Experimental Investigation on Mass Loss Characteristics of Broken Rocks with Discontinuous Gradation

Abstract

This study mainly focuses on the transport process of broken rocks in geological fractures, faults, and karst conduits. Because previous research mainly focused on the influencing factors of adverse geological conditions, there is no clear understanding of the migration behavior of fillings and the formation process of pathways in the process of water inrush. An experimental testing apparatus was designed and developed to perform systematic research on the transport process of granular soils subjected to seepage flow. This system was comprised of a water supply system, acrylic glass holding device, and collection system, which could effectively be used to study the influence of discontinuous gradation and flow velocity on the permeability characteristics of loosening fillings. The experimental results show that the water inrush induced by seepage failure results from the gradual migration and loss of particles by water seepage. According to the fine-grain content and loss characteristics of the samples, the samples are divided into three types: those with a nonskeleton structure, with a dense-suspension structure, and with a void-skeleton structure. With an increase in the content of fine particles, the porosity and permeability decrease whereas the time required for water inrush of the sample gradually increases. With an increase in flow velocity, the time required for water inrush and its rate of change gradually decrease. However, the mass loss of particles does not increase with the increasing flow velocity during the same period. The research results provide a valuable reference with which to further study the mechanism of variable mass seepage in faulted and fractured rock.