Date: Thursday,21th December,15:30-17:30

Site: Zonghe Building 424，综合楼424

Abstract:

Disturbed by excavations in subsurface structures,regional stress fields lose their stress balance state and the induced stress may exceed the strength of the rock mass,leading to seismicity at mines.Seismic monitoring systems greatly facilitate the application of seismic imaging for forecasting geohazards such as rockbursts and collapse at mines.Using existing microseismic data from mines to generate a database of time-lapse tomograms is a viable way for visualizing stress distribution so that trends of stress preceding and following significant seismic events can be analyzed.The highly-stressed volumes at mines are identified with seismic tomography as high velocity regions because the increased stress results in microfractures within the rock being closed,effectively increasing the elastic modulus of the rock resulting in elastic waves traversing the rock with greater velocity and less attenuation.Seismic tomography is capable of efficiently visualizing 3-D stress evolution and providing temporal-spatial stress evolution,providing insights into forecasting rock bursts at deep mines.

Profile:

Dr.Xu Ma is a postdoc associate in the Department of Mining Engineering at Virginia Tech.He received Ph.D.in Mining Engineering at Virginia Tech,with a focus on mining-induced sesismicity and passive seismic tomography application in mining.He obtained a master degree of Solid Mechanics at our home field- CUMTB and a bachelor degree of Mining Safety Engineering at North China Institute of Sci&Tech.Dr.Ma worked at National Energy Technology Lab,US Department of Energy from Aug.2015 to April 2017.His research interest falls into induced seismic hazard mitigation,carbon storage & sequestration,and hydrate-bearing sediments.Dr.Ma was a recipient of Syd.Peng Ground Control Scholarship and U.s.Department of Energy ORISE fellowship.