Geotechnical

Uncertainties involved in Plate Load Test

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Even though plate load tests are very commonly used, they do not represent the behavior of prototype foundations totally for the following reasons: The zone of influence for prototype foundation is larger and deeper than for small size plate. Thus, in stratified soil deposits the soils at greater depths will have a significant influence on … Read more

9 PRECAUTIONS TO TAKE WHILE PERFORMING STANDARD PENETRATION TEST (SPT)

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There are many pitfalls associated with the standard penetration test. If these are not carefully avoided, the N-values collected from SPT are mere numbers rather than being useful indicators of soil parameters. Some of the precautions to be taken are: Results of standard penetration test are not reproducible in cohesion less soil below water level … Read more

SLAKE DURABILITY TEST OF ROCK SAMPLE (IS-10050-1981)

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Reference IS-10050-1981-Method for determination of slake durability index of rocks. Objective This test is done to find out the resistance offered by a rock sample to weakening and disintegration when subjected to two standard cycles of drying and wetting in a slaking fluid usually water. Apparatus used NAME OF EQUIPMENT CAPACITY LEAST COUNT/ACCURACY Balance As … Read more

DETERMINATION OF WATER CONTENT OF ROCK SAMPLE (IS-13030-1991)

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Reference IS-13030-1991- Method of test for laboratory determination of water content, porosity, density and related properties of rock material. Objective Determination of mass of water contained in a rock sample. Apparatus used Name of equipment Capacity Least count/Accuracy Oven 105±30C 10C Balance As per requirement 0.01% of the sample   Procedure Clean the container and … Read more

UNCONFINED COMPRESSIVE STRENGTH OF ROCK SAMPLE (IS-9143-1979)

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Reference IS-9143-1979-Method for the determination of unconfined compressive strength of rock materials Objective The objective of this test is to determine unconfined compressive strength of rock. This test is primarily done to classify the rock on the basis of strength. Apparatus used Name of equipment Capacity Least count/Accuracy Loading Machine 5000 kN 2.5 N Vernier … Read more

CORRECTION APPLIED TO SPT VALUE

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The N-value observed during testing is not utilized directly in assessing soil properties. These values are corrected to account for The overburden pressure Dilatancy in saturated fine sands and silts Correction for overburden pressure The penetration resistance of soil depends on the over burden pressure. At deeper depth in-situ soil will have higher overburden pressure … Read more

STANDARD PENETRATION TEST (SPT) – THEORY

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This test involves the measurement of the resistance to penetration of a sampling spoon under dynamic loading The resistance is empirically correlated with some of the engineering properties of soil such as density index, consistency, angle of internal friction, bearing capacity etc. This test is useful for general exploration of erratic soil profile for finding … Read more

Geotechnical Engineering

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Overview In a broad sense, geotechnical engineering is that branch of civil engineering that employs scientific methods to determine, evaluate, and apply the interrelationship between the geologic environment and engineered works. In a practical context, geotechnical engineering encompasses evaluation, design, and construction involving earth materials.