scholarly journals Effect of geological and technological parameters on the convergence in a stope

2021 ◽  
pp. 16-22
Author(s):  
S.F Vlasov ◽  
Ye.V Moldavanov
Keyword(s):  
Rock Mass ◽  
Numerical Experiments ◽  
Computer Modelling ◽  
Main Roof ◽  
Wall Rock ◽  
Extraction Column ◽  
Technological Parameters ◽  
Mining Depth ◽  
Powered Support ◽  
Solid Works

Purpose. To study regularities in changes in convergence of wall rocks along a setting line of the powered props depending upon the sandstone availability within the roof, mining depth, as well as its position relative to the coal seam along the length of the extraction column based on the results of numerical experiments and forecast probable zones of rigid settlement of the powered support units according to a longwall length at any moment of a stope arrangement along the extraction pillar in accordance with changes in geological and technological parameters. Methodology. The paper represents numerical experiments based upon 3D computer modelling of incremental stope advance within a layered transverse and isotopic rock mass while applying Solid Works Simulation 2019 software. Findings. The research results, concerning the nature of wall rock distribution value within a stope, are given. The results were obtained using incremental computer modelling of the longwall advance within a layered transverse and isotopic rock mass within the area of initial caving of the main roof. Originality. In the context of the Western Donbas mines, regularities of convergence value of wall rock distribution have been determined depending upon certain changes in such a system of geological and technological parameters as: availability of sandstone with 5 and 30 m thickness both within the immediate rock and at 30 m distance as well as nonavailability of sandstone within a roof; 215, 260 and 305 m changes in longwall length; 150, 300 and 450 m changes within a zone of initial caving of the main roof (1545 m) with 10 m increment of longwall distancing from an installation chamber at 1050 m distances. Practical value. The identified regularities of changes in convergence value make it possible to forecast probable zones of rigid settlement of the powered support units depending upon the longwall length at any moment of a stope location along the extraction pillar irrespective of mining depth. The abovementioned helps optimize the parameters of seam extraction for the conditions of the Western Donbas mines if required.

Study on Surrounding Rock Pre-Stressed Crossed Anchor Control Technology in Roadway with Large Mining Depth

2012 ◽  
Vol 524-527 ◽  
pp. 471-475
Author(s):  
Xi Gui Zheng ◽  
Qin Jian Zhan ◽  
Bin Wang
Keyword(s):  
Rock Mass ◽  
Stress Distribution ◽  
Triaxial Compression ◽  
Soft Rock ◽  
High Strength ◽  
Wall Rock ◽  
Difficult Problem ◽  
Mining Depth ◽  
Rock Creep ◽  
Drainage Pipe

Based on the deep soft rock creep mechanism, according to the physical characteristics of bauxitic mudstone in ingate at the level of -1015 m of Kong Zhuang colliery, we solved the technical difficult problem of choosing anchor points of soft rock supporting roadway in ingate. Using high strength and low relaxation steel strand to reinforce by crossed anchor, in combination with the depth hole grouting technology, improve pressure-bearing capacity of wall rock in the ingate, safe passage and drainage pipe area. We analyze the stress distribution characteristics of rock mass, contrasting on the stress distribution at the end of partially grouted bolt and the rock mass. Practice shows that crossed anchor rock mass has triaxial compression over all, the bunch body has a single structure, and it is easily to be analyzed. We not only control the roof settling in the area of ingate is, but also solve the floor heave problem in safe passage and drainage pipe area.

Influence exerted by underground excavation shape and by effective stresses on the formation of a tensile strain zone at a depth greater than 1 km

2020 ◽  
pp. 67-75
Author(s):  
Van Min Nguyen ◽  
V. A. Eremenko ◽  
M. A. Sukhorukova ◽  
S. S. Shermatova
Keyword(s):  
Rock Mass ◽  
Cross Sections ◽  
Tensile Strain ◽  
Rock Fracture ◽  
Strain Analysis ◽  
Surrounding Rock ◽  
Underground Excavation ◽  
Secondary Stress ◽  
Principal Stresses ◽  
Mining Depth

The article presents the studies into the secondary stress field formed in surrounding rock mass around underground excavations of different cross-sections and the variants of principal stresses at a mining depth greater than 1 km. The stress-strain analysis of surrounding rock mass around development headings was performed in Map3D environment. The obtained results of the quantitative analysis are currently used in adjustment of the model over the whole period of heading and support of operating mine openings. The estimates of the assumed parameters of excavations, as well as the calculations of micro-strains in surrounding rock mass by three scenarios are given. During heading in the test area in granite, dense fracturing and formation of tensile strain zone proceeds from the boundary of e ≥ 350me and is used to determine rough distances from the roof ( H roof) and sidewalls ( H side) of an underground excavation to the 3 boundary e = 350me (probable rock fracture zone). The modeling has determined the structure of secondary stress and strain fields in the conditions of heading operations at great depths.

scholarly journals Influence of Gating System Parameters of Die-Cast Molds on Properties of Al-Si Castings

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3755
Author(s):  
Štefan Gašpár ◽  
Tomáš Coranič ◽  
Ján Majerník ◽  
Jozef Husár ◽  
Lucia Knapčíková ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Computer Modelling ◽  
Permanent Deformation ◽  
Surface Hardness ◽  
Technological Parameters ◽  
Inlet System ◽  
Die Cast ◽  
Key Factor ◽  
Fine Grained Structure ◽  
Design Solutions

The resulting quality of castings indicates the correlation of the design of the mold inlet system and the setting of technological parameters of casting. In this study, the influence of design solutions of the inlet system in a pressure mold on the properties of Al-Si castings was analyzed by computer modelling and subsequently verified experimentally. In the process of computer simulation, the design solutions of the inlet system, the mode of filling the mold depending on the formation of the casting and the homogeneity of the casting represented by the formation of shrinkages were assessed. In the experimental part, homogeneity was monitored by X-ray analysis by evaluating the integrity of the casting and the presence of pores. Mechanical properties such as permanent deformation and surface hardness of castings were determined experimentally, depending on the height of the inlet notch. The height of the inlet notch has been shown to be a key factor, significantly influencing the properties of the die-cast parts and influencing the speed and filling mode of the mold cavity. At the same time, a significant correlation between porosity and mechanical properties of castings is demonstrated. With the increasing share of porosity, the values of permanent deformation of castings increased. It is shown that the surface hardness of castings does not depend on the integrity of the castings but on the degree of subcooling of the melt in contact with the mold and the formation of a fine-grained structure in the peripheral zones of the casting.

Estimation of rockburst wall-rock velocity invoked by slab flexure sources in deep tunnels

2014 ◽  
Vol 51 (5) ◽  
pp. 520-539 ◽  
Author(s):  
Shili Qiu ◽  
Xiating Feng ◽  
Chuanqing Zhang ◽  
Tianbing Xiang
Keyword(s):  
Rock Mass ◽  
Seismic Source ◽  
Friction Angle ◽  
Wall Rock ◽  
Assessment Method ◽  
Source Mechanism ◽  
Uniaxial Tensile ◽  
Roughness Coefficient ◽  
Support Design ◽  
True Triaxial

For rock support in burst-prone ground, the wall-rock velocity adjacent to the surface of underground openings is a vital support design parameter, and depends on the seismic source mechanism inducing rockburst damage. In this study, to estimate the wall-rock velocity evoked only by rock slab buckling (an important rockburst source mechanism), a comprehensive velocity assessment method is proposed, using an excellent slab column buckling model with a small eccentricity, which relies on a novel compressive or tensile buckling failure criterion of rock slab. The true-triaxial loading–unloading tests and rockburst case analyses reveal that rock mass slabbing induced by high rock stress has major impacts on the evolution and formation of buckling rockburst in deep tunnels. Using a method based on the energy balance principle, the slabbing thickness of intact rock mass is also calculated by an analytical method, which indicates that the slabbing thickness parameter has a nonlinear relation to the following six parameters: uniaxial tensile strength (UTS), uniaxial compressive strength (UCS), normal stress (σn), length of joint (L), friction angle ([Formula: see text]), and joint roughness coefficient (JRC). These proposed models and methods have been quite successfully applied to rockburst and slabbing cases occurring in deep tunnels. These applications show that slab flexure is an important source mechanism invoking high wall-rock velocities and leading to severe rockburst damages in the area surrounding deep tunnels.

scholarly journals Determination of the Ultimate Underground Mining Depth considering the Effect of Granular Rock and the Range of Surface Caving

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Rongxing He ◽  
Jing Zhang ◽  
Yang Liu ◽  
Delin Song ◽  
Fengyu Ren
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Mechanical Model ◽  
Surface Deformation ◽  
Underground Mining ◽  
Mining Area ◽  
Open Pit ◽  
Open Pit Mining ◽  
Mining Depth

Continuous mining of metal deposits leads the overlying strata to move, deform, and collapse, which is particularly obvious when open-pit mining and underground mining are adjacent. Once the mining depth of the adjacent open-pit lags severely behind the underground, the ultimate underground mining depth needs to be studied before the surface deformation extends to the open-pit mining area. The numerical simulation and the mechanical model are applied to research the ultimate underground mining depth of the southeast mining area in the Gongchangling Iron mine. In the numerical simulation, the effect of granular rock is considered and the granular rock in the collapse pit is simplified as the degraded rock mass. The ultimate underground mining depth can be obtained by the values of the indicators of surface movement and deformation. In the mechanical model, the modified mechanical model for the progressive hanging wall caving is established based on Hoke’s conclusion, which considers the lateral pressure of the granular rock. Using the limiting equilibrium analysis, the relationship of the ultimate underground mining depth and the range of surface caving can be derived. The results show that the ultimate underground mining depth obtained by the numerical simulation is greater than the theoretical calculation of the modified mechanical model. The reason for this difference may be related to the assumption of the granular rock in the numerical simulation, which increases the resistance of granular rock to the deformation of rock mass. Therefore, the ultimate underground mining depth obtained by the theoretical calculation is suggested. Meanwhile, the surface displacement monitoring is implemented to verify the reasonability of the ultimate underground mining depth. Monitoring results show that the indicators of surface deformation are below the critical value of dangerous movement when the underground is mined to the ultimate mining depth. The practice proves that the determination of the ultimate underground mining depth in this work can ensure the safety of the open-pit and underground synergetic mining.

SUBSTANTIATION OF PARAMETERS OF THE EXPERIMENT WITH THREE-DIMENSIONAL COMPUTER MODELING OF THE ROCK MASS AROUND A LONGWALL

2021 ◽  
pp. 37-48
Author(s):  
Sergey Vlasov ◽  
◽  
Yavhen Moldavanov ◽  
Keyword(s):  
Rock Mass ◽  
Computer Modeling ◽  
Coal Mining ◽  
Three Dimensional ◽  
Mining Area ◽  
Practical Significance ◽  
Coal Seams ◽  
Working Face ◽  
Powered Support ◽  
The Difference

Purpose. To substantiate the parameters of computer modeling of the mining area with a step-by-step movement of the working face, as well as taking into account the changing presence of sandstones that lie in the top of the reservoir, to predict the effect of sandstones on the nature of the distribution of convergence in the longwall and the technology of working excavation in the conditions of the mines of Western Donbass. Methods. The work uses a statistical analysis of the geological and technological conditions that are inherent in the coal mining enterprises of the Western Donbass. Also, a comparison was made of the parameters of the experiment of computer modeling of past studies, on the basis of which, a combination of new features was introduced and changed, which is aimed at choosing the optimal modeling parameters. Results. The substantiation of the parameters of the modeling experiment is presented, such as: the choice of the length of the working face, the depth of development of coal seams, the distance of the working face withdrawal from the assembly chamber, the values of the thickness of sandstones that lie in the roof of the coal seams, the choice of values of the distance of occurrence of sandstones above the roof of the coal seam, as well as geometric parameters of the computer model. Based on the justification of the parameters, a plan for conducting experiments was drawn up, the number of which was 225 units. Scientific novelty. As a result of the substantiation of the parameters, an additional combination of new features in existing studies was proposed for the first time, namely, to include in the experiment the presence of coal seams in the top – sandstones with variable thickness, the distance of occurrence above the seam, several standard sizes of the length of the working face were also included, the value of the development depth, the distance of the exit of the working face from the assembly chamber. Changing the above parameters will make it possible to compare the difference in the effect of the results of each experiment separately, depending on the change in each of the parameters, as well as to understand and generalize the idea of ​​the nature and causes of emergency longwall stops associated with the landing of powered support sections “on a hard base”. Practical significance. Substantiated modeling parameters make it possible to most adequately reflect the processes occurring in the rock mass, as well as to clarify the parameters of the reference rock pressure zones, unloading zones, as well as the nature of the change in the distribution of convergence in the longwall. The data obtained as a result of modeling can be used to select and substantiate an effective method for managing the state of the rock mass around the working excavation, which will eliminate the planting of powered support sections “on a hard base”, thereby increasing the efficiency of coal mining in the Western Donbass.

Numerical Simulation of Advanced Small Pipe in Tunnels during Excavation by Steps

2013 ◽  
Vol 353-356 ◽  
pp. 3699-3702
Author(s):  
Chang Yu Jin ◽  
Zi Feng Xia ◽  
Chun Fu Xiang ◽  
Long Bin Dong ◽  
Pan Pan Zhao ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Wall Rock ◽  
Support Effect ◽  
Surrounding Rock ◽  
Tunnel Engineering ◽  
Engineering Construction ◽  
Support Mechanism ◽  
Deterioration Model ◽  
Advanced Support

Advanced small pipe support is one of the advanced support patterns in tunnel engineering construction for weak and fractured surrounding rock. The support effect cannot be predicted because of depending on engineering experiences. Efforts are made to study and analyze the support mechanism of advanced small pipe in the excavation of soft - fracture wall rock. By the numerical simulation of FLAC3D of Dawangou tunnel based on rock mass deterioration model (RDM), the plastic zone, displacement and stress filed of the surrounding rock are simulated with and without the advanced small pipe support. The support effect of advanced small ducts in tunnels during excavation by steps is presented.

scholarly journals The Effects of Material’s Transport on Various Steps of Production System on Energetic Efficiency of Biodiesel Production

2018 ◽  
Vol 10 (8) ◽  
pp. 2736 ◽  
Author(s):  
Olga Orynycz ◽  
Antoni Świć
Keyword(s):  
Production System ◽  
Production Systems ◽  
Computer Modelling ◽  
Raw Materials ◽  
Load Capacity ◽  
Biodiesel Production ◽  
Biofuel Production ◽  
Energetic Efficiency ◽  
Technological Parameters ◽  
Plantation Yield

Rapeseed plantation biodiesel production systems require the transportation of goods, like raw materials, machines and tools, and products between various conversion stages of agricultural as well as industrial subsystems. Each transportation step requires the consumption of some energy. This consumption decreases the net amount of energy delivered out of the biofuel production system, and consequently decreases the energetic efficiency of the system. The majority of studies on biofuel sustainability are done by means of the LCA method with the use of a data average for some region and period of time. Such analyses do not reveal the possible causes of the conclusions determined. The present work deals with computer modelling of the influence of the energy consumed on those transport routes on the energetic efficiency of the production system. The model enables determination of the effects caused by changes introduced to technological parameters. The effects caused by variation of fuel consumption, the load capacity of transportation means, size of plantation, distribution and sizes of individual fields, distances between fields, plantation yield, and finally the distance between the plantation and the industrial facility are studied using the numerical model developed earlier. This approach is aimed towards identifying the reasons for the behavior of a system controlled by many somewhat coupled variables.

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