Liucun tunnel, a most difficult tunnel constructed for Nanning-Chongzuo railway line.  119.3 kilometers railway line for high speed trains 250 kilometer per hour. In Guangxi region. China Railway 14th Bureau Group has won against major difficulties.

Liucun Tunnel is 5725 meters. Shield boring section is 4006 meters long. Diameter is 12.86 meters. One tube two railway lines in one tube. Xinhuan write a Slurry EPB Tunnel Boring Machine bore. Tunnel goes under 6 railways, 6 local roads, 1 subway, 12 buildings, 27 underground pipes.

In normalaty, it is simple TBM tunnel boring.  Liucun tunnel is not normal tunnel. Extreme difficult. In beginning more than 2 month pass but TBM advanced only 2 meters. It is 1 tunnel segment ring. Reason is ground. Ground is very sticky mudstone formation. TBM started working and TBM Cutter head cutters moved in mud cup. No advancement. China Railway 14th Bureau Group experts met in many meetings. They found solutions. Changes in slurry circulation treatment. Changes in cutters, buckets. Seven tool changing positions. Solutions work. Today advancement is 10 meters in average each day.  Every 2 meters, after each tunnel segment ring specialized worker enter between mud body and cutter head to clear the mud inside. It is work in pressurized place. Liucun TBM is Earth Pressure Balance TBM. Very important TBM always moves. It is heavy 3000 tons. If it stops ground subsidence can occur. Maybe TBM may sink in mudstone formation. For comfort of residents China Railway 14th Bureau Group spent 4 million yuan in noise reduction systems. Now noise is in 6q-64 decibel.