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Salt rock, mudstone, and glauberite are three typical rocks of the salt cavern gas storage. In order to obtain the rocks’ characteristic parameters of acoustic emission under the stretching test, the Brazilian split test and acoustic emission test were carried out. The results show that among the three rocks, salt rock’s strength is the lowest, with peak stress of 1.27 MPa, which is less than 1/2 of mudstone and slightly lower than glauberite. The maximum strain salt rock corresponding to the peak stress is 0.007 6, which is 1.5 times larger than mudstone and more than 2 times that of glauberite. Among the three rocks, the maximum number of acoustic emission events for salt rock is 10 148, mudstone is 119, and glauberite is 1 166. The salt rock first appears the acoustic emission event point at the cushion, while the mudstone and glauberite appears in the middle part of the sample and extended towards both ends along the loading direction. The energy rate and the ringing count rate of three rocks increases significantly during the yield deformation stage. The cumulative energy and cumulative ringing count of the salt rock rose in the form of a smooth curve, which the curve of the mudstone is stepped, and the glauberite is steep near the peak stress. The maximum average energy and ringing count of salt rock is 2.02×10-14 J and 1 200.6 times. Mudstone is similar to glauberite, of which difference between salt rock is large. [ABSTRACT FROM AUTHOR]

The failure process of the open-pored T300/1034-C carbon fiber composite laminate with a ply angle of [ 00 I ( ± 45°) /3 ( 90° ) 3]s under tensile load was studied by using 2-D shell elements and 3-D solid elements in the ABAQUS finite element software. First, the shell element and continuous shell element carbon fiber composite material models were established with the ABAQUS finite element software, and the internal failure of the layer was simulated using the built-in 2-D Hashin criterion and degradation model. However, the 2-D model did not consider the interaction between the failures of each layer, and by writing the material subroutine VUMAT, the 3-D Hashin criterion and the equivalent stress-strain bilinear degradation method based on the fracture energy were introduced, and the solid element was used to simulate the carbon fiber composite material failure behavior. Through the simulation of three element models, the results showed that the stress concentration caused by the opening will make the fiber and matrix of the laminate more likely to fail during the stretching process and become the source of cracks; during the failure process of laminates, they all show a failure development trend from " X-shape" to "hourglass-shape", and eventually break in the width direction; compared with the traditional shell element and continuous shell element, the simulation accuracy of the solid model is closer to the experimental value. The simulation limit failure loads of the three elements differ from the literature data by 26. 1%, 31. 1%, and 8. 64%, respectively. [ABSTRACT FROM AUTHOR]

In view of problem of floor heave failure in coal seam roadway, taking 53082 roadway of a mine as the research object, the stress state, displacement distribution and failure form of surrounding rock during the roadway excavation were analyzed and studied by UDEC discrete element simulation software. The results show that under relatively large horizontal tectonic stress, the weak coal seam of roadway floor 53082 becomes the main area of stress release, and the main failure characteristics are shallow tensile failure and deep shear failure. In view of problem that the original support scheme of roadway 53082 can not control the floor displacement and causes serious floor heave, a combined support mode of floor grouting and anchor bolt and cable was put forward through simulation analysis of support effect of different floor support schemes. The test results show that the combined support mode of floor grouting and anchor bolt and cable is superior to the single support mode of anchor bolt and cable, and greatly improves stress state of floor, and restrains the shear failure of deep floor, the displacement of roof and floor is controlled within 150 mm, the displacement of two sides is controlled within 60 mm, and the control effect of surrounding rock of roadway is better.

Copyright of Journal of Engineering Geology / Gongcheng Dizhi Xuebao is the property of Journal of Engineering Geology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The safety assessment of PBX explosive is inseparable from the characterization of its mechanical response and damage. In order to accurately capture the mechanical behavior of PBX explosive, the numerical characterization method of PBX explosive mechanical behavior is studied based on Karagozian& Case (K&C) model framework. The damage evolution mode in the K&C model is modified, and the pressure-dependent characteristics of PBX explosive modulus and damage evolution mode are considered. Based on a series of published experimental data, the strain rate effect in the K&C model was corrected, the ratio of tension to compression meridian of PBX under different pressures was discussed, the deformation localization in the process of structural damage was dealt with, and the treatment of the tensile failure unit in the calculation was presented. The proposed model can be used to well depict the cratering morphology of explosive specimen in the Steven test, and successfully capture the tensile and shear failure images of explosive specimen. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Mine Automation is the property of Industry & Mine Automation Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to study the feature extraction and recognition method of fibers' tensile failure, AE technology is used to collect AE signals of fiber bundle's tensile fracture of two kinds of fibers of Aramid 1313 and viscose. A transform called wavelet is used to deal with the signals to reduce noise. A method called Hilbert-Huang transform (HHT) is used to extract characteristic frequencies of the signals after the noise is reduced. And a classification method called Least Squares support vector machines (LSSVM) is used for the classification and recognition of characteristic frequencies of the two kinds of fibers. The results show that wavelet de-noise method can reduce some noise of the signals. Hilbert spectrum can reflect fracture circumstances of the two kinds of fibers in the time dimension to some extent. Characteristic frequencies' extraction can be done from marginal spectrum. The LSSVM can be used for the classification and recognition of characteristic frequencies. The recognition rates of Aramid 1313 and viscose reach 40%, 80% respectively, and the total recognition rate reaches 60%.

Copyright of Journal of Hebei University of Science & Technology is the property of Hebei University of Science & Technology, Journal of Hebei University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)