Inverted U section shutter lining for tunnels - has longitudinally uniformly increasing cross section

摘要

The shuttering unit can be struck after casting of concrete by moving it horizontally with the larger end leading. Pref. sectional profiles are semi-frusto conical or polygons. Each unit incorporates retractable wheels. Several units (12, 13, 14) with matching abutting ends (15, 16, 17, 18) and tapering in the same direction can be employed and the shutter is pref. used with a striking agent. The system can be utilized to construct an edifice, of rimless cartwheel shape in plan, each spoke taper increasing incross section from the hub.