Guidelines for Managing Geotechnical Risks in Design–Build Projects (2018) / Chapter Skim
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From page 57... ...
B-1 This appendix contains the templates of the forms and spreadsheets described in the guidelines. The blank spreadsheets are also available for download from TRB's website at www.trb.org by searching on NCHRP Research Report 884.
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B-2 Guidelines for Managing Geotechnical Risks in Design–Build Projects Very High 5 (I)
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Site / Ground Hazard Potential Impact Before Control Comments and Proposed Mitigation Risk RatingConditions L I R Co nt am in ati on U nd er gr ou nd V oi ds Previous site use Contaminated materials and groundwater Health and safety, environmental damage, pollution requiring remediation Mine shafts Shaft collapse Surface deformation, structural damage; health and safety Shallow mining Working tunnel collapse, sink holes, subsidence Surface deformation, structural damage Deep mining Tunnel consolidation, subsidence Surface deformation Natural cavities; solution features Unstable natural ground; sink holes Surface deformation, structural damage; health and safety Other voids; basements, sumps, tanks, wells, and adits, etc. Collapse, subsidence Surface deformation, structural damage; health and safety Sl op es a nd E ar th w or ks Existing steep slopes on site Slope failure Site stability; surface deformation at crest, structural damage to services, highways and property Gradient on site Earthworks or retaining walls required to accommodate layout Increased cost As-dug cut material unsuitable as fill Unstable earthworks Surface deformation, structural damage Embankment stability Slope failure Site stability; surface deformation at crest, structural damage to utility services, highways and adjoining property Cut stability Slope failure Health and safety Insufficient suitable fill Import required to achieve design levels Increased cost of development Fo un da ti on s & Su bs tr uc tu re s Loose or soft, compressible soils at shallow depth Ground unsuitable for conventional shallow footings or supporting embankments and structures Excess settlement or alternative foundations Adjacent structures Works on site affecting stability of adjacent structures Alternative design or altered development layout Differential settlement Differential settlements beneath embankments could affect design geometry Damage to the track resulting in remedial works being necessary Aggressive ground chemistry Attack of buried concrete Protection required Table B.1.
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Condition Hazard Impact L I R Comment / Mitigation RR Sl ab s an d Pa ve m en ts Soft and compressible near surface soil Ground unsuitable for conventional groundbearing slab Alternative slab design Soft and compressible near surface soil Low California bearing ratio due to soft formation Surface damage or alternative design Frost susceptible soils Frost heave Surface damage or alternative design D ra in ag e & F lo od in g High permeability strata Ineffective storm water attenuation ponds/water and environmental Ponds need lining if required to retain water Low permeability strata Ineffective permeability Alternative drainage required High groundwater Effects planned works construction and final levels. Alternative vertical alignment/plateau levels required affecting cut fill balance feasibility Embankment earthworks and cutting slopes will require drainage Insufficient attenuation permeability and retention ponds to accommodate earthworks drainage Flooding Local watercourse Flooding Flood protection required Loose or unstable Excavation instability Collapse or support required; health and safetystrata at shallow depth Hard strata/ Hard digging/hard Increased cost and delay obstructions at driving shallow depth Presence of unrecorded sensitive underground services.
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GEOTECHNICAL RISK REGISTER PROJECT # AFTER APPLIED STRATEGY RISK PROGRESS Date APPROACH TO RISK RESIDUAL RISK ASSESSMENT RISK EXPOSURE (Milestones)
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Geotechnical Design Decision Register Decision Milestones Category No. Design Package Key Decision Associated Risk Alternatives Considered Activity Early Start Date Activity Late Finish Date Decision Milestone Date Remarks General Concern Utility Environmental Geotechnical Construction Table B.3.
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Geotechnical Risk Management Plan Project Phase Strategy Risk # Geotechnical/ Subsurface Risk Risk Exposure Date Exposure Passed Date Expected Retired Date Pre-advertising Procurement Pre-construction Construction Geotechnical Risk Mitigation Tool Assigned to Risk 1 Early Contractor Involvement 2 Early Third Party Involvement 3 Increase Visibility of Geotechnical Issues 4 Enhanced Contract Mechanisms 5 Life Cycle Decision Making Table B.4. Geotechnical risk management plan.
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