硬頁岩之張力行為

Abstract

本研究嘗試利用自行設計之直接張力夾具進行單軸直接張力試驗，以探討 橫向等向性岩石之張力行為 ( 破壞型態、強度特性及彈性係數等 )。嘗 試對具有橫向等向特性硬頁岩的直接張力強度與變形特性做一探討。從一 系列之試驗結果顯示，硬頁岩單軸張力強度隨層面角的增加而增加，且高 低角度之張力強度差異很大。至於變形性研究利用以二個不同傾角圓柱試 體，至於變形性研究利用以二個不同傾角圓柱試體，其中一個為θ等於 90度 經過一系列試驗，得知乾溝層硬頁岩之單軸張力試驗所得的五個彈 性常數 E = 58.09GPa、E' = 47.98GPa、v = 0.217、v' = 0.23、G' = 19.66GPa高於單軸壓力試驗 E = 51.82GPa、E' = 34.76GPa、v = 0.192、 v' = 0.172、G' = 12.81GPa ，此乃因單軸壓力試驗前段為試體 裂縫閉合段其應變較大，故有較低的彈性模數；在層面角θ等於 75°試 體破壞階段前，有體積減小現象；試體破壞模式得知θ等於 75度與 90° 試體破壞不會沿層面破壞，會橫切過試體層面，且有鋸齒狀破壞面，而θ 等於 0°、15°、30°、45°、60°試體會沿層面破壞.對於硬頁岩之單 軸張力強度，本研究透過一些學者所提出的強度準則與試驗結果作比較， 結果大致符合。本研究並提出修正Nova單軸張力強度準則，將凝聚性強 度 C 與岩石之內摩擦角φ隨試體層面角β變化。 In order to investigate the tensile behavior of anisotropic rock,a verified tensile gripping equipment is developed; a series of direct tensile test is performed on the core samples of argillite exhibiting transversely isotropic properties ; and the very small lateral strain of the specimens ismeasured by a special arrangement of electric resistance strain gauges, andsemicoductor strain gauges during the testing. The 5 elasticconstants of argillite in tension are calculated from themeasured data of two specimens with different inclination of the foliation planes with respect to the loading direction. The mean elastic constants E= 58.09GPa,v=0.217are obtained from the argillite specimens with 90 degrees inclination angle and E'=47.98GPa,G'=19.66GPa, and v'=0.23 are deduced from the argillite specimens with the inclination angle of 30, 45 and 60 degrees. The final failure plane of specimen occurs along the foliation planes for the specimens with the inclination angle of 0, 15, 30, 45, and 60 degrees, but the failure planeshows a sawtoothed mode for the specimens, which fail partly along and partly cross the foliation planes, with the inclination angle of 75 and 90 degrees.