Geotechnical Characterization of Fine-Grained Spoil Material from Surface Coal Mines

Abstract

Coal mines produce large amounts of excavated waste soils, known as spoils. These materials can cover vast areas, are typically dumped in heaps without any treatment and are difficult to exploit for engineering purposes because of their significant variability. Efficient exploitation of spoil heaps poses engineering challenges, related mainly to the involved degree of uncertainty. A small number of studies have attempted to characterize the geotechnical properties of spoil material; however, there remains a considerable gap in understanding how to deal with spoil materials in the context of sustainable development and civil infrastructure design. In this work, a systematic effort is made to quantify the uncertainty of the geotechnical properties of a particular spoil heap. Laboratory test results based on an extended investigation of a spoil material originating from lignite coal mines are gathered in one database and thoroughly analyzed. The results reveal and quantify the significant spoil material variability, which is contrasted against data for common soils, while a systematic approach is proposed for spoil material characterization.

3D Numerical Analysis for the Valorization Potential of Spoil Heaps by Shallow Foundations

“…Nevertheless, the soil mass was considered one unified spoil material with significant uncertainty for practical purposes in the analysis. This assumption was analyzed in-depth by Zevgolis et al [16] and was based on extended experimental results. Very briefly, in the spoil heap, a great variety of soil types appear in a spatially random arrangement.…”

“…These are typical reclamation options for many types of spoil heaps globally, and this work presents an initial examination of their implementation. A massive spoil heap, whose geotechnical properties have been systematically analyzed in the past [16], was employed as a reference for the analysis. Overall, this work aims to answer whether heaps of lignite mines, such as the spoil heap under investigation, can be used for wind turbines as renewable energy projects, buildings needed for several valorization plans, or other infrastructure, by employing shallow foundation systems.…”

Slope stability of deep surface coal mines in the presence of a weak zone

“…In a recent research study, Theocharis et al (2021) organised and presented a large geotechnical database collected from various boreholes in several Greek lignite mines.…”

“…The weak zone was simulated as a 5m thick horizontal soil layer. For the overburden soil, the mean values of Theocharis et al (2021) for the friction angle (φ=28°) and cohesion (c=185kPa) were used. The weak zone was assigned significantly reduced strength parameters with respect to the overburden material, presumed to be the zone's residual strength.…”

“…COV[φz]=20% and 30%. Both values are typical for friction angle and comply with Zevgolis et al (2021). Therefore, SF is a function of one independent variable; for comparison purposes, SF is assumed to be both normally and lognormally distributed.…”