Full-scale field experimentation of a new technique for protecting mudstone slopes, Taiwan

This paper documents a full-scale field experimentation of a new technique, called ''green coating'', for protecting steep ''mudstone'' slopes. Mudstone is a weak sedimentary rock, formed during Miocene to Pliocene and Pleistocene. Many forms of geologic damage such as erosion, mudflow and slope failure are often seen in the mudstone area during the rainy season. This poses a great challenge to geotechnical engineers in Taiwan, as many large construction projects such as the Second National Expressway and the High Speed Railway are set to be constructed through the mudstone area. The held experiment is intended for validating the new technique which has evolved from experience generated from research projects conducted over the past decade. The new technique involves the use of two types of waterproof materials. One material is asphalt, and the other is geotextile sheets coated with asphalt. A mudstone hill is selected for treatment by the new technique. The total surface area of the cut slopes treated with the ''green coating'' technique is about 630 m(2). Engineering details of the treatment are presented in this paper. Two types of measurement are made to observe the movement and the inclination of the treated slopes. Based on the field observations and measurements, the treated slopes do not show any signs of significant erosion and movement. Thus, the new technique has been demonstrated to be an effective means for preventing erosion and failure of the mudstone slopes.