CONVERSION RATE

摘要

In the mountains northwest of Mexico City, the soft rock is self-supporting and very consolidated, a dream to mine. "Even the face is self-supporting," says Roberto Gonzalez, Robbins' general manager in Mexico. "You could use a normal backhoe and excavate like that. It's a beautiful ground to bore." But the alignment crosses valleys of tuff, faults and finishes with a stretch of soft ground with low cover. This is the scenario for Tunel Emisor Poniente Ⅱ (TEP Ⅱ), or the English translation of West Drainage Tunnel Ⅱ. Conagua, Mexico's national water commission, is building the 5.9km-long tunnel with a 7m i.d. to reduce flooding in the area, and increase wastewater capacity. Across three municipalities, some 2.1 million people will benefit from the tunnel project. The contractor joint venture of Aldesa, Proacon and Recsa chose an 8.7m diameter, dual-mode type machine capable of "crossing over" between rock and EPB. With the August 2015 TBM launch on TEP Ⅱ, manufacturer Robbins has supplied its first Crossover machine in Mexico.