Analysis of the characteristics of in-situ stress field and fault activity in the coal mining area of China

The study of in-situ stress field is an important task in rock mechanics and mining engineering.With the coal mining goes into deep mining, the effect of in-situ stress is more prominent.Some new understandings about the in-situ stress field distribution characteristics and the relationship between in-situ stress and fault activity in China's coal mining area are obtained with the analysis of the 219 sets of measured in-situ stress data.There are mainly two types of stress field in China coal mining area:σ_H> σ_h> σ_vand σ_H> σ_v> σ_h, but the type of σ_H> σ_v> σ_h accounts for a larger percentage.In the research area, the high ground stress is the majority, the medium stress and the super high stress mining area also occupy a certain proportion, and the low stress mining area is the least.The maximum horizontal principal stress, the minimum horizontal principal stress and the vertical principal stress almost linearly increase with the depth, and the horizontal tectonic stress is in the leading position.The three lateral pressure coefficients decrease with the increase of depth, K_H gradually tends to 1.31, K_h gradually tends to 0.74 and K_av gradually tends to 1.03.The distribution of horizontal differential stress is discrete, its range is from 0.85 MPa to 19.51 MPa and the average is 8.80 MPa.Ratio of maximum horizontal principal stress and minimum horizontal principal stress is mainly concentrated from 1.5 to 2.0.The faults of the study area are less prone to sliding instability phenomenon when the friction coefficient are 0.6 and 1.0 under the current stress state, in the overall evaluation of the fault stability of the study area, the standard of the fault sliding instability criteria for the friction coefficient of 0.6 is more appropriate.