Experimental and Numerical Investigation on Group Anchor Performance of Wooden Bolts in Rammed Earthen Sites

Challenges remain in understanding the interaction mechanisms and influencing factors of multi-anchor systems. To investigate this matter, this study conducted nine full-scale model experiments examining the pulling resistance and failure modes of wood bolts embedded in rammed earth. These experiments varied bolt numbers (2, 3, 4), spacings (500 mm, 1000 mm, 1500 mm), and embedment depths (200 mm, 300 mm, 400 mm). Key factors and their levels for the group anchoring effect in the model tests were determined through orthogonal analysis. Among these factors, embedment depth exerted the most significant influence on pulling resistance, followed by bolt spacing and number. Furthermore, a numerical simulation method for wooden anchor group systems was developed using the "contact surface" element in FLAC 3D finite difference simulation software. This method considered factors such as bolt number, spacing, edges, embedment depth, and the layered nature of the compacted soil. It analyzed stress distribution and transmission laws across various interfaces within the anchoring system and the compacted soil, thereby supplementing and expanding upon the findings of the model experiments. These findings enhance understanding of the complex interplay between multi-anchor systems and soil, providing a scientific foundation for analyzing mechanical behavior in similar anchoring applications.