Characteristics of the In Situ Stress Field in the Yadian Coal Mine, Central China: Implications for Roadway Differential Deformation.

To study the in situ stress mechanism for different deformations of roadways in different directions, in this paper, we used the method of stress relief with a hollow core to measure the in situ stress of roadways with different degrees of deformation in the Yadian coal mine. The results showed that the in situ stress field was generally σH > σh > σV, indicating a typical reverse faulting stress regime. The present in situ stress field was the main factor for roadway differential deformation. The σH orientations were ESE and ENE-trending, which were consistent with the regional tectonic stress field in North China. The instrument for monitoring the abscission layer deformation indicated that the NS-trending roadway (cut-hole) deformation time approached stability after approximately 1-2 months, while it was 5-10 days for its EW-trending counterpart. The study of stress gradient shows that the stress state of the Ordos Basin has changed at a depth of 600 m, which is related to multiple tectonic events from the Late Paleozoic to Cenozoic in the Ordos Basin. The comprehensive analysis results show that the differential deformation of roadways is affected by many factors, such as the buried depth of the stratum, lithology and structural characteristics, fracture development degree, mining influence, composite deformation mechanics mechanism of weak swelling rock stratum, in situ stress field, tectonic stress mechanism, fracture development, etc.