Study On Dynamic Response Law Of Loess Slope Under High Energy Dynamic Compaction

With the rapid development of China's social economy,the scale and construction speed of projects are increasing rapidly.In order to improve the efficiency and depth of foundation treatment,high energy dynamic compaction is increasingly used in engineering practice.In this paper,based on engineering practice,field monitoring and numerical simulation techniques are used to conduct in-depth study on the dynamic response law of loess soil slope under high energy dynamic compaction.The main conclusions and results are as follows:(1)The results of dynamic finite element analysis show that with the increase of the compaction energy level,the frequencies of the vibration waves propelled by dynamic compaction are concentrated within 10 Hz at the near field and within 5 Hz at the far field.The peak velocity response appears in the range of 1~5 Hz.The consistency of the frequency characteristics of the vibration velocity and the attenuation law of the vibration velocity obtained from the field monitoring and numerical simulation are very good.(2)The modal analysis results show that the natural frequency of the loess slope decreases with the increase of the height of the loess slope.When the loess slope height is greater than 60 m,the natural vibration frequency of the loess slope of the first 10 vibration mode is smaller than that of the dynamic compaction vibration frequency.Therefore,it is less likely that the loess high slope will be destroyed under the dynamic compaction vibrational load.(3)The analysis of the harmonic response of loess slope with height of 8m has found that the resonance of loess slope is excited only in the first vibration mode under the action of high energy dynamic compaction vibrational load,but there is no obvious resonance effect in the high vibration mode.When the frequency range is from 1 ~5Hz,the slope vibration displacement response is large.(4)The results of numerical simulation show that the closer the slope point is to the foot of the slope,the greater the dynamic response peak value of the loess slope,and the slope surface peak value is greater than the slope body interior;Under high energy dynamic compaction vibration loads,with the increase of elevation,the dynamic response of the loess slope decreases rapidly with a negative exponential law,and the peak of the dynamic response of the slope within the height range of 12 m above the slope foot has amplifying effect,so the protection of this part of the slope should be strengthened.(5)When the elastic modulus of the filled earth is 8~10 MPa,the dynamic response of the loess slope reaches a maximum.The change of filled earth density has little effect on the dynamic response of the slope.When the depth of bedrock is 8~10m,the dynamic response of the first step shoulder of the slope reaches a maximum value.