1、BRITISH STANDARD BS 7334-3: 1990 ISO 8322-3: 1989 Incorporating Amendment No. 1 Measuring instruments for building construction Part 3: Methods for determining accuracy in use: Optical levelling instrumentsBS7334-3:1990 This British Standard, having been prepared under the directionof the Basic Data
2、 andPerformance Criteria forCivilEngineering and BuildingStructures StandardsPolicy Committee,waspublished underthe authority of the BoardofBSI and comes intoeffecton 30September1990 BSI 07-1999 The following BSI references relate to the work on this standard: Committee reference BDB/4 Draft for com
3、ment 87/10028 DC ISBN 0 580 18697 0 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Basic Data and Performance Criteria for Civil Engineering and Building Structures Standards Policy Committee (BDB/-) to Technical Committee BDB/4, upon w
4、hich the following bodies were represented: Association of County Councils British Standards Society Building Employers Confederation Chartered Institution of Building Services Engineers Concrete Society Department of Education and Science Department of the Environment (Building Research Establishme
5、nt) Department of the Environment (Property Services Agency) Incorporated Association of Architects and Surveyors Institute of Building Control Institute of Clerks of Works of Great Britain Inc. Institution of Civil Engineers Institution of Structural Engineers Institution of Water and Environmental
6、 Management Royal Institute of British Architects Royal Institution of Chartered Surveyors The following body was also represented in the drafting of the standard, through subcommittees and panels: Chartered Institute of Building Amendments issued since publication Amd. No. Date Comments 9319 Novemb
7、er 1996 Indicated by a sideline in the marginBS7334-3:1990 BSI 07-1999 i Contents Page Committees responsible Inside front cover National foreword ii 0 Introduction 1 1 Scope 1 2 Field of application 1 3 References 1 4 General 1 5 Procedures for optical levelling instruments 2 Figure 1 Flow diagram
8、for accuracy in use tests 3 Figure 2 Selection of levelling points 7 Table 1a Field observations and calculations: example 5 Table 1b Field observations and calculations: data sheet 6 Table 2a Field observations and calculation: example 9 Table 2b Field observations and calculations: data sheet 10 P
9、ublications referred to Inside back coverBS7334-3:1990 ii BSI 07-1999 National foreword This Part of BS7334 has been prepared under the direction of the Basic Data and Performance Criteria for Civil Engineering and Building Structures Standards Policy Committee. It is identical with ISO8322-3:1989 “
10、Building construction Measuring instruments Procedures for determining accuracy in use Part 3: Optical levelling instruments” published by the International Organization for Standardization (ISO); and gives the testing procedures to be adopted for optical levelling instruments. The series of Parts c
11、omprising BS7334 will assist in ascertaining whether particular measuring equipment is appropriate to intended measuring tasks; they are also intended for assessing the accuracy in use of measuring instruments in general use on construction sites. Part 1:1990 Theory; Part 2:1990 Measuring tapes; Par
12、t 3:1990 Optical levelling instruments; Part 4:1992 Theodolites; Part 5:1992 Optical plumbing instruments; Part 6:1992 Laser instruments; Part 7:1992 Instruments when used for setting out; Part 8:1992 Electronic distance-measuring instruments up to150m. The Parts are referred to in BS5606:1990 “Guid
13、e to accuracy in building”. Cross-references International standard Corresponding British Standard BS ISO 3534 Statistics, vocabulary and symbols ISO 3534-1:1993 BS ISO 3534-1:1993 Probability and general statistical terms (Identical) ISO 3534-3:1985 BS ISO 3534-3:1985 Glossary of terms relating to
14、the design of experiments (Identical) BS 5964 Building setting out and measurement ISO 4463-1:1989 Part 1:1990 Methods of measuring, planning and organization and acceptance criteria (Identical) ISO 4463-2:1995 Part 2:1996 Measuring stations and targets (Identical) ISO 4463-3:1995 Part 3:1996 Check-
15、lists for the procurement of surveys and measurement services (Identical) ISO 7078:1985 BS 6953:1988 Glossary of terms for procedures for setting out, measurement and surveying in building construction (including guidance notes) (Identical)BS7334-3:1990 BSI 07-1999 iii The Technical Committee has re
16、viewed the provisions of ISO7077, to which reference is made in the text, and has decided that they are acceptable for use in conjunction with this standard. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for thei
17、r correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, pages1 to 10, an inside back cover and a back cover. This standard has been updated (see
18、copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on theinside front cover.iv blankBS7334-3:1990 BSI 07-1999 1 0 Introduction This International Standard consists of a series of parts specifying test procedures to be adopted when determining and
19、assessing the accuracy in use of measuring instruments in building construction. The first part gives the theory; subsequent parts give the procedures for determining the accuracy in use of measuring instruments for measurements. The complete series will consist of the following parts: Part 1: Theor
20、y; Part 2: Measuring tapes; Part 3: Optical levelling instruments; Part 4: Theodolites; Part 5: Optical plumbing instruments; Part 6: Laser instruments; Part 7: Instruments when used for setting out; Part 8: Electronic distance-measuring instruments. Other International Standards for testing measuri
21、ng instruments for land surveying purposes, and for measuring procedures in ordnance survey, are in preparation. 1 Scope This part of ISO8322 specifies test procedures to be adopted when determining and assessing the accuracy in use of optical levelling instruments for measurement purposes. 2 Field
22、of application The procedures given in this part of ISO8322 apply when these optical levelling instruments are used in building construction for surveying, check and compliance measurements, and also when obtaining accuracy data. 3 References ISO 3534, Statistics Vocabulary and symbols. ISO 4463-1,
23、Measurement methods for building Setting-out and measurement Part 1: Planning and organization measuring procedures, acceptance criteria. ISO 7077, Measuring methods for building General principles and procedures for the verification of dimensional compliance. ISO 7078, Building construction Procedu
24、res for setting out measurement and surveying Vocabulary and guidance notes. ISO 8322-1, Building construction Measuring instruments Procedures for determining accuracy in usePart 1: Theory. 4 General 4.1 Before commencing surveying, check and compliance measurements, when obtaining accuracy data or
25、 setting out, it is important that the operator investigates that the accuracy in use of the measuring equipment is appropriate to the intended measuring task. This International Standard recommends that the operator carries out test measurements under field conditions to establish the accuracy achi
26、eved when he uses a particular measuring instrument and its ancillary equipment. To ensure that the assessment takes account of various environmental influences, two series of measurements need to be carried out under different conditions. The particular conditions to be taken into account may vary
27、depending on where the tasks are to be undertaken. These conditions will include variations in air temperature, wind speed, cloud cover and visibility. Note should also be made of the actual weather conditions at the time of measurement and the type of surface over which the measurements are made. T
28、he sets of conditions chosen for the tests should match those expected when the intended measuring task is actually carried out. See ISO7077 and ISO7078.BS7334-3:1990 2 BSI 07-1999 The procedures are designed so that the systematic errors are largely eliminated and assume that the particular instrum
29、ents are in known and acceptable states of user adjustment according to methods detailed in the manufacturers handbooks. Accuracy in use procedures require tests to be made with the same instrumentation and the same observer, within a short interval of time. These are “repeatability conditions” as d
30、efined in ISO3534. The accuracy in use is expressed in terms of the standard deviation. 4.2 Figure 1 indicates schematically the decisions to be made when establishing that the accuracy associated with a given surveying method and particular measuring equipment is appropriate to the intended measuri
31、ng task. In particular, the decisions apply when adopted by a particular operator under a range of environmental conditions which are likely to occur when the task is actually carried out. Where the contract documentation specifies the required tolerance for the intended measuring task, it is recomm
32、ended that this tolerance, which is normally given in terms of the permitted deviation P (P =2,5 ) of the measuring task, is compared with the accuracy in use data obtained either from previous accuracy in use tests or from general data A which indicate the expected accuracy in use of given measurin
33、g equipment. On those occasions that the previously obtained data indicates that the accuracy in use associated with the given measuring equipment exceeds the specified permitted deviation of the measuring task, consideration should be given to either selecting a different method and/or a more preci
34、se instrument, or discussing with the designer the need for such a small permitted deviation. SeeISO4463-1. Before obtaining an overall estimate of the accuracy in use, it is recommended that each standard deviation for a given series of measurements undertaken under particular environmental conditi
35、ons is compared, as indicated inFigure 1, with the specified permitted deviation. Where the comparison shows that the specified permitted deviation has not been achieved for one series of measurements, an additional series of measurements should be carried out under as near as possible similar envir
36、onmental conditions to those which applied in that original series of measurements. 5 Procedures for optical levelling instruments 5.1 General The normal practice is for measuring accuracy to be referred to 1km of double levelling. However, the operating distance in building construction will not no
37、rmally exceed40m. Therefore this part of ISO8322 recommends that the accuracy in use is presented in terms of a standard deviation for a distance of1km (method1) or for a distance of40m (method2). Each presentation should be in terms of double levelling. The operator shall choose the method most rel
38、evant to this requirement. The following test procedures should be adopted for determining the accuracy in use by a particular survey team with a particular instrument and its ancillary equipment. 5.2 Method 1 5.2.1 Observation procedure (see Table 1) 5.2.1.1 Establish two levelling points approxima
39、tely 250m apart. The points shall be reliably defined for the duration of the test measurements. 5.2.1.2 Each of the two series of measurements on separate days shall consist of five double levellings: the forward and reverse levelling are considered to be measurements independent of each other. Whe
40、n establishing the accuracy in use for very accurate levels (sometimes incorrectly called “precision levels”: seeISO7078 regarding the difference between “accuracy” and “precision”), sighting distance should be approximately20m; otherwise the sighting distance should be about 40m. All measurements s
41、hould be taken to the nearest millimetre or to the nearest0,1mm when using a level fitted with a parallel plate micrometer. 5.2.1.3 The ancillary equipment used and the environmental conditions shall be similar to those expected in the intended actual measurement. 5.2.1.4 Record the environmental co
42、nditions. Changes of environmental conditions during the construction period may render the test result inapplicable. In such a case the test should be repeated under the new conditions.BS7334-3:1990 BSI 07-1999 3 Assumptions: P is the permitted deviation of the measuring task A is the accuracy in u
43、se, generally expressed as deviation A; (both P and A are considered to include the dimensional variability associated with 2,5 times the standard deviation ) s are the deviations obtained in the field tests Figure 1 Flow diagram for accuracy in use testsBS7334-3:1990 4 BSI 07-1999 5.2.2 Calculation
44、 procedure (see Table 1) A complete example of the analysis is given in Table 1 (columns3,4and5) for an engineers level and it is recommended that this form of presentation be generally adopted. All calculations are in terms of the value of the differences of level between the two stabilized level p
45、oints. 5.2.2.1 Calculate the arithmetic mean (column3). For example: 318,5 5.2.2.2 Calculate the deviations v of each value from arithmetic mean (column4). For example: level2 reverse: 1,5mm To minimize the effect of rounding errors, the calculation of each deviation v should be carried out to the n
46、earest0,1mm if the values are in millimetres and to the nearest0,01mm if the values are in0,1mm. As an arithmetic check the sum of the ten deviations should be zero. 5.2.2.3 Calculate the squares v 2of all values in column4 and the sum of the squares. 5.2.2.4 Calculate the standard deviation s 1of a
47、 difference in level for a line of250m length on the first day as the square root of the sum of squares divided by9 (= number of redundant observations).5.2.2.5 Calculate the standard deviation s 1(km)of a difference in level for a line of1km as the standard deviation of the line of250m length multi
48、plied by the square root of4.5.2.2.6 Calculate the standard deviation of a difference in double levelling for a line of1km as the standard deviation of a1km levelling line divided by the square root of2.5.2.2.7 Repeat procedures5.2.1.2 to5.2.2.6 on a second day to obtain s 2 . 5.2.2.8 The overall st
49、andard deviation to be expected of any1km double levelling is For example s (km double level) =6mm For example: level 2 reverse: 2,25 mm 2 the sum of the squares: 94,50 mm 2 For example: For example: For example: xBS7334-3:1990 BSI 07-1999 5 Table 1a) Field observations and calculations: example Measurement Difference in level Mean v v 2 mm mm mm mm 2 1 2 3 4 5 1 Forward Reverse 320 315 + 1,5 3,5 2,25 12,25 2 Forward Reverse 324 317 + 5,5 1,5 30,25 2,25 3 Forward Reverse 319 319 + 0
