Work on the Jilin tunnel in China has celebrated breakthrough five months ahead of schedule after setting a new regional record by advancing 1,400m in one month in February.
The 24.3km long Jilin Lot 3 tunnel water conservation tunnel for Jilin Province Water Investment Group was driven by Beijing Vibroflotation Engineering Co using a Robbins Hard Rock Main Beam tunnel boring machine (TBM).
“The project broke through 147 days earlier than scheduled,” said Beijing Vibroflotation Engineering Co vice chief engineer and project vice general manager Wu Zhi Yong. “The project has achieved the fastest monthly advance rate record of 1,423.5m for an 8m diameter TBM in China. And the machine has reached over 1,000m per month for three consecutive months. I am so proud of these achievements.”
According to the company, achieving the breakthrough so far ahead of schedule is a monumental achievement considering the difficult ground conditions encountered. Rock types ranged from tuff to granite, sandstone, and andesite with multiple fault zones and required nearly continuous ground support. Rock strengths varied widely from 35 to 206MPa.
The Robbins TBM bored through a total of 24 fault zones using an innovative combination of steel McNally slats (extruded through pockets in the TBM roof shield to prevent movement of loose rock), wire mesh, and shotcrete. The TBM was specifically designed to tackle the tough conditions.
The tunnel forms a key part of China’s largest water diversion scheme – 736km in total – and will divert the water from Fengman Reservoir at the upper reaches of Di’er Songhua River to central regions of Jilin Province to overcome water shortages.