Zhou Shunhua

New challenges in construction mechanicsof urban rail transit

This paper aims to raise concerns about construction mechanics. Firstly, operating railway transit at present and scales of ongoing rail transit projects are briefly introduced. Then, major constraints of urban rail transit construction are analysed in two aspects, including complexed geology conditions and strict environmental requirements. Difficulties caused by geology conditions contains excess settlement and overall failure in very soft soil, the delayed ground collapse and cutter wear of shield tunnelling in sandy cobble stratum, construction safety threats in complex stratum, water bearing stratum and gas-bearing stratum. About environmental restrictions, difficulties of constructions crossing existing railways, buildings and cultural relics are summarised. These difficulties challenge construction mechanics in failure behavior descriptions and calculation precisions. In the end, this paper considers that breakthrough in construction mechanics should be seek in mechanical models, shakedown solutions subjecting slight dynamic load, and multi-factor forecasting models.