On May 8, 2020, the first CRCHI Hard Rock TBM for the East China region broke through at the first phase of Zhuxi Reservoir Project in Taizhou city after it drove about 5 km.
This Hard Rock TBM is 295 m long, weighs over 800 t, has an installed capacity of 2,400 kW and a 17 km-long belt conveyor. The TBM began its trial tunnelling on May 31, 2019 and finished boring to ensure top quality and safety. It achieved a national record of 51.61 m in one day and 1001.76 m in a month.
The tunnel section using TBM construction method was 15.95 km, with an excavation diameter of 4.03 m. The biggest burial depth was 800 m, longitudinal gradient was 1.5‰ and the rock with compressive strength ranging from 150 MPa to 200 MPa accounted for 58%, over 200 MPa 22%. That is, TBM construction faced difficulties including long distance of boring, small excavation diameter and high rock strength. Therefore, how to ensure high durability and reliability of TBM and its spare parts became the most challenging part for the project.
To solve these problems, the cutterhead of this TBM was specially designed to be suitable for the complicated geological conditions and an advanced geological prediction system was fitted to effectively improve safety of construction. In addition, the TBM has high adaptability as it integrates many functions like excavation, muck discharge, support, grouting, ventilation, dust removal, material transportation and guidance.