Failure Mechanism Of U-steel Supporting Under Different Loads

As the coal mining depth and intensity increase, more and more U-steel brackets are used in the various major coal mine roadway support, but the carrying capacity of the stent isn’t so high as the intensity calculated results. Meanwhile, the carrying capacity of the shrinkable arched U-steel brackets of high impedance isn’t fully developed in many cases, and then the bearing structure is easy to lose its stability. Therefore, what is urgent to solve the key issues is to choose and develop suitable type of frame according to the local conditions as well as to determine the reasonable parameters in order to make the metal support play its best besides the steel quality and accessories as well as backfilling the section. Through the theoretical analysis, this thesis makes the deep research on the primary factors of affecting the instability and failure of the U-steel by combining the on-spot practice with the computer imitating.This paper describes first the main factors to affect the U-steel bracket carrying capacity, U steel material and cross-section parameters, the geometry and dimensions of the bracket, and load distribution of a certain impact on the carrying capacity of the bracket. Moreover,the paper selects U29steel, uses ANSYS finite element simulation software, establishes U-shaped steel analysis model, simulates and analyses the distribution of the internal forces and curved distance of the semi-circular arch and arc arch inclined legs shaped two U-steel bracket under the uniform and non-uniform loads. Followed by analyzing the impact of different leg length, we can identify the most beneficial type of playing the carrying capacity of the U-steel bracket in several different legs of the U-steel and on this basis to identify the weak points of the structure of the steel supports and to make for the structural compensation, and to analyze the distribution of the internal force of the structural compensation in front of and behind the stent. Finally we can find out the primary and secondary relationship of the destruction of U-steel through orthogonal experimental design on different type of load, load size, as well as analysis optimizedly of the size and location of the binding.This thesis can help find out the way to make full use of the U-steel carrying capacity through the aboved simulating results and analysis and come up with the designing method and even apply those ways to the on-site situations to test the effects.