黃燦輝2006-07-252018-07-092006-07-252018-07-092002http://ntur.lib.ntu.edu.tw//handle/246246/2782西部麓山帶以未變質的第三紀碎屑沈 積岩為主。由於該岩層岩性軟弱，因此過 去之隧道工程，在遭遇此類岩層時常引致 許多工程災害。有鑑於隧道開挖後的變形 性及穩定性，深受軟弱砂岩之力學行為所 影響，然而目前對於軟弱砂岩之力學特性 尚無通盤性之了解。本研究即以台灣中、 北部麓山帶之軟弱砂岩為研究對象，深入 探討其力學行為。研究中共包含15 種砂 岩，含括粗顆粒石英砂岩、細顆粒雜砂岩 及細顆粒石灰質砂岩，年代涵蓋範圍由漸 新世至上新世。本研究首先進行一系列不 同體積應力作用下之純剪應力路徑與傳統 三軸實驗，探討其破壞包絡線及應力–應 變行為之變化。在針對實驗結果歸納出軟 弱砂岩之變形特性後，並據以建構一軟岩 組成模式。該組成模式為一彈塑性模式， 可預測麓山帶砂岩主要之變形特性，包括 (1)體積應力作用下，非線性彈性變形及塑 性應變閉鎖情形；(2)剪應力作用下，剪應 力與彈性體積應變之偶合行為；(3)橢圓帽 狀塑性勢能面之存在。經與實驗資料相較 後，可發現本研究模式具有甚佳之模擬結 果。Owing to the high porosity, low strength, and large deformability of weak sandstone, tunnel construction in western Taiwan encounters lots of excess deformation. This research first explores this problem from experimental data. A series of triaxial tests have been carried out to investigate the deformational characteristics of weak sandstone. The experimental results indicate that: (1)significant plastic volumetric strain comes up at low levels of confining stress, and locks at higher levels of confining stress; (2)apparent coupling behavior exists between shear stress and elastic volumetric strain; (3)a set of elliptical plastic potential surface is proposed according to the distribution of plastic flow. An elasto -plastic model is then proposed to characterize the behaviors of the sandstones. Through the simulations of different stress paths for various sandstones, it is found that good agreements arise between the predictions and the experimental results.application/pdf488667 bytesapplication/pdfzh-TW國立臺灣大學土木工程學系暨研究所軟弱砂岩彈塑性模式weak sandstoneelasto-plastic modelreporthttp://ntur.lib.ntu.edu.tw/bitstream/246246/2782/1/902211E002094.pdf