不同尺度山崩潛感圖製作方法之研究

Abstract

本研究目標定位在不同尺度山崩潛感圖製作，選定田古爾溪集水區流域板岩地區為研究區，探討岩坡在不同比例尺圖面下，其可能破壞類型，並且建立山崩潛感圖製作之方法學。不同比例尺的圖資須對映到不同尺度的斜坡單元。五萬分之一地質圖，表示距離至少500公尺要有1個位態資料。按其精度，平均面積25公頃決定一個斜坡單元大小，但就一個25公頃的斜坡單元面積，其內部的坡向、位態資料差異性仍大，所以還無法完整闡釋出一個邊坡的破壞類型，加上板岩邊坡的破壞，除了受到重力潛變影響之外，節理弱面也尤其重要，因此考量到大比例尺工程地質圖的製作與未來工程規劃設計，本研究選擇田古爾溪下游與蘭陽溪匯流口處兩側小尺度邊坡進行分析研究，欲找到現地最小斜坡單元，了解其真實破壞情形，作為與大尺度邊坡的一個相對比較。 斜坡單元以物件式影像分析軟體eCognition產製，並藉軟體本身規則集建立一套分割流程，比較過去自動產製斜坡單元之相關研究，最大不同在於一開始輸入的一級河集水區框架圖層，是以天空開闊度圖輔助完成，因天空開闊度圖可依不同解析度的數值地形高程模型（Digital Terrain Model），很快的判釋出其各別明顯的水系和山稜線，大幅減少在地理資訊系統軟體調整水系門檻值與產製集水區框架之後的編修時間。為了能明確掌握現地邊坡破壞情況，自行布設2016年田古爾溪出水口兩側裸露坡面上之控制點，且架設全測站經緯儀測量所有座標點位，以UAV拍攝方式，產製出高解析度數值地表模型（Digital Surface Model）。 比較網格資料5m乘以5m的DTM，和自行產製高解析度的DSM，以物件式影像分析方法分別產製田古爾溪下游區的斜坡單元，且選擇兩處代表性地方，探討不同解析度數值地形高程的能力限制，最後展示4張不同比例尺圖資內容，其比例尺分別為1/50000、1/25000、1/5000、和1/1000。

The research aim is the manufacturing of potential map in different criterion of slope stability in the Tian Gul Creek Basin slate region. The research is based on possible failure types under different scale plan of slope, and establishes methodology of map production. A 1/50000 geological map means that every 500 meters of distance should consist of one state. Based on its resolution, the average area 25 hectares decides the size of a slope unit. However, as a 25-hectare slope unit area, its internal aspect and state information still show a great deal of differences, thus cannot fully explain the type of a slope failure. Moreover, the damage of slate slope is influenced by the gravitational creep and the plane of weakness on the joint. Hence, considering the making of large-scale engineering geology map along with the future project planning and design, this research chose a micro-scale slope to analyze, in hope to find the actual damage condition of the smallest slope unit for future reference. Object Oriented Analysis software eCognition that produces slope unit in object form compares past correlate researches with the result by segmentation process built by its own rules. Sky-view map inputs one-river watershed frame layer in the beginning, and it is the biggest difference of all. Since the large reduction of time that river thresholds and build watershed frame from Geographic Information System (GIS) results from Sky-View map, we can tell the distinction of the water system and ridge line from the DTM in different resolution. In order to understand the destruction of slope, GCPS on the two sides of the slopes was built in 2016 and DSM was produced by UAV completed by point coordinates token from total station. The 5m DTM and self-made DSM were compared to create the downstream of Tian Gul Creek based on Object Oriented Analysis. Then the two parts of representative were chosen to find out the different resolution. Finally, the four different scales were displayed, namely 1/50000, 1/25000, 1/5000 and 1/1000.