Influence of loading frequency and relative compaction on liquefaction behavior of reconstituted sand in cyclic triaxial tests 循环三轴试验加载频率和压实度对重塑砂土液化行为的影响

The article investigates the liquefaction behavior of saturated reconstituted sand by cyclic triaxial tests on isotropic consolidated undrained specimens in the laboratory. Experiments conduct using a sinusoidal load with a constant amplitude to evaluate the influence of the loading frequency (at three different frequencies of 0.1 Hz, 0.5 Hz, and 1.0 Hz) and relative compaction (three different relative compactions of 0.95, 0.90, and 0.80) on the liquefaction behavior of the sand, as measured by the shear modulus, damping ratio, axial strain, and excess pore water pressure ratio. Based on the experimental results, it can be observed that for the sand specimen with a relative compaction of 0.95, the loading frequency of 0.1 Hz has a negligible effect on the liquefaction process, as observed over 5 000 loading cycles. In contrast, the effect of this frequency is significant for the sand specimens with relative compactions of 0.90 and 0.80. For the specimen with a relative compaction of 0.80, an increase in frequency to 0.5 Hz results in almost direct liquefaction. This suggests that increasing loading frequency leads to faster liquefaction while increasing relative compaction results in slower liquefaction by contrast. Thus, through a series of tests, these can be considered simulations of the conditions of dynamic loads on the sand particles in the field with different frequencies. The experimental results show that the liquefaction behavior of saturated sand is determined by the following factors: (1) The lower the relative compaction, the easier liquefaction occurs; (2) The higher the loading frequency, the easier liquefaction occurs; (3) The greater the cyclic axial strain, the fewer cycles are required to cause liquefaction; (4) The excess pore water pressure increases with the increase of number of loading cycles until the specimen is completely liquefied. © 2024 Biodiversity Research Center Academia Sinica. All rights reserved.