scholarly journals Analytical Solution for the Deformation and Support Parameters of Coal Roadway in Layered Roof Strata

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Kai Wang ◽  
Bao-gui Yang ◽  
Zhong-kui Wang ◽  
Xiao-long Wang
Keyword(s):  
High Efficiency ◽  
Design Method ◽  
Beam Theory ◽  
High Strength ◽  
Failure Criteria ◽  
Key Stratum ◽  
Coal Roadway ◽  
The Stability ◽  
Roof Strata

In order to meet the security and high-efficiency production needs, high-strength bolt (cable) reinforcement technology is usually used to maintain the stability of roadways. However, due to the great variability of lithology and mechanical properties, the failure form and stability of the layered roof in coal roadways are significant differences. The traditional supporting design method of the layered roof support in coal roadways is the engineering analogy method, which depends on experiences rather than theoretical analysis. Based on the theory of the elastic foundation beam and key stratum, this paper establishes a simplified analytical model of layered roof strata in coal roadways. Based on the Mohr-Coulomb theory, this paper gives the failure criteria of the layered roof strata, and the failure range of the layered roof strata is obtained. The length and pretightening force of bolt (cables) of the layered roof strata can be calculated based on the suspension theory and composite beam theory, which providing a quantitative theoretical basis for the determination of supporting parameters. Finally, as a case, the layered roof strata failure range and supporting parameters of the S1301 auxiliary transportation roadway in Gucheng coal mine are calculated.

Study and Application of Three-Step Supporting Design Method in Coal Roadway

2013 ◽  
Vol 353-356 ◽  
pp. 252-257
Author(s):  
Ren Liang Shan ◽  
Xiang Song Kong ◽  
Ji Jun Zhou ◽  
Wen Feng Zhao ◽  
Yu Tao ◽  
...  
Keyword(s):  
Design Method ◽  
Surrounding Rock ◽  
Second Step ◽  
Preliminary Design ◽  
The Third ◽  
Coal Roadway ◽  
Roadway Stability ◽  
Simulation Calculation ◽  
Roadway Support ◽  
The Stability

Scientific supporting design is of great significance to ensure coal roadway stability. The three-step supporting design method is put forward for coal roadway support: The first step is preliminary design, determine the range of each supporting parameter according to the theoretical calculation and supporting experiences; the second step is numerical simulation calculation, choose the reasonable one through the comparison of schemes; the third step is field monitoring, verify the scheme applicability. After applying the three-step supporting design method to study 3# coal seam roadway in Guandi mine, the optimal supporting scheme is obtained, and good results of underground roadway are achieved, which ensure the stability of roadway surrounding rock. Meanwhile, some rules are summarized which provide references for future roadway supporting design.

Buckling and Post-Buckling Behavior for Roof Strata in Longwall Mining

2012 ◽  
Vol 170-173 ◽  
pp. 751-754
Author(s):  
Qun Song ◽  
Zhi Lin Yang
Keyword(s):  
Longwall Mining ◽  
Main Roof ◽  
Equilibrium Path ◽  
Fracture Characteristics ◽  
Key Stratum ◽  
Buckling Behavior ◽  
Roof Stratum ◽  
Post Buckling ◽  
The Stability ◽  
Roof Strata

In accordance with the occurrence behavior of roof strata and the fracture characteristics of key stratum in shallow seam longwall mining, this paper studied the post-buckling behaviors of key roof stratum in the process of mining by using initial post-buckling theory, which derived a critical load and a breaking span of the main roof during the first weighting, determined the final subsidence for broken key stratum, and presented an application with the example of Daliuta 1203 face. The results indicate that the rock blocks a in are state of non-equilibrium after main roof breaking, the equilibrium path of main roof is unstable from breaking to final subsidence; thick unconsolidated layers above roof have effect on post-buckling behaviors of key stratum; the stability for bifurcation point equilibrium configuration and post-buckling equilibrium path of roof strata could be revealed and an effective method for determining displacement field of imperfection structure could be provided by using initial post -buckling theory.

scholarly journals Moving Least Squares Method for a One-Dimensional Parabolic Inverse Problem

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Baiyu Wang
Keyword(s):  
Inverse Problem ◽  
Least Squares ◽  
High Efficiency ◽  
Least Squares Method ◽  
Parabolic Problems ◽  
Moving Least Squares ◽  
One Dimensional ◽  
Moving Least Squares Method ◽  
The Stability

This paper investigates the numerical solution of a class of one-dimensional inverse parabolic problems using the moving least squares approximation; the inverse problem is the determination of an unknown source term depending on time. The collocation method is used for solving the equation; some numerical experiments are presented and discussed to illustrate the stability and high efficiency of the method.

Investigation on Joining Method Replacement for Vehicle Body’s Assembly

2011 ◽  
Vol 189-193 ◽  
pp. 3621-3624
Author(s):  
Jian Lin ◽  
Yi Zhong ◽  
Yong Ping Lei
Keyword(s):  
Shear Failure ◽  
Design Method ◽  
Laser Beam Welding ◽  
Dissimilar Materials ◽  
High Strength ◽  
Failure Criteria ◽  
Vehicle Body ◽  
Welding Arc ◽  
Bonded Joint ◽  
Equivalent Strength

Various joining methods (i.e., spot welding, arc welding, laser beam welding) have been used for vehicle body assembly. However it is unclear for the equivalent conversion of various joints which has the equivalent joint strength for the vehicle body, such as weld-bonded joint, SPR joint, which have been considered likely to replace RSW in the area of high strength steel’s joining. In order for the flexible design in the auto line of vehicles body’s joining, the equivalent (strength) weld pitch design method for various joints, including the joining of similar and dissimilar materials, is presented in this work. And some primary simulating results are presented and discussed. It is shown that the conversion method for various joints can be established based on the joint’s shear failure criteria. And the conversion results can be influenced by the sheet gage obviously. The failure criteria of various joint still need further investigation based on the simulating and experimental results.

An Analytical Design Method for Milling Cutters With Nonconstant Pitch to Increase Stability, Part I: Theory

2003 ◽  
Vol 125 (1) ◽  
pp. 29-34 ◽  
Author(s):  
E. Budak
Keyword(s):  
Surface Finish ◽  
Design Method ◽  
Stability Limit ◽  
Analytical Stability ◽  
Chatter Vibrations ◽  
Improved Stability ◽  
Limited Frequency ◽  
The Stability ◽  
Explicit Relation

Chatter vibrations result in reduced productivity, poor surface finish and decreased cutting tool life. Milling cutters with nonconstant pitch angles can be very effective in improving stability against chatter. In this paper, an analytical stability model and a design method are presented for nonconstant pitch cutters. An explicit relation is obtained between the stability limit and the pitch variation which leads to a simple equation for determination of optimal pitch angles. A certain pitch variation is effective for limited frequency and speed ranges which are also predicted by the model. The improved stability, productivity and surface finish are demonstrated by several examples in the second part of the paper.

Based on Mathematical Simulation of the Supporting Design Method in Gateway

2012 ◽  
Vol 616-618 ◽  
pp. 301-305
Author(s):  
Cheng Wen Zhang ◽  
Wan Bin Yang ◽  
Hui Dong
Keyword(s):  
Objective Function ◽  
Mathematical Simulation ◽  
Design Parameter ◽  
Design Method ◽  
Failure Zone ◽  
Coal Roadway ◽  
Natural Factors ◽  
Roadway Stability ◽  
Geological Conditions ◽  
The Stability

The stability of roadway is subject to a variety of conditions, including geological conditions, and other natural factors can not be changed, it must be through supporting the roadway stability. At present the design of supporting parameters in the gateway have many methods, but there are some shortcomings. This paper used non-linear FEM to optimize the supporting parameters. The coal roadway minimum failure zone within surround rock has been set as objective function. The results show that: The support parameters and the failure zone within surround rock exist optimal relations, which can be used as a method of supporting design parameter.

scholarly journals An accurate method for the calculation of ultimate load in lattice boom

2019 ◽  
Vol 11 (11) ◽  
pp. 168781401988677 ◽  
Author(s):  
Liming Zhou ◽  
Jinghao Tang ◽  
Weijie Wang ◽  
Erfei Zhao ◽  
Shuhui Ren ◽  
...  
Keyword(s):  
High Strength Steel ◽  
Ultimate Load ◽  
Design Method ◽  
High Strength ◽  
Accurate Method ◽  
Effective Length ◽  
Stability Factor ◽  
Steel Tubes ◽  
Effective Length Factor ◽  
The Stability

To calculate the ultimate load of the lattice boom accurately, the effective length factor and imperfection factor are introduced to the current stability factor formula. First, we propose a stability factor formula by conducting a series of tests of high-strength steel tubes under axial compression and analyzing the experimental data. Second, the effective length factor of the chord which is caused by braces is calculated on the basis of different effective length factors and stability curves. Then, the correctness of the proposed effective length factor and the stability factor formula are proved by destructive tests under three loading modes. Using the modified stability factor formula, the accuracy of ultimate load of lattice boom is enhanced. These findings will be of great value for improving the design level of lattice boom and providing a theory and test basis for the completion of the buckling design method of the high-strength steel tubes.

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