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Mine water inrush seriously threatens the safety of coal mine production. Quick and accurate identification of mine water inrush sources is of great significance to preventing mine water hazards. This paper combined partial least squares-discriminate analysis (PLS-DA) with inrush water chemical composition to identify the source of water inrush from multiple aquifers in mines. The Renlou Coal Mine in the Linhuan mining area was selected for this study, and seven conventional water chemical compositions from 54 water samples in three aquifers were collected and tested, of which 45 water samples were used to establish the PLS-DA discriminant model, and nine were used to test the prediction effect. To improve model accuracy and predictive ability, hierarchical clustering analysis method was used to eliminate seven unqualified water samples to reduce the errors caused by improper data. PCA and PLS-DA methods were used to analyze and process the remaining water sample data, and on the basis of PCA analysis, the remaining 38 water samples were used to establish the PLS-DA discriminant model. The model was validated using permutation and external prediction tests. The research shows the following results: (1) Both PCA and PLS-DA methods can distinguish water samples from three different water sources, but the classification effect of PLS-DA was better than PCA because it can strengthen the difference of water chemical composition between different water sources. (2) The correct discrimination rate of the PLS-DA discriminant model was as high as 100%, and permutation tests showed that the model was not overfit. External validation found that the model had good stability and discrimination. (3) HCO3- and total dissolved solids (TDS) were the most important differential marker compositions that affected the discrimination results based on Variable Importance for the Projection (VIP) scores. The discriminant model established in this study combined the advantages of principal component analysis and multiple regression analysis, providing a new method for accurately identifying the sources of water inrush in mines.

At present, the instability of floor roadway is increasingly serious, and even the representative high-performance U-steel support cannot provide roadways with completely effective support. Thus, the mechanism of roadway deformation should be analyzed rather than only considering the roadway support. To study the influence of coal mining on the stability of floor roadways under tectonic stress, taking the floor roadway under No.8 coal seam in Luling Coal Mine in China as the research object, the roadway deformation was tested with and without tectonic stress through the similar physical simulation method. Finally, the changing mechanisms of the stress field, fracture development and displacement field of the surrounding rocks in the floor roadway under mining effects were systematically analyzed. The results show that: (1) under the same stress condition, deformation and fracture of the floor roadway increase with the increase of mining step; (2) without tectonic stress, the maximum hoop stress of the floor roadway arch foot is 32.5 MPa located 2.7 m away from the roadway wall. Meanwhile, under tectonic stress, the maximum stress changes to 38.5 MPa at 3.6 m away from the roadway wall; (3) whether under mining effects or not, the deformation time is longer and deformation failure is larger under tectonic stress. The conclusions indicate the tectonic stress field has significant on roadway deformation and failure, which can provide the technical reference for the optimization of mine roadway layout.

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