scholarly journals Monitoring and Analysis of Stress and Deformation Features of Boundary Part of Backfill in Metal Mine

2020 ◽  
Vol 12 (2) ◽  
pp. 733
Author(s):  
Rong Lu ◽  
Fengshan Ma ◽  
Jie Zhao ◽  
Jianbo Wang ◽  
Guilin Li ◽  
...  
Keyword(s):  
Stress Distribution ◽  
Peak Stress ◽  
Scientific Basis ◽  
Complex Stress ◽  
Ground Subsidence ◽  
Stress Monitoring ◽  
Mining Depth ◽  
Metal Mine ◽  
Backfill Mining ◽  
Boundary Part

The backfill mining method is widely used in metal mines. A large and thick backfill body has formed in the No.2 zone of Jinchuan Nickel Mine, and its stability is critical for mining safety. In order to study the mechanical behavior of the boundary part of backfill, ground subsidence monitoring, underground filed monitoring of displacement, and stress and numerical simulation were conducted to analyze stress distribution and deformation of backfill. According to underground monitoring, the bed separated displacement has the consistent trend with ground subsidence in the mine area. Based underground stress monitoring, both horizontal and vertical stress of the internal part of backfill is less than the stress boundary part of the backfill. The characteristic of backfill boundary outline is a step-profile. Contact interaction between the surrounding rock and backfill led to complex stress distribution. According to stress monitoring of the boundary points in a numerical model, the multi-peak value of stress development is the major feature of the boundary part of backfill. The multi-peak stress behavior of the boundary part of backfill was influenced by mining depth. The boundary part of backfill deformation influenced the local stability of mining. This article provided a scientific basis for strength design and the support choice of a metal mine by the method of backfill mining.

Research of the Connecting Form about the Spherical Shell and the Nozzle

2011 ◽  
Vol 413 ◽  
pp. 520-523
Author(s):  
Cai Xia Luo
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Finite Element Model ◽  
Spherical Shell ◽  
Maximum Stress ◽  
Peak Stress ◽  
Element Model ◽  
Small Opening ◽  
Large Opening ◽  
Reducing Stress

The Stress Distribution in the Connection of the Spherical Shell and the Opening Nozzle Is Very Complex. Sharp-Angled Transition and Round Transition Are Used Respectively in the Connection in the Light of the Spherical Shell with the Small Opening and the Large One. the Influence of the Two Connecting Forms on Stress Distribution Is Analyzed by Establishing Finite Element Model and Solving it. the Result Shows there Is Obvious Stress Concentration in the Connection. Round Transition Can Reduce the Maximum Stress in Comparison with Sharp-Angled Transition in both Cases of the Small Opening and the Large Opening, Mainly Reducing the Bending Stress and the Peak Stress, but Not the Membrane Stress. the Effect of Round Transition on Reducing Stress Was Not Significant. so Sharp-Angled Transition Should Be Adopted in the Connection when a Finite Element Model Is Built for Simplification in the Future.

scholarly journals Front Stress Distribution Under the Impact of Cutting Height to Caving Height Ratio in Extra-thick Longwall Top Coal Caving Technology

2020 ◽  
Vol 1 (2) ◽  
Author(s):  
Bui MANH TUNG ◽  
Nguyen VAN QUANG ◽  
Nguyen PHI HUNG ◽  
Vo NGOC DUNG ◽  
Do HOANG HIEP
Keyword(s):  
Stress Distribution ◽  
Peak Stress ◽  
Height Ratio ◽  
Research Orientation ◽  
Geological Conditions ◽  
The Face ◽  
New Research ◽  
Longwall Top Coal Caving ◽  
Cutting Height ◽  
The Impact

The extraction with higher cutting height for extra-thick seam is the new research orientation in longwall caving technology. Due to the increase of top coal thickness and of cutting height which leads to the change of cutting/caving height ratio, the rule of roof failure (including top coal caving) and the distribution of stress around the face alter correspondingly. This paper is based on the geological conditions of face 8102 of Tashan-DaTong mine, employing the numerical model by UDEC2D code, analysing the effect of cutting/caving height ratio on the law of stress distribution ahead of the face. When the ratio of cutting/caving height decreases and the cutting height increases, the results of the research have shown that: (i)- peak stress redistributes further ahead of the face and its value manifestly drops; (ii)- the plastic deformation ahead of face significant increases and the zone of plastic strain also expands. It is therefore concluded that the variation of cutting/caving height ratio results in the redistribution of roof pressure, which contributes to the control of roof failure and face stability.

Fatigue Evaluation Incorporating Multiaxiality of Stress States

2005 ◽  
Author(s):  
Somnath Chattopadhyay
Keyword(s):  
Stress Distribution ◽  
Stress Concentrator ◽  
Experimental Studies ◽  
Peak Stress ◽  
Thermal Fluctuations ◽  
Feed Water ◽  
Critical Factors ◽  
Water Nozzle ◽  
Stress States ◽  
Fatigue Evaluation

In this work the effects of multiaxiality on the fatigue evaluation by the ASME Boiler and Pressure Vessel Code procedures have been assessed. The conservatism associated with the Ke factor has been critically appraised for fatigue evaluation using a design example of a feed water nozzle subjected to pressure and thermal fluctuations. A fictitious stress concentrator is applied to account for the ratio of the peak stress to the stress linearized through the thickness of the section under consideration. The effect of the traxiality of the stress distribution has also been assessed using the same design example for fatigue evaluations. Additional analytical and experimental studies have been recommended to study these important critical factors for fatigue assessment.

scholarly journals Modeling for Distribution of Compressive Stress from Loading Platens in Diametrical Compression Test

2018 ◽  
Vol 250 ◽  
pp. 01009 ◽  
Author(s):  
Yukari Higashi ◽  
Shinnosuke Yoshinaga ◽  
Rini Asnida Abdullah ◽  
Takashi Tsutsumi
Keyword(s):  
Tensile Strength ◽  
Stress Distribution ◽  
Compressive Stress ◽  
Compression Test ◽  
Contact Area ◽  
Stress Function ◽  
Fourier Expansion ◽  
Complex Stress ◽  
Concentrated Loading ◽  
Indirect Tests

Diametrical Compression test is one of indirect tests to investigate the tensile strength of brittle materials. This test is spread because of easiness to perform. However, results from this test are not stable. Traditionally, calculations for this test are performed under a pair of opposite concentrated loading on the diameter of specimen. However, contact areas appear just before fracture of specimen in the fact and the stress distribution from loading platens is not obvious. It seems be one of reasons why the result from this test is not stable. In this study, the attempt to establish the modeling for distribution on loading platens in the diametrical compression test is shown. The aim of this modeling is to calculate stresses and displacement of specimen using complex stress function by Lekhnitskii. Therefore, this model is expanded in Fourier expansion. Accuracy of calculation using Fourier expansion depends on the number of terms. Therefore, the influence of contact area and number of terms to accuracy is also discussed.

Numerical Simulation of Vertical Ground Stress Distribution along Fault Trend Direction in a Metal Mine

2012 ◽  
Vol 204-208 ◽  
pp. 119-122
Author(s):  
You Xi Wang ◽  
Guang Zhe Deng
Keyword(s):  
Stress Distribution ◽  
Fault Zone ◽  
Hanging Wall ◽  
Fault Zones ◽  
Engineering Practice ◽  
Metal Mine ◽  
Deep Faults ◽  
Vertical Ground ◽  
Ground Stress ◽  
Trend Direction

The fault breaks continuous ground stress distribution. The rock mass in fault zone is weak and broken, it becomes stress decreasing zone. The paper, which is combined with engineering practice and rock mechanics test, numerically simulates geological environment of fault zones and analyzes faults trend direction influence on ground stress distribution in the metal mine. The results demonstrates that deep faults breaks down the continuity of ground stress distribution, principle stresses in lower wall of faults are smaller than it in hanging wall while high deep ground stresses are in cross district of hanging-wall of fault-zone and ore bed

scholarly journals A Method of Backfill Mining Crossing the Interchange Bridge and Application of a Ground Subsidence Prediction Model

Minerals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 945
Author(s):  
Shuaigang Liu ◽  
Jianbiao Bai ◽  
Gongyuan Wang ◽  
Xiangyu Wang ◽  
Bowen Wu
Keyword(s):  
Prediction Model ◽  
Dynamic Change ◽  
Simulation Software ◽  
Surface Subsidence ◽  
Ground Subsidence ◽  
Mining Method ◽  
Subsidence Prediction ◽  
Probability Integral Method ◽  
Backfill Mining ◽  
Step Distance

The traditional backfill mining method is a technology developed by the general trend of green coal mining, but with a high cost and an impact on production efficiency. This paper proposes a structured backfill mining method with high-water materials and pillars. The evolution of roof pressure appearance is assessed through the sensor and monitoring system in the hydraulic support. The main roof fracture step distance is determined based on the roof structure characteristics of backfill mining, and the backfill step distance of underground structural backfill is 22.7 m considering the safety factor. Through the simulation results of Abaqus commercial simulation software, the roof subsidence evolution of different backfill schemes under temporary load and permanent load is compared, and the rationality of the backfill step distance is verified. Based on the probability integral method, the surface subsidence prediction model is proposed, then the final value and the maximum dynamic change value of the surface subsidence at the north and south ends of the interchange bridge by traditional mining and backfill mining are analyzed, which verifies the rationality of the structural backfill mining method.

Further Studies of Stress Distribution in Rotating Disks and Cylinders Under Elevated-Temperature Creep Conditions

1958 ◽  
Vol 25 (2) ◽  
pp. 243-250
Author(s):  
A. M. Wahl
Keyword(s):  
Stress Distribution ◽  
Variable Thickness ◽  
Peak Stress ◽  
Rotating Disk ◽  
Average Stress ◽  
Solid Cylinder ◽  
Rotating Disks ◽  
Tangential Stresses ◽  
Rate Relation ◽  
Theoretical Results

Abstract The analysis previously given for stress in rotating disks having central holes and under steady-state creep conditions is extended to cases where the radial and tangential stresses are equal over all or a portion of the disk, both constant and variable-thickness cases being considered. In addition, the solid rotating disk and the long rotating solid cylinder are treated, peak stresses above the elastic values being found under certain conditions. Charts are presented for determining ratios σtm/σtav between peak stress and average stress, for various diameter ratios, disk contours, and values of n in the power-function stress-creep rate relation. These indicate somewhat lower ratios of peak to average stress for the variable-thickness disks. Based on the theoretical results, curves of stress distribution are also worked out for several typical cases.

Numerical Analysis of the Stress in Joggle Double Lap Joint

2012 ◽  
Vol 511 ◽  
pp. 150-153
Author(s):  
Xiao Ling Zheng ◽  
Ling Wu ◽  
Min You ◽  
Kai Liu ◽  
Cun Jun Chen
Keyword(s):  
Stress Distribution ◽  
Equivalent Stress ◽  
Peak Stress ◽  
Middle Part ◽  
Lap Joints ◽  
Lap Joint ◽  
The Finite Element Method ◽  
Adhesively Bonded ◽  
Von Mises Equivalent Stress ◽  
Von Mises

Both normal and joggle double lap joints were numerical analyzed to get the stress distribution in mid-bondline and in adherends near the interface using the finite element method (FEM). The results from the numerical simulation show that nearly all the peak values of the stress components as well as the von Mises equivalent stress distributed in both mid-bondline and adherend near the interface of the adhesively bonded joggle double lap joint are significantly decreased to the normal one. It was pointed out that the load bearing capacity of the joggle double lap joint may be higher than that of the double lap joint for its decrease of peak stress, much evenly stress distribution in the middle part of the overlap zone so that more load can be subjected by the joggle double lap joint.

Stress Distribution Near Internal Crack Tips for Longitudinal Shear Problems

1965 ◽  
Vol 32 (1) ◽  
pp. 51-58 ◽  
Author(s):  
G. C. Sih
Keyword(s):  
Stress Distribution ◽  
Stress Singularity ◽  
Crack Tip ◽  
Longitudinal Shear ◽  
Complex Stress ◽  
Internal Crack ◽  
Vertex Angle ◽  
Crack Tips ◽  
Bending Problems ◽  
Half Power

A method is developed for finding the stress distribution in a cracked body under longitudinal shear and applied to solve a number of problems. Stress solutions are obtained in closed form and discussed in connection with the Griffith-Irwin theory of fracture. The results indicate that current fracture-mechanics theories may be applied directly to longitudinal shear problems. More specifically, the character of the stress distribution near the vertex of a sector cylinder in shear is examined. The inverse half-power law of the stress singularity at a crack tip may be verified by taking a vertex angle of 2π. In addition, crack-tip, stress-intensity factors are defined and evaluated from a complex stress function in a manner similar to those previously given for extension and plate-bending problems. Results of such studies clarified the behavior of branched cracks and other crack systems of interest.

Effects of Local Peak Stress Distribution on the Ratchet Limit

2002 ◽  
Author(s):  
Nobuyoshi Yanagida ◽  
Masaaki Tanaka ◽  
Norimichi Yamashita ◽  
Yukinori Yamamoto
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Plastic Strain ◽  
Equivalent Stress ◽  
Equivalent Plastic Strain ◽  
Peak Stress ◽  
Element Analysis ◽  
Stress Evaluation ◽  
Elastic Plastic ◽  
Plastic Analysis

Alternative stress evaluation criteria suitable for Finite Element Analysis (FEA) proposed by Okamoto et al. [1],[2] have been studied by the Committee on Three Dimensional Finite Element Stress Evaluation (C-TDF) in Japan. Thermal stress ratchet criteria in plastic FEA are now under consideration. Two criteria are proposed: (1) Evaluating variations in plastic strain increments, and (2) Evaluating the width of the area in which Mises equivalent stress exceeds 3Sm. To verify of these criteria, we selected notched cylindrical vessel models as prime elements. To evaluate the effect of the local peak stress distribution on these criteria, cylindrical vessels with a semicircular notch on the outer surface were selected for this analysis. We used two notch configurations for our analysis, and the stress concentration factor for the notches was set to 1.5 and 2.0. We conducted elastic-plastic analysis to evaluate the ratchet limit. Sustained pressure and alternating enforced longitudinal displacements which causes secondary stress were used as parameters for the elastic-plastic analysis. We found that when no ratchet was observed, the equivalent plastic strain increments decreased and the area in which Mises equivalent stress exceeds 3Sm are below the certain range.

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