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Down-hole acoustic televiewer (ATV logging) is a geophysical well-logging device known to be able to reveal underground in-depth image. However, reviewing the current developments in the area of geotechnical engineering, ATV logging data were predominantly used for the purpose of visualizing and calculating the specific structural features in an open borehole, and nothing more. Noticeably, to the majority of engineering applications, it appears that ATV logging played a minor role compared to other geophysical borehole logging tools. Our study does not take it for granted. A systematic study is presented of the significance and consequent applications of ATV logging. The significance of correlation between acoustic amplitude and different geotechnical parameters is discussed and found to be consistent with previous findings. The result tells that ATV logging is actually able to provide timely and ground-truth information during site characterization, if properly used. Additionally, in our study, a simple rock mass evaluation index, Aco-RQD, is proposed, which is applicable to all aspects of geotechnical engineering as long as the continuous ATV logging data are available.

Drought and landslide are two common hazards that occurred in mountainous regions of Taiwan. This study is intended to develop a new concept of hazard prevention and management for solving both hazards simultaneously, in which the complex hazard has increased over the years in intensity and frequency due to climate variability and change. The proposed concept is a win–win solution that contains the feature of efficiency to mitigate two hazards together. When pumping groundwater as daily water demand at landslide-prone sites, the pore-water pressure decreases and the thickness of the unsaturated zone increases, which can result in stabilizing landslide-prone slopes and increasing flood storage capacity as an underground detention basin, respectively. Consequently, this approach can reduce the risk induced by the two hazards. To reinforce the effectiveness and instantaneity of hazard management, the technologies of smart sensing, smart transmission, and smart computing are then incorporated into a novel framework to develop an intelligent hazard prevention and management system. Thus, the groundwater supply-slope stability management system was installed and tested in the remote Kaoshi tribe, which is situated in Kaoshi Village of Mudan Township, Pingtung County, southern Taiwan. Hydrogeological issues for subsurface complexity, field investigations, and numerical modelling for preliminary evaluation and system design are also highlighted in this study. The developed system, which can offer valuable support for decision-making processes of hazard prevention, is capable of monitoring dynamic signals from various in-situ sensors, helping water resource allocations, and stabilizing hill slopes by means of drainage.

A simple and efficient improvement on the conventional packer testing technique is described. Based on experience associated with hundreds of packer tests in the past decade, a functional change is proposed with respect to the pressure inflation supply for the packer testing unit. The change involves allowing each packer to be independently controlled with two separate gas-flow delivery systems, allowing for independent inflation and decompression underground. Four types of packer set-up are presented, which are able to be used alternately, according to specific environmental needs. It is believed that this is a small but important technical solution for packer testing failures, particularly as regards low water-level conditions in the well, regardless of whether this is a natural effect or a result of the drilling operation.

A simple descriptive-statistical approach is proposed for evaluating the transmissivity of fractured-bedrock under field conditions. Based on standard well logging and identification of structural discontinuities from borehole televiewer, the approach consists of four steps: (1) determination of discontinuity properties, namely the frequency of discontinuities and the ratio of open fractures along the borehole; (2) ranking the three well logs and the discontinuity properties into tertiles (high-to-low); (3) performing statistical analysis (F-test) for the three well logs to assess the significance of open fractures on the water-transmitting potential and then assigned a weighting factor; and (4) a semi-quantitative indicator, RGVFO, is obtained by multiplying all predictive indexes and weighting factors. It is a multi-criteria evaluation procedure that elucidates the quantitative and qualitative importance of all selected geophysical indexes. A high cross-correlation between transmissivity to RGVFO value is found, which indicates that by a combined consideration of well logging and structural discontinuities, an appropriate estimate of bedrock water-transmitting potential can be derived.

The feasibility of using geological and geophysical well-log and borehole-televiewer data for the identification of hydraulically transmissive fractures is evaluated. Twenty-nine boreholes were drilled to a depth of 100 m in the middle-stream basin of Jhuoshuei River, Taiwan. Four criteria that assist in indicating the potential presence of permeable zones are proposed, including: lower gamma-ray response compared with the average response, divergence of the short normal-resistivity log relative to that of the long one, longer sonic travel time, and the appearance of discernible openings detected with the televiewer. With these, the transmissivities at the predetermined depths were estimated and verified by an in-situ hydraulic test. The statistical results indicate that, particularly in the mountainous area where a complex folded structure with a succession of synclines and anticlines is shown, the interpretation of lithologic conditions is not necessary to identify the presence of a relatively higher-permeability zone. Comparatively, the estimates of porosity and fracture aperture are the necessary premises to the prediction of hydraulically transmissive fractures. A joint consideration of all four criteria is found, allowing a less biased evaluation of the fracture transmissivity.