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.
May 25, 2018
Manholes Module Delivers Measurement Capabilities, MACP Compliance and Online Results Sharing.
May 24, 2018
Spray in Place Pipe Solution is added to Vortex Companies’ Trenchless Offering.
May 23, 2018
Fluence Corporation Limited announced that it has received a contract to deliver a water treatment reuse system to its customer Rosenblad Design Group. Fluence’s zero liquid discharge (ZLD) solution will utilize ultrafiltration and reverse osmosis equipment to treat brine for ...
May 22, 2018
A convertible Herrenknecht multi-mode tunnel boring machine (TBM, Ø 9,890 mm) was used for the project to modernize the Czech railway line between Rokycany and Pilsen. The machine excavated two single-track tunnels, each about 4 km long. Because of the ...
May 21, 2018
Allied Environmental Services, Inc., one of the Great Lakes region’s premier environmental contracting firms, is reporting a stronger than expected first quarter aided by the growth of its industrial coatings and linings application services.
May 21, 2018
Trials of an advanced tertiary water and wastewater treatment system have proven its effectiveness in removing several trace substances from wastewater final effluent.
May 18, 2018
Second introduction to the wastewater treatment process video focuses on headworks.
May 17, 2018
Sterling Construction Company, Inc. announced that Myers & Sons Construction LLC, a consolidated affiliate, is the apparent low bidder on a $30 million Colorado Springs Utilities water treatment facility project in Colorado Springs, Colorado.
May 16, 2018
To escape the high youth unemployment in their homeland, seven young Spaniards began an apprenticeship as industrial mechanics at Herrenknecht in September 2014. All in all an exemplary success story! Six of the career starters successfully completed their dual vocational ...
May 15, 2018
Held in Dubai, from 21st to 26th April by the Society of Engineers (SOE) and the International Tunnelling and Underground Space Association (ITA), the World Tunnel Congress and 44th ITA General Assembly were a momentous occasion and an undoubted success ...
May 14, 2018
This year’s edition of the IFAT once again features a unique range of strategies and solutions to tackle diverse and complex global challenges such as waste and water management. Combining Hobas and Flowtite pipes under one roof for the first ...
May 14, 2018
ProMinent presents an particularly affordable approach to water treatment on Stand 451/550 in hall A3 at IFAT in Munich, from 14 to 18 May 2018: Chlorine gas disinfection with DULCO®Vaq. The new vacuum metering system for chlorine gas combines maximum ...