1、Designation: D 7498 09Standard Test Method forVertical Strip Drains Using a Large Scale ConsolidationTest1This standard is issued under the fixed designation D 7498; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method is a performance test, which measuresthe effectiveness of vertical strip drains on the time rates ofconsol
3、idation of compressible soils from construction projectsites.1.1.1 It is expected that the design agency will be respon-sible for performing this test. It is not intended to be amanufacturer performed test.1.2 This test method is applicable to all vertical strip drains.1.3 The values stated in SI un
4、its are to be regarded as thestandard. No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health
5、 practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 4354 Practice for Sampling of Geosynthetics for TestingD 4439 Terminology for Geosynthetics3. Terminology3.1 DefinitionsFor definitions related to geosynthetics,see Termino
6、logy D 4439.3.2 Definitions of Terms Specific to This Standard:3.2.1 vertical strip drains, na geocomposite consisting ofa geotextile cover and drainage core installed vertically intosoil to provide drainage for accelerated consolidation of soils.4. Summary of Test Method4.1 This test method describ
7、es procedures for determiningthe effectiveness of vertical strip drains used under specifiedsoil conditions to enhance the time rate of consolidation ofcompressible soils.4.2 A specimen of the vertical strip drain is inserted in thetest chamber and compressible soil from the project site isremolded
8、around the vertical strip drain, such that the drain isin a similar position as it would be on the project site.4.3 The top of the soil is sealed with a wax seal, such thatdrainage only occurs through the vertical strip drain. Thevertical strip drain protrudes up through the seal.4.4 Asand drainage
9、blanket is placed on top of the wax seal,such that the vertical strip drain drains into the sand blanket.4.5 A rubber cup seal provides the means of applyingincremental loads in a similar manner to a standard soilsconsolidation test.4.6 A similar setup is used, only with a 50 mm (2 in.) sanddrain in
10、 place of the vertical strip drain.4.7 The Coefficients of Consolidation are determined fromthe test results for both the vertical strip drain and the sanddrain. Time rates of consolidation are then compared.4.8 Persons performing this test shall have knowledge in theconsolidation testing of soils.5
11、. Significance and Use5.1 As this is a time intensive test, it should not beconsidered as an acceptance test for commercial shipments ofprefabricated vertical strip drains.5.2 Prior to the development of vertical strip drains, when itwas desired to increase the rate of consolidation of a compress-ib
12、le soil on a construction project, large diameter sand drainswere installed. Vertical strip drains can be installed in areaswhere it is desired to increase the rate of soils consolidation inplace of these large diameter sand drains.5.3 This test method can be used to compare the perfor-mance of vert
13、ical strip drains to that of sand drains.1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D35.03 on Perme-ability and Filtration.Current edition approved June 1, 2009. Published July 2009.2For referenced ASTM standards
14、, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19
15、428-2959, United States.6. Apparatus6.1 The apparatus for this test method is a specialty piece ofequipment that must be capable of safely handling loads up to206.8 kPa (30 psi) using compressed air.6.1.1 As this is a time intensive test, it is recommended tohave three test apparatus setups. This wi
16、ll allow simultaneoustesting of three vertical strip drain specimens.6.1.2 Test ChamberA 254.0-mm (10-in.) diameter by558.6-mm (22-in.) high by 12.7-mm (0.5-in.) wall thicknessPVC pipe. (Fig. 1)6.1.2.1 Drainage PortsSix 3.18-mm (0.125-in.) drainageports are located 152.4-mm (6-in.) from the top, and
17、 equallyspaced around the perimeter of the cylinder.6.1.2.2 On the outside of the cylinder, at 180 to oneanother, two 19.05-mm (0.75-in.) thick acrylic hooks arelocated 25.4 mm (1 in.) from the bottom of the test chamber forthe purpose of fastening the test chamber to the base plate.6.1.3 Base Plate
18、:A 361.95-mm (14.25-in.) diameter PVC flat plate, 38.1 mm(1.5 in.) thick.6.1.3.1 The base plate has a 12.7-mm (0.5-in.) wide by6.35-mm (0.25-in.) deep concentric groove, having an insidediameter of 254.0 mm (10 in.), located on the top side of thebase plate.6.1.3.2 A 3.17-mm (0.125-in.) by 228.6-mm
19、(9-in.) diam-eter rubber O-ring is stretched and placed in this groove.FIG. 1 Large Scale ConsolidatorD74980926.1.3.3 The test chamber is seated into the groove on top ofthe O-ring.6.1.4 Tension Rods:Equally spaced around the base plate, 158.75 mm (6.25 in.)from the center of the plate, are six 0.95
20、2-mm (0.375-in.)diameter by 76.2-mm (30-in.) long threaded tension rods.6.1.4.1 Each tension rod is attached to the base plate by twohex nuts, one above the plate, and one beneath.6.1.4.2 On two 180 opposing tension rods place a wing nutthat is used to secure the test chamber to the base plate via t
21、hehooks referred to in 6.1.2.2.6.1.5 Double Cup Seal Assembly:This is used to evenly distribute the consolidation load overthe soil in the test chamber. It consists of the following parts:6.1.5.1 Two 254.00-mm (10-in.) diameter by 4.76-mm(0.3125-in.) thick rubber cup seals that are placed back to ba
22、ck.They are sandwiched between two 241.3-mm (9.5-in) diameterby 12.7-mm (0.5-in) flat PVC plates.6.1.5.2 A 12.7-mm (0.5-in.) diameter by 228.6-mm (9-in.)long center rod centrally located on the cup seal assembly. It isattached to the assembly by a ball and socket device.6.1.5.3 A removable PVC platf
23、orm that is attached to thecenter rod after the test chamber is completely assembled. Thisis used to seat the deflection dial or transducer on.6.1.6 Top Plate:an identical plate to the base plate, including the groove fortest chamber seating, and holes for tension rods to go through.6.1.6.1 A 3.17-m
24、m (0.125-in.) by 228.6-mm (9-in.) diam-eter rubber O-ring is stretched and placed in the groove.6.1.6.2 A threaded 6.35-mm (0.25-in.) diameter hole goingcompletely through the top plate into which a brass fitting ismounted. The air supply line is attached to this fitting. Theconsolidation loads are
25、applied through this air line.6.1.6.3 The double cup seal assembly is mounted through ahole in the center of the top plate. The cup seals are placed suchthat they will be inside the test chamber.6.1.6.4 Apressure gauge for reading the applied air pressureis mounted to the top plate such that it read
26、s the pressure insidethe test chamber.6.1.7 Adeflection dial or electronic displacement transducergraduated in 0.0254-mm (0.001-in.) divisions.6.1.7.1 The deflection measuring device is attached to thetop plate by mounting it on a rod mounted to the outer edge ofthe top plate.6.1.8 Vertical Strip Dr
27、ain Mount:A flat PVC plate cut to fit the inside of the test chamber.NOTE 1See Fig. 1 and Fig. 2 for schematic diagrams of the testapparatus.7. Materials7.1 Project Soil:A quantity of in-situ compressible soil large enough toperform the number of required tests shall be obtained from theproject site
28、. This does not have to be undisturbed soil.NOTE 2The quantity of soil needed shall be figured based on fillingthe test chamber to a height of 381 mm (15 in.) at the desired density.7.2 Silicone Spray:The spray is used to lubricate the inside surface of the testchamber to minimize friction between t
29、he soil and the chambersurface.8. Hazards8.1 There are no known hazards with the materials, or inperforming the test.9. Sampling, Laboratory Samples, and Test Specimens9.1 Lot SampleAs a lot sample for acceptance testing,take the number of units as directed in Table 3 in PracticeD 4354. Consider rol
30、ls of the vertical strip drain to be theprimary sampling units.9.2 Laboratory SampleTake for the laboratory sample asample 1829 mm (72 in.) in length from each of the lotsamples. Before taking the laboratory sample, remove the outerlayer of drain from the sample roll to avoid testing anydamaged mate
31、rial.9.3 Test SpecimensFrom each laboratory sample cut threetest specimens, each 508.0 mm (20 in.) long, making sure eachend of the specimen is cut square.9.3.1 At one end of each test specimen cut three notches6.35 mm (0.25 in) x 12.7 mm (0.5 in) long. Each notch shouldline up with the mounting bol
32、ts in the specimen mount. SeeFig. 1.9.3.2 Place a 25.4-mm (1-in.) wide piece of masking tapearound each test specimen, covering the area from 374.6 mm to400.0 mm (14.75 to 15.74 in.) of the length of each specimen.10. Test Set-Up10.1 Compute the total wet mass of soil to be used in eachchamber by mu
33、ltiplying the desired wet density by the volumethe soil will occupy. This is the initial mass of soil.10.2 Taking a small portion of the wet soil from 10.1,determine and record the initial moisture content of the soil tobe placed in the test chamber using Eq 1.wi5 WT WS!/W 3 100 % (1)where:wi= Initi
34、al Moisture Content (%)WT= Total Wet Mass of Soil (g)WS= Dry Mass of Soil (g)10.3 Secure the test chamber to the bottom base makingsure that the O-ring seal is in place in the base plate.10.4 Draw a line around the inside of the test chamber 381.0mm (15 in.) up from the top surface of the base plate
35、. This isthe height to which the soil will be placed, and is the initialheight of soil in the test chamber.10.5 Spray non-stick silicone spray around the inside sur-face of the test chamber. This will reduce sidewall fictionbetween the soil and the test chamber as consolidation takesplace.10.6 Assem
36、ble the test specimen to the specimen mountingplate by placing the three pre-cut notches over the assemblybolts and tightening these bolts. Place the assembly in the testchamber.10.7 Weigh and record the test chamber, bottom base plate,prefabricated vertical strip drain and holder, and assembly rods
37、weight.D749809310.7.1 Leaving the items in 10.6 on the scale, tare the scaleout.NOTE 3If the scale can be locked, lock the platform in place aftertaring out. Then set the scale for the desired mass of soil to be added inthe next step.10.8 Soil PlacementHolding the prefabricated verticalstrip drain i
38、n a vertical position, start placing the soil into thetest chamber. Distribute evenly around the drain using handpressure and kneading to eliminate voids and achieve auniform density. Add soil in layers of equal thickness until thefinal placed layer reaches the line drawn in 10.4. Be sure tokeep the
39、 test specimen in a vertical position as the chamber isfilled with soil.10.8.1 The moisture content, percent saturation, and place-ment density shall be as required by specifier.10.8.2 Clean any excess soil from the walls of the testchamber and then unlock the scale and check to see that thedesired
40、mass of soil has been placed in the chamber.10.9 Apply another coating of non-stick silicone spray tothe inside exposed test chamber wall.10.10 Place a 9.52-mm to 12.7-mm (0.375 to 0.5-in.) layerof molten wax on the entire top surface of the soil, allowing itto seal against the taped section of the
41、test specimen. Makesure that wax does not splash on exposed portion of testspecimen or the walls of the test chamber.10.11 With a thin bladed spatula carefully cut around theperimeter of the test chamber between the wax seal and thewall to break any bonding of the seal to the wall.10.12 Place a unif
42、orm 25.4-mm (1-in.) layer of moist silicasand on top of the hardened wax seal. Fold the test specimenwhich extends up through the sand layer over on top of thesand. Place an additional 76.2-mm (3-in.) layer of moist silicasand over the test specimen. Level and smooth the surface ofsand.NOTE 4Be care
43、ful not to crimp the test specimen or break the waxseal when bending the specimen over the sand.10.12.1 Record the height of the sand layer.10.13 Place the double cup seal assembly inside the cylin-der. Be sure that it is level and in contact with the sand layer.10.13.1 Place the top plate down over
44、 the center rod of thecup seal assembly and tension rods on the cylinder. Be sure thatthe O-ring seal is in place in the top plate.10.14 Connect an air line from the air supply to the fitting inthe top plate.FIG. 2 Prefricated Vertical Strip Drain MountD749809410.15 Attach the deflection dial or tra
45、nsducer platform tothe center rod.10.15.1 Attach the deflection dial or transducer to the topplate, being sure that the follower of the dial or transducer iscontact with platform in 10.14.10.15.2 Set up remaining two test chambers in the samemanner.11. Test Procedure11.1 With the air supply valves i
46、n the off position, adjust theair regulators to read 103.42 kPa (15 psi), or as otherwisespecified, but within the safe operating limits of the air supplysystem.11.2 Record the initial, or zero load, deflection dial/transducer readings.11.3 Open air supply valves so that the air pressure from11.1 is
47、 applied to the test soil.11.4 Take the following timed deflection readings:11.4.1 Day 1: 1,2,5,10,30,45,60,90,120,150,180,210,240,then hourly;11.4.2 Day 2: Morning; Mid-day; End of the work day.11.4.3 Remainder of the test: Morning; End of the work day.NOTE 5If electronic timing and data collection
48、 are used, after the firstday, readings every six hours are suggested.11.5 The following plots are constructed during the testphase: 1) Deflection readings versus the log of elapsed time;and 2) Deflection readings versus the square root of time.NOTE 6These plots will be used to determine the ending
49、of eachloading phase.11.6 When the plots from 11.5 show that there are a leastthree data points beyond the 100 % primary consolidationphase for the soil, proceed to the next loading phase.11.7 With the air supply valves in the off position, adjust theair regulators to 206.84 (30 psi), or as otherwise specified, butwithin the safe operating limits of the air supply system.11.8 Repeat 11.2-11.6.11.9 When the plots for the second load meet the conditionof 11.6, the test is complete.11.10 Shut off the air supply and release the load from thesoil.11.10.1 Remove the top
