基坑一般用固结不排水试验，如果现场取土回来，土的重度为20，3M深，室内试验为什么还要固结一下呢，是不是围压要加到 20乘3=60kpa，模拟这个竖向压力，否则试验室固结一下，意义是什么，谢谢

if you fetch the soil sample from the field, the soil has experienced a stress releasing process, in that situation, the soil is not in NC condition (for NC soil) any more