# Earth Pressure \[PIG] Earth-pressure loads in OpenBrIM model the horizontal pressure exerted by retained soil or a live-load surcharge on abutment back walls and the footings they rest on. The Abutment Earth Pressure library object converts an active earth-pressure coefficient and backfill unit weight into a triangular (earth pressure) or uniform (live-load surcharge) surface load that is applied to the selected abutment at a chosen construction stage. For a detailed explanation of each library object, refer to the relevant section of the documentation. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.openbrim.org/templates/precast-i-girder-bridge-workflow/loading-pig/loads-pig/earth-pressure-pig.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.