TXT-tool 4.081-9.1: Rotary Sampling Drilling Technology to Extract High-Quality Cores Using a Sleeve-Incorporating Core Barrel and Polymer Mud in Landslide Areas of Japan and Vietnam

In many cases, cores that are extracted from landslide areas contain loose, moving land blocks and crushed rock that differ from their in situ state because of disturbance at the time of drilling. Therefore, it is difficult to obtain much of the information required for analysis of landslide mechanisms. In recent years, a rotary drilling technology in which a core barrel incorporating a plastic film and diamond bit has been used in Japanese landslide areas, along with polymer mud as the drilling fluid. This drilling technology is effective in maintaining the core hole wall in soft layers, such as gravel mixed with soil, and has made it possible to eliminate cutting in many cases. As a result, it has become possible to extract high-quality cores from depths of 200 m or more in landslide areas and to obtain the information needed to analyze landslide mechanisms, such as the slide surface and the record of landslide movements and activity, as well as the geological features, during the initial stage of investigation. We studied the feasibility of this drilling method, which is highly dependent on the experience and judgment of veteran drilling engineers, the adaptability of the method to landslide areas other than those in Japan, and the economic efficiency of the method in comparison to the conventional drilling method.