Numerical simulation on mining-induced water inrushes related to geologic structures using a damage-based hydromechanical model

A large number of statistics indicate that water inrush has a direct relationship with geological structures such as fault and karst collapse columns. Understanding the mechanism of water inrushes controlled by geologic structures is of vital importance for adopting effective measures to prevent their occurrence. The work begins with formulization of a damage-based hydromechanical model based on elastic damage theory. Next, the model is numerically implemented with finite element method by employing a finite element package called COMSOL Multiphysics, and is also validated against some existing experimental observations. Finally, the model is used to simulate the mining-induced groundwater inrushes when the effect of faults and karst collapse columns is considered in the numerical simulation, and some suggestive conclusions for preventing water inrushes and optimizing underground mining operations are drawn.     

The Eastern Congo—a beauty spot,rediscovered from a geological point of view

In East Africa, the feedback between tectonic uplift, erosional denudation and associated possible climate changes is being studied by a multidisciplinary research group, ‘Riftlink’. The group's focus is the Albertine Rift, the northern part of the western branch of the East African Rift System, and in particular the rising Rwenzori Mountains that stretch along the border of the D.R. Congo and Uganda. Major questions relate to the timing of the formation of the Rwenzori Mountains, and whether the height of these mountains (> 5000 m) relates to rift movements in Neogene times, or represents an old basement block that formed a topographic high long before. Though, at first, research concentrated on the eastern (Ugandan) part of the Albertine Rift and Rwenzori Mountains, it has now moved further to the west to the D.R. Congo. A first field‐campaign, covering the area from northern Lake Edward along the rift shoulder up to the Blue Mountains at Lake Albert, was conducted in summer 2009, in cooperation with the Ruwenzori State University of Butembo. Here, we present a brief overview of the field‐campaign, with impressions gathered on the morphology and geology of the study area.     

The effect of the atmosphere on the propagation of high-power ultrabroadband microwave emission pulses

The effect of the atmosphere on the propagation of single successive pulses of the ultrabroadband microwave emission has been calculated in detail. It has been indicated that nonlinear effects mainly influence the propagation of the LF pulse part in the absence of divergence, which substantially affects the propagation of the following pulses.     

Chemical analysis of natural objects by ion chromatographic method in combination with a priori calculations using IONCHROM software

This paper briefly describes original developments in the theoretical and practical ion chromatography. It is demonstrated that new methods may be applied for the highly-selective analysis of complex natural objects. The determination of different species of sulfur and other ions in the condensates of fumarolic gases is considered in detail as an example.     

Separation of concentrated acid and salt solutions in nanoporous media as the basis for a new technology of processing of phosphorus-containing raw materials

The physical and mathematical models were used to study the method of acid retardation for separating acids from their salts in concentrated multicomponent solutions using nanoporous sorption materials. A combined mechanism of separation relies on the fact that in the sorption phase having a low dielectric permittivity, smaller-sized acid particles, namely, the molecules or strongly bound and weakly hydrated ion pairs, can penetrate the nanopores and are retained within these pores due to molecular sorption or competitive solvation forces. The dissolved salts presented by highly hydrated ions or weakly bound ion pairs can easily pass through the porous medium with a flow of concentrated solution, which is pumped through the column packed with the granulated bed of gel-type ion exchange resins or hypercrosslinked polymers. In conventional cyclic AR processes, purified acid is desorbed by water according to the mechanism of competitive solvation. However, such processes can be successfully used only when the salts separated from acids are highly soluble, as is the case with chloride and nitrate solutions free of components that may form compounds insoluble in neutral medium. At the separation in real sulfate and phosphate media, which normally contain alkaline earth metals and other components, conventional AR- based technologies proved to be unsuccessful. The new modified version of acid retardation is based on the previously discovered effect of stabilization of colloidal systems and supersaturated solutions in porous ion exchange media. A distinctive feature of the proposed technique is the use of weakly acidic aqueous solutions, instead of water, at the stages of acid displace in the cyclic AR processes. The proposed technique of WPA purification using strong-base gel-type ion exchangers in the phosphate form opens up the possibility of stable and feasible processes of acid separation and purification with simultaneous extraction of valuable components, e.g., REE concentrate.     

The subsidence and thermal history of the Baikit anteclise sedimentary basin

The Riphean rocks of the Baikit anteclise have been examined using pyrolysis Rock–Eval 6 to evaluate the subsidence history and erosion level. The studied Riphean rocks have the МK₃–МK₄ catagenesis grade. Based on the catagenesis of organic matter we propose a model of maximum burial before the beginning of the accumulation of Vendian deposits. Estimated calculations of subsidence and erosion have shown that the assessed catagenesis grade could be reached at a depth of 7 km, while the erosion level was approximately 5–7 km.     

The upper Bajocian of the Crimean Mountains: Paleogeography and sedimentation conditions from palynological data

Based on the spore-pollen data, the mineral composition of clay rocks, analyzed structures and facies, and a general paleogeographic analysis, the sedimentation conditions and landscapes of islands located during the Late Bajocian in the region of the present-day the Crimean Mountains have been reconstructed. It is shown that the sublatitudinally elongated insular land zone had a width of 30 km, the heights of the islands were no more than 1 km, with steep mudflow-affected northern slopes and with an extensive river system on the southern slopes.