Proceedings of DFI-India 2019: 9th Conference on Deep Foundation Technologies for Infrastructure Development in India, (DFI)
Innovative Tunnelling Practices Adopted to Mitigate Various Execution Challenges in a Rail Tunnel Construction in India
Venkata S. Dronamraju, Ph.D., IRSE
As a part of 115 Km long new railway line project between Obulavaripalle and Krishnapatnam Port stations, two tunnels of 0.96 Km and 6.62 Km long were constructed using NATM method. The tunnelling posed various execution challenges interms of geology and terrain. Preliminary geotechnical and geophysical investigations were carried out and modern construction management techniques were used. The biggest challenge was to carry out tunnelling for a length of about 500m through low overburden locations of 4m to 6m in a forest and hilly terrain. Designers recommended cut and cover method and alternative methods were explored to avoid delay of Project completion. An innovative method of tunnelling was conceptualised and successfully carried out by ground improvement externally and controlled blasting with additional support system internally. Extensive monitoring was done with the help of instrumentation and total station survey both inside of tunnel and on ground surface during tunnelling. Faster execution through low cover zones resulted in savings in cost and time. Consequently, both the tunnels could be completed in record time of 25 months duly sustaining forest ecology and environment. The successful execution of these tunnels despite various challenges is expected to motivate all Tunnel Engineers and agencies to execute tunnel projects faster.
|article #3295; publication #1059 (India2019)|