When conducting environmental and engineering investigations in karst terranes, engineers and geologists often supplement exploratory borehole results with data gathered from surface geophysics to reduce the site-characterization cost and establish the most useful locations for borings or samples. When conducting resistivity investigations, a frequently occurring problem is the need to determine which of the many existing electrode configurations will respond best to the material changes in karst features. Each array has its advantages and disadvantages in terms of depth of investigation, sensitivity to horizontal or vertical variations, and signal strength. In the application presented in this paper, numerical forward modeling was conducted of dipole-dipole, Schlumberger, and Wenner arrays, and they produced markedly different anomaly shapes for a conceptual model of the development of a cover-collapse sinkhole. The resolution of the three above-mentioned arrays was further evaluated along a section of I-70 near Frederick, Maryland, where a sinkhole had occurred in the median of the highway. The image from the dipole-dipole array appeared to be better than those from the Wenner and Schlumerger arrays in displaying the sinkhole collapse area. However, they are all less effective than a mixed array, in which apparent resistivities from all the three arrays are combined and processed together in the model. Because the mixed array requires a significant increase in data collection, the dipole-dipole array appears to be the most effective and less costly configuration in mapping karst hazards areas. This conclusion was then confirmed by two case studies.

No abstract

No abstract

No abstract

No abstract

In 2012, China's State Administration of Coal Mine Safety conducted a reconnaissance and statistical analysis to better understand and characterize water inrush accidents in China's coal mines. Data collected from 12,985 mines from 26 provinces and municipalities were used to study each mine's hydrogeological classification, water content coefficient, and the level of effort being spent in preventing and controlling these accidents. Analysis of the water inrush accidents in these mines suggests that their likelihood reflects a mine's hydrogeological characteristics, and that they can be controlled by professionals who are specifically trained for mine water prevention and emergency responses. In terms of hydrogeological complexity, there were 78 extremely complex coal mines, 827 complex mines, 4141 moderately complex mines, and 6458 relatively simple mines. Advances in mine water control and management methods and techniques and implementation of safety standards and regulations have significantly reduced the number of people killed per ton of coal produced, but analysis of the 2013 water hazard accidents indicates that continued effort is needed to better understand hydrogeological classification and implement safe procedures in water prospecting and dewatering.

No abstract

No abstract