The Three Dimensional Stress Analysis of Two-Excavated Holes with Various Distances Using Finite Element Method

[[abstract]]目前世界各核能先進國家皆規劃以深層地質處置(Deep Geologic Disposal)概念為高放射性廢料之永久處置方式，而深地層下之岩石現地應力(in-situ stress)大小與方向為影響處置場穩定性之關鍵因素，本研究以高放射性廢料處置孔的設置為考量的重點，以了解處置孔間應力相互之影響程度。本研究利用有限元素分析程式SAP2000進行數值分析，假定處置孔深埋於地底500公尺處，且受到岩盤垂直均佈應力之荷重，以探討在5m、8m、10m以及12m四種不同處置孔間距影響下探討處置孔間之應力變化情形。 本研究之分析結果顯示，在地底500公尺下，當處置孔間距由5m變化至8m時，兩處置孔壁之應力大小會有明顯的變化。但是，當處置孔間距增加至10m後，兩處置孔壁的應力大小則逐漸趨於相等，即表示處置孔間之應力互制影響逐漸減小。基於上述之分析結果，得到在該處置深度下，設置處置孔時其間距最少應為10m，使得處置孔間之應力分布受到岩石現地應力所造成之應力影響減至最低。[[abstract]]The permanent disposal method of high-level radioactive waste using the Deep Geological Disposal concept has been adopted by all the advanced nuclear countries The magnitude and directions of the in-situ stress of rocks under deep ground are the key factors to influence the stability of disposal site This research focused on the layout of the deposition holes of high-level radioactive waste in order to capture the influence of stresses This research conducted the numerical analysis in order to study the stress variation between the deposition holes with various distances of 5m 8m 10m and 12m using the finite element program SAP2000 and assuming that the deposition holes are located at 500m depth and vertical rock stresses are uniformly loaded The analytical results in this research indicate that the magnitude of stresses obviously changes if the distance between deposition holes varies from 5m to 8m but the magnitude of stresses is approximately equal if the distance between deposition holes is increased to 10m i e the stress interaction between the deposition holes is decreased at this distance The above research results can conclude that the minimum distance between the deposition holes should be 10m between the deposition holes under the deposition depth in order to minimize the influence of in-situ stress of rocks to the stress distribution between the deposition hole