SCHOOL OF CIVIL ENGINEERING Presented by: Jonathon Simons Sanjo Adeyemo Taiwo Oshodi An Investigation into the Geological Faults and Subsequent Construction Implications

SCHOOL OF CIVIL ENGINEERING Introduction to the Project Geological Conditions The Collapse Causes of Failure The Solutions Conclusions

SCHOOL OF CIVIL ENGINEERING Lane Cove Tunnel Collapse Sydney Australia Connecting the M2 Freeway at North Ryde to Gore Hill Freeway AU$1.1billion contract Awarded to Theiss & John Holland Joint Venture Source – Google Maps Data 2010

SCHOOL OF CIVIL ENGINEERING The Collapse Occurred on the 2 nd November 2005 The first collapse occurred at approx 01:40 am 02:00 am a hole was observed approximately 4-5m wide and had undermined approximately 1-2m under the road 06:00 am, a secondary collapse was heard and the hole had widened to approximately 8-9m

SCHOOL OF CIVIL ENGINEERING Dangerously the hole compromised the stability of a neighbouring tower block Damage to the unit block at Longueville Road, Lane Cove Source – Work Cover: New South Wales

SCHOOL OF CIVIL ENGINEERING 1. Geological conditions at the site 2. The large span width of the tunnel intersection 3. The proximity of the tunnel excavations to the ground surface 4. The nature of the tunnel roof support installations

SCHOOL OF CIVIL ENGINEERING Hawkesbury Sandstone & Ashfield Shale Lane Cove Tunnel lies predominately in the low strength Shale Site Engineer classed the bedrock as having low to very low strength The Presence of a (doleritic) Dyke Rock Mass Joints and Faults

SCHOOL OF CIVIL ENGINEERING Longueville Road retaining wall Rock Bolting Inadequate support system Advancement of one side of the tunnel to quick Specifications not adequate for region of tunnel

SCHOOL OF CIVIL ENGINEERING The tower block was evacuated and the road closed at 06:45 The hole was then filled with concrete and then the voids filled with grout to finalise the stabilization Approximately 2750 cubic metres of concrete and grout were pumped into the collapsed area

SCHOOL OF CIVIL ENGINEERING The Solution Pacific Highway Off- Ramp at south western corner of Kerslake Apartments. Void backfilling with concrete 3rd November 2005 Source – Work Cover: New South Wales

SCHOOL OF CIVIL ENGINEERING New foundations using piles Diverting the tunnel

SCHOOL OF CIVIL ENGINEERING Low Strength Shale Presence of dyke Jointing Failure Retaining wall drilling Poor rock stabilizing methods Rock bolting not installed to specification causing failure of the ground support system

SCHOOL OF CIVIL ENGINEERING