BS 1377-7:1990 PDF Download

The BS 1377-7:1990 standard provides guidelines for determining the shear strength parameters of soils in terms of total stresses or effective stresses. The standard does not require the measurement of pore water pressure, which is covered in a different part of the BS 1377 series.

The standard includes various tests for determining shear strength. The direct shear tests involve measuring the shearing force causing failure and can be conducted using the laboratory vane test procedure for soft to firm cohesive soils. For cohesionless soils and cohesive soils, small shearbox procedures can be used to determine the angle of shear resistance and the drained peak and residual shear strength parameters. Large shearbox procedures are suitable for determining similar properties of gravelly soils or large block samples. The small ring shear procedure is used for determining drained residual shear strength parameters of remoulded clays.

Compression tests are another method for determining shear strength. The unconfined compression test procedure can be conducted both in the laboratory and on-site using a portable apparatus. The triaxial compression test can be used to derive undrained shear strength, and the multiple-stage triaxial compression test is used for the same purpose but with several stages on one specimen.

Some of the procedures described in the standard, such as the unconfined compression test with a portable apparatus and the single-stage triaxial compression test, are similar to those provided in the 1975 standard, while the remaining procedures are new additions.