Abstract:

Prediction of the aging deformation of pile-soft rock composite foundation depends on the understanding of rheological mechanism and the description of the rheological model. The rheological mechanism of pile-soft rock composite foundation was researched by analyzing the aging characteristics of pile stress, tip resistance of piles, pressure in rock surface under pile cap, and deformation in the deep of soft rock through scale model loading creep test. Results indicated that the tip resistance of piles and the deformation of soft rock between piles are both with obvious aging characteristics. The decay creep of the composite foundation under engineering loads can be accurately described by generalized Kelvin model with five parameters. The values of the five model parameters are as follows: E_H=1.1 GPa, E₁=7.05GPa, η₁=929 GPa·h, E₂=9.03 GPa, η₂=28 GPa·h. The rheological parameters of the composite foundation are significantly higher than those of soft rock foundation.

Key words: pile-soft rock composite foundation, scale model, creep test, rheological mechanism, generalized Kelvin model