Correlation between the rock mass properties and maximum horizontal stress: A case study of overcoring stress measurements

Understanding the mechanical properties of the lithologies is crucial to accurately determine the horizontal stress magnitude. To investigate the correlation between the rock mass properties and maximum horizontal stress, the three-dimensional (3D) stress tensors at 89 measuring points determined using an improved overcoring technique in nine mines in China were adopted, a newly defined characteristic parameter C_ERP was proposed as an indicator for evaluating the structural properties of rock masses, and a fuzzy relation matrix was established using the information distribution method. The results indicate that both the vertical stress and horizontal stress exhibit a good linear growth relationship with depth. There is no remarkable correlation between the elastic modulus, Poisson’s ratio and depth, and the distribution of data points is scattered and messy. Moreover, there is no obvious relationship between the rock quality designation (RQD) and depth. The maximum horizontal stress σ_H is a function of rock properties, showing a certain linear relationship with the C_ERP at the same depth. In addition, the overall change trend of σ_H determined by the established fuzzy identification method is to increase with the increase of C_ERP. The fuzzy identification method also demonstrates a relatively detailed local relationship between σ_H and C_ERP, and the predicted curve rises in a fluctuating way, which is in accord well with the measured stress data.