Abstract: A proposed project site is at the typical mined-out area of the clay mineral in Zhangqiu District of Jinan. Within the project limits, there are two clay mining sites that had a production period between 1999 and 2014. The mine layer called Layer B was the top of the Permian Shihezi Formation. So, it is critical to identify the distribution range and scale of the mined-out area and to treat it appropriately before the construction. Based on a geological study of the mining area, the geophysical prospecting by using magnetotelluric sounding and exploratory drilling to verify the depth section of the goaf distribution and delineate the plane range for treatment were successfully implemented. A 60-meter survey line was located on both the east and west sides for the magnetotelluric sounding. Then three (3) boreholes were drilled for the verification. According to the Technical Code, the grouting system, in which the treatment area of mined-out area, the amount of work and the injection pressure were determined. The technical workflow and the experience of this project have some applicability in the treatment of the mined-out area extracted from the clay minerals and from the small mines.

Key words: Clay Mineral, Mined-out Area, Magnetotelluric Sounding, Exploratory Drilling, Grouting Treatment