At present in China, the use of the transient electromagnetic method
(TEM) is emerging as a leading geophysical technique for exploration of
water-filled zones in coal mines. These zones are more conductive than the
host coal and are easy targets to map. However, there is a growing interest
for the investigations of double-layered or multi-layered mined-out zones.
Therefore, it is necessary to study the feasibility of TEM's abilities to
detect double-layered, water-filled voids. In this study, the basic
hydrogeological conditions of a survey area, located in the northern China,
are described. The corresponding geophysical models of the single- and
double-layered water-filled zones are developed from borehole logging data.
Then, forward calculations of different models are carried out with 1D
numerical simulations. The modeling results show that it is feasible for TEM
to identify these types of targets under certain conditions, including
instrument sensitivity, low resistivity for the water-filled zones, and
shallower depths. Moreover, the field survey for locating double-layered
water-filled zones in coal mines in the Datong region of Shanxi Province is
verified by well drilling.
Slope failure mechanism affected by mining subsidence: a case study of highway slopes in Yangquan, Shanxi Province, China
