Model Test On The Effects Of Young Shotcrete Under Blasting Load

Large-scale similar model is used for the research on the effect of blasting load onyoung shotcrete. According to similarity theory, similarity criterions of physical modelare founded, and similar materials are successfully developed. Then the testingprograms are systematically designed. The strength of similar concrete lining ismeasured by method of the embedded parts. Combined with resistance strain gauge test,the effect of blasting load on quality of shotcrete strength development is analysed fromthree aspects, including different age of shotcrete, various distances to tunnel face anddifferent positions in the same section. In this test, acoustic testing technique is appliedin the study on damage effect of blasting on shotcrete. According to the measure results,the quantitative relation between reduction rate of sonic velocity and blasting damage ofshotcrete is founded; also the damage accumulation of shotcrete lining after blasting areobtained. The statistical relation, among sonic velocity in shotcrete, blasting damageand blasting times is researched, and the regularity of sonic velocity variation withblasting times is figured out, but also the regularity of blasting damage with blastingtimes.