| 摘要: | 本研究搜集台灣西南沿海地區之鑽探資料，利用空間插值法推估西南沿海地區的土層性質分佈，並經過經驗公式將SPT-N值轉換為各種工程參數，以了解西南沿海地區的土壤工程性質分佈狀況。另外，藉由各種鬆軟地盤之判斷準則，分析西南地區之鬆軟地層分佈。其中，除利用「單一準則」進行鬆軟地盤判斷外，尚將目前常見之幾種鬆軟地盤準則（N值、含水量、鬆軟土層厚度）整合，進行「多重式準則」的多重判斷，最後將西南沿海地區的地盤鬆軟程度分級，並繪製成鬆軟地質分區圖以供使用參考。
研究結果如下：(1)本文所搜集各縣市之鑽探資料大致分佈狀況如後：彰化縣與雲林縣較為均佈，嘉義以南的縣市多在於沿海處，台中縣則為集中於南區。(2)利用N值可簡易快速判定鬆軟地盤位置，但該鬆軟土層厚度卻可能很薄，顯見利用單一準則判定可能會有偏差。(3)將鬆軟土壤分佈與地形變遷資料比對後，發現歷史記載有地形變遷處確有N值較低、含水量高、鬆軟土壤厚度大等鬆軟土壤之特性，顯示兩者間的關係密切。(4)西南部七縣市中，現代沖積層範圍內的土層N值大部份都小於10，或甚至低於4，地質相當鬆軟，其分佈範圍大致在南二高之西側。(5)綜合多種判定準則（根據Nmin值、最高含水量及鬆軟土層厚度）後進行評估得知：雲林縣麥寮鄉、土庫鎮的地盤分區被列為III級鬆軟地盤（極鬆軟），顯示經過鬆軟地盤判斷準則多重判定之方式具一定參考性。
This research integrates the borehole data of the south-west coastal area of Taiwan to analyze soil properties. First, this borehole data estimates the soil properties of the south-west coastal area in Taiwan with space Interpolation. Second, it’s easier to realize the distribution of soil engineering properties with the method of transferring SPT-N value to Engineering parameters by empirical formula. In addition, we can discriminate soft ground from south-west area of Taiwan with several criterion of soft ground. Most of all, this study combines SPT-N value, water content, and thickness of soft soil, three criterion, to classify ground based on different level of soft soil. As a result, it leads to new pictures of different level of soft ground for reference.
The following are the main result:
(1) The borehole data of this study indicates its rough distribution of Taiwan as below: Changhua and Yunlin are well mixed; Chiayi, Tainan, Kaohsiung, and Pingtung are concentrated on coastal area; Taichung on south area.
(2) We can tell where the soft ground is quickly by SPT-N value only, but it’s still not precise.
(3) The area with landform changes have these three characteristics: lower SPT-N value, higher water content, and the thickness of soft ground.
(4) The majority of SPT-N values of soil in alluvium are smaller than ten, or even lower than four. That means the soil in alluvium is extremely soft.
(5) This research is of great worth for combining with three criterion of soft ground, SPT-N value, water content, and thickness of soft soil to analyze the ground of two towns (Mailiao and Tuku) of Yulin and verify the soft ground level correspond to actual situation absolutely. |
