Determination of Rheological Properties of Frozen Soils by Relaxation Method
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SOIL MECHANICS DETERMINATION OF RHEOLOGICAL PROPERTIES OF FROZEN SOILS BY RELAXATION METHOD
UDC 624.131.37 F. S. Karpenko,* R. G. Kalbergenov, V. N. Kutergin, V. P. Merzlyakov Institute of Environmental Geoscience, Russian Academy of Sciences, Moscow, Russia, *Corresponding author Email: [email protected].
This article discusses the possibility of using the stress relaxation method to determine rheological characteristics of frozen soils based on a multistage test scheme under triaxial compression conditions (using a stabilometer). The analysis of the test results shows that the proposed method has good application potential.
Introduction The rheological properties of many types of soils can be characterized by the dependence of the stress-strain state on the duration of the external loads. The rheological properties manifest more prominently and frequently in frozen and dispersed soils, and determine the course of two conjugate processes: creep and stress relaxation. The current regulatory literature [1] provides a method for determining rheological properties of frozen soils using a staged loading method in the creep mode, such as the long-term strength limit. According to Eshchenko and Chernyavsky [2], the application of stresses below the long-term strength limit of a soil cannot lead to soil degradation, regardless of the impact duration. If the limit is exceeded by some time, a progressive creep develops in the soil, characterized by an accelerated increase in irreversible deformation, resulting in destruction. The test procedures of the above method are complicated because of the duration and laborintensive nature of the experiments. Moreover, significant changes occur in the initial soil structure, which must be considered for accurate interpretation of test results [3]. In the 1960s, Goldstein developed the stress relaxation method for determining the rheological properties of soils [4]. Some of the theoretical and practical issues associated with determination of rheological properties of frozen soils using the relaxation method were considered in Ref. [5, 6]. In the process of stress relaxation tests, the accumulated irreversible deformation should not exceed the value of the total deformation formed in the initial loading stage at a given stress. Therefore, the possibilities of changing the soil structure are limited. In this case, the implementation of experimental tests is greatly simplified, and the time required for their execution is reduced. The stress relaxation method can be implemented under various loading conditions, such as compression, tension, shear, and triaxial compression. Tests under triaxial compression (using a stabilometer) have several advantages; they provide more information than other tests and can be used for frozen soils [7]. Despite these advantages, such a research method is not regulated by current standards, and
Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 5, pp. 7-11, September-October, 2020. 364
0038-0741/20/5705-0364
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