| Intelligent compaction and continuous detection technology effectively solve the defects of traditional subgrade compaction methods,significantly improve the subgrade compaction quality and control level,and its application and development prospect are extensive.However,at present,there are few research results are conducted in this technology,a lack of theoretical model and stability evaluation index for accurate control for intelligent compaction quality remains,and its feedback regulation mechanism is rough,so it is hard to carry out the construction and quality control of intelligent compaction in subgrade.In view of the above problems,by means of theoretical analysis,numerical simulation and field test,this paper systematically carries out the research on the dynamic response and quality evaluation feedback theory of intelligent compaction of subgrade soil,and forms a systematic theoretical method of intelligent compaction and continuous detection.The main research contents and results are as follows:(1)The dynamic model of subgrade single point vibration with dynamic changes of subgrade compaction parameters is established,the influence law of dynamic response factors on vertical displacement is clarified,and the dynamic response mechanism under single point vibration is clarified,which provides theoretical support for further rolling compaction analysis.The results show that the self weight of the roller and the amplitude of the exciting force are positively correlated with the vertical displacement of the subgrade,and the exciting frequency is negatively correlated with the vertical displacement.The influence of the self weight of the roller is the most significant.The self weight roller under the mode of low frequency and large amplitude of the exciting force should be selected for the rapid compaction of the subgrade.(2)Based on the secondary development of ABAQUS finite element,the dynamic numerical model of subgrade rolling compaction with dynamic parameters is established,and the influence law of different roller parameters on compactness and compaction meter value(CMV)is revealed,which provides data support for the subsequent establishment of compaction quality evaluation method and feedback adjustment mechanism.The results show that in the process of rolling compaction,the number of rolling passes has the most significant effect on the final compaction degree and CMV,and the excitation frequency has no significant effect on the final compaction degree and CMV.The excitation force has little effect on the final compaction,but has a significant effect on CMV.(3)Based on the numerical calculation results,the compaction measurement index CMV is optimized and the intelligent compaction quality evaluation index(AICV)is formed.Then,using the normal distribution 3σ criterion and the spatial statistical semi variogram method,the uniformity judgment and spatial correlation analysis method based on AICV index are proposed.The results show that when considering the existence of high-order harmonics,compared with CMV index,AICV index can consider the impact of high-order harmonics on subgrade compaction quality and has higher accuracy.In terms of compaction quality uniformity evaluation,CMV and AICV indicators are in the interval(μ-3σ,μ+3σ),which meet the requirements of compaction quality uniformity.In terms of spatial correlation analysis of compaction quality,CMV and AICV can effectively characterize the spatial influence range.Based on the above research conclusions,a comprehensive evaluation method of compaction quality based on CMV and AICV indicators is finally formed.(4)Combined with the results of rolling compaction numerical analysis and intelligent compaction quality evaluation,the combination of construction parameters to achieve the target compaction quality is optimized through multiple nonlinear regression and neural network construction.Combined with the predicted and measured compaction quality evaluation indexes,the judgment standard of feedback adjustment is put forward;Using range analysis and neural network method,the feedback adjustment method of input parameters is proposed,and finally the intelligent compaction feedback adjustment system of subgrade is formed.The results show that the proposed intelligent compaction feedback adjustment method has the characteristics of real-time and accuracy.Meanwhile it guides the dynamic adjustment of construction parameters in the process of subgrade compaction,so as to significantly improve the construction efficiency of subgrade compaction. |
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