Abstract: Back-filling grouting, a special craft adopted by the construction of shield tunnel, enwraps the pressure transducer embedded on the surface of tunnel, whose effect on pressure transducer will determine the reliability of the monitored pressure. On the basis of the mechanical test of backfill grouting, the finite element model considering the hardening of grouting has been established; and the effect of the hardening of backfill grouting on monitored pressure has been analyzed. After it is injected into the shield tail gap, which is in the status of fluid in short period, the backfill grouting has strong ability of adjusting non-uniform settlement and non-uniform stress of the local soil near the pressure transducer, which leads to the approximation between the monitored pressure and the actual one. So the matching error of pressure transducer on the surface of shield tunnel is far less than the one of the common underground structure.

Key words: shield tunnel, backfill grouting, soil pressure, matching error