Analysis of Mining-Induced Delayed Surface Subsidence

Abstract

The topic of residual subsidence is important in Europe as it defines possible surface deformation for closed mine areas. It has to be determined because of potential financial claims and damages of sensitive objects such as satellite dishes, precision mechanics objects, agriculture, forestry and hydrogeology, etc. Analyses of measured subsidence after the end of mining exploitation indicate that this process can last from several months to several dozen or even several hundred years, and the final surface subsidence is not known. It is dependent on the individual’s features of excavated medium, depth of exploitation, a system of exploitation, behaviour of surrounding rock masses, etc. In the article, the authors analysed the assessment of the subsidence process after the end of mining operations, based on the innovative method. This concerns the duration of the subsidence process and the size of the expected subsidence. The methodology was applied to the RAG Aktiengesellschaft company project where prognostic calculations were made for seven closed coal mines using unique results of precise height measurements carried out for more than 90 years by the German State Office for National Measurements (Landesvermessungsamt NRW) under the so-called levelling measurements net. These measurements are carried out every 2 years and serve to keep the altitude network in the whole state of Rhineland Westphalia up-to-date. The result of the prognosis for one case study, German mine Auguste-Victoria, is presented in the article.

Calculation Model for Progressive Residual Surface Subsidence above Mined-Out Areas Based on Logistic Time Function

“…Therefore, downward surface movement, sinking velocity, and the acceleration time function should reflect the actual movement of the surface. To study the spatiotemporal distribution of the logistic time function, the first and second derivatives of t can be derived in terms of Equation (5) as Equations ( 20) and ( 21):…”

“…Some objects sensitive to residual subsidence, e.g., resident buildings, railways, or high voltage cable towers, can be unavoidably subjected to impairment, which affects land reutilization, urban planning, as well as foundation stabilization significantly above Energies 2022, 15, 5024 2 of 20 mine-out abandon areas. Therefore, more and more attention from worldwide countries has been drawn to conducting measurements over residual subsidence [5]. In Poland, for instance, it was assumed that the effect ends when the annual increment in subsidence was no more than 10 mm; in Russia, the last series of observations was implemented provided that the overlapping subsidence did not exceed 10 mm within 6 months; while in Germany, it was reportedly up to 3 years before the effect terminated after the end of mining operations.…”

Semi-real time systems for subsidence monitoring in areas affected by underground mining: the example of the Nuraxi-Figus coal district (Sardinia, Italy)

“…According to several authors (Cui et al 2000(Cui et al , 2020Alheib et al 2005;Tajduś et al 2021), subsidence due to longwall mining is structured into three intervals. The first called initial subsidence, is the period when the surface movement lightly starts with low velocity.…”

Prediction Method of Residual Subsidence of Strip Goaf Located in Suburb for Safely Constructing Viaduct

“…It is difficult to maintain the stability of the overlying strata. Under the effort of overlying strata stress, the gaps between the fragments in the under-compacted area are gradually compacted (Blachowski et al, 2018; Tajdus et al, 2021). This action is transmitted to the surface, causing surface residual subsidence. As is shown in Figure 1(a) Part Ⅱ, on both sides of the goaf, one end of the roof is fixed in the rock stratum, which is not easy to collapse, and residual voids are formed on both sides of the goaf.…”