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The Jurassic coal field in northern Shaanxi Province is generally threatened by roof water damage, so it is vital to study the law of overburden failure for mine safety production. Taking Yuandatan Coal Mine as an example, the development height of “two zones” in overlying rock of 11201 first working face of 2# coal seam was analyzed and studied through the observation of the loss of flushing fluid in the ground borehole and the field measurement of water pressure test, combined with numerical simulation and similar material simulation. The results show that based on the results of various methods, the development height of the water-conducting fracture zone in the roof of the 11201 first mining face of 2# coal seam in Yuandatan Coal Mine is determined to be about 104.36-110.37 m, and the fracturing ratio is about 32.61-34.49 times calculated according to the mining height of 3.2 m. Through the analysis and evaluation of roof water damage, it is considered that the mining of 2# coal seam is not directly affected by the overlying Cretaceous Luohe Formation aquifer, Quaternary aquifer and surface water, and the future roof water prevention and control work should mainly drain Jurassic Yan’an and Zhiluo formations aquifer water within the development range of overlying rock water-conducting fracture zone.

In order to solve the problem of No. 2 coal seam water hazards during the roadway tunneling process of the water-rich coal seam in northern Yuheng Mining Area, taking Balasu Coal Mine as an example, and combining the previous mining experience, firstly, the advanced drilling engineering （short drill + long drill） and the hydrochemical analysis in the rock roadway are carried out, and then the drainage water exploration ideas for the tunneling of the special coal seam water hazards in this area is proposed. The results show that the water drainage effect of the drilling project of No.2 coal seam in the early stage is remarkable, and the water volume and water pressure attenuation of each drill hole are obvious, indicating that the water recharge condition of No.2 coal seam is poor, and the whole coal seam belongs to the state of static water occurrence. Through the full analysis test of coal seam water, it is found that the water quality type of No.2 coal seam is basically SO4-Na·（Ｃａ） type water, with the pH value between 7.63-8.04 and a total salinity of 5 820.88 mg/L to 6 202.99 mg/L. It is believed that the water runoff and discharge conditions are limited and the water is in a closed state for a long time, which is conducive to the development of water drainage. Therefore, the ideas of drainage water exploration suitable for the roadway tunneling of No.2 coal seam in this area is proposed, including drilling technical schemes such as “double funnel mode”, “advance screen mode”, “lower coal drainagemode” and “bilateral feather mode”.

The over-exploitation of groundwater and the deterioration of its quality have heightened the importance of non-traditional water resources, such as mine water. The study of the water's chemical characteristics and the formation mechanism of high-salinity mine water in semi-arid regions holds significant importance for zero discharge and the resource utilization of mine water in Northwest China. In this study, a total of 38 groundwater and mine water samples were collected to examine the hydrogeochemical characteristics of high-salinity mine water using Piper diagrams and Gibbs diagrams, as well as isotope analyses and ion ratio coefficients. Additionally, the corresponding mine water treatment recommendations were put forward. The results show that the TDS content of groundwater increases with hydrographic depth. The average TDS concentration of Quaternary, Luohe, and Anding groundwater is 336.87, 308.67, and 556.29 mg/L, respectively. However, the TDS concentration of Zhiluo groundwater and mine water is 2768.57 and 3826.40 mg/L, respectively, which belong to high-salinity water. The Quaternary, Luohe, and Anding groundwater hydrochemical type is predominantly HCO3-Ca type, and the Zhiluo groundwater and mine water hydrochemical type is predominantly the SO4-Na type. Furthermore, there is minimal difference observed in δD and δ18O values among these waters. It can be inferred that the Zhiluo Formation in groundwater serves as the primary source of mine water supply, primarily influenced by the processes of concentration caused by evaporation. The high salinity of mine water is closely related to the high salinity of Zhiluo groundwater. The high salinity of groundwater has evolved gradually under the control of the concentration caused by evaporation and rock-weathering processes. The dissolution of salt rock, gypsum, along with other minerals, serves as the material basis for high-salinity groundwater formation. In addition, the evolution of major ions is also affected by cation exchange. The TDS concentration of mine water ranges from 3435.4 mg/L to 4414.3 mg/L, and the combined treatment process of nanofiltration and reverse osmosis can be selected to remove the salt. After treatment, mine water can be used for productive, domestic, and ecological demands. [ABSTRACT FROM AUTHOR]

Taking 3200 working face of Tianzhu Coal Mine as an example, by analyzing the geological and hydrogeological conditions of the mine, the main water filling source and water filling channel of the mining face are determined. Combined with the measured results of previous surface movement deformation, the surface collapse caused by mining 3200 working face was predicted, so as to judge the degree of surface rivers affected by mining. The results show that the sandstone aquifer of the Jurassic Xinhe Formation, the aquifer of the weathered oxidation zone, the Quaternary loose layer and the surface river are the main filling water sources after the mining 3200 working face. The main water-filling channels are the water flowing fractured zone and the closed bad borehole. After mining, surface collapse and deformation, Jinsha River will pose a threat to the working face incision within the range of 0-300 m. Combined with the actual situation on the site, this paper proposes some protection measures of water prevention and control for the working face before and after the mining process.

In order to solve the problem that the surface subsidence coefficient of shallow buried coal seam is difficult to determine in northern Shaanxi mining area, the data of surface rock displacement parameters in coal seam mining under different topographic conditions are collected in this paper. On the basis of analysis, three main influencing factors affecting the surface subsidence coefficient of the mining area are obtained, that is the ratio of bedrock thickness and overburden thickness JZ, the ratio of bedrock thickness and mining height JC, slope stability G. In addition to, taking JZ and JC as independent variables and combining topographic forms with piecewise function, the expression of surface subsidence coefficient is given respectively. The research results show that the surface subsidence coefficient of loess gully region should be mainly calculated by JZ, and the ratio of the height of the slope to the overall thickness of the loess cover should be considered. The JC of the ground surface subsidence coefficient should be calculated at aeolian sandy site. Through two engineering examples, the reliability of the piecewise function expression of surface subsidence coefficient with JC and JZ as independent variables is verified.

The 311101 first mining face in Bayangaole Coal Mine is taken as the example. Before mining in the working face, geophysical exploration project combining transient electromagnetic method with audio frequency electric perspective method are used to detect the abnormal water-rich area of the coal seam roof. Then the drilling project is arranged to dredge roof water and master the distribution of water inflow and water pressure. Based on the results of geophysical exploration and drilling engineering, the water-rich area on the roof of the working face is determined and divided. The results show that six abnormal water-rich areas are detected in the roof geophysical exploration project, and the water inflow and water pressure of the fifty-six roof water drainage boreholes are divided into four numerical intervals. After comprehensive analysis, the roof water-rich area of the working face is divided into four parts; in the mining process of the working face, it is obvious that the stepped increase will appear for the water inflow of the working face for every water-rich area. This phenomenon verifies the rationality and accuracy of water-rich partition of the roof aquifers.

Based on the research of landforms, hydrogeological conditions, roof hole water outflow of working face and goaf water outflow in deep buried coal seam area of Ordos basin, we constructed a working face roof water pre-drainage standard. The results showed that there were three type landforms (i.e. bedrock platform, sand and loess hill). The Quaternary water abundant in sand area was better than that in bedrock platform area and loess hill area, and the Quaternary aquifer was abundant water resource for the first section of Zhiluo formation. All coal mines could be divided three types according to initial water quantity and accumulative amount of water pre-discharge of working face roof borehole. Working face roof borehole outflow was small in Hongqinghe Mine and Weiqiang Mine (q0≤10.0 m3/h, Q100.0 m3/h, Q>100.0×104 m3).So we constructed a working face roof water pre-drainage standard. Working face did not need to carry out roof water pre-drainage when q0=0 to 10.0 m3/h, and water-bearing roof strips (q0>20 m3/h) should carry out water pre-drainage for the mines with q0=0 to 60.0 m3/h. But when q0>60.0 m3/h, roof water pre drainage had to be carried out for 600 m to 1 000 m working face phased and three months ahead. The final requirements were q1≤10.0 m3/h and p1≤1.2 MPa with 90% boreholes.

The 2# coal in Yuheng northern district is aquifer, which has the characteristics of high water pressure and strong water content. It brings serious safety problems to shaft construction in many coal mines in Yuheng northern district. In order to solve the problem of strong and rich water in coal seam during the construction of 2# coal auxiliary shaft ingate of Balasu Coal Mine, four grouting processes are divided, i.e. annular space closure of wellbore, drainage closure of perforation and drainage, grouting modification of coal seam and detection of water-stop effect, based on the idea of “drainage grouting and curtain closure”. Cement-based grouting material with setting property has successfully realized grouting and plugging in strong water-rich and high water pressure coal seam under hydrodynamic condition. It meets the requirements of cavern excavation in 2# coal shaft ingate. The grouting reform design of strong water-rich coal seam in Balasu Coal Mine solves the problem of coal seam water hazard in the construction process of the mine shaft horse head door.

The first mining face 122106 in Caojiatan Coal Mine was taken as the research object. The main water filling sources and water filling channels during the mining period of the working face are determined. Through hydrochemical analysis, we master the roof water-rich situation of the research area, and ensure the working face safe mining through the working face water inflow prediction. The results show that the main filling water sources during the mining period are the overlying Jurassic Yan’an Formation and Zhiluo Formation aquifers, and the weathered bedrock aquifers in some areas, and the main source of filling water is the water-conducting fracture zone of overlying rock. Audio frequency electric perspective method and transient electromagnetic method were used to explore the roof aquifers, and several water-rich abnormal areas were identified. Then, 3 water-rich segments were found in the roof through drilling. The water quality characteristics of different water-rich segments were judged by the combined water chemical analysis, and their hydraulic relations were analyzed. According to the hydrogeological analogy method, the water inflow after mining in the research area is predicted, compared with the actual mine, the predicted result is more accurate.

Research has been conducted on the metal cyclam complexes. The antiviral activity of these complexes has been investigated and results indicate their biological activity depends on membrane protein recognition and configurations.

Acetate binding to Zn (sub 2)-Xyl-bicyclam induces the formation of the unusual cis-Vconfiguration via chelation and second coordination sphere double H-bonding to diagonal cyclam NH protons. The method details the detection of at least six configurations for Zn (II) (sub 2)-Xyl-bicyclam in aqueous solution.