Study and application of dynamic response characteristics of support in full-mechanized top coal caving with large mining height

The dynamic response characteristics of stope support include the information of support resistance increase and live column shrinkage, which is not only an important index to reflect the strength of mining pressure behavior in working face, but also the basis for studying the dynamic interaction between support and surrounding rock. Taking the 122108 working face of Caojiatan Coal Mine as an example, heoretical analysis and mathematical statistics were used to clarify the dynamic response characteristics of the support during the mining process, reveal the resistance increasing mechanism of the support in different bearing stages, and analyze the characteristics of mining pressure before and after fracturing of the working face, and carry out research and application of the resistance increasing characteristics of the support before and after pressure. The results show that: in continuous cycles, the support shows the characteristics of “high resistance and continuous shrinkage of the living column”, then the working face is pressed, and the information of support shrinkage can be used to evaluate the apparent strength of the previous pressure. When the roof is not broken, the generalized Kelvin model can be used to characterize the slow movement of the roof. After the roof fracture, the support shows a logarithmic resistance increase at a given deformation stage, and the resistance increase rate is determined by the support stiffness, the controlled roof distance and the unstable state of the broken roof, and the support resistance increases exponentially or linearly at the given load stage. The dual-factor analysis method of support resistance and height can accurately judge the characteristics of mine pressure behavior in the working face with strong mine pressure. After fracturing, the proportion of the pressure step distance of more than 30 m in the working face is greatly reduced, and the proportion of the continuous pressure distance of 10 to 28 m is reduced to 2%. The normal distribution curve of cumulative shrinkage and shrinkage speed of support decreases as a whole. The change of the type and rate of resistance increase of support is a remarkable feature to judge whether the working face is under pressure or not, and it can be used as a new method to predict the pressure of working face. The result of increasing resistance by homogenization of support can be used to predict roof pressure and invert the macroscopic subsidence change of roof. The above research results have certain reference significance for improving the interaction between support and surrounding rock and guiding the early warning and prevention of roof disasters in working face.