Shear Strength Mobilized in Undrained Failure of Soft Clay and Silt Deposits

Mesri, Gholamreza
Huvaj Sarıhan, Nejan
In the early days of Soil Mechanics and Foundation Engineering, two important assumptions were made as a part of the limiting equilibrium stability analysis of undrained failure of soft clay and silt deposits. It was assumed that undrained shear strength is independent of the laboratory or in situ testing methods used to determine it, and that the shear strength mobilized in a full-scale undrained failure in the field is equal to the undrained shear strength measured by a laboratory or in situ test. However, during the latter part of Geotechnical Engineering, it was realized that these two assumptions, in general, are not correct because undrained shear strength is influenced by mode of shear, shearing time to failure, progressive failure, and soil disturbance. As these controlling factors are rarely the same for any two testing methods or for any test and a full-scale field failure situation, undrained shear strengths determined by various tests are expected to be different; and the laboratory and in situ test measurements must be corrected before they are used for stability analysis of full-scale field undrained failures. Using undrained shear strength data back-calculated from failures of embankments, footings, and excavations, and data from in situ and laboratory tests, the relationship of suo(mob) is reviewed to suo(FV), suo(UC), suo(TC), suo(TE), suo(DSS), and also to Nk from push cone penetration test.


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The relationship between shear strength and soil suction of compacted Ankara clay was investigated at different moisture contents. Soil samples were tested at optimum moisture content (w = 20.8%), drier than optimum (w = 14.8%, 16.8%, 18.8%) and wetter than optimum (w = 22.8%, 24.8%, 26.8%). Direct shear tests were performed. Soil suctions were measured by the filter paper method after direct shear tests. Direct shear tests and soil suction measurements were also performed on soaked samples. The soil suctio...
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Shear-wave velocity (V-s) offers a means to determine the seismic resistance of soil to liquefaction by a fundamental soil property. This paper presents the results of an 11-year international project to gather new V-s site data and develop probabilistic correlations for seismic soil liquefaction occurrence. Toward that objective, shear-wave velocity test sites were identified, and measurements made for 301 new liquefaction field case histories in China, Japan, Taiwan, Greece, and the United States over a d...
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Shear failures of interfaces between granular material and clay are frequently encountered in engineering practice. In earthfill dams, road embankments and spoil piles in mining operations, granular materials are placed on clay, and shear failures and/or large movements are observed along interfaces. When dealing with this type of a problem selecting representative shear strength parameters is difficult. Furthermore in the literature no accepted procedure is available to select these parameters. This study ...
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The response of sandy soils under monotonic loading depends on size, shape and mineralogy of particles, fabric, stress and density states of mixtures. Researchers around the world have studied their local sands and calibrated their responses (e.g., Toyoura sand-Japan, Ottawa sand-Canada, Sacramento sand-US, Sydney sand-Australia, etc.). However, there are not many studies that have focused on regional sands from Turkey. This research study aims to introduce a local sand, Çine sand, to literature as a "stand...
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Collapse of the residual soil over bedrock cavities often occurs during construction in karst terrain, particularly when the thickness of the residuum is reduced during excavation. Even if an estimate of the strength of the residual soil is known, uncertainty with respect to the size/geometry of the subterranean voids makes a detailed analysis difficult, and straightforward methods to check the stability are needed. In this study, numerical analyses were performed to develop a stability chart expressed in t...
Citation Formats
G. Mesri and N. Huvaj Sarıhan, “Shear Strength Mobilized in Undrained Failure of Soft Clay and Silt Deposits,” 2007, Accessed: 00, 2020. [Online]. Available: