Note: Descriptions are shown in the official language in which they were submitted.
02/09/2001 18: 20 FAX 202982800 CA 02335417 2oo1-oz-12 ~ 004
'VOID-MA,INTAIN~NG GEOSYNTHETIC
LA1V~NATES AND DRAINAGE SYSTEMS
FIELD OF THE nWENTION
The present invention relates generally to void-maitntaining laminate
systems for the drainage of water and other fluids, and more particularly to
geosyathetic structures which can be assembled on-site such as laminates
having
high penmittivity and high transmissivity to fluids for utilization in the
subsurface
drainage ofroadways and other large structures such as parking lots, retaining
1.5 walls and buildings.
BACKGROUND OF TBE XNVENTI01~1
The building of large structures such as roadways, buildings, parking lots,
retaining walls, embanlaments and the like often involves the excavation, r~
contouring and other movement of large quantities of earthen materials such as
soil, rock, earth, gravel, sand and tlae like. Most large structures have
underlying
foundations of some sort to support the weight of the structure and thereby
stabilize the structure in its desired position with respect to~he earth and
with
respect to other paxts of the same structure. For example, roadways and
parking
lots usually have foundations comprising a base aggregate immediately under
the
paved surface, and a subgrade layer under the base aggregate which supports
the
weight of both of the overlying structures. Commonly, both the base and
subgrade are formed of stones, soil and other earthen nnaterials and subjected
repeatedly to grading, tampuag or other compaction operations ahd thereby
formed into a foundation of desired density, elevation, inclination and
direction.
Buildings commonly have concrete foundations or concrete slabs that support
the
weight of the overlying structure.
02/09/2001 18: 20 FAX 2029828300 CA 02335417 2001-02-12 f~ 005
LAMINA.TE~
The presence of water or other fluids near, within or under such
foundations can be quite disadvantageous. For_e~ample, uvater or other fluids
in
the foundation materials underlying such structures can cause hydraulic pore
pressure buildup and reduction in the effective stress in the soil materials.
These
conditions can directly or indirectly contribute to failure of the underlying
materials that support the overlying foundation and can thereby also cause a
failure of the overlying structure. It is thus important to positively control
the
water or other fluids and dissipate pore pressure underlying large structures
and in
the vicinity of and underlying the foundations of such large structures.
The movement of soil particles around and underlying structures is not
limited to that caused by the presence of fluids. Movement can occur from
repeated or repetitive dynamic loads, as well as static loads that cause
destabilizing stresses within the soil structure. One way of controlling such
movement is to provide reinforcing products such as frameworks which are
integral to tine materials underlying the foundation, or within it, to thereby
prevent
or impede such undesired movement. Geosynthetics are materials often used to
provide such a framework. The use of geosynthetics contributes to controlling
movement of soil particles and structural fill materials in four primary ways:
1) 13y creating higher degrees of friction between the natural materials and
the surface of the geosynthetic when compared to t~ frictional
characteristics of the soil itself in order to ~aainimize soil movement in
horizontal, vertical and diagonal directions.
2) By confining soil fill material within the geosynthetic stru~eture in an
attetinpt to control lateral movement of soil particles.
3) By providing a nonporous, impermeable membrane type >~arrier that
minimizes vertical migration of soil particles and fluids= At times,
horizontal and diagonal movement of soil particles is impeded by
roughening or texturing the geosynthetic in order to increase the friction
between the soil and the geosynthetic.
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. i ...
J
LA.MINA'T~S
4) By providing a senaiporous, porous, or permeable barrier that mininnizes
vertical migration of soil particles by not allowing soil particles to move
through openings in the geosynthetic th~tare effectively smaller than the
diameter of the soil particles themselves, while also allowing fluids to
migrate verticaky, diagonally and horizontally irrespective of gravity
through one or more layers of a single or mufti-ply geosynthetic.
These porous, semipoipomus or permeable geosynthetics allow fluids to
pass vertically and horizontally through their structures. Capillary
connections
x0 sometimes occur and are one aspect that allow fluids to migrate vertically
and
diagonally irrespective of gravity through mufti-ply geosynthetics. Capillary
connections are created by the contacting of two or more plys of geosynthetics
and pmvide continuous vertical or diagonal capiltary paths through which
fluids
may travel. Typically, capillary connections may appear in a semi-continuous
1~ pattern across the horizontal plane of a geosynthetic comprising more than
one
ply. These connections, which are formed when. the polymer strands of one ply
of
a geosynthetic contact the polymer strands of another ply often occur when
layers
of geosynthetics are arranged or constructed to show one ply to be placed
directly
on top of another ply. Polymer strands of individual geosynthetic plys assist
fluid
20 migration in the horizontal plane of the specific geosynthetic ply. This
horizontal
transmission of fluid can be expressed as a rate of flow per unit width within
the
plane of a geosynthetic and is typically called "traasmissiv'~3r." On the
other
hand, the vertical transm~i.ssion rate of fluid, or "permittivity" of a
geosynthetic is
typically expressed by measuring the rate of flow per unit area per unit
thielmess.
25 Permitivity is a guantifiable property that can be controlled during the
maufacturenng process.
Vertical and diagonal capillary connections can be created even when two
or more plys of geosynthetic are arranged in substantially but parallel planes
when
30 polymer strands of one ply become in contact with the polymer strands of
another
ply. This can occur under the normal pressures that are placed upon the
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,.,....,.
LAMINATES
/1,
geosyntheti,c from the overlying soil burden which forces polymeric strands of
the
separate plys together thereby allowing fluids to migrate against gravity at
the
sites of the continuous capillary connections. The llow of fluids through a
geosynthetic against gravity is often referred to as "wicking," and is
distinguished
from permitivity. Wicking occurs after field installation of the product and
is not
a predictably quantifiable characteristic of the system but is dependent on a
numvber of different factors. Wicking, the fluid transmission against gravity
resulting from capihary connections created by the deformation and
iutercontact
of geosynethic plys, is a properly that is sometimes advantageous and othex
times
disadvaatageous.For example, in applications where the user desires water to
be
transmitted against gravity these, capillary connections may provide a
benefit. In
contrast, using geosynthetics in applications where the user does not want
fluid to
pass via the mechanism provided by the capillary connection can. be a
detriment
to the particular structure.
In general, geosyuthetics are manufactured as substantially planar, or
sheetlike, products from polymeric materials. Geosynthetics are usuahy made in
large scale, for example, several meters in width and many meters in length so
that they are easily adaptable to large scale construction and landscaping
uses-
Some geosynthetics are flexixible or fabric-like and therefore conform easily
to
uneven or rolling surfaces. Some geosynthetics are manufactured to be less
flexible but to possess great tensile strength and resistance~o stretching or
great
resistance to compression. Certain types of geosynthetic materials are used to
reinforce large man-made structures, particularly those made of earthen
materials
such as gravel, sand and soil. In such uses, one purpose of using the
geosynthetic
is float of holding the earthen components together by providing a latticework
or
meshwork whose elements hour a high resistence to stretching. $y positioning
the geosynthetic integral to the gravel, sand and soil, that is, with the
gravel, sand
and soil within the interstices of the geosynthetic, unwanted movement o~ the
earthen components~is minimized or eliminated- Most geosynthetic materials,
whether of the latticework type or of the fabric type, allow water to pass
through
02/09/2001 18: 21 FAX 2029828300 ~ 02335417-2001-02-12 I~ 008
LAMINATES ~
them to some extent and into the material within which the geosynthetic is
integrally positioned. Thus, geosynthetic materials and related geoteehnical
engineering materials are used as integral parts.p~man-made structures or
systems
in order to stabilize their salient dimensions.
A particular problem faced by the FIiWAy the DOT and many highway
and transportation agencies across the United States and elsewhere is the high-
cost and difficult maintenance of state and interstate roadways. A
significant'
cause of this high cost and these difficulties is the entrapment and retention
of
water and other fluids which damage roadways and greatly reduce their useful
life. This is the case even on those projects where conventional geosynthetics
are
used. Water in pavement systems that are inclusive or exclusive of
geosynthetic
is one of the principal causes of pavement distress. Fluid such as water
enters the
subsurface either from the subgrade soil, that is, the native ground upon
which the
roadway is constructed, or from rainwater or floodwater penehabng open spaces
such as cracks and pits within the road surface. Under common usage, vehicular
traffic across the roadway produces a dynamic or repetitious loading force on
the
road that creates a 'dumping action'° that draws fluid through the
subgrade into
the subbase or base coarse of the road. VNhen this fluid is retained within
the
subbase or road base, damage to the roadway occurs. As indicated in the
AA.SHTO design methodology (1993), drainage performance can range ~rom
excellent (water is removed from the roadway systems witli~ two hours) to poor
drainage (water is removed within one month). The corresponding drainage
coe~cient (direct design parameter) for an excellent drainage is 3_0 times
greater
then the corresponding drainage coefficient for poor drainage. The higher
drainage coefficient increases the structural number. Therefore, the service
life of
the structures can be extended or the overall structural cross-section can be
reduced. When there is a high fluid content within the soil supporting the
traffic
lanes, reduced bearing capacity can occur, resulting in deformation of the
contour
of the road, wheel rutting, and premature collapse or failure of the roadway.
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i
LAN~INATES
Another drainage issue particular to construction of roadways and other
large structures in regions with cold climates relates to frost damage to
pavements
due to frost heaving and subsequent thawing. Frost heaving, the raising of the
pavement surface occurs due to the formation of ice lenses, which can grow up
to
several centimeters in the thickness, in the underlying soil. Differential
frost
heaving leads to adverse pavement roughness and hazardous driving conditions.
Thawing or frozen pavements in frost-melting periods causes a supersaturated
soil
condition. If the drainage provisions are inadequate, the bearing capacity of
the
pavement is substantially reduced, which in turn causes bearing capacity
failure or
surface~cracking. Traffc loading during the thaw season can also pump fine-
grained subgrade soils into the subbase or base course. Aunong the economic
losses by frost damage are costs of repair and maintenance, possible
restrictions
of vehicle weight-limits or even complete closure of the traffic. All of these
conditions can be extremely costly. To reduce damage caused by frost heaving,
in 1963 the ~J.S. Army Corps of Engineers suggested two strategies: 1)the
control
of surface deformation resulting from frost action by limiting the amount of
frost-
susceptible soil subjected to freezing temperatures; and 2) employing designs
of
adequately large bearing capacities sufficient to withstand stresses
experienced
during the most critical climatic period. This means a significant increase in
aggregate thickness and the concomitant increase in cost and time required to
construct a given structure.
Design methods based on the above two concepts call for the use of cleat,
non-frost-suscepa'ble base material. Such material is becoming more and more
expensive to obtain and transport. Due tv the required serviceability that an
engineer must account for in the design for their clients, these types of
expensive
soils are often forced to be considered in civil engineering projects, thus
making
demand for them higher and, consequently, an increase in their.prices_
Frost damage can be reduced by introducing a capillary break, or water
barrier, to reduce water migrarion into the freezing front. Various methods
are
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LAMINA,.TES
known to deal with this problem,. For example, Finland and Sweden have used a
layer or sand to break the capillary connection between frost susceptible
soils
(IZengmark, 1963; Taivenen, 1963). This insul~ti~r.~g layer o f sand was found
to
help reduce and smooth frost heave, and also to increase the bearing capacity
during the spring thaw.
Before the present invention, previous drainage systems using
geosynthetic structures are exclusively linuted to providing drainage at the
edge
or shoulder o~ a roadway. These edge-drain systems are commonly located
within a covered trench originally dug along the shoulder of the madrway, in
an
area which receives little or no dynamic load from the roadway. Usually
serving
a dual purpose, the edge-drain relies upon natural drainage from directly
beneath
the road surface within the subbase or subgrade to carry fluid to the edge-
drains
for collection and further distribution, for example, by way of a shoulder
pipe,
The material of the subbase or subgrade acts also as a filter to prevent
adjacent
soil from clogging the drainage system. The drainage systems directly beneath
the
surface of a madway is often made of unstabilized granular, asphalt sterilized
granular, or cement stabilized aggregate material. Such "natural matez~al"
drainage systems, if installed properly, can be used to carry large amounts of
fluid
$com the subbase to the edge-drain.
There are many disadvantages to natural material df~inage systems,
however. Such systems require the subsurface aggregate to possess a uniform
size gradation to provide void spaces, that is, interconnecting holes within
the
drainable base to carry fluid. Disadvantageously, the requirement for
interconnecting void spaces to afford good drainage conflicts with road
pavement
systems designed for long-term use. This is so because roadways_designed for
long-term use require minimal void spaces in order to reduce fibs movennent of
particles, sand and, aggregate. Free-draining aggregate usually require an
asphaltic or cement stabilize binder to facilitate construction. Additionally,
a
'well-graded granular or geotextile filter Layer is needed to prevent
contamination
7
02/09/2001 18: 21 FAg 2029828300 ~ 02335417-2001-02-12 I~ 011
LAMII~TATES ~
of the open graded base through the migration of subgtade fines. This extra
filter '
layer fiuther increases the cost of tlne roadway construction. Furthermore,
high
construction costs are incurred for a complete drainage layer of natural stone
or
sand that must be installed wrath precision, and extensive on-site qualify
control
must be exercised, in order to produce a higlrflow draining system which lasts
for
the life of the overlying paved surface.
When positioned directly beneath the road surface, conventional
geosynthetic structures are primarily used to pmvide reinforcement of the
base,
I O subgrade stabilization, subgrade restraint, separation of the base course
from the
subgrade, or as a thermal break to provide insulation from temperature
changes.
Until the present invention, however, geosynthetic materials had not been
designed or implemented tv provide a positive drainage system effective enough
to provide adequate drainage for an entire roadway or for an entire roadway
portion. Similarly, until the present invention, no geosynthetie material lead
ever
been designed to break the capillary connection that can occur as a result of
the
repeated dynamic tragic loads that can cause a capillary connection between
different plys of geosynthetics, nor has a geosynthetic ever been used to
provide a
void maintaining system for the entire design life of a roadway and thereby
serve
as an effective capillary break to prevent moisture migration into the base
course
layer or into the frost susceptible soil layer, or underneath an entire
roadway.
There is therefore a need for a drainage system that utilizes components
which can be engineered and manufactured offsite and can be then transported
to
a building site and positioned or arranged within a large structure and
pzovide
efficient and cost-effective drainage for the structure while also providing a
capillary break.
s
02/09/2001 _ 18 : 22 FAX 2029828500 CA 02335417 2001-02-12 C~] 012
J
LAMINATES'
SLfI~tARY OF THE INVENTION
The present invention overcomes the previously mentioned disadvantages
by providing a drainage system which includes a capillary break and drainage
voids under substantial portions of the ground underlying roadways, parking
lots,
retaining walls, buildings and other large structures. A geocomposite laminate
is
constructed and positioned within one or more of the subsurface levels at
predetermined locations under a large structure. Lanninates of the invention,
wlzieh typically comprise a void-maintaining structure such as a geonet
adjacent
to one or more flood-tzansmissable layers, preferably of geotextile or similar
fabrics, provide high transmissivity of subsurface fluids such as water into
the
core of the laminate and, through the interconnecting void spaces of the
laminate,
substantially horizontally away from the overlying structure thereby
eliminating
many of the problems presented by the presence or movement of fluids such as
water in the areas underlying large structures. By eliu~,ynating these
problems, the
useful life of the overlying structure is extended.
The permittivity of a material relates to its ability to permit gases, water
and other fluids to pass vertically, or substantially vemcally, through the
material.
The fluid-transmissible layers of the present invention provide high
permittivity
of subsurface fluids such as water into the core element. Ceotextxles aze
preferred
as the fluid-transmissible layers of the invention. Other m~erials possessing
high
petini.ttivity and high occlusiveness to solids are also suitable for the
present
invention. Structures of the present invention also possess high
tzansmissivity.
The tI'ariSm15s1vlty of a material zelates to its ability to transmit gases,
water or
other fluids~horizontally, or substantially horizontally, in a particular or
desired
direction. Typically, permittivity is measured as the rate of flow per unit
area per
unit width while transmissivity is measured in terms of rate of $ow per unit
width. Core elements of the present invention possess high transrnissivity
because of their interconnecting openings, which permit fluids to flow
substantially horizontally away from the overlying or underlying structure.
Thus,
02/09/2001 16:22 FA$ 2029628300_ CA 02335417 2001-02-12 X013
w -,
LAIV~rNA~'Eb
UVMG's eliminate many of the problems presented by the presence or movement
of fluids such as water in the areas underlying large structures. By
eliminating
these problems, the useful life of the subject str4tcture is extended.
The present invention relates generally to void-maintaining laminate
systems for water drainage, and more particularly to geosynthetic structures
such
as laminates for the subsurface drainage of roadways and other large
structures
such as parking lots, retaining walls and buildings.
A principal object of the invention is to provide subsurface geocomposite
laminate drainage systems that, among other things, provide a capillary break
to
thereby prevent unwanted movement of the structure, such as frost heaving, tv
thereby extend the useful life of a madway or other large structure.
It is another object of the prcsent invention to provide cost-effective
alternatives to previous large-structure subsurface drainage systems.
It is a further object of the present inveatYOn to transfer certain. quality
watrol aspects of road construction and reconstruction from the constructioa
site
to a manufacturing facility for roadway drainage products.
An additional object of the invention is to pmvide,composite mufti-ply
materials which include both void-maintaining elements anal geotextile or
other
filtration elements having high permitivity for fluids while also preventing
solid
particles thax are larger than openings in the filtration element from
entering the
void-maintaining system.
It is yet another object of the present invention to provide subsurface
drainage geocomposite laminates as part of a greater road subsurface
geosysthentic system to thereby enable efficient reinforcement, separation,
and
02/09/2001 16: 22 FAX 20 982,8300 CA 02335417 2001-02-12 f~ 014
LAM~TATE~ ~ ~ v ~ ;
drainage for a large structure such as a roadway, retaining wall, parking lot
or
but Iding.
..
In accordance with this and other objects, the present invention provides a
drainage system for draining fluids away from a roadway or other large
structure,
comprising a void-maintaining laminate, the laminate comprising a geocomposite
core layer having a plurality of interconnected voids, the core layer having
an
upper surface and a lower surface, and at least one fluid-traas~missible
layer,
preferably a geotextile layer, adjacent the upper surface, wherein the layers
arc
constructed sad arranged so that the laminate maintains voids of su~.cient
dimension that the water from the roadway or other large structure can move
freely through the Laminate, and wherein the laminate is sloped downwardly
from
the roadway or other large structure.
The void maintaining laminate may further comprise at least one tluid-
transmissible layer, such as a geotextile, adjacent the lower surface of the
laminate, and may also further comprise drain means adj scent the laminate and
communicating therewith such that the fluid can move from the surrotlndlng
soil
into the laminate aad then through the laminate to the drain means, wherein
the
ZO drain means is sloped preferably downwardly from the laminate. In
accordance
with advantageous drainage aspects of the invention the laminate is sloped
downwardky away from a portion of the roadway oi~ the lade structure such that
the fluid is directed away from the roadway or the large structure and the
laminate
communicates with the drain, means under the roadway or at a margin of the
madway or the large structure.
Xn accordance with additional objects of the invention, the drain means
may further comprise a ditch or culvert adjacent a margin of the-roadway or
the
large structure and the drainage means may comprise perforated piping such as
is
commonly found in oivil engineering applications.
m
02/09/2001 18:22 FAX 2029828300 CA 02335417 2001-02-12 f~015
L~vm~r~.~rES
Ia some preferred embodiments of the present invention, the laminate
wraps around the circumvference of the perforated piping and the perforated
piping
is connected to ftuther drains means wherein the further drain nneans is one
or
more selected from the group consisting of non-perforated pipes, drainage
ditches,
sumps, canals, streams and rivers. Preferably one or both of the fluid-
transmissible layers, preferable of geotextile, are attached to the
geocomposite
core layer by heat or fusion welding, by laser welding, or by adhesives known
in
the geotextile arts. Of course, as one of skill in the art can appreciate, is
certain
applications, it may be most efficacious to position the geotextile layers
adjacent
the geocomposite core layer without attaching them to one another. 'This may
be
preferable in situations where separate portions of geocomposite core layer
are
overlapped or butt joined to one another and where it is desirable that no
similar
joint exists in the corresponding geotextile layer.
In other preferred embodiments of the invention, the high permittivity
core element comprises a geonet such as that found in U.S. Patent 5,891,549 to
Beretta et al. In other preferred embodiments, the geocomposite core element
is
tri-planar such as shown in U.S. Patent 5,255,998 and comprises polyethlene,
polypropylene or other polymer derivatives, and both fluid-transmissible
layers
are geotextiles that are nonwoven and needle punched. U.S. Patents 5,891,549
and 5,255,99$ are incorporated herein by reference.
rn accordance with additional advantageous aspects of the invention, the
void maintaining laminate is constructed and arranged to form a wrapping
adjacent to and around the circumference of the perforated piping such that a
portion of oiie of the upper or lower fluid-transmissible layers, preferably
of
geotextile, is removed along the length of the wrapping so that the
geocomposite
core contacts the piping and the removed portion of the one of ~e upper or
lower
fluid-transmissible geote~ctile layers is overlapping and cozunected to the
other
surface fluid-transrriissible geotextile layer. As one of s1d11 in the art
will
recognize, it is advantageous to provide piping or other drain means which has
a
12
0 /09/2001 16:22 FAX 2029628300, CA 02335417 2001-02-12 f~016
~l
LAMINA'TE~ '
capacity tv carry away a sufficient volume of fluid collected through the
relatively
large surface area of the present geocomposite core layer.
.:
_.
Moreover, by interconnecting the various portions of the present invention
such that the various interconnecting voids maintain flow paths for fluid such
as
water entering the system, large areas under highways, buildings, parking
lots,
and other large structures can be effectively drained without the necessity of
complex and expensive structures. In order to maintain the interconnections
preferred in the present invention, the overlapping portions of the fluid-
transmissible geotextile layers are connected by ties, welding yr by sewing,
and
the portions of the fluid-transmissible geotextile layers and the geocomposite
core
of the laminate are held adjacent to the piping by eircumferential ties around
the
laminate. Of course, as one of skill will recognize, the present invention is
particularly advantageous for draining water-containing fluids or other
geologic
fluids such as petroleum or natural gas from roadways and other large
structures.
In accordance with still other aspects of the present invention, a drainage
system disposed at a level below the top surface of a roadway for draining
fluids
such as water away horn. the roadway is provided, wherein the system comprises
a wid-maintaining laminate comprising a geocomposite core layer having a
plurality of interconnected voids, the core layer having an upper surface and
a
lower surface, and at least one fluid-transmissible layer of~,igh
transmissivity,
preferably of geotextile, adjacent the upper surface, wherein the layers are
constructed and arranged so that the laminate maintains voids of sui~tcient
dimension that the water from the madway can move freely through the lamynate,
and wherein the laminate is sloped downwardly from the top surface of the
roadway.
rtr accordance with fi~rther advantages of the present invention, the present
void maintaining laminate fuzther comprises iii) at least one fluid-
transmissible
layer, preferably a geotextile, adjacent the lower surface of the laminate
and,
13
02/09/20oi i6;22 FAX 2029628900 CA 02335417 2001-02-12 1017
.v
L.AMINATES~
preferably, drain means adj scent the laminate and communicating therewith
such
that the fluid can move from the soil through the fluid-transmissible layer or
layers and into the laminate core to the drain means, wherein the drain means
is
sloped downwardly from the laminate such that the fluid is directed away from
the roadway, wherein the laminate is constructed and arranged to provide a
capillary break between the roadway top surface and the earthen materials
under
the laminate.
In accordance with other aspects of the present invention, the vvid-
maintaining laminates of the present invention caa be positioned in. a roadway
to
maximize their effectiveness. For example, the laminate can be positioned
intermittently or continuously below the top road surface of a midway to
reside
below the top road surface and above a side grade, below the top mad surface
and
below a subgrade, for example, at Ieast two feet below a subgrade, to reside
above
an aggregate structure. In order to maximize other advantages of the present
invention, the void maintaining laminates znay be positioned in multiple
layers, or
above the ground water table, and at various levels below the roadway surface
in
order to maximize drainage efficiency as desired.
The void-maintaining laminates and fluid-transmissible layers of the
present invention can be made in large pieces for example, in pieces several
meters wide and many meters long. For convenience and installation, however,
the laminates of the present invention, or their components can be installed
in
portions which are interconnected such that the interconnecting voids are of
ZS suf~~eient dimension that the water from the roadway can move freely
through the
laminate and can be connected to drain means such as a ditch or culvert
adjacent a
margin of the midway or the large structure or perforated piping.
Moreover, the void-maintaining geowmposites of the present invention
can be constructed and arranged to prevent wicking upward, to provide
14
02/09/2001 16:22 FAX 2029828300 CA 02335417 2001-02-12 1018
T.-
_._.,l
LAMxIVATE~
continuous or discontinuous capillary breaks across the area of the
geoeomposite,
or to prevent wicking substantially altogether by the provision of void
spaces.
Other advantages of the present invention are found in the methods which
it provides. The present invention includes methods for providing drainage
systems for roadways or other large structures. For example, the present
invention provides a method for constructing a drainage system for draining
fluids
away from a roadway or other large structure, the method compzising providing
a
void-maintaining laminate comprising a geocomposite core layer having a
plurality of interconnected voids, the core layer having an upper surface and
a
lower surface, and at least one fluid-transmissible layer, preferably of
geotextile,
adjacent the upper surface, wherein the layers are constructed and arranged so
that
the laminate maintains voids of sufficient dimension that the water from the
roadway or other large structure can move freely through the laminate, and
wherein the laminate is sloped downwardly from the roadway or other large
structure.
Preferably, the void-maintaining laminate further comprises at least one
fluid-transmissible layer, preferably a geotextile of high permittivity
adjacent the
lower surface of the lau~inate and drain means adjacent the laminate and
communicating therewith such that the fluid can move from the surrownding soil
or aggregate through the fluid-transmissible layer into the~nate core and
thereby to the drain means, wherein the drain mesas is sloped downwardly fzom
the laminate.
The'fluid-transmisssible and core layers of the laminates of the invention
can be positioned at junctions between pieces such that high permittivity of
the
fluid-transmissible layers and the high transmissivity between the void spaces
foamed by thewarious layers and those of the drain means is maintained. With
respect to the joining of large pieces of the laminates, this can be
accomplished by
providing, for example, geotextile or other fluid-transmissible layers which
02/09/2001 18:23 FAg 2029628300 CA 02335417 2001-02-12 0019
"t, - 1 -.
LAMINATES '' "~
extend beyond the margins of the core composite layer, or by positioning
additional pieces of geotextile over the joint areas. With respect to the
junctions
between the drain means and the laminates, porkians of the fluid-transmissible
layers can be positioned around the drain means to thereby decrease the
likelihood
of the intrusion of clogging materials and to maintain the connection between
voides of the laminates and those of the drain means.
The means aid methods of the present invention include the positioning of
the laminates and drain means in many permutations depeading on the particular
needs of the structure to be drained. 1~or exannple, laminates of the
invention can
be positioned below the roadway or large structure, above an aggregate layer,
or
above the ground water table, if desired. Moreover, the present methods
include
combinations wherein the laminate is positioned below the roadway or large
structure in. portions which are interconnected such that the interconnecting
voids
I S are of sufficient dimer~.sion that the water ~mm the roadway caa move
freely
through the connecting portions and thereby through the laminate. The present
methods include wherein the drain means further comprises a ditch or culvert
adjacent a margin of the roadway or the large structure.
,A.s a further advantage, the combinations and methods of the invention
include wherein the roadway base course comprises materials which have been
excavated from the subgrade of the roadway and wherein ifte roadway base
course
comprises materials which have been excavated from the subgrade of the roadway
_.
and mixed with imported materials.
BRIEF bESCRIPTION OF' T~ DRAWINGS
t6
02/09/2001 16: 23 FAX 2029628900 CA 02335417 2001-02-12 I~ 020
..
~.AMnnA't L~
Fig. I is a cross-sectional view of a preferred embodiment of the laminates
of the present invention in operative combination with a roadway forming a
capillary break adjacent frost susceptible soil. _, . ~'
Fig. Z is a cmss-sectional view of an alternative embodiment of the
present invention in operative combination with a roadway to provide roadway
base or subbase drainage, wherein the drainage system is positioned between
the
roadway subgrade and portions of the roadway base aggregate.
Fig. 3 is a cross-sectional view ofanother alternative embodiment of the
present invention in which two geocomposite-larrninate drain combinations are
shown in operative combination with a roadway having a surface of asphalt or
concrete pavement.
1 S Fig. 4 is a cross-sectional view of a drainage system according to the
invention, and shows details of connecting portions of a laminated.
geocomposite
to a collection pipe installation where the system lies below or over a
subgrade.
Fig. 5 is a cross-sectional view of a drainage system according to the
invention showing details of portions of the present laminates connecting tv a
collection pipe installation where the system lies at the bottom of an
aggregate
layer.
Fig. 6a is a cross-sectional view of adjacent geocomposite laminate rolls .
showing joint and tie intersections.
Fig. 6b depicts a detailed cross-sectional view of a butt joint.
Fig. 6c is a detailed cross-sectional view of an overlap joint.
m
-.02/09/2001 16:29 FAX 202962800 CA 02335417 2001-02-12 1021
LAMI1~TA1 ~.~
Fug. 7 is a cross-sectional view of void-maintaining geocotnposite
laminates combined with geotextile layers as part of a greater mad subsurface
geosynthetic drainage system.
DETAILED DTSCRIPTION OF TH.C INVE1~TION
With reference to FIG.1, one preferred embodiment of the drainage
x 0 system I O according to the present invention is depicted. In common
usage,
vehicular traffic 22 occurs across roadway 20. The roadway structure generally
includes asphalt layer 24, base 28, and subgrade 36. Commonly, the base is
comprised of aggregate, and the aggregate may comprise a variety of materials
including crushed stone, rock, gravel, lime, millings and other materials. As
one
of skill in the highway and civil engineering arts wih appreciate, although
the
above-described madway is a common roadway structure, there are many other
examples typical of roadway structures. Roadways commonly may include other
combinations oFthe asphalt or concrete surface layer, base, subbase, and/or
aggregate additives such as crumbs, granules, crushed concrete and masonry,
and
fly ash as are available or needed for a particular roadway structure
application.
In the preferred embodiment shown in Fng. l, the laminate drainage system 10
lies below subgrade 36_ Subsurface drainage occurs as fl>~ds, such as water or
trapped gases fiom the natural ground are directed dowawardly through subgrade
36 to void-m~~aintaining geocomposite 1Z to drainage collection pipe 38, which
is
preferably porous or perforated, and located beneath read shoulders 26 on
either
side of roadway 20. Subsurface drainage occurs also as fluids, such as water
from
the natural ground water are directed upwardly through subgrade 36 through
upward capillary action into laminated void-maintaining geocomposite I2 to
drainage collection pipe 38, which is preferably porous or perforated, and
located
beneath mad shoulders z6 on either side of roadway 20.
18
02/09/2001 18: 23 FAg 2029828300 CA 02335417 2001-02-12 C~] 022
..
LAM1IVA'l ~,~
FIGS. Z and 4(b) together show an alternative preferred embodiment of
the present invention. In FIG 2 a detailed cross-section of a portion of
drainage
system 10 is shown. Drainage system 10 gener~ly comprises a laminated void-
maintaining geocomposite x2. Void-maintaining geocomposite 12 preferably
includes a care ld with a rigid upper and lower surface. Attached adjacent the
upper surface of void-maintaining geocomposite 12 is upper surface fluid-
transmissible geotextile 16 and firmly attached adjacent the lower surface of
void-
maintaining geocomposite 12 is lower surface geotextile x8_ Advantageously,
void-maintaining geocomposite 12 comprises a core element structured such
that,
under great compressive Load, interconnecting voids are maintained therein. In
the Preferred embodiment shown, void-maintaining geocomposite 1Z comprises a
thick tri-planar polyethlene structure anal geotextiles 16 and 18 comprise
nonwoven needle punched, spun-bouad or woven polymer-based textile or fabric-
based structures adjacent to the respective upper and, lower surfaces of
geonet
core I4. Geonet core element structures are generally lrnown in. geocomposite
arts and therefore are not described in great detail herein. Commonly, a
geonet
comprises a thermoplastic polymer extrusion processed into a net style.
Geonets
can be adapted to use with the present invention by being further formed into
structures which maintain void spaces under high compressive loads to thereby
ensure a high transmissivity to fluids which in turn permits rapid drainage
flow.
Although a geonet core is preferred, other polymer-based geosynthetic core
elements providing high transmissivity are also suitable to$e used to form
laminated geocomposites for subsurface drainage system 10_ . _
)~G. 3 depict alternative preferred embodiments of the present invention.
Tn >fXG. 3, drainage system 10 lies directly underneath a PCC or asphalt Iayer
24.
High-flow drainage is provided by drainage system 10 as it directs fluid such
as
rainwater either from the road surface to drain collection pipes~36. Also,
drainage
systems I O may be positioned individually or in a plurality of sets in other
sections of the subsurface structure depending upon design choice and specific
drainage requirements_ For example, buildings or parking lots in areas where
19
02/09/2001 18:29 FAX 2029828300 ~ 02335417 2001-02-12
~ 023
. " '; . .
LAM~NA1 ~:~
upflow of water and other fluids is common may require a plurality of systems
10
at various levels and dispositions.
J
>fIGs. 5a and ~b depict cross-sectional views of embodiments of drainage
systems according to the invention and show details of connecting portions of
the
geocomposite to a collection pipe installation where the system lies below or
over
a subgrade, and where a system lies underneath an aggregate bed. Fig. 5b shows
a detailed view o~the attachment of void-maintaining geocomposite 1Z to
drainage collection pipe 38 for subsurface drainage system 10. FIG. 5(a) is
directed to a preferred embodiment where drainage system 10 lies along the
bottom o~aggregate bed 32 while FIG. 5(b) shows graphically the relative
placement of the geonet core 14 and fluid-transmissible layers 16 and 1S.
Advantageously, void-maintaining geocomposite 12 is wrapped around perforated
pipe 38, wherein a portion of upper surface geotexbile 18 xs removed from the
core element such as to ensure the free flow o~ fluid from void-maintaining
geocomposite 12 to pipe 38. Preferably, the removed portion of geotextile 18
is
overlapped with a portion of lower surface geotextile 14 to thereby prevent
entry
of clogging materials to the void spaces of system 10. The overlapping
portions
of geotextiles 18 and 16 are preferably connected to one another by welding,
ZO sewing, ties, adhesives or other means. Also, portions of the overlapping
geonet
core x4 are preferably secured adjacent perforated piping 38 by
circumferential
ties of plastic or polymeric braid (not shown).
rn;stallation of draitnage system 10 under a roadway, parking lot, building
or retaining wall can be understood with reference to FIGS. l-7. With
reference
to FIGs.1-3, soil is removed below subgrade elevation to a depth appropriate
to
the particular project on a site-specific basis. Void-maintaining geocomposate
laminate 12, preferably from 8 -12 mm thicl~ is placed across the entire
roadway
to create a capillary break. As depicted in FIGs.1 and 3, void-maintaining
geocomposite laminate 12 is installed from mlls transported to the site and
unrolled to cover the selected layer of the subsurface. In many cmbodiments,
it is
ao
02/09/2001 1g;23 FAg 2029828300 ~ 02335417 2001-02-12 f~j024
LAMINAZ ~.:~
preferable to install the geocomposite lamin~a~tes such that the flow of fluid
is
directed in directions substantially perpendicular tv the longitudinal axis of
the
roadway. Additionally, in some embodiments, ~eid-maintaining geocomposite x2
may include edges conning parallel to the longitudinal axis of the roadway
wherein the edges serve as edge-drains connecting to drainage collection
pipes.
As shown in IfIGs. 6a-6c, joints between roll sections can be overlapped
to form overlap joints 102 or tied together to form butt joints 104.
Preferably,
overlapping occurs at least 3 inches along the void-maintaining geocomposites
roll length and at least 3 inches along the void-maintaining geocomposite roll
width while ties occur every one foot along the roll length and overlapping
occurs
in the direction that the excavation fill will be spread so that forces placed
upon
the void-maintaining geocomposite laminates during installation do not result
in
unwanted shifting. Adjacent void-maintaining geocomposite rolls are preferably
joined by tying together the geonet cores with plastic fasteners or polymeric
braid
spaced every 3 feet or so along the roll length and every one foot across the
roll
width or by an alternative design selection. Additional pieces of fluid-
transmissible layer, such as geotexfile, may be placed over the joint areas
where
two pieces of void-maintaining laminate are joined.
Installation procedures are similar for other preferred embodiments of the
present invention and are shown in, for example, FIGS. 2-'~. As shown in k'IG.
2,
void-maintaining geocomposite laminate ><2 rests over a subgrade. Preferably,
the
geocomposite lies at the bottom of the base of road subsurface structure and
extends upward to wrap the base aggregate. In r'IG. 4, void-maintaining
geocomposite 12 lies directly underneath the PCC or asphalt layer to drain the
pavement surface_
As shown in lfIGs. 1 and 2, drainage collection pipe 38 is attached to
void-maintaining geocomposites 12, and in some preferred embodiments, can be
installed on preferably both sides of the roadway under road shoulder 26, for
the
2x
02/09/2001 18:28 FAX 2029828800 ~ 02335417 2001-02-12
LAMINA.' ~;o
~ 025
entire length of drainage system 10 as it extends along the path of the
roadway.
The drainage pipe is freely fluid-transmissible, that is, porous, or
preferably
perforated, allowing high-flow drainage from void-maintaining geocomposites lZ
to collection pipes 38, which are located at a depth below the level of void-
maintai~ning geocomposites 12. Advantageously, outlets or valves for pipes 38
or
geocornposites 12 may be provided for testing applications ofdrainage systems
10,
FIGs. 6(b) and 6(e) provide a cross-sectional view of adjacent void-
maintaining geocomposite rolls 60 and their various manners of attachment for
multiple preferred embodiments. Adjacent rolls comprising the upper
geocomposite layer 62 lying over the top of aggregate 32 are tied together
with
plastic fasteners or polymeric braid. The tying of adjacent geonet cores is
similarly done for the other gecomposite layers lying along the base of
aggregate
32, and lying over and below the subgrade 36: Preferably for the upper
geocomposite layer 6Z, joints 104 are formed between two connecting
geocomposite core rolls by tying at the edge of the rolls using plastic
fasteners yr
polymeric braid_ FIG. 66 provides a cross-sectional view of butt joint x04
formed with the help of ties 68 for connecting two upper geocomposite rolls
60.
Alternatively, for connecting corresponding layers within the present
systems, an overlap joint such as joint 72 is used to conne~successive
geocomposite rolls, F1G. 6c shows a detailed cross-sectional view of the
overlapping performed for connecting geocomposite rolls 100 lying at the base
of
aggregate 32, and lying over and below subgrade 36. If necessary or desired
for a
particular application, portions of the high permittivity fluid-transmissible
layer or
layers may be removed from the core element in order to allow the maximum
amount of effective interconnection between the core element and the drain
pipes.
Preferably, the overlapped portions of the geocorr~posite mils are secured by
heat
bonding, adhesive, sewing, or some alternative design selection.
22
02/09/2001 16:24 FAX 2029628300 ~ 02335417 2001-02-12
.'
LAM~VAT ~,; ' ,
~J 026
FIG. '1 shows drainage system 10 as part of a greater madway subsurface
system, geosynthetic system. Tn combination with the drainage section l I O
n~nmng concurrently yr successively with the oxher sections, a roadway
subsurface system is created for efficient roadway perfornlance and longer
service
life. FIG. 7 shows drainage system 10 having upper and lower geotextile layers
90 joined to geonet core I14. Advantageously, major components of the present
drainage systems can be designed and prepared at an o~ site manufacturing
facility to thereby decrease the probability of component erroxs inherent in
on-site
desig~a and placement.
As one of skill in the art will appreciate, the present methods of the
inventions can include one or more of the elements described above in numerous
permutations to arrive at high transmvissivity drainage systems for roadways
and
' other structures that are within the spirit and scope of the present
invention.
-_
23
