Coastal Interbloc Reinforced Medium Variable Geometry Variable Density Modular Revetment System

The invention relates to a Concrete Armor Block Unit of relatively light weight designed for efficient stacking and transport, connectors, high tensile reinforcing strips, other synthetic materials, in-situ concrete placements and other indigenous materials for use in forming a Structural Revetment system, having any desired setback or no setback which revetment system is designed to resist the erosive forces of the sea, oceans, lakes, and waterways and which revetment system can be configured for placement in a variety of soil conditions to a variety of alignments, curvatures, slopes, aspects, heights and configurations.

The Revetment is an engineered interface which is described as a structural system designed to resist the erosive forces of the sea or to create a controlled interface to preserve the integrity and form of any natural or artificially man-made coastline. Revetments are known to be constructed in various ways, of various materials in various configurations and with varying interface characteristics and objectives.

A rubble mound revetment would usually be sloping, and will comprise large fragments of rock, typically of significant weight, 300 kg to 6.0 tonnes, stacked for stability, and placed on the coastline, to resist and dissipate the erosive forces of the tides, the waves and the currents, by virtue of the mass of the rock fragments, the hardness of the rock, and the voids created by the shape of the rock fragments. Such a sloping rock rubble mound revetment, however, would deny safe or convenient access to the nearshore zone because of the irregularity of the shape and form of the rock fragments; it would not permit intermodal transport of products to the sea from land or to land from the sea, as a result of the turbulence generated as the sea meets the revetment and the danger to damage to the ocean-going cargo vessel. A sheet piled bulkhead is considered as a form of revetment allowing easy intermodal transport by its ease of installation in deep waters so that ocean-going vessels could be accommodated immediately adjacent to solid land.

The INTERBLOC Reinforced Earth Modular Revetment System, the subject of Trinidad & Tobago Patent 49 of 1994 is considered relevant to, but patentably distinguishable from the present invention and is discussed in some detail below. This system was described as a coastal revetment employing a reinforced earth structural mechanism utilizing modular concrete or masonry units interlocked with High Density Polyethylene pins to provide a durable and attractive facing for the resistance of coastal erosion conditions, by way of energy absorbing mechanisms, energy dissipating mechanisms, and for the accommodation of the hydrostatic and hydrodynamic forces associated with the periodic rise and fall of the seas as a result of tidal fluctuation and intermittently as a result of incoming wave action. The following observations are pertinent:

Said INTERBLOC Reinforced Earth Modular Revetment System laid claim of expeditious construction of coastal revetments, construction of coastal bulkheads, quay walls, ship canal walls, marina bulkheads, and other such applications of coastal interface between the sea and the land. The prior art revetment also laid claim of being able to encourage accumulations of sediments at its toe. These claims have been verified. An installation of 141 linear metres of revetment, along Trinidad's Atlantic Coast, was completed in six (6) months and considerable deposits of sediments have accreted at its toe.

Said INTERBLOC Reinforced Earth Modular Revetment System was characterised by having as a “foundation” an in-situ concrete plinth either reinforced or unreinforced. This proved extremely difficult to construct to precise alignment and level in the tidal environment below seabed, requiring a disproportionate length of time before it could be loaded with the INTERBLOC Units, owing to the need for the concrete to attain strength through curing. This is identified as Drawback No 1.

Said INTERBLOC Reinforced Earth Modular Revetment System did not provision adequately for wave overtopping and this is considered a major drawback. Overtopping is the phenomenon which occurs when the combination of wave height, tidal levels and storm surge collectively exceed the like parameters for which a revetment was designed. The run-up height of the wave is therefore greater than the height of the revetment or the crest elevation of the revetment and the waters of the wave surge over the revetment eroding the soil behing the revetment. At least one INTERBLOC revetment structure is known to have failed as a result. This is described as Drawback No 2

The INTERBLOC Reinforced Earth Modular Revetment System was not specific in its description of the strength of concrete to be employed in the manufacture of the INTERBLOC Units, Drawback No 3, nor was it specific in the design strengths and configuration parameters for the high-strength, high density polyethylene soil reinforcing strips, Drawback No 4. Drawback No 3 resulted in accelerated abrasion of the INTERBLOC Units under the impact of sediments in transport as well as splitting of the some INTERBLOC Units in service.

After seventeen (17) years in service, one INTERBLOC Revetment displayed signs of distress, albeit on a miniscule scale (1.773%) of its area; in two locations, the granular free draining material behind the INTERBLOC Units washed out from its location behind the INTERBLOC Units, creating voids, into which the adjacent upper INTERBLOC Units collapsed. Illustration. This absence of adequate detailing of a confining mechanism to keep the free draining material securely in place over time is described as Drawback No 5.

The HDPE connecting pins in several locations, unrestrained vertically, progressed through the receiving pinholes of the INTERBLOC Units, over time, creating a loss of positive connection between concrete units, thereby relying only on the frictional interaction between concrete units to keep the INTERBLOC Units in place. Without precise specification, hollow HDPE Pins were used permitting distortion, and localised collapse of the revetmenmt. This is described as Drawback No 6

The finite thickness (6 mm) of the synthetic soil anchoring strips which anchored the revetment INTERBLOC Units of the revetment facing to the earth on the land side, created a cumulative effect with the stacking of the layers of concrete units which disturbed the geometry of the revetment and reduced the intimate concrete to concrete contact between successive layers of INTERBLOC Units. This is described as Drawback No 7.

A particularly aggressive environment in one location, Roxborough, Tobago, caused the rapid abrasion of the INTERBLOC Units, with aggregate (used in the concrete) being exposed after seven years in service, and significant denudation of the concrete mass of the INTERBLOC Unit thereafter.

Low strength concrete used in the manufacture of the INTERBLOC Units was the cause of this phenomenon. Whilst little attention was paid in Patent No 49 of 1994, to the strength of the concrete of manufacture, evident quality assurance practices (or non-practice) produced a lower strength concrete than was required for the environment also causing cracking of individual units. This detail amplifies on Drawback No 3 already identified above at Page 3 lines 21 to 26.

The lack of rigorous quality control also resulted in INTERBLOC Units of varying thicknesses. Nominal yet meaningful variations in the thickness of adjacent units resulted in less intimate seating of INTERBLOC Units on the units below. The frictional interaction between layers of INTERBLOC Units was adversely affected, contributing to unnecessarily poor aesthetics, manifested in long frequency visual distortions instead of precisely straight lines in the revetment surface. Gaps between upper and lower Units also allowed particulate, vegetative and other matter to be forced between the individual layers of INTERBLOCS by the in-rushing wave energy, again contributing to the poor aesthetics exhibited. This is identified as Drawback No 8.

An exceptionally high storm surge, of some 1.50 metres, the result of Hurricane Lenny in November 1999, caused the sea to overtop an INTERBLOC revetment resulting in washout of the soil used for the reinforced earth backfill, creating a void behind the revetment, into which the revetment facing of INTERBLOC Units collapsed. There was no allowance for rapid drainage of this overtopping flow nor protection against the washout of these materials in the INTERBLOC

Reinforced Earth Modular Revetment. This is identified as Drawback No 9. See also Drawback No 2.

The shape of the prior art INTERBLOC Unit used in the prior art INTERBLOC Reinforced Earth Modular Revetment, did not permit a sufficiently large void porosity in the revetment surface, resulting in larger than necessary wave reflections. This is identified as Drawback No 10.

At revetment locations where there were sudden and large changes in alignment, the ability to effectively maintain the connectivity between adjacent INTERBLOC Units of the prior art and between adjacent layers of said INTERBLOC Units was non-existent. The detailing of these corners led to poor aesthetics, discontinuity, and presented a weak link in the surface concrete matrix, for the forces of the sea to threaten the integrity of the revetment. Whilst the distress caused was considered nominal and localized its aesthetic is unsatisfactory whilst compromising the long term integrity of the revetment. This is deemed a drawback and identified as Drawback No11.

The prior art INTERBLOC Reinforced Earth Modular Revetment, and the current invention, offering aspect slopes ranging from Vertical to 6H:5V, would generally be too steep to provide a stable structure in low bearing capacity sub-soils. Unlike Rubble Mound Revetments, which can be constructed with wide berms, to reduce the effective slope significantly, rendering them applicable in said soft subsoil conditions, the INTERBLOC Reinforced Earth Modular Revetment would precipitate general subgrade rotational failure, if built to its offered slope configurations using all of the materials of the prior art invention. This is identified as Drawback No 12

There is thereby created a need for a Concrete Block Armor Unit and a revetment system which embodies all of the positive and efficient attributes of the INTERBLOC Reinforced Earth Modular Revetment whilst addressing and eliminating the several Drawbacks associated with this embodiment of the prior art; the new Coastal INTERBLOC Reinforced Medium Variable Geometry Variable Density Modular Revetment System, the subject of this application is demed to have the additional attributes of durability, aesthetics, cost-efficieny of transport & storage, ease of assembly, and adaptability to a variety of subsoil conditions, tidal fluctuations, littoral drifts and currents, sediments in transport and wave energies.

The present invention, the Coastal INTERBLOC and the Coastal INTERBLOC Reinforced Medium Variable Geometry Variable Density Modular Revetment System, relates to improvements over the INTERBLOC Reinforced Earth Modular Revetment System, both structural systems specific to the technical field of coastal engineering, and designed to resist the erosive forces of the sea whilst simultaneously ensuring the preservation of integrity and form of any given naturally occurring or artificially built coastline. Developed for long term service as revetments and coastal defences, capable of adaptation to soft seabed soils, capable of withstanding overtopping, this invention represents quantum advances over the prior art, and is now presented.

Disclosed herein are specific configurations of the Coastal INTERBLOC Unit, the non-corrosive connectors called connecting pins being of a specific material of manufacture being High Density Polyethylene (HDPE), a specific configuration of high tensile strength anchoring strip of HDPE and the several other components which can be combined as a revetment having any desired slope created by using any corresponding desired setback from block course to block course. The connector embodiments disclosed herein may be used in a first positioning resulting in no setback between block courses and in a second positioning resulting in a specific setback between Coastal INTERBLOC Unit courses in all situations of revetment construction; subsequent positionings result in a predetermined setback between Coastal INTERBLOC Unit courses and a predetermined slope of revetment. Also disclosed herein are methods of constructing revetments from the Coastal INTERBLOC Units the connectors the high strength tensile soil reinforcing strips and the other components which make up the completed revetment structure.

The invention described herein and below is intended to include all the components and features of Coastal INTERBLOC Reinforced Medium Variable Geometry Variable Density Modular Revetment System including the Coastal INTERBLOC unit, the connectors, high tensile strength anchoring strips, hardwood templates, lightweight concrete blocks, fit for purpose materials, methods of construction which, either alone or in combination, are patentably distinguishable from the prior art. The invention is not intended to be limited to the particular size shape and any other embodiments of the Coastal INTERBLOC unit presented, the material of manufacture, the configuration of soil reinforcing tensile strips, the material of manufacture or the configuration of the connectors or to the order of steps disclosed herein except to the extent that such limitation is explicitly required.

As used herein the terms “the invention”, “the present invention” or “this invention” are intended to refer in a broad manner to all of the subject matter described herein and is not to be limited to the particular embodiments disclosed. In the one embodiment presented of the invention is a method for constructing a revetment from Coastal INTERBLOC Units which includes a plurality of Coastal INTERBLOCS having several vertical holes called pinholes arranged in a predetermined pattern and several larger vertically oriented voids.

The method requires positioning a first plurality of the Coastal INTERBLOCS so as to form at least a portion of a first course of the revetment with the longitudinal spacing of the pinholes in adjacent Coastal INTERBLOC Units being precisely the same as the longitudinal spacing of the pinholes in any one Coastal INTERBLOC Unit and installing at least two connecting pins to each of the first plurality of Coastal INTERBLOCS such that the upper portions of the at least two connecting pins are available to be received in the pinholes of the second plurality of Coastal INTERBLOC Units installed above in such a manner that the any one Coastal INTERBLOC Unit in any upper plurality of Coastal INTERBLOC Units symmetrically straddles two Coastal INTERBLOC Units in the immediate lower plurality of the lower course of Coastal INTERBLOC Units permitting the upper portion of the pins in the two adjacent Coastal INTERBLOC Units in any lower plurality to be accommodated in the two pinholes of any one unit in the immediate upper plurality of Units. The longitudinal spacing of the pinholes herein refers to the orientation along the length of the revetment.

The particular approach disclosed herein for achieving the precise longitudinal spacing of the pinholes in adjacent Coastal INTERBLOC Units in any one course of Units is just one of several approaches which can be used to achieve the objective of the precise spacing of the Units and all of which are covered by this invention.

The preferred embodiments of the invention are described as a Revetment, employing a reinforced medium structural mechanism, utilizing a new Coastal INTERBLOC Unit manufactured of high strength fibre reinforced concrete, the individual concrete units connected with flanged HDPE pins, to provide a durable, attractive, uniform facing for the resistance of coastal erosion conditions by way of energy absorbing mechanisms, energy dissipation mechanisms, and for the accommodation of hydrostatic and hydrodynamic forces associated with the rise and fall of the seas periodically as a result of tidal fluctuation, the intermittent yet relentless impacts of the waves, and the erosive and abrasive forces of the currents and the sediments they transport. These preferred embodiments are equally applicable to oceans, waterways, lakes, rivers, reservoirs and any man made interface between the land and a body of water.

The preferred embodiments of the invention are described as a Revetment, employing a reinforced medium structural mechanism, utilizing a new Coastal INTERBLOC Unit manufactured of high strength fibre reinforced concrete, the individual concrete units connected with flanged HDPE pins, to provide a durable, attractive, uniform facing for the resistance of coastal erosion conditions by way of energy absorbing mechanisms, energy dissipation mechanisms, and for the accommodation of hydrostatic and hydrodynamic forces associated with the rise and fall of the seas periodically as a result of tidal fluctuation, the intermittent yet relentless impacts of the waves, and the erosive and abrasive forces of the currents and the sediments they transport. These preferred embodiments are equally applicable to oceans, waterways, lakes, rivers, reservoirs and any man made interface between the land and a body of water.

The new Coastal INTERBLOC Unit manufactured of concrete, and in this embodiment, of Grade 40 (nominally 6,000 psi) fibre reinforced concrete can be made in either a machine manufacturing dry cast process, using a mould which ensures consistency of dimensioning, over the production of thousands of units or in a wet cast process using continuous steel moulds.

The Machine Manufacturing process vibrates the concrete into the mould, ensuring a dense concrete;

The preferred embodiment of the connecting pins have flanges to arrest the thru passage of the pin through the Coastal INTERBLOC Unit pinholes. If flanges are used, they must reside in circular rebates in the INTERBLOC Unit, so that they do not prevent the Coastal INTERBLOC Unit from making intimate concrete to concrete contact between upper and lower courses of units. The upper half of the HDPE Pin may be tapered to allow expeditious installation of the Unit which straddles the two units below, or it may be right cylindrical. The HDPE Pins may allow a tolerance of up to 5 mm in diameter, between the pin's shaft diameter and the pinhole of the INTERBLOC Unit for ease of assembly, and for inducing long radius curvature in the revetment as and when this is a necessary feature of the revetment alignment.

In summary assessment, the new Coastal INTERBLOC Reinforced Medium Variable Geometry Variable Density Modular Revetment improves upon the earlier INTERBLOC Modular Revetment by virtue of several innovative enhancements in the design, the detailing, the specification and manufacturing processes for its components, in the materials used in its assembly, and the quality assurance stipulations embodied.

It is a system for the construction of revetments which can be expeditiously installed for the prevention of coastal erosion, construction of coastal bulkheads, quay walls, ship canal walls, river channel linings, marina walls, and other such applications of coastal interface between the sea, oceans, rivers, lakes, reservoirs and the land.

It has the capacity to cause sediments to accrete regardless of the direction of flow of the periodic and cyclical littoral drift.

It permits construction over very soft seabed and riverine soils.

It accommodates the occasional combination of high tides, wave energy and surge generated by extraordinary storm condition which would result in wave overtopping without structural distress.

It can be constructed to varying slopes and differing slopes in any one revetment

The present invention, namely the Coastal INTERBLOC and the Coastal INTERBLOC Reinforced Medium Variable Geometry Variable Density Revetment System, comprises the following components:

A confined encased aggregate ‘foundation’ [], [], illustrated at Drawing Sheets Nosand, is the lowest component of the Reinforced Medium Structure, which does not have a ‘Foundation’, per se as the weight of the entire structure, including the exposed surfacing, the reinforcing soils or other medium, is transmitted to the sub-strata over the entire width of the reinforced medium [], []. As such, the preferred embodiment of the starting component of the Coastal INTERBLOC Reinforced Medium Variable Geometry Variable Density Revetment, is a fit-for-purpose bi-axial Geogrid [] or any other high tensile strength mesh medium encasing an aggregate [] to crerate a flexible ‘Foundation’ Mat. The Geogrid [], or any other high tensile strength mesh is a very high strength geo-synthetic, which confines the aggregate particles creating a flexible semi rigid structure. This structure is established at the design formation level for the

Revetment, at a sufficient depth to prevent future undermining by way of scour of the nearshore seabed. This Geogrid Encased Aggregate ‘Foundation’ Mat [], [] replaces the concrete plinth of the prior art invention, thereby addressing Drawback No 1, of the prior art, because of its greater ease and speed of installation, whilst providing the support and positioning for the first plurality or course of Coastal INTERBLOC Units [] immediately upon completion of installation in any tidal window. The aggregate used in this component need not be the highest quality, as it is not subject to the abrasive forces of the water, buried as it is, in service, beneath the seabed. Meaningful cost savings over the earlier approach disclosed in the prior art, with increased ease of installation and no loss of functionality render this approach superior to the prior art in every respect.

The hardwood alignment and levelling template [], illustrated at Dwg. Sheet No 14, also addresses Drawback No 1, permitting installation of the first courses of the new Coastal INTERBLOC Reinforced Medium Variable Geometry Variable Density Revetment below seabed elevation, usually below the water line, rapidly. Whilst coffer-damming and pumping will facilitate this operation, taking advantage of a low tidal window, the hours immediately before and after the low tide, will allow substantial cost savings. The preferred embodiment of the hardwood alignment and levelling template [], chosen as it is heavier than water, facilitates the rapid installation of the first plurality or course of Coastal INTERBLOC Units [] at a precise grade and to the precise spacing of the Units, which is required, to enable the rapid placement of subsequent layers of Coastal INTERBLOC Units []. The hardwood used must be heavier than water so that it will not float during its placement before it is locked in place by the weight of the Coastal INTERBLOC Units []; Green Heart is one such hardwood and is not known to be affected by any type of marine borers nor is it susceptible to marine rot. The hardwood alignment and levelling templatewhen placed on the geogrid encased aggregate foundatiion [], [], described above, can be very easily levelled, and set to the design alignment, including curvilinear alignments if necessary with short chords, thereby fixing in perpetuity the alignment and elevation of the Revetment toe, and consequently the alignment of the revetment itself.

This hardwood alignment and levelling template [] can be of any length, limited only by the available lengths of source material, with the optimum length being 3.0 metres, permitting curvatures to be introduced in the revetment based on 3.0 m long (or any specified length) chords.

The preferred embodiment of the hardwood alignment and levelling template [] presented herein measures in cross section 200 mm×50 mm, providing the requisite section modulus to resist deformation under loading. The particular approach disclosed herein for achieving the precise longitudinal spacing of the pinholes [], [], [], [], [], [], in adjacent INTERBLOC Units [] in any one course of Units is just one of several approaches which can be used to achieve the objective of the precise amd rapid spacing of the Units and all of which are covered by this invention.

A Coastal INTERBLOC Unit [] in any course straddles the two Coastal INTERBLOC Units [] in the course immediately below, and it is of mandatory absolute importance, that the longitudinal spacing of the pinholes [], [], of two adjacent (side by side) Coastal INTERBLOC Units, is precisely equal to the longitudinal spacing of the pinholes [], [], of the one upper unit which will straddle the two lower units. The hardwood alignment and levelling template [] is machined from a cured hardwood plank, drilled with a row of blind holes [] at a longitudinal spacing which is exactly equal to the pinhole spacing of the Coastal INTERBLOC Unit, each hole of diameter equal to that of the locating pin [] lower sector.

Locating Pins [], placed in blind holes [] of the alignment and levelling template are used to precisely locate the first course of Coastal INTERBLOC Units [] in the assembly. Locating Pins [] are placed in the blind holes [] of the alignment and levelling template with snug fit. INTERBLOC Units [] are then positioned so that the exposed upper sector of the pins occupy the Pinholes [], [], in the Unit, enabling the rapid placement of the first course of Units, during the Low Tidal Window. In the embodiment presented of the invention is a method for constructing a revetment from a plurality of INTERBLOC Units [] having several smaller vertical holes called Pinholes arranged in a predetermined pattern and several larger vertically oriented voids. The method includes positioning the first plurality of the Coastal INTERBLOC Units [] so as to form at least a portion of a first course of the revetment with the longitudinal spacing of the pinholes in adjacent Units being precisely the same as the longitudinal spacing of the pinholes in any one Unit [] and installing at least two connecting pins [] are available to be received in the pinholes of the second plurality of Units installed abovein such a manner that the any one Unit in any upper plurality of Coastal INTERBLOC Units symmetrically straddles two Coastal INTERBLOC Units in the immediate lower plurality of Coastal INTERBLOC Units permitting the upper portion of the connecting pins in the two adjacent Coastal INTERBLOC Units in any lower plurality to be accommodated in the two pinholes of any one unit in the immediate upper plurality of Coastal INTERBLOC Units. The longitudinal spacing of the pins and the pinholes herein refers to the orientation along the length of the revetment. A spacing tool illustrated at Drawing Sheets 17 and 18, comprising steel pins of like diameter to the pinholes affixed to a rigid steel plate and spaced with the exact spacing of the pinholes is employed to attain the exact spacing of the pinholes in adjacent Coastal INTERBLOC Units being the preferred method of attaining the exact spacing of the pinholes as required.

The Coastal INTERBLOC Unit, Model 36-L, Scale 1.0 refers to one possible embodiment of the current invention, in which the Scale 1.0 determines the primary dimensions of this Coastal INTERBLOC Unit presented, being nominally, 577 mm×318 mm×170 mm thick and weighing 50.20 kilograms (Kg), the threshold for installation using human effort only. See Drawing Sheets Nos 1, 2 & 3. Other embodiments of the current invention permit smaller and larger scales all of which scales and dimensions are considered covered by this current invention.

The embodiments presented and called Model 36-L permits revetments constructed with attack slopes of Vertical, 3 Horizontal to 5 Vertical (3H: 5V), and 6H: 5V. The L in the designation represents the embodiment required to intercept the predominant littoral current flowing from left to right when facing the ocean, to maximize the accretions of sediments in suspension. Another embodiment called 24-L is the alpha numeric designation assigned to a specific Unit design which permits construction at slopes of Vertical, 2H: 5V, and 4H: 5V, for use in environments where the predominant littoral current flows from left to right. Variations in the thickness of a Coastal INTERBLOC Unit, (200 mm for the 24-L vs 170 mm of the 36-L), in the transverse pinhole spacing (80 mm vs 102 mm, measured perpendicular to the revetment alignment), overall length (516 mm vs 577 mm) and weight (51.6 Kg vs 50.2 Kg) distinguish the Model 24-L Unit from the Model 36-L. Models 36-R (Right), and 24-R are alphanumeric designations which are self-explanatory. See Drawing Sheet 26.

The new Coastal INTERBLOC Unit is specifically engineered with the varying model configurations being purpose built, not simply inverted, or sloped at the formation, to achieve a desired revetment aspect and aesthetic. The several models possible of the Coastal INTERBLOC Unit are numerous, functions of the unit thickness, the pinhole transverse and longitudinal spacings, angles of the Coastal INTERBLOC Unit faces, and are all considered to be covered by this invention.

The Coastal INTERBLOC Unit presented in this patent application represents a complete re-engineering with respect to the prior art for:

A typical Coastal INTERBLOC Unit, the Model 36-L, Scale 1.0, is presented at Drawing Sheet No. It has a size and weight which permits expeditious assembly by manual unskilled labour, it has frontal faces [], [], [] which absorb wave impact, by permitting the smooth flow of water of the incident wave around its contours into the void [] behind, which void [] exists by virtue of the Unit's.