The long-term heap unloading of heavy industrial plants will cause problems such as excessive accumulated settlement of clay foundation. To reveal the disease mechanism, it is necessary to explore the mechanical properties of soft clay in low-frequency cyclic triaxial tests. In this paper, a series of one-way low-frequency cyclic triaxial tests under different confining pressures, cyclic load amplitudes, drainage methods, and loading-unloading methods were carried out to study the accumulated axial strain, excess pore water pressure, and post-cyclic undrained shear strength of soil samples. The test results reveal that: (1) The relationship between the axial strain of clay and the number of cycles can be described by logarithmic function model. The accumulated axial strain increases with the increase of Cyclic Stress Ratio (CSR). (2) During the strain-controlled loading cycle stage, the peak deviatoric stress drops continually, with an attenuation rate of less than 30%. (3) Excess pore water pressure ratio U and CSR have a linear connection. According to CSR and other indicators, the excess pore water pressure ratio may be expected. (4) The undrained strength of the soil sample increases to 1.5~2 times after the drainage cycle, and the stress path shifts to the right. The stress path shifts to the left after the undrained cycle, but both are near the critical state line. The test results can provide a reference for the prediction of the long-term mechanical properties of soft soil foundation under the condition of long-term repeated loading and unloading.
Zhang Xi
,
Shangguan Shiqing
,
Yang Min
,
Li Weichao
. Experimental Study on Low-Frequency Cyclic Mechanical Properties of Soft Clay[J]. Chinese Journal of Underground Space and Engineering, 2024
, 20(S2)
: 664
-673
.
DOI: 10.20174/j.JUSE.2024.S2.18
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