In the light of the not unified present situation of the tunnel health criterion

using lab similar model test and combining with engineering practice

the failure law and ultimate bearing capacity of surrounding rock with supporting structure in the state of deficiency in lining thickness are studied; and the health criterion under corresponding force state is concluded. The results show that the displacement character of lining is spandrel inpressing and vault extruding; contact stress decreases gradually between lining and surrounding rock; structure bearing capacity gradually decreases with the deficiency in thickness increasing; with the displacement increasing and the structural flexibility increases gradually; the inside vault was crushed and the outside crazed as tension action; subsequently

the hance and side wall appear cracks and propagation and coalescence at last. The results show that the bearing capacity curve expresses S-shaped characteristics; it can be divided into slow

fast and complete degradation basis on the variety of velocity; and it is uniform to the health grades and levels of tunnel structures so as to provide reference for engineering application