Apr 20, 2018
Workhorse Machine makes progress in Difficult Ground.
The cavern, studded with stalactites and stalagmites and measuring 8,000 cubic meters (283,000 cubic ft) in size, was grazed on the tunneling operation’s left side. The crew named the cavern “grotte Marie Lesimple” after their site geologist.
“We hit the corner of it. To cross it, we had to erect a 4 m (13 ft) high wall of concrete so the TBM would have something to grip against,” explained Marc Dhiersat, Project Director of Galerie des Janots for Eiffage. A small door allowed access inside the cavity, which formed naturally at a point 60 m (200 ft) below the surface. The TBM was started up and was able to successfully navigate out of the cavern in eight strokes without significant downtime to the operation.
“This is certainly unusual, to come across a cavern of this size and significance. It is somewhat related to the geology, with karstic and volcanic formations having the most potential for underground cavities,” said Detlef Jordan, Robbins Sales Manager Europe. Karst cavities were a known risk during the bore, but the cavern was not shown in vertical borehole reports conducted from the surface along the alignment.
A further 1.8 km (1.1 mi) will need to be tunneled before the 2.8 km (1.7 mi) tunnel is complete. “It is possible there could be more unknown caverns. We have a geotechnical BEAM system on the machine, and are conducting probe drilling, shotcreting, and maintenance in a separate shift,” said Dhiersat. The BEAM system, standing for Bore-tunneling Electrical Ahead Monitoring, is a ground prediction technique using focused electricity-induced polarization to detect anomalies ahead of the TBM.
The crew encountered difficult ground conditions early on in the bore, consisting of limestone with powdery clays. “When the machine is boring it does well. We have good production and it’s a good machine for hard rock. But sometimes it’s not hard rock that we encounter,” said Dhiersat.
The weak rock and clay conditions necessitated ground support including resin-anchored bolts and rings in bad ground, topped with a 10 to 15 cm (4 to 6 in) thick layer of shotcrete. Despite five months of poor ground conditions, Eiffage is optimistic that conditions will improve and the tunnel will be complete in the next four to five months.
The completed tunnel will pass under Le Parc National des Calanques, with cover between 15 and 180 meters (50 to 600 ft), in order to replace the pipes that are currently being utilized for the water supply networks. “The current pipes have a capacity of transit limited to 330 liters (87 gallons) per second, which is largely insufficient in the summer period. The objective of the operation is to secure the lines and increase capacity to 440 liters (116 gallons) per second,” said Dhiersat.
Oct 17, 2018
The potential of sensors and digital technologies to transform the water sector was in the spotlight at a British Water conference took place in Leeds on 3 October 2018.
Oct 16, 2018
REHAU acquires MB Barter & Trading.
Oct 15, 2018
Evoqua Water Technologies Corp. announced it has completed an exclusive sales and distribution agreement with Horizon Solutions, LLC (“Horizon”) to expand local service in Puerto Rico.
Oct 12, 2018
Tsurumi has developed a new pump solution for overhauling sewers and pipe systems that allows the pipes to continue operating whilst work is being carried out.
Oct 11, 2018
Get the Inspection Crawler Wheel Set-ups Poster.
Oct 10, 2018
Massive XRE Machine breaks through at Akron OCIT.
Oct 09, 2018
Herrenknecht AG welcomes Federal Minister of Economic Affairs and Energy Peter Altmaier at its Schwanau plant. On Tuesday, company founder and Chairman of the Board of Management Dr.-Ing. E.h. Martin Herrenknecht familiarized the Minister with the company and the global ...
Oct 08, 2018
The National Association of Water Companies (NAWC) applauds the reintroduction of the “Sustainable Water Infrastructure Investment Act” (S. 3358) by Senators Bob Menendez (D-NJ) and Mike Crapo (R-ID).
Oct 05, 2018
BWinnovate matches utility needs and supply chain solutions: The detailed searches help identify most appropriate technologies. The new portal is open to the worldwide web and includes videos and images.
Oct 04, 2018
The benefits of Ingevity’s AquaNuchar powdered activated carbon for municipal water needs are being highlighted in a recently released video about a North Carolina-based water authority who’s able to exceed some of the U.S. Environmental Protection Agency’s requirements regulating byproducts ...
Oct 03, 2018
Cured-In-Place Pipe Liner Provides Seamless and Structural Restoration Over Major Waterway.
Oct 02, 2018
Woolpert was contracted by the city of South Bend, Ind., to implement the Cityworks Asset Management System (AMS) for the Department of Public Works’ Office of Sewers.