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A New Experimental System for Quantifying the Multidimensional Loads on an on-Site Hydraulic Support in Steeply Dipping Seam Mining

  • Y. P. Wu
  • B. S. HuEmail author
  • P. S. Xie
Applications Paper
  • 55 Downloads

Abstract

Model supports are widely used for selecting the type of field support and quantifying the working resistance in coal seam mining. These devices may also be employed for reproducing phenomena induced by human activities, such as advancement of the working face, in three-dimensional physical model experiments. This study investigates the relevance of the currently used model supports and finds that the interactions between the model supports and surrounding rocks are unavoidable; the three-dimensional load characteristics of the model support is also immeasurable. Therefore, first, we design a type of hydraulic-powered model support via a real case study. For this, a series of theoretical analyses is performed and the design criteria are proposed. Second, the model support and an integrated measurement system are developed and compared with previous model supports. The newly developed system has the following advantages: i) adopts a hydraulic loading-control system and hydraulic oil for power; ii) equipped with high-precision displacement-measuring elements and pressure-measuring elements for determining the three-dimensional loads of the support (quantitative values for the model support include the working resistance, lateral pushing force transferred from the adjacent supports, and thrust force from the caving-gangue). Subsequently, the performance of the integrated system is tested, following which the integrated system is used in a three-dimensional physical model experiment of working face 3232 of the Lvshuidong coal mine. It is noteworthy that the integrated system can contribute in obtaining the missing load information and increase the quality of the parameters measured in steeply dipping seam mining.

Keywords

Steeply dipping coal seams Hydraulic-powered model support Support–surrounding rock interactions Working resistance Three-dimensional physical model experiment 

Abbreviations

i

Number of (model) support at working face

m

Total number of (model) support

Fmi

Working resistance of the ith model support in the physical model experiment, kN;

Ji

Lateral pushing resultant of the ith model support, kN

Ti

Thrust force of the ith model support from the caving-gangue, kN

Jsi

Lateral pushing force of the ith model support transferred from the upper support, kN

Jxi

Lateral pushing force of the ith model support transferred from the lower support, kN

Cl

Constant of geometric similarity

Fi

Working resistance of the ith on-site hydraulic-powered support, kN

ks

Stiffness of the model support, N/mm

Fie

Supporting resistance of the ith model support at the end of the resistance increasing phase, kN

Fib

Supporting resistance of the ith model support at the initial supporting phase, kN

W

Weight of the support, kN

R

Force floor to the support, kN

B

Support width, m

h

Support height,m

Tx

Component of T along the direction of the working face width, kN

Ty

Component of T along the direction of the pseudo-inclined working face length, kN

Fid

Inherent toppling force of the support, kN

μ1

Frictional coefficient between the support and roof

μ2

Frictional coefficient between the support and floor

μ3

Frictional coefficient between the support and caving-gangue

α

Dip angle of the steeply dipping coal seam, (°)

β

Pseudo dip angle of the steeply dipping working face, (°)

θ

The toppling angle of support caused by relative movement of roof and floor strata, (°)

b

Distance from Fi to the front of the base, m

c

Distance from W to the front of the base, m

αh

Critical sliding angle of the model support, (°)

n

Ratio of the outspread length of broken rock along the pseudo-inclined working face direction to the width of a single support, is dimensionless

γ

Mean density of the overlying strata, Kg/m3

H

Cover depth of the steeply dipping coal seam, m

[Pi]

Actual working resistance of the model support, kN

Pi

Working resistance of the model support, maintaining dynamic stabilization, kN

Pj

Working resistance of the model support when the working face advances, kN

Pj*

Working resistance of the model support when the working face advances and also maintains its dynamic stabilization, kN

ƩHc

Thickness of the main roof, m

ƩHb

Thickness of the immediate roof, m

p1

Pressure of the hydraulic loading system at the outlet end, MPa

d

Diameter of a prop, mm

Notes

Acknowledgements

This work was financially supported by the Key Program of National Natural Science Foundation of China (Grand No.51634007) and The National Natural Science Foundation of China (Grand No. 51774230). The corresponding author would like to thank the Research Team on Safe and Efficient Mining of Coal Seams with Complex Mining Conditions at Xi’an University of Science and Technology for its financial support provided for his Ph.D. study at TU Bergakademie Freiberg, Germany.

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Copyright information

© The Society for Experimental Mechanics, Inc 2019

Authors and Affiliations

  1. 1.School of Energy and Mining EngineeringXi’an University of Science and TechnologyXi’anChina
  2. 2.Key Laboratory of Western Mine Exploitation and Hazard PreventionMinistry of EducationXi’anChina

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