The Law Of Mining Induced Fault Activation And Micro-seismic Monitoring Research

Fault is an important geological factor affecting mining safety. The energy filed balance, displacement field balance and stress field balance surrounding fault would be broken up because of underground mining actives or construction actives. The fault slippage would happen if those actives were not smoothly. It’s a great threat for human and device safety. How to achieve mineral maximum recycling in a safe and efficient way has puzzled the entire professional for a long time. So it’s meaningful to do the research of fault activation induced by mining. Theoretical analysis, computer simulation and field monitoring were combined used for exploring the law of fault activation induced by mining activities in this paper. The whole analysis was divided into three parts: 1.Theoretical analysis including Microscopic statistical analysis and macroscopic mechanical analysis. 2. Numerical simulation. Stress field distribution affecting factor analysis based on different model and the entire process of the dynamic response to mining activities. 3. Field monitoring. Combining with the IMS micro-seismic monitoring results to discover the law of ground-pressure which surrounding the fault. The main research results were shown as following:1. The numerical simulation softwareDFlac3 was used for built different model, and then handling stresses distribution affecting factor analysis after macro mechanics analysis of fault activation. The key stress distribution affecting factor included fault angle, internal friction angle of fault, seam elastic modulus, Poisson’s ratio of seam and boundary stress.2. A numerical model of the west part of Piaotang Tungsten tin ore was built. Then two different mining processes were simulated. One way was mining spot moving towards to fault direction in hanging wall. Another way was mining spot moving towards to fault direction in foot wall. The stress distribution had obvious difference because rock-mass continuity damaged by fault. Two kinds of mining spot arrangement, the impact on the fault and the surrounding rock-mass difference was small. The normal stress changed litter earlier then shear stress when the distance between mining spot and fault became nearer and nearer. Then the displacement analysis also was used for confirm the critical condition of fault activation. No matter what kind mining method, the fault activation would happen when the distance between working face and fault less than 10 m.3. The IMS micro-seismic monitoring system was designed according to current mining situation and ground-pressure distribution in Piaotang Tungsten ore. The research was shown that seismic parameters are induced engineering disturbances. The micro-seismic active regions were corresponding to Mining engineering operating point.The underground pressure active period was along with the change of external disturbances in time and space. The cumulative displacement and apparent stress were small, which indicated that rock stability was good surrounding mining spot, underground pressure activity still weak. And fault activation was also not happen, still in the quiet period. Because of the influence of the fault, mine in the actual production in addition to pay close attention to the evolution of the seismic parameters, also should strengthen the on-site screening work.