IMPROVED PROCESS FOR THE CONSTRUCTION OF TUNNEL IN SOFT-GROUND

摘要

A process for the construction of tunnel in soft ground making use of multiple pre-cast and cost-in-situ units comprising the following steps of :-(i) excavation of a trench perpendicular to the longitudinal axis of the tunnel having lightly reinforced guide walls, the trench being filled with bentonite slurry during the entire grabbing operation maintaining it against collapse; (ii) excavating the bottom of the trench to a slightly greater depth than required so that gradients can be made up with a layer of lean concrete to form a good foundation for the tunnel rights; (iii) placing pre-cost concrete tunnel linking, into position by resting the projected area of the flat underside of the lining partly embedded in the lean concrete and them bake filling the trench after proper alignment and leveling of the element; (iv) excavating another similar trench at a distance of approximately one width away transverse to the longitudinal axis of the tunnel and then placing another said pre-cast concrete tunnel lining in position; (v) excavating the beam between the said two tunnel linings with the help of bentonite slurry and trench bottom correctly leveled; (vi) an intermediate ring of tunnel lining of cast-in-situ construction in the said intermediate runnel; (vii) is constructed by lowering reinforcement cage into position and the segment concrete using tremie concrete; (viii) after hardening of the concrete, backfilling the trench and the guide bars removed.