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The conceptual hydrological model represented by the ABCD model is one of the main methods to quantify and analyze the hydrological cycle processes. However, few studies have examined the physical basis of the variables and parameters of the ABCD model and quantified the relationship between parameters in the conceptual hydrological model and traditional soil hydraulic parameters. In this study, we select the Taigemiao mining area in the Ordos basin as the research site. The HYDRUS-1D software is used to construct the soil-plant-atmosphere continuum (SPAC) model at a site scale for obtaining the “real” actual evapotranspiration during the non-freezing period. The actual evapotranspiration obtained from the SPAC model is considered as the objective function of the ABCD model for calibrating the ABCD model. The soil water storage and soil water leakage simulated by the ABCD model are compared with the results of the SPAC model. The relationships between the parameters of a and b in the ABCD model and the traditional soil hydraulic parameters are analyzed through a large number of scenario simulations. The results show that the ABCD model can better simulate the site-scale monthly actual evapotranspiration and soil water leakage during the non-freezing period. It is indicated that parameter a in the ABCD model has a strong linear correlation with the saturated water content, residual water content and curve shape parameters, while it shows a negative logarithmic relation to the saturated coefficient of permeability. It is also found that parameter b has a strong linear correlation with the saturated water content and curve shape parameter n, while the logarithmic relationships is revealed between parameter b and the saturated coefficient of permeability and curve shape parameter α. This study can improve the understanding of the physical basis of variables and parameters in conceptual hydrological models, and expands the application of hydrological models to hydrogeology.

Anodization is performed on the Ti-30Zr-5Al-3V (TZ30) alloy to improve its surface performance. X-ray diffractometer (XRD), scanning electron microscopy (SEM), and Olympus microscope are used to determine the phase constitution, morphology, and thickness of the anodization film (AOF). Tribological tests and electrochemical corrosion experiments are carried out to measure, respectively, the wear behavior and corrosion resistance of AOFs in simulated body fluid (SBF) solution. The microstructure characteristic of the AOF anodized at low voltage (20 V) is composed of compact and loose regions. As the applied voltage increases to 60 V, the compact regions transform progressively into loose regions, and then grow into nanotube regions. Besides, an increase in thickness of the AOF from 8.6 ± 4.61 μm to 20.7 ± 2.18 μm, and a gradual increase in surface microhardness from 364.6 ± 14.4 HV to 818.4 ± 19.3 HV, are also exhibited as the applied voltage increases from 20 V to 60 V. Specimens anodized at 40 V and 60 V have a low friction coefficient (~0.15) and wear rate (~2.2 mg/N/m) in the SBF solution. The enhanced wearability originates from the high hardness and various wear mechanisms. Potentiodynamic polarization curves suggest that the corrosion resistance in the SBF solution of all anodized specimens is greatly improved, thanks to the protection from the anodized TiO2 film.

In order to solve the problems of low hardness and poor wear resistance of titanium alloy, laser cladding technology was used to prepare Ti(C,B)/Ni coatings with different amount of Cr3C2 on the surface of Ti-6Al-4V titanium alloy. The effects of Cr3C2 content on the microstructure, hardness and wear resistance of Ti(C,B)/Ni coating were investigated by methods of scanning electron microscope (SEM), x-ray diffractometer (XRD), microhardness tester and M-200 wear tester. The results showed that phases existing in coating mainly contain γ-Ni, Ni3Ti, NiTi, TiB2, Ti(C,B) and CrB. With the increase of Cr3C2 content, the size and number of black bulk precipitates in the coating reduced. Meanwhile, the short rod-like Ti(C,B) particles grew and the amount of the particles increased, and Ti(C,B) particles existed in the form of cellular dendritic crystals in the coating. The average microhardness of the cladding layer without Cr3C2 addition is 896.7 HV0.2, which is about 1.5 times higher than that of Ti-6Al-4V substrate (360 HV0.2). With the increase of Cr3C2 content (10, 20, 30 wt.%), the average microhardness of the coating increased to 948.7, 990.4 and 1035.8 HV0.2, respectively. The average hardness of the coating added 30 wt.%Cr3C2 is 15.5% higher than that of the Cr3C2-free coating. At the same time, the wear resistance increased with the increase of Cr3C2 content. [ABSTRACT FROM AUTHOR]

Groundwater is the main source of water in the grassland in eastern China, this region is one of the largest coal bases in China. It is of great significance to study the influence of opencast coal mine exploitation on the chemical characteristics of groundwater in grassland and thus to evaluate the suitability of irrigation water based on changes in the chemical characteristics of water. To study the background values of the chemical characteristics of groundwater and thus to assess the effects of high-intensity coal mine exploitation on groundwater, the water samples in this study were obtained from the mining site, as well as from private wells and rivers. It is found that the dominant hydrochemical types of the local surface water and groundwater are the Ca2+-Mg2+-HCO3– and Na+-Cl– types. The concentrations of Na+, HCO3– and SO42– are relatively high in these water samples, and nearly all of them exceed those in the WHO and GB 5749-2006 standards. Both the shallow aquifer water and surface water samples exhibit high salinity, low and moderate alkalinity, and low conductivity, which indicates that they can be used for irrigation. However, the quality of the deep groundwater samples is Permissible to Doubtful, and the coal seam aquifer water is not suitable for irrigation due to its high salinity, high alkalinity and high conductivity. To guarantee the safe usage of domestic and irrigation water, mine drainage is an important alternative to alleviate the local water usage contradiction. The post-processing drainage of coal seam aquifers should be fully taken into consideration. A groundwater monitoring network around the mining area, including urban areas, should be established and improved. The coal seam aquifer water source should be adequately avoided during future well drilling. [ABSTRACT FROM AUTHOR]

The exploitation of coal resources can lead to change of regional environment, and open-pit mining makes even more direct impact on vegetation, topsoil, surface water and underground water in grass area. Studying the change of hydrogeological condition caused by open-pit mining is beneficial for rational utilization of water resource in grass area and guaranteeing normal exploitation of open-pit mine. In this study, the Shengli 1 open-pit coal mine with typical hydrogeographical features, locating in typical meadow steppe area, was taken as researched area. Through collecting basic mine production data, such as annual output, drainage quantity, water inflow, the water inflow (including static- storage and recharge rate) of mine was predicted and calculated by horizontal catchment channel method, big well method and replenishment quantity method, respectively. This study investigates the hydrogeological condition changes of open-pit coal mine in grass area during production process. Results show that the static storage of hydrogeological unit exerts great impact to coal mine exploitation and production in early stage, while recharge rate exerts continuous influence to the whole mining process. As the quarternary loess in earth surface of steppe area is thick, and phreatic layer has a direct association with mining pit, the replenishment quantity method can achieve the most accurate calculation; the influence of open-pit mining to geohydrologic condition is mainly determined by aquifer hydraulic conductivity and mining depth. [ABSTRACT FROM AUTHOR]

To identify the lithology of coal seam roof and explore the influence of these roofs on the enrichment of coalbed methane, low-frequency rock petrophysics experiments, seismic analyses and gas-bearing trend analyses were performed. The results show that the sound wave propagation speed in rock at seismic frequencies was lower than that at ultrasound frequencies. Additionally, the P-wave velocities of gritstone, fine sandstone, argillaceous siltstone and mudstone were 1,651 m/s, 2,840 m/s, 3,191 m/s and 4,214 m/s, respectively. The surface properties of the coal seam roofs were extracted through 3D seismic wave impedance inversion. The theoretical P-wave impedance was calculated after the tested P-wave velocity was determined. By matching the theoretical P-wave impedance of the four types of rocks with that of the coal seam roofs, we identified the lithology of the roofs. By analyzing known borehole data, we found that the identified lithology was consistent with that revealed by the data. By comparing and analyzing the coal seam roof lithology and the gas-bearing trends in the study area, we discovered that the coal seam roof lithology was related to the enrichment of coalbed methane. In the study area, areas with high gas contents mainly coincided with roof zones composed of mudstone and argillaceous siltstone, and those with low gas contents were mainly associated with fine sandstone roof areas. Thus, highly compact areas of coal seam roof are favorable for the formation and preservation of coalbed methane. [ABSTRACT FROM AUTHOR]