火山岩崩塌地的發生機制與實例

MECHANISM & CASE-HISTORIES OF LANDSLIDES IN VOLCANIC ROCKS TERRAIN

王文能(Wen-Neng WANG)

《鑛冶：中國鑛冶工程學會會刊》 30卷3期 (1986/09) Pp. 131-140

https://doi.org/10.30069/MM.198609_30(3).0015

摘要

本文所稱火山岩崩塌地是指發生在堆積於第三紀岩盤上的火山噴出物之崩塌地。一般而言，火山岩的風化物多具膨脹性，乃係造成火山岩崩塌地的主要基因之一。此外，由於背斜軸部岩石易生張力裂隙，岩石強度低，故有時崩塌地大多會集中發生在背斜軸部附近。龜之瀨崩塌地是日本最著名的火山岩崩塌地之一，凝灰岩風化後的粘土層是造成此崩塌地的主要地質基因；降雨、地下水、與河蝕等是破壞邊坡穩定的誘因。介壽崩塌地與南港崩塌區是臺灣北部兩個標準的火山岩崩塌地。介壽崩塌地內之凝灰岩風化物的粘土層是其地質基因；南港崩塌區的災害基因，除了岩質因素外，背斜的地質構造亦是其一因素。此兩者之災害誘因均為降雨與不當的開挖。

並列摘要

The slope failure caused by weathered products of volcanic rocks overlying Tertiary sedimens is known as landslides in volcanic rocks terrain. Most fresh igneous rocks are generally characterized by high shearing strength. Under some conditions they may be altered to a very soft and plastic clay material, which is one of the worst fundamental causes of landslides in geology. The tension cracks along the crest of an anticline reduce the strength of rocks, therefore, landslides tend to occur along anticlinal axis. The Kamenose landslide is one of the most well-known and typical landslides occurring in the volcanic rocks in Japan. The main shear zone was found in the thin clay layer on top of the tuff. The Chieh-Shou landslide, about 40 km southeast of Taoyuan in northern Taiwan, is underlain by Miocene strata. A clay layer derived from the altered tuff was found about 12m below the landsurface. The clay layer is believed to be closely related to the cause of the landslide. The Nan-Kang landslide area in the southeastern part of Taipei city is actually made up of several ancient or active landslides along an anticlinal axis. The sediments exposed in this area is mainly Miocene sedimentary rocks and tuff. The rainfall and human activities could be the immediate causes of the landslides.