Study On The Mechanical Properties And Strength Evolution Characteristics Of Aeolian Sand Filling

Due to the rising demand for mineral resources,the problem of goaf is more and more serious.Filling mining technology has been greatly developed in recent years because of its convenience,high efficiency and safety.It is an important means of Goaf Management.The technology mainly relies on the artificial column formed by the filling body to provide support for the roof of the mining area and ensure the safety of the mining area.Therefore,it is conducive to the study of filling body mechanics and strength evolution characteristics,which is conducive to understanding of the stress deformation characteristics of the filling,and revealing the changes in damage during the stress of the filling,providing a foundation for mine mining work and theoretical research.In this study,combined with the filling example of Yongle coal mine,analyzed the mining status of Yongle coal mine,and described the material selection,proportion selection,filling technology and economy in the filling work.Aeolian sand,loess and cement are selected as filling materials,and their physical and mechanical properties are measured and studied.The uniaxial compression test of filling body was carried out by MTS electronic universal testing machine,and the stress-strain curve was drawn to analyze the influence of different material ratio,mass fraction and curing time on the mechanical properties of filling body.Then,the damage constitutive equation was deduced by using the damage mechanics theory and strain equivalence principle,and the three-stage strength evolution model of aeolian sand filling body is constructed.The correctness of the model is verified by comparing the test curves.Through laboratory test and theoretical analysis,the main conclusions are as follows:(1)Filling body strength and the mass fraction,the maintenance time is positively correlation,and the mass fraction of 82%is higher than 80%higher than 80%,which is higher than 78%.The longer the maintenance time,the greater the strength of the filling,the greater the growth rate.The ratio of the three places of sand,the loess and cement is 4:1:1,the strength of the fill is the largest,the third ratio is 6:1:1,the strength value is minimal.(2)The stress-strain curve can be divided into four stages:pore compaction stage,elastic deformation stage,crack initiation and propagation stage and post peak stage.On the whole,the larger the peak strength is,the larger the slope of the curve is,and the smaller the required strain is.(3)The failure mode of aeolian sand filling body has nothing to do with its ratio,concentration and curing time.The stress state changes from one-way to three-way,and finally to one-way.After compression,the failure mode is X-shaped shear failure.(4)Analysis of the filling strength evolution characteristics,the theoretical curve of the structured equation is consistent with the variation of the test curve obtained by uniaxial compression,good fit,demonstrate the stress-strain curve characteristics of the stress-strain curve under the single-axis compression It can be confirmed by three-stage intensity evolution.