Research of asphalt-cement materials used for shield tunnel backfill grouting and effect on anti-seismic performance of tunnels

Backfill grouting is a key technology in shield tunnelling, and in this study, the process of backfill grouting in stable strata and soft soil strata was analyzed. Through a series of laboratory tests, asphalt-cement (A-C) materials suitable for backfill grouting of shield tunnels were investigated. Regression fitting equations were established between the proportioning of raw materials and the grouting performance indexes of A-C materials by multiple regression analysis. Then, based on a practical engineering, the adaptability of A-C materials under different formation conditions was studied from the perspective of anti-seismic performance, and a comparative analysis with conventional backfill grouting materials was conducted. The results show that the relative displacement peaks of the tunnel lining under seismic action did not change significantly after backfill grouting with different materials. Backfill grouting with A-C materials can reduce the maximum principal stress peaks of the tunnel lining by up to 54%, and A-C grouting materials are recommended for backfill grouting in the stable stratum section. The use of this material can improve the anti-seismic performance of shield tunnels compared to conventional backfill grouting materials.