The Experimental Research Of Creep Characteristic And Long-term Strength For Cemented Full Tailings Backfill

The filling mining method can effectively dispose the underground goaf and control the ground pressure.The strength of filling body is a prerequisite to achieve this goal,and creep activity will have a certain effect on such strength,which indirectly affects the underground producting,so it is of great significance to study the creep characteristics and the long-term strength of the cemented tailings backfill body.On the basis of uniaxial compressive strength value,the creep test of full tailings cemented backfill specimen was carried out by uniaxial loading.After the test results were collected,the creep characteristics of the the creep constitutive equation is constructed and the long-term strength value of the backfill body is determined by the stress-displacement curve method and the excessive creep analysis according to the creep curve and the result,and the effect of the ratio of the lime sand on the instantaneous strength and the long-term strength of the backfill is analyzed.The main contents and conclusions are as follows:(1)RMT-150 c rock mechanics test system was utilized and uniaxial compressive test was carried out on the filling body,and the compression strength of the cylindrical backfill specimens with concentration 76,and lime sand ratio 1:4,1:6 and 1:8 were respectively 5.151 MPa,3.098 MPa and 1.922 MPa,and the elastic modulus were 980 MPa,702 MPa and 458 MPa,with the increase of the ratio of lime to sand,the strength of filling body increased,and the strength of the adjacent lime-sand ratio increased,and also the elastic modulus increased.(2)The damage evolution equation and damage constitutive model of 1:4,1:6 and 1:8 backfill specimens under uniaxial compressive compression were established.When the stressstrain curve of the specimen is stopped after the peak stress in the process of pressure test,and the degree of damage was less than 70 percent.The results show that the residual strength of the specimen is still present after the peak stress is reached,and the damage evolution equation and constitutive model of the backfill specimen with 1:4 in the creep state are established.(3)The long-term strength of concentration 76,lime sand 1:4,1:6 and 1:8 of filling body specimens were 3.81 MPa,2.67 MPa and 1.55 MPa,which accounted for 74,86 and 81 percent of the destructive strength,namely,the long-term strength of the total tailings cemented filling body measured in this test was 74 ~ 86 percent of the uniaxial compressive force.(4)The effect of lime-sand ratio on the strength will weak in the long term.In those effect factors to the strength of the filling body,the weight of lime-sand ratio in later period is less than the earlier weight,it also indicated that one or several other effect factors must exist,and the weight of filling body strength will increase in later stage.