Tunnel Boring
The Dead Sea Power Project proposes the use of three tunnel boring machines (TBM) of the double shield design to bore a ten meter inside diameter tunnel of approximately 72 kilometers length. The prefabricated concrete segmented tunnel lining will be installed and grouted inside the TBM shield. Opening a truck ramp down to tunnel level near Mevo Horon will enable the use of the three TBMs, One starting from each end of the tunnel, and one introduced at the midpoint ramp opening.
Tunnel Boring Machine efficiencies and capabilities have been tremendously increased in the last fifteen years, and the possibilities today are greatly different from those that existed in the seventies and eighties when the old plan for a Mediterranean Sea-Dead Sea canal and tunnel project was proposed and abandoned because of political and economic concerns. Today, according to the most experienced tunnel boring experts, it is possible to build a segmented concrete lined tunnel of ten meter inside diameter from Palmahim to the reservoir site for approximately one billion US dollars. This estimate of the cost and construction method for the Ezekiel's Water Project tunnel was prepared by a leading senior tunnel design engineer. This estimate agrees with two other estimates, that the tunnel can be constructed within five years at a cost of one to one and one half billion US dollars.
Tunnel Estimate
TBM for Guadarrama
"Guadarrama
It could not get any more exciting than what Spain has arranged for the completion of this 26.7 km long high-speed railway through the Sierra de Guadarrama: a racetrack through the mountains, where two competing TBM manufacturers can demonstrate to the international market who is ahead in TBM technology and service. Both, Herrenknecht and Wirth, will supply two Double Shield Machines (Æ 9.51 m). Each manufacturer will place one of its boring machines at the north portal of the two parallel tunnels, its second machine at the south portal of the other tunnel. Once excavation begins, the two sets of opposing machines will race towards each other, having until the middle of the mountain to prove who has the better team, TBM concept and service."
Source: http://www.herrenknecht.de/en
Double Shield TBMs - For projects with difficult ground that still demand the speed of a Main Beam TBM
"Fractured rock can be an insurmountable obstacle if you buy the wrong machine. Your crew safety and efficiency is at risk, and so is your schedule. With a Robbins Double Shield Tunnel Boring Machine (TBM), your project can have a great safety record and peak performance.
Robbins is no stranger to this type of TBM design. In fact, this is another type of TBM we invented! In 1972 Robbins built the world's first Double Shield TBM for a customer who anticipated tunneling through large sections of fractured rock. In recent years, several Robbins Double Shield TBMs have broken world records for production.
TBM Estimate: _link to letter_____________
Source: http://www.robbinstbm.com/
TBM - Mitsubishi Heavy Industries
In recent years, an integration of tunneling technology is demanded to cope with boulder-containing layers soil and rock miexd layers and other complicated tunneling condition. We have developed TBMs shown here, integrating technologies of shield machines and hard rock TBMs.
Leading tunnel boring machine manufacturers are:
Herrenknecht AG
Robbins Company
Wirth-Europe
Mitsubishi Heavy Industries