Model Test Study Of Mechanical Properties And Damage Evaluation Of Frozen Rock Under Blasting Load In Northwest China

In order to reveal the damage distribution of frozen rock under blasting effect, themicrostructure of country rock was analyzed in mines which were tunneled by the freezing-blastingmethod, and the microstructure properties of typical rocks in the northwest were gained. Therelationship of strength and confining pressure of frozen rocks were gained through triaxial tests.The threshold value of accelerated creep stage of frozen red sandstone was gained through creeptest under negative temperature, and the creep constitutive equation of red sandstone wasestablished. The relationship of dynamic strength and strength ratio of frozen red sandstone wasproposed by SHPB tests. A model was constructed according to similarity theory, and the frozenmodel was tunneled by blasting method. Three velocity sensors were arranged at specific sites tomeasure the vibration of rocks. The parameters、in vibration equation were gained byregression analysis, then any point’s vibration velocity in the model can be predicted. Someultrasonic detecting pipes were embedded beforehand in the model, and the ultrasonic detectingarea between two neighbouring pipe was detected respectively before and after each blasting. Thedamage distribution of the model was gained. Some strain blocks were embedded in advisable sitesin the model, and then the curves of strain-time were gained by means of dynamic resistance straingauge indicator. The relationship of strain and equivalent distance was gained.