Ingenieur July-Sept 2016 Ingenieur July-Sept 2016 | Page 25

Power Intake Figure 15: Murum spillway view post impoundment The intake tower is a reinforced concrete structure bank-tower type. There are two intakes; each with a design discharge capacity of 172m3/s and dimension of 50m wide x 18.6m long x 54.5m high (see Figure 16 and 17). The top and base surface elevation is 547masl and 492.5masl respectively with a total discharge capacity is 344m3/s. The intakes are controlled by a set of hydraulic operated fixed wheel gates that can close automatically under emergency conditions. The intake structure is protected by a floating log boom to stop debris or logs from impacting its performance by entering the intake. Murum Power Intake Type Surface Dimension 18.6m long x 50m wide x 54.5m high Rated Flow 172 m3/s per bay Power Tunnels Figure 16: Overview of power intake after construction. Intake for Tunnel No.1 on right. Figure 17: View of power intakes post Impoundment The twin 2.65km underground water tunnels connect the power intakes to the powerhouse. Each tunnel consists of a 1,445m long and 8m diameter upper horizontal section (see Figure 18), a 60m high, 25m diameter surge tank, a 174m long 6.2m diameter shaft and a 1,229m long 5.5m diameter horizontal section (see Figure 19). In-situ tests were carried out to determine the design parameters of the rock for the design of the concrete and steel liners, and to determine the extent of the steel liner. The in-situ tests carried out included plate load tests to determine in-situ deformation of the rock mass, hydro-fracturing and hydro-jacking tests to determine in-situ stresses of the rock mass, etc. Murum Power Tunnel 2 Concrete and Steel 8m to 3.4m 2.65km No. of tunnel Type of lining Tunnels diameter Length of tunnel 23