Analysis of un-tensioned fully grouted rock bolt – A case study

DOI

10.2991/rare-16.2016.18How to use a DOI?

Keywords

Rock bolt; pull-out test; anchorage strength; numerical modelling; underground excavation; metal mining

Abstract

Stability of structures in any mining excavation is critical and roof rock stability has long been the primary concern in all underground excavations. There are plenty of supports systems that has evolved over the years, among them rock bolts are widely used support system in mining and various civil engineering operations. The bolts reinforce the loose and weak strata to make it, self-supportive by enhancing the inherent strength. Anchoring of the rock bolt plays an important role when deformation or movement of the layers in the rock mass induce axial tensile load in the installed rock bolts. Bolts will fail if the applied or induced axial load to the bolt is more than the anchorage strength. Anchorage strength depends on many factors such as type of bolt, annular space, grouting media, shear behavior at the bolt-grout interface, surface profile, installation mechanism and position. The paper presents performance of fully grouted un-tensioned rebar bolts in an Indian underground metal mine having competent host rock. The bolts were installed using cement (water to cement ratio 0.36) as grouting material. The embedded anchorage length was varied and a series of 30 bolts were tested to determine the anchorage strength in field conditions by conducting pull-out test at different duration from the time of installation of the bolts. Simulation studies were done using a finite difference method to analyze the redistribution of mining induced stresses due to excavation at depth of 150 m for the surface. The load-displacement curves were developed for the bolts subjected to in-situ pull-out test and the safety factor was analyzed for the strata when unsupported using fast lagrangian analysis of continua codes. The results indicates the successful application of un-tensioned fully grouted bolts in supporting the underground excavation. The axial deformation curve of bolts indicate the de-bonding nature along the bolt

Copyright

© 2016, the Authors. Published by Atlantis Press.

Open Access

This is an open access article distributed under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/).

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TY  - CONF
AU  - Singh Deepanshu R
AU  - Mishra Arvind K
AU  - Agrawal Harshit
AU  - Manna Chanchal
PY  - 2016/11
DA  - 2016/11
TI  - Analysis of un-tensioned fully grouted rock bolt – A case study
BT  - Proceedings of the conference on Recent Advances in Rock Engineering (RARE 2016)
PB  - Atlantis Press
SP  - 110
EP  - 117
SN  - 2352-5401
UR  - https://doi.org/10.2991/rare-16.2016.18
DO  - 10.2991/rare-16.2016.18
ID  - DeepanshuR2016/11
ER  -