- 期刊
順層岩坡滑動破壞面之粗糙度特徵與尺寸效應
CHARACTERISTICS AND SCALE EFFECT OF JOINT ROUGHNESS COEFFICIENT ON FAILURE PLANES OF CONSEQUENT BEDDING-PARALLEL ROCK SLOPES
摘要
滑動面粗糙度是影響順向坡滑動面抗剪強度的重要參數之一，傳統用於實驗室小尺寸梳尺量測方法不易應用於現地案例尺寸。以台灣新北市烏來區忠治村大規模順層岩坡滑動案例，採用無人機遙測在災後即時建立數值地形模型，計算不同基線長度下裸露滑動面剖面粗糙度係數，探討尺寸效應與異向性特徵。結果顯示空拍量測建立之數值地形模型，可以用於剖面粗糙度係數之量測，適用於不同尺寸等級順層岩坡滑動面，顯示未來可應用無人機空拍測量於全坡面滑動面粗糙度係數計算。除此之外，順層岩坡滑動面常由層面弱面及另一組傾角的節理面弱面所共同組成，形成台階狀滑動面，此台階狀滑動面會引致抗剪強度的異向性。在坡頂的主動區，滑動面由層面與較陡之張裂節理面共同組成，呈現向下跳階現象，其順坡向下坡粗糙度係數會較小於逆坡向上坡；而在坡趾被動區，滑動面由層面與較緩之剪裂節理弱面共同組成，呈現向上跳階現象，故粗糙度係數為順坡向較大於逆坡向，因此建立複合式台階狀順層岩坡滑動異向性特徵模型，以符合真實順層岩坡滑動面粗糙度特徵。
並列摘要
Roughness of sliding plane of dip-slope strata is one of the dominant factors determining the shear strength of rock mass, which is express by joint roughness coefficient (JRC) and measured by using Barton's combs generally. Although traditional methods are useful in laboratory scale, they are not well applicable in situ in large scale. However, the method is not easily used in situ by large-scale. The large-scaled Zhong-zhi landslides in Wulai Dist., New Taipei City, in northern Taiwan are chosen as study objects to be discussed scale effect and anisotropy of JRC. In order to evaluate the above-mentioned effects, different base-line lengths measuring the roughness from the sliding plan morphology in terms of photogrammetry by unmanned aerial vehicle (UAV) after the landslides took place. The JRC can be calculated quantitatively by the photogrammetry, which is applicable for rock slope in different scale. The photogrammetry can be applied in large scale in the future. The sliding plane of dip-slope from top to toe is defined as active, transitional, and resistive zones. The sliding plane in the active zone is composed of bedding plane and steep-angled tension cracks, so the JRC at forward-slope (down-dip) direction is smaller than that at reverseslope direction. The sliding plane in the resistive zone consists of low-angled shear planes and the bedding plane, so the JRC at the down-dip direction is larger than that at the ascending direction. The study demonstrates the photogrammetry is applicable to calculate the JRC of large-scale rock slope, and extends the applicability of scale effect analysis. Besides, an anisotropic roughness model of rock slope with complex-stepped failure mechanism can be established as well.