ASTM D2166 – 00 Standard Test Method for Unconfined Compressive Strength of Cohesive Soil

ASTM D2166 – 00 Phương pháp thí nghiệm nén 1 trục có nở hông QU

 

1. Scope

1.1 This test method covers the determination of the unconfined compressive strength of cohesive soil in the undisturbed, remolded, or compacted condition, using strain-controlled application of the axial load.

1.2 This test method provides an approximate value of the strength of cohesive soils in terms of total stresses.

1.3 This test method is applicable only to cohesive materials which will not expel or bleed water (water expelled from the soil due to deformation or compaction) during the loading portion of the test and which will retain intrinsic strength after removal of confining pressures, such as clays or cemented soils. Dry and crumbly soils, fissured or varved materials, silts, peats, and sands cannot be tested with this method to obtain valid unconfined compression strength values.

ASTM D2166 – 00 Standard Test Method for Unconfined Compressive Strength of Cohesive Soil
ASTM D2166 – 00 Phương pháp thí nghiệm nén 1 trục có nở hông QU

2. Referenced Documents

ASTM Standards:

D 422 Test Method for Particle-Size Analysis of Soils2

D 653 Terminology Relating to Soil, Rock, and Contained Fluids2

D 854 Test Method for Specific Gravity of Soil Solids by Water Pycnometer2

D 1587 Practice for Thin-Walled Tube Sampling of Soils for Geotechnical Purposes2

D 2216 Test Method for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass2

D 2487 Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System)2

D 2488 Practice for Description and Identification of Soils (Visual-Manual Procedure)2

D 2850 Test Method for Unconsolidated, Undrained Compressive Strength of Cohesive Soils in Triaxial Compression

 

3. Terminology

3.1 Definitions: Refer to Terminology D 653 for standard definitions of terms.

3.2 Definitions of Terms Specific to This Standard:

3.2.1 unconfined compressive strength (qu)—the compressive stress at which an unconfined cylindrical specimen of soil

3.2.2 shear strength (su)—for unconfined compressive strength test specimens

4. Significance and Use

4.1 The primary purpose of the unconfined compression test

4.2 Samples of soils having slickensided or fissured structure

4.3 If both an undisturbed and a remolded test are performed on the same sample, the sensitivity of the material can

be determined.

ASTM D2166  Standard Test Method for Unconfined Compressive Strength of Cohesive Soil
ASTM D2166  Phương pháp thí nghiệm nén 1 trục có nở hông QU

5. Apparatus

5.1 Compression Device

5.2 Sample Extruder

5.3 Deformation Indicator

5.4 Dial Comparator

5.5 Timer

5.6 Balance

ASTM D2166  Standard Test Method for Unconfined Compressive Strength of Cohesive Soil
ASTM D2166  Phương pháp thí nghiệm nén 1 trục có nở hông QU

6. Preparation of Test Specimens

6.1 Specimen Size

6.2 Undisturbed Specimens

6.3 Remolded Specimens

6.4 Compacted Specimens

 

7. Procedure

7.1 Place the specimen in the loading device so that it is centered on the bottom platen.

7.2 Make a sketch, or take a photo, of the test specimen at failure showing the slope angle of the failure surface.

7.3 A copy of a example data sheet is included in Appendix

ASTM D2166  Standard Test Method for Unconfined Compressive Strength of Cohesive Soil
ASTM D2166  Phương pháp thí nghiệm nén 1 trục có nở hông QU

8. Calculation

8.1 Calculate the axial strain

8.2 Calculate the average cross-sectional area

8.3 Calculate the compressive stress

8.4 Graph

8.5 If the undisturbed and remolded compressive strengths are remolded, determine the sensitivity

ASTM D2166 – 00 Standard Test Method for Unconfined Compressive Strength of Cohesive Soil

9. Report

9.1 The report should include the following:

9.1.1 Identification and visual description of the specimen,

9.1.2 Initial dry density and water content,

9.1.3 Degree of saturation (Note 8), if computed,

9.1.4 Unconfined compressive strength and shear strength,

9.1.5 Average height and diameter of specimen,

9.1.6 Height-to-diameter ratio,

9.1.7 Average rate of strain to failure, %,

9.1.8 Strain at failure, %,

9.1.9 Liquid and plastic limits, if determined,

9.1.10 Failure sketch or photo,

9.1.11 Stress-strain graph, if prepared,

9.1.12 Sensitivity, if determined,

9.1.13 Particle size analysis, if determined,

9.1.14 Remarks

ASTM D2166 – 00 Phương pháp thí nghiệm nén 1 trục có nở hông QU

10. Precision and Bias

10.1 Precision

10.2 Bias

 

11. Keywords

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

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