Freyssinet soil protection solution at Mumbai Metro Line 3 Project

Under the framework of Metro Line 3, Package 5 underground stations in Mumbai Vidyanagari, BKC and Sahar Road, Freyssinet Menard India was awarded the works related to the soil protection during underground excavation within the dense urban area.

Excavation and Lateral Support (ELS) has been a very important and prominent process in underground metro construction projects that involve deep excavation. The traditional steel struts support to the retaining walls during excavation, however, has imposed several limitations to the contractors both in terms of space and time. One practical solution is the use of the removable temporary ground anchor system. In fact, the temporary removable anchors have several advantages over the traditional method, which are:

• Creating a clear internal working space for better manoeuvre of plants and machinery.
• Allowing the flexibility of mobilisation of larger output plants.
• Unrestricted excavation brings about saving to valuable construction time to meet tight construction programme.
• Reducing the construction cost of installation of large temporary steel members and kingposts.

As per the recommendation from the engineer and ease of construction, Freyssinet Menard India carried out temporary retractable inclined cable anchors (60MT & 80MT capacity) and GFRP anchors (60MT capacity) and executed successfully for J Kumar Infraprojects (main contractor) using Freyssinet innovative technology and high QHSE system. Freyssinet is proud to state that all installed cables have been removed in a triumphant manner (100% installed cables are removed from others property) after completion of excavation work.

The adoption of temporary removal ground anchors provides both a cost-effective and site efficient solution to the job. Due to the large unbalanced lateral soil load, ground anchor system has been used instead of mega shoring system. This method also provides very good working space for piling work. The removable ground anchor system also provides a solution where there may be a land occupation issue with a third party.

The Freyssinet system has been used extensively and successfully throughout the world. This system could be adopted in different retaining structures, varies from the sheet pile walls to a deep diaphragm wall, and it also could be adopted in slope stabilizing project and any other application that the company plans to develop.