Investigation on the ultimate load bearing capacity of U-shaped steel arch support in coal bursting mine

The damage degree of the surrounding rock in the coal mine roadway is closely related to the support form, thus to carry out research on the ultimate bearing capacity of U-shaped steel support in coal bursting mine is of important guiding significance for the prevention and control of coal burst.Taking a typical coal bursting mine in Yima Coalfield as the engineering background, a theoretical calculation mechanical model of U-shaped steel deformation under uniform loading is established and the analytical solution of the overall deformation is given, then deformation of U-shaped steel and roadway under the action of uniform and non-uniform load is compared, and the affordable ultimate load from overlying strata and applicable ultimate depth of U-shaped steel support is studied when the load increases.The change of approach amount and speed of the roadway roof and floor through on-site monitoring is obtained, and improving the bearing capacity of U-shaped steel support to control the deformation of roadway and coal burst is analyzed.The results show that: with the increase of load, there will be a sharp acceleration point in the deformation and strain energy of roadway, which can be used to determine the applicable ultimate depth of U-shaped steel support.The applicable ultimate depth of U-shaped steel under uniform loading is 1 600 m, and the value is 1 600 m under the non-uniform loading.When the ultimate depth is reached, U-shaped steel will be completely in failure state, and the deformation of roadway will increase rapidly.When designing U-shaped steel support for the roadway of coal bursting mine, it is very important to improve the contact condition of surrounding rock support and apply uniform load to the U-shaped steel support boundary to ensure good contact between surrounding rock and U-shaped steel, and improve the bearing capacity of U-shaped steel.U-shaped steel support with greater bearing capacity can absorb more energy released from surrounding rocks, and better control the approach amount between the roof and floor of the roadway, preventing the deformation of the roadway from increasing rapidly, thus the stability of the roadway is ensured and the coal burst in the roadway is effectively controlled.