Rockburst Mechanism Of Skip Mining In Deep Coal Mines And Its Application

Skip mining is one of the mining methods to control surface subsidence,protect ground buildings and ecological environment.A large number of occupied coal resources can be recycled with this method.However,in recent years,rockburst accidents have occurred frequently in skip-mining mines in the eastern part of China,resulting in many casualties and a considerable loss of equipment.This demonstrates the defects of design concepts and rockburst prevention of the traditional skip-mining methods,as well as the lack of control techniques during skip mining.Therefore,Shandong Energy Group Co.,LTD and other coal enterprises have listed rockburst prevention and control as an important issue of safety mining to research in skip mining in deep mines.Rockburst mechanism needs revealing in skip-mining mines,in order to provide scientific basis for skip-mining design and rockburst prevention and control.This thesis studied the relationship between the overburden structure and stress based on theoretical analysis,numerical simulation,field measurement,case study and engineering analogy.The rockburst evaluation method was established by proposing equivalent depth and strength of surrounding rock.The practical and effective techniques for rockburst prevention and control during skip mining under thick-hard strata and thick-soft strata.The main innovative results are as follows.(1)A large-scale structural model in high overburden with thick-hard rock strata were proposed,and the rock formation condition and mechanical criterion are established.Based on this model,the mechanical mechanism of strong rockburst often occurs on the boundary of the skip-mining area.(2)The calculation methods of equivalent mining depth and critical rockburst depth were proposed.The reasons for the existence of different critical rockburst depths in single roadways,longwall panels of skip mining in solid coal body and isolated coal pillars.The results provide a theoretical basis for the design of rockburst prevention measures in different stages of skip mining.(3)The differences among overburden structure,mining stress distribution and rockburst mechanism during skip mining under thick-hard strata and thick-soft strata were compared.This comparative analysis provided the technical basis for mining design and rockburst prevention under the two typical overburden conditions.(4)According to the characteristics of stress distribution during skip mining and the equivalent strength of surrounding rock,the traditional multi-factor evaluation method for rockburst prevention was improved,and a new multi-factor evaluation method was proposed,which agrees well with engineering application.The research results in this thesis have been successfully applied in several coal mines in Shandong Energy Group Co.,LTD.A large number of rockburst accidents have been reduced and the damage extent was lessened.