Edgedrain

Field of the Invention

This invention relates to a hydraulic drain, and more particularly to a flat tubular structure which can be used as a highway edgedrain.

Background of the Invention

This invention is directed to the providing of a suitable hydraulic structure which is designed to be utilized as a highway edgedrain. The presence of water in the road sub-base aggravates the deterioration of the highway. In the case of flexible pavement systems, such as asphalt, some of the distresses related to water include potholes, loss of aggregates, raveling, weathering, cracking, and heaves (from frost or swelling soils). For rigid pavement systems, such as concrete, some of the distresses include faulting, joint failure, various type of cracking, blow-up or buckling, curling, surface spalling, steel corrosion, and heaving (from frost or swelling soils).

Moisture may enter and saturate pavement systems in several ways, including surface moisture and rising water tables. After the highway base becomes saturated, passage of vehicles causes a pumping action, which in turn causes displacement of supporting particles beneath the highway and weakening of the structure.

Various types of drains and drain systems are shown U.S. patent nos. 3,563,038, 3,6544,765, 3,699,684, 3,830,373, 4,572,700, French patent no. 2,384,901 and U.K. patent no. 2,056,236. Many drain structures are difficult or expensive to install, or difficult to transport. Other problems with these prior proposals include insufficient structural rigidity, clogging and dimensional creep.

Summary of the Invention

In accordance with this invention, a hydraulic structure is provided for use preferably as an edge­drain, especially suitable for highways. The structure of this invention is formed from an oblongated plastic core or shell that can be fabricated in a thickness suitable for attaining the necessary structural strength. The plastic core is configured as a rela­tively flat tube and inserted into a porous fabric sheath. Preferably, this fabric sheath is a nonwoven fabric. The plastic core is corrugated, with a plurality of apertures present in the grooves associated with the corrugation. The recessed grooves act as channels to rapidly accommodate any water excreted by the adjacent sub-base, while the flat surface of the ridges approximates a planar exterior surface which supports the fabric sheath away from the apertures in the grooves.

Additionally, a plurality of supports extend between the flat walls of the tube to prevent collapse of the tube, and to minimize creeping problems. These supports may take the form of opposed cuspations in the walls. At the same time, long lengths of the drain may by coiled for easy transportation and installation.

Description Of The Drawing Figures

• Figure 1 is a fragmentary front perspective view of the hydraulic structure with a portion of the sheath shown removed.
• Figure 2 is a diagrammatic drawing showing the sources of water in roadbeds.
• Figure 3 is a diagrammatic drawing showing the effect of pumping action on a roadbed.
• Figure 4 is a sectional view of a roadbed, showing installation of the drain.
• Figure 5 is a fragmentary side view of the preferred embodiment of the invention.
• Figure 6 is a vertical sectional view on an enlarged scale taken along line 6-6 of Figure 5.
• Figure 7 is a vertical sectional view on an enlarged scale taken along line 7-7 of Figure 5.
• Figure 8 is a fragmentary side view of a modified structure of the invention.
• Figure 9 is a fragmentary side view on a greatly enlarged scale showing the area enclosed by line 9-9 of Figure 8.
• Figure 10 is a vertical sectional view on a greatly enlarged scale taken along line 10-10 of Figure 8.
• Figure 11 is a fragmentary horizontal sectional view taken along line 11-11 of Figure 9.

Description Of The Illustrative Embodiment

Figure 2 illustrates a highway 25 surrounded on three sides by subgrade soil 27, and a ground water table 28 at some depth below the highway. Water problems occur beneath the highway due to three sources of water designated as W-1, W-2 and W-3. Some water will rise from ground water table 28 by means of capillary action as shown by W-1. Rain water will pass into the subgrade soil beneath highway 25 by means of lateral seepage as shown by W-2. Finally, some water will seep through cracks and joints in highway 25 and enter the subgrade soil as shown by W-3.

Figure 3 shows the effect of a heavy vehicle on the highway 25 and the highway pavement 30 and sub-base 31. The weight of vehicle V moving in direction T will depress portions of the pavement wherever there is a fault 33 or cavity 34. The depression of the pavement along fault line 33 causes some deterioration of the pavement surface. However, the major damage to the road is caused by the underlying effect of water as shown by water movement W-5, W-6 and W-7. Water is forced downwardly through the sub-base towards the subgrade soil. Additionally, water is forced laterally in direction W-6 parallel to the road surface. Other water is forced in direction W-7, filling cavity 34 and eroding small particles from the lower surface of pavement 30.

As vehicle V travels in direction T across fault line 33, a portion of the pavement previously depressed returns towards its original position, while the portion of the pavement immediately beyond the fault line now becomes depressed as shown in the lower portion of Figure 3. Water previously directed downward by force W-­5 is subjected to extreme downward pressure which over time results in the creation of a depression 35. This depression allows portions of sub-base 31 to pull away from the lower surface of pavement 30, thereby causing a greater volume to be associated with cavity 34. Additional water force is directed into the portion of the cavity formerly filled by the depressed pavement. This force of water W-8 causes additional fine particles on the lower surface of the pavement to erode. The rapid contraction of cavity 34 by the passage over fault 33 of vehicle V will force water to spurt upwardly through the fault as shown by W-9. This rapid expulsion of water will be accompanied by particles originating from the pavement, as well as sub-base sediment.

In accordance with this invention, an edgedrain 20 is designed to be positioned immediately adjacent the edge of pavement 30 and sub-base 31 as shown in Figure 4. Normally the pavement itself is approximately 9 inches thick with the sub-base being approximately 10 inches thick. The sub-base may be of a single material or may have the upper portion comprised of an aggregate bituminous base with the lower portion comprised of a lime sub-base. The edgedrain 20 is positioned in trench 42 such that its lowermost portion is a minimum of between 16 and 22 inches below the surface. Similarly, the edgedrain preferably extends between 1-1/2 and 2 inches above the seam line associated with the pavement 30 and sub-base 31. Trench 42 then has fill 43 deposited on the opposite side of edgedrain 20 to ensure that the edgedrain is in intimate contact with the edge of the pavement and sub-base. Finally, a concrete, asphalt, or other aggregate cap 45 may be placed along the length of the top of the trench.

As shown in Figure 1, the drain has an external core 50 in the form of a longitudinally flexible corrugated tube encased in a porous fibrous sheath or web 52. Preferably, the tube is formed from extruded thermoplastic polymer such as polyethylene fabricated in a thickness suitable for obtaining necessary structural strength. A suitable wall thickness is between .03 and .04 inches. The fibrous sheath 52 preferably is of a nonwoven fabric wrap of a geotextile composition having a density of at least 3 ounces per square yard, similar to the products known as TYPAR or REEMAY.

The corrugated structure of the tube can best be seen in Figures 5, 8 and 9, which show the various ridges 54 and grooves 55 associated with the corruga­tion. The ridges and grooves appear as alternating annular peaks and valleys with walls interconnecting them. In selected valleys 55 of the tube, a plurality of apertures 58 are arranged transversely to the longitudinal axis of the tube. Additionally, the apertures are arranged in a plurality of rows with respect to the longitudinal axis of the tube.

A plurality of supports or cuspations 60 project inwardly from opposite first and second flat side panels 66 and 67 respectively. These cuspations serve as a means which extend between the side panels to provide internal support between the walls. The panels, along with rounded edges 68 and 69, provide the tube with an oblongate cross-sectional appearance as can be seen in Figure 1. In the preferred embodiment shown in Figures 5-7, the cuspations are of two types. The first type of cuspations 80 are positioned along the longitudinal axis of the structure, and are of a polyhedral shape with a plurality of triangular faces 81. The base of the polyhedron is preferably a square with sides of a length of 1-1/8 inch. Opposing cuspations are physically joined to one another at mold line 82, so as to secure panels 66 and 67 in fixed spatial relation to each other. The cuspations 80 project approximately 3/8 inch inwardly from the interior surface of each of said panels 66 and 67.

A second type of cuspation 85 may be employed, which has the appearance of a truncated polyhedral shape, with the truncation preventing the opposing cuspations of this second type from being secured to one another. The ratio of the number of this second type of cuspation to the first type is at least 2:1. At least one row of the second type of cuspation appears between the edges 68 and 69 and the center row of cuspations 80. Cuspations of this second type 85 can also be positioned along the longitudinal axis of the structure, being interspersed with cuspations of the first type 80. The tube is thus coilable about the axis parallel to the corruga- tions. Moreover, the structure is structurally continuous and rigid in directions perpendicular to the longitudinal axis.

In the alternative embodiment, shown in Figures 8-­11, there are fewer rows of cuspations, with all of the cuspations resembling one another. Figures 8-11 show all cuspations as being the first type. Al of these cuspations are shown as being positioned in opposing relationship.

In both embodiments, the means of support 60 are provided at intervals along the length of the tube. The cuspations 60 are oriented such that the two panels have an identical number of cuspations occurring in pairs, preferably located opposite one another.

As can be seen in Figure 8, the ridges or annular peaks and grooves or valleys alternate with one another will walls interconnecting said peaks and valleys. In the preferred embodiment of the invention, the annular peaks are of a height of approximately 3/8 inch and are in the shape of a trapezoid. The upper surfaces of the peaks are flat such that panels 66 and 67 assume a relatively flat configuration. The dimensions associated with the width of the valleys is approximately the same as the dimensions associated with the width of the peaks. These alternating peaks and valleys form a plurality of channels for receiving and transporting of fluids to the apertures at which locations the flow enters the interior of the tube and passes along a plastic lined flow channel forward in part by the inner surface wall of the tube. The peaks also serve to keep the fabric sheath in a spaced relation with the bottom of the channels and the apertures therein.

As can be seen in Figures 1 and 7, the first and second panels are secured to one another along the top and bottom of said panels throughout their entire length with said fibrous sheath being secured to itself by appropriate fastening means such as ultrasonic or hot­wire welding. The fibrous sheath which surrounds tube 50 thus is not secured to the outer surface of the tube itself. This has practical advantages in permitting easier installation of the corrugated tube in trenches since the fibrous sheath will not be stretched or deformed due to the manner in which the tubes are coiled for purposes of storage.

The flexible corrugated tube structure is relatively simple to fabricate and requires minimal amount of time for installation in trenches adjoining highways for application as an edgedrain. The edgedrain results in an extremely effective product to transport water received as slow seepage as well as water received in high velocity pumping to a remote discharge point. The specific configuration of an outer structurally rigid shell of oblongate cross-section serves to permit the introduction of water into the hydraulic structure from two sides as well as providing a hydraulic structure which assists in the support of the edge of the sub-base and pavement. This assistance effectively slows the deterioration of the pavement and sub-base. The structure of the drain permits greater unobstructed fluid flow then is found in other currently known systems. The invention also has applications in other types of drainage, including agricultural and foundational, as well as along the paved or covered surfaces.