Development of an Automated Servo-Controlled Apparatus for Accurate Direct Shear Testing of Rock Joints under Different Boundary Conditions

Document Type : Technical Note

Authors

1 Dept. of Mining, Hamedan University of Technology, Iran

2 Dept. of Mining, Shahid Bahonar University of Kerman, Iran

Abstract

Summary
In this paper, an automated and servo-controlled apparatus is introduced which is capable of accurately conducting shear tests under different boundary conditions including constant normal load and constant normal stiffness.
 
Introduction
Precise and accurate measurement of shear strength of rock joints is of great importance in various projects related to rock engineering such as tunnels, dams, surface and underground mining, and oil shafts. In the laboratory, mechanical behavior of rock joints is studied by direct shear testing equipment. Manually controlled devices of direct shear testing are not adequately accurate. In this paper, development of an automated and servo-controlled device for direct shear testing of rock joints has been described.
 
Methodology and Approaches
The developed apparatus performs monotonic and cyclic shear tests with different rates. It also allows the correction of the involved area with shear displacement and adjusting the normal load accordingly. In addition to the possibility of terminating the experiment manually, conditions can be set in terms of the test duration, shear displacement, shear stress drop, or their combination to stop the experiment automatically. The data acquired by the displacement and load sensors are constantly transmitted to a personal computer connected to the device, and online graphs can be monitored during the experiment. Furthermore, some measures have been considered to remove sample clearance inside the shear box.
 
Results and Conclusions
Finally, the results of a number of direct shear tests carried out by the apparatus on the joints of known surface morphological characteristics are presented.

Keywords

Main Subjects

References

[1]           ASTM (2006) Standard Test Method for Performing Laboratory Direct Shear Strength Tests of Rock Specimens Under Constant Normal Force. In: Annual book of ASTM standards. pp 384–392
[2]           ISRM (2007) The complete ISRM suggested methods for rock characterization, testing and monitoring: 1974-2006. International Society for Rock Mechanics, Commission on Testing Methods
[3]           Hoek E (1970) Estimating the stability of excavated slopes in opencast mines. Transactions of the htstitution of Mhling and Metallurgy A109–A132.
[4]           Hoek E (1971) Influence of rock structure on the stability of rock slopes. In: Stability in Open Pit Mining, Proc. 1st International Conference on Stability in Open Pit Mining (Vancouver, November 23-25, 1970). pp 49–63
[5]           Ross-Brown DM, Walton G (1975) A portable shear box for testing rock joints. Rock mechanics 7:129–153.
[6]           Bandis SC, Lumsden AC, Barton NR (1983) Fundamentals of rock joint deformation. International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts 20:249–268. doi: http://dx.doi.org/10.1016/0148-9062(83)90595-8
[7]           Haberfield CM, Seidel JP (1998) Some recent advances in the modelling of soft joints in direct shear. In: Proc. Int. Conf. Geomechanics/Ground Control in Mining & Underground Construction. pp 71–84
[8]           Haque A, Indraratna B (2000) Shear behaviour of rock joints. CRC Press
[9]           Johnston IW, Lam TSK, Williams AF (1987) Constant normal stiffness direct shear testing for socketed pile design in weak rock. Geotechnique 37:83–89.
[10]         Indraratna B, Haque A, Aziz N (1998) Laboratory modelling of shear behaviour of soft joints under constant normal stiffness conditions. Geotechnical & Geological Engineering 16:17–44.
[11]         Jiang Y, Xiao J, Tanabashi Y, Mizokami T (2004) Development of an automated servo-controlled direct shear apparatus applying a constant normal stiffness condition. International Journal of Rock Mechanics and Mining Sciences 41:275–286.
[12]         Babanouri N, Karimi Nasab S, Baghbanan A, Mohamadi HR (2011) Over-consolidation effect on shear behavior of rock joints. International Journal of Rock Mechanics and Mining Sciences 48:1283–1291. doi: 10.1016/j.ijrmms.2011.09.010
[13]         Amiri Hossaini K, Babanouri N, Karimi Nasab S (2014) The influence of asperity deformability on the mechanical behavior of rock joints. International Journal of Rock Mechanics and Mining Sciences 70:154–161. doi: 10.1016/j.ijrmms.2014.04.009
Journal of Analytical and Numerical Methods in Mining Engineering
Volume 9, Issue 18
May 2019
Pages 143-152

Files

History

  • Receive Date: 07 May 2016
  • Revise Date: 06 August 2016
  • Accept Date: 10 December 2016

Share

How to cite

Statistics