Revisiting the assessment of squeezing condition and energy absorption of flexible supports: A mine development case

Abstract A vast majority of assessment methods for squeezing condition are generally based on empirical studies. The empirical studies rely on the existence of the case data and when the database is expanded, the existing studies can be revised accordingly. In this research, 35 data points were collected from mine development openings with a large depth range and variable support systems were considered to modify pre-existing squeezing condition assessment methods. Together with the chart modifications, new equations were proposed by linear multiple regression method to predict the convergence of the underground openings. The ratio of support pressure to vertical stress was the major parameter for the modifications. Another contribution is the involvement of support energy absorption which was calculated based on support pressure and the radial displacement of the support. The energy to be absorbed by the support systems was correlated with depth, strength and rock mass classification ratings. It must be noted that the energy absorption is pronounceable for flexible or yielding supports and not for rigid or heavy support systems. The limitations and shortcomings of the modifications and new approaches are also provided.