Identification of Geotechnical Conditions in Areas of Former Shallow Mining Activity Using Geoelectrical Methods

Abstract

The inconvenient sinkholes in the area of the village of Kuźnica Masłońska were observed in last years. In the past, shallow exploitation of the Lower Jurassic brown coal was conducted in the vicinity of the village. The principal purpose of the study was to explain the origin of the deformations and to define the geotechnical conditions for building foundation. Geoelectrical investigations (resistivity and induced polarization imaging) and geotechnical identification were performed. Our identification showed the existence of a low resistive vertical zone near the surface, which is not connected with clayey sediments. According to geoelectrical measurements, this zone could be interpreted as a region of increased porosity and enhanced water infiltration. The region is connected with the former shaft. The geotechnical investigations pointed to unfavourable conditions caused by the existence of non-load-bearing beds and an intensive process of suffusion. The conclusion about the partially post-mining character of the observed sinkholes intensified by adverse geological features and processes can be accepted.