| Ultra-soft foundation with high water content and high void ratio widely exists in coastal regions of China and this kind of foundation can not be utilized until be reinforced. The static-dynamic drainage consolidation method is mainly used for the super soft foundation reinforcement because of its high quality, short construction period and high economic benefit. Study on impact effect is of great significance for the deep understanding of the reinforcement mechanism of static-dynamic drainage consolidation method when it is utilized in ultra-soft ground reinforcement. As a matter of fact, experts and scholars at home and abroad have done a lot of research on this, including in-situ monitoring and indoor model test, but the cost of in-situ monitoring is too high and the construction is interferenced easily. And there always exist a problem in the latter that the impact load level is not high enough so that the physical and mechanical properties of soil couldn’t be inspired, but indoor model test under impact loading of high energy can solve the above problems effectively.The impact of the energy use of multi-speed electromagnetic force intelligent control test equipment, w=70.48%, e=1.96.Ultra soft soil mechanical response under high energy impact effects, including pore pressure and earth pressure during laying sand and flapper period, tamping process pore pressure and earth pressure and settlement variations, surface vibration velocity attenuation law, etc. With the in-situ monitoring data were analyzed to verify the feasibility of the model test. Based on Terzaghi one-dimensional consolidation theory. Checking static and dynamic drainage consolidation method tamping formula instantly pore pressure change and edit Matlab calculation program.In this paper, the research achievements include the following aspects:(1) Under tamping action, The transmisssion earth pressure along the depth performant a clear time lag, Time of earth pressure increased to the peak is up with depth, obtained by curve fitting relations:t=-0.7396h2+10392h+20.701(ms).Time of earth pressure go to peak increased with tamping times tin the same depth.With increases of the number of tamping at the same depth, earth pressure increased to a peak time gradually increased.(2) At the moment of tamping, with the increase of distance from the centerline of the hammer, the increment of pore pressure reduced at the same depth. In the depth of20cm,13cm away from the centerline of the hammer pore pressure increment with the centerline were just a little different; while at depth33cm,13cm away from the centerline of the hammer and the pore pressure at30cm didn’t have fundamental changes.(3) Under the action of impact, maximum ground vibration velocity gradually decayed with the distance from the centerline of the hammer increased. Obtained by curve fitting relationship:Vmax=35.498x-0.8. At same distance from the centerline of the rammer, surface maximum vibration velocity increases with the number of tamping, After fifth times tamping was completed,1.25times the diameter of the hammer from the centerline, the maximum ground vibration velocity was very large, achieved6cm/s, proving that the advantages of high energy shock loading device. Ground vibration velocity and acceleration had the same variation and vibration speed lags behind the acceleration.Study found that when increasing the tamping energy fifth times, the model box super soft soil foundation earth pressure at depth of20cm increments was less than the depth33cm, and the6times also had the same variation rule, with the opposite change law in the first four times; tamping peak instantaneous pore pressure dissipates faster, drainage effect is ideal. |
