Research On Mechanism Of Thick Sand Dynamic Load Transmitting In Shallow Seam

The paper is on the basis of my supervisor, Professor Huang Qingxiang's item financially supported by the National Natural Science Foundation. Through the material analysis of the surveying of ground behavior and the course of ground subsidence in Shen Dong mining field, the load transmitting effect and its dynamic character caused by the failure of thick sand stratum in shallow seam is exposed. Through the simulating test, the "arc" type failure in preliminary stage, periodic "arc shell" failure, "arc and beam" type failure in critical mining,"arc pillar" failure in periodic stage and unloading arc formed within two arc-pillars are obtained. Through embedment of surveying blocks in simulating model and appliance of intelligent acquisition system,dynamic load's distributing character and transmitting law of thick sand stratum on key stratum (key blocks) are presented. On the basis of test research,unloading arc calculating model and arc beam mechanical model are set up, thick sand stratum's rupture law is exposed. On the basis of unloading arc mechanical model, height of arc in preliminary stage and arc formed within arc-pillars are confirmed. Calculating formula of rock factor and time factor of load transmitting in calculation of roof structure are obtained. Finally, the conclusion is tested and verified by practical examples analyzing.