Shear Strength Characteristics of Compacted Residual Soils

What is it about?

The undrained shear strength is critical in the design of foundations as well as the building of other geotechnical constructions such as pavements, backfill material, and embankments. The undrained shear strength represents conservative values of shear strength parameters and in the majority practical cases the undrained shear strength determines the stability aspects of design. The aim of this paper is to understand the effect of intermediate principal stress on undrained strength parameters in relation to Mohr’s strength theory wherein the effect of intermediate principal stress is not incorporated. The shear strength behavior of compacted soils is analyzed by considering failure states of the sol both from Mohr’s Theory and Critical State Concepts. It is observed that the strength behavior of compacted soils is different from the behavior of normally consolidated soils in the sense that cohesion intercept is noticed on q-p plane as well as on τ-s plane. The shear strength parameters are correlated to each other as also with modified plasticity index to propose a framework for analyzing the strength behavior. The data of six different soil samples are used for proposing the phenomenological model and the data of two other samples is used for the purpose of prediction. According to the results of the investigation, the suggested framework can be used to evaluate the shear strength of compacted residual soils.

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Photo by Ivan Bandura on Unsplash

Photo by Ivan Bandura on Unsplash

Why is it important?

an attempt has been made to find out normalized values of the cohesion intercept with basic index properties. The strength behavior of compacted soils is different from the behavior of normally consolidated soils The shear strength behavior of compacted soils comprise of cohesion intercept and friction coefficient The cohesion intercept may arise from unsaturation leading to formation of capillary menisci imparting additional resistance and due to interlocking arising from dense state of packing.