Tag
#metro
4 topics across all disciplines.
Prestressed and post-tensioned concrete
Why concrete is squeezed before it is loaded, the difference between pre-tensioning in a casting yard and post-tensioning on site, how losses eat a third of the force you paid for, and why a grout void inside a duct is the most dangerous defect in modern bridge engineering.
Segmental and precast construction
How a metro viaduct, a flyover or a warehouse frame gets built out of factory-made pieces — match-casting, launching girders, balanced cantilever, shear keys and grouted joints — and why the joints and the temporary condition are where the risk lives.
Tunnelling and segmental lining
How a metro tunnel is built — TBM types and why face support decides the machine, the precast concrete ring and its bolts and gaskets, annulus grouting, and the settlement trough that decides what happens to the buildings above.
Deep excavation and station boxes
How a metro station box or a basement gets dug in a city — diaphragm walls, secant and contiguous piles, propping and anchors, bottom-up against top-down, dewatering and base heave, and the instrumentation that tells you it is going wrong in time.