Abstract：The double-layer lining structure of soil aggregate backfilling layer and reinforced concrete structure is usually employed as anti-explosion-induced-collapse structure in the open-excavated underground civil defend projects. In the condition of the same explosion loading and the same total thickness of structures，the thicknesses of the soil aggregate backfilling layer and reinforced concrete structure are the major influencing factors of the performance of anti-explosion-induced-collapse structure. Field tests and theoretical analysis are carried out to determine the optimal structure thickness. The results show that the backfilling of low-resistance rock or soil materials has clear superiority in absorbing shock energy. The optimal thickness ratio and its application methods are given for several conditions.
