Tunnelling shield

protective structure used in the excavation of tunnels through soil that is too soft or fluid to remain stable during the time that it takes to line the

excavating-machinery-industry-2016-global-trend-profit-and-key-manufacturers-analysis-reportExcavating Machinery Industry 2016: Global Trend, Profit, and Key Manufacturers Analysis Report
from AkshayKalla, ago in
For More info@https://goo.gl/0BmlDo Global Excavating Machinery Industry 2016 Market Research Report provides major statistics on the state of the industry and is a valuable source of guidance and direction for companies and individuals interested in the market.

Pipe and Excavation Contracting
Dave Roberts, published 1987, 400 pages