Recently presented at Intermat in Paris and already successfully carrying out work for the metro expansion in Milan, Liebherr’s new package for slurry wall applications is comprised of a duty cycle crawler crane and hydraulic grab.

The hydraulic slurry wall grab is modularly designed and has an extremely robust base body. As the names imply, HSG 5-18 C and HSG 5-18 L can install slurry walls with thicknesses between 500 and 1,800 mm, depending on the composition. The “C” stands for the compact standard design, while the base body of the “L” version is 2.5 m longer. The resulting total height of the grab (9.5 m) and the high weight with low center of gravity provide for even better vertical positioning and are especially advantageous when installing larger dimension slurry walls. When working in difficult ground conditions, the execution can be improved through increasing the dead weight of the grab with an additional weight of 7 t.

The heavy weight of the grab is viable thanks to the proven synchronization of the free-fall winches. This means the lifting capacity of the duty cycle crawler crane is optimally utilized. The slurry wall package can be adapted to the conditions on the jobsite, and diesel consumption is only 25 liters per hour. The robust construction of the grab is designed for unrestricted use and a long service life. Although part of the slurry wall package, the duty cycle crawler crane is multifunctional and can, for example, be quickly converted for chisel applications or operation as a lifting crane.

Also, a sensor from Jean Lutz SA can be optionally fitted on the grab, which measures the vertical positioning in x, y and z directions. Data is transferred from the sensor to the control system via Bluetooth. The current verticality of the bite and any possible deviations are displayed on the monitor in the operator’s cab. Using Liebherr’s process data recording PDE, all data are electronically logged, displayed and recorded.

Opened in 1964, the “Metropolitana di Milano” is scheduled to be expanded by 2022 with the new line M4. The 15 km long route, with 21 stations between San Cristoforo and Linate Aeroporto, is being executed over a period of seven years. The company, SAOS s.r.l., is currently installing slurry walls for the new stations in the central section of the jobsite at San Babila. For this work, they are relying on the duty cycle crawler crane HS 8100 HD with hydraulic slurry wall grab HSG 5-18 L.

While international crowds stroll through the Italian metropolis, the extremely confined space at the Piazza San Babila is a major challenge for the construction work. In this section, SAOS is installing 6,300 m² of slurry walls for the metro extension. At 130 m² per day, the Liebherr package has displayed its high productivity. In San Babila, SAOS are excavating bites of 2,800 x 1,200 mm with depths of up to 54 m. Layers of gravel, sand and loam have to be penetrated. One bite requires 16 hours, whereby half of the time is dedicated for excavating. The reinforcement is inserted and concrete is filled. During the execution of the work for the new M4 line, SAOS has to install slurry walls totaling 84,000 m². According to Liebherr, SAOA has been extremely satisfied so far with, and, moreover, emphasizes the flexibility and reliability, of the HS 8100 HD. “The Liebherr package is designed so that we can work to our full capacity,” Rossi Fabio, assistant manager from SAOS, says.