Jiayuan Cao

Submarine mine water inrush has become a problem that must be urgently solved in coastal gold mining operations in Shandong, China. Research on water in subway systems introduced classifications for the types of mine groundwater and then established the functions used to identify each type of water sample. We analyzed 31 water samples from −375 m underground using multivariate statistical analysis methods. Cluster analysis combined with principle component analysis and factor analysis divided water samples into two types, with one type being near the F3 fault. Principal component analysis identified four principle components accounting for 91.79% of the total variation. These four principle components represented almost all the information about the water samples, which were then used as clustering variables. A Bayes model created by discriminant analysis demonstrated that water samples could also be divided into two types, which was consistent with the cluster analysis result. The type of water samples could be determined by placing Na⁺ and CHO₃⁻ concentrations of water samples into Bayes functions. The results demonstrated that F3, which is a regional fault and runs across the whole Xishan gold mine, may be the potential channel for water inrush, providing valuable information for predicting the possibility of water inrush and thus reducing the costs of the mining operation.

Cracks are critical for the deformation and failure of rock masses, but the effects of real cracks are rarely considered when evaluating the stability and safety of practical engineering. This paper presents a study on the application of fractures in the Sanshandao Gold Mine. Field investigation and statistical analysis methods were adopted to obtain the distribution laws of the cracks. Laboratory tests, MATLAB programming, and simulation using the software, GDEM (Gdem Technology, Beijing, China, Co., Ltd.), were employed to study the mechanical behaviors of rock masses with real fractures after excavation. The main results are as follows: (1) Three sets of highly discrete cracks were developed in the study area. Their inclination and dip can be approximately considered to follow a Gaussian distribution or uniform distribution. They had close ties to the three faults developed in the mining area. (2) Compared with the model that did not consider cracks and the model processed by the equivalence idea, the surrounding rock deformation caused by excavation of the model that considered real cracks was larger than that of the former and smaller than that of the latter. However, its influence range was larger than that of the other two models. The results show that it is reasonable to use three sets of discrete cracks to characterize the fracture distribution of the surrounding rock. In the evaluation of roadway stability, it is not advisable to use the equivalence method to deal with all the cracks. Considering a part of the cracks that are compatible with the size of the calculation model, a relatively accurate evaluation can be obtained in terms of the deformation, failure, and permeability changes of the surrounding rock.