“I took the "undisturbed" sample from the pipe, put it into the cylinder, got its now moist weight, flooded the soil-filled cylinder, got its saturated weight, and then estimated its phi angle”
PEinc, I am wondering what is the base/theory for estimating the friction angle by this method. If the sample is below the river bed, it must be below the groundwater table anyway which means the in-situ condition is saturated. In this case, the weight of a clayey sample before and after flooding it should not change that much. In case of a sandy soil, it is a bit complicated as saturated sand may lose some water during sampling and extraction and then you get it back to saturation. In this case, the weight difference may mean something. However, it is complicated as you cannot say how much water the originally saturated sample may lose through the sampling process. On the other hand, I can understand if you let the sample dry first then measure the dry weight and then make it saturated, and measure the saturated weight. In this case, the weight difference for sandy soils provides a base for estimating the friction angle (may also applicable for clayey soil). I appreciate if you can help me to understand your method.