Question

You are tasked with designing shallow foundation for a commercial structure that will be constructed on ALLUVIAL SAND deposits from an ancient lake bed. What important geotechnical information do you need in order to recommend an allowable bearing pressure for the design and ideally, how would you obtain in? Think about what calculations, and input values you would need to make recommendations. Hint: I recommend you simply use bullet points under two columns with the headings “what” and “how”.

Answer 1

Important geo-technical information needed to recommend an 'Alluvial Sand' sample for foundation construction and methods to obtain them will be:

1. Soil composition - Using sieve analysis

2. Drainage - Percolation test

3. Organic Matter content - Walkley-Black acid digestion method or weight loss on ignition method

Based on above tests, if the alluvial contents of the soil are very high, then it won't be good for construction. In that case, either we have to go for raft foundations or pile foundations. Or else we've to excavate the soil to a significant depth.