Holdfast Training Services Trial Blog

At what point in an engineers career is he able to look at a problem and sense that risks haven’t properly been addressed…?

The risk in question here is safe. More specifically, slope stability of the excavation below. The slope is at a 1:1 batter at a height of 5m. The bund at the top of the slope (RHS) indicates the outer edge of the proposed site haul road (not yet operational), which will carry all laden plant. The bottom of the slope is ready for a piling mat for abutment piles. From this, I would suggest a surcharge of 20kPa at the top of the slope. The profile and design borehole is estimated below in the sketch.

Strength properties have been taken from the principal contractor’s temporary works (TW) team for other designs. If is interesting to note that most TW problems to which the site team having varying opinions

The approach/opinion to this has varied dramatically on site. The opinions are: 1) “It will be fine”, 2) “This needs assessing by TW”,  3) This is unsafe”. All project managers (10+ years experience) and all with civil engineering degrees.

What is your gut reaction? for this problem? for other problems? What problems can you rely on your heuristics to address the risks?

Experience is critical but training goes a long way.

My personal opinion (without analysis) is a suitable assessment with either GEO5 and Bishop’s method is required to propose a technical solution and manage risk. Furthermore, I would need to do some re-reading of the rock classification and discontinuities to determine if this is unsafe. I would feel semi-comfortable on doing some analysis on this and making the call on site without TW design. Perhaps a feature of a TMR in the future.