What is an unconfined compression test?
Unconfined Compression Test (UCT) is a simple laboratory testing method to assess the mechanical properties of rocks and fine-grained soils. It provides a measures of the undrained strength and the stress-strain characteristics of the rock or soil.
Why is unconfined compression test important?
The primary purpose of the Unconfined Compression Test is to quickly determine a measure of the unconfined compressive strength of rocks or fine-grained soils that possess sufficient cohesion to permit testing in the unconfined state.
What is the difference between unconfined compression test and triaxial test?
The main difference between Unconfined compression test and triaxil compression test is that in this test the confining cell pressure is kept zero during the test, in fact it is a special case of triaxial test.
What are the limitations of unconfined compression test?
3) Limitations of the unconfined compressive test i) Sample disturbance ( in case of samples obtained from thin wall tube) ii) Total and/or effective stress conditions in the field are not properly simulated.
Why is UCS important?
Uniaxial compressive strength (UCS) is one of the most important mechanical properties of rocks widely used in different engineering related projects to evaluate the stability of structures against loads.
How do you conduct a UCS test?
Test procedure
- Take two frictionless bearing plates of 75 mm diameter.
- Place the specimen on the base plate of the load frame (sandwiched between the end plates).
- Place a hardened steel ball on the bearing plate.
- Adjust the center line of the specimen such that the proving ring and the steel ball are in the same line.
Why is this test called an unconfined test?
The Unconfined Compression Test is a laboratory test used to derive the Unconfirmed Compressive Strength (UCS) of a rock specimen. Unconfirmed Compressive Strength (UCS) stands for the maximum axial compressive stress that a specimen can bear under zero confining stress.
What is the differences between UC and UU test?
In the UC test, the acquired sample (usually from a Shelby tube) is tested in air (confining pressure of zero), analogous to a concrete cylinder. In the UU test, a membrane is used to create external confining pressure, more applicable to field situations.
What is the difference between confined and unconfined compressive strength?
From the beginning, unconfined condition under compressive load give the low compressive strength and failed due to early crack initation. Confined condition is proposed to give material supporting to prevent brittle collapse and will give more strength.
What does unconfined compressive strength mean?
A measure of a material’s strength. The unconfined compressive strength (UCS) is the maximum axial compressive stress that a right-cylindrical sample of material can withstand under unconfined conditions—the confining stress is zero.
What is a UU test?
Unconfined Compression (UC) Test In UU test, soil specimen is not consolidated and thus drainage is not allowed either during application of cell pressure (confining pressure) or shearing. UU triaxial test is the fastest triaxial test to obtain shear strength parameters (c,Φ) of soil.
What is unconfined compressive strength?
The unconfined compressive strength (UCS) is the maximum axial compressive stress that a right-cylindrical sample of material can withstand under unconfined conditions—the confining stress is zero.
The unconfined compression test is used to determine the unconfined compressive strength of a rock specimen and an unconfined compression test is a laboratory test.
What is unconfirmed compressive strength under zero confining stress?
Under zero confining stress, unconfirmed compressive strength stands for the maximum axial compressive stress specimen can bear and due to this stress is applied along the longitudinal axis. In geotechnical design, unconfirmed compressive strength (UCS) is a parameter which is widely used but the strength in-situ may not be represented.
How to obtain the unconfined compressive strength from calibrated charts?
A field apparatus is also available to obtain the unconfined compressive strength from calibrated charts. The apparatus is shown diagrammatically in below figure. The strain-controlled unconfined compression test is used universally.
What is unconfined compressive strength of clay?
The value from which the unconsolidated shear strength of the clay under unconfined conditions is calculated is determined by the unconfined compressive strength and the unconfined compression test is used for the determination of this unconfined compressive strength.