Standard Test Method for Unconfined Compressive Strength of Cohesive Soil

Importancia y uso:

5.1 The primary purpose of the unconfined compression test is to quickly measure the compressive strength for those soils that possess sufficient cohesion to permit testing in the unconfined state. The test is performed on non-free draining soils at a strain rate sufficiently high enough such that the soil does not expel water during loading. The degree of saturation of the test specimen can affect drainage conditions during shearing, which may affect the test results.

5.2 Since testing is performed on an unconfined specimen, this test method does not attempt to replicate an in situ state of stress prior to loading. Further, drainage conditions during shearing are not certain. Therefore, this test method provides an index of undrained shear strength.

5.3 Samples of soils having slickensided or fissured structure, samples of some types of loess, very soft clays, dry and crumbly soils and varved materials, or samples containing significant portions of silt or sand, or both (all of which usually exhibit cohesive properties), frequently display higher shear strengths when tested in accordance with Test Method D2850. Also, unsaturated soils will usually exhibit different shear strengths when tested in accordance with Test Method D2850.

5.4 If tests on the same sample in both its intact and remolded states are performed, the sensitivity of the material can be determined. This method of determining sensitivity is suitable only for soils that can retain a stable specimen shape in the remolded state.

Note 2: For soils that will not retain a stable shape Test Method D4648/D4648M or Test Method D2850 may be used to determine sensitivity.

Note 3: The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing/sampling/inspection. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some, but not all, of those factors.

Subcomité:

D18.05

Referida por:

D4219-22, D0653-24A, D4767-11R20, D2850-24, D4832_D4832M-23, D4015-21, D5102_D5102M-24, D2573_D2573M-18

Volúmen:

04.08

Número ICS:

93.020 (Earth works. Excavations. Foundation construction. Underground works)

Palabras clave:

cohesive soil; compressive strength; sensitivity; strain-controlled loading; strength; stress-strain relationships; unconfined compression; undrained shear strength;