The magnitudes and orientation of in situ stress affect the stability of mine openings, as well as the type and amount of ground support needed to maintain a safe working environment for miners. Using hollow inclusion stress cells, researchers obtained 13 in situ stress measurements from 6 coal mines Kailuan mining area, China. According the analysis of the measurement data, the characteristic of in-situ stress field is obtained. At last the relation between in situ stress and geological structure was discussed. The result provided a more precise and reliable stress environment for design, construction and production of deep mining in Kailuan mining area.
Kailuan mining area, located in Tangshan city, north China, is the main coal production bases of China. It includes 11 coal mines and 670 km2 (Figure 1). Most of Kailuan mining area is covered by the Quaternary alluvial deposits. The strata of carboniferous and Permian systems are 490–530 m thick. There are 15–20 coal seams, 20–28m thick. The minable seams in descending order include No.5, No.7, No.8, No.9, No.11, No.12, and No.14. With 130 years of mining history, a lot of mines have already entered in deep mining. Such as Tangshan mine is 841 m; Linxi mine is 899 m; Lujiatuo mine has reached 827m deep; Fangezhuang mine is 829 m. The rock mechanics problems caused by the deep mining are the focuses in the fields of mining engineering. In situ stress is fundamental force which caused rock failure, supporting invalidation, even mining dynamic phenomena (coal and gas outburst, rockburst and mining induced seismism). In many factors which affect the stability of mining engineering, the in situ stress is the most important and most fundamental factor. But previous researches were focus on larger region and depth.