Characteristic functions of regional soils: concepts and principles

As the starting point of the theoretical study on the regional soil characteristics, based on the classical theories of soil mechanics and soil dynamics and the actual data, the related concept, principle, criterion and demonstration are put forward. Based on the classical constitutive model for soils, the concept of dual-control parameter is proposed, which is a basis for the theoretical study on the regional soil characteristics. The concept of regional soil characteristic function is put forward, its definition, connotation and extension are clarified, and the construction criteria including control, universality, completeness, in situ, consistency, operability and existence are put forward. For the conventional sand and clay, the idea of using $N{\text{ - }}{v_{\text{s}}}$ characteristic function to characterize its regional soil characteristics is proposed, the construction method is given, and its principle is clarified. The existence of $N{\text{ - }}{v_{\text{s}}}$ characteristic function of sand and clay is proved by analyzing the distribution characteristics of N-v_s function relations in 77 regions of 17 countries of the world.