Application Research On On-line Measuring Technology Of Compactness In Vertical Vibration Roller

Compaction degree and compaction uniformity are two important factors determining road compaction quality.Vertical vibration roller is widely used in China because it has unique advantages in improving compaction degree and compaction efficiency.However,due to the restriction of many factors,the online compaction detection system has developed slowly in our country,and the existing on-line compactness detection system often appears the phenomenon of sharp fluctuation of detection index in engineering application,which has no obvious guiding effect on practical engineering.In this thesis,a series of basic tests have been completed,the feasibility of applying compactness on-line detection system to vertical vibrating roller have been explored,and analyzed the reasons for the violent fluctuation of online compactness testing index in practical application.Firstly,this thesis introduced the excitation principle and compaction mechanism of vertical vibration roller,and summarized the compaction characteristics of vertical vibration roller.Secondly,it introduced the routine and mature online test indexes for evaluating the detection effect of intelligent roller.Finally accomplished bench test of vertical vibration wheel-soil dynamic model,bench test of on-line measurement for compactness,vibration compaction test of vertical exciter-soil,on-line identification test of soil compactness by using vertical vibration test bench establishing based on dynamic model of roller-soil system,on-line measuring system of compactness and small vertical vibration roller.The test results show that the amplitude of the fundamental frequency component of the vibration acceleration of the vertical directional vibration exciter and the ECV value measured by the bench test increase with the increase of the stiffness of the bench.The frequency components of vibration acceleration and ECV values measured under the same working condition and different test times are relatively stable.ECV value test results show that the online compaction detection system works reliably.The frequency components of vibration acceleration of vertical directional vibration exciter measured under arbitrary graded soil settlement are stable.The identification results of soil parameters show that when the settlement of graded soil is 4 cm,5 cm and 6 cm,the stiffness of corresponding graded soil is0.612×10~6N/m,1.175×10~7N/m,1.786×10~7N/m,and the damping is 0.97×10~2N.s/m,0.50×10~2N.s/m,and 0.21×10~2N.s/m,respectively.The variation rule of ECV value obtained from on-line identification test of soil compactness and the correlation between ECV value and graded soil compactness show that the on-line detection system of soil compactness has a good application effect on a small vertical vibration roller prototype.Based on the test results of the frequency components of the vibration acceleration of the vertical directional exciter and ECV values,it can be inferred that the discrete and random fluctuation of the compacted parameters in each area of the compacted material can cause real-time and random variation of the high-order harmonic components of the vibration acceleration,which is an important reason for the sharp fluctuation of the compactness on-line detection index.