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IS 13365:2000 (Part 1) is the Indian Standard (BIS) for the quantitative classification system of rock mass - guidelines, part 1: rmr for predicting engineering properties. This guideline establishes the Rock Mass Rating (RMR) system, a standardized method for classifying rock masses. It details the process of assigning a numerical rating based on five key parameters: rock strength, RQD, discontinuity spacing, discontinuity condition, and groundwater. The final RMR value helps in determining rock mass quality, predicting its engineering behavior, and providing initial guidelines for excavation and support systems in tunnels and other structures.
The quantitative classification system of rock mass - Guidelines, Part 1: RMR for predicting engineering properties
Standard Guide for Using Rock Mass Classification Systems for Engineering Purposes
Provides guidelines for using the RMR system (Bieniawski, 1989), which is the basis for IS 13365.
BS 5930:2015+A1:2020BSI (British Standards Institution), UK
MediumCurrent
Code of practice for ground investigations
Describes and recommends the use of rock mass classification systems, including RMR, for rock description and characterization.
EN 1997-1:2004CEN (European Committee for Standardization), Europe
LowCurrent
Eurocode 7: Geotechnical design - Part 1: General rules
A design standard that allows the use of classification systems like RMR for determining geotechnical parameters and ground models.
Key Differences
≠IS 13365:2000 is a prescriptive standard codifying the RMR 1989 version, whereas ASTM D5878 is a 'Standard Guide' offering informative guidance on using RMR and other systems like the Q-system, providing a broader context.
≠ASTM D5878 discusses later developments, such as RMR14, which introduces a new 'Excavation Disturbance Factor (Fd)'. IS 13365:2000, being an older document, is strictly based on the 1989 version (RMR89) and does not include these updates.
≠IS 13365 is a standalone document focused solely on the RMR system. In contrast, ASTM D5878 and BS 5930 are part of a larger framework of standards, extensively cross-referencing other specific standards for determining input parameters (e.g., ASTM D7012 for UCS).
Key Similarities
≈Both standards use the same five fundamental input parameters to calculate the basic RMR: Intact Rock Strength, RQD, Discontinuity Spacing, Discontinuity Condition, and Groundwater Conditions.
≈The rating scales and numerical values assigned to different levels within each of the five input parameters are identical, as both standards are derived from Bieniawski's 1989 classification system.
≈Both systems use a subsequent, identical subtractive adjustment to the basic RMR score to account for the influence of discontinuity orientation relative to the engineering excavation (e.g., 'very unfavourable' for tunnels is -12).
≈The final rock mass classes (Class I to V, from 'Very Good Rock' to 'Very Poor Rock') are defined by the same RMR score ranges (e.g., Class II is RMR 61-80) in both standards.
Parameter Comparison
Parameter
IS Value
International
Source
Rating for Intact Rock Strength (UCS > 250 MPa)
15
15
ASTM D5878-19 (via Bieniawski 1989)
Rating for RQD (90-100%)
20
20
ASTM D5878-19 (via Bieniawski 1989)
Rating for Discontinuity Spacing (>2m)
20
20
ASTM D5878-19 (via Bieniawski 1989)
Rating for Discontinuity Condition (Very rough, non-softening, tight)
30
30
ASTM D5878-19 (via Bieniawski 1989)
Rating for Groundwater (Completely Dry)
15
15
ASTM D5878-19 (via Bieniawski 1989)
Boundary between 'Good Rock' (Class II) and 'Fair Rock' (Class III)
RMR = 60
RMR = 60
ASTM D5878-19 (via Bieniawski 1989)
Predicted Cohesion for RMR 61-80 ('Good Rock')
300 - 400 kPa
300 - 400 kPa
ASTM D5878-19 (via Bieniawski 1989)
⚠ Verify details from original standards before use
Table 1 - Adjustment Rating for Joints (F1, F2, F3)
Table 2 - Adjustment Rating for Method of Excavation (F4)
Table 3 - Rock Mass Classes Based on SMR
Table 4 - Meaning of Rock Mass Classes
Key Clauses
Clause 4 - Method of Determination of Slope Mass Rating (SMR)
Clause 4.3 - Adjustment Rating for Joints (F1, F2, F3)
Clause 4.4 - Adjustment Rating for Method of Excavation (F4)
Clause 5 - Description of Rock Mass Classes based on SMR
Frequently Asked Questions4
What is the primary formula for SMR?+
SMR = RMR_basic + (F1 × F2 × F3) + F4, where RMR_basic is from IS 13365 (Part 1). (Clause 4.1)
How are the adjustment factors F1, F2, and F3 determined?+
They depend on the geometric relationship between the strike and dip of discontinuities and the slope face, as detailed in Table 1.
What does the F4 factor represent?+
F4 is an adjustment for the method of excavation, accounting for disturbance. It ranges from +15 for a natural slope to -8 for poor blasting. (Table 2)
What is a 'Fair' slope according to SMR?+
A slope with an SMR value between 41 and 60 is classified as 'Fair' (Class III), indicating it is partially stable. (Table 3)