scholarly journals DETERMINATION OF PARAMETERS OF DETACHED ROCK PACKS WITH COMPENSATION VOIDS

2020 ◽  
pp. 58-71
Author(s):  
Serhii Nehrii ◽  
◽  
Tetiana Nehrii ◽  
Ihor Yefremov ◽  
◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Soft Soil ◽  
Longitudinal Axis ◽  
Practical Significance ◽  
Stress Strain ◽  
Protection Measures ◽  
Numerical Studies ◽  
The Stability ◽  
Determination Of Parameters

Purpose: To determine the parameters of detached rock packs with compensating voids. Methodology: Analysis of technologies for the protection of development workings, based on the management of the stress-strain state of rocks around the workings, physical modeling using equivalent materials, numerical modeling by the finite element method, and methods of structural mechanics. Results: In the conditions of soft soil rocks the expediency of application of protection means based on management of a stress-strain condition in a surrounding massif and redirection of extrusion forces from a working has been substantiated. On the basis of analysis of the existing protection measures of the workings behind faces the prospects of use of protection technologies by means of construction of detached rock packs with limiting surfaces between which there are compensatory voids left, have been proved. To determine the parameters of such packs and voids between them in the conditions of soft soil rocks, a set of laboratory and numerical studies has been performed. According to their results, it has been established that to ensure the redirection of extrusion forces from the working it is necessary to build rock packs with limiting surfaces in the form of rectangular parallelepipeds with orientation of their greater side perpendicular to the longitudinal axis of production and trapezoidal prisms with their narrower orientation towards the working. Recommendations on the parameters of these structures and compensatory voids between them in the conditions of soft soil rocks have been formulated. Scientific novelty: On the basis of numerical modeling the regularities of stress distribution in rocks under detached rock packs of different shapes have been investigated, which allowed substantiating the parameters of the last and compensatory voids between them to ensure the stability of workings in the soft soil rocks. Practical significance: The expediency of application of technologies of protection of preparatory workings behind faces in the conditions of soft soil rocks by means of rock packs with limiting surfaces between which there are compensatory voids has been proved, and their parameters have been defined.

scholarly journals Modeling the stress-strain state of of a municipal solid waste landfill

Vestnik MGSU ◽  
2020 ◽  
pp. 776-788
Author(s):  
Vadim G. Ofrikhter ◽  
Galina M. Batrakova ◽  
Natalia N. Sliusar
Keyword(s):  
Numerical Modeling ◽  
Municipal Solid Waste ◽  
Solid Waste ◽  
Strain State ◽  
Soft Soil ◽  
Creep Model ◽  
Stress Strain ◽  
Waste Landfill ◽  
Stress Strain State ◽  
Soil Creep

Introduction. The process of municipal solid waste (further MSW) generation is inextricably linked with the life of humanity. Every day each person generates some, a small amount of garbage. As a result millions of tons of MSW are generated daily in the world which are unsuitable for further use and require disposal. There are various ways of handling MSW including their treatment, recycling and disposal. In Russian Federation the vast majority of MSW are currently located on the specially equipped facilities –– waste landfills. To date the most common waste management strategy remains their placement in a landfill. Waste landfills are arrays of stored waste and are special engineering structures designed for the safe isolation of their contents from the environment. Landfill includes gas exhaust and leachate drainage systems, liner and cover systems. The main component of this structure is waste itself. Mechanical stability of landfills should be provided at all stages of waste storage as well as after it complete filling to designed capacity and at post-closure stage. As the result of deformation of unstable waste, all landfill systems can be destroyed up to the collapse of garbage array leading to the significant environmental and other consequences. One of the most common problems leading to the various incidents at landfills is an incorrect assessment of their stability. MSW landfill is a complex multiphase system in which various interacting processes occur simultaneously. The main factor in the calculation and design of landfills is the forecast of their settlements. Studies by many authors have established that biological decomposition has a significant impact on the properties of MSW after which the waste is considered as the landfill soil with a particle size of up to 20 mm. Materials and methods. The paper presents the methodology and the results of numerical modeling of stress-strain state of the designed object “Waste Landfill”. The facility is an array of municipal solid waste of 38 meters high. Waste is stacked in the layers of 1.75 m thick. Each waste layer is covered by the loam cover of 0.25 m thick. Stress-strain state of municipal solid waste including biological creep was modelled using well-known “Soft-Soil-Creep model” (SSC-model). Results. The results of numerical simulation of stress-strain state of the waste pile at all stages of the filling and in the post-closure period are presented. An assessment of the increase in the capacity of the landfill due to the compaction and biological creep has been performed. Stability analysis of the landfill and potential failure mechanisms at different stages of filling and operation are presented. Conclusions. Numerical modeling of stress-strain state of the MSW array using the “Soft-Soil-Creep model” allows to analyze the stability of the waste pile at any stage of landfill filling and evaluate the increase in landfill capacity due to the waste settlement taking into account the mechanical creep and biocompression during layer-by-layer filling.

scholarly journals ANALISIS STABILITAS MENGGUNAKAN MODEL MATERIAL PERALIHAN TANAH-BATUAN

2019 ◽  
Vol 1 (3) ◽  
pp. 225-230
Author(s):  
Putera Agung ◽  
Ardianto A
Keyword(s):  
Stability Analysis ◽  
Friction Stress ◽  
Model Material ◽  
Dam Construction ◽  
Stress Strain ◽  
Angle Of Internal Friction ◽  
Analysis Of Stability ◽  
The Stability ◽  
Selection Of

AbstractAn analysis of stability needs to predict stress-strain values of soil, rock, and/or intermediate material (soil-rock) layers around the gate shaft during excavation works. Selection of stress-strain of intermediate material foccused on this paper will affect to the analysis result. This analysis concerned on some consideration to the selection the stress-strain parameters in determination of c’ and f’ parameters. In excavation works,the parameters were applied to the stability analysis of gate shaft construction of dam construction. The stability analysis used a 2 D software of PLAXIS. Each condition of gate shaft was reinforcement and un-reinforcement wall types. From several analyses, the parameters of c’ and f’ from stress-strain of soil was smaller than intermediate material.Keywords: Cohesion; angle of internal friction, stress, strain, gate shaft.Abstrak Suatu analisis stabilitas perlu untuk memperkirakan besarnya tegangan-regangan tanah, batuan, dan atau lapisan material peralihan tanah-batuan (intermediate material) di sekitar lubang galian vertikal. Pemilihan tegangan-regangan dari material peralihan tanah-batuan yang difokuskan pada paper ini akan berpengaruh terhadap hasil analisis. Analisis ini memusatkan perhatian pada beberapa pertimbangan pemilihan parameter tegangan-regangan dalam analisis stabilitas saluran pengalihn vertikal pada konstruksi dam. Analisis stabilitas ini menggunakan software Plaxis 2 D (dimensi). Masing-masing tipe dinding saluran vertikal ini adalah dengan dan tanpa perkuatan tulangan. Dari beberapa analisis, parameter c’ dan f’ dari tanah adalah lebih kecil dari material peralihan.  Katakunci: Kohesi, sudut geser dalam, tegangan, regangan, saluran pengalihan vertikal.

scholarly journals Influence of breakages of cable groups on strength ofrubber-cable tractive-transporting element

2021 ◽  
Vol 64 ◽  
pp. 166-174
Author(s):  
I Belmas ◽  
D Kolosov ◽  
O Dolgov ◽  
H Tantsura ◽  
S Onyshchenko
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Strain State ◽  
Elastic Shell ◽  
Practical Significance ◽  
Analytical Determination ◽  
Shear Stresses ◽  
Stress Strain ◽  
Stress Strain State

Purpose. Development and justification of a method of analytical determination of a stress-strain state of a flat rubber-cable tractive-transporting element with breakages of continuity of cable groups in different cross-sections. Methodology of research is in development of a mathematical model of interaction of tractive-transporting element parts considering breakages of groups of random cables, construction of analytical solutions for determining dependencies of force distribution between cables and shear stresses in an elastic shell of a tractive-transporting element with random locations of breakages of cable groups in different cross-sections. Findings. A model of a flat rubber-cable tractive-transporting element with random locations of breakages of cable groups in different cross-sections is developed. Expressions that allow determining a stress-strain state of a flat rubber-cable tractive-transporting element of a hoisting and transporting machine with random locations of breakages of cable groups in different cross-sections are obtained analytically in a closed form. Strength conditions are formulated. Scientific novelty is in establishment of dependencies of interaction of disturbance fields of a stress-strain state of a rubber-cable tractive-transporting element with breakages of continuity of random cable groups in different cross-sections. It is established that disturbance fields caused by breakages of adjacent cables overlap when the breakages are located in one cross-section and there are less than three whole cables located between the broken cables. Disturbance fields also overlap when the same cable or the adjacent cable is broken in both cross-sections and the distance between cross-sections of breakage does not exceed the value, which depends on the design of a flat rubber-cable tractive-transporting element and mechanical properties of its components. Practical significance. The obtained algorithms and strength conditions allow determining a stress-strain state and preventing the breakage of the entire flat rubber-cable tractive-transporting element with breakages of cable groups in different cross-sections. These cross-sections can be: cross-section of the edge of a butt joint, where cables have breakages of continuity; cross-section, which includes the edge of an area of partial restoration of a tractive ability of the element, lost due to breakage of a cable; cross-section of cable or cable group breakage during operation. A possibility of establishing a stress-strain state and the strength conditions of a tractive-transporting element under such conditions allows reasonable determination of a possibility of its further operation in a hoisting and transporting machine.

scholarly journals Concrete-faced rockfill dams: experience in study of stress-strain state

Vestnik MGSU ◽  
2019 ◽  
pp. 207-224 ◽  
Author(s):  
Vladislav B. Soroka ◽  
Mikhail P. Sainov ◽  
Denis V. Korolev
Keyword(s):  
Numerical Modeling ◽  
Reinforced Concrete ◽  
Strain State ◽  
Stress Strain ◽  
Linear Character ◽  
Stress Strain State ◽  
Operation Conditions ◽  
Numerical Studies ◽  
Deformation Properties ◽  
The Impact

Introduction. At present the urgent problem in hydraulic construction is establishing the causes of crack formation in seepage-control reinforced concrete faces at a number of rockfill dams. For solving this problem the studies are conducted of stress-strain state (SSS) of concrete-faced rockfill dams which are fulfilled by different methods. Materials and methods. Gives a review and analysis of the results of studies of stress-strain state of concrete-faced rockfill dams (CFRD) fulfilled by different authors over the last 15 years. The results of analytical, experimental and numerical studies are considered. Descriptions are given of the models used for simulation of non-linear character of rockfill deformation at numerical modeling of dam SSS. Results. Analysis showed that solving the problem of CFRD SSS causes a number of methodological difficulties. At present the only method permitting study of CFRD SSS is numerical modeling. The rest methods do not permit considering the impact of important factors on SSS. Large complications are caused by scarce knowledge of rockfill deformation properties in real dams. Conclusions. It was revealed that at present SSS of reinforced concrete faces has been studied insufficiently. The results of conducted studies do not give full and adequate understanding about operation conditions of reinforced concrete faces. Impact of various factors on the face SSS has not been studied. Besides, there are contradictions in the results of studies obtained by different authors. Differences in the results are based on objective and subjective reasons. A considerable obstruction for numerical studies is complicated modeling of rigid thin-walled reinforced concrete face behavior at large deformations inherent to rockfill. The obtained results of studies often do not permit conducting full analysis of SSS of concrete-faced rockfill dams.

Sign in / Sign up

Export Citation Format

Share Document