Determining the parameters for the overlying stratum caving zones during re-peated mining of pillars

Abstract

Purpose. The research aims to determine the parameters for the overlying stratum caving zones above the mined-out space during repeated mining of pillars at the Zhomart Mine of the Zhaman-Aybat field for the purpose of predicting hazardous zones of influence of mining operations. Methods. Research includes an analysis of the results of previous in-situ studies conducted using seismic surveys, as well as modeling with the Examine2D software to determine the stress-strain state of the overlying stratum mass. The elastic and strength characteristics of an anisotropic mass are used for modeling, taking into account the generalized Hoek-Brown criterion with the Geological Strength Index (GSI) based on a geomechanical description of the mass quality. Comparative analysis of modeling results with seismic survey results is conducted to confirm the effectiveness of the developed methodology. Findings. The research provides an opportunity to determine the overlying stratum caving parameters, such as the caving arch height and the condition for complete undermining of the overlying stratum at the Zhaman-Aybat field at different spans of the mined-out space (from 50 to 350 with a step of 50 m, reaching the maximum span of 370 m). Originality. . It has been determined that the caving arch height depends on the outcrop span and increases exponentially (hcav = 16.473 e0.008Le). In addition, the condition of the earth’s surface complete undermining has been identified depending on the depth of the site to be gotten. Practical implications.The research results can be used to develop a normative document for calculating the earth’s surface shear during the repeated mining of pillars at the Zhomart Mine of the Zhaman-Aybat field. The data obtained will also be useful in planning repeated mining and predicting the earth’s surface shear to avoid negative impacts of mining operations on surface structures.