Construction of Surge Shaft by Slip Form for a 330mw Hydropower Project at Kishanganga in J&K

Abstract

Surge Shaft is one of the essential components in hydro power construction involving long running HRT (Head Raise Tunnel )so also with moderate to high head. It is generally a reinforced concrete lined, circular, open to sky or underground (but connected with tunnel opening to atmosphere), with a orifice slab at bottom where the HRT terminates and pressure shaft(s) (PS) begin(s), also with the controlling gate(s) for PS(s). Function of the surge shaft is to negotiate the sudden surge generally know as water hammer pressure generated due to rapid fluctuations in the flow of water through the tunnels. Slip form is a self-contained formwork system that may require little crane time during construction. It is an element used in method of vertically extruding a reinforced concrete section. In this construction method, concrete is poured into a continuously moving form. Slip forming(1) enables continuous, non-interrupted, cast-in-place flawless (i.e. no joints) construction which have superior performance characteristics to piecewise construction using discrete form elements.