Patent Grant
9797106
The present invention relates in general to revetment blocks, and more particularly to revetment blocks and methods of installing such blocks on a levee to reduce the energy of surge water flowing over the levee.
Revetment blocks are available in many different shapes and sizes to accommodate different situations to control the erosion of soil. Revetment blocks can be constructed with arms and sockets that interengage together, but are not positively interlocking to prevent lateral separation of neighbor blocks interlocked together. Other revetment blocks have positive interlocking arms and sockets so that when installed in an interlocking manner, the blocks cannot be laterally removed from each other, thereby allowing heavy water flows thereover without dislodging any of the blocks. Such a revetment block is disclosed in U.S. Pat. No. 5,556,228 by Smith.
In order to prevent erosion of the soil in a waterway, revetment blocks are installed as a mat to cover the entire area to be protected from erosion. This often involves lining the bottom and sides of the waterway with revetment blocks so that the water flows over the revetment blocks and the underlying soil is protected from erosion. The particular type of revetment block can be selected based on the velocity and the volume of water that is expected to flow down the waterway. Engineers and hydraulic specialists can determine what style of revetment block is best adapted for these conditions.
Additional conditions taken into consideration is the direction of water flow in the channel or waterway. Since the direction of the flow of water is generally in the same direction, this is usually not a variable that must be considered. However, certain revetment blocks are constructed to control various aspects of the water flow, and thus such blocks must be installed in a certain orientation in order to assure that the water reacts in the proper way when flowing over the blocks. For example, U.S. Pat. No. 8,678,704 by Smith discloses a tapered top revetment block that is installed in a waterway in a certain orientation so that the tapered top tapers upwardly in a downstream direction to reduce the lifting force exerted on the mat of blocks and thus increases the factor of safety. U.S. Pat. No. 8,123,434 by Smith discloses a mat of interlocking revetment blocks where certain blocks of the mat have different heights to thereby form interruptions in the flow of water and create turbulence to slow down the velocity of the water. In other words, by using different height blocks in the mat, the roughness coefficient of the mat is increased, thus slowing down the velocity of the water flowing thereover. The roughness coefficient of a mat of revetment blocks is also known as “Mannings N.”
A field of concern that has not been addressed in terms of water control is that of wave surges during times when higher than usual waves surge over areas that are usually not protected from erosion. For example, wave surges can be experienced during hurricanes, tidal waves, tsunamis, etc., where the surges of waves flow over dams, levees and the like. The hurricane Katrina hit the New Orleans area and breached many of the levees to the extent that the levees no longer protected the land side. Since the landside of the levees generally did not experience water flow, there was often no protection on such side of the levee, except that which was necessary to prevent erosion of the levee during heavy rainfalls. Often the river side of the levee was protected from erosion as that side of the levee experiences water flow in the downstream direction during flooding of the river.
When a levee experiences a storm surge, the waves can be sufficiently high as to flow over the levee and erode the backside of the levee, thereby reducing its strength and integrity. The wave surges are often caused by high winds. If the erosion on the backside of the levee continues, the levee can be breached so that water flow in either direction through the hole in the levee is possible, and flooding of the land side of the levee can occur. Moreover, as the wave surge flows over the levee, it speeds up as it flows down the incline on the land side of the levee, thereby accelerating soil erosion on the backside of the levee.
From the foregoing, it can be seen that a need exists for a technique to protect levees, and the like, from storm surges not only on the front side, but also on the backside or land side of the levee. A further need exists for a method of installing revetment blocks on the land side of a levee to slow down the velocity and energy of water and reduce the kinetic energy thereof as a wave surges over the levee. Another need exists for a method of protecting the land side of levees from erosion as well as controlling the energy of water flowing down the land side of the levee to reduce the destructive force of the water.
In accordance with an important feature of the invention, disclosed is revetment block that is constructed with a tapered top surface, where the taper terminated in a downward transition edge. When a number of the tapered top revetment blocks are installed as a mat over a surface of the levee, the flowing water encounters the many transition edges and reduces the energy of the water, thus minimizing the damaging effects of water as it surges over the levee.
The tapered top revetment blocks are particularly advantageous when installed on the land side of a levee so that water surges over the levee not only protect the ground on the land side, but also slow down the velocity of the water flowing down the land side of the levee. The roughened surface of the mat of revetment blocks occasioned by the many upwardly projecting transition edges, slows down the surge water and causes less damage to buildings and structures located on the land side of the levee.
The tapered top revetment blocks are preferably constructed with positive interlocking arms and sockets, although this type of engagement between neighbor blocks of a mat is not a necessity. The upstream and downstream arms or sockets of each revetment block can also be tapered in the same manner as the top surfaces of the blocks. The side edge arms and sockets of each block can also be tapered in the same manner as the top surface.
The tapered top revetment blocks can be installed in the same orientation on the water side of a levee, over the crest and on the land side of the levee to reduce the energy of water surging over the levee. Alternatively, the tapered top revetment blocks can be installed on the water side of the levee in a reverse orientation so as to be rotated 180 degrees, as compared to the tapered top revetment blocks installed on the land side of the levee. In this latter alternative, interface blocks on the crest of the levee can be utilized to mate the edge of the water side mat to the edge of the land side mat. In this alternative arrangement, the surge water that does not flow over the crest of the levee is reduced in energy as it flows back down the water side of the levee.
In accordance with an embodiment of the invention, disclosed is a method of controlling water flow over a levee having a water side and a land side. The method of this embodiment includes lining the land side of the levee with a mat of revetment blocks, where each revetment block has a frontal edge into which the water flowing down the levee on the water side abuts to thereby reduce the energy of the water. The revetment blocks are situated so that the respective frontal edges of the revetment blocks extend vertically above a downstream end of a similarly-constructed upstream neighbor revetment block.
According to another embodiment of the invention, disclosed is a method of controlling water flow over a levee having a crest located between a water side and a land side. The method of this embodiment includes installing a mat of revetment blocks on the land side of the levee from the crest of the levee to a downhill portion. The revetment blocks each have a tapered top surface tapering upwardly from a downstream end to an upstream end. The tapered top revetment blocks are installed so that a thicker end of each said revetment block is laid uphill and a thinner end of each said revetment block is laid downhill, so that a vertical transition edge is formed between neighbor revetment blocks. The transition edges of the revetment bocks are used to reduce the energy of the water flowing over the levee and down the land side thereof.
According to yet another embodiment of the invention, disclosed is a method of controlling water flow over a levee having a crest located between a water side and a land side. The method of this embodiment includes using revetment blocks having tapered top surfaces, where each of the tapered surfaces terminates in an abrupt downward transition edge. The tapered top revetment blocks are installed on the water side of the levee so that water returning downhill on the water side of the levee encounters the abrupt transition edges and slows the downhill flowing water down. The tapered top revetment blocks are also installed on the land side of the levee so that water flowing over the crest and downhill on the water side of the levee encounters the abrupt transition edges and slows down the water flowing downhill on the land side of the levee.
Further features and advantages will become apparent from the following and more particular description of the preferred and other embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters generally refer to the same parts, functions or elements throughout the views, and in which:
With reference to
The arms and sockets of the block 10 allow a positive lateral interlock between each of the four neighbor blocks. With positive interlocking erosion control blocks, the advantage is that the hydraulic force of surging water cannot move the blocks laterally when they are interlocked together. The only way for a positive interlocking revetment block to be dislodged from the matrix is to be lifted vertically out of its interlocking engagement with the four neighbor blocks. The tapered top interlocking revetment blocks 10 can be installed on top of a woven or non-woven geotextile material covering the area to be protected from erosion.
In accordance with a feature of the tapered top interlocking revetment block 10, when the underlying ground becomes uneven or irregular, due to removal of soil, settling, or the like, the factor of safety of the mat is not compromised and thus the integrity thereof is maintained for longer periods of time and under more adverse conditions. The revetment block 10 includes a tapered or slanted top surface, a level bottom surface and interlocking arms and sockets. The revetment block 10 thus includes a thicker upstream portion and a thinner downstream portion. The revetment block 10 is installed with the thinner portion downstream (direction of arrow 12), and the thicker portion upstream. In accordance with the invention, the revetment block 10, and other similar blocks 10 forming the mat, include a downstream thinner portion and a thicker upstream portion. The tapered top revetment block 10 provides controlled hydraulic performance as the water flows over a levee, embankment, or similar barrier.
Each tapered top revetment block 10 includes an upstream arm 14 that fits into a socket 30 of the similarly-constructed upstream block. The block 10 is constructed with a downstream socket 30 into which the arm of a similarly-constructed downstream block fits. The positive interlocking arms and sockets will be described in more detail below. The revetment block 10 is constructed with other corresponding side arms and sockets that fit into the respective side sockets and arms of similarly-constructed neighbor blocks located on each side (not shown) of the revetment block 10. As can be appreciated, the water flowing downstream over the mat or blanket of tapered top revetment blocks 10 encounters an abrupt vertical transition edge of each of the blocks, thus creating turbulence and slowing down the velocity of the surge of water.
In the event that the underlying surface of the ground becomes irregular, the thinner downstream portion of the block raises to accommodate the ground irregularity. However, even when the thinner downstream portion of block 10 is lifted, there still exists a portion of an abrupt vertical transition edge which the flowing water encounters to reduce the velocity of the water. This is because the top of the downstream thinner portion may still not be above the thicker upstream portion of the neighbor downstream block 10. It can be seen that if the difference in the thickness between the thinner downstream portion and the thicker upstream portion is, for example 0.5 inch, then the ground irregularity can be up to 0.5 inch before the factor of safety of the block begins to be affected.
The tapered top revetment block 10 is constructed so that when the arms are interlocked within sockets of neighbor blocks, there is still sufficient articulation between blocks to accommodate ground contours normally encountered or expected. As can be further appreciated, the difference in thickness of each of the tapered top revetment blocks 10 can be determined or engineered as a function of the unevenness of the ground on which the blocks are to be installed. Thus, for each different installation, the blocks 10 can be engineered to guarantee a specified factor of safety as a function of the unevenness of the ground. In addition, for ground characteristics that change over time, the revetment blocks 10 can be initially constructed to provide a factor of safety based on the expected change over time. As noted above, a difference in the ground surface of about 0.5 inch is an industry standard by which factors of safety are determined.
In the event that the ground changes such that a bump is formed under the thicker upstream portion of the revetment block 10, then more of the vertical face of the block 10 will be exposed, thus facilitating the control of the water by slowing it down.
With reference again to
The tapered top block 10 is constructed with an upstream arm 14 that includes a top surface 24 that is tapered with the same angle as the top surface 16 of the block 10. The upstream arm 14 includes an enlarged part 26 connected to the side edge of the block 10 by a narrowed portion 28. The downstream end 22 of the block 10 includes a socket 30 having a narrowed inlet 32 formed into the body of the block 10. A similar side socket 34 is formed in an adjacent side of the base block 10. A side arm 36 is formed in the block 10 opposite the side socket 34. Thus, there is a respective socket formed in the side of the block 10 opposite each arm. The upstream arm 14 of the revetment block 10 fits within a socket of a similarly-constructed upstream neighbor revetment block 10′. The downstream socket 30 receives therein an upstream arm of a similarly-constructed downstream neighbor revetment block. The side socket 34 of the block 10 receives therein a side arm of a similarly-constructed neighbor block. Lastly, the side arm 36 of the block 10 fits within a side socket of a similarly-constructed neighbor block. As can be appreciated, the tapered top revetment block 10, as well as the four similarly-constructed neighbor blocks, are installed by lowering the blocks down into the arms/sockets of the neighbor block(s). As such, the revetment blocks 10 of the mat cannot be removed by lateral movement, but only by lifting the blocks vertically out of positive interlocking engagement with the neighbor blocks.
As noted above, the top surface 16 of the block 10 is tapered downwardly from the upstream end 20 to the downstream end 22 thereof. The upstream end 20 of the tapered top surface 16 includes a discontinuity or transition edge 40 that rises abruptly about 0.5 inch to the beginning of the tapered top surface 16. The upstream arm 14 is also tapered downwardly toward the transition edge 40 with the same angle as the slope of the top surface 16. Moreover, the change in thickness in the upstream arm 14 is the same as that of the downstream socket 30 so that when the upstream arm 14 of the tapered top block 10 is engaged within the downstream socket of the neighbor block, a uniform tapered surface between the two engaged blocks is achieved. The degree of taper in the top surfaces of the blocks 10 can be different from that described above.
In the preferred embodiment, the tapered top block 10 is constructed by forming five holes therethrough from the top surface 16 to the bottom surface 18. The holes function to allow vegetation to grow therein and assist in anchoring the block 10 to the underlying ground of the land side of a levee. The specific spacing and hole size can also improve the hydraulic characteristics of the block 10. There are four holes 50, 52, 54 and 56 formed in the respective corners of a virtual square. A fifth hole 58 is formed in the middle of the virtual square. The diameter of each hole is about 2.0 inches, and the center of each of the four holes 50, 52, 54 and 56 is about 4.0 inches from the center of the central hole 58. The holes can be formed with different sizes and at different locations in the block according to the description of U.S. Pat. No. 8,123,435 entitled “Interlocking Revetment Block With Array of Vegetation Holes.”
According to an important feature of the invention, the tapered top revetment blocks 10 are installed on the water side of the levee 60, over the crest or top of the levee 60, and back down the land side of the levee 60. The tapered top revetment blocks 10 are installed in an orientation so that the abrupt transition edge 40 is exposed and faces the oncoming water flow. When each revetment block 10 is installed and interlocked in this manner, the abrupt transition edge 40 of each tapered top revetment block 10 presents an interruption to the laminar flow of water over the mat of revetment blocks 10. As the water flows over the tapered surface of each revetment block 10, it hits the abrupt transition edge 40 and thus turn upwardly into a turbulent flow, thus slowing the water velocity down. The upward turbulent flow of water at each abrupt transition edge 40 of the mat of blocks 10 creates turbulence in the other water flow in the vicinity to thus slow it down also. As such, the overall effect of the tapered top revetment blocks 10 installed in this orientation increases the roughness coefficient (Mannings N) and slows down the water flow and reduces the destructive effect of surges of water over the levee 60.
It has come to be appreciated that levees 60 are breached when wave surges 62 flow over the levee 60 at short intervals of time. When the surge 62 of water comes over the crest of the levee 60, it runs down the land side and otherwise picks up speed as it flows downhill. The surge 62 of water which already has significant velocity increases in velocity as it runs down the downhill side of the levee 60. The destructive force of the wave surge 62 is thus increased as it runs over the downhill side of the levee 60. When there is insufficient erosion protection of the levee 60 on the land side thereof, then the soil is carried away by the wave surge 62 and compromises the integrity of the levee 60. When a sufficient amount of the levee 60 has been eroded, then a portion of the levee 60 can collapse and allow the wave surges 62 to flow through the breach in the levee 60 and cause heavy flood damage to buildings on the land side of the levee 60.
It can be appreciated that by lining the land side of levees 60 with interlocking revetment blocks, the underlying soil is protected from erosion. The integrity of the levee 60 is thus maintained when surges 62 exceed the height of the levee 60. In addition, when tapered top revetment blocks 10 are utilized in lining the land side of a levee 60, the abrupt transition edge 40 of each block 10 has the effect of slowing down the velocity of the water surge 62 to thereby reduce its energy and the destructive force thereof. While not shown, the land side of the levee 60 can be lined with the tapered top revetment blocks 10 even where the ground levels out to the natural elevation. The tapered top revetment blocks 10 on the level area of the land side of the levee 60 function to continue reducing the velocity and energy of the wave surges 62.
With reference again to
It can be appreciated that a wave surge 62 can cause damage on the land side of the levee 60 by several means. One, the water 62 can flow on the land side of the levee 60 and flood buildings, vehicles, etc. In other words, the water can rise to a level on the land side of the levee 60 so that buildings, dwellings, vehicles, etc., are filled with water and corresponding damage is caused. Secondly, if the wave surges 62 have sufficient velocity and energy when flowing on the land side of the levee 60, the energy of the wave surges 62 may not only flood buildings and dwellings, but also destroy them by breaking walls so that the buildings are leveled and no longer exist. Indeed, high energy wave surges 62 can carry the resulting debris, vehicles, and other loose materials downstream to cause additional and collateral damage. When vehicles are carried downstream by a surge 62 of water, the vehicles can function as projectiles and ram buildings and bridges and cause additional damage. Thus, if only the tapered top revetment blocks 10 cause the wave surge 62 to slow down, the corresponding destruction of buildings and dwellings will be reduced, even if flooding still exists.
The wave action of the surging water 62 on the water side of a levee 60 is up and down the sloped side, until the wave has gained sufficient energy to flow over the top of the levee 60. This up and down wave action is illustrated as arrow 64 in
When installing the tapered top revetment blocks 10 in the manner illustrated in
With reference back to
The double taper top revetment block 80 is constructed with an arm 82 extending from a side of the body of the block 80 and a socket 84 formed in the opposite side of the revetment block 80. Otherwise, the arms and sockets of the block 80 are similar to that shown in
While the preferred and other embodiments of the invention have been disclosed with reference to specific revetment blocks, and associated methods of fabrication and installation thereof, it is to be understood that many changes in detail may be made as a matter of engineering choices without departing from the spirit and scope of the invention, as defined by the appended claims.
This U.S. non-provisional patent application claims the benefit of U.S. provisional application Ser. No. 62/123,094, filed Nov. 6, 2014.
| Number | Name | Date | Kind |
|---|---|---|---|
| 1164707 | Edinger | Dec 1915 | A |
| 1164708 | Edinger | Dec 1915 | A |
| 1561796 | Rehbock | Nov 1925 | A |
| 2171560 | Holmes et al. | Sep 1939 | A |
| 3347048 | Brown et al. | Oct 1967 | A |
| 3854291 | Perkins | Dec 1974 | A |
| 4269537 | O'Neill | May 1981 | A |
| 4279536 | Jarlan | Jul 1981 | A |
| 4352593 | Iskra et al. | Oct 1982 | A |
| 4465398 | Knudsen | Aug 1984 | A |
| 4781492 | Shindo | Nov 1988 | A |
| 4813812 | Hasegawa et al. | Mar 1989 | A |
| 4856934 | Nelson | Aug 1989 | A |
| 4875803 | Scales | Oct 1989 | A |
| 4978247 | Lenson | Dec 1990 | A |
| 5020938 | Scales | Jun 1991 | A |
| 5544973 | Frizell et al. | Aug 1996 | A |
| 5556228 | Smith | Sep 1996 | A |
| 6079902 | Pettee, Jr. | Jun 2000 | A |
| 6267533 | Bourg | Jul 2001 | B1 |
| 6276870 | Smith | Aug 2001 | B1 |
| 6508607 | Smith et al. | Jan 2003 | B1 |
| 6955500 | Smith et al. | Oct 2005 | B1 |
| 7037037 | Smith et al. | May 2006 | B1 |
| 7717643 | Han | May 2010 | B2 |
| 8123434 | Smith | Feb 2012 | B1 |
| 8123435 | DeShaw et al. | Feb 2012 | B1 |
| 8678704 | Smith et al. | Mar 2014 | B1 |
| 8678705 | Smith et al. | Mar 2014 | B1 |
| Number | Date | Country |
|---|---|---|
| 04024310 | Jan 1992 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 62123094 | Nov 2014 | US |
