Study Of The Vibration Attenuation Effect Of Crossed Vibration Isolation Trenches On Roller-Induced Environmental Vibration

With the development of urbanisation,the road network in densely populated areas has tended to be saturated,in order to meet the growing demand for traffic,urban road reconstruction and expansion has become an urgent task.As an indispensable machine in road reconstruction and expansion construction,the environmental vibration problem generated by vibratory rollers during road compaction has been of great concern.Therefore,in order to reveal the propagation characteristics of environmental vibration induced by vibratory rollers,this thesis constructs a finite element model of vibratory roller-roadbed-foundation soil based on the coupled dynamics model of vibratory wheelroadbed,analyses the propagation law and vibration attenuation characteristics of vibration waves induced by vibratory rollers,and determines the best vibration isolation interval for environmental vibration induced by rollers.In order to clarify the band gap characteristics and vibration isolation effect of the periodic cross vibration isolation trench,the surface wave energy band structure is calculated by numerical simulation,the formation mechanism of the surface wave band gap is analysed,and the influence of the design parameters of the periodic cross vibration isolation trench on the complete band gap width is discussed.The vibration isolation effect of the cross vibration isolation trench under the vibration of the roller and the vibration isolation effect under different working conditions were investigated.The main findings of this thesis are as follows:(1)The frequency of roller-induced environmental vibration is mainly distributed between 0-30 Hz;the propagation distance x of vibratory roller-induced environmental vibration and the acceleration amplitude y1 conform to the attenuation model of y1=Ae-Bx function,and the frequency amplitude y2 conforms to the attenuation model of y2=Aex/B+C;the vibration response of medium-soft foundation soil is greater than that of weak foundation soil,and the attenuation degree of medium-soft foundation soil for vibration is less than that of The attenuation degree of medium-soft foundation soil is less than that of weak foundation soil;medium-soft foundation soil will cause more high-frequency vibration;as the hardness of foundation soil increases the resonance frequency of vibrating wheel and soil will also increase,the resonance frequency of weak foundation soil is 4.04 Hz and that of medium-soft foundation soil is 22.55 Hz.(2)For surface wave isolation of roller-induced environmental vibrations,effective isolation can be achieved by selecting a period constant of 2 m,a length of 1.9 m,a width of 0.5 m and a height of 2.3 m.The period cross g isolation trench has a period constant of 2 m,a width b of 1.9 m,a width c of 0.5 m and a height h of 2.7 m.The total full band gap width is a maximum of 4.89 Hz.The cross cavity height of 2.3 m gives the maximum band gap width in the Γ-X direction and a total band gap width of 7.36 Hz.(3)A vibration test rig was built and experiments showed that the vibration attenuation in the band gap of the periodic cross g isolation trench was significantly greater than outside the band gap,with a 70 % reduction in acceleration frequency in the attenuation interval,verifying the band gap characteristics and isolation effect of the periodic cross isolation trench.The complete band gap range of the periodic cross trench is influenced by the soil elastic modulus and the period constant.An increase in the soil elastic modulus leads to a shift of the complete band gap towards high frequencies;an increase in the period constant leads to a shift of the complete band gap towards low frequencies;as h/a increases,the number of modal orders in which the complete band gap appears increases and the modal order increases.(4)After the installation of the cyclic cross damping trench,the acceleration amplitude at the monitoring point was significantly reduced,with an acceleration amplitude reduction of approximately 68.5%.The vibration isolation trench has a significant effect on vibration isolation in the frequency range of 8-12 Hz and greater than20 Hz,and attenuates vibration at 27 Hz by 93.6%.At the same time,within 4 m of the cross damping trench,an attenuation zone will be formed,beyond which the vibration amplification phenomenon will occur and the acceleration vibration level will increase.Through the analysis of the vibration isolation effect of different rows of crosses,it is recommended that three rows of vibration isolation ditches be installed to achieve the optimum effect.