Study On Failure Characteristics Of Filling Body And Filling Body-Surrounding Rock Cementation Surface Under Different Curing Temperatures

For deep mine,high ground temperature is a factor that can not be ignored to affect underground mining environment.It is of great significance to study the changes of mechanical properties and failure characteristics of filling body cured in high temperature environment for exploring the mechanism of instability and failure of filling body and improving the production safety of deep stope.In this paper,the samples of filling body and filling body-surrounding rock are made from rod grinding sand and 325 cement.The samples is cured at temperatures of 20,40,60,and 80 degrees for 28 d respectively,and the basic physical parameters are measured.Uniaxial compression and acoustic emission monitoring tests,direct shear tests of different normal stresses,scanning electron microscopy of shear section and scanning section of the shear section are carried out.The mechanical properties,deformation characteristics and acoustic emission data of filling body and filling body-surrounding rock composite samples with different curing temperatures,as well as the fractal dimension and morphology characteristics of shear section were obtained to explore the influence of different curing temperatures on the failure characteristics of filling body and filling body-surrounding rock cementation surface.The results are as follows :(1)The results show that the density,moisture content and longitudinal wave velocity of filling body samples are closely related to the curing temperature,in which the density first increases and then decreases with the increase of curing temperature,the density of filling body reaches the maximum at 40 ?,and the density at 60 ? and80 ? is similar and lower than 20 ?;the saturated moisture content first decreases and then increases with the increase of curing temperature,and then decreases to the minimum at 40 ?;the longitudinal wave velocity increases with the increase of curing temperature.The longitudinal wave velocity is the highest at 40 ? and the lowest at80 ?.(2)The results show that the compressive strength and elastic modulus of the filling body increase first and then decrease with the increase of curing temperature.The compressive strength and elastic modulus reach the maximum at 40 ?,and decrease significantly at 60 ? and 80 ?.The peak strain is opposite to the variation of compressive strength and elastic modulus.The acoustic emission activity of the filling body in the process of uniaxial compression has obvious stage characteristics,which can be divided into three stages.Compared with normal temperature,the cumulative ringing count and cumulative energy of AE increase at 40 ?,and decrease sharply at60 ? and 80 ?,and the activity of AE decreases significantly.(3)With the increase of curing temperature,the shear strength and cohesion of filling body and filling body-surrounding rock composite samples first increase and then decrease,reaching the maximum value at 40 ? and decreasing to the minimum value at80 ?;when the temperature is constant,the shear strength and normal stress of the samples are positively correlated;the internal friction angle has no obvious correlation with the change of curing temperature;the shear stress-strain curve of the samples has obvious characteristics It can be divided into pore compaction stage,elastic deformation stage and failure stage.(4)The results show that the failure of filling body-surrounding rock shear section under different curing temperature and normal stress has good self similarity,and the fractal dimension of the section is negatively correlated with the normal stress;with the increase of curing temperature,the fractal dimension of the section first decreases and then increases,the fractal dimension is the lowest at 40 ?,the fractal dimension is similar at 60 ? and 80 ?,and higher than 20 ? and 40 ?.When the normal stress is 0,the main damage type of the section is spalling damage;after the normal stress is applied,the damage type changes to friction damage,and the larger the normal stress is,the wider the friction damage area is,the more concentrated the point height distribution is,and the lower the roughness is;when the curing temperature is 40 ?,the spalling damage degree of the section is significantly reduced,and the higher the point height is With the increase of temperature,the damage degree increases,the height distribution concentration decreases and the roughness increases.Sp,Sv,Sz,Sa and sq all decrease with the increase of normal stress.The relationship of these parameters is40 ?<20 ?<60 ?<80 ?,while Ssk does not show obvious correlation with the curing temperature and normal stress.Sku increases with the increase of normal stress.The relationship is 20 ?<60 ??80 ?<40 ?.