「岩塊體積比」代表併構岩內部岩塊的含量，其為評估併構岩之工程性質的參數。「面積法」為量測岩塊體積比的方法。本研究利用程式模擬面積法的取樣量測，探討取樣範圍大小、岩塊粒徑、岩塊長短軸比及岩塊體積比對取樣結果的影響，並藉由統計學的概念建立數值模式以決定取樣量測之標準差。接著推導出「等值粒徑」的理論，以簡化在取樣範圍內，岩塊粒徑不同的情況。最後利用「信心度」與「信賴區間」的觀念，給予以面積法求取岩塊體積比一定性且定量的描述。 本研究亦施作現地案例，作為數值模式與等值粒徑之觀念的驗證。從驗證結果來看，本研究之數值模式與等值粒徑的理論是正確的。故以面積法量測岩塊體積比時可套用本研究之數值模式及等值粒徑的理論決定岩塊體積比之信賴區間。 The volumetric fraction of block, which is a parameter for assessing the geotechnical properties of bimrock, is the proportion of block included. Areal method is for estimating the volumetric fraction of block. By simulating the areal method for sampling, this research represented the discussion on the influence of sampling area, the diameter of block, the aspect ratio of block and the volumetric fraction of block on the estimated volumetric fraction of block by areal method. With the concept of statistics, this research established numeric model to determine the standard deviation of sampling and the theory of equivalent diameter of blocks to simplify the composite diameters of blocks. The research offers a qualitative and quantitative description of estimating the volumetric fraction of block by the concept of confidence level and confidence interval. In order to check the accuracy of the numeric model and the theory of the equivalent diameter of blocks, several case studies in-situ were conducted. According to the results, the numeric model and the theory of the equivalent diameter of blocks are fairly convincible. As a result, using areal method to determine the confidence interval of the volumetric fraction of block by the numeric model and the theory of the equivalent diameter of block is applicable.
