Research On Vibration Compaction Characteristics And Compaction Technology Of Roadbed Fillers

Subgrade is an indispensable part of road engineering and the foundation of pavement structure.If the quality of subgrade is unqualified,uneven settlement deformation,pavement cracking,flatness reduction,rutting and other phenomena will often occur.Vibration compaction of subgrade fillers is one of the effective methods to prevent the occurrence of diseases.Therefore,it is necessary to study the vibration compaction characteristics of subgrade fillers.Based on the ZFZQ-3 tender section of Zhengzhou-Fuyang Railway,this paper aims at the problems existing in the study of vibration compaction of subgrade fillers,such as the lack of close connection between indoor test and field vibration compaction schemes,and problems in FEM numerical simulation of subgrade vibration compaction.The particle sieving test,natural moisture content measurement,shear strength test,compaction test and scanning electron microscope test of group A soil-rock mixed filler and group C cement improved soil filler used in construction site were carried out,and the basic physical characteristics of the two fillers were obtained.On this basis,indoor shaking table test was carried out to study the effects of vibration time,frequency and amplitude on the compactness of the filler.Orthogonal test was designed to analyze the sensitivity of the three factors.The order of influence level of these three factors affecting compaction degree is as follows:vibration amplitude>vibration time>vibration frequency.On the basis of indoor test,theoretical deduction is carried out,and a vibration compaction scheme of subgrade fillers based on energy conservation is proposed.Under the guidance of the proposed scheme,field vibration compaction test is carried out.The compaction degree standard of fillers is determined by the determination of compaction coefficient,dynamic deformation modulus,foundation coefficient and 7-day unconfined compressive strength,which verifies that the compaction degree of filling has been reached after vibration compaction.The rationality of the scheme is verified.Finally,the finite element model of roadbed compaction is established by using FLAC3D software,and a simulation method of moving vibration is proposed.The numerical simulation is carried out according to the roadbed vibration compaction scheme based on energy conservation,and the following conclusions are drawn:(1)Seismic loosening may occur in the local area near the seismic source on the roadbed surface at the beginning of vibration compaction.(2)As energy dissipates in the process of transmission,the deeper the packing is buried,the smaller the vertical displacement after vibration compaction,reflecting that the deeper the compactness of the position,the more satisfied the requirements.(3)The compactness of the fillers on both sides is not as good as that of the middle fillers,so the overlapping rolling of the vibration wheel should be paid attention to in the construction.(4)In the numerical simulation,before the vibration compaction,the subgrade fillers undergoes sufficient natural consolidation,which results in that the compression of the fillers in the numerical simulation is less than that of the fillers in the actual project.(5)After simulation according to the proposed vibration compaction scheme,the simulation results can verify the proposed scheme based on energy conservation,and verify the rationality and feasibility of the scheme again from the point of view of numerical simulation.The results obtained in this paper directly link the indoor vibration compaction test of subgrade fillers with the construction scheme of vibration compaction,and better to achieve the purpose of guiding practice by theory.In addition,a new numerical simulation method of roadbed vibration compaction is proposed,which provides a theoretical basis for the formulation of roadbed vibration compaction scheme in the future,and has important practical significance for practical engineering.