Drainage System Of Pavements
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PAVEMENT DRAINAGE
PRESENTED BY : KAZIM KHAN (05-CTE-26) SYED ABID MASOOD (05-CTE07)
CONTENTS
Related Terms & Definitions
Why is road drainage so importants ?
Factors Affecting the drainage system in road construction
Sources of Moisture in Pavements
PART 1
Related Terms & Definitions
Pavement: All elements from the wearing surface of a roadway to the subgrade.
Permeable base: A free draining layer in the pavement designed to rapidly remove free water from most elements of pavement.
Base crossdrain: A subsurface drain, generally perpendicular to the roadway alignment, designed to drain infiltrated water.
Dense-graded aggregate base (DGA): Mixture of primarily sand and gravel, well-graded from coarse to fine (usually unstabilized, but sometimes asphalt or cement
Related Terms & Definitions
Drainage aggregate: Open-graded aggregate with high permeability.
Drainage pipe: Rigid or flexible pipe conduit designed to collect and/or transport water out of the pavement section (usually perforated).
Edgedrain: A subsurface drain usually located at the edge of the pavement.
Headwall:
Related Terms & Definitions
Infiltration: Free water in the pavement structural elements entering through cracks, joints, or permeable paving.
Outlet: The point of discharge of an edgedrain.
Outlet pipe: The lateral connection from the edgedrainto the outlet. Usually a solid pipe and usually strong to prevent damage.
Related Terms & Definitions
Prefabricated geocomposite edgedrain (PGED): An edgedrain consisting of a drainage core covered with geotextile. Usually 1 to 2 in. thick by 1 to 3 ft high, placed in a narrow trench. It may include drainage aggregate or sand as a part of the installation.
Separator/filter layer (aggregate or geotextile): A geotextile or aggregate (subbase) layer separating a permeable base layer from an adjacent soil (or aggregate) containing fines to prevent the fines from contaminating the drainage aggregate. Must meet the filter criteria for drainage filters.
Underdrain: A deep subsurface drain located at a sufficient depth to intercept and lower the ground water to a required design
Related Terms & Definitions
Capillary action The flow of liquids through porous media & movement of liquids in thin tubes.
Vapor movement The process by which the entire body of fluid moves in responses to differences in hydraulic potentials.
Seepage The process by which a liquid leaks through a porous substance.
WHY IS ROAD DRAINAGE SO IMPORTANTS ?
A road’s infrastructure is an engineering work, aiming the establishment of a platform, on which vehicle circulation is possible under safety conditions, proper traffic flow, commodity, and economy, independently of the region’s climate conditions;
Water, along with heavy traffic, is one of the greatest causes of road ruin.
Subsurface Drainage Importance
Soil’s resistance to compression may drop from 0.15 MPa to 0.07 MPa (about half) if its water content increases from 25 to 30%.
Factors Affecting the drainage system in road construction
Sensitivity of groundwater
Importance of road
Area (rural or populated)
Amount of traffic
Sensitivity of streams, rivers, lakes
Sources of Moisture in Pavements
Sources of Moisture in Pavements
Sources of Moisture in Pavements
Flow of existing sub-surface water, from higher terrain near the road
Elevation or drop of the water table
Water infiltration by joints or badly sealed cracks (concrete pavement) or by porous and fissured areas
Moisture movement on the soil
Successive frost/defrost cycles, increase cracks and therefore water infiltration on the pavement
Sources of Moisture
PCC Pavement Water Infiltration
Moisture-Related and Accelerated Distresses
Pumping/erosion.
Faulting.
Corner cracking.
Transverse cracking.
Fatigue (alligator)
Purpose of Subsurface Drainage
Subsurface drainage is intended to remove water that infiltrates into a pavement.
Surface water is primarily removed through proper geometric design.
Water can enter the pavement in numerous ways,
only some of which can be effectively drained by a subsurface drainage system.
The basic idea is that water in the pavement drives certain types of distress.
Fac Purpose of Subsurface Drainage
Amount of free water that infiltrates into the pavement structure.
Potential for moisture-related damage to pavement.
Ability to design, construct, and maintain the drainage system.
Other general factors (e.g., topography, soil types,etc.).
Components of a Pavement Drainage System
Components of a Pavement Drainage System
Stress distribution Pattern
Stress distribution in dry pavement layer
Stress distribution in saturated pavement layer
PART 2
TYPES OF DRAINAGE SYSTEMS
Transversal Drainage
Transversal Drainage
Slab culverts
Pipe culverts
Cause ways
Longitudinal Drainage
Gutters, ditches and channels;
Galleries, collectors and drains;
Connection and Collecting Accessory organs, namely visit and cleaning chambers;
Reception chambers, connection or derivation boxes.
Longitudinal Drainage
Sub-surface drainage Main types of devices
2. Longitudinal interception drains 4. Longitudinal water table lowering drains 6. Transversal drains 8. other devices
Drainage layers Draining spurs Draining masks Sub-surface drainage Longitudinal drains in ½ hillsid Christmas tree drain Cutting drain
1. Longitudinal interception drains
Longitudinal Edgedrains Runs
parallel to the traffic lane
Collect
water that infiltrates the pavement surface and drains water away from the pavement through outlets
Types of edgedrains systems
1. Pipe edgedrains in an aggregate filled trench, 3. Pipe edgedrains with porous concrete (i.e., cement treated permeable base) filled trench, 5. Prefabricated geocomposite edgedrains in a sand backfilled trench, and
Figure 7-6. Typical edgedrains for rehabilitation
Longitudinal Edgedrains
Typical AC pavement with pipe edgedrains
Typical PCC pavement with geocomposite edgedrains
Typical edgedrains for rehabilitation projects
2. Longitudinal water table lowering drains
3. Transversal drains
Drainage layers
Longitudinal drains in ½ hillside
Cutting drain
Christmas tree drain
Draining Spurs
A small ridge that projects sharply from the side of a larger hill or mountain
Draining masks
Horizontal Geocomposite Drainage Layers
Drainage in PCC Pavement System
Pre-pave installatio n
Post-pave installatio n
Comprehensive Drainage System Components
CONTAMINATION/ PUMPING
AGGREGATE PENETRATION
AASHTO Drainage Definitions
*Based on time to drain AASHTO Guide for Design of Pavement Structures
Design of Pavement Drainage
The hydraulic requirements for the permeable layer to achieve the required time-to-drain.
The edgedrain pipe size and outlet spacing requirements.
Either the gradation of requirements for a graded aggregate separation layer or the opening size, permeability, endurance, and strength requirements for geotextile separators.
The opening size, permeability, endurance, and strength requirements for geotextile filters, or the gradation of the granular filters (to be used in the edgedrain).
Sub-surface drainage Hydraulic calculation for drains (QL)
QL = q . B . L QL - water flow through the pipe (m3/s) q - surface run-off water flow (m3/s/m) L - sect ion's length [m] B - width calculation's [m]
Sub-surface drainage Hydraulic calculation for drains (QL)
In cases where the drainage is used not only as interception drainage but also to lower the water level, dimensioning should consider specific calculations for the underground flow in to the drain. In this situation the projected flow should be the sum of the aforementioned value and the estimate through the application of Darcys’ Law.
In order to simplify dimensioning, some authors consider that the in-flow to the drain amounts to about 35% of the total flow generated in banks added by 20% for flow originated in the road platform, i.e.: QL = 0.35×QT + 0.20×Qp
QL– water flow to de pipe (m3/s); QT – surface run-off water in slopes (m3/s);
Sub-surface drainage Hydraulic calculation for drains (QL) 0.5
As to the depth of installation of the drains, one can estimate, in a first approach, by the formula: 0.5
D – drain depht (m) d – depth that groundwater level should stabilize(m) b – distance between drains(m) i – infiltration soil rate (m/s) K – soil permeability (m/s)
Sub-surface drainage
Hydraulic calculation for drains (QL)
The capacity of a circular pipe flowing full can be determined by Manning's equation:
Q = (53.01/n) D8/3 S1/2 where, Q = Pipe capacity, cu ft/day D = Pipe diameter, in. S = Slope, ft/ft n = Manning's roughness coefficient
Refrences
http://www.usroads.com/journals/rmej.htm
http://pavementinteractive.org/index.php?title=Surface_Drainage
www.fhwa.dot.gov/.../geotech/pubs/05037/07a.cfm
http://en.wiktionary.org/wiki/seepage
http://books.google.com/
QUESTIONS ? THANK S
PRESENTED BY : KAZIM KHAN (05-CTE-26) SYED ABID MASOOD (05-CTE07)
CONTENTS
Related Terms & Definitions
Why is road drainage so importants ?
Factors Affecting the drainage system in road construction
Sources of Moisture in Pavements
PART 1
Related Terms & Definitions
Pavement: All elements from the wearing surface of a roadway to the subgrade.
Permeable base: A free draining layer in the pavement designed to rapidly remove free water from most elements of pavement.
Base crossdrain: A subsurface drain, generally perpendicular to the roadway alignment, designed to drain infiltrated water.
Dense-graded aggregate base (DGA): Mixture of primarily sand and gravel, well-graded from coarse to fine (usually unstabilized, but sometimes asphalt or cement
Related Terms & Definitions
Drainage aggregate: Open-graded aggregate with high permeability.
Drainage pipe: Rigid or flexible pipe conduit designed to collect and/or transport water out of the pavement section (usually perforated).
Edgedrain: A subsurface drain usually located at the edge of the pavement.
Headwall:
Related Terms & Definitions
Infiltration: Free water in the pavement structural elements entering through cracks, joints, or permeable paving.
Outlet: The point of discharge of an edgedrain.
Outlet pipe: The lateral connection from the edgedrainto the outlet. Usually a solid pipe and usually strong to prevent damage.
Related Terms & Definitions
Prefabricated geocomposite edgedrain (PGED): An edgedrain consisting of a drainage core covered with geotextile. Usually 1 to 2 in. thick by 1 to 3 ft high, placed in a narrow trench. It may include drainage aggregate or sand as a part of the installation.
Separator/filter layer (aggregate or geotextile): A geotextile or aggregate (subbase) layer separating a permeable base layer from an adjacent soil (or aggregate) containing fines to prevent the fines from contaminating the drainage aggregate. Must meet the filter criteria for drainage filters.
Underdrain: A deep subsurface drain located at a sufficient depth to intercept and lower the ground water to a required design
Related Terms & Definitions
Capillary action The flow of liquids through porous media & movement of liquids in thin tubes.
Vapor movement The process by which the entire body of fluid moves in responses to differences in hydraulic potentials.
Seepage The process by which a liquid leaks through a porous substance.
WHY IS ROAD DRAINAGE SO IMPORTANTS ?
A road’s infrastructure is an engineering work, aiming the establishment of a platform, on which vehicle circulation is possible under safety conditions, proper traffic flow, commodity, and economy, independently of the region’s climate conditions;
Water, along with heavy traffic, is one of the greatest causes of road ruin.
Subsurface Drainage Importance
Soil’s resistance to compression may drop from 0.15 MPa to 0.07 MPa (about half) if its water content increases from 25 to 30%.
Factors Affecting the drainage system in road construction
Sensitivity of groundwater
Importance of road
Area (rural or populated)
Amount of traffic
Sensitivity of streams, rivers, lakes
Sources of Moisture in Pavements
Sources of Moisture in Pavements
Sources of Moisture in Pavements
Flow of existing sub-surface water, from higher terrain near the road
Elevation or drop of the water table
Water infiltration by joints or badly sealed cracks (concrete pavement) or by porous and fissured areas
Moisture movement on the soil
Successive frost/defrost cycles, increase cracks and therefore water infiltration on the pavement
Sources of Moisture
PCC Pavement Water Infiltration
Moisture-Related and Accelerated Distresses
Pumping/erosion.
Faulting.
Corner cracking.
Transverse cracking.
Fatigue (alligator)
Purpose of Subsurface Drainage
Subsurface drainage is intended to remove water that infiltrates into a pavement.
Surface water is primarily removed through proper geometric design.
Water can enter the pavement in numerous ways,
only some of which can be effectively drained by a subsurface drainage system.
The basic idea is that water in the pavement drives certain types of distress.
Fac Purpose of Subsurface Drainage
Amount of free water that infiltrates into the pavement structure.
Potential for moisture-related damage to pavement.
Ability to design, construct, and maintain the drainage system.
Other general factors (e.g., topography, soil types,etc.).
Components of a Pavement Drainage System
Components of a Pavement Drainage System
Stress distribution Pattern
Stress distribution in dry pavement layer
Stress distribution in saturated pavement layer
PART 2
TYPES OF DRAINAGE SYSTEMS
Transversal Drainage
Transversal Drainage
Slab culverts
Pipe culverts
Cause ways
Longitudinal Drainage
Gutters, ditches and channels;
Galleries, collectors and drains;
Connection and Collecting Accessory organs, namely visit and cleaning chambers;
Reception chambers, connection or derivation boxes.
Longitudinal Drainage
Sub-surface drainage Main types of devices
2. Longitudinal interception drains 4. Longitudinal water table lowering drains 6. Transversal drains 8. other devices
Drainage layers Draining spurs Draining masks Sub-surface drainage Longitudinal drains in ½ hillsid Christmas tree drain Cutting drain
1. Longitudinal interception drains
Longitudinal Edgedrains Runs
parallel to the traffic lane
Collect
water that infiltrates the pavement surface and drains water away from the pavement through outlets
Types of edgedrains systems
1. Pipe edgedrains in an aggregate filled trench, 3. Pipe edgedrains with porous concrete (i.e., cement treated permeable base) filled trench, 5. Prefabricated geocomposite edgedrains in a sand backfilled trench, and
Figure 7-6. Typical edgedrains for rehabilitation
Longitudinal Edgedrains
Typical AC pavement with pipe edgedrains
Typical PCC pavement with geocomposite edgedrains
Typical edgedrains for rehabilitation projects
2. Longitudinal water table lowering drains
3. Transversal drains
Drainage layers
Longitudinal drains in ½ hillside
Cutting drain
Christmas tree drain
Draining Spurs
A small ridge that projects sharply from the side of a larger hill or mountain
Draining masks
Horizontal Geocomposite Drainage Layers
Drainage in PCC Pavement System
Pre-pave installatio n
Post-pave installatio n
Comprehensive Drainage System Components
CONTAMINATION/ PUMPING
AGGREGATE PENETRATION
AASHTO Drainage Definitions
*Based on time to drain AASHTO Guide for Design of Pavement Structures
Design of Pavement Drainage
The hydraulic requirements for the permeable layer to achieve the required time-to-drain.
The edgedrain pipe size and outlet spacing requirements.
Either the gradation of requirements for a graded aggregate separation layer or the opening size, permeability, endurance, and strength requirements for geotextile separators.
The opening size, permeability, endurance, and strength requirements for geotextile filters, or the gradation of the granular filters (to be used in the edgedrain).
Sub-surface drainage Hydraulic calculation for drains (QL)
QL = q . B . L QL - water flow through the pipe (m3/s) q - surface run-off water flow (m3/s/m) L - sect ion's length [m] B - width calculation's [m]
Sub-surface drainage Hydraulic calculation for drains (QL)
In cases where the drainage is used not only as interception drainage but also to lower the water level, dimensioning should consider specific calculations for the underground flow in to the drain. In this situation the projected flow should be the sum of the aforementioned value and the estimate through the application of Darcys’ Law.
In order to simplify dimensioning, some authors consider that the in-flow to the drain amounts to about 35% of the total flow generated in banks added by 20% for flow originated in the road platform, i.e.: QL = 0.35×QT + 0.20×Qp
QL– water flow to de pipe (m3/s); QT – surface run-off water in slopes (m3/s);
Sub-surface drainage Hydraulic calculation for drains (QL) 0.5
As to the depth of installation of the drains, one can estimate, in a first approach, by the formula: 0.5
D – drain depht (m) d – depth that groundwater level should stabilize(m) b – distance between drains(m) i – infiltration soil rate (m/s) K – soil permeability (m/s)
Sub-surface drainage
Hydraulic calculation for drains (QL)
The capacity of a circular pipe flowing full can be determined by Manning's equation:
Q = (53.01/n) D8/3 S1/2 where, Q = Pipe capacity, cu ft/day D = Pipe diameter, in. S = Slope, ft/ft n = Manning's roughness coefficient
Refrences
http://www.usroads.com/journals/rmej.htm
http://pavementinteractive.org/index.php?title=Surface_Drainage
www.fhwa.dot.gov/.../geotech/pubs/05037/07a.cfm
http://en.wiktionary.org/wiki/seepage
http://books.google.com/
QUESTIONS ? THANK S
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