scholarly journals Theoretical Analysis for Stability Evaluation of Rock Mass Engineering Structure under Combined Compression-Shear Loading: A Case Study of Inclined Pillar

2021 ◽  
Vol 11 (23) ◽  
pp. 11439
Author(s):  
Lijun Sun ◽  
Yicheng Ye ◽  
Binyu Luo ◽  
Nanyan Hu ◽  
Pengcheng Li
Keyword(s):  
Stress State ◽  
Theoretical Analysis ◽  
Bearing Capacity ◽  
Underground Mining ◽  
Stress Path ◽  
Systematic Investigation ◽  
Shear Loading ◽  
Shear Load ◽  
Strength Model ◽  
Ore Body

An inclined pillar is a typical support structure under compression and shear loads for underground mining. The shear load caused by the inclination of the ore-body affects the bearing capacity of the pillar. At present, there is no systematic investigation on the influence of shear load on the stress state evolution and bearing capacity of the inclined pillar. Additionally, there is still a lack of effective evaluation of the bearing capacity of the inclined pillar in the presence of additional shear load. In this research, the theoretical analysis method is used to solve these problems. First, the compressive and shear load components on the inclined pillar were calculated by the tributary area method, and the average stress state of the inclined pillar, considering the influence of the shear load, was characterized by a series of generalized stress circles. The factors that affect the shear load, such as the area extraction ratio, the inclination of the ore-body, and the in-situ stress ratio, were analyzed, and it reveals that there are three kinds of stress paths of the inclined pillar and their trajectories are straight line, circle, and curve, respectively. Then, a shear strength model was proposed to evaluate the bearing capacity of inclined pillars. The expression of this model is multiplied by a vertical pillar strength model and a dimensionless coefficient that is named the contribution factor of shear load (CFSL). Some cases of inclined pillars were employed to verify the rationality of this model. Finally, the factors that affect the bearing capacity of pillars were analyzed. This investigation presents that the shear load affects the stress path and determines the bearing capacity of the pillar. Therefore, the shear load should not be neglected in pillar design and stability analysis.

scholarly journals Simulation of deposit parameters in underground development mining

2018 ◽  
Vol 60 ◽  
pp. 00029 ◽  
Author(s):  
Vladimir Golik ◽  
Yuriy Razorenov ◽  
Volodymyr Morkun ◽  
Nataliia Morkun
Keyword(s):  
System Analysis ◽  
Physical Simulation ◽  
Underground Mining ◽  
Theory And Practice ◽  
Ore Body ◽  
Advanced Experience ◽  
Modern Development ◽  
Complex Criterion ◽  
Economic Indices ◽  
Equipment Application

The article is aimed at improving development mining to prepare an ore body for stoping by access ramps to provide comfortable conditions and high technical and economic indices in underground mining. Efficient parameters of underground mining are chosen in the course of simulating data on the mining theory and practice considering ore losses and dilution on the basis of critical analysis of uranium mining enterprises’ activities. The research provides data on geological and engineering zoning of an ore deposit and physical-mechanical properties of ore bearing rocks. The advanced experience is systemized and there is provided system analysis of modern development mining schemes with access ramps (ring, spiral, one-way inclined, central inclined and across the strike). The research recommends schemes of development mining and substantiates their advantages. There are quantitative indices of physical simulation of development variants as to drawn ore quality according to criteria of soil location in ore draw points. The scientific novelty implies developing the criterion of optimality and ranking variants of development mining according to technical-economic and geomechanical indices considering some technological factors as well as the number of stopes operating simultaneously on the level. The study consists in increasing authenticity of development projects through applying complex schemes of access ramps according to the complex criterion of increasing mining depths, equipment application, ventilation and underground mine capacity.

Study on the Best Reinforcement Arrangement of Thick-Walled Cylinder

2011 ◽  
Vol 94-96 ◽  
pp. 2009-2014
Author(s):  
Yun Qian Xu ◽  
Ai Zhong Lu ◽  
Ning Zhang ◽  
Pan Cui
Keyword(s):  
Stress State ◽  
Bearing Capacity ◽  
Functionally Graded Material ◽  
Radial Direction ◽  
Plain Concrete ◽  
Functionally Graded ◽  
Reinforcement Ratio ◽  
Uniform Load ◽  
Graded Material ◽  
Walled Cylinder

In order to improve the ultimate bearing capacity, In this paper, the theory of functionally graded material is introduced. This paper simulate thick-walled cylinder with functionally graded characteristics through the analysis of using different reinforced ways along the radial direction. The author analyzes the stress state of the thick-walled cylinder with plain concrete and three different reinforced ways under the radical uniform load. Comparisons and evaluations are provided based on ANSYS results. The paper provide a reasonable reinforced way that is a larger reinforcement ratio near the outer and a smaller reinforcement ratio near the inner and is different with the traditional way. But the worst reinforcement arrangement is that a larger reinforcement ratio near the inner and a smaller reinforcement ratio near the outer. The conclusion shows that the principle that larger reinforcement ratio should be adopted where the tangential stress is larger is not suitable to the thick-walled cylinder.

Theoretical analysis on the bearing capacity of structural Steel Tube and Coupler Scaffolds

2015 ◽  
pp. 79-83
Author(s):  
Zhengran Lu ◽  
Yongqin Wen ◽  
Liang Zhao ◽  
Changtie Huang ◽  
Shuo Cao ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Bearing Capacity ◽  
Structural Steel ◽  
Steel Tube

scholarly journals Performance Analysis of Maximum Likelihood Estimation for Transmit Power Based on Signal Strength Model

2018 ◽  
Vol 7 (3) ◽  
pp. 38 ◽  
Author(s):  
Xiao-Li Hu ◽  
Pin-Han Ho ◽  
Limei Peng
Keyword(s):  
Maximum Likelihood ◽  
Performance Analysis ◽  
Theoretical Analysis ◽  
Numerical Experiments ◽  
Likelihood Estimation ◽  
Signal Strength ◽  
Strength Model ◽  
Transmit Power ◽  
Ml Estimation ◽  
Theoretical Performance

We study theoretical performance of Maximum Likelihood (ML) estimation for transmit power of a primary node in a wireless network with cooperative receiver nodes. The condition that the consistence of an ML estimation via cooperative sensing can be guaranteed is firstly defined. Theoretical analysis is conducted on the feasibility of the consistence condition regarding an ML function generated by independent yet not identically distributed random variables. Numerical experiments justify our theoretical discoveries.

scholarly journals NONLINEAR DEFORMATION-FORCE MODEL OF A CONCRETE BAR WITH NON-METALLIC COMPOSITE REINFORCEMENT IN THE GENERAL CASE OF A STRESSED STATE

2021 ◽  
Vol 3 (1) ◽  
pp. 6-26
Author(s):  
I. Karpiuk ◽  
◽  
Ye. Klymenko ◽  
V. Karpiuk ◽  
M. Karpiuk ◽  
...  
Keyword(s):  
Stress State ◽  
Stressed State ◽  
Bearing Capacity ◽  
Nonlinear Deformation ◽  
Complex Stress ◽  
Complex Stress State ◽  
Force Model ◽  
Metallic Composite ◽  
Aggressive Environment ◽  
Deformation Force

The article discusses a nonlinear deformation-force model of a concrete bar structure with a non-metallic composite reinforcement (NKA-FRP) in the general case of a stressed state, when all four internal force factors from an external load (namely, bending and twisting moments, transverse and longitudinal forces). A sufficiently deep and meaningful analysis of well-known studies on the selected topic is given. It has been established that the proposed nonlinear deformation-force model of a bar structure with FRP in the general case of a stressed state can be practically useful due to the possibility of its application in the design or reinforcement of beams, girders, columns and elements of rosette trusses of rectangular cross-section, which are operated under aggressive environmental conditions. This model can also be used to check the bearing capacity of existing FRP concrete bar structures, which operate not only under the influence of an aggressive environment, but also under conditions of a complex stress-strain state. In the course of the research, an algorithm was developed for determining the bearing capacity of the design section of a concrete rod with FRP under its complex stress state. General physical relations for the design section are given in the form of a stiffness matrix. The algorithm for calculating a concrete bar with FRP consists of a block for inputting the initial data, the main part, auxiliary subroutines for checking the conditions for increasing the load vector and depletion of the bearing capacity, as well as a block for printing the calculation results. At each stage of a simple static stepwise increasing load, the calculation is carried out by performing a certain number of iterations until the accuracy of determining all components of the deformation vector satisfies a certain predetermined value. The features and patterns of changes in normal and tangential stresses, generalized linear and angular deformations, as well as the equations of equilibrium of a concrete bar with FRP, which operates under the influence of an aggressive environment under conditions of a complex stress state, are also considered.

Casing Bearing Capacity with Shear Load for Shale Gas Wells

2020 ◽  
Vol 993 ◽  
pp. 1190-1195
Author(s):  
Shang Yu Yang ◽  
Jian Jun Wang ◽  
Jia Wen Han ◽  
Hang Wang ◽  
Li Hong Han
Keyword(s):  
Bearing Capacity ◽  
Shale Gas ◽  
Failure Modes ◽  
Oil And Gas ◽  
Evaluation Model ◽  
Radial Deformation ◽  
Shear Load ◽  
Gas Wells ◽  
Fracturing Process ◽  
Casing Deformation

Casing radial deformation during complex fracturing process was seriously for shale gas wells in Sichuan district of China, and the average casing deformation rate in the region is of 50%. The bridge plug, perforating gun and other tools cannot successfully pass with deformed casing. Aiming at the 3-D logging morphology for deformed casing of shale gas wells, the failure modes and mechanisms were analyzed by using elasticity and theoretical mechanics. Many factors were evaluated and integrated to achieve quantitative evaluation model including geology feature, wellbore trajectory, cement property, casing material and hydrofracture process. With the aid of the self-developed unconventional oil and gas well casing simulation test equipment, the casing bearing capacity with shear load were carried out, established the relationship between shear load value and radial deformation, and further constructed the casing failure criterion with shear force. This work can provide technical support for casing design and selection in shale gas wells.

scholarly journals A Predictive Model of Mining Collapse Extent and Its Application

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Jia Nan ◽  
Cheng Liu ◽  
Yi Liu
Keyword(s):  
Bearing Capacity ◽  
Evaluation Model ◽  
Water Environment ◽  
Slip Angle ◽  
Collapse Mechanism ◽  
Rock Body ◽  
Metal Mine ◽  
Ore Body ◽  
Grouting Reinforcement ◽  
Reinforcement Program

To reveal the mechanical behavior mechanism of collapse and to control risks effectively, the instability extent of the collapse area was established through theoretical mechanics and numerical methods, taking one metal mine as a case study; on this basis, a routine reinforcement program was determined, and the effect of the program was evaluated. The results show the following. (1) Analytical formulas of the critical slip angle and the collapse height of the ore body were derived by the mechanics method, and the rock mechanics parameters were obtained by field coring and physical and mechanical experiments. The slipping line angle increases along with uniform force Q and is inversely proportional to the bending stiffness. Meanwhile, the calculation formula for the maximum subsidence of ore body was deduced. (2) Numerical results can be used to determine the basic form of the collapse area, and a “U-shaped” collapse area formed when a plastic area passed completely through, resulting in the overall destruction. (3) The grouting reinforcement program includes “determining the instability region ⟶ roadway temporary support ⟶ improve the water environment and surrounding rock bearing capacity ⟶ mining planning” which were determined on the basis of prediction. (4) The hierarchical structure of the rock body and filling were improved combined with the Delphi method, and the grouting effect evaluation model was constructed and verified using the improved FD-AHP method; the evaluation value indicating that the grouting reinforcement improved the bearing capacity of ore body and filling body in collapse area. The research results provide systematic reference and technical support for the analysis of stope collapse mechanism, prediction of hidden trouble, and the subsequent mining.

scholarly journals Using Topographic Advantages in Formulating a Strategy to Access Ore Bodies at Ban Phuc Nikel Mine

2020 ◽  
Vol 174 ◽  
pp. 01013
Author(s):  
Hung Nguyen Phi ◽  
Thang Pham Duc
Keyword(s):  
Underground Mining ◽  
Mineral Deposit ◽  
Access Method ◽  
Near Surface ◽  
Ground Support ◽  
Mining Technique ◽  
Ore Body ◽  
Ore Bodies ◽  
Gain Access ◽  
Transport Potential

There are various types of underground mining that are categorized based on the kind of shafts used, the technique of extraction and the process used to get to a deposit. Development mining is composed of excavation almost entirely in (non-valuable) waste rock in order to gain access to the orebody. To start the mining, the first step is to make the path to go down. Development, the work of opening a mineral deposit for exploitation is performed. With it begins the actual mining of the deposit. Access to the deposit must be gained either by stripping the overburden, which is the soil and/or rock covering the deposit,to expose the near- surface ore for mining or by excavating openings from the surface to access more deeply buried deposits to prepare for underground mining. The type of underground mining technique used is typically based on the geology of the area, especially the amount of ground support needed to make mining safe. When using to exploit ore body by underground mining method, the textbook guide in universities of Vietnam had had 4 main strategies include: access by horizontal tunnel lines, access by incline shaft, vertical shaft and combination of above access method. In this study, we developed a solution outside of four above approaches, to take advantage of the topography, transport potential energy, and advantages when constructing sloped incline, backward from outside to inside.

scholarly journals Evolution Rules of Fractures for Mudstone under Compression Shear Load and the Fractal Characteristics of Broken Blocks

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Zhaoyun Chai ◽  
Jinbo Bai ◽  
Haiyang Zhang ◽  
Pan Yang
Keyword(s):  
Fractal Dimension ◽  
Compression Test ◽  
Shear Fracture ◽  
Fractal Theory ◽  
Friction Angle ◽  
Shear Loading ◽  
Shear Load ◽  
Deformation And Failure ◽  
Fractal Characteristics ◽  
Logarithmic Relationship

Failure of rocks is commonly induced by compressive and shear coupling loading. Knowledge of the mechanism and process of deformation and failure of rocks under compressive shear loading condition is an important basis for the study of stability in rock engineering. Based on the nonlinear fractal theory, it is possible to examine the evolution rules of fractures in mudstone under compression shear load and the fractal characteristics of broken blocks using the shear compression test with variable angles of mudstone specimens in natural conditions. This research shows that the cohesion and friction angle parameters of rock samples are achieved by draw Mohr’s strength envelope according to the test date of variable-angle shear compression test. It also shows that the shape of load-displacement curves of rocks can be divided into four stages: compaction, elastic, plastic, and fracture, and the curve can accurately represent the transformation and breakage characteristics of rock during shear fracture. And the distribution of broken blocks shows a strong statistical resemblance to the fractal distribution, and the fractal dimension is able to reflect the distribution characteristics of broken blocks. With increasing the shear angle, the fractal dimension of broken blocks decreases in a logarithmic relationship.

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