TIME IS running out for the UK geotechnical community to have its say on the geotechnical Eurocode, warns John Powell, associate director of the BRE Centre for Ground Engineering.
Imminent conversion of Eurocode 7:
Geotechnical design to full Euronorm status means practitioners' comments are urgently required by the working groups carrying out the conversions, he said.
'It is unlikely that there will be any subsequent opportunity to comment on the Part 2 and 3 documents, so it is imperative that comments are made soon.'
Eurocode 7: Geotechnical design - Part 1 General Rules, was published as an ENV (or trial version) by BSI in 1995 as DD ENV1997-1:1995. It is supplemented by two additional documents, Part 2, Design assisted by laboratory testing, and Part 3, Design assisted by field testing.
Powell is the UK national technical contact for the work of CEN Technical Committee 341, Geotechnical Testing and Sampling which recently began developing European standards on geotechnical investigation and testing designed to complement the design Eurocodes. Five working groups have been formed to cover a variety of testing and more are planned.
Originally it was envisaged the first working groups would produce draft standards this year for submission to the main CEN TC341 committee.
Once accepted they would be translated and then sent to national standards bodies for publication as ENVs - probably taking about a year to reach this stage after acceptance. There would be a rolling programme so documents would be processed as completed by the current and future working groups.
Powell said formation of working groups to convert the ENVs of Parts 2 and 3 of Eurocode 7 into ENs has put pressure on CEN TC341 to accelerate the production of the testing standards so they are available for reference by Parts 2 and 3.The first of these, on dynamic probing and the SPT, will be voted on next month.
'Proposals are being reviewed to further accelerate the production of the standards for those insitu testing devices not covered by a working group and also for laboratory testing; it would seem that documents could appear quite quickly, ' he said.
'The form of the ENs will change from that of the ENVs as a result of this work, ' he added.'Much of Parts 2 and 3 referring to test procedures are likely to be removed. It is probable that the two parts will be combined in the process of conversion to an EN.'
Eurocode 7 Parts 2 and 3 aim to help designers to choose test programme requirements, specification, apparatus, as well as the evaluation and presentation of test results.
'The documents were not intended to comprise full standard testing procedures but to include minimum test requirements; they were not intended to replace BS1377 and BS5930, ' said Powell.
Part 2, Design assisted by laboratory testing, covers common geotechnical laboratory tests, selected on the basis of their importance in practice, their availability in commercial laboratories and the existence of national test procedures that could become widely accepted in Europe. Less commonly used and more advanced tests are only mentioned in sections dealing with related tests.
Part 3, Design assisted by field testing, describes various types of site investigation, including desk studies, preliminary, design and control investigations. It refers to the reporting requirements of Part 1 and for a range of insitu tests. There are also short sections on soil and rock sampling and on groundwater measurements.
Both parts introduce the concept of a derived value, defined as a 'value of a geotechnical parameter obtained by theory, correlation or empiricism from test results' Derived values form the basis for the selection in ENV1997-1 of characteristic values of ground properties.
l Comments on Eurocode 7 Parts 2 and 3 should be sent to David Hyde at the BSI, email:
david. hyde@bsi-global. com Those willing to comment on drafts or become part of a UK mirror group for individual test documents for CEN TC341 should contact John Powell (powellj@ bre. co. uk) or Andrew Charles (charlesa@bre. co. uk).