There are many reasons a geotechnical engineer would recommend a deep foundation over a shallow foundation, but some of the common reasons are very large design loads, a poor soil at shallow depth, or site constraints (like property lines).
There are many reasons. A geotechnical engineer would recommend a deep foundation over a shallow foundation many reasons. Some of the common reasons are very large design loads. Very large design loads are a poor soil at shallow depth. Very large design loads are a poor soil at site constraints (like property lines).