1、Designation: D 6598 07Standard Guide forInstalling and Operating Settlement Platforms for MonitoringVertical Deformations1This standard is issued under the fixed designation D 6598; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, t
2、he year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This guide provides recommended designs and proce-dures for the fabrication, installation, operation, and
3、 reading ofsettlement platform to determine the magnitude and rate offoundation, fill settlements, or bothgenerally under a fill orembankment load. Two types of settlement platforms aredescribed those be monitored by elevation surveys from anexternal bench mark and those that include an internal ref
4、er-ence system supported on unyielding soil or rock beneath thecompressible layer(s) of interest.1.2 This guide does not purport to address all of the safetyconcerns, if any, associated with its use. It is the responsibilityof the user of this guide to establish appropriate safety andhealth practice
5、s and determine the applicability of regulatorylimitations prior to use.1.3 This guide offers an organized collection of informationor a series of options and does not recommend a specificcourse of action. This document cannot replace education orexperience and should be used in conjunction with pro
6、fessionaljudgement. Not all aspects of this guide may be applicable inall circumstances. This ASTM standard is not intended torepresent or replace the standard of care by which theadequacy of a given professional service must be judged, norshould this document be applied without consideration of apr
7、ojects many unique aspects. The word “standard” in thetitle of this document means only that the document has beenapproved through the ASTM consensus process.2. Referenced Documents2.1 ASTM Standards:2D 653 Terminology Relating to Soil, Rock, and ContainedFluidsD 3740 Practice for Minimum Requiremen
8、ts for AgenciesEngaged in the Testing and/or Inspection of Soil and Rockas Used in Engineering Design and ConstructionD 5092 Practice for Design and Installation of GroundWater Monitoring Wells3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 settlement platforma system consisti
9、ng of a squarebase platform with an extendible riser pipe of known lengthwhich is used to monitor vertical deformations at the elevationof the base platform by survey measurements made of the topof the riser pipe.3.1.2 external and internal reference point systemwith anexternal system, the amount of
10、 settlement is determined byreferencing the elevation of the settlement platform to anoutside elevation benchmark; with an internal system, theamount of settlement is determined by measuring the relativedisplacement of two co-axial riser pipes moving relative toeach other, the outer riser pipe being
11、 attached to the baseplatform and the inner riser pipe being fixed to an unyieldingstratum.3.1.3 anchoran anchor system that provides an internalfixed reference point below the base of the settlement platformsystem.3.1.4 extendible risera metal shaft or pipe which can beincrementally lengthened usin
12、g sections of the same materialand appropriate couplings as fill is placed and compacted toensure that the top of the riser remains above the level of thesurrounding ground surface. Depending on whether an externalor internal reference point is being used, there may be one ortwo risers.3.1.5 isolati
13、on casinga casing of a larger diameter thanthe extendible risers is used in some installations to preventdown-drag of soil on the extendible riser that would otherwisebe in contact with the soil from placing additional load on theplatform and thereby leading to overestimates of deformations.3.1.6 Fo
14、r definitions of other terms used in this guide seeTerminology D 653.4. Summary of Standard Guide4.1 The standard guide presents recommended designs forsettlement platforms along with procedures to install, operateand monitor them. The standard guide focuses on methods thatpermit (i) the effect of f
15、ill placement on underlying strata and1This guide is under the jurisdiction ofASTM Committee D18 on Soil and Rockand is the direct responsibility of Subcommittee D18.23 on Field Instrumentation.Current edition approved May 1, 2007. Published June 2007. Originallyapproved in 2000. Last previous editi
16、on approved in 2000 as D 659800.2For referenced ASTM standards, 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.1*A Summary of Changes sectio
17、n appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.(ii) the determination of the relative deformation within a fill.The guide addresses ways in which the instrument is protectedfrom downdrag effects
18、from the fill soils as well as measures toprotect the instrument from damage by earth moving equip-ment. Standard survey procedures are used to determine themagnitude of deformations. Recommended procedures forreporting the details of an installation and the recordeddeformations are presented.5. Sig
19、nificance and Use5.1 Earthen fills are often constructed as engineered struc-tures, for example, dams, or to support engineered structures,for examples, roads or buildings. The weight of the fill maycompress or deform the supporting soil or rock foundationresulting in settlement of the soil througho
20、ut the embankment.Temporary embankments or surcharge fills are constructed toincrease the strength and/or reduce the compressibility offoundation soils prior to placement of the actual foundation orstructure. The designers often monitor the settlement of theearth structure as a function of time to d
21、ocument the magnitudeand rate of settlement, to evaluate the potential for futuresettlement, or to confirm the effectiveness of the surcharge andthe schedule for its removal. The monitoring is performedusing settlement platforms installed prior to or during theembankment construction. A platform pro
22、vides an accessiblesurvey point that settles with a selected soil horizon within orbelow the embankment. Careful design and installation of thesettlement platform can isolate the survey point from extrane-ous sources of movement such as frost-induced heave, com-pression within the embankment, or vol
23、ume changes caused bymoisture gain or loss.5.2 Various settlement platform designs have been devel-oped by the agencies and practitioners that use them. Thisstandard guide provides designs and procedures that can bereferred to in design guidelines, specifications and reports.5.3 This standard guide
24、is not meant to restrict the use ofother equally appropriate designs and procedures for thefabrication, installation, operation, and reading of settlementplatforms to monitor deformations in earthen deposits duringand after construction.NOTE 1Notwithstanding the statements on precision and bias con-
25、tained in this guide, the precision of this guide is dependent on thecompetence of the personnel performing it and the suitability of theequipment and facilities used. Agencies that meet the criteria of PracticeD 3740 are generally considered capable of competent and objectivetesting. Users of this
26、guide are cautioned that compliance with PracticeD 3740 does not itself ensure reliable testing. Reliable testing depends onmany factors; Practice D 3740 provides a means of evaluating some ofthese factors.6. Materials6.1 A variety of materials are used in combination toprovide a cost-effective, mod
27、ular system. Given that theanticipated operational life of settlement platforms is typicallyrelatively short, concerns about long term durability are gen-erally negligible. Accordingly issues such as componentweight, the ease with which the riser pipe can be extended andcost tend to dominate materia
28、l selection decisions. The entiresettlement platform system consists of 4 or 5 distinct compo-nents depending on the specific design. Typical alternativeconfigurations are shown in Figs. 1-3. Key distinctions be-tween these different configurations are summarized in Table 1.Additional considerations
29、 regarding materials for each of thesecomponents are provided below.TABLE 1 Suitability and Use of Various Platform ConfigurationsConfigurationFillDeformationsFoundationDeformationsExternalReferenceInternalReferenceFig. 1 NoAYes Yes NoFig. 2 NoAYes NoBYesFig. 3 NoAYes NoBYesAFill settlements could b
30、e determined with this configuration if base platformplaced at higher elevation.BExternal reference (control) could be used with these configurations also.6.2 Base Platforma square base platform typically rang-ing between 0.3 to 1.0 m on side is placed at the elevation forwhich the vertical deformat
31、ion is required. In some cases, asteel platform 5 to 15 mm thick is used. Alternatively, aplatform 25 to 50 mm thick fabricated from plywood issometimes used. This may be particularly desirable in shortterm applications where degradation of the wood is not aconcern. Other materials such as concrete
32、can be used for thebase platform. In all cases, the thickness of the base platformshould be selected giving consideration to the area of theplatform to ensure that its rigidity is sufficient to avoid localbending.6.3 Riser Pipea rigid metal shaft or an assembly of a rigidmetal shaft and a rigid meta
33、l pipe, typically 25 to 50 mm indiameter, is used to reflect the vertical deformation of theplatform at the ground surface. As layers of fill are placed, theriser pipes are extended by adding additional sections of pipe.Threaded couplings are typically used. These have the advan-tage that after the
34、survey program is complete, some, if not allthe riser pipe can be recovered before the installation is groutedto seal off any unwanted access for water to the subsurface.Use of PVC or other lightweight pipe materials is not recom-mended for reasons of survivability.6.4 Riser Pipe Isolation Casingan
35、external pipe is some-times used to isolate the riser pipe from the surrounding soil.This is done to prevent the effects of extraneous sources ofmovement such as frost-induced heave, skin-friction due tocompression within the fill itself, or moisture induced volumechanges. Given that this casing is
36、only to isolate the riser pipefrom these surrounding effects and does not constitute part ofthe deformation measuring system, PVC or other lightweightpipe materials are typically recommended. As with the riserpipe, the isolation casing can be extended as layers of fill areadded. Isolation casing is
37、typically only required if the fill orembankment height is greater than about6mortheplate is tobe seated on a thin stiff layer overlying softer material where apunching failure might occur as a result of the down-drag loadapplied to the riser-pipe.6.5 Surface Protection Monumentfor settlement plat-f
38、orms that remain in place following completion of construc-tion, installation of a surface protection monument to protectthe riser pipe from tampering is advisable. Design of aprotective casing system as described in Practice D 5092 isrecommended.D65980726.6 For installations where an internal refer
39、ence or bench-mark supported on unyielding soil or rock beneath the com-pressible layer(s) of interest is used, rigid metal pipe similar tothat described in 6.3 above is recommended. Alternatively, ananchor is used in conjunction with metal pipe to ensure a fixedbase reference point. A typical ancho
40、r may consist of a numberof metal prongs which are driven from an initially retractedposition through slots in the conical drive point of an outermetal pipe using an inner metal riser pipe.7. Procedure7.1 A variety of instrument designs are possible dependingon the specific application for which the
41、 settlement platform isto be used and whether an external or internal reference pointFIG. 1 Typical Installation for Externally Referenced Settlement PlatformD6598073or bench mark is to be used. This standard test methoddescribes a number of settlement platform systems intended toreflect these alter
42、native configurations as well as a number ofother features such as the use of riser pipe isolation casing.7.2 Assuming that either the fill level is at the elevation thatthe base platform is to be installed or an excavation has beenmade to permit the level of interest to be accessed, installationof
43、the base platform is preceded by the placement of a beddinglayer. Typically, a free-draining clean sand is used (see Fig. 1for example). If that an external reference point is used, the firstsection of riser pipe is connected to the base platform and theplatform is positioned on the bedding sand and
44、 leveledmanually. If that an internal reference system is used, the lowerend of the shaft is first embedded in the unyielding soil stratum(see section 7.3). Backfill is then hand placed and compactedon top of the base platform to provide initial stability. The levelof compaction required should be e
45、stablished for the specificproject. Ensure that the riser pipe remains vertical during earlyfilling. The zero reading or initial elevation of the top of thebase plate is determined and recorded at this stage prior to theFIG. 2 Typical Installation for Internally Referenced Settlement Platform with G
46、routed PipeD6598074placement of any fill layers with earth-moving equipment. Useof a measurement system capable of measuring deformationsto an accuracy of 1% of the estimated total deformation isappropriate in most cases. For cases where total deformationsare limited to the order of a few centimeter
47、s, accuracy islimited by the practicality of making the measurements. Asfilling progresses, additional sections of riser pipe are added tomaintain the top of the riser pipe above the elevation of the fill.Sections of riser pipe between 1 and 2 m long are convenientfor assembly as well as monitoring
48、purposes. In cases whereconcerns exist about the influence of extraneous factors asnoted in section 6.4 on the recorded deformations, riser pipeisolation casing are added as appropriate to ensure that the topof the isolation casing remains at least 25 mm below the top ofthe riser pipe and always abo
49、ve the top of the fill (see Fig. 1 forexample).7.3 If an internal reference point is used, then a systemconfiguration such as shown in Figs. 2 and 3 should be used. AFIG. 3 Typical Installation for Internally Referenced Settlement Platform with Borros AnchorD6598075principal difference between these systems and the externallyreferenced system shown in Fig. 1 is the section of shaft oranchor that extends below the elevation of the base platforminto the underlying unyielding layer. While externally refer-enced systems are used to indicate the relative vertical move-ment b
