Study on Deformation Characteristics of Young-Age Tunnel Shotcrete

摘要

Uniaxial compression tests and multi-stage stress relaxation tests for specially prepared young-age tunnelshotcrete were carried out. Comparing to previous studies, clip gauges were determined to be the best toevaluate elastic moduli of young-age tunnel shotcrete. Uniaxial compressive strength and 33% secantmodulus were larger than those of base concrete till 1 day, however, they became less than those of baseconcrete after then. Uniaxial compressive strength and 33% secant modulus till 1day showed a linearrelationship. This means that 33% secant modulus could be determined from uniaxial compressive strengthwhich is routinely determined at tunnel construction sites. In the multi-stage stress relaxation test,displacing rate significantly affected 33% secant modulus. This will result in significant change in support response to rock mass deformation. Stress decrease by yielding and stress increase with curing time even after the yielding were observed for slow loading multi-stage tests. The above findings will help to design reasonable tunnel supports through precise stress analyses around tunnel faces.