Determination and influence of the unified strength theory parameter for loess
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ORIGINAL ARTICLE
Determination and influence of the unified strength theory parameter for loess Longsheng Deng1,2 · Wen Fan1,2 · Yupeng Chang1 · Siya Zhang3 · Shaopeng Liu1 Received: 6 September 2019 / Accepted: 14 September 2020 / Published online: 23 September 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The parameter b of the unified strength theory was set to depict the contribution of the intermediate principal stress on the failure of materials. A large number of true triaxial tests were carried out to determine the values and variation in the parameter b for loess, with which the effect of b on the estimation of the stability for a typical loess slope was then studied. The unified strength theory could be applied to fit the experimental failure loci of loess better than the traditional strength theories. The value of the parameter b greatly depends on the stratum age, remolding state, dry unit mass (dr) and water content (w) of the loess, and the appropriate value decreases with increasing dr and w. The value of b for the undisturbed Malan loess (L1) is much greater than that for the Lishi loess (L2). Comprehensively, the range of b = 0.2–0.5 is recommended to obtain the empirical value of the loess, with which the factor of stability (FOS) for the loess slope can be estimated with a 5–15% increase compared to that when applying the Mohr–Coulomb failure law. Keywords Loess · Strength theory of materials · The unified strength theory parameter · True triaxial experiment · Failure loci of loess
Introduction Loess is a special sediment consisting of silts transported and formed by the wind that covers an area of approximately 630,000 km2 in China (Sun 2005). In the field of * Longsheng Deng [email protected] * Wen Fan [email protected] Yupeng Chang [email protected] Siya Zhang [email protected] Shaopeng Liu [email protected] 1
School of Geological Engineering and Geomatics of Chang’An University, Xi’an 710054, People’s Republic of China
2
Key Laboratory of Western China Mineral Resources and Geological Engineering, Xi’an 710054, People’s Republic of China
3
Shaanxi Academy of Architectural Sciences, Xi’an 710082, People’s Republic of China
geotechnical engineering, loess is known as a “problem soil” due to its strong sensitivity to water and special mechanical properties, which can maintain nearly vertical slopes in a stable state when dry but is subject to instability when it reaches a certain critical water content. Research on the strength theory of loess has always been a popular topic for scientists and engineers. The primary mission of strength theory research is to explore the strength of a material and establish corresponding calculation criteria, with which the engineering stability can be evaluated. Considerable attention has been given by scientists to formulate the strength theory and failure criteria of materials. To date, many versions of these models have been developed, such as the Mohr–Coulomb, Tresca, von Mises, Drucker–Prager, Zienkiewicz–
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