盾构隧道监测土压力匹配误差分析

盾构隧道施工中采用了特殊的工艺——壁后注浆，包裹了隧道表面预埋设的土压力计，壁后注浆对土压力计的包裹将影响其监测结果的可靠性。在注浆体力学试验基础上，建立能考虑注浆体固结硬化过程的有限元模型，探讨注浆体层的包裹对土压力计监测结果的影响。注浆体注入盾尾空隙后，终凝前处于流动状态，具有较强调节土压力计部位局部土体不均匀沉降和畸变应力场的能力，监测土压力与实际较为接近，其匹配误差远小于通常地下结构表面监测土压力的匹配误差。

Analysis of matching error of monitored soil pressure on shield tunnels

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.