Experimental Investigation On Dynamic Behaviour Of Soils Affected By Vibration Frequencies

Owing to the requirements on environmental protection in modern cities, the application of pile construction machinery which arousing environmental vibration in process of construction has been constrained. In order to alleviate the environmental impacts of piling driving in urban areas, piling with high-frequency vibration was developed and gradually used abroad over recent 10 years. However, there is little work focus on the soil dynamic characteristics in process of piling.In this thesis, the dry and saturated sands are employed to perform high-frequency vibration experiment test. It is also employed to perform cyclic tri-axial tests for saturated sand and saturated clay. The main contents are as follows:(1) Making the use of present instrument and equipment including static consolidation apparatus and electromagnetic vibration exciter to assembling a test system with high-frequency vibration. Its working frequency is between 18~2000Hz, and accuracy of deformation measurement is 1μm, and also can supply with dynamic load of constant peak.(2) A series of vibration compaction tests were done by "the system of high-frequency vibration experiment test" for dry sand of the relative density 33%,66%, under lateral confinement with vibration frequencies 18~42Hz. The relationship of dry sand between residual deformation and vibration frequency was investigated. The influence of relative density and amplitude of dynamic stress were also analyzed for the relationship between vibration frequency and residual deformation.(3) Experimenting on the "the system of high-frequency vibration experiment test" with saturated sand of different relative density and different amplitude of dynamic stress, the relationship between residual deformation and vibration frequency was investigated for saturated sand. Comparing the results with those of the dry sand and discussing the differences of residual deformation between saturated sand and dry sand were followed then.(4) The soil dynamic tri-axial test was employed for saturated sand and saturated clay with vibration frequency 2~10Hz under consolidation ratio 1.0 and confining pressure250kPa and 500kPa.The effect of vibration frequency were carried out emphasis on dynamic modulus, damping ratio and the change patterns of the generation of pore water pressure under different vibration frequency were analyzed.The research work presented in this thesis was supported by the National Natural Science Foundation of China with the granted number 50779034.