The coal dust disaster is serious in deep mining of coal mine. The use of nonionic surfactant can effectively improve the wettability of coal dust and inhibit the generation and diffusion of coal dust. In order to explore the wetting process and mechanism of different surfactants on coal dust surface, the effects of nonionic surfactants lauryl glucoside (APG) and Triton X–100 on the wettability of coal dust surface were studied by molecular dynamics simulation and experiment. Three coal–water interface adsorption system models were established based on benzene ring carbon skeleton structure. Analysis the adsorption equilibrium configurations and spatial distribution of the surfactant on surface of coal were calculated on the basis of the interaction energy between coal/surfactant/water and energy changes, looked at the two kinds of surfactants and the ability of water molecules to form hydrogen bond. The coal samples from three groups of coal seams in Pingdingshan mining area in Henan Province were tested, the experiments of sedimentation and contact angle were carried out, and the surface free energy composition of the coal samples was calculated. The simulation results were verified, the characteristics of aromatic hydrocarbon groups in the coal samples and the interaction mechanism between Triton X–100 and coal molecules were tested by Fourier infrared spectroscopy (FT–IR). The results showed that when the adsorption equilibrium state is reached, the non-ionic surfactant molecules are connected with each other through alkyl chains to form an aggregation state, which is distributed at the coal water interface and the water gas interface. Triton X–100 can promote the adsorption of water molecules on the coal surface by enhancing the interaction with water molecules, which has a great impact on the wettability of the coal surface. The indoor test results showed that the wetting effect of Triton X–100 on the coal surface is better than APG, and the effect is the best at the critical micelle concentration. The higher the content of aromatic hydrocarbons in coal dust, the better the adsorption of Triton X–100. The research results provided a theoretical support and guidance for scientific and efficient dust suppression in deep mining

Alkali-resistant glass fiber has good mechanical performance, economy and durability. By adding alkali-resistant glass fiber, cement-based composites can be well strengthened, which has a wide range of engineering application prospects. To study the compressive properties and the stress–strain relationship of alkali-resistant glass fiber engineered cementitious composites (ECC), 33 groups of high-performance cement-based material specimens were tested under axial load. The effects of fiber content, fiber length, and water-cement ratio on the compressive properties and stress–strain relationship of alkali-resistant glass fiber ECC were emphatically analyzed, and the calculation model for the stress–strain relationship of alkali-resistant glass fiber ECC was proposed. The results show that the crack resistance, mechanical property, and deformation capacity of cement-based materials can be significantly improved by adding alkali-resistant glass fiber under uniaxial compression. The improvement of compressive strength and deformation capacity of the alkali-resistant glass fiber ECC is related to the fiber content, fiber length, and water-cement ratio. The compressive strength and deformation capacity of alkali-resistant glass fiber ECC specimens roughly tend to increase with the increase of fiber content and length, but the compressive strength of specimens decreases due to the obvious “agglomeration” phenomenon when the fiber content is too much. The compressive strength of specimens is mainly affected by the water-cement ratio, and it exhibits smaller with a larger water-cement ratio. When the fiber mass content is 6.5%, the fiber length is 18 mm and the water-cement ratio is 0.32, the comprehensive mechanical properties of alkali-resistant glass fiber ECC are relatively better, and compared with the comparison specimens, the compressive strength and deformation capacity can be increased by 25.6% and 88.0%, respectively. The calculation results of the proposed stress–strain relationship model are in good agreement with the experimental values, which can be used to describe the whole process of compression failure of alkali-resistant glass fiber ECC.

To investigate the damage mechanism of the thick coating in the steel frames under earthquake, one small-scale experiment was conducted. The failure modes and positions of the thick coating in the steel beam and columns were observed in detail. The inter-story displacement angle, beam, and column strain of steel frame structure under earthquake were obtained, and the relationship between inter-story displacement angle, strain, and the failure of the coating was analyzed. Based on the software ABAQUS, the elastoplastic damage model was used to predict the damage and fell-off behavior of the coating. In addition, the fell off and the failure mechanism of the thick coating in one steel column reported by the literature and the beam, column, and connection of the present steel frame were analyzed, and a comparison between the theoretical and experimental results was conducted. Results showed that the coating fell off on the web of the beam and the column did not occur, and it easily occurred on the beam-column connection, particularly near the connection region and the top flange of the beam. According to the strains of beam and column under earthquake, it was found that the position beyond the steel yield strain was corresponding to the part where the coating falls off. The Numerical results showed that the steel strain exceeded the yield strain or the inter-story drift ratio exceeded 1/150, and the coating fell off often occurred. Therefore, the elastoplastic damage model can reasonably predict the thick coating falling off. Meanwhile, the coating equivalent plastic strain distribution, the fell off position and the steel equivalent plastic strain conformed to the Mises stress distribution. In other words, larger steel equivalent strain and the Mises stress easily led to the coating fell off. It was found that the coating equivalent strain has an important effect on its fell off, and the thick coating effective plastic failure strain 0.002 could be used in the numerical analysis. In all, the presented results can be used in the coating design of the large-span steel frame, and thus it has a larger engineering application value

In recent years, deep learning-based methods have shown excellent performance in the field of image restoration. However, most deep networks are structured based on experience, and less consideration is given to fusion with existing traditional algorithms, therefore these networks arepoorly interpretable. To address this problem, an image restoration algorithm based on wavelet domain ADMM deep networkwasproposed. Firstly, a wavelet transform is introduced to the data term as well as the prior term simultaneously, an image recovery model under wavelet domain was proposed. Consequently the image recovery problem was transformed from spatial domain into wavelet domain, and a new image degradation model and recovery cost function were constructed. Then, in order to effectively reduce the difficulty of the optimal solution, the ADMM algorithm was introduced to further decompose it into a more manageable restoration subproblem and a denoising subproblem, and obtain the best estimate of the wavelet domain image through continuous optimization. Finally, the specific form of the solution based on the above optimization process guides the construction of a deep convolutional neural network to achieve end-to-end image recovery. The perceptual field and spatial feature mappingsizeof this networkis increased and decreased respectivelysince the image processing was executed in the wavelet domain. Not only does it achieve better performance, but also significantly reduces the complexity of operations and increases the processing speed. The proposed network was applied to image deblurring and image denoising tasks to verify the recovery performance on Set10, BSD68 and Urban100 datasets. The relevant experimental results show that the proposed algorithm achieves better recovery results for both deblurring and denoising tasks, with an increase of 0.08~0.18 dB in PSNR values while the resultant images retain more detailed information, thus outperforming the comparison methods in both quantitative and qualitative results

The mechanical properties of the soil-structure interface have always been one of the key and hot issues in the field of geotechnical engineering, and revealing its mechanism is helpful to promote the understanding of the bearing characteristic of structures such as pile foundations and retaining walls. A total of 28 groups of large direct shear tests with the post-grouting sand–concrete interface were conducted under three different grout volumes and four kinds of loading and unloading conditions to analyze the interface mechanical properties and the distribution of shearing influence range. The test results show that grouting can gradually eliminate the difference between the interface’s initial shear modulus and shear stress due to the loading and unloading of the interface. The softening phenomenon doesn’t exist in the un-grouted interface, while the post-grouting interface exhibits softening and the softening occurs in the unloading interface shearing process with low applied normal stress. The grout cement improves the mechanical properties of the interface by increasing the equivalent cohesive force of the interface but has no significant effect on the equivalent internal friction angle of the interface. The improvement of the interface equivalent cohesive force on the loading interface is better than the unloading interface under the same grout volume. The distribution of interface shearing influence range under unloading conditions is slightly larger than that under the loading conditions. Regardless of the loading, unloading, and grouting conditions, the distribution of interface shearing influence range is positively correlated with the interface peak shear stress. Under the same applied normal stress, the mechanical properties of the unloading post-grouting interface were improved due to the formation of the grout bulb by compaction grouting to increase the roughness of the concrete plate, while the mechanical properties of the loading post-grouting interface were improved by penetration grouting to form the soil-cement mixture. The research results can provide guidance for the post-grouting of pile foundations in practical projects.