Study On The Model And Parameters Of The Vibration Compaction Systems In The Soil Subgrade

With the increase of the traffic and vehicle load, the requirement for the compaction quality of highway is improved. The experiments show that if the necessary compaction is carried out on the highway subgrade, the non-permeability and strength stability of the subgrade soil and pavement material can be increased. The utility performance can be strengthened and the life of the pavement can be lengthened. For the vibration roller is superior to the same weight static roller in that good compaction quality and compaction efficiency, the vibration roller is widely applied in the compaction construction field.From the dynamic theory model analysis, experimental study, the analysis and treatment of the stress signals of the soil compaction and the finite element numerical analysis, the studies are carried out on the dynamic model of the soil vibration compaction system, the effect of the model parameters on the compaction quality, and the three-dimensional distribution and transmit of the stress and compaction energies in the soil, and the distribution characteristics of soil internal stress in deep.According to the dynamic theory of mechanical system, the "vibration roller-soil" models are presented. The dynamic analysis is carried out on two work conditions of near ground compaction and jump ground compaction during the vibration compaction. The calculation equation Fs of the dynamic force between the vibration wheel and the soil is derived. Based on the equation, the relation between the vibration parameters and the soil parameters, as for vibration frequency and vibration amplitude, and the compaction quality is analyzed.Through the vibration compaction experiments, based on the evaluation index of compactness, the law between the work parameters, such as the amplitude, vibration frequency and roller compaction velocity and the compaction quality is gotten. The effect of amplitude on the compactness is the most. The second is the compaction velocity. The effect of vibration frequency on the compactness is not obvious as that both the amplitude and compaction velocity. But the optimal frequency exists. Combing the established dynamic model, the soil stiffness and dampness are identified. The experiments showed that the soil stiffness increased with the dense of the soil. The soil dampness decreased with the dense of the soil. The more the soil stiffness is, the more the natural frequency of the vibration system and the acceleration of the vibration wheel. However the increase domain becomes small.The stress signals of the soil compaction are rich in the important information during the vibration physical progress. Through the time domain analysis on the soil stress signals, the distribution of the compressive stress in the soil and the absorption status and the transmit law of the compaction energy in the soil.The stress signal is unstable and transient salutation signals accompanied by strong noise, which are acquired from the soil by the experiments. To extract the ideal signal from the noise signals and study the joint time-frequency property of the soil stress signal during vibrating compaction, the wavelet transform method for de-noising and the singular value identification method are proposed. The time of the stress appearance and the time of the stress peak arrival can be calculated, further the function time. So the relation between the work parameters, such as the amplitude, vibration frequency and the rolling velocity, and the vibration rolling effect can be analyzed. The results show that the function time of stress on the soil is increased linearly to the amplitude, which decreased with the increase of the rolling velocity. However the high the rolling velocity is, the slower the decrease tendency is. The function time increase with the vibration frequency first then decrease. So the optimal vibration frequency exits.Combining the compactness test and the wavelet transformation and singular value detect of the soil stress signal, the optimal compaction parameters are that the amplitude is 1.6 mm, the vibrating frequency is 30-32 Hz and the roller compaction velocity is 1.12km/h～1.30km/h.To study the three dimensional distribution of the compact stress of the soil under the vibration compaction, the dynamic theoretical model is combined with the finite element method. The three-dimensional mathematic and dynamic model of the soil vibration compaction system is proposed for the first time. By the finite element method, the simulations of the vibration compaction of the soil are carried out. The simulated results showed that the distribution of the soil internal stress is uniform for the instantaneous region of the exciting force. Along the wheel width, the compact stress is not uniform. Along the compaction depth direction, the compact stress decreased little by little.This dissertation combined the theoretical analysis, experimental study and finite element simulation, which pave for the parameter optimization of the soil compaction, the improvement of the compaction quality and efficiency and discovering the compaction mechanism of the soil. The study is of importance in guiding the infield engineering construction of compaction.