ASTM D6598-2011 4375 Standard Guide for Installing and Operating Settlement Platforms for Monitoring Vertical Deformations《监测垂直变形用沉降平台的安装和操作标准指南》.pdf

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1、Designation: D6598 11Standard Guide forInstalling and Operating Settlement Platforms for MonitoringVertical Deformations1This standard is issued under the fixed designation D6598; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the

2、 year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () 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 re

3、ading ofsettlement platform to determine the magnitude and rate offoundation, fill settlements, or both generally under a fill orembankment load. Two types of settlement platforms aredescribed those being monitored by elevation surveys froman external bench mark and those that include an internalref

4、erence system supported on unyielding soil or rock beneaththe compressible layer(s) of interest.1.2 UnitsThe values stated in SI units are to be regardedas standard. No other units of measurement are included in thisstandard.1.3 This guide does not purport to address all of the safetyconcerns, if an

5、y, associated with its use. It is the responsibilityof the user of this guide to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.1.4 This guide offers an organized collection of informationor a series of options and does not reco

6、mmend a specificcourse of action. This document cannot replace education orexperience and should be used in conjunction with professionaljudgement. 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 w

7、hich theadequacy of a given professional service must be judged, norshould this document be applied without consideration of aprojects 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

8、Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and ContainedFluidsD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD5092 Practice for Design and Installation of Ground WaterMo

9、nitoring Wells3. Terminology3.1 Definitions:3.1.1 For definitions of terms in this standard, refer toTerminology D653.3.2 Definitions of Terms Specific to This Standard:3.2.1 settlement platforma system consisting of a squarebase platform with an extendible riser pipe of known lengthwhich is used to

10、 monitor vertical deformations at the elevationof the base platform by survey measurements made of the topof the riser pipe.3.2.2 external and internal reference point systemwith anexternal system, the amount of settlement is determined byreferencing the elevation of the settlement platform to anout

11、side 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 attached to the baseplatform and the inner riser pipe being fixed to an unyieldingstratu

12、m.3.2.3 anchoran anchor system that provides an internalfixed reference point below the base of the settlement platformsystem.3.2.4 extendible risera metal shaft or pipe which can beincrementally lengthened using sections of the same materialand appropriate couplings as fill is placed and compacted

13、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.3.2.5 isolation casinga casing of a larger diameter thanthe extendible risers is used in some installa

14、tions 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.1This guide is under the jurisdiction ofASTM Committee D18 on Soil and Rockand is the direct resp

15、onsibility of Subcommittee D18.23 on Field Instrumentation.Current edition approved Nov. 1, 2011. Published January 2012. Originallyapproved in 2000. Last previous edition approved in 2007 as D659807. DOI:10.1520/D6598-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontac

16、t 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 section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West C

17、onshohocken, PA 19428-2959, United States.3.2.6 For definitions of other terms used in this guide seeTerminology D653.4. Summary of Standard Guide4.1 The standard guide presents recommended designs forsettlement platforms along with procedures to install, operateand monitor them. The standard guide

18、focuses on methods thatpermit (i) the effect of fill placement on underlying strata and(ii) the determination of the relative deformation within a fill.The guide addresses ways in which the instrument is protectedfrom downdrag effects from the fill soils as well as measures toprotect the instrument

19、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. Significance and Use5.1 Earthen fills are often constructed as engin

20、eered 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 throughout the embankment.Temporary embankments or surcharge fills are co

21、nstructed 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 document the magnitudeand rate of settlement, to evaluate the pote

22、ntial 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 provides an accessiblesurvey point that settles with a selected soil

23、 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 volume changes caused bymoisture gain or loss.5.2 Various settlement

24、 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 is not meant to restrict the use ofother equally appropriate desi

25、gns 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-tained in this guide, the precision of this guide is dependent on

26、 thecompetence of the personnel performing it and the suitability of theequipment and facilities used. Agencies that meet the criteria of PracticeD3740 are generally considered capable of competent and objectivetesting. Users of this guide are cautioned that compliance with PracticeD3740 does not it

27、self ensure reliable testing. Reliable testing depends onmany factors; Practice D3740 provides a means of evaluating some ofthese factors.6. Materials6.1 A variety of materials are used in combination toprovide a cost-effective, modular system. Given that theanticipated operational life of settlemen

28、t 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 material selection decisions. The entiresettlement platform system consists

29、 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 regarding materials for each of thesecomponents are provided below.

30、TABLE 1 Suitability and Use of Various Platform ConfigurationsConfigurationFillDeformationsFoundationDeformationsExternalReferenceInternalReferenceFig. 1 NoAYes Yes NoFig. 2 NoAYes NoBYesFig. 3 NoAYes NoBYesAFill settlements could be determined with this configuration if base platformplaced at highe

31、r 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 deformation is required. In some cases, asteel platform 5 to 15 mm thick is

32、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 can be used for thebase platform. In all cases, the thickness of the

33、 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 metal pipe, typically 25 to 50 mm indiameter, is used to reflect the ver

34、tical 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 survey program is complete, some, if not allthe riser pipe can be re

35、covered 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 external pipe is some-times used to isolate the riser pipe from the

36、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 only to isolate the riser pipefrom these surrounding effects and doe

37、s 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 typically only required if the fill orembankment height is greater t

38、han about6mortheplate is toD6598 112be 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-forms that remain in place following completion of construc-

39、tion, installation of a surface protection monument to protectthe riser pipe from tampering is advisable. Design of aprotective casing system as described in Practice D5092 isrecommended.6.6 For installations where an internal reference or bench-mark supported on unyielding soil or rock beneath the

40、com-pressible layer(s) of interest is used, rigid metal pipe similar toFIG. 1 Typical Installation for Externally Referenced Settlement PlatformD6598 113that described in 6.3 above is recommended. Alternatively, ananchor is used in conjunction with metal pipe to ensure a fixedbase reference point. A

41、 typical anchor 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

42、 for which the settlement platform isto be used and whether an external or internal reference pointor bench mark is to be used. This standard test methoddescribes a number of settlement platform systems intended toreflect these alternative configurations as well as a number ofother features such as

43、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 the base platform is preceded by the placement of a beddinglayer. T

44、ypically, a free-draining clean sand is used (see Fig. 1FIG. 2 Typical Installation for Internally Referenced Settlement Platform with Grouted PipeD6598 114for example). If that an external reference point is used, the firstsection of riser pipe is connected to the base platform and theplatform is p

45、ositioned on the bedding sand and 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 levelo

46、f compaction required should be established 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 theplacement of any fill layers with earth-moving

47、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 centimeters, accuracy islimited by the practicality of making the measuremen

48、ts. Asfilling progresses, additional sections of riser pipe are added toFIG. 3 Typical Installation for Internally Referenced Settlement Platform with Borros AnchorD6598 115maintain the top of the riser pipe above the elevation of the fill.Sections of riser pipe between 1 and 2 m long are convenient

49、for assembly as well as monitoring 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 above 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. Aprincipal difference between these systems and the externallyreferenc