Research On Microseismic Monitoring And Warning Technology Of Shaft Wall Damage

The damage and destruction of shaft wall will have a huge impact on the safety production and economic benefits of coal mine,and in serious cases will directly lead to the production of coal mine,so it is particularly important to implement effective deformation and failure monitoring of shaft wall.There are many problems in the previous borehole wall monitoring methods,such as low accuracy,poor stability,unable to achieve fixed point monitoring and unable to distinguish effectively from the damage inside the borehole wall.Based on the relevant knowledge of microseismic monitoring technology,this paper conducts uniaxial compression experiments on concrete shaft samples through laboratory experiments and numerical simulation,explores the feasibility of microseismic monitoring and early warning technology for shaft wall damage,and applies the microseismic monitoring technology in coal mine shaft,providing a new idea and method for the monitoring and early warning technology for shaft wall damage.The main achievements are as follows:(1)The uniaxial compression experiment was carried out on the concrete shaft samples,and the distribution law of microseismic events in the shaft at different stages,the characteristics of microseismic signals in the process of shaft wall failure and the positioning and evolution law of microseismic events were obtained.At the initial stage of experimental loading,some microseismic events occur inside the wellbore,but the signal energy is generally small.In the middle stage of experimental loading,very few microseismic events occur inside the wellbore,and the energy is weak.At the late stage of experimental loading,a large number of high-energy microseismic events occurred inside the wellbore.The location results of microseismic events show that the occurrence rule of microseismic events is as follows: a small number of events are randomly distributed to a large number of events,and the concentrated area where the events occur is consistent with the damage and failure area of wellbore samples.The results show that the cumulative location evolution of microseismic signals and stress evolution have similar rules.(2)On the basis of theoretical analysis of elastic waves,wellbore models with different attributes and sizes are constructed to study the propagation characteristics of elastic waves in the wellbore.The results show that the phenomenon of rebound and energy dissipation occurs when the elastic wave reaches the edge of the wellbore model.Under the condition that no boundary is set at the edge of the wellbore model,the elastic wave will propagate along the edge of the model indefinitely until the energy is exhausted,and the propagation of the elastic wave in the wellbore follows the "shortest path" principle.By comparing the results of different positioning methods,a positioning method suitable for this study is proposed.(3)On the basis of laboratory experiments and numerical simulation studies,the microseismic monitoring technology is applied to the practical engineering of wellbore wall.Based on the research background of a mine shaft in Shandong province,a microseismic monitoring system is arranged in the-300m～-400 m section of the shaft to realize 24-hour continuous microseismic monitoring.During the monitoring period,the collected microseismic signal characteristics are analyzed,and the effective early warning discrimination is carried out on the shaft wall area where damage may occur,which verifies the feasibility of the microseismic monitoring and early warning technology of shaft wall damage,and provides a new idea and method for the shaft wall damage monitoring and early warning technology.