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Slope Stability - Open cut excavation

Slope Stability - Open cut excavation

Slope Stability - Open cut excavation

I have a foundation about 3m deep which I want to excavate open cut. I have space available around the excavation so do not need to add the expense of an earth support system. But how to calculate a safe angle for the stability of the excavated face. The excavation is in sand and I plan to use tarpaulin covers to give some erosion protection during the construction of the foundation.

RE: Slope Stability - Open cut excavation

to reduce your liability -

  • if you are going to follow minimum OSHA standards, then let the contractor specify the temporary cut slopes and let them design any necessary shoring.
  • if you (a registered engineer) are recommending temp cut slopes or shoring, then you need to follow the standard of care, which generally means you are a qualified geotechnical engineer

RE: Slope Stability - Open cut excavation

Read your OSHA excavation standard carefully as you could encounter different soil layers. A ratio of three (3) horizontal to one (1) vertical bears to mind for sand.

RE: Slope Stability - Open cut excavation

this is a type C soil according to OSHA 1926 Subpart P. maximum allowable slopes for excavations less than 20 feet deep are 1.5H:1V (34 degrees). slope length may be reduced by shoring or benching. slope angle may be decrease if their is groundwater or signs of slope distress. contractor's competent person should be the one making this call. alternatively, a qualified registered engineer can design slopes based on actual soil data.

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