Abstract
Remarkable hydrostatic pressures have a significant effect on the failure mechanical properties of seafloor minerals, which also affects the selection and development of mining excavation tools. In this paper, a Brazilian splitting test and triaxial compression test were adopted to investigate the strength and deformation behavior of two kinds of seafloor massive sulfides (SMS) samples at a small-scale size. Based on the mineralogical characterization of the studied samples, the mechanical properties were preliminarily correlated with their internal structures and mineral compositions. Results indicate that there is a significant difference in the triaxial compression deformation properties between the two kinds of SMS samples and the geotechnical data are controlled by mineral type and composition, including porosity. In general, the triaxial compression process of the two kinds of samples included initial compaction, elastic stage, yield stage, failure stage and residual stage, and shows strain softening characteristics after the peak. With the increase in confining pressure, the strain-softening behavior of the white sample is mitigated and gradually changes into strain-hardening. The peak strength and peak strain of the two samples increased linearly with the increase in confining pressure within the confining pressure range of these tests, and the failure pattern of the specimens also changed from a typical brittle failure to a ductile failure. The results of this study provide data to support further understanding of different kinds of SMS, and are of great significance in the design of efficient SMS exploitation equipment.
Highlights
Marine minerals, such as manganese nodules, co-rich ferromanganese crusts, and seafloor massive sulfides, are generally regarded as potential resources that could have a significant impact on the international metal market [1,2]
The results showed that the peak strength of the raw coal and sandstone samples increased linearly with the increase in confining pressure
These studies were based on non-seafloor massive sulfides (SMS) materials and showed that a triaxial compression test is an effective means to understand mechanical properties, and confining pressure has a great impact on the mechanical and permeability characteristics of rocks, especially on strength and deformation behavior
Summary
Marine minerals, such as manganese nodules, co-rich ferromanganese crusts, and seafloor massive sulfides, are generally regarded as potential resources that could have a significant impact on the international metal market [1,2]. Su [17] and Xu [18] conducted triaxial compression tests on red sandstone and cemented tailings, respectively Their results showed that the strength parameters of rock under different stress environments are obviously different, and the deformation and failure characteristics change obviously. Wang [19] studied compressive strength and deformation under uniaxial and triaxial compression tests to investigate the mechanical properties of ultra-high strength concrete and ultra-high-performance concrete under various stress states These studies were based on non-SMS materials and showed that a triaxial compression test is an effective means to understand mechanical properties, and confining pressure has a great impact on the mechanical and permeability characteristics of rocks, especially on strength and deformation behavior. Posits, and especially for the development of seabed excavation equipment
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