Exploring the Root–Soil Anchoring Dynamics of Bambusa pachinensis (Pachi Bamboo) Root System

Bamboo is widely distributed throughout the world, particularly in tropical and subtropical regions. This study aims to investigate the biomechanical properties of the root system of Bambusa pachinensis (Pachi bamboo). The root system of Pachi bamboo grows densely in clusters, with most roots growing vertically and potentially penetrating more than one meter into the soil after growing for several years. Owing to these characteristics, Pachi bamboo is considered a promising plant species for soil reinforcement. However, research on its root reinforcement capabilities remains limited. In situ shear and pullout tests were conducted to assess the root reinforcement of the fibrous root system. The root diameters of Pachi bamboo are typically less than 4 mm, and its tensile strength is notably lower than that of tree roots. This study establishes a method for estimating the root reinforcement of Pachi bamboo based on the number and cross-sectional area of the culms in a single bamboo cluster. The relationship between the maximum tensile force (F_ult) and root diameter (D) is F_ult = (3.65)D^2.59, where F_ult is in Newtons (N), and D is in millimeters (mm). The relationship between the pullout resistance (P_ult) and the shear resistance (S_ult) with the number of culms (SN) is P_ult = 46.5(SN) and S_ult = 0.53(SN) + 5, where P_ult is in Newtons (N), and S_ult is in kilopascals (kPa). These results suggest a positive contribution of the number of culms to mechanical resistance.