[[alternative]]A Study on the Stress Distribution Behavior of Layered Rocks by FLAC

[[abstract]]本文利用FLAC程式中橫向等向性及非均質的岩盤材料組成模式模擬非等向性岩層之垂直應力與開挖後側向岩壓之分布。主要探討的參數有層理之方位、間距、勁度比，及岩石材料之彈性參數。研究結果顯示：(1)開挖前現地岩盤之應力分布與節理傾角及勁度比(正向勁度比剪勁度)有極大關係，其結果亦可與Bray理論解比較驗證；(2)開挖後層狀岩盤之側向應力分布與地表沈陷量亦與層理之間距與方位有關，且呈現異向性行為；(3)砂頁岩互層之側向應力分布可以砂岩與頁岩之各別土壓為上下界預估。[[abstract]]The purpose of this paper is to analyze the principal stress distribution and lateral stress of layered rocks. The 'Elastic Transversely Isotropic Model' in FLAC code is adopted to model the anisotropic characteristic for a rock formation, The result of FLAC analysis is first evaluated by the Bray's formula. Then the anisotropy of the principal stress distribution for a layered rock mass under line load is discussed. It is founded that the anisotropy of stress distribution is depended on the joint orientation and the normal/shear stiffness of the joints. In addition, the lateral stress distribution behavior in these layered rocks due to excavating is also examined. It reveals that the lateral stress of the layered rocks at rest is different from the theoretical value in an isotropic soil, but depended on both the joint orientation and joint properties. Moreover, the lateral stress for the alternation of the sandstone and shale is also discussed. It shows that the lateral stress for the alternation formation is located between the two elastic lateral stresses of the sandstone and shale.[[sponsorship]]中國土木水利工程學會資訊委員會; 中興大學土木工程學系[[conferencetype]]國內[[conferencedate]]20000217~20000218[[booktype]]紙本[[iscallforpapers]]Y[[conferencelocation]]臺中市, 臺