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separation reinforcement filtration surface protection
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Term
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a crack in pavement because the pavement it is on also cracked there.
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Term
Woven vs non-woven geotextiles
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Definition
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woven: threads wound together become yarn, yarns woven form warp and weft. Fabric is weakest and least flexible in direction of yarns. # of yarns=thread count. Can also have finish. non-woven: mechanical entanglement, chemical bonding or thermal bonding. long threads or short. often needle punched to increase permiability. evenly strong and stretchy in all directions.
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Term
most important properties for geotextiles in landscape applications
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Definition
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thickness and porosity. then roughness
thicker=stronger but get clogged. Porosity units:EOS(Equivalent opening size), corresponds to sieve size. rougher=slows down water more, grips earth as a deadman better.
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Term
three mechanical properties of geotextile fabric
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Definition
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elongation: %+ length when fully extended Grab Strength: LBs required to pull it apart. Burst pressure: pressure req to burst a section
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Term
factors in geotextile selection
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Definition
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filtering(clogging) permeability k pore size(EOS) moisture absorption(esp. with natural fibers) chemical resistance(fertlzr,org.soil,+PHsoil,oil,asph) UV resistance tensile strength and extensibility(uneven, steep) thickness different soils on each side connection details(seams,
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Term
geotextile applications-separation
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Definition
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roadway and railway beds(between subgrade and subbase) Earth dam(many different materials to separate planters (drainage medium from growing medium) formwork (mat or tube forms, like an air matress. Good for inaccessibile places, or "sandbags")
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Term
| Applications for geotextiles-reinforcement |
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Definition
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-paving(prevent reflection cracks w/ a tack coat) -retaining walls(tie-backs anchor facing unitsusing weight of ground behind the wall to hold facing units -Slopes(steeper than angle of repose. used w/ plants: horizontal pieces every 2 feet, soil compacted. -Roadways(compressible fabrics reduce amnt of aggregate base. maintain proper drainage, separate materials. increases load bearing. -turf( 3-D geotextiles. distribute weight to subgrade, don't compact grass. Can also just mix long fibers into soil.
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Term
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Definition
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California Bearing Ratio ability of soil to resist a load.
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Term
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Definition
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weight on pavement squishing subgrade down into soil and vica versa
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Term
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Definition
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-minimum fabric permeability to not inhibit soil drainage: more than .1 K of the soil(the permeabiity of the soil itself) Ideal fabric permeability: greater than or equal to K, unless soil held by electrochemical forces(then up to 5XK) -piping prevention for soils under 50% silt: EOS fabric is less than 2X the sieve size that lets through 85% of the soil. For soils over 50% silt: EOS fabric is less than 1X sieve size that allows 85% To prevent clogging, EOS min= 100 or open area of 4%. according to engeneers.
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Term
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Definition
soil squeezing through geotextile. Prevented by buildup of "filter cake" of fine particles that build up next to filterfabrics.
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Term
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Definition
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trapazoidal channel with flat bottom sized to convey a 2 year storm volume below erosion speeds(4-5 ft/sec) and total volume to accomodate ten year rainfall w/o erosion(7ft/sec) For water quality: max speed 1ft/sec, water must go at least 10'. bottom shouldn't be mroe than 6' wide to prevent braiding.
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Term
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Definition
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Planned Unit Development. both a type of building development as well as a regulatory process. A PUD is a designed grouping of varied and compatible land uses, such as housing, recreation, commercial centers, and industrial parks, all within one contained development or subdivision. credited to Prince Georges County, Maryland in 1949. hierarchy of street types, openspace, commercial, industrial, variety of housing all mixed.
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Term
infiltration well spacing
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Definition
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2-4' above high water table. 3' above bedrock(to prevent pollution). 100' from wells. 10' from buildings. Bottom of infiltration bed below frost line. Soils' min infiltration rate must be more than .27"/hr
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Term
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Definition
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water quality volume. Qality treatements that accomodate this volume of water(1.25", generally) will catch most pollution in a given year. Can be calculated w/ Schueler's short cut method(Vilumetric runoff coefficient(Rv)=.05+.009*I(%watershed imperviousness). WQV=design rainfall amnt(P)*Rv) or small stomr hydrology WQV method(same formula with values from a table, runoff coefficient). swales, etc designed to aacomodate this amnt.
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Term
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Definition
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vertical:30 degrees horizontal: 60 degrees
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Term
Stairway dimensions Widths tread-riser ratios height between landings |
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Definition
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min width for public: 42" ratio constant for any stairway. 2*Riser+Tread=26-27". 4.5<R<6 no single steps. at least 2, pref. 3, marked w. handrail, lights, stripes, etc. Pitch tread 2% downward for drainage. space between landings: 10vert.'. 5' pref!
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Term
| performance specification |
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Definition
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specifies no method, just requirements for the final prduct's performance. It is up to the contractor to pick a method that will fulfill the requirements. As opposed to Prescriptive specification.
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Term
prescriptive specification
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Definition
a spec with specific instructions and methods for the contractor, not just requirements for the final product.
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Term
ramps: min width max slope curb cuts max slope distance btw landings |
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Definition
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min width-3' for one-way, 5'for 2-way, more for wheelchairs max slope: 1:12 (8.44%)
curb cuts max slope-1:8(12%) distance btw landings-30'
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