Uniaxial and triaxial tests of foam concrete show that the foam concrete which has the capacity of high compressibility can be used as filling material between primary support and secondary lining in deep soft rock tunnel. And the effects of this filling material which is called preset deformations layer on long-time stability of Yi-Ba expressway is studied. The results show that the creep deformation of surrounding rock in deep tunnel still increase after the construction of secondary lining; and it is hardly to be controlled by the method of increasing the thickness of lining; besides

the secondary lining is more easily destroyed by deformation pressure. However

preset deformation layer of foam concrete is able to decrease the deformation pressure on secondary lining by absorbing the creep deformation of rock. As a result

long-term stability of deep soft rock tunnel can be guaranteed by much thinner secondary lining.