The Strength Change Rule Of Disturbed Clay Foundation

The strength of clay foundation will be attenuated after disturbance. Some even lead to destructions of buildings or infrastructures. Due to the multifarious disturbance form and difference of foundation’s surroundings, the strength changing mechanism of disturbed clay foundation(incuding strengthened clay foundation) is very complicated. The strength change rule of distured clay foundation is mainly studied in this paper through laboratory tests and theoretical analysis.Firtly disturb the clay samples by torsional shear and horizontal shear, obtain the shear strength parameters. Test results show that shear strength is reducted after disturbance. The reduction shows positive correlation with load amplitude and disturbing number.Quantitatively analysis the micro images through MATLAB programming. The results show that count, area fraction, roundness increase and the equiv diam decreases. The analytical result of grey correlation shows that the effect of equive diam on macroscopic strength is max, roundness, area ratio thereafter, and count is min. Finally, the function relation between the static strength change and micro structures is obtained by fitting.The strength variety law of disturbed cement strengthed clay is stuied by dynamic triaxial tests.The test result shows that the unconfined strength qu increases after dynamic strain’s disturbance and qu increases with the increase of σd. The effect of salt solution on cement hydration reaction is stuied. It shows that the qu of salt solution cement sample is stronger than clear warter cement sample, but with less time to reach peak. The qu of samples cured under salt solution decreases with the increase of age. The micro structure index is quantitatively compared by LeicaQwin5000. The analytical result shows that the count, area ratio,equive diam decrease and roundness, aspect ratio increase. The absolute change rate of solution cement sample is larger than clear warter cement sample.Through the above research, the strength change rule of distured clay foundation is summed. Corresponding microscopic parameters that influence the static strength are introduced and the micro macro link is established. Provide technical support and theoretical reference for further research and practical engineering.