Analytical model for pullout behavior of root system

Abstract

The pullout resistance is significant to protect slopes from tensive rainfall and strong wind. Explaining the pullout behavior of a root system is challenging because the root mechanical and architectural characteristics are difficult to characterize. This study proposes a new simplified analytical model of the pullout behavior with displacement. The root system is divided into several topological levels along depth, and then the parameter of the root diameter and root number distribution at each topological level is summarized respectively according to the test result. Mechanical characteristics are expressed as functions of the root diameter. The pullout force of the whole system is the sum of the force of every root segment. Then, the expression is verified by the result of field test, and its parameters are summarized. The influence of these parameters on pullout behavior is discussed. The model is also compared with other models: (1) a detailed analysis of the root architecture; (2) considering the root angle; (3) allowing the pullout force to deviate from roots. However, (1) the model needs more parameters; (2) the model can be improved by more consideration of the interaction between roots and soil. The model can be used in stability analysis, which should be researched.