longitudinal groyne, FIG. 5A showing a top view and FIG. 5B showing a cross-section of the river.
[0059] FIG. 6 shows schematically an Xbloc? as an example of an inter-engaging block which may be used in the invention.
[0060] FIG. 7 shows schematically a Dolos? as an example of an inter-engaging block which may be used in the invention.
[0061] FIG. 8 shows schematically an Accropod? as an example of an inter-engaging block which may be used in the invention.
[0062] FIG. 9 shows schematically a Tetrapod? as an example of an inter-engaging block which may be used in the invention, FIG. 9A showing a side view, FIG. 9B showing a perspective view on the underside of the block of FIG. 9A, and FIG. 9C showing a top view in vertical downward direction on the block of FIG. 9A.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0063] FIG. 1A shows in cross-section the right half of a river with a bottom 4, with a right bank B, and with a transverse groyne TG extending from the bank B to the navigation channel NC. As one can see, in this example the water level WL is at about the crest of the transverse groyne TG. The dam body of the transverse groyne TG is arranged on top of a fascine mattress 6. As can be seen, a part 7 of the fascine mattress 6 extends from the free end 1 of the transverse groyne transverse to the river in the direction of the navigation channel NC. This extending part 7 is part of the end toe construction 2 of the transverse groyne TG.
[0064] FIG. 1B shows the same view as in FIG. 1A, however a longitudinal groyne LG.sub.inv according to the invention has been added. The longitudinal groyne is shown in cross-section, the cross-section being transverse to the longitudinal direction of the longitudinal groyne LG.sub.inv. The longitudinal groyne LG.sub.inv has a longitudinal side 5 facing the navigation channel NC, which side is called the navigation channel side 5. This navigation channel side has a slope S extending under an angle of 45? with respect to the horizontal, i.e. the slope S has a grade of 100%. The longitudinal groyne LG.sub.inv further has as a longitudinal side 6 facing the bank B, which side is called the bank side 6. As one can see in FIG. 1B, the longitudinal groyne LG.sub.inv is located on the edge of the navigation channel C on top of the extending part 7 of the fascine mattress 6.
[0065] FIG. 1C shows the same view as in FIG. 1B after the transverse groyne has been removed. The former transverse groyne is still shown in dashed line.
[0066] FIG. 2 shows a view similar as in FIG. 1C. The difference between FIG. 2 and FIG. 1C is that in FIG. 2 a longitudinal groyne LG.sub.PA according to the prior art has been shown. This prior art longitudinal groyne LG.sub.PA is placed on top of a fascine mattress (not shown) and has a slope with a grade of 30%, corresponding to an angle of about 20? with respect to the horizontal. Due to this small grade, the horizontal width of the prior art longitudinal groyne LG.sub.PA is quite large resulting in the width of the navigation channel being reduced considerably. With the longitudinal groyne LG.sub.inv according to the invention, the width of the navigation channel NC is hardly reduced, as can be seen in FIG. 1C. A further reason why the prior art longitudinal groyne LG.sub.PA is located at quite a distance from the previous transverse groyne TG, is due to the fascine mattress under the prior art longitudinal groyne LG.sub.PA, which projects from both longitudinal sides and is hindered by the previous transverse groyne when this transverse groyne is still present at the moment of building the prior art longitudinal groyne LG.sub.PA.
[0067] FIG. 3 shows a view similar to FIG. 1A. FIG. 3A shows a top view of a river having on both sides transverse groynes extending from the bank to the navigation channel. FIG. 3B shows a schematic cross-section of part of the river, about the part from the free end of one transverse groyne to the free end of an opposing transverse groyne, both free ends being included in the transverse section between the free ends 1 of the transverse groynes. In FIG. 3B the navigation channel NC has been indicated schematically with a dashed rectangle.
[0068] FIG. 4 shows the same views as FIG. 3, however now with a series of two longitudinal groynes LG.sub.inv according to the invention extending over the free ends of the previous transverse groynes at the inside bend of the river, i.e. the transverse groynes at the inside bend of the river have been removed, see FIG. 4A and FIG. 4B. It can be seen that the width of the navigation channel is hardly reduced. With respect to FIG. 4 it is noted, that although the longitudinal groynes LG.sub.inv according to the invention are shown as arranged on the inside bend of the river, arranging longitudinal groynes at the outside bend of the river is in general more efficient with respect to reducing erosion.
[0069] FIG. 5 shows the same views as FIG. 4, however in FIG. 5 a prior art longitudinal groyne LG.sub.PA has been used. As can be seen, both in FIG. 5A and in FIG. 5B, the prior art longitudinal groyne LG.sub.PA reduces the width of the navigation channel considerably for reasons already explained in relation to FIG. 2.
[0070] FIGS. 6-8 schematically show examples of inter-engaging blocks which may be in the river training structure according to the invention.
[0071] FIG. 6 shows a so called Xbloc? 20 which is constituted by a central part 21 and six legs 22-27 extending from the central part such that the central part and legs define a three-dimensional configuration allowing multiple of said blocks to inter-engage each other three-dimensionally when stacked onto each other.
[0072] FIG. 7 shows a so called Dolos? 30 which is constituted by a central part 31 and four legs 32-35 extending from the central part such that the central part and legs define a three-dimensional configuration allowing multiple of said blocks to inter-engage each other three-dimensionally when stacked onto each other.
[0073] FIG. 8 shows a so called Accropod? 40 which is constituted by a central part 41 and six legs 42-47 extending from the central part such that the central part and legs define a three-dimensional configuration allowing multiple of said blocks to inter-engage each other three-dimensionally when stacked onto each other.
[0074] FIG. 9 shows a so called Tetrapod? 50 which is constituted by a central part 51 and four legs 52-55 extending from the central part such that the central part and legs define a three-dimensional configuration allowing multiple of said blocks to inter-engage each other three-dimensionally when stacked onto each other.
