Abstract

A legacy of environmental challenges with abandoned mines remains for many generations. The challenges include among others: (i) danger from sinkholes above shallow old mine workings and (ii) effects of rising water level in deep mines. Abandoned shallow mines show after > 20 years no damaging subsidence. Sinkholes, however, may still develop by structurally controlled failure. Main contributing factors are the geometry of an underground opening. Geological factors include the resource type (orebody or seam), height of rock overburden and cohesive soil, water flow and discontinuity spacing. The latter determines the bulking factor of the displaced roof and thus the maximum caving height. For steeply inclined openings it must be considered whether the caved rock moves down the dip and prevents self-stabilization. Rising water levels in deep abandoned mines may induce seismic events. Despite significant progress in monitoring and numerical methods there is still no appropriate geological or rock mechanical basis for explaining or predicting water pressure induced seismic events. Some research topics are suggested to approach this issue.

Introduction

The typical life-cycle phases of an underground mine encompass exploration and discovery – feasibility and construction – mining and extraction – closure and site rehabilitation. While mining is accepted in broad terms – if you cannot grow it, you have to mine it – it is often challenged on the individual mining project level. During mining, there is added value due to jobs, manufacturing and often prosperity. The negative impact on the environment was countered by improved environmental standards and the slow acceptance of sustainability as well as improvement of miner’s health and safety led to an increased social license to mining operations. The regulation about ownership of minerals is important for all mining phases. The first mining law originated in 1185, which stated that minerals were at the king’s disposal, later that right was transferred to the nobility. Two different views of ownership developed then. In German-speaking countries, the owner of land owns only the surface minerals. In English speaking countries the owner of the land owns the minerals to indefinite depth. Some exemptions to those rules for strategic minerals are still in order. Particularly coal mining in the Ruhr area led to the first mining law in 1865 by the Prussians. They made the mining company responsible for damages at the third party property and pay compensation had to be executed. Different institutions such as arbitration boards and finally mining authorities developed over time. Any younger legislation in Germany followed this Prussian mining law. In essence, mining companies are liable for loss or injury of men as well as property damage due to mining and abandoned mines, and accruals must be established.

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