鄭富書2006-07-252018-07-092006-07-252018-07-092003http://ntur.lib.ntu.edu.tw//handle/246246/2801台灣西部麓山帶岩石之膠結及壓 密程度不佳，復以台灣地區多雨水， 既溫且濕的氣候環境，故岩石強度不 高且易風化。當隧道開挖後，隧道周 圍岩石極易因浸水弱化導致隧道周圍 塑性區變大，產生擠壓現象的依時變 形災害。本研究以五指山層砂岩、木 山層砂岩、大寮層砂岩等三種岩層為 研究對象，探討其遇水弱化及潛變之 力學行為。透過一系列單軸潛變及不 同體積應力條件下之三軸潛變實驗結 果，探討其破壞包絡線及潛變行為。 單軸潛變實驗結果顯示木山層於 低應力下的潛變行為異於五指山層及 大寮層砂岩，其第一階段的軸向潛變 量通常會大於第二階段，之後軸向潛 變量又會隨著應力比值的增加而變 大。 傳統三軸潛變實驗結果顯示，木 山層砂岩軸向與環向潛變量隨軸差應 力的增加而呈單調遞增的趨勢，且將 軸差應力正規化至應力比後，各不同 圍壓之結果，有相當一致之趨勢。在 含水量影響方面，相同應力比下，含 水試體之潛變量均較乾燥試體來的 大。在體積變形方面，乾燥試體在圍 壓為零時，應力比低時，體積呈壓縮 狀態，當應力比大於0.5 後，開始有體 積膨脹的情形發生；圍壓逐漸升高 後，體積變形則大部份處於壓縮狀 態。含水試體則不論圍壓為何，均大 部份處於體積膨脹之狀態。在破壞強 度方面，實驗結果顯示木山層砂岩為 一高度遇水弱化之砂岩，其強度弱化 比約為40%。 木山層砂岩傳統三軸及純剪三軸 之潛變試驗結果顯示，體積應力階段 時，圍壓大於10MPa，軸向與環向潛 變量相當一致，顯示木山層係一均向 性高的材料。相同應力狀態下，純剪 三軸應力路徑所得潛變量均高於傳統 三軸的試體。In the western Taiwan most rocks are sedimentary rocks of tertiary period. These rocks are often not well cemented, and sometimes full of geological structure, such as joint, faults, fracture. Besides, rainfalls in Taiwan often exceeds thousands of millimeter, rock in this situation may weathered very quickly, and may cause many engineering problems. In order to reduce the problems encountered during engineering, we must research the mechanical behavior of these rock. In this study, we research the creep behavior of sandstone, included three rock strata. Uniaxial and triaxial creep 2 tests are used to study the creep behavior sandstone. The effective of stress path and level of shear stress and confining pressure were investigated. The uniaxial creep test results indicate that sandstone has the following creeping behavior: In Mushan sandstone, the primary axial creep behavior is significant at low level of shear stress. In Mushan, creep strain is large at the initial step and reduces rapidly at the second step. Nevertheless, in overall situation greater degree of shear stress will induce greater creep strain. According to the conventional triaxial creep test results, the creep strain and creep strain rate increase with deviatoric stress. And if we normalize the deviatoric stress to SSR (Stress - Strength Ratio), we found that in the SSR ε− diagram, every curve has the same trend, and falls in a very narrow region, in spite of confining pressure. In this study, we also found that in the same SSR the strain of wet specimens always greater than dry specimens. In the volume strain of wet specimens, the volume always dilates at every SSR. the strength of sandstones decreased with water. In the hydrostatic creep test, when cell pressure is higher than 10 MPa, the axial creep behavior and laterial creep behavior are similar. the amount of lateral and volumetric creep during the pure shear stress path creep test is higher than during the tradition triaxial test at the same stress level.application/pdf145070 bytesapplication/pdfzh-TW國立臺灣大學土木工程學系暨研究所砂岩潛變sandstonecreepreporthttp://ntur.lib.ntu.edu.tw/bitstream/246246/2801/1/912211E002046.pdf