Abstract:  To improve the compressive performance of the buffer layer of the antidislocation structure of tunnels and enhance their capacity to absorb large dislocation displacement when crossing active faults, a novel porous concrete buffer material composed of centimetersized super absorbent polymer(SAP) particles is proposed and developed. Singlefactor experiments are conducted to analyze the effect of the sand content, SAP volume fraction, and particle size of SAP aggregates on the physicomechanical properties of SAP concrete. The results show that the SAP volume fraction and sand content considerably affect the mechanical properties of SAP concrete, with various influence patterns. However, the particle size of the SAP aggregate has a relatively minor effect. Based on these findings, the material mixing proportions are optimized to obtain a novel buffer material with adequate mechanical strength, a large void ratio, and brittle failure characteristics. The mechanical properties of the proposed SAP concrete meet the requirements of the lining structure, with a significant increase in compressibility, and can be effectively used for the antidislocation structure of tunnels crossing active faults with large dislocation displacement.

Key words: active fault, tunnel buffer material, super absorbent polymer concrete, compressive strength