Mechanism and control of multi-level floor heave in soft rock roadway with straight-wall semicircular arch section

Abstract

Floor heave is a typical form of roadway damage in underground mining, often causing transportation and ventilation issues, as well as restricted access. While shear-induced slip is universally acknowledged as the predominant failure mode in roadway surrounding rock, existing research has not recognized the mechanism from the perspective of full-range surrounding rock movement source identification and main slip zone control, resulting in a lack of scientific basis for selecting support types and parameters. Therefore, failures in controlling floor heave are frequently reported, with severe cases exhibiting complete roadway closure due to fully uplifted strata. To achieve precise control of roadway floor heave, a high-resolution Flac^3D numerical model incorporating stress-release simulation technology, borehole imaging, and multi-layer compressive arch theory was employed. The initiation and evolution of floor heave were successfully reconstructed, with the morphology and location of the main slip zone as well as the surrounding rock structure being accurately characterized. In contrast to conventional control theories, this study presents the following key findings: The slip displacement in the main slip zone is identified innovatively as the critical control target. By suppressing the slip of the main slip zone, the formation of the multi-layer compressive arch is promoted, and thereby the stability of the comprehensive surrounding rock can be achieved. This study provides an accurate calculation method for the location of the main slip, which can more effectively guide the selection of the support systems and parameters. The proposed method was successfully validated in the 11,500 belt conveyor roadway of Shanghaimiao Coal Mine, Inner Mongolia, China. This control strategy represents a leap from empirical to precision-based floor heave management, establishing a new paradigm in roadway stability control.