| Impact rolling compaction technology in South Africa,1995 from Hongkong into China,is the use of non-circular impact wheel rapid rolling impact shallow soil subgrade reinforcement,shallow foundation reinforcement technology is a kind of high efficiency and low cost.Compared with the static compaction and vibratory compaction the impact rolling technology has the characteristics of high amplitude,low frequency,has obvious advantages in shortening the construction period,save project cost and increase the subgrade reinforcement effect.At the same time,the impact roller compaction technology has less carbon emission,and it is a kind of physical strengthening technology which is beneficial to the environment harmony.According to Shaoxing Binhai Industrial District of Sanjiang Tong Highway project to tower a construction section,field tests of impact compaction technology of highway subgrade compaction,through the test site monitoring element buried soil pressure box and acceleration sensor to monitor the different depth of the soil pressure,the impact of rolling process on the ground acceleration.The subgrade soil under impact effect of impulse wheel vibration wave force distribution and the impact on the surrounding environment research.The field test results show that:(1)the soil dynamic stress in vertical direction is a transient non periodic pulse propagation in the soil,and the negative power function attenuation,and the attenuation of subgrade within the depth of 0.5~1.0m in most 1.0~1.5m depth attenuation is relatively less;(2)value the impact of small dynamic stress in the horizontal direction of the soil in 0.5~1.5m depth,attenuation,and the influence range of impulse wheel motion direction before and after the impact wheel is about 1.0m,the vertical direction of the influence range of more than 1.0m;(3)within the horizontal distance 1.5m,impact vibration generated is very strong in the 4m area within the attenuation more than 4m,stable attenuation,impulse wheel with 8km/h speed,safety distance is 5.3m,the safe distance of 10km/h velocity is 6.6m,10km/h is 7.3m,the safe distance with the impulse wheel There is a certain increase in the speed of motion.Simulation analysis of impact rolling explicit fill subgrade reinforcement process function using LS-DYNA software dynamic nonlinear finite element method,further study on stress distribution and attenuation along the depth direction and horizontal direction should the impact effect of impact rolling process in soil,and through the parameter analysis of influence factors on the impact compaction effect(the impact of wheel speed,compaction times and subgrade soil elastic modulus,cohesion and other factors)are studied.Numerical simulation results show that:(1)study the simulation results verify the field test conclusions,and found that the distance of 0.5m and 1.0m within the scope of the impact,the impact of soil impact at the moment of impact round a certain range near the soil uplift,and perpendicular to the moving direction of wheel impact effect is generated along the soil along the shock wheel movement direction;(2)the impact of stress depth with the increasing number of times of rolling dynamic impact produced by the soil and growth,increase the role of the depth of the impact compaction effect with the rolling times have a certain growth in the subgrade on the impact rolling times in the best 20~25 times;and(3)settlement stress with impact of wheel speed increases to a certain growth in the soil,but the impact of wheel speed will lead the impact rolling motion in the later stage of instability,thus determining the best impact rolling speed on Subgrade Between 2.5m/s~3.0m/s;(4)the soil dynamic stress under close settlement decreases with increasing the elastic modulus of soil,soil dynamic interaction depth stress influence depth and impact compaction effect has no obvious trend;(5)the stress influence depth with cohesive force increasing in soil effect of impact compaction effect,depth with the cohesion decreases. |
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