Contents
What is meant by Preconsolidation pressure?
Preconsolidation pressure is the maximum effective vertical overburden stress that a particular soil sample has sustained in the past. This quantity is important in geotechnical engineering, particularly for finding the expected settlement of foundations and embankments.
What is Preconsolidation pressure How is it determined?
In 1936, Casagrande proposed the classical method to determine preconsolidation stress using an empirical construction from the e − log σ curve, where e is the void ratio and σ is the vertical effective stress. The effective pressure corresponding to point T is expressed as preconsolidation pressure (σc).
Who founded the method of determination of Preconsolidation pressure Mcq?
14. Who founded the method of determination of pre-consolidation pressure? Explanation: Casagrande in 1936 gave the empirical method for finding the per-consolidation pressure. He selected a point in the graph that has the minimum radius and drew tangents to it.
How can the pre-consolidation pressure on clay be estimated?
The preconsolidation stress represents the maximum vertical effective overburden stress that the soil has experienced, and is used to define the stress history of the soil by means of the overconsolidation ratio OCR ( = σ’p/σ’v, where σ’v is the present vertical effective stress).
What is Casagrande method?
A method for determining the liquid limit of a soil. A paste of soil and water is put in a shallow cup, the paste is cut into two parts with a deep groove and the cup is then dropped repeatedly in a standard manner until the groove has closed owing to the flow of the paste.
Why is the Oedometer test performed?
An oedometer test is a kind of geotechnical investigation performed in geotechnical engineering that measures a soil’s consolidation properties. The results from these tests are used to predict how a soil in the field will deform in response to a change in effective stress.
What is Atterberg limit of soil?
The Atterberg limits consist of the following key values of moisture content: The Liquid Limit (LL) is the moisture content at which a fine-grained soil no longer flows like a liquid. The Plastic Limit (PL) is the moisture content at which a fine-grained soil can no longer be remolded without cracking.
How do you determine whether the clay is normally consolidated?
A clay soil is said to be normally consolidated if the effective overburden pressure that it is currently experiencing is the maximum it has ever experienced in its history.
How do I find my primary consolidation settlement?
The primary consolidation settlement can be calculated from the coefficient of volume compressibility mv, which can further lead to the Young’s modulus E′ = (1 + v′)(1 − 2v′)/[mv(1 − v′)], with an assumed Poisson’s ratio v′.
Which method of water content is most accurate?
Oven dry method
Oven dry method is the most accurate and simplest method for water content determination. In this method complete drying of soil sample occur and water content in sample is calculated accurately by a maintained temperature in the oven ( 105° C to 110° C) for 24 hours.
How liquid limit is determined?
Liquid limit is the water content where the soil starts to behave as a liquid. Liquid limit is measured by placing a clay sample in a standard cup and making a separation (groove) using a spatula. The cup is dropped till the separation vanishes. The water content of the soil is obtained from this sample.
What are the three stages of consolidation?
The consolidation of soil is divided into three stages including initial consolidation, primary consolidation, and secondary consolidation. The consolidation of soil is time-dependent and its analysis is usually based on Terzaghi’s theory.