BS 1377-2: Clarifying the use of geotechnical soil testing methods

It’s necessary to conduct effective and appropriate site soil investigations before anything is built. But a proliferation of standards in this area had the potential to create confusion over which test methods to apply. For greater clarity, a newly revised British Standard brings together all the commonly used test methods that aren’t covered in the international soil test standards, as this blog post explains.

Before any infrastructure or building project can get underway, civil and ground engineers need to ensure that the subsurface conditions are suitable. They’ll do so by testing soils to determine characteristics such as compaction, permeability, compressibility and erodibility, and to determine shear strength of soils in terms of both total and effective stresses. Which laboratory test methods and classifications to apply for the most efficient and reliable results is the subject of a newly revised British Standard.

Consolidating the 1990 standards

Revision work on the 1990 version of BS 1377-2 was undertaken by geotechnical and geo-environmental specialists with a remit to clarify the appropriate tests.

This was needed because the longstanding series of British Standards in this area – the BS 1377 series – contains geotechnical tests that are now outside the scope of the European and international geotechnical investigation standards committees (CEN/TC 341 and ISO/TC 182 respectively). Yet these tests are still in demand and carried out by UKAS accredited UK laboratories. They are also performed outside of Europe, particularly where there are no equivalent standards.

It therefore seemed important that the standard should be updated to provide the maximum amount of assistance to those who’re navigating which tests to use. The result is BS 1377-2:2022 Methods of test for soils for civil engineering purposes – Part 2: Classification tests and determination of geotechnical properties.

Preventing confusion

BS 1377-2:2022 is the second in a four-part series of British Standards on soil testing for civil engineering. The other parts are now Part 1 on general requirements and sample preparation; Part 3 on chemical and electrotechnical tests and Part 4 on in-situ tests, which will supersede BS 1377-9:1990. The new Part 2 provides test methods for commonly carried out geotechnical soil test methods used in ground engineering.

Incorporating updated references and language, this 2022 standard provides test methods for all the commonly accepted geotechnical soil test methods used in ground engineering, but not included in the international series of standards, BS EN ISO 17892-1 to BS EN ISO 17892-12 on geotechnical investigation and testing.

In addition, the big change is that BS 1377-2:2022 consolidates all the tests that were previously found in BS 1377 parts 2, 4, 5, 6, 7, and 8 into one document. Therefore, the new version includes classification tests (from Part 2); compaction-related tests (from Part 4); compressibility, permeability and durability tests (from Part 5); consolidation and permeability tests in hydraulic cells and with pore pressure measurement (from Part 6); shear strength tests – total strength (from Part 7); and shear strength tests – effective strength (from Part 8).

The revision has also made it possible to withdraw all the overlapping content that was in both the British Standards and the international standards. It’s also provided the opportunity to withdraw a couple of tests for safety reasons: namely the determination for volume shrinkage methods, which used mercury.

Finally, for additional clarification, the revised BS 1377-2:2022 now also includes references and complementary/non-contradictory commentary on the tests in the international series of standards. These are the tests on determining water content, liquid limit, plastic limit, density, particle density and particle size distribution, as well as the incremental loading oedometer test, the unconfined compression test, the unconsolidated undrained triaxial test, the consolidated triaxial compression tests on water saturated soils, the direct shear tests and permeability tests.

The end result is an up-to-date standard that should now eliminate any confusion about which geotechnical soil tests should be carried out.