摘要：

本研究首先以二維顆粒流程式(PFC)模擬小林村崩塌,將垂直力量所記錄之震動訊號利用Hilbert-Huang transform (HHT)加以分析,將四個監測點所得到之震動訊號繪製成時頻圖,可估算出崩塌持續時間,並與先前現地踏勘所得到的堰塞壩資訊及甲仙寬頻地震測站所記錄之完整震動訊號做比較.本研究再以顆粒流程式(PFC)與連體程式(FLAC)耦合方法,建立山崩流動過程之數值模型,以小林村山崩為案例.以離散元素方法(PFC)模擬山崩產生的岩塊散開滑動與流動過程,當岩塊撞擊有限差分數值模型(FLAC)構成的連體網格時,兩程式在同一時步內會相互交換力與速度,並設置監測點偵測其震動訊號,再利用HHT分析所得震動訊號之時頻圖,探討其震動頻率特徵,並與距離小林村11.4公里之甲仙寬頻地震站之訊號記錄比較.進行各項參數案例分析,更深入地探討各項參數對數值模型的影響,希望藉由此新的方法更進一步貼近真實崩塌情況.本研究在相同邊坡上建立一場落石之案例,藉由模擬石塊自由墜落(free fall)至邊坡,並在邊坡設置多個監測點,分析單一巨石撞擊地面產生之震動訊號,可從時頻分析中得到震波傳遞之振幅速度,並探討其能量隨距離增加或地質材料不同而產生衰減的情況.A two-dimensional numerical coupling approach using the Particle Flow Code (PFC) and Fast Lagrangian Analysis of Continua (FLAC) code was developed to simulate the flow process of landslides and rock avalanches. The Xiaolin rock avalanche was used as a case study. The sliding of the rock fragments was simulated by PFC. When the rock fragments impact on the top boundary of FLAC, forces and velocities of the boundary grids were transmitted between the two codes. Monitoring locations were assigned in the coupled numerical model to record the seismic signals induced by the simulated rock avalanche. The time-frequency spectrograms of the seismic signals were analyzed using Hilbert-Huang transform (HHT) for examining the seismic characteristics. The simulated results were compared with the seismic signals recorded during the landslide from a broadband seismic station, SGSB, which is 11.4 km away from the Xiaolin landslide site.A rock-fall case was established using the same slope to simulate the signal induced by a single free falling rock. Monitoring locations were assigned in the coupled numerical model to record the seismic signals. The time-frequency spectrograms of the seismic signals were analyzed using HHT to examine the amplitudes of the seismic wave and the propagated velocities. The energy attenuation of the seismic wave versus distance and for different geological materials were analyzed.

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