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Geocomposite sheet drain joining
Geotextiles and Geomembranes 9 (1990) 501-506
Geocomposite Sheet Drain Joining
B a o - L i n H w u & R o b e r t M. K o e r n e r Geosynthetic Research Institute, Drexel University, Philadelphia, Pennsylvania 19104, USA
ABSTRACT This short paper is focused on the joining of the edges and~or ends of geocomposite sheet drain panels or rolls to one another, or to their outlet structures. Experimental data are given for the amount of overlap needed for tensile strength mobilization and details are provided on various outlet connections.
INTRODUCTION Geocomposite sheet drains come in large panels or in long rolls and are used for their in-plane flow capability to transport liquids of various types and quantities. They have a wide variety of shapes, configurations and properties as seen in the listing provided in Table 1. Note that the strength referred to in Table 1 is the compressive strength normal to the core and not the tensile strength which will be considered later in this paper. The applications for these materials are varied, but three uses are very c o m m o n ; for drainage behind rigid retaining walls, for plaza deck drainage and as surface water drains in landfill caps. The geosynthetic literature is abundant with these and other applications. Whenever a panel or a roll terminates, its flow continuity at the ends and sides must be assured. Since many geocomposite sheet drains are dimpled, cuspated or indented, there is a natural male-to-female overlap coupling capability which can be utilized. Details of how many repeat rows are necessary to mobilize tensile strength, however, are scarce. This aspect will be investigated experimentally. Also very important are the outlet details which will be reviewed via a manufacturer's literature search. 501 Geotextiles and Geomembranes 0266-1144/90/$03.50(~) 1990 Elsevier Science Publishers Ltd, England. Printed in Great Britain
Company
Greenstreak
Mirafi
Monsanto
Nilex
6
7
8
9
PDS 40
PDS20
NudrainC
WD 300
Miradrain 9(1(10 WD 100
SheetDrain Deck Drain Miradrain2000 Miradrain 4000 MiradrainS000 Miradrain6000 Miradrain6200 Miradrain 8000
Tigerdrain
Hitek 40c
Hitek 20c
3Dweb 3D web 3Dweb 3Dweb n/a
Shape
Dimpled Dimpled Dimpled Double cuspation Polyethylene Double cuspation Polyethylene Double cuspation Polyethylene Open cuspation Polystyrene Raisedcore Polystyrene Raised core Polystyrene Dimpled Polystyrene Dimpled Polystyrene Dimpled Polystyrene Dimpled Polystyrene Dimpled Polyvinyl Dimpled chloride Polystyrene Dimpled Polyethylene Hollow columns Polyethylene Hollow columns Polyethylene Double cuspation Polyethylene Double cutipation Polyethylene Double cuspation
Polyethylene Polystyrene Polystyrene Polyethylene
Nylon 6 Nylon 6 Nylon 6 Nylon 6 n/a
Material
1.50
0.75
0.79
0.45
(I.38 0-36
(I-38 0-38 0-38 (I-75 11-38 0-38 0-38 0.38
0.60
1-58
11-79
0-44 0.44 0.44 0.26
0-40 0-80 0.40 0.80 n/a
Thickness (in)
n/a
n/a
5000
30 000
18000 15 000
10500 19000 10 800 4 300 15 000 15 000 15 1]00 18 000
5 500
2 500
5 000
12 500 15 000 18 0 ~ 9 900
----n/a
Strength u (Ib/[t21
Polypropylene nonwoven
Polypropylene nonwoven
Polypropylene nonwoven
Polypropylene nonwoven
Polypropylene woven Polypropylene nonwoven
Polypropylenenonwoven Polypropylene woven Polypropylenenonwoven Polypropylene nonwoven Polypropylenenonwoven Polypropylenenonwoven Polypropylenenonwoven Polypropylene woven
Polypropylenenonwoven
Polypropylene nonwoven
Polypropylene nonwoven
Polypropylene nonwoven Polypropylene nonwoven Polypropylenewoven Polypropylene nonwoven
Polyester nonwoven Polyester nonwoven Polyester nonwoven Polyester nonwoven n/a
Geotextile polymer ~nd type
22
9.6
24
3(1
15 20
14 21.5 15 5 15 15 15 15
9
22
9-6
18 26
18
18
n/a n/a 10 21 n/a
1.45 psi
@
22
9-6
n/a
30
15 20
12.6 20 15 n/a n/a 15 15 15
8
n/a
9.6
16 16 16 2-1
n/a nda 2 6 n/a
14.5 psi
@
Flow rate" (gpm/fi)
"Note that these v a l u e s of c o m p r e s s i v e s t r e n g t h are f r o m m a n u f a c t u r e r s ' literature and h a v e b e e n d e r i v e d by d i f f e r e n t test m e t h o d s a n d / o r procedures.
10 Pro Drain Systems
Exxon
5
4
Enkamat 7010 Enkamat 7020 Enkadrain 9010 Enkadrain 9120 Aquadrain 15X
Trademark
Amerdrain480 Amerdrain 500 Amerdrain650 Burcan Industries Hitek 6c
American Colloid Co. 3 American Wick Drain Co.
2
1 Akzo
No.
Core characteristics
TABLE 1 Properties of Commercially Available Geocomposite Sheet Drains as Listed in Manufacturers' Literature L]l
~0
F
t~
bo
503
Geocomposite sheet drain joining
O V E R L A P J O I N I N G OF G E O C O M P O S I T E D R A I N A G E C O R E S For most of the sheet drain cores listed in Table 1, for example, products n u m b e r e d 2, 3, 4, 5, 6, 7, 9 and 10, the joining of panels can be accomplished by a male-to-female overlap connection of the repeat rows of their core structures. Just how many rows are necessary to mobilize the tensile strength of the core is the subject of this experimental study. Tensile tests were performed on 8-0 in (200 mm) wide width sections of the cores and then compared to overlapped joints of the same width incorporating from 1 to 7 rows of the protrusions of the overlapped section. No bonding or gluing of the overlap was performed, although the sheets were resisted from riding up over one another by a low normal stress of 4 kPa (0.5 lb/in2). This was felt to model properly a minimum type of compressive stress in the field. The results are shown in Fig. 1. Here it is seen that the core tensile strength is mobilized quite slowly as the n u m b e r of incorporated rows is increased. For two of the products the protrusions
100
80
J~ O
60
:E J¢:
g
¢D
_¢ 40 p¢1 o
Product "G" •
,I,
]product iT,
20 ConfiningPressure: 4 kPa 1
Numberof Rows Incorporated in the OverlappedJoint Fig. 1. Mobilizationof core tensile strength by overlapped geocomposite sheet drains as a function of number of rows incorporated.
504
Bao-Lin Hwu, Robert M. Koerner 120
_1
100
80
•
Product "M', 3 Rows
•
Product "G', 3 Rows
•
Product "T', 2 Rows
60
"g
g
I
I
40
kS
20
0
0
10
20
30
40
50
60
70
Confining Pressure (kPa)
Fig. 2. Mobilization of core tensile strength by overlapped geocomposite sheet drains under different confining pressures.
laterally d e f o r m e d and the mobilized strength was quite low. However, it must be m e n t i o n e d that most sheet drain systems are generally not u n d e r tension and only must carry enough tensile stress to provide continuity of flow. This is the case for retaining wall and plaza deck drainage, but might not be the case for landfill cap drainage. These same sheet drain cores were further evaluated as to the effect of increasing confining pressure with results given in Fig. 2. H e r e it is seen that greater normal stress rapidly increases the tensile strength of the coupled zone. The 2 or 3 rows of overlapped area often referred to in manufacturers' literature appear to be adequate as the normal pressure is increased. It should be noted, however, that some of the cores listed in Table 1 cannot be joined in the interlocking m a n n e r just described. For these products a friction overlap is required or some type of mechanical coupling of butt-jointed ends. While this decision is product specific, it must be cautioned that liquid flow in the core itself cannot be restricted.
Geocomposite sheet drain joining
505
Wall Retaining Wall
[":B]ti)l~'*" i i ~ i t / FIIter
.t_ /Filter
Fabric
~:7~1~ ..Geocompoilt.
Water-
~..'-.*.ll~ _ .~I,!~i
Proo.ng :~iE ::::&i --
Fabric
Geocompo.lte I S h e e t Dr.ln
Sheet Drain
,:.:.
Native Soil
Native Soil
weep
i:7:]Fl Parlor.ted 7:':.'11;[ Discharge :'*.*:J[;i Pipe
Hole
(b) Retaining Wall
(it) Foundation Wall
Retaining et
:::*:
.Filter Fabric
•.'." ~'. . :.*:
.Geocompo.lta
::::: ,'-**
:!:i::
~
......
',::::'7~" "
VegetalJ on. . . . . . . Soll
praln
Sheet Drain
l
Native Soil Perforated
/Oiich.rg.
i!ii! ,/Pip. (c) Retaining Wall
Pipe
:iiiiiit :.:.*.~
/ /
/G.ocolmpoilte
Sheet Drain
Anti-Root Layer
i!:.'ili'*'*'*t Waterproofing
(d) Plaza (Deck)
Drain
Fig. 3. Various outlet details for geocomposite sheet drains (from various manufacturers).
O U T L E T D E T A I L S OF G E O C O M P O S I T E S H E E T D R A I N S For most applications of geocomposite sheet drains, the core conveys liquid to a drainage outlet which is often a perforated pipe. This connection is a critical detail and must be done in a careful and workmanlike manner. Since the variations are somewhat product specific we have collected a set of manufacturers' suggestions and presented them in Fig. 3. They have been found to be successful via past practice and are recommended for continued use. Note that the geotextile wrapping of the completed core-to-pipe connection is an extremely important detail. Without complete geotextile coverage of both the drainage core and the perforated pipe, soil intrusion can block the entire flow system at its most critical location, i.e. at its exit.
506
Bao-Lin Hwu, Robert M. Koerner
SUMMARY This brief paper has focused on geocomposite sheet drain joining and connections. Since most of the drainage core products are vacuum formed in their fabrication they have a natural male-to-female joining capability. It was shown experimentally that 2 or 3 rows of repeat units are generally sufficient to mobilize the core's tensile strength. Other core types must be evaluated on a product-specific basis. The outlet connection for the liquid conveyed in the core, which is usually via a perforated pipe, was also addressed. Various manufacturers' schemes were presented where it was seen that workmanship and complete geotextile encapsulation of the drainage components are critical aspects of the various types of connection.
Geocomposite Sheet Drain Joining
B a o - L i n H w u & R o b e r t M. K o e r n e r Geosynthetic Research Institute, Drexel University, Philadelphia, Pennsylvania 19104, USA
ABSTRACT This short paper is focused on the joining of the edges and~or ends of geocomposite sheet drain panels or rolls to one another, or to their outlet structures. Experimental data are given for the amount of overlap needed for tensile strength mobilization and details are provided on various outlet connections.
INTRODUCTION Geocomposite sheet drains come in large panels or in long rolls and are used for their in-plane flow capability to transport liquids of various types and quantities. They have a wide variety of shapes, configurations and properties as seen in the listing provided in Table 1. Note that the strength referred to in Table 1 is the compressive strength normal to the core and not the tensile strength which will be considered later in this paper. The applications for these materials are varied, but three uses are very c o m m o n ; for drainage behind rigid retaining walls, for plaza deck drainage and as surface water drains in landfill caps. The geosynthetic literature is abundant with these and other applications. Whenever a panel or a roll terminates, its flow continuity at the ends and sides must be assured. Since many geocomposite sheet drains are dimpled, cuspated or indented, there is a natural male-to-female overlap coupling capability which can be utilized. Details of how many repeat rows are necessary to mobilize tensile strength, however, are scarce. This aspect will be investigated experimentally. Also very important are the outlet details which will be reviewed via a manufacturer's literature search. 501 Geotextiles and Geomembranes 0266-1144/90/$03.50(~) 1990 Elsevier Science Publishers Ltd, England. Printed in Great Britain
Company
Greenstreak
Mirafi
Monsanto
Nilex
6
7
8
9
PDS 40
PDS20
NudrainC
WD 300
Miradrain 9(1(10 WD 100
SheetDrain Deck Drain Miradrain2000 Miradrain 4000 MiradrainS000 Miradrain6000 Miradrain6200 Miradrain 8000
Tigerdrain
Hitek 40c
Hitek 20c
3Dweb 3D web 3Dweb 3Dweb n/a
Shape
Dimpled Dimpled Dimpled Double cuspation Polyethylene Double cuspation Polyethylene Double cuspation Polyethylene Open cuspation Polystyrene Raisedcore Polystyrene Raised core Polystyrene Dimpled Polystyrene Dimpled Polystyrene Dimpled Polystyrene Dimpled Polystyrene Dimpled Polyvinyl Dimpled chloride Polystyrene Dimpled Polyethylene Hollow columns Polyethylene Hollow columns Polyethylene Double cuspation Polyethylene Double cutipation Polyethylene Double cuspation
Polyethylene Polystyrene Polystyrene Polyethylene
Nylon 6 Nylon 6 Nylon 6 Nylon 6 n/a
Material
1.50
0.75
0.79
0.45
(I.38 0-36
(I-38 0-38 0-38 (I-75 11-38 0-38 0-38 0.38
0.60
1-58
11-79
0-44 0.44 0.44 0.26
0-40 0-80 0.40 0.80 n/a
Thickness (in)
n/a
n/a
5000
30 000
18000 15 000
10500 19000 10 800 4 300 15 000 15 000 15 1]00 18 000
5 500
2 500
5 000
12 500 15 000 18 0 ~ 9 900
----n/a
Strength u (Ib/[t21
Polypropylene nonwoven
Polypropylene nonwoven
Polypropylene nonwoven
Polypropylene nonwoven
Polypropylene woven Polypropylene nonwoven
Polypropylenenonwoven Polypropylene woven Polypropylenenonwoven Polypropylene nonwoven Polypropylenenonwoven Polypropylenenonwoven Polypropylenenonwoven Polypropylene woven
Polypropylenenonwoven
Polypropylene nonwoven
Polypropylene nonwoven
Polypropylene nonwoven Polypropylene nonwoven Polypropylenewoven Polypropylene nonwoven
Polyester nonwoven Polyester nonwoven Polyester nonwoven Polyester nonwoven n/a
Geotextile polymer ~nd type
22
9.6
24
3(1
15 20
14 21.5 15 5 15 15 15 15
9
22
9-6
18 26
18
18
n/a n/a 10 21 n/a
1.45 psi
@
22
9-6
n/a
30
15 20
12.6 20 15 n/a n/a 15 15 15
8
n/a
9.6
16 16 16 2-1
n/a nda 2 6 n/a
14.5 psi
@
Flow rate" (gpm/fi)
"Note that these v a l u e s of c o m p r e s s i v e s t r e n g t h are f r o m m a n u f a c t u r e r s ' literature and h a v e b e e n d e r i v e d by d i f f e r e n t test m e t h o d s a n d / o r procedures.
10 Pro Drain Systems
Exxon
5
4
Enkamat 7010 Enkamat 7020 Enkadrain 9010 Enkadrain 9120 Aquadrain 15X
Trademark
Amerdrain480 Amerdrain 500 Amerdrain650 Burcan Industries Hitek 6c
American Colloid Co. 3 American Wick Drain Co.
2
1 Akzo
No.
Core characteristics
TABLE 1 Properties of Commercially Available Geocomposite Sheet Drains as Listed in Manufacturers' Literature L]l
~0
F
t~
bo
503
Geocomposite sheet drain joining
O V E R L A P J O I N I N G OF G E O C O M P O S I T E D R A I N A G E C O R E S For most of the sheet drain cores listed in Table 1, for example, products n u m b e r e d 2, 3, 4, 5, 6, 7, 9 and 10, the joining of panels can be accomplished by a male-to-female overlap connection of the repeat rows of their core structures. Just how many rows are necessary to mobilize the tensile strength of the core is the subject of this experimental study. Tensile tests were performed on 8-0 in (200 mm) wide width sections of the cores and then compared to overlapped joints of the same width incorporating from 1 to 7 rows of the protrusions of the overlapped section. No bonding or gluing of the overlap was performed, although the sheets were resisted from riding up over one another by a low normal stress of 4 kPa (0.5 lb/in2). This was felt to model properly a minimum type of compressive stress in the field. The results are shown in Fig. 1. Here it is seen that the core tensile strength is mobilized quite slowly as the n u m b e r of incorporated rows is increased. For two of the products the protrusions
100
80
J~ O
60
:E J¢:
g
¢D
_¢ 40 p¢1 o
Product "G" •
,I,
]product iT,
20 ConfiningPressure: 4 kPa 1
Numberof Rows Incorporated in the OverlappedJoint Fig. 1. Mobilizationof core tensile strength by overlapped geocomposite sheet drains as a function of number of rows incorporated.
504
Bao-Lin Hwu, Robert M. Koerner 120
_1
100
80
•
Product "M', 3 Rows
•
Product "G', 3 Rows
•
Product "T', 2 Rows
60
"g
g
I
I
40
kS
20
0
0
10
20
30
40
50
60
70
Confining Pressure (kPa)
Fig. 2. Mobilization of core tensile strength by overlapped geocomposite sheet drains under different confining pressures.
laterally d e f o r m e d and the mobilized strength was quite low. However, it must be m e n t i o n e d that most sheet drain systems are generally not u n d e r tension and only must carry enough tensile stress to provide continuity of flow. This is the case for retaining wall and plaza deck drainage, but might not be the case for landfill cap drainage. These same sheet drain cores were further evaluated as to the effect of increasing confining pressure with results given in Fig. 2. H e r e it is seen that greater normal stress rapidly increases the tensile strength of the coupled zone. The 2 or 3 rows of overlapped area often referred to in manufacturers' literature appear to be adequate as the normal pressure is increased. It should be noted, however, that some of the cores listed in Table 1 cannot be joined in the interlocking m a n n e r just described. For these products a friction overlap is required or some type of mechanical coupling of butt-jointed ends. While this decision is product specific, it must be cautioned that liquid flow in the core itself cannot be restricted.
Geocomposite sheet drain joining
505
Wall Retaining Wall
[":B]ti)l~'*" i i ~ i t / FIIter
.t_ /Filter
Fabric
~:7~1~ ..Geocompoilt.
Water-
~..'-.*.ll~ _ .~I,!~i
Proo.ng :~iE ::::&i --
Fabric
Geocompo.lte I S h e e t Dr.ln
Sheet Drain
,:.:.
Native Soil
Native Soil
weep
i:7:]Fl Parlor.ted 7:':.'11;[ Discharge :'*.*:J[;i Pipe
Hole
(b) Retaining Wall
(it) Foundation Wall
Retaining et
:::*:
.Filter Fabric
•.'." ~'. . :.*:
.Geocompo.lta
::::: ,'-**
:!:i::
~
......
',::::'7~" "
VegetalJ on. . . . . . . Soll
praln
Sheet Drain
l
Native Soil Perforated
/Oiich.rg.
i!ii! ,/Pip. (c) Retaining Wall
Pipe
:iiiiiit :.:.*.~
/ /
/G.ocolmpoilte
Sheet Drain
Anti-Root Layer
i!:.'ili'*'*'*t Waterproofing
(d) Plaza (Deck)
Drain
Fig. 3. Various outlet details for geocomposite sheet drains (from various manufacturers).
O U T L E T D E T A I L S OF G E O C O M P O S I T E S H E E T D R A I N S For most applications of geocomposite sheet drains, the core conveys liquid to a drainage outlet which is often a perforated pipe. This connection is a critical detail and must be done in a careful and workmanlike manner. Since the variations are somewhat product specific we have collected a set of manufacturers' suggestions and presented them in Fig. 3. They have been found to be successful via past practice and are recommended for continued use. Note that the geotextile wrapping of the completed core-to-pipe connection is an extremely important detail. Without complete geotextile coverage of both the drainage core and the perforated pipe, soil intrusion can block the entire flow system at its most critical location, i.e. at its exit.
506
Bao-Lin Hwu, Robert M. Koerner
SUMMARY This brief paper has focused on geocomposite sheet drain joining and connections. Since most of the drainage core products are vacuum formed in their fabrication they have a natural male-to-female joining capability. It was shown experimentally that 2 or 3 rows of repeat units are generally sufficient to mobilize the core's tensile strength. Other core types must be evaluated on a product-specific basis. The outlet connection for the liquid conveyed in the core, which is usually via a perforated pipe, was also addressed. Various manufacturers' schemes were presented where it was seen that workmanship and complete geotextile encapsulation of the drainage components are critical aspects of the various types of connection.