SPECIAL MOBILITY STRAND The European Commission support for the - PowerPoint PPT Presentation

SPECIAL MOBILITY STRAND The European Commission support for the production of this publication does not constitute an endorsement of the contents which reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

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SITE CONDITIONS INFLUENCING ON GEOLOGICAL AND DIVISON WITH RATINGS COMMENTS GROUND UNCERTAINTY Simple Clear Complicated The distribution of rocks, 1 Geological setting 1) tectonic structures, foldings, 1 2 4 etc. Minor Moderate High The degree of weathering at the 2 Degree of rock rock surface, making weathering at terrain observations and interpretations 0.5 1 3 surface of the rocks at tunnel/cavern level more difficult. 3 Area of rock surface None or Moderate Comprehensive The rock cover reduces the covered 2) (by soil, minor possibilities to forecast the rock lake/sea, vegetation, mass conditions underground. 1 3 5 buildings, etc.) < 10 m / 10- Long distance from rock 50 – 300m > 300 m 50 m surface to the tunnel increases the uncertainties in forecasting 4 Rock overburden. the rock mass conditions. As Distance from excavation limited (low) rock cover (< 10 to rock surface 2 / 0.5 1 4 m) is a risk, a rating = 2 is suggested. The same rating is set to surface excavation. 1) after information from investigations 2) which has not been investigated SUM (∑) OF THE VALUES FROM EACH TOPIC Low: ∑ < 5 Medium: ∑ = 5 - 8 High: ∑ > 8 Degree of geological uncertainty

TYPE OF ISSUE TECHNICAL RELEVANCE GEOLOGICAL FACTOR Rock cover Damage of structures on ground Damage of third part Rock quality Ground water lowering Ground water pressure Pre and post grouting Rock mass permeability Environmental or social impact Vibration disturbance Attenuation by the rock mass Front stability Rock mass quality Initial rock stresses Workers safety Time until initial support has to be Geometry of geological installed structures Squeezing ground Time before permanent support can be Long term stability Swelling ground installed Raveling ground

RELATIVE ECONOMIC CONSEQUNCE CLASS CLASS EXAMPLE OR LOSSES LOSS TO PROJECT COST EN 1990:2002 1 < 0.1 % Negligible Small or negligible Minor costs due to construction 2 0.1 to 1 % mistakes Reparations costs for inadequate 3 1 to 10 % Considerable design Cost for reparation of local tunnel 4 10 to 100 % collapse Very great Rebuilding of the project due to 5 > 100 % malfunction

CONSEQUNCE CLASS CLASS FATALITY EXAMPLE OF PROJECT EN 1990:2002 1 No, in general Deep tunnels Low 2 < 1 Shallow tunnels in rural areas Shallow tunnels below parks, 3 1 to 10 Medium streets and roads Shallow tunnels bellow buildings 4 10 to 100 and crowded places High Shallow tunnels below residential 5 > 100 buildings

Work Shaft

Risk Example of actions to be applied against each class Classification The risk shall be reduced at least to Unwanted regardless of the Unacceptable costs of risk mitigation Risk mitigation measures shall be identified. The measures shall be implemented as long as the costs of the measures are not Unwanted disproportional with the risk reduction obtained (ALARP principle, a s l ow a s r easonably p racticable) The hazard shall be managed throughout the project. Acceptable Consideration of risk mitigation is not required Negligible No further consideration of the hazard is needed

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