钱江隧道管片拼装过程中的力学行为实测分析

钱江隧道是目前世界上最大直径的软土盾构法隧道工程之一。通过在典型地层深埋段埋设全断面的隧道试验环,对盾构拼装管片的全过程及拼装后管片结构的受力特征进行了现场实测。监测结果表明,管片结构内力在拼装过程中受到管片相对位置及相互接触关系的变化影响,经历了波动、微调整直至平衡状态的变化过程。多数管片在拼装阶段的实测内力小于正常使用阶段管片理论内力的30%,但高于拼装阶段管片内力的理论值,最高可达到拼装阶段理论值的10倍以上。管片拼装过程中的内力实测值经历了波动或跳跃后逐渐逼近拼装阶段的理论值。值得注意的是,实测值的变化曲线表明:个别管片局部内力出现突变,实测突变值达到正常使用阶段理论值的3倍以上。因此,尽管管片之间通过管片间接触条件及相对位置的调整使管片结构的内力较快调整至正常状态,但该过程中出现管片内力局部过大的情形对管片结构的耐久性和长期承载性能可能造成影响,在今后的设计和施工控制中应予以充分考虑。

Field tests on mechanical behaviors during assembly of segmental linings of Qianjiang tunnel

Qianjiang tunnel is one of the soft soil shield tunnels with the largest diameter by now. In order to obtain the detailed mechanical behaviors from construction to service stage, field tests on the whole ring at the typical formation are carried out. The internal forces of linings are measured step by step during the whole process of assembling stage. The results show that the internal forces of linings are influenced by the variation of relative positions and contacts between segments, and fluctuate and are slightly adjusted and finally reach a new equilibrium state. Most of the measured internal forces during assembly of segments are usually 30% less than of the theoretical values in service, while higher, even more than 10 times, than the theoretical values during assembly. The measured values gradually approach to the theoretical ones during assembly after different levels of fluctuations or jumps. It is important to note that the variation curves of monitoring data have some individual mutations, and some even more than 3 times the theoretical values at service stage. By adjusting the relative contacts and positions between segments, the mutations return to be normal quickly. However, this process, causing local high stress possibly, has an influence on the durability and long-term bearing capacity of segments. The above characteristics should be considered carefully during the design and construction of similar projects in the future.