TUNNELLING IMPACTS | TECHNICAL


Conservative assumptions


Assessment scope Limits of deviation STAGE 1 Location?


Information retrieval


Material? Size? Condition?


Consequence of damage?


Geo-environment? Type? R&M History? Criticality?


Current state of strain?


Exclusion zone? Maximum curvature


settlement contour


Green field


Curvature?


More detailed analysis


conservative assumptions


Green field analysis Transverse analysis STAGE 2 Vulnerability?


Health & Safety issues?


Consequence of failures?


Financial impacts?


Statutory or commercial obligations?


Strain? Middle-third rule? Moderately


Longitudinal analysis


Strain? Distortion? Pullout? CPR?


Joint rotation?


ALARP Concept


Risk/remedy- based approach


diversionary/ mitigation works?


STAGE 3


Consequential losses (H&S/Statutory Requirements/ Commercial)?


Uncertainties & Difficulties


Soil-structure analysis?


Corroboration (closed-form solutions/case history data)


Need for


Risk to life and/or other third parties?


Inconvenience to public?


H&S risk to work around utilities?


Network resilience?


Retain whole life asset value?


serviceability? Maintain


Do nothing & repair when required?


(Developer & Utility)


Collaboration


Incorrect analysis/ human errors


Further considerations Type? Location?


interpretation method?


Frequency? Data


Trigger level?


Monitoring, control & validation


Action plan? Mitigation


Pre & Post work inspection?


RAMS Package Review of Diversion? serviceability?


Do minimum to maintain


Preparedness Plan?


Emergency Strengthening? Replacement?


Above, figure 18: Summary of staged assessment process


February 2022 | 29


Asset not eliminated by Stage 1 assessment


Asset fails to meet the assessment criteria, or high criticality/vulnerable asset


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