I've been able to conduct a moisture content analysis. My question is this.... the soil sample is wet, how do I go about grain size distribution analysis?
Your question of doing this yourself would mean that you need the tools for doing the tests. Usually the sample has to be dried first. A typical soils laboratory has, among other things: oven, small containers, good precision scales, sieves of varying size openings, dispersion chemical, standard model dispersion machine, Hydrometer and cylinder, instruction manual. A wet sample may have to be used that way with hydrometer test to avoid the effect of drying, but also sieves may be needed for a dry sample. If you are not so equipped or have not been so trained, send the samples to someone that does, as recommended above. This is really just doing standard tests.
First off, really, all, the OP should go find himself an elementary text on soil mechanics and read - typically chapter 1 or 2, about soils, their properties and how to measure. I found myself scratching my head in that the OP knows there is such a thing as a particle size distribution but can't figure out how to do it? What he has not noted is whether the material is a clay or sand - but it might be amorphous peat or fibrous peat in which case the particle size distibution is rather dubious to begin with.
As BigH noted, get a soils lab book...Lambe and Whitman, Bowles, etc. Read ASTM D422 and follow the procedure. You will need a full nest of sieves, a mechanical sieve shaker, a wash-200 sieve, an oven and a scale accurate to at least 0.01g with a range of up to about 1500g.
Better than that....pay a local geotechnical lab to do the test at a nominal fee (less than $100) and you'll get a grain size distribution curve and other classification info. You'll spend more than $100 just thinking about it!
I would like to say. Determine Moisture content and then follow the Procedure ASTM D422
if there is more silt or Clay you head to Atterburg Limits to know the soil classification properly.
