Study on distribution laws of ground stress at mining depth of-750 m level in No.2 Xinji Mine

Understandings of the ground stress distribution laws are crucial to design of roadways, mine layout, and supporting methods in underground mines. This paper presented a case study of distribution laws of ground stress at a mining depth of -750 m level in the No.2 Xinji Coal Mine. The magnitude and direction of the in-situ stress were measured using a hollow inclusion stress gauge setting three measuring points. The distributions of vertical and horizontal stress are then computed. The results show that the maximum principal stress at the depth of -750 m level was greater than the vertical stress, which was greater than the minimum principal stress. The maximum ratio of the maximum principal stress to the vertical stress was 1.74. The maximum horizontal principal stress was 1.97 ～ 2.13 times of the minimum horizontal principal stress. The results also indicate that the ground stress had a greater influence on the mine development than the vertical stress. The measured vertical stress was slightly less than the vertical stress calculated from overburden depth and density while the maximum principal stress was greater than the stress calculated from overburden depth and density. Furthermore, the Paleo-tectonic activities in Xinji mining area was strong, for which reason great attention should be paid for future mine design and mine development.