Classification Identification of Acoustic Emission Signals from Underground Metal Mine Rock by ICIMF Classifier

To overcome the drawback that fuzzy classifier was sensitive to noises and outliers, Mamdani fuzzy classifier based on improved chaos immune algorithm was developed, in which bilateral Gaussian membership function parameters were set as constraint conditions and the indexes of fuzzy classification effectiveness and number of correct samples of fuzzy classification as the subgoal of fitness function. Moreover, Iris database was used for simulation experiment, classification, and recognition of acoustic emission signals and interference signals from stope wall rock of underground metal mines. The results showed that Mamdani fuzzy classifier based on improved chaos immune algorithm could effectively improve the prediction accuracy of classification of data sets with noises and outliers and the classification accuracy of acoustic emission signal and interference signal from stope wall rock of underground metal mines was 90.00%. It was obvious that the improved chaos immune Mamdani fuzzy (ICIMF) classifier was useful for accurate diagnosis of acoustic emission signal and interference signal from stope wall rock of underground metal mines

Three-dimensional Information Acquisition and Visualization Application in Goaf

AbstractMastering the shape, size and variation of goaf is important to goaf disposal, disaster control and mining optimization. A method is presented to realize goaf precision monitoring and 3D visualization by cavity monitoring system (CMS). On this basis, Goaf 3D modeling, goaf-model visualization transmission and display based on network, visible calculation method of mining loss and ore dilution during actual mining, 3D blasting design of complicated boundary pillar during actual mining, dynamic monitoring of goaf, stability analysis of tunnel above goaf, 3D survey and analysis of tunnel destruction caused by goaf collapse, numerical simulation of goaf stability and all other related technologies are researched and applied by using numerical software and network. Results showed that 3D space information of goaf could be accurately acquired by CMS, and visualization application based on the information is reliable. These research and application are of great practical significance to recover mineral resources and assure safe mining

Mechanical Properties of Rock With Intersection Structures and its Progressive Failure Mechanism

To investigate the influence of intersection structures on the mechanical properties and failure mechanisms of rock materials, a series of uniaxial compression tests on complete red sandstone specimens and specimens with various hole shapes (T-shape, cross-shape, and shaft-roadway-shape) were conducted by the Instron 1346 servo-controlled rock mechanics testing machine. Flac3D software and digital image correlation (DIC) were used to simulate the internal stress distribution of rock specimens and reproduce the process of fracture, i.e., cracks initiate, propagate, and coalesce with each other into macroscopic failure under progressive loading. The results show that the intersection structure has a signiflcant weakening effect on the mechanical properties of the rock. The rock strength, elastic modulus, and peak strain of specimens can be ranked as complete specimens > cross-shaped intersection structure specimens > T-shaped intersection structure specimens>shaft-roadway-shaped intersection structure specimens. The energy consumption ratio of the intersection structure specimens before the peak reaches more than 30%, which is approximately twice that of the intact specimens. The brittleness coefflcients of the four types of specimens are 0.18, 0.26, 0.21, and 0.20, respectively. The intersection structure specimens induced different degrees of tensile and compressive stress concentration zones on the top and bottom sides of the intersection center point. As a result, initial tensile cracks parallel to the loading direction and shear cracks leading to spalling failure on both sides of the holes were formed. With the increase of the axial stress, secondary tensile cracks extending on the opposite direction appeared at the upper and lower corners of the hole. When the far-fleld cracks that propagated along the diagonal line coalesced with secondary tensile cracks, macro shear-failure of the specimens appeared. With the increase in axial stress, the principal strain monitored during the fracture process of the specimens gradually increased, then it slowly decreased after the peak. The arched boundary of the T-shaped intersection structure specimen had good stability because of its advantage of suppressing the occurrence of the spalling failure. The shaft-roadway-shaped intersection structure could provide compensation space for the secondary tensile cracks due to the existence of the vertical well. The degree of inhibition of initial tensile cracks was so small that the type of specimens was highly prone to instability or failure.National Key Research and Development Program of China during the Thirteenth Five Year Plan Period: The Continuous Mining Theory and Technology on Spatiotemporal Synergism of Multi-mining Areas within a Large Ore Block for Deep Metal Deposit [2017YFC0602901]; Fundamental Research Funds for the Central Universities of Central South University [2018zzts215]Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Rock mechanics parameters

Rock mechanics parameters for simulation in the paper

Data from: Plastic limit bearing calculation of blasting-roof in deep hole mining and its applications

In order to solve the problem that blasting-roof thickness was hard to determine in deep hole mining, the plastic bearing calculation method of blasting-roof was proposed. Aim at typical boundary conditions of blasting-roof, mechanical analysis model of plastic bearing was built. The external work and internal work of blasting-roof under plastic limit state were calculated. Based on virtual work principle, the limit bearing formulas of blasting-roof under various boundary conditions were derived. Taking a VCR stope as the object, the safe blasting-roof thickness was determined as 6m by derived formula (considering safety coefficient). Numerical model of stope was constructed by Surpac-Flac3D technique, while blasting-roof stability was simulated under different thickness. The variation of simulated indexes (stress, plastic zone volume) prove that theoretical calculation is reliable. The plastic bearing calculation method can provide a new way for determining blasting-roof thickness in deep hole mining

Effect of Incorporating Waste Limestone Powder into Solid Waste Cemented Paste Backfill Material

To effectively reuse waste limestone powder, which is a major solid waste around mines, we replaced limestone powder back into a part of cement in solid waste cemented paste backfill (SWCPB) and studied the parameters of pore structures. To optimize the pore microstructure characteristics of SWCPB in mines, two different components and grade tailings were selected. The samples were characterized by scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR) to examine the pore properties and microstructure of SWCPB. The results showed that (1) at the later curing stage, with the optimization of pore characteristics and microstructure through the limestone powder admixture, the strength of SWCFB was guaranteed at a 20% replacement degree of cement. (2) Porosity, macropore proportion, and the average pore radius all negatively correlated with limestone powder content, which were reduced by 7.15%, 46.35%, and 16.37%, respectively. (3) Limestone powder as a crystal nucleus participated in the hydration reaction and was embedded into the product to enhance the strength

Data from: Plastic limit bearing calculation of blasting-roof in deep hole mining and its applications

In order to solve the problem that blasting-roof thickness was hard to determine in deep hole mining, the plastic bearing calculation method of blasting-roof was proposed. Aim at typical boundary conditions of blasting-roof, mechanical analysis model of plastic bearing was built. The external work and internal work of blasting-roof under plastic limit state were calculated. Based on virtual work principle, the limit bearing formulas of blasting-roof under various boundary conditions were derived. Taking a VCR stope as the object, the safe blasting-roof thickness was determined as 6m by derived formula (considering safety coefficient). Numerical model of stope was constructed by Surpac-Flac3D technique, while blasting-roof stability was simulated under different thickness. The variation of simulated indexes (stress, plastic zone volume) prove that theoretical calculation is reliable. The plastic bearing calculation method can provide a new way for determining blasting-roof thickness in deep hole mining

Multiphysics Coupling Model of Rock Mass considering Damage and Disturbance and Its Application

Aiming at the deficiency of the conventional multiphysics coupling model, the deterioration of strength parameters was considered by defining elastoplastic damage variables, and the heterogeneity of strength parameters was expressed by the Weibull distribution function. In addition, the relation between effective stress and the anisotropic permeability matrix was established, and the blast was transformed into a load boundary condition. On this basis, an improved multiphysics coupling model that considered damage and disturbance was constructed, while a corresponding finite element calculation program was developed. Taking an excavation stope as the object, the characteristics of the mining-induced stress, seepage, and failure were analyzed by an improved multiphysics coupling model and compared with actual detection data. The results show that the improved model reflects the extent and range of mining-induced failure more accurately and fits well with the actual detection. These results are compared to the conventional multiphysics coupling model and a single physics model. It is indicated that the improved multiphysics coupling model and corresponding calculation program are effective and rational