A Method for Testing Rock Mass Elastic Modulus Based on Anchor Pullout Tests and Its Optimization

To achieve rapid and accurate acquisition of field parameters in underground and geotechnical engineering, this paper proposes a novel method for inverting the elastic modulus of rock mass based on anchor pullout tests. First, the main failure modes of the anchoring system during pullout are systematically analyzed, clarifying the characteristics of different failure mechanisms. Second, a theoretical model based on shear stress distribution is established, deriving the relationship between end load and end displacement under elastic conditions to provide a theoretical foundation for the inversion of the rock mass elastic modulus. On this basis, combined with actual field test data, a feedback correction technique integrating linear fitting and numerical simulation is employed to optimize the influence range parameters and improve the accuracy of the inverted results. Validation through multiple typical engineering cases shows that the deviation of the obtained rock mass elastic modulus generally falls within about 5.7% to 12.5%, demonstrating good practicality and reliability. The study also notes that, due to simplifications in considering material nonlinearities and plastic deformations, the model has certain limitations, and future work should incorporate more complex nonlinear material models for further improvements. This method offers an efficient and straightforward approach for rapid inversion of rock mass parameters, supporting safer and more precise engineering design in underground excavation, tunnel construction, and mining projects.