NDRC Micro-tunneling work for DEWA 132 kV cable laying

The project works included Horizontal Directional Drilling (HDD) for installing electrical cables. The tunneling was to be done underneath the existing Sheikh Zayed Road road and Emirates Tower (Red Line) Metro piers. The project also included testing and commissioning 132 kV cable laying and associated works for 132/11 kV substations. 

The horizontal directional drilling technique is needed to construct launching and receiving shafts at both ends. The shafts required excavation up to 6 m depth below ground level. 

As the project required the construction/excavation of a shaft just adjacent to Red Line Metro piers and tunneling across Sheikh Zayed Road and the metro pier, instrumentation was planned for the safety monitoring of structures and the risk management of construction works. 

Encardio-rite’s sister concern, Encardio-rite Geosystems LLC in UAE, was instructed by the Road and Transport Authority (RTA-Owner of Metro structure) and Riyadh Cable Group Company to provide instrumentation and monitoring programs during NDRC to assess the impact on adjacent structures including the Dubai Red Line Metro pier and existing road, as per M/s RTA code of practice. Scope of works included:

• Pre-construction building condition survey of metro piers and its viaduct.
• Supply of geotechnical instruments, precise survey instruments 
• Installation of geotechnical instruments, including subsurface instruments 
• Manual and automatic monitoring
• Precise leveling 
• Setting up an online web-based data management system (WDMS) and maintenance during the contract period
• Daily & weekly reporting with evaluation & Interpretation

Instrumentation included:

• Instruments for Metro Pier monitoring
• An automatic vibration sensor was installed on metro piers to monitor any vibration caused by nearby construction works.
• Building settlement points Installed on metro piers to monitor any settlement caused by nearby construction works

Instruments for surface/sub-surface monitoring near construction works

• A Borehole extensometer was Installed to monitor subsurface settlement in the ground around the metro pier during tunneling.
• Surface settlement points are Installed in the soil to monitor surface settlement along the tunnel alignment and near the metro pier.

An experienced and proficient I&M team at Encardio-rite successfully installed and monitored the instruments mentioned above.