Abstract:

The pipeline monitoring can not be easily carried out when the pipelines parallel to doubleline shield tunnel or cross the tunnel during shield tunneling. As a result, the visible ground surface settlement monitoring is regarded as the safety assessment factor for the shield tunneling safety. When the pipelines parallel to the tunnel, the relational expression between pipeline and ground surface settlement is established according to the deviation coefficient; when the pipelines cross the tunnel, the calculation model is established, and the angle between the pipelines and the horizontal axis and the distance between the intersection of pipeline and horizontal axis and the longitudinal axis are put forward, and the relational expression between pipeline and ground surface settlement is established. The pipelines are divided into continuous pipelines and discontinuous ones considering connecting modes of pipelines; the relational expressions between the strain of continuous pipelines and the ground surface settlement and that between the corner of discontinuous pipelines and the ground surface settlement are deduced respectively when the pipelines parallel to or cross the tunnel. Finally, comparison is made between predicted values and monitored data, and the results show that the abovementioned safety assessment method is feasible and can be carried out before shield tunneling.

Key words: doubleline shield tunnel, underground pipelines, safety assessment, parallel and intersection, ground surface settlement