Thick Alluvium Research Articles

Study on the “Two-Zone” Heights in Lower Slice Mining Under Thick Alluvium and Thin Bedrock

The extraction of thin bedrock coal seams with thick alluvium poses a challenging issue in the realm of coal safety production in China. Especially for mining under aquifers, knowing the development height of water-conducting fracture zones above the goaf is crucial for coal mine safety and production. Taking the 11092 working face of lower slice mining in Zhaogu No. 1 Mine as an example, the failure transfer process of the overlying strata is analyzed first. On this basis, the development height of the water-conducting fracture zone is predicted using empirical formulas and the BP neural network. According to the empirical formula, the height of the roof caving zone ranges from 6.93 m to 27.72 m, while the height of the water-conducting fracture zone ranges from 22.17 m to 71.73 m. The BP neural network predicts that the development height of the water-conducting fracture zone in the working face after mining is 56.83 m. CDEM numerical simulation is employed to analyze the development height of two zones of overburden rock. The findings indicate that with a mining height of 2.5 m and a cumulative mining height of 6 m, the maximum caving ratio is 2.61. It is observed that for a cumulative mining thickness of less than 6 m, a bedrock thickness of not less than 30 m, and a clay layer thickness exceeding 5 m, the clay layer effectively obstructs the upward development of the water-conducting fracture zone. Finally, the prediction results of the development height of the two zones of overlying strata in the working face are verified by using the height observation method on the underground water-conducting fracture zone and the borehole peeping method. In conclusion, the height of the overlying strata after mining the lower slice working face in the first panel of the east can be used as a basis for determining the thickness of coal (rock) pillars for waterproofing and sand control safety during the mining of lower slice working faces in mines.

From the Northern Hajar Foothills to the Batinah Coast – a Geoarchaeological Survey at Saham and Dahwa (Northern Oman)

This geoarchaeological survey was dedicated to (i) the Umm an-Nar (2700–2000 BCE) settlement site of Dahwa and surrounding areas in the foothills of the Hajar Mountains as well as (ii) the coastal area near Saham on the Batinah coastal plain in northern Oman, the latter without focus on a specific cultural epoch. Stratigraphic sections from the proximal coastal plain provide insights into highly dynamic episodic sedimentation patterns with thick units of variable grain sizes and sorting. In one of the stratigraphic profiles in the town of Saham, a small anthropogenic pit or channel was found, interpreted as a pit hearth used by the Samad culture (300 BCE–100/200 CE) based on granulometry, thin-section analysis, clustered macro-charcoals, amorphous organic remains, as well as luminescence and 14C dating. Our coincidental discovery of this site indicates that there might be abundant traces of the Samad culture buried in the thick alluvium, from a period of hydrologically favourable conditions c. 50–300 CE. The Umm an-Nar dating of the Dahwa archaeological site in the foothills of the Hajar Mountains was confirmed for the first time by luminescence dating, although the low dose rate and high scatter of equivalent doses pose substantial challenges to the regional application of this method.

Estimating catchment‐scale sediment storage in a large River Basin, Colorado River, USA

Estimating <scp>catchment‐scale</scp> sediment storage in a large River Basin, Colorado River, <scp>USA</scp>

Research on the Mechanical Characteristics of Thick Alluvium on the Surface Subsidence Features of Thin Bedrock Deposits at Depth

Research on the Mechanical Characteristics of Thick Alluvium on the Surface Subsidence Features of Thin Bedrock Deposits at Depth

Simulation and On-Site Detection of the Failure Characteristics of Overlying Strata under the Mining Disturbance of Coal Seams with Thin Bedrock and Thick Alluvium.

When mining deep coal seams with thin bedrock and thick alluvium, the collapse and fracture of thin bedrock layers may cause geological disasters, such as water inrush and sand inrush of the mining face. Comprehensively obtaining the response data of coal mining and reasonably analyzing the failure characteristics of overlying strata are helpful in guiding safe production. In this study, the caving zone heights of overlying strata are obtained by field detection during layered mining. Then, the caving zone heights during the once-full-height mining are evaluated by theoretical analysis. Further, the force and failure characteristics of coal-rock structures under different mining conditions are compared by the simulation detection and analysis. Finally, the results of on-site observation, theoretical analysis, and simulation detection are compared and discussed, and an optimized mining technology is proposed to ensure safe mining. The research shows the caving zone heights of on-site and simulation detections are, respectively, 14.65 m and 13.5 m during bottom-layer mining, which is larger than the caving zone heights of the top-layer coal mining. During once-full-height mining, the maximum caving zone height of simulation detection is 21 m, which is in between two standard results. For the mechanical responses of an aquiclude clay layer under thick loose alluvium, the maximum disturbance displacement of clay aquiclude is 5.8 m during layered mining, which is slightly larger than the disturbance displacement of once full-height mining; however, the maximum stress of the clay layer is 25 MPa during once-full-height mining, which is larger than the maximum stress of clay layer during layered mining. For the clay aquiclude failure, the clay layer during layered mining is in the deflection deformation area, and there is no obvious fracture structure to inrush the water and sand of thick loose alluvium; however, the clay layer during once-full-height mining is prone to produce obvious fracture structure. Therefore, the layered mining technology can effectively reduce and prevent the water/sand inrush disaster of mining working face.

Field monitoring of alluvium accumulation in the riverine floodplain of the Oka River, European Russia

Sedimentation traps were used to assess the annual surface renewal dynamics of the low floodplain of the Oka River (a major tributary of the Volga River in central European Russia). Trap-mats and platforms made of crushed bricks were installed in positions near the meandering and relatively straight riverbed, in different sedimentation environments. Stationary research in 2014–2020 covered a section of the bottom of the Oka River valley with a length of more than 400 km along the main channel. The graphical-analytical processing of field data using Ferret's Triangles and sedimentation diagrams showed that transport and deposition of suspended sediment dominated in the accumulation of 87% of alluvium samples. The formation of ripples was not recorded, which was lithologically reflected in the horizontal layering of the new sediment. The determination of the granulometric composition of the removed sediment and their thickness on the traps showed the absence of statistically significant differences according to the Kruskal–Wallis test between the data samples from the trap-mats and trap-platforms. The reference to the daily calendar of synoptic mechanisms according to the classification of Dzerdzeevsky contributed to the identification of meteorological prerequisites for the variation of the hydrograph curve of the Oka River in its middle reaches. Prolonged floods caused by the premature arrival of spring lead to massive deposition of silt and clay particles even on sandbanks. On the other hand, short (15–35 d) March floods and abnormal high water in June, caused by Atlantic cyclone intrusions, can stabilize sand accumulation on the riverine floodplain. The thickest sediment layers on the traps were obtained in 2018 after a very cold March and a powerful April flood, and the overall distribution of alluvium thickness and its particle size distribution also depends on the morphology of the riverine relief. The siltation is caused by the accumulation of silts; the most finely dispersed sediment was deposited in those facies environments for which siltation was also characteristic in historical times.

Experimental study of ground improvement techniques of soft Kaolin soil using sand drain and jute wrapped with polyamide polyester vertical drain”

Thick alluvial deposits of soft clayey soils are characterized by low shear strength, high compressibility and low hydraulic conductivity. In recent years, soil improvement is required to provide adequate bearing capacity and improve shear strength of the soft cohesive soils to satisfy the need for various type of construction on sites underlain by such soft soils. Amongst various ground improvement techniques like vibroflotation, compaction with explosive, electro-osmosis, heavy tamping, stone column etc., the technique of preloading or pre-compression used in combination with vertical drains is one of the oldest and most widely used techniques to preconsolidate and strengthen weak compressible soils in situ. To accelerate the time of Primary consolidation, Prefabricated Vertical drains are used in soft clays as they decrease the drainage path. In this paper, we investigate the consolidation rate of soft soil with Sand drain and jute wrapped with polyamide polyester drain as PVD. The present paper focuses on Study of pore water dissipation, effect on consolidation due to radial drainage flow and gain in strength using 254 mm diameter Rowe Type Oedometer for both the drain materials. The load in increment of ΔP/P = 1 is applied and measurement of settlement by conventional method is done. It is observed that Jute wrapped with polyamide polyester drain as PVD performs better in comparison to Sand Drain.

Patterns of Alluviation in Mixed Bedrock‐Alluvial Channels: 2. Controls on the Formation of Alluvial Patches

AbstractUnderstanding the development and spatial distribution of alluvial patches in mixed bedrock‐alluvial rivers is necessary to predict the mechanisms of the interactions between sediment transport, alluvial cover, and bedrock erosion. This study aims to analyze bedrock alluviation patterns using a 2D morphodynamic model, and to use the model results to better understand the mechanisms responsible for alluvial patterns observed experimentally. A series of simulations are conducted to explore how alluvial patterns in mixed bedrock‐alluvial channels form and evolve for different channel slopes and antecedent sediment layer thicknesses. In initially bare bedrock low‐slope channels, sediment cover increases with increasing sediment supply because areas of Froude‐subcritical flow enable sediment deposition, while in steep‐slope channels the flow remains fully supercritical and the model predicts so‐called runaway alluviation. For channels initially covered with sediment, the model predicts a slope‐dependent sediment supply threshold above which sediment cover increases with increasing sediment supply, and below which the bedrock becomes fully exposed. For a given sediment supply, the fraction of bedrock exposure and average alluvial thickness converge toward the equilibrium value regardless of the initial cover thickness as long as it exceeds a minimum threshold. Steep channels are able to maintain a continuous strip of sediment under sub‐capacity sediment supply conditions by achieving a balance between increased form drag as bedforms develop and reduced surface roughness as the portion of alluvial cover decreases. In lower‐slope channels, alluvial patches are distributed sporadically in regions of the subcritical flow.

Electrical Resistivity - Tomography Studies In Determining Shallow Aquifer Potential Zones a Case Study in Different Terrains

The study documents the effectiveness of 2 D (Two Dimensional Electrical Resistivity Survey (Tomography) to map shallow subsurface geological formations namely recent Alluvium, Gondwana deposits and hard rock deposits. 2 dimensional Electrical Resistivity Survey (or tomography) was conducted at 2 locations at Valarpuram and one location Madurantakam areas. Gondwana deposits mask Valarpuram Thandalam, villages (at Kancheepuram District, Tamilnadu). To the east of Valarpuram alluvium thickness increases at shallow depths. Weathered and hard granitic gneiss and hard charnockite rocks overlie topsoil in Madurantakam areas (Chengalpettu District, Tamilandu). The survey was conducted to 12 m depth to decipher shallow permeable zones. Gondwana formations consisting of clays, siltstones are predominant in Valarpuram Thandalam and surrounding areas. Hard rock formations are found in Madurantakam areas. 2 Dimensional Resistivity Survey results indicate 2-D sections with very low resistivity values in the range of 2 to 4 ohm-m in Valarpuram Thandalam areas indicating predominant clay deposits with poor ground water potential. To the east of Valarpuram Thandalam resistivity data is of moderately higher value indicating sand deposits at shallow depths. These are ideal locations for dug wells. Low to moderate values at shallow depths indicating weathered thickness up to 12 m are observed at Madurantakam location. From 12m depth steep rise in resistivity values are observed in hard indicating presence of massive rock from 12m depth and below areas. Thus, 2 D Resistivity Imaging Technique are helpful in delineating shallow aquifer potential and this in turn helps in deciding the depth of open wells with high precision.

Alluvial deposit model in alluvial formation in East Belitung Regency

Belitung Island is known to have natural resources similar to Bangka Island, where there are many mineral contents in it. Especially in alluvial deposits, minerals are found due to weathering processes that contain minerals in economical amounts, generally these minerals are kaolin and quartz. This research was conducted in geological investigations carried out by field mapping, pit sampling, geoelectric tests, and geochemical tests. Based on the result of geoelectric test, it can be known that the potential of minerals deposits in alluvial found at depths from 0,5 to >10 meters with thickness of alluvial deposits up to 18 meters. The results of the observation pit sampling found that the economical mineral layer was in the form of quartz sand deposits with a thickness of up to 7 meters and kaolin deposits with a thickness of 0.5 meters. The results of geochemical tests of pit sampling samples show the percentage of quartz is 99,6% and others 0,4 %.

Geophysical Constraints to Reconstructing the Geometry of a Shallow Groundwater Body in Caronia (Sicily)

The characterization of a groundwater body involves the construction of a conceptual model that constitutes the base knowledge for monitoring programs, hydrogeological risk assessment, and correct management of water resources. In particular, a detailed geological and geophysical approach was applied to define the alluvial Caronia Groundwater Body (CGWB) and to reconstruct a hydrogeological flow model. The analysis of the CGWB, located in north-eastern Sicily, was initially approached through a reanalysis of previous stratigraphic (boreholes) and geophysical (vertical electrical soundings and seismic refraction profiles) data, subsequently integrated by new seismic acquisitions, such as Multichannel Analysis of Surface Waves (MASW) and horizontal-to-vertical seismic ratio (HVSR). The analysis and reinterpretation of geoelectrical data allowed the construction of a preliminary 3D resistivity model. This initial modeling was subsequently integrated by a geophysical data campaign in order to define the depth of the bottom of the shallow CGWB and the thickness of alluvial deposits. Finally, a preliminary mathematical model flow was generated in order to reconstruct the dynamics of underground water. The results show that integration of multidisciplinary data represent an indispensable tool for the characterization of complex physical systems.

Devonian diamond reservoir of the Urals

Research subject. The Takata formation of the Emsian tier of the Lower Devonian (D1tk) in the Urals is a reservoir of Devonian diamonds. Aim. Confirmation and determination of the diamond-bearing conditions of the reservoir. Materials and Methods. Generalization of primary and interpreted geological information. Lithofacial analysis. Historical and geological reconstruction. Cartographic analysis and geological and cartographic modeling in the ArcMapESRY GIS environment using the ModelBuilder module. Results. The Takata formation is part of the Emsian tier of the Lower Devonian. Tectonically, the Takata formation is located in the West Ural Folded Zone. The diamond content in the Urals is spatially related to the outputs of the Takata formation. The industrial diamond-bearing capacity and the highest density of diamond placers are located in the Vishersky, Chykmansky and Chusovskoy diamond-bearing regions of the Northern and Middle Urals within the Perm Krai. In the early Devonian, the Takata Sea existed in the Vishera diamond-bearing area; a large river with a delta flowed in the direction from northwest to southeast. The sediments of the formation comprise the facies cycle: flood-plain - channel alluvium - delta sediments - underwater-delta - marine sediments. Diamonds are concentrated in the thickness of coarse-grained alluvium, small-pebble basal conglomerates that formed on the land-sea boundary of the paleocontinent of the Russian Plate. Three facies types of the Takata formation section are distinguished: continental, coastal-marine and marine. Its diamond-bearing capacity is associated with the continental and coastal-marine sediments of the formation within the Perm Region. To the north and south of the diamond-bearing areas of the Perm Krai, the Takata formation is represented by marine sediments. According to the geodynamic model based on the geological section of the Northern Urals, the alluvial and coastal-marine Takata diamond placers were formed in the early Devonian as a result of the demolition of material from the Russian Plate. The sources of destruction were rocks of the Precambrian, Ordovician and Silurian. The main spatial-geomorphological criterion for searching for diamond-bearing conglomerates of the Takata formation is the maximum distance of demolition from these conglomerations to placers, equal to 500 m.

Evaluation of management scenarios for land subsidence reduction and groundwater rehabilitation in Damane-Daran plain, Iran

Land subsidence by excessive groundwater extraction is one of the most important issues that many countries face. In the recent two decades, Damane-Daran aquifer in Iran faces severe land subsidence, caused by excessive groundwater extraction. This study investigates and presents management scenarios to rehabilitate and balance the aquifer. In this regard, a 3D model of groundwater and a 1D model of land subsidence is developed. Our designed scenarios include I) continuing the current trend in water extraction, II) reducing water extraction by 25%, III) reducing water extraction by 50%, IV) reducing water extraction by 75%, and V) increasing recharge in critical subsidence area by 200%. Our results show that the land subsidence trend follows groundwater level changes. This relationship is however non-linear and apart from the groundwater level, it depends on different parameters such as alluvium thickness, storage coefficient, etc. We show that continuing the current water extraction can cause maximum subsidence of 0.65 m in the aquifer. Through the employment of scenarios II to IV, this amount reaches 0.52 m, 0.41 m, and 0.31 m, respectively. Scenario V is the only successful scenario in aquifer quantity rehabilitation, but it does not affect the land subsidence balance. To prioritize the scenarios, scenario IV is the most favorable scenario, followed by scenario III, scenario II, and scenario V. Furthermore, results show that those parts of the aquifer with the highest subsidence rate are mostly associated with the agricultural fields in the eastern and central parts of the aquifer.

Study of the Catastrophic Process of Water–Sand Inrush in a Deep Buried Stope with Thin Bedrock

Taking the 14,030 panel of Zhaogu No. 2 coal mine as its research object, this paper studies the evolution characteristics of the developing height, propagation track and caving arch shape of water-flowing fractures under the influence of thick alluvium by utilizing a physical experiment, theoretical analysis and field investigation. The results show that the height and limit span of the water-flowing fracture zone experience four stages, which include the initial stage, slow-increasing stage, sudden-increasing stage and stable-increasing stage. With the increase in the mining influence range, the shape of the water-flowing fracture in overburden under the influence of thick alluvium is gradually formed. The water in the thick alluvium and the water in the upper phreatic aquifer of the bedrock penetrate each other to form a concentrated danger zone, and the expansion track of the mining water-flowing fracture connects the hydraulic connection between the upper concentrated danger zone of overburden and the panel of No. 2’s first coal seam. A large amount of water mixed with sandstone flows into the fracture surface of the bedrock’s broken rock block through the water-flowing fracture, leading to the instability of the load-bearing structure composed of the thick alluvium caving arch and the towering roof beam, which illustrates the whole process of water–sand inrush accidents in thin bedrock stope with deep thick alluvium.

Evaluation of Renewable Water Resources and Estimating of Aquifer Parameters in Wadi Hubuna, Southwestern Part of Saudi Arabia

Water is one of the most vital natural resources in the Kingdom of Saudi Arabia and crucial for the survival of all living organisms; it is essential for agriculture, industry, and domestic uses such as drinking and cooking. This study aims to conduct a hydrogeological study to determine the hydraulic parameters of the aquifer, besides evaluating the renewable water resources for Wadi Hubuna in the southern Arabian Shield. Twenty dams were constructed to recharge renewable water resources in the wadi deposits aquifer, with a total capacity of 10.139 MCM. The depths of the examined wells in this study ranged from 9.6 m (well HAB10) to 79 m (well HAB21). The static water level also varies from 2.5 m at well HAB14 to 79.19 m at well HAB17. Alluvium thickness varies from 9.6 m at well HAB10 to 51.7 m at well HAB17. The saturated thickness ranges from 4.4 m in HAB2 to 27.6 m in HAB11. The results of a step and continuous pumping test conducted on ten wells revealed that the well loss varies from 0.03 m at well HAB03 to 5.52 m at well HAB02, the aquifer loss varies from 0.22 m at well HAB03 to 2.84 m at well HAB11, the transmissivity varies from 1.86 x 10-4 m2/s at well HAB01 to 1.25 x 10-2 m2/s at HAB03 well, and finally, the hydraulic conductivity varies from 3.54 x 10-5 at well HAB01 to 1.72 x 10-3 at well HAB03. The western, southern, and northern parts of the wadi are rated low and extremely low in renewable groundwater potentiality because of the limited width of the wadies, the thin surface sediment layer, and the little recharge from rainfall. In order to monitor the water levels in Wadi Hubuna and Wadi Sar, it is required to drill a series of piezometers along their lengths.

Traces around a capital: the hinterland of Ravenna through remote sensing

Remote sensing has been a fundamental tool in reconstructing the urban landscape of the abandoned Late Antique city of Classe, near Ravenna (Italy). However, much of Classe urban plan is not yet known, while the vast area north of Ravenna has been generally ignored for the presence of thick alluvial deposits. The number of freely available aerial and satellite images has increased exponentially in the past decade, yet no study has exploited these sources. The features mapped by analysing these sources allowed us to identify new structures in Classe and shed new light on water management and land-use practices around Ravenna.

Characterization and Productivity of Alluvial Aquifers in Sustainability Oasis Areas: A Case Study of the Tata Watershed (Southeast Morocco)

Groundwater from alluvial aquifers is a critical source of water supply for rural agriculture, particularly in semi-arid and arid regions. Effective management of these aquifers requires an understanding of the factors that influence their water resources. In this study, we present a case study of the Tata watershed in southeastern Morocco, where the economy is heavily dependent on agriculture and relies exclusively on groundwater. We demonstrate the importance of integrating geological, hydrogeological, and geophysical methods to characterize the aquifer and evaluate groundwater productivity. Analysis of 64 data wells tapping into the aquifer revealed significant disparities in flow yields, ranging from 0.05 to 15.50 L per second. The highest yields were found between depths of 12 and 43 m, which correspond to the alluvium and the altered and fractured part of its substrate. The maximum alluvial thickness of 57 m was determined using geo-electrical prospecting. A piezometric map was created to define the recharge zones, which correspond to the lateral contributions of the bordering Georgian limestones, and infiltration of both rain and surface water along the Tata wadi. Since 1987, there has been a continuous drop in groundwater level, which can be attributed to the increase in irrigated areas following financial incentives provided by the Moroccan government to the agricultural sector. A proposal has been made for the construction of a recharge dam to enable the recharge of the alluvial aquifer. This development is expected to serve a dual purpose by mitigating the deleterious impacts of flooding and facilitating the gradual water infiltration of the alluvial aquifer. This case study provides insights into the hydrodynamics of the aquifer and establishes a simplified model of its functioning. These findings have important implications for the management of alluvial aquifers in similar regions.

PLACER DEPOSITS OF DIAMONDS AND THEIR FORMATION CONDITIONS

This article reviews information from published papers and studies by the authors about placer diamond deposits. Original data were obtained in result of field and laboratory-analytical work carried out in various countries of Africa and South America. The main types of placer diamond deposits – fluvial, fluvioglacial, eolian, and man-made – have been considered and characterized. The main attention is given to fluvial continental placers, which are the most diverse, well-studied and have the greatest industrial importance. Primary, secondary and mixed deposits are distinguished according to the method of feeding; short, moderate and long transport deposits – according to the distance of the diamond-bearing material movement. It is noted that although the short transport placers (deluvial-proluvial and beds of short watercourses) have not industrial value, they are very informative for the searching for root sources. It is important to reliably diagnose these deposits by lithological-facies and mineralogical features during prospecting works. The concepts about the conditions for the formation of diamond placers in various landscape and geological conditions are developed and clarified. Alluvial-proluvial-lacustrine and proluvial-lacustrine types of placers studied in Yakutia and Brazil are characterized in detail. Their characteristic feature is that their productive strata, being re-deposited products of crustal weathering, themselves underwent a hypergenic change at the place of occurrence, which significantly masks the primary conditions of formation. Continental alluvial redeposition and long transport placers, as well as marine, yield the most high-quality expensive diamonds, the average value of which can reach $300–400 per carat. Often, such placers are formed due to the erosion of ancient Proterozoic placers, which belong to the category of fossils. The article summarizes the genetic and morphological types of diamond placers in the form of a principle diagram of the distribution of sedimentary reservoirs of kimberlite minerals. The landscape-dynamic zones of sedimentation are highlighted. A classification scheme of sedimentary reservoirs containing diamond placers has been developed. Continental, transitional and marine environments are distinguished, with further detalization of sedimentation environments – peneplain, alluvial-lacustrine accumulative plain, alluvial-deltaic plain and shelf zones of sea basins. It is shown that the formation of valley placers, their internal structure, thickness, granulometric composition and diamond content of alluvium are influenced by the dynamic phases of the formation of annual valleys. Visualization of the mutual relationship of different morpho-genetic types of placer diamond deposits is given.

Geological investigation in the Bhuleshwari River Basin, Amravati District, Maharashtra

The Bhuleshwari river basin covers an area about 380 Sq. Km. from Bhatkuli and Achalpur Taluka, Amravati district, Maharashtra. It flows over varied geological formation from Deccan trap to Alluvium with groundwater quality varying from fresh water to saline water. The area has been studied to evaluate the impact of geomorphology on groundwater occurrence and its impact on hydrogeochemical evolution of groundwater. Number of field traverses and observation in the bank sections of the river and dug wells has been done in the given basin. The nature and lateral and vertical extent of aquifers are controlled by lithology, stratigraphy and structure of rock formations. Lithological characteristics of rocks are reflected in their storage and yield properties. The present work deals with the regional as well as local geological set of the area and its Stratigraphic position. It also deals with the lithological characteristics of the ‘basalt flows’ and structural features of the area. The detailed geology of the Bhuleshwari river basin has been discussed and presented in chapter two. Based on number of field traverses, in the geological map eight lavaflows has been identified in northern region and alluvium in southern region can be divided into younger and older alluvium. The Deccan trap is separated by alluvium with fault, boulder alluvium is seen to occur in this zone. The geological map of Bhuleshwari river basin modified from geological survey of India map, GSI (2001) is presented. Geologically the study area consists of 420 m thick Alluvium. Only the top 40 m is accessible for direct observation in the bank sections of the river and dug wells.

Overburden Breaking Law and Safe Mining Technology in Thin Bedrock Stope with Thick Alluvium

For the thick alluvium and thin bedrock coal seam mining in East China, it is easy to produce water by pressing the frame. Taking the engineering geological conditions of the thin bedrock coal seam 1611 (3) working face in the Zhangji Coal Mine of Huainan Mining Group as the research background, the breaking law of the thin bedrock coal seam working face with thick alluvium was studied by using a similar material physical simulation experiment and theoretical analysis. It is revealed that under the load transfer of the loose aquifer, the roof fracture of the stope with thick alluvium and thin bedrock is characterized by large and small periodic ground pressure, and the combination failure of the high key stratum and the low key stratum with large cycles is prone to support crushing accidents. Based on this, the safety mining technical measures of reducing the fracture distance of the high key stratum by forced roof caving are proposed, and the reasonable blasting parameters are calculated. After field application, no support crushing accident on the working face was recorded, and the mining was safe, which provides a technical reference for the mining of the working face under similar conditions.