Dynamic Characteristics Of Coal Gangue Subgrade Filler Under Traffic Load

Coal gangue refers to the waste rock discharged from coal mine construction,coal mining and processing.Along with the coal mining produces the massive accumulation and forms the gangue mountain,not only causes the pollution damage to the environment,also has the safety hidden danger itself.Therefore,the comprehensive utilization of coal gangue is an important practical task to be solved urgently.At present,there are two main ways of comprehensive utilization of coal gangue,namely,resource recovery and engineering utilization.In engineering utilization,coal gangue,as a filling material,also has strong bearing capacity,high structural stability and excellent engineering characteristics which are not easy to produce too large deformation and good water permeability when it reaches high density.However,there are few researches on the mechanical response,especially the dynamic response of coal gangue coarse grained soil.Therefore,this paper mainly aims at the coal gangue as subgrade fill dynamic characteristics of the study.A large-scale triaxial dynamic test was carried out on the coarse grained coal gangue soil samples by using DJSZ-150 dynamic and dynamic triaxial test system.In this paper,the "skeleton curve characteristic test" and "cumulative deformation test" are mainly carried out in view of the real conditions of coal gangue subgrade fill.The skeleton curve,hysteresis curve,dynamic modulus and damping ratio of coal gangue were analyzed under different influence factors.the experimental results show that the skeleton curve of coal gangue is obviously nonlinear with the increase of dynamic strain.at the same time,the dynamic modulus attenuates and the damping ratio increases gradually;with the increase of confining pressure,compaction degree and coarse particle content,the dynamic strain under the same dynamic stress will decrease.On this basis,the characteristic model of coal gangue skeleton curve is analyzed,and a bilinear model which can fit the characteristics of coal gangue skeleton curve under low dynamic load is proposed.The cumulative deformation test adopts the single-stage loading form of large number of times,and analyzes the change of the relationship between the cumulative axis change and the accumulative volume change of coal gangue and the earthquake times under different influencing factors.Experimental results show that with the increase of earthquake times,the cumulative deformation of coal gangue increases rapidly first,after 5000?8000 vibrations;the cumulative deformation curve tends to be flat,and the cumulative deformation of coal gangue decreases with the increase of confining pressure,compaction degree and coarse particle content.Based on the basic idea of volume change increment model,the cumulative deformation model is established,and the practicability of the model is confirmed by fitting and analyzing with experimental data.The experimental results can enrich the research data of the dynamic characteristics of the embankment fill of coal gangue,which is beneficial to explore the dynamic deformation characteristics of coal gangue,and provide a certain basis for the laying and use of the subgrade.