土壤剪力強度於水平方向空間變異性之初探

Abstract

土壤是一種複雜的天然材料，它的形成由不同地質、環境以及化學過程所組合而成的，這些天然的沉積形成過程，使土壤在垂直及水平方向上的性質存在空間變異性(inherent variabilities)，而本研究要探討土壤水平方向上的空間變異性，所使用的資料類型主要分為三種：(1)基樁載重資料 (2)圓錐貫入試驗(CPT)資料 (3)標準貫入試驗(SPT-N)資料。三種資料會依不同方式處理，將垂直向方向的空間變異性消除，求得垂直向的平均剪力強度，以方便我們探討水平方向上的空間變異性。 前人的研究中，主要會用三種統計模型來描述土壤水平向的空間變異性，分別為Single exponential model、Square exponential model、Fractional Brownian motion model。本研究的目的，先將兩不同地區垂直向平均剪力強度與水平距離之間關係的資料分布情形，將資料依不同類型及水平距離做分類，用最大可能性函數估算法來找出這三種模型的最佳參數與最大可能性函數值，比較三種模型之適用性，找出何種模型相對適合用來描述土壤水平向方向的空間變異性，並利用此模型提供一些案例模擬應用。

Soil is a complicated kind of natural material. It's form basically comes from different kinds of geology, environment, and chemical process. These natural process of deposits made the soil nature exist inherent variabilities, both horizontal and vertical. As we discuss about the horizontal variability of soil in this research, three kinds of data methods listed below are used：(1) Pile load tests data (2) CPT data (3) SPT-N data. These three methods, depending on different processing modes, eliminate the vertical variability, which then receive vertical of average shear strength to help us analysis the horizontal inherent variability. Three statistical models are put to use to describe the horizontal variability of soil in former research, including used Single exponential model、Square exponential mode and Fractional Brownian motion model. The main purpose for this study is to acquire the distribution between the two different average shear strength in vertical and the horizontal distance, classify the data for different type. Using maximum likelihood estimation to find three model’s parameters and likelihood. Compared with three kind of model applicability find what kind of model relatively suitable to describe the horizontal variability of soil shear strength, and provides some case simulation application using this model.