Groundwater recharge and runoff conditions are ascertained in the Suixiao coal-mining district using the hydrogen and oxygen isotopes and the trace elements in the unconsolidated pore aquifer of the Cenozoic group, the fissured sandstone aquifer of the Permian system, and the karst fissured limestone aquifer of the Carboniferous Taiyuan Formation and the Ordovician system, which are the main recharge aquifers during coal mining. The main water–rock interactions are pyrite oxidation, cation exchange and adsorption, and carbonate acidification, which are educed by principal component analysis of conventional ions. These results combined with geological conditions prove that hydraulic connection exists generally between the main recharge aquifers, and the groundwater circulation is controlled by faults in the sandstone and limestone aquifers. The water–rock interaction is very weak in the east of the district, which is proved to be a recharge area by Fisher discriminant analysis. This study provides the theoretical basis for the hydrochemistry exploration and the establishment of a water-inrush warning system in a concealed coalfield.

为研究岩石含水率对蠕变的影响,将含水开关与蠕变损伤阀值引入蠕变模型,实现了含水劣化与蠕变损伤在本构关系上的耦合,建立了岩石含水蠕变损伤模型.模型与某软岩的三轴压缩蠕变试验结果取得了较好的拟合效果,并由麦夸特法十通用全局优化(LM-UGO)算法反演出了模型参数随岩石含水率的变化规律.在C++语言和FLAC3D中Fish语言的环境下,通过推导模型本构方程的三维差分形式,并利用FLAC3D所提供的接口实现了模型的二次开发.通过对开发的岩石含水蠕变损伤模型进行算例验证和分析,验证了模型的可靠性,也得出了软岩巷道蠕变变形随围岩含水率增大而增加的结论,进一步反映出蠕变模拟计算中考虑岩石含水率的必要性.

The Poynting-Thomson creep model is one of the classical combined creep models; however, it fails to demonstrate the plastic creep and the accelerated creep stage, which limit the popularization and the use of the model. The New Poynting-Thomson (NPT) creep model is established to enhance the existing Poynting-Thomson creep model by the damage theory and the viscoplastic unit in this paper. On the basis of deducing its constitutive equation in three-dimensional finite difference form, The NP-T creep model is secondarily developed by using Visual C++ language and FLAC(3D) built-in FISH language. The results of a parameter inversion indicate the superiority of the NP-T creep model that can be applied in non-uniform stress field. After validating its accuracy by the FLAC(3D) software, the NP-T creep model is used in a numerical simulation to reflect that the roadway stability is gradually weakened with the increase of the surrounding soft rock thickness.

Coal mining is bound to destroy the natural hydrochemical environment.However,hydrochemical studies of a groundwater system of multi-aquifer in the mining district rarely focus on the essence of hydrochemical evolution under the mining-induced disturbance in view of space and time.The Linhuan coalmining district is taken as an example to reveal the mechanism of water-rock interactions under the mininginduced disturbance by using the principal component analysis based on conventional ions over the years.The result shows that the first principal component represents the dissolution of carbonate and sulfate and oxidation of pyrite and the second principal component represents the exchange and adsorption of cation and desulphidation.Under the mining-induced disturbance,dissolution of carbonate and sulfate and oxidation of pyrite wear off in the main inrush-water aquifers in the mining district,but the change characteristics of exchange and adsorption of cation and desulphidation are insignificant.The research will provide a theoretical support for the identification of water-inrush source and also for the protection and utilization of groundwater in mining districts.

Conventional ions (K++Na+、Ca2+、Mg2+、Cl-、SO2-4、HCO-3、CO2-3), pH value and TDS of main inrush aquifers including the fourth aquifer of unconsolidated formation,the fissured aquifer of coal measure and the karst aquifer of Taiyuan formation in the Suxian mining area were collected to choose the appropriate ground-water flow path and mineral phase. Based on the groundwater flow path and the mineral phase, the hydrogeo-chemical model was established to quantitatively simulate the hydrogeochemical evolution in the mining area. From the simulation, the fourth aquifer of unconsolidated formation had a close hydraulic connection and was characterized by the pyrite oxidation and the cation exchange and adsorption in the water-rock interaction. The fissured aquifer of coal measure had poor groundwater runoff condition so that the pyrite oxidation and the cation exchange and adsorption tended to be stable. The east-middle of karst aquifer of Taiyuan formation with good hydrodynamic condition was characterized by the carbonate dissolution-precipitation while the western with bad hydrodynamic condition was characterized by the pyrite oxidation and the cation exchange and adsorption. The research hopefully provides a theoretical support for the prevention and treatment of mine water hazard and also for the exploitation and utilization of groundwater in the concealed coal mining area in North China.

In order to give prominence to fundamental significance of rare earth elements in application of tracing ground water circulation in deep aquifers,the main inrush aquifers of deep mining such as the fourth aquifer of unconsolidated formation,the coal sandstone fissure aquifer,the Carboniferous karst aquifer of Taiyuan formation and the Ordovician karst aquifer in Suxian-linhuan mining area were taken for example,and geochemistry parameters of rare earth elements(LREE/HREE,(La/Yb) N,δEu,δCe,(La/Sm) N,(Gd/Yb) N and Eu/Sm) and conventional ions (K + + Na +,Ca2 +,Mg2 +,SO42-,Cl-,HCO3-and CO32-) of ground water samples from the main inrush aquifers were selected as analyzing variables of principal component analysis.Through the comparative study of principal component analysis,the controlling elements of geochemistry parameters of rare earth elements and hydrogeochemical principle of fractionation of rare earth elements in deep ground water were illuminated.Moreover,based on the conceptualization of geological and hydrogeological conditions and the study of distribution and fractionation of rare earth elements in the mining area,the deep groundwater circulation pattern was put forward that the water source recharges the main inrush aquifers through three paths of nearly horizontal seepage,nearly vertical seepage and mixed seepage.The results provided theoretical basis for prevention and control of deep groundwater disasters,protection and utilization of deep groundwater resources in mining areas.