Standard Test Method for Consolidated Undrained Direct Simple Shear Testing of Fine-Grained Soils

Importancia y uso:

5.1 The shear strength of a specimen depends on the method of shearing, soil type, vertical consolidation stress, time of consolidation, rate of strain, and prior stress history of the soil.

5.2 In this test, the shear strength is measured under constant volume conditions that are equivalent to undrained conditions for a saturated specimen; hence, the test is applicable to field conditions wherein soils have fully consolidated under one set of stresses, and then are subjected to changes in stress without time for further drainage to take place.

5.3 The constant volume (undrained) strength is a function of stress conditions. In this test method, the strength is measured under plane strain conditions and the principle stresses continuously rotate due to the application of shear stress. This simple shear stress condition occurs in many field situations including zones below a long embankment and around axially loaded piles.

5.4 The state of stress within the simple shear specimen is not sufficiently defined nor uniform enough to allow rigorous interpretation of the results. Expressing the data in terms of the shear stress and vertical effective stress on the horizontal plane is useful for engineering purposes, but should not be confused with the effective stress parameters derived from other shear tests having better defined states of stress.

5.5 The data and the rate of consolidation from the consolidation portion of this test are comparable to results obtained using Test Methods D2435/D2435M provided that the more rigorous consolidation procedure of Test Methods D2435/D2435M is followed.

5.5.1 When using wire reinforced membranes the vertical displacements measured from Test Methods D2435/D2435M are somewhat smaller than for the direct simple shear test because the direct simple shear (DSS) specimen's lateral confinement is less rigid.

5.5.2 The estimated preconsolidation pressure is comparable to that from Test Methods D2435/D2435M, provided the specimen is loaded sufficiently into the normally consolidated range.

Subcomité:

D18.05

Referida por:

D8295-19, F3339-20, D8296-19

Volúmen:

04.09

Número ICS:

13.080.20 (Physical properties of soils)

Palabras clave:

clays; cohesive soils; compacted samples; consolidated undrained test; consolidation test; constant volume test; intact samples; recompression; reconstituted samples; samples; shear apparatus; shear strain; shear strength; shear test; simple shear; soils; stress-strain curve; undisturbed samples; undrained shear tests;