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Journal articles on the topic 'Colmation layer'
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1
Dizer, H., G. Grützmacher, H. Bartel, H. B. Wiese, R. Szewzyk, and J. M. López-Pila. "Contribution of the colmation layer to the elimination of coliphages by slow sand filtration." Water Science and Technology 50, no. 2 (2004): 211–14. http://dx.doi.org/10.2166/wst.2004.0127.
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River bank or slow sand filtration is a major procedure for processing surface water to drinking water in central europe. In order to model the performance of river bank and slow sand filtration plants, we are studying the different mechanisms by which the elimination of pathogens is realized. An important question concerning the mode of action of slow sand filters and river bank filtration units is the role of the colmation layer or “schmutzdecke” on the elimination of human pathogens. The schmutzdecke is an organic layer which develops at the surface of the sand filter short after the onset of operation. We have inoculated a pilot plant for slow sand filtration with coliphages and determined their rate of breakthrough and their final elimination. In the first experiment, with a colmation layer still missing, the breakthrough of the coliphages in the 80 cm mighty sandy bed amounted to ca. 40%. In contrast, less than 1% of coliphages escaped from the filter as the same experiment was repeated two months later, when a substantial colmation layer had developed. Our preliminary conclusions are that the colmation layer is extremely efficient in eliminating of viruses.
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Karpf, Christian, Jens Traenckner, and Peter Krebs. "Hydraulic modelling of sewage exfiltration." Water Science and Technology 59, no. 8 (2009): 1559–65. http://dx.doi.org/10.2166/wst.2009.172.
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Exfiltration of waste water in sewer networks represents a potential danger for the soil and the aquifer. Various modelling approaches have been proposed to quantify sewerage exfiltration and its spatial and temporal variation. Common models are based on the law of Darcy, extended by a more or less detailed consideration of the expansion of leaks, the characteristics of the soil and the colmation layer. In the paper investigations are introduced, which are focused on the actual water content of the soil and its influence on exfiltration rates. Modelling results with HYDRUS 1D show, that under unsaturated conditions initial exfiltration rates are increased compared to saturated conditions. In experiments it was found, that the matrix potential increases the tightness of the colmation layer. Further a colmation model was deduced, which allows the calculation of the thickness and conductivity of the colmation layer.
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Ellis, J. B., D. M. Revitt, J. Vollertsen, and D. J. Blackwood. "Sewer exfiltration and the colmation layer." Water Science and Technology 59, no. 11 (2009): 2273–80. http://dx.doi.org/10.2166/wst.2009.271.
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Sewer rig studies demonstrate a rapid exponential decline in exfiltration rates from gaps and joints to establish an ultimate steady-state equilibrium varying between 10−3–10−6 l s−1, with minimum average daily rates per standardised leak area and sewer length varying between 0.02–9.0 l d−1cm−2 and 0.0002–2.0 l s−1 km−1 respectively. These loss rates are much larger than those derived from indirect monitoring/modelling studies which suggest losses between 1.4 × 10−5–0.179 l s−1 km−1. The confusion regarding conflicting definitions of the colmation, transition, bridging and biofilm layers is addressed, and the significance of these clogging layers in terms of both hydraulic and matrix potential on the exfiltration loss is evaluated. The influence of variability and instability of flow and bed turbulence on determining critical leakage conditions following the onset of equilibrium steady-state is assessed. This challenges the generally held assumption that elevated head pressure condition alone is a necessary precursor for rupture of the clogging layers.
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Brunke, Matthias. "Colmation and Depth Filtration within Streambeds: Retention of Particles in Hyporheic Interstices." International Review of Hydrobiology 84, no. 2 (1999): 99–117. http://dx.doi.org/10.1002/iroh.199900014.
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AbstractColmation refers to the retention processes that can lead to the clogging of the top layer of channel sediments and decolmation refers to the resuspension of deposited fine particles. Internal colmation, clogging of the interstices directly below the armor layer, may form a thin seal that disconnects surface water from hyporheic water by inhibiting exchange processes. The settling of particles under low flow conditions can cause external colmation. Colmated channel sediments are characterized by reduced porosity and hydraulic conductivity as well as by a consolidated texture. The term ‘depth filtration’ refers to the transport and storage of fine matrix sediments in interstitial layers. Depth filtration is of significance for the transport of colloidal and fine particulate inorganic as well as organic matter within the hyporheic interstices and into the alluvial aquifer. The role of depth filtration is assessed for the content (given in mg per liter) of matrix fine particles retained in the coarse framework sediment of a gravel‐bed river in Switzerland. Sediment samples were taken by freeze‐coring with liquid nitrogen down to 70 cm depth and by piezometers down to 150 cm depth. Seventy‐two percent of the mobile matrix fine particles were smaller than 0.1 mm and 50% were smaller than 0.03 mm. The content of fines tended to increase with depth, although higher accumulations were found at intermediate depths in sediments influenced by exfiltrating ground water. Interstitial detrital particles >90 μm showed vertical distribution patterns opposing those of total particles. These relationships revealed a differential significance of import, storage, and transport within three types of hydrological exchange zones (infiltration, horizontal advection, exfiltration) in the cross‐section of the stream.
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Karpf, Christian, and Peter Krebs. "A new sewage exfiltration model – parameters and calibration." Water Science and Technology 63, no. 10 (2011): 2294–99. http://dx.doi.org/10.2166/wst.2011.167.
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Exfiltration of waste water from sewer systems represents a potential danger for the soil and the aquifer. Common models, which are used to describe the exfiltration process, are based on the law of Darcy, extended by a more or less detailed consideration of the expansion of leaks, the characteristics of the soil and the colmation layer. But, due to the complexity of the exfiltration process, the calibration of these models includes a significant uncertainty. In this paper, a new exfiltration approach is introduced, which implements the dynamics of the clogging process and the structural conditions near sewer leaks. The calibration is realised according to experimental studies and analysis of groundwater infiltration to sewers. Furthermore, exfiltration rates and the sensitivity of the approach are estimated and evaluated, respectively, by Monte-Carlo simulations.
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Harvey, Ronald W., David W. Metge, Denis R. LeBlanc, et al. "Importance of the Colmation Layer in the Transport and Removal of Cyanobacteria, Viruses, and Dissolved Organic Carbon during Natural Lake-Bank Filtration." Journal of Environmental Quality 44, no. 5 (2015): 1413–23. http://dx.doi.org/10.2134/jeq2015.03.0151.
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Rakhimbayev, Shark M., Natalia M. Tolypina, Elena N. Khakhaleva, and Daniil A. Tolypin. "Comparative Resistance of Concrete with Aggregates and Fillers of Different Composition." Materials Science Forum 1017 (January 2021): 133–42. http://dx.doi.org/10.4028/www.scientific.net/msf.1017.133.
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The paper studies the influence of aggregates and fillers with negative and positive electrical surface properties on the corrosion resistance of concrete. The advantage of resistance of fine-grained concrete on marble sand in comparison with concrete on quartz sand, regardless of the type of aggressive environment, is established. At the same time, the stability of samples of powdered concrete with 10 and 30% of fine-grained filler changed little when replacing the quartz powder with marble one. It is shown that the resistance coefficients of powdered concrete samples with quartz filler (10%) do not differ from the resistance coefficients of samples of a similar composition with crushed marble filler, and with an increase in the dosage of the filler (30 %) slightly exceed. It was found that in powder concretes without aggregates, the contact layer between the cement matrix and the aggregate is absent, so the composition of the mineral powder plays a much smaller role in the corrosion processes of cement stone. The obtained results allowed establishing that electrokinetic phenomena play a secondary role, and the main influence on the stability of fine-grained concrete is the processes of pore colmation by chemical reactions, as well as the interaction of the surface layers of the aggregate with the cement matrix.
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Rakhimbayev, Shark M., Natalia M. Tolypina, Elena N. Khakhaleva, and Daniil A. Tolypin. "Comparative Resistance of Concrete with Aggregates and Fillers of Different Composition." Materials Science Forum 1017 (January 2021): 133–42. http://dx.doi.org/10.4028/www.scientific.net/msf.1017.133.
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The paper studies the influence of aggregates and fillers with negative and positive electrical surface properties on the corrosion resistance of concrete. The advantage of resistance of fine-grained concrete on marble sand in comparison with concrete on quartz sand, regardless of the type of aggressive environment, is established. At the same time, the stability of samples of powdered concrete with 10 and 30% of fine-grained filler changed little when replacing the quartz powder with marble one. It is shown that the resistance coefficients of powdered concrete samples with quartz filler (10%) do not differ from the resistance coefficients of samples of a similar composition with crushed marble filler, and with an increase in the dosage of the filler (30 %) slightly exceed. It was found that in powder concretes without aggregates, the contact layer between the cement matrix and the aggregate is absent, so the composition of the mineral powder plays a much smaller role in the corrosion processes of cement stone. The obtained results allowed establishing that electrokinetic phenomena play a secondary role, and the main influence on the stability of fine-grained concrete is the processes of pore colmation by chemical reactions, as well as the interaction of the surface layers of the aggregate with the cement matrix.
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Gunkel, G., C. Beulker, B. Grupe, and F. Viteri. "Survey and assessment of post volcanic activities of a young caldera lake, Lake Cuicocha, Ecuador." Natural Hazards and Earth System Sciences 9, no. 3 (2009): 699–712. http://dx.doi.org/10.5194/nhess-9-699-2009.
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Abstract. Cuicocha is a young volcano adjacent to the inactive Pleistocene Cotacachi volcano complex, located in the western cordilleras of the Ecuadorian Andes. A series of eruptions with intensive ash emission and collapse of the caldera occurred around 4500–3000 y BP. A crater 3.2 km in diameter and a maximum depth of 450 m was formed. Further eruptions of the volcano occurred 1300 y BP and formed four smaller domes within the caldera. Over the last few hundred years, a caldera lake has developed, with a maximum depth of 148 m. The lake water is characterized by sodium carbonate with elevated concentrations of manganese, calcium and chloride. Nowadays, an emission of gases, mainly CO2, and an input of warm spring water occur in Lake Cuicocha. The zone of high activity is in the western basin of the lake at a depth of 78 m, and continuous gas emissions with sediment resuspension were observed using sonar. In the hypolimnion of the lake, CO2 accumulation occurs up to 0.2% saturation, but the risk of a limnic eruption can be excluded at present. The lake possesses monomictic stratification behaviour, and during overturn an intensive gas exchange with the atmosphere occurs. Investigations concerning the sedimentation processes of the lake suggest only a thin sediment layer of up to 10–20 cm in the deeper lake basin; in the western bay, in the area of gas emissions, the lake bottom is partly depleted of sediment in the form of holes, and no lake colmation exists. Decreases in the lake water level of about 30 cm y−1 indicate a percolation of water into fractures and fissures of the volcano, triggered by a nearby earthquake in 1987.
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Borovyk, М. V., А. P. Vovk, and М. V. Gordijchuk. "Colmatating of productive gas formations while drilling wells with abnormally lower hydrostatic pressures." Prospecting and Development of Oil and Gas Fields, no. 4(81) (December 28, 2021): 16–23. http://dx.doi.org/10.31471/1993-9973-2021-4(81)-16-23.
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Today the pressures in productive gas collectors on the Dnieper-Donets rift are considerably lower than hydrostatic ones. Opening such formations while drilling is a challenging task in terms of preventing losses and differential pressures. In order to solve the problem, one needs to improve the methods of effective temporary colmation of productive formations with acid-soluble materials under the conditions of abnormally low formation pressures during drilling on fields with late terms of development. Traditional algorithms of lost circulation control in abnormally low reservoir pressure, developed by leading world services companies, often turn out to be unworkable. In order to conduct the lost circulation control, one often chooses colmatants, which totally align with the principles of ideal packaging, however do not meet the criterion of strength or resistance to significant differential pressure. As a result, in the course of the subsequent drilling there can be another circulation loss in already colmated layer. In Ukraine the lost circulation control sphere is being developed by means of selecting colmatants according to a new principle. The article has proposed the activities for the lost circulation curing and pollution reducing of productive collectors. For this purpose the generalized characteristic-criterion of colmatants has been developed and used. The criterion got a name “flexibility”, i.e. a deformation, compaction and penetration (into porous-fissured medium) capability under immense pressure. With the help of the criterion the set of particular colmatant have been chosen; also, principles of colmatant mixtures selection under the relevant geological and mining conditions have been identified. In many cases, there is no need to calculate the physical parameters of the formation and the circulation loss crack due to flexibility of colmatant; one only has to select the optimal concentrations of materials and the periodicity of input these materials to the mud. The developed technology confirms the need to improve the algorithms for circulation loss prevention and curing, primarily for conditions of abnormally low reservoir pressures.
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Karimova, L. M., and Y. T. Kairalapov. "Percolation leaching of clay mixed copper ores." iPolytech Journal 26, no. 1 (2022): 142–53. http://dx.doi.org/10.21285/1814-3520-2022-1-142-153.
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The present work addresses the problem of improving the percolation properties of heap leaching piles of clay, slime-oxidised and mixed ores. These ores are prone to colmatation, which hinders percolation of the solution through the ore layer. Laboratory tests on percolation leaching were carried out using a 2 m column having an internal diameter of 190 mm, loaded with 89.42 kg of ore material having a grain size of -55+0 mm. In order to eliminate colmatation, the ore layer was divided into two equal parts by a drainage layer of polystyrene foam. The research object was ore material extracted from the northern Nurkazgan deposit (Karaganda region, Republic of Kazakhstan), in which copper is present in the form of sulphide (53.48%) and oxidised minerals (46.52%), including 23.5% of chrysocolla. The mineral composition of a test sample determined by optical and electron microscopy, X-ray diffraction, local X-ray spectral, X-ray fluorescence and inductively coupled plasma mass spectrometry was characterised by 93.78% of rock-forming minerals, 53.23% of which comprised layered silicates, namely, mica, chlorite and kaolinite. Ore mineralisation was characterised by both sulphide (copper sulphides, pyrite) and oxide (malachite, iron hydroxides and manganese oxides) phases. The content of easy-sliming minerals equalled 56.30%. Prior to leaching, moisture saturation during the period of one day was carried out. The ore was top irrigated with a solution of sulphuric acid having a concentration of 60 g/dm3. Pregnant solutions were processed following a sorption method (sorption/desorption–electrolysis). The copper extraction into the solution yielded 60.04% with a sulphuric acid consumption of 50.0 kg/t ore at an average irrigation rate of 10.58 dm3/(m2h) or 0.1058 dm/h per clear opening. Therefore, heap leaching of ores at a layer height of lower than 1 m can be performed following the "leaching–extraction/re-extraction or sorption/desorption–electrolysis" scheme.
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Absametov, M. K., E. Zh Murtazin, V. V. Kulagin, A. T. Makyzhanova, and A. Zh Ismagulova. "INFILTRATION AND COLMATATION DYNAMICS ON PHYSICAL MODELS STUDY BY INFILTRATION BASINS AT ARTIFICIAL GROUNDWATER RECHARGE." Water Conservation & Management 7, no. 1 (2023): 45–54. http://dx.doi.org/10.26480/wcm.01.2023.45.54.
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The problem of the growing shortage of water resources in the world, including in the territory of South-East Kazakhstan, due to global warming and aggravated by long distances to natural sources of good quality water, requires the combined use of surface water and groundwater from local aquifers to supply the local population with high-quality drinking water. The application of methods of artificial groundwater spreading can be an effective way only if positive characteristics of soil and soil parameters of the aeration zone and productive aquifers are obtained in the processes of infiltration and colmatation, which are one of the decisive indicators for ensuring productivity and duration of operation of infiltration basins in the given mode. This work presents the main results of complex field studies of the processes of infiltration and colmatation in infiltration mini-basins at pilot sites within the Aksu, Lepsy and Koksu river valleys, taken as typical for the territory of South-Eastern Kazakhstan, which most needs to increase the water supply of rural population settlements and remote pastures. These studies were supplemented by a detailed assessment of the water-physical, hydrodynamic and filtration properties of the overburden and the upper layers of the aquifer. The new data showed that the infiltration rate varied from 15 m/day at the beginning to 0.75 m/day at the end and remained practically unchanged by the end of the experiment. This was largely facilitated by the values of the heterogeneity coefficient of the granulometric composition of all the examined soils obtained during the studies, which did not exceed 3.0 due to the uniform distribution of coarse fractions and a small proportion of loams and sandy loams. Approximately one month after the start of the tests, a colmatation layer began to be generated at the bottom of the mini-ponds, the thickness of which by the end of the test reached from 3 mm for clay silt to 6 mm for silty clay. However, as studies have shown, the generation of a colmatation layer due to the settling of suspended particles of surface water did not significantly impact on the infiltration processes, as evidenced by the rated values of specific flow rates, which in the final period of time ranged from 0.86 to 0.75-0.80 m3/day per square meter of reduced infiltration surface. Thus, the generated positive results of field studies can serve as a factual basis for design, and can also be recommended and accepted as design indicators both at the stage of a feasibility study and at the stage of detailed design of artificial groundwater spreading systems without additional labor-intensive and costly survey works, and the approved methodology for their implementation will be useful when conducting similar studies in other regions.
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Almukhametova, Elvira. "A comparison of current development system indicators for the oil-bearing layers under the abandonment of non-stationary water-flooding and hot water injection technologies." E3S Web of Conferences 480 (2024): 01017. http://dx.doi.org/10.1051/e3sconf/202448001017.
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In this work, based on the calculation of technological indicators, an assessment of the effectiveness of the development of a field with high-viscosity oil is made. It has been established that when hot water is injected, displacement occurs unevenly, which affects the performance of wells. When analyzing the further stage of development, which consisted in the use of thermal effects, the following was revealed: in order to successfully increase the oil recovery coefficient, it is necessary to create high pressure gradients in order to prevent dagger flooding of wells and (or) colmatation of the bottomhole formation zone, including perforations. With the help of calculations, the effectiveness of thermal exposure and stationary flooding was compared, as a result of which conclusions were obtained that allow us to give a number of practical recommendations aimed at improving the processes of oil displacement by a working agent.
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Wilk, Krzysztof. "Hazards for buildings and structures caused by flood conditions." E3S Web of Conferences 45 (2018): 00101. http://dx.doi.org/10.1051/e3sconf/20184500101.
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Floods are one of the common natural phenomena that can cause a huge danger to people and building objects located in flood plains. The particularly severe effects of such disasters are felt in heavily urbanized areas [1, 2]. The development of river valleys causes difficulties in the flow of flood water and the protective embankments limit the possibility of the temporary accumulation of water. The consequence of this situation is increasing the level of the flood wave and thereby intensifying its negative impact. Damages to the building during inundations can be the result of not only the direct activity of the flood wave and surface water, but also changes in groundwater flow conditions, including the increase of their piezometric level [3, 4]. An increasing of groundwater pressure can intensify or initiate new phenomena related to permeability (suffosion, colmatation, etc.) and consequently conduce disadvantageous changes of soil substrate parameters [5]. The influence of such processes can be revealed later, after the floods stage recede. The local conditions of water flow and the ground structure have a direct impact on the probability of occurrence of specific phenomena threatening construction objects (initiated by floods).
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Strokin, K. B., A. A. Galtsev, V. S. Konovalova, and B. E. Narmaniya. "The effect of calcium stearate on the microbiological corrosion of cement stone concrete." Stroitel nye Materialy, no. 8 (September 7, 2024): 25–29. http://dx.doi.org/10.31659/0585-430x-2024-827-8-25-29.
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To prevent biofouling of cement stone and its damage by fungal microorganisms, it is proposed to introduce 0,5 wt. % calcium stearate into the cement mixture. To ensure volumetric hydrophobization of cement stone, the additive is crushed to nanoparticles. The cement stone was cured in the air for 28 days. To study fungal corrosion, the surface of the cement stone was treated with a suspension of pores of Aspergillus niger fungi. The hydrophobic surface of the cement stone was not biofouled by fungal microorganisms Aspergillus niger during 6 months of the samples being in a humid environment, and black mold foci developed on the surface of ordinary cement stone during this period of time. The action of fungi and their waste products caused a decrease in the amount of calcium in the cement stone by 9 %, and had no effect on the hydrophobized cement stone. Due to the immunity of cement stone with a hydrophobizer to the action of microorganisms and water, free calcium hydroxide is not removed from the structure, but some amount is washed out of the surface layer and the pore liquid. A significant slowdown in mass transfer in cement stone under the action of liquids is provided by the hydrophobicity of the surface of cement stone and the walls of pores and capillaries, imparted by calcium stearate, as well as partial colmatation of the pore structure by means of the introduced additive.
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Yadav, Prabhas Kumar, and Mudassar Tufail. "River Bank Filtration Simulator (RBFSim)." April 25, 2022. https://doi.org/10.5281/zenodo.6482752.
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ГАЛЧЕНКО, Ю. П. "SCIENTIFIC SUPPORT OF THE TECHNOLOGY OF USING THE DEVELOPED SPACE OF THE CHAMBERS FOR THE PLACEMENT OF SOLID WASTE OF VARIOUS DISPERSITIES." Инженерная физика, no. 8 (August 31, 2021). http://dx.doi.org/10.25791/infizik.8.2021.1223.
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Одним из перспективных направлений развития геотехнологии подземного освоения недр является решение проблемы замкнутого цикла обращения твёрдого вещества, посредством использования выработанного пространства для складирования отходов обогатительного передела. Одним из наиболее дешёвых путей решения этих вопросов является использование в качестве фильтрующих и ограждающих систем отбитой горной массы, остающейся на днищах камер после выпуска из них руды. Для изучения этих процессов были построены две модели камеры в масштабе 1:25 и 1:50 и подготовлена методика исследований. Фазовый состав пульпы, применяемой при моделировании на первом его этапе, был принят Т:Ж=70:30, что соответствует фазовому составу пульпы после первой ступени гидроциклонирования. Процесс кольматации хорошо прослеживается по соотношению объёмов на первых двух этапах эксперимента. Слой твёрдого, оставшийся после первой заливки (4,7 кг), потерял устойчивость во время подачи второй порции и был перемещён вместе с частью её твёрдой фракции в пустоты между кусками дробленого материала. Этот процесс имел ярко выраженный двух стадийный характер. Сначала часть твёрдого материала пульпы аккумулируется на поверхности дробленого материала, а затем – переносится в его пустоты вместе с твёрдой компонентой второй порции пульпы. Кольматированная рудная масса обладает хорошими фильтрационными свойствами и высоким гидравлическим сопротивлением, достаточным для постановки в перспективе исследований по обоснованию технологии закладки камер хвостами обогащения с сохранением подготовительных выработок, возможно необходимых в будущем при частичной отработке междукамерных целиков. One of the promising directions of the development of geotechnology for underground mining is the solution of the problem of a closed cycle of solid matter circulation, through the use of the developed space for storing waste of processing processing. One of the cheapest ways to solve these problems is to use the broken rock mass remaining on the bottoms of the chambers after the ore is released from them as filtering and enclosing systems. To study these processes, two models of the camera were built at a scale of 1: 25 and 1:50 and a research methodology was prepared. The phase composition of the pulp used in the simulation at its first stage was assumed to be T:W=70: 30, which corresponds to the phase composition of the pulp after the first stage of hydrocycloning. The process of colmatation is well traced by the volume ratio at the first two stages of the experiment. The solid layer remaining after the first filling (4.7 kg) lost its stability during the second serving and was moved along with part of its solid fraction into the voids between the pieces of crushed material. This process had a pronounced two-stage character. First, a part of the solid pulp material accumulates on the surface of the crushed material, and then it is transferred to its voids together with the solid component of the second portion of the pulp. The colmated ore mass has good filtration properties and high hydraulic resistance, which is sufficient for setting up studies in the future to justify the technology of laying chambers with tailings of enrichment while preserving the preparatory workings, which may be necessary in the future for partial development of inter-chamber pillars.