1、Designation: D7498/D7498M 09 (Reapproved 2014)1Standard Test Method forVertical Strip Drains Using a Large Scale ConsolidationTest1This standard is issued under the fixed designation D7498/D7498M; the number immediately following the designation indicates theyear of original adoption or, in the case
2、 of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEUnits information and designation were corrected and editorial changes were made throughout in Febr
3、uary 20141. Scope1.1 This test method is a performance test, which measuresthe effectiveness of vertical strip drains on the time rates ofconsolidation 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 i
4、s 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 either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem
5、 shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.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 a
6、ppro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D4354 Practice for Sampling of Geosynthetics and RolledErosion Control Products(RECPs) for TestingD4439 Terminology for Geosynthetics3. Terminolo
7、gy3.1 DefinitionsFor definitions related to geosynthetics, seeTerminology D4439.3.2 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 consolid
8、ation of soils.4. Summary of Test Method4.1 This test method describes 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 the
9、test chamber and compressible soil from the project site isremolded 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. Theve
10、rtical strip drain protrudes up through the seal.4.4 Asand drainage 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
11、.4.6 A similar setup is used, only with a 50 mm 2 in. sanddrain in 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 thi
12、s test shall have knowledge in theconsolidation testing of soils.5. 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 it
13、was desired to increase the rate of consolidation of a compress-ible soil on a construction project, large diameter sand drainswere installed. Vertical strip drains can be installed in areas1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibi
14、lity of Subcommittee D35.03 on Perme-ability and Filtration.Current edition approved Jan. 1, 2014. Published February 2014. Originallyapproved in 2009. Last previous edition approved in 2009 as D749809. DOI:10.1520/D7498_D7498M-09R14E01.2For referenced ASTM standards, visit the ASTM website, www.ast
15、m.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.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1where it i
16、s 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 vertical strip drains to that of sand drains.6. Apparatus6.1 The apparatus for this test method is a specialty piece ofequipment that must
17、 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 will allow simultaneoustesting of three vertical strip drain specimens.6.1.2 Test ChamberA 254.0-mm 10-in. diameter by558
18、.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 equallyspaced around the perimeter of the cylinder.FIG. 1 Large Scale ConsolidatorD7498/D7498M 09 (2014)126.1.2.2 On the outside
19、 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:6.1.3.1 A 361.95-mm 14.25-in. diameter PVC flat plate,38.1 mm 1.5 in. thick.6
20、.1.3.2 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.6.1.3.3 A 3.17-mm 0.125-in. by 228.6-mm 9-in. diam-eter rubber O-ring is stretched and placed in this groove.6.1.3.4 The t
21、est chamber is seated into the groove on top ofthe O-ring.6.1.4 Tension Rods:6.1.4.1 Equally spaced around the base plate, 158.75 mm6.25 in. from the center of the plate, are six 0.952-mm0.375-in. diameter by 76.2-mm 30-in. long threaded tensionrods.6.1.4.2 Each tension rod is attached to the base p
22、late by twohex nuts, one above the plate, and one beneath.6.1.4.3 On two 180 opposing tension rods place a wing nutthat is used to secure the test chamber to the base plate via thehooks referred to in 6.1.2.2.6.1.5 Double Cup Seal Assembly:6.1.5.1 This is used to evenly distribute the consolidationl
23、oad over the soil in the test chamber. It consists of thefollowing parts:6.1.5.2 Two 254.00-mm 10-in. diameter by 4.76-mm0.3125-in. thick rubber cup seals that are placed back to back.They are sandwiched between two 241.3-mm 9.5-in. diam-eter by 12.7-mm 0.5-in. flat PVC plates.6.1.5.3 A 12.7-mm 0.5-
24、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.6.1.5.4 A removable PVC platform that is attached to thecenter rod after the test chamber is completely assembled. Thisis used to seat the deflection di
25、al or transducer on.6.1.6 Top Plate:6.1.6.1 An identical plate to the base plate, including thegroove for test chamber seating, and holes for tension rods togo through.6.1.6.2 A 3.17-mm 0.125-in. by 228.6-mm 9-in. diam-eter rubber O-ring is stretched and placed in the groove.6.1.6.3 A threaded 6.35-
26、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 applied through this air line.6.1.6.4 The double cup seal assembly is mounted through ahole in the center of the top plate
27、. The cup seals are placed suchthat they will be inside the test chamber.6.1.6.5 Apressure gauge for reading the applied air pressureis mounted to the top plate such that it reads the pressure insidethe test chamber.6.1.7 Adeflection dial or electronic displacement transducergraduated in 0.0254-mm 0
28、.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 Drain Mount: A flat PVC plate cut to fitthe inside of the test chamber.NOTE 1See Fig. 1 and Fig. 2 for schematic diagrams of t
29、he testapparatus.7. Materials7.1 Project SoilA quantity of in-situ compressible soillarge enough to perform the number of required tests shall beobtained from the project site. This does not have to beundisturbed soil.NOTE 2The quantity of soil needed shall be figured based on fillingthe test chambe
30、r to a height of 381 mm 15 in. at the desired density.7.2 Silicone SprayThe spray is used to lubricate the insidesurface of the test chamber to minimize friction between thesoil and the chamber surface.8. Hazards8.1 There are no known hazards with the materials, or inperforming the test.9. Sampling,
31、 Laboratory Samples, and Test Specimens9.1 Lot SampleAs a lot sample for acceptance testing, takethe number of units as directed in Table 3 in Practice D4354.Consider rolls of the vertical strip drain to be the primarysampling units.9.2 Laboratory SampleTake for the laboratory sample asample 1829 mm
32、 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 material.9.3 Test SpecimensFrom each laboratory sample cut threetest specimens, each 508.0 mm 20 in. long, making sure eachend of the sp
33、ecimen 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 bolts 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 f
34、rom 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 multiplying 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
35、 soil from 10.1,determine and record the initial moisture content of the soil tobe placed in the test chamber using Eq 1:wi5 WT2 WS!/W# 3100 % (1)where:wi= Initial Moisture Content (%)WT= Total Wet Mass of Soil (g)WS= Dry Mass of Soil (g)D7498/D7498M 09 (2014)1310.3 Secure the test chamber to the bo
36、ttom 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. This isthe height to which the soil will be placed, and is the initialheight of soil in the test chamber.10.5 Spray
37、 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 Assemble the test specimen to the specimen mountingplate by placing the three pre-cut notches over the assemblybolts and t
38、ightening 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 rodsweight.10.7.1 Leaving the items in 10.6 on the scale, tare the scaleout.NOTE 3If the scale can be locked, lock the pl
39、atform 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 in a vertical position, start placing the soil into thetest chamber. Distribute evenly around the drain using handpressure and
40、 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 test specimen in a vertical position as the chamber isfilled with soil.10.8.1 The moisture content, percent saturation, and
41、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 mass of soil has been placed in the chamber.10.9 Apply another coating of non-stick silicone spray tothe inside exposed test
42、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 test specimen. MakeFIG. 2 Prefricated Vertical Strip Drain MountD7498/D7498M 09 (2014)14sure that wax does not splash on expose
43、d 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 uniform 25.4-mm 1-in. layer of moist silicasand on top of the
44、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 careful not to crimp the test specimen or break the waxseal when b
45、ending 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 the center rod of thecup seal assembly and tension rods on th
46、e 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.10.15 Attach the deflection dial or transducer platform tothe center rod.10.15.1 Attach the deflection dial or transducer to the topplate, being sure that
47、 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 in the off position, adjust theair regulators to read 103.42 kPa 15 psi, or as otherwisespecified, but within the sa
48、fe 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 applied to the test soil.11.4 Take the following timed deflection readings:11.4.1 Day 1: 1,2,5,10,30,45,60,90,120,15
49、0,180,210,240,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 are used, after the firstday, readings every 6 h 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 o
