“暗绿色硬土层”(以下简称“硬土层”)是上海地区大型和重型工程桩基础的主要持力层。随着“四化”建设的蓬勃发展,在工程勘察中发现,在硬土层之上局部存在与之性状相近的土层,但工作中常将其混为硬土而导致工程失误。为了提高工程勘 “Dark green hard soil layer” (hereinafter referred to as “hard soil layer”) is the main bearing layer for large and heavy engineering pile foundations in Shanghai. With the vigorous development of the “four modernizations” construction, it has been found during engineering surveys that soil layers with similar properties exist locally on top of hard soils, but they are often mixed in hard work and cause engineering errors. To improve engineering survey