英文篇名
APPLICATIONS OF GEOPHYSICAL TECHNIQUES IN LANDSLIDE AND UNDERGROUND CAVITY INVESTIGATION
作者
張濟權
摘要
由於台灣山多、雨多、地震多、以及煤田採掘後所遺留的地下坑洞,而潛伏了有隨時發生崩塌及沈陷災變的可能,因這些災變的發生將對人工結構物諸如水壩、公路、橋樑、住宅、電廠...等產生破壞,造成無法彌補的生命財產損失。是以如何在工程建設之初,作好周詳的工程基址調查,以杜絕此崩塌及坑洞下陷所衍生的災變,為一刻不容緩的重要工作。崩塌地的調查在道路、水庫、社區開發、隧道...等工程上是非常重要的,其調查的項目包含了崩塌的形式、規模、滑動面、地下水狀況、崩塌地發生原因及誘因。使用的調查方法則有地形、地質、地球物理、鑽探及岩石土壤物性試驗等方式來進行。地球物理為其中之一不可欠缺的調查方法,它主要係提供崩塌地的幾何形狀,地質構造及岩性物理特性資料。常用之地球物理方法為折射震測法及直流電阻法兩種。於坑洞的調查中,地球物理主要是應用於坑洞和其周邊介質在物理特性如密度、電阻、彈性波速度等有強烈對比的差異,使用地表地電阻法、震測法、重力法及井孔對井孔、井孔對地表、地表對井孔、單一井孔的重力、電阻法、震測法,電磁波法來偵測此異常並判釋坑洞的位置、大小、形狀。本文主要對地球物理在崩塌地及坑洞的調查所可能應用之方法、原理及實例作一概括性的介紹,以供工程地質界的參考。
英文摘要
This paper introduces some principles and case studies of the geophysical techniques in landslide and underground cavity investigation. On landslide investigation we can apply the geophysical methods to solve the following problems:(1)Determination of the geometry of landslide and its water saturation,(2)Assessment the physical properties and states of rock comprising the landslide, and(3)A study of the motion of landslide mass. According to these results and other informations such as drilling, geology ......etc., civil engineers are able to design some special remedial actions to control and prevent landslide occurence. Because a cavity in the ground can be very threatening to the safety of structures, such as buildings, dams, power plants ......etc., the detecting and mapping of cavities is very important in site investigation phase. Since the cavity and surrounding geological material has relatively high physical contrast to normal ground, therefore, we can apply a variety of special geophysical techniques on the surface or in the borehole to measure the abnormalities and find out the location, shape and size of a hiding cavity. Finally, we can use drilling techniques to verify and modify these results to obtain exact locations of cavities. Above of all, civil engineers can thus take some special remedial measures or reorganize the construction plan to deal with this problem.