Document Type

Thesis

Date of Award

5-31-1981

Degree Name

Master of Science in Civil Engineering - (M.S.)

Department

Civil and Environmental Engineering

First Advisor

Raj P. Khera

Second Advisor

Edward J. Monahan

Abstract

Determining the shear strength behaviour of a very stiff calcareous clay in the Direct-Simple Shear tests is the purpose of this thesis. The clay tested is the MLK Arderten Clay from West Germany.

For the Direct-Simple Shear tests, a trimming device was prepared to get the required size of the samples. Porous stones with nails were used to prevent the slippage of the samples.

The results of the Consolidated Ko Undrained Direct-Simple Shear tests showed that the shear strength of the clay depended largely on the condition of the samples tested. Relatively homogeneous and intact samples had shear strength values of 6-6.5 kg/cm2 at horizontal planes. Samples with cracks and fissures had 20% less shear strength values, and that for layered and varved samples, the reduction in shear strength was about 50%. The shear strength values of MLK Anderten clay are high because of the low water contents, Wn = 18 - 18.6%, and the presence of large amounts of calcium carbonate, apparently playing the role of a cementing agent.

The maximum past pressure to which this clay was subjected was determined to be around 7 kg/2, by using the normalized stress behaviour of the intact samples.

At early stages of testing and at low shear strains, local and progressive failure occurred in the samples which was more obvious in the cracked and varved samples.

The values obtained from the CKoUDSS tests present a useful measure of shear strength for analysis of field conditions which involve loading resulting in application of shear stresses to horizontal planes.

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