大地比電阻法應用於溪頭大學坑崩塌地之調查

Abstract

本研究於台大實驗林溪頭營林區大學坑，以地電阻法進行崩塌地調查，由比電阻值、地層厚度對崩塌地的地質構造，與地層的含水狀況作估探，並利用測線電極排列的偏移誤差，調查淺層地質的不均勻性。研究成果如下： 一、 由比電阻剖面的分析，可以觀察到崩積層不連續、鬆散的堆積構造。 二、 在乾季或濕季探測，大學坑地表下皆有低比電阻體的存在，可能是伏流水或是黏土層，都可能在大雨來臨時，因入滲補助、棲止水相互連結而破壞穩定的狀態。 三、 由上游至下游的探測，由比電阻與偏移誤差可觀察到土石流崩積層堆積的分佈狀況。 四、 本區偏移誤差較大，顯示淺層地質不均勻，地電阻法探測易受影響。

The aim of this study is to investigate the colluvium characteristics using electric resistivity method at University gulley in Chitou. The resistivities and the layer depths can figure the geological and hydraulic condition in this area. The offset errors by the arranged arrays can estimate the lateral resistivity effects in the landslide site. The findings are as follows: 1. Analyzing the resistivity tomography, the accumulated composition in the colluvium is discontinuous and loose. 2. The low resistivity layers, says the subsurface flow or clay layers, found in dry and wet periods may endanger this site in the rain seasons. 3. Investigating from the upper to the lower slopes, the resistivity tomographies and the offset errors show the geological characteristics of debris flow. 4. The offset errors indicate the influence of the heterogenic to the survey is large.