This paper focuses on the impact of past mining on public safety.It emphasizes the need to understand the induced seismic hazard and consequently improve the post-mining management procedures and legislations,as many ...This paper focuses on the impact of past mining on public safety.It emphasizes the need to understand the induced seismic hazard and consequently improve the post-mining management procedures and legislations,as many mining sites are located in proximity to populated areas.Due to many challenges and complexity of the post-mining environments,induced seismic hazard nowadays remains largely unknown.However,the return experience of several post-mining sites in recent decades have shown us that the mine flooding and/or degradation of mining works can lead to the stress perturbations,inducing the seismicity and the reactivation of the surrounding geological faults.Hence,it is important to advance the seismic monitor-ing and research of seismicity in flooded post-mining districts.As the number of mine closures worldwide is rising,it can be expected that flooding induced reactivation of the surrounding faults becomes a more often observed phenomenon.We present in this paper the experience of the abandoned flooded coal mine of Gardanne in France,which has been experiencing post-mining seismicity problems since its closure in 2010.We show the results of a recent study of seismic multiplets and clustering of seismic events,as well as their spatio-temporal activity compared to meteorological conditions.These results provide us new insights as well as lead to raising new questions on seismic sources and triggering mechanisms.展开更多
A simplified method for the simulation of the ergodic spatially correlated seismic ground motion is proposed based on the commonly used original spectral representation method. To represent the correlation in the grou...A simplified method for the simulation of the ergodic spatially correlated seismic ground motion is proposed based on the commonly used original spectral representation method. To represent the correlation in the ground motion, the phase angles are given by explicit terms with a clear physical meaning. By these explicit terms, the computational efficiency can be improved by converting the decomposition of the complex cross-spectral matrix into the decomposition of the real incoherence coefficient matrix. Double-indexing frequencies are introduced to simulate the ergodic seismic ground motion, and the ergodic feature of the improved method is demonstrated theoretically. Subsequently, an explicit solution of the elements of the lower triangular matrix under the Cholesky decomposition is given. With this explicit solution, the improved method is simplified, and the computational efficiency can be improved greatly by avoiding the repetitive Cholesky decomposition of the cross-spectral matrix in each frequency step. Finally, a numerical example shows the good characteristic of the improved method.展开更多
文摘This paper focuses on the impact of past mining on public safety.It emphasizes the need to understand the induced seismic hazard and consequently improve the post-mining management procedures and legislations,as many mining sites are located in proximity to populated areas.Due to many challenges and complexity of the post-mining environments,induced seismic hazard nowadays remains largely unknown.However,the return experience of several post-mining sites in recent decades have shown us that the mine flooding and/or degradation of mining works can lead to the stress perturbations,inducing the seismicity and the reactivation of the surrounding geological faults.Hence,it is important to advance the seismic monitor-ing and research of seismicity in flooded post-mining districts.As the number of mine closures worldwide is rising,it can be expected that flooding induced reactivation of the surrounding faults becomes a more often observed phenomenon.We present in this paper the experience of the abandoned flooded coal mine of Gardanne in France,which has been experiencing post-mining seismicity problems since its closure in 2010.We show the results of a recent study of seismic multiplets and clustering of seismic events,as well as their spatio-temporal activity compared to meteorological conditions.These results provide us new insights as well as lead to raising new questions on seismic sources and triggering mechanisms.
基金supported by the National Natural Science Foundation of China(Nos.90815020 and 50808067)
文摘A simplified method for the simulation of the ergodic spatially correlated seismic ground motion is proposed based on the commonly used original spectral representation method. To represent the correlation in the ground motion, the phase angles are given by explicit terms with a clear physical meaning. By these explicit terms, the computational efficiency can be improved by converting the decomposition of the complex cross-spectral matrix into the decomposition of the real incoherence coefficient matrix. Double-indexing frequencies are introduced to simulate the ergodic seismic ground motion, and the ergodic feature of the improved method is demonstrated theoretically. Subsequently, an explicit solution of the elements of the lower triangular matrix under the Cholesky decomposition is given. With this explicit solution, the improved method is simplified, and the computational efficiency can be improved greatly by avoiding the repetitive Cholesky decomposition of the cross-spectral matrix in each frequency step. Finally, a numerical example shows the good characteristic of the improved method.
