巨觀等向性混成岩製作表面影像與力學性質; The fabrication,surface images and mechanical properties of macroscopically isotropic Melanges

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Title:	巨觀等向性混成岩製作表面影像與力學性質;The fabrication,surface images and mechanical properties of macroscopically isotropic Melanges
Authors:	蔡文傑;Wen-Chieh Tsai
Contributors:	土木工程研究所
Keywords:	巨觀等向性;併構岩;混成岩;Mélanges;Macroscopically isotropic;volumetric fraction;bimrock
Date:	2003-07-07
Issue Date:	2009-09-18 17:13:09 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	摘要混成岩為泥質填充物夾著許多外來岩塊或岩屑所組成，本文利用人造方式製作具有不同體積比之『巨觀等向性』混成岩試體，以探討混成岩中岩塊體積比例對整體力學性質之影響。因岩塊體積比是最常用來估計混成岩整體工程性質的參數，本文利用旋轉式掃描器快速擷取試體表面影像，再以中分法(Dividing Method)及SimplePCI影像處理法估算岩塊之體積比，並與傳統之單位重法加以比較，結果顯示，在中、高體積比(31%、46%、58%)時，皆有良好之一致性，在低體積比(16%)時影像處理法則提供較單位重法為佳的精度，且量測結果不受試體內部含水狀態之影響。本文並以幾何理論推導單一粒徑岩塊與平面剖面之外視粒徑分佈及圓柱剖面之等值平均粒徑分佈關係。從本研究所建立之前述關係可由試體內部岩塊之粒徑分佈推求平面剖面及圓柱剖面之粒徑分佈。亦可由平面剖面及圓柱剖面之粒徑分佈反求試體內部岩塊之粒徑及其分佈。圍壓由低至高增加，材料之破壞機制由岩塊與基質材料界面之破壞轉由岩塊與基質材料的強度來控制。混成岩在岩塊體積體比（0~46%）時，凝聚力隨體積比之增加而減少；內摩擦角隨體積比之增加而增加。利用微分模式預測楊氏模數與體積比之關係，在圍壓12MPa時經與實驗結果比較趨勢相當吻合，且楊氏模數與體積比之關係接近Reuss下限邊界。 Abstract Mélanges - A mappable body of rock that includes fragments and blocks of all size, both exotic and native, embedded in a fragmented and generally sheared matrix. Although Mélanges or bimrocks are heterogeneous in microscopic scale, it is more practical to replace them by “equivalent homogeneous medium” in most geotechnical engineering scale. The preparation technique for synthetic mélanges which overall mechanical properties are isotropic has been developed. According to the concept of stereology, this thesis used a rotary scanner to catch the cylindrical surface images of mélange or bimrocks. The thesis uses cylindrical surface and planar images to measure the block volumetric fraction. The block volumetric fraction measured by Simple PCI , Dividing Method and unit weight method are similar to actual volumetric fraction (31%, 46%,58%). Simple PCI and Dividing Method can accurately measure the low block volumetric fraction (16%). The image process method of measuring block volumetric fraction is stable when the water content of specimen changes. In addiction, this thesis derived relationships between the apparent block diameter and the cumulative block apparent percentage for cylindrical surface and planar images. Furthermore, actual block size and distribution can also be measured by this concept. Failure mechanism of Macroscopically isotropic Mélanges is from block-matrix contact failure to both matrix and block compression with confining pressure increasing. Increasing the block volumetric fraction (0~46%) decreased the cohesion and increased the internal friction of Mélanges. Using Differential scheme to predict the relationship between tangent Young’s modulus and block volumetric fraction, at confining pressure is 12MPa the tendency of test is similar to the Differential scheme and the value is close to Reuss lower bound.
Appears in Collections:	[Graduate Institute of Civil Engineering] Electronic Thesis & Dissertation

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