多功能軟岩沖蝕試驗儀之建立

Abstract

國內尚不存在探討岩床沖蝕的試驗設備，本研究以磨蝕沖蝕 (abrasion)、塊體抽離沖蝕(plucking)為實驗對象，參考國外相關試驗設 備的形式、量測方式、分析方式，整合以後進行沖蝕儀設計與建立。 本研究已完成清水及濁水的水平磨蝕、塊體抽離沖蝕、及高速水 流沖擊等沖蝕機制試驗的基本設計及試驗水槽的組裝，本文目前在水 平向磨蝕試驗方面，細部設計及儀器建立已經完成。水平向磨蝕試驗 的設計主要參考Briaud(1999)的EFA 沖蝕試驗機及試驗程序，將其改 良後並驗證計算試驗管內的的水理情況。本試驗儀的流速範圍為0.54 ∼9.94m/s，試驗分析的解析度可達到0.01mm。本研究並以建置完成 的儀器以進行軟弱岩石的水平向磨蝕試驗。 本研究使用大安溪砂頁岩互層內之砂岩岩心以及人造砂岩來施作 實驗，實驗結果顯示砂頁岩互層中的砂岩在流速0.5∼4.2m/s 之間的沖 蝕率約為0.0225∼0.035mm/hr，砂頁岩互層中的頁岩在流速4.23∼ 9.94m/s 流速之間的沖蝕率約為0.0033∼0.0175mm/hr。 人造沙岩由於其材料顆粒大小不均，沖蝕率會由於較大的顆粒影 響使得沖蝕率有數倍之誤差，在流速0.54∼0.71m/s 之間的沖蝕率約為 20∼220mm/hr 之間

Since there is no erosion equipment for rock specimen in Taiwan, this thesis aims to develop a multi-function erosion equipment for rocks. The existing erosion apparatuses in the world are reviewed first. Then, the basic design of the equipment is finished and the frame of the equipment is also established. The equipment can be used to conduct the erosion test on soft rocks with various erosion types including abrasion, plucking, and scouring caused by high velocity water jet. The abrasion apparatus for clean water is designed in detail and developed in this research. The EFA proposed by Briaud(1999) is refered to establish the apparatus. The developed apparatus can be used to run the abrasion test with the velocity of 0.54 to 9.94 m/s , and its erosion measured precision being 0.01mm. A series of abrasion tests is conducted on core specimens drilled from the uplift section, Da-An river and the block of artificial poorly cemented sandstone. The rock types of specimens at Da-An river include Pliocene sandstone and shale. The experiment results show that erosion rate of sandstone and shale at Da-An river is 0.0225∼0.035mm/hr for the water velocity of 0.5∼4.2m/s and 0.0033∼0.0175mm/hr for the water velocity of 4.23∼9.94m/s, respectively. Due to the poor cementation, the erosion rate of the artificial sandstone, which is 20∼220mm/hr for the velocity of 0.54∼0.71m/s, is higher than the Pliocene rocks.