Vibro-fluidization of sand under coupled static loading and high-frequency cyclic loading

Abstract

An increase in the operation speed of high-speed trains often leads to an increase in the loading frequency on subgrade soil. Hence, the long-term dynamic behavior of the subgrade and the service performance of high-speed tracks are affected. To determine the stress-strain characteristics of granular soil under high-frequency loading, a triaxial test setup was modified to investigate the effects of loading acceleration and duration, water content, vibration frequency, cell pressure, and initial soil density. The experimental results indicate that there are reductions in axial stress and volumetric strain during high-frequency loading. The reduction in axial stress is as high as 40%, and that of volumetric strain, which is permanent, could approach 0.1%. The stress reduction, strain compression, and excess pore pressure are found to vary linearly with vibration acceleration when a/g>0.02. The reduction in strength and strains are found to depend on the loading acceleration and effective cell pressure, but independent of the loading duration, water content, frequency, and initial density. A threshold acceleration a=0.02g is observed, below which the changes in the shear strength and volumetric strain induced by vibration are negligible. At high vibration acceleration, the strain amplitude could increase, eventually leading to a collapse of the specimen.

Experimental and modelling investigation of vibration‐induced fluidization in sheared granular soils

“…However, there is no solid evidence supporting the existence of ‘viscous friction’, although Blekhman 37 proposed the concept of ‘vibrational force’ that has the nature of ‘viscous friction’. Denies and Holeyman 38 suggested the concept of ‘shaking pressure’ to explain fluidization in vibrated dry sand. Nevertheless, the mechanism of ‘shaking pressure’ and its quantification are still in debate.…”

Theoretical method for additional horizontal stress of isolation piles due to adjacent loading

“…The distribution of ultimate soil pressure on the pile was composed of triangular distribution and parabolic distribution 11,12 . The ultimate soil pressure could be calculated by empirical method, and its maximum value was proportional to the soil undrained shear strength 13–17 . In addition, some studies paid attention to the lateral bearing capacity of piles under different loads 18–22 .…”

“…11,12 The ultimate soil pressure could be calculated by empirical method, and its maximum value was proportional to the soil undrained shear strength. [13][14][15][16][17] In addition, some studies paid attention to the lateral bearing capacity of piles under different loads. [18][19][20][21][22] Accounting for interaction between pile and soil, p-y method was used to obtain the stress characteristics.…”

Alternant active and passive trapdoor problem: from experimental investigation to mathematical modeling

“…Suffering from some accidents (e.g., ground subsidence, leakage), the subsided drainage pipelines need to be restored and uplifted using the polymer grouting technology for its long-term operation [17,19]. The anchor to support offshore floating energy converters inevitably bears wave cyclic load in the whole life cycle [15,32]. The buried power transferring pipeline subjected to high pressure and temperature may be relieved by upheaval buckling and offset the original position [11,39].…”