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IS 14210:1995 is the Indian Standard (BIS) for rock bolting for underground excavations. This code of practice provides guidelines for the design, installation, and testing of rock bolting systems for supporting underground excavations like tunnels, mines, and caverns. It covers rock mass classification using the RMR system, selection of appropriate bolt types, and quality control procedures to ensure rock stability.
Lays down procedures for design, installation, testing, and maintenance of rock bolts used for supporting underground excavations.
Overview
Status
Current
Usage level
Specialized
Domain
Geotechnical — Tunneling and Underground Structures
! The Rock Mass Rating (RMR) system detailed in Table 1 is fundamental to the entire design process in this code; accurate geological investigation is therefore paramount.
! Pull-out tests (Clause 8.2) are mandatory and should be performed on a specified percentage of production bolts (typically 1-2%) to verify design assumptions and installation quality.
! For grouted bolts, ensuring complete grout encapsulation without air voids is critical for corrosion protection and achieving the desired bond strength and long-term performance.
BS EN 1537:2013BSI - British Standards Institution, UK (European Standard)
HighCurrent
Execution of special geotechnical works - Ground anchors
Covers execution, testing, and monitoring of grouted anchors, highly analogous to grouted rock bolts.
ASTM F432-19ASTM International, USA
MediumCurrent
Standard Specification for Roof and Rock Bolts and Accessories
Focuses on the material specifications, manufacturing, and mechanical properties of the bolts themselves.
ITAtech Design Guidance for Rock-boltsITA-AITES - International Tunnelling and Underground Space Association, International
HighCurrent
ITAtech Design Guidance for Rock-bolts
Provides comprehensive, modern design guidelines specifically for rock bolt application in tunnelling.
ISO 18674-2:2016ISO - International Organization for Standardization, International
LowCurrent
Geotechnical investigation and testing — Geotechnical monitoring by field instrumentation — Part 2: Measurement of displacements along a line: Extensometers
Details the use of extensometers for monitoring, a key part of verifying rock bolt system performance.
Key Differences
≠IS 14210 is based on empirical methods and older rock mass classifications. Modern international standards (e.g., ITA Guidelines) place greater emphasis on numerical modelling and probabilistic design approaches.
≠International standards like BS EN 1537 specify more rigorous and categorized testing regimes (e.g., Investigation, Suitability, and Acceptance tests) with distinct procedures and criteria, whereas IS 14210 outlines a more general pull-out test procedure.
≠Material specifications in IS 14210 are broad, referencing general steel standards (like IS 2062). ASTM F432 provides much more detailed requirements for rock-bolt-specific steel grades, including heat treatment, chemistry, and specific mechanical properties.
≠IS 14210 provides limited guidance on corrosion protection. Modern international standards offer detailed options and specifications for various protection systems (e.g., double corrosion protection, galvanizing, epoxy coating) based on ground conditions and design life.
Key Similarities
≈All standards recognize the fundamental principle of rock reinforcement: to consolidate the rock mass, create a self-supporting arch, and control deformation.
≈Both IS 14210 and international counterparts universally require on-site pull-out testing to verify the load-bearing capacity of the installed bolts and validate design assumptions.
≈The basic classifications of rock bolts, such as mechanically anchored (point anchor) and fully grouted (resin or cement), are commonly recognized across all standards.
≈All relevant standards emphasize the critical importance of grout quality (strength, water-cement ratio, bleed) for ensuring effective load transfer from the steel tendon to the rock mass in grouted bolt systems.
Parameter Comparison
Parameter
IS Value
International
Source
Grout Compressive Strength (28-day)
Minimum 25 N/mm² (25 MPa)
Minimum 30 N/mm² (30 MPa) is common practice, specified in EN 447
BS EN 1537:2013
Grout Water/Cement Ratio (by mass)
Not to exceed 0.45
Maximum 0.45, often closer to 0.40 is recommended to limit bleed and increase durability
BS EN 1537:2013
Pull-out Test Load
Generally 1.5 times the design load
Proof load is typically 1.25 times the characteristic resistance (design load)
BS EN 1537:2013
Grout Bleed Limit
Max 2% after 2 hours, 4% total
Max 2% after 3 hours at 20°C, 4% total (as per EN 445 test method)
BS EN 1537:2013
Typical Bolt Steel Yield Strength
250 MPa (for steel grade IS 2062 E250)
379 MPa (for Grade 55) to 517 MPa (for Grade 75)
ASTM F432-19
Pull-out Test Creep Acceptance
Residual load after 24 hours should not be less than 95% of design load.
Creep displacement (log time) should not exceed 1mm to 2mm between specific time intervals (e.g., 1 min to 10 min).
BS EN 1537:2013
⚠ Verify details from original standards before use
Key Values6
Quick Reference Values
RMR range for 'Good' Rock61 to 80
RMR range for 'Very Poor' Rock< 20
Typical grout water-cement ratio0.4 to 0.5
Minimum 28-day grout compressive strength25 MPa
Pull-out test load requirement1.5 times the design load
Torque for 20mm mechanically anchored bolt200-250 Nm
Key Formulas
L = 2 + 0.15B — Bolt length (L) for large cavern with span (B) > 20 m (Clause 7.3)
L = B/2 to B/3 — Rule of thumb for bolt length (L) based on excavation span (B)
Tables & Referenced Sections
Key Tables
Table 1 - Rock Mass Classification (Based on RMR System)
Table 2 - Guidelines for Support Pressure
Table 3 - Guidelines for Bolt Spacing and Rock Load
How is the required rock support determined using this code?+
The support is determined based on the Rock Mass Rating (RMR) calculated as per Clause 4 and Table 1. This classification then guides the required support pressure, bolt length, and spacing using Tables 2 and 3.
What is the purpose of a pull-out test on a rock bolt?+
A pull-out test (Clause 8.2.2) is performed to verify the load-carrying capacity of the installed rock bolt, confirming that the anchorage is effective and meets the specified design load.
What are the common types of rock bolts mentioned?+
The code covers various types (Clause 6), including mechanically anchored bolts, grouted dowels (rebar), and resin-grouted bolts, each suitable for different rock conditions and support requirements.
How long should a rock bolt be?+
As a rule of thumb, bolt length is typically 1/3 to 1/2 of the excavation span. Clause 7.3 provides more specific guidance for different conditions.