BS 1377-7:1990

What is BS 1377-7 – soil shear strength tests about?

The shear strength of a soil is indicative of its resistance to erosion. BS 1377-7 discusses methods of testing for Soil for civil engineering purposes.

BS 1377-7 is the seventh part of the multi-series, and describes methods of test for determining shear strength parameters of soils in terms of total stresses, or (in the case of drained direct shear tests) in terms of effective stresses which are equal to total stresses.

Note: The titles of the publications referred to in BS 1377-7 are listed on the inside back cover.

Who is BS 1377-7 – soil shear strength tests for?

BS 1377-7 on soil shear strength tests for civil engineering purposes is useful for:

• The construction industry
• Civil engineers
• Ground engineering consultants
• Construction contractors and clients
• Ground investigation specifiers
• Geotechnical advisers
• Geotechnical soils testing laboratories, managers, and technicians
• Local authority engineers and planners
• Infrastructure managers and planners

Why should you use BS 1377-7 – soil shear strength tests?

Soil shear strength is made up of cohesion between particles and resistance of particles sliding over each other due to friction or interlocking. Shear strength is determined either by measuring the shearing force causing failure (direct shear tests) or by derivation from the measured compressive strength (unconfined or triaxial compression tests).

BS 1377-7 walks you through the test procedure by providing you with details such as apparatus, preparation of specimens, cell assembly, preparation of test specimen, checking and preparation of apparatus, test procedures, calculation, and plotting results for the shear strength of soils.

None of these procedures requires measurement of pore water pressure, which is covered in BS 1377-8.

You could refer to BS 1377-1 for general requirements that are relevant to all parts of BS 1377-7, and to BS 1377-1 and BS 1377-4 for methods of preparation of soil and of test specimens.

Direct shear tests comprise:

• Laboratory vane test procedure, for soft to firm cohesive soils
• Small shear box procedures for determining the angle of shear resistance of cohesionless soils, and the drained peak and residual shear strength parameters of cohesive soils
• Large shear box procedures for determining similar properties of gravelly soils, or on large block samples
• Small ring shear procedure for drained residual shear strength parameters of remoulded clays

Compression tests comprise:

• The unconfined compression test procedure, in the laboratory and in a portable apparatus for use on-site
• Triaxial compression test procedure from which the undrained shear strength is derived
• Triaxial compression test procedure in several stages on one specimen, for deriving undrained shear strength

The unconfined compression test procedure using portable apparatus, and the single-stage triaxial compression test, are similar in principle to those given in the 1975 Standard. All the other procedures are new additions.

BS 1377-7 on the test for soils for civil engineering purposes, increase the efficiency of the project.

BS 1377-7 aids in the protection of a wide range of pores and fissures.

Overall, BS 1377-7 assists you in demonstrating better and more cost-effective soil management strategies for reducing the possibility of foundation issues, and determining the best building options to use.