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IS 6922:1973 is the Indian Standard (BIS) for criteria for safety and design of structures subject to underground blasts. This standard provides criteria for the safety and design of structures subjected to ground vibrations from underground blasts. It establishes damage thresholds based on Peak Particle Velocity (PPV) for different types of structures and outlines methods to predict vibration levels from blasting operations.
Criteria for safety and design of structures subject to underground blasts
! The core of this standard is controlling Peak Particle Velocity (PPV) at the structure's foundation. The permissible PPV depends heavily on the structure's type, age, and condition as per Table 1.
! The vibration propagation formula is empirical. Site-specific constants (K, B) must be determined through trial blasts and measurements for reliable predictions.
! The damage criteria in Table 1 assume short-term blast vibrations. For continuous or long-duration vibrations, lower limits should be considered.
Structure Response and Damage Produced by Ground Vibration from Surface Mine Blasting
Provides the seminal frequency-dependent criteria for ground vibration limits (PPV) to prevent damage to low-rise structures.
DIN 4150-3:2016-12Deutsches Institut für Normung (DIN), Germany
HighCurrent
Vibration in buildings - Part 3: Effects on structures
Specifies methods for evaluating the effects of vibration on structures and defines guideline values for various building types.
BS 7385-2:1993British Standards Institution (BSI), UK
HighCurrent
Evaluation and measurement for vibration in buildings. Guide to damage levels from groundborne vibration
Gives guidance on damage levels from groundborne vibration and provides frequency-dependent limits for various structure types.
AS 2187.2-2006Standards Australia, Australia
MediumCurrent
Explosives - Storage and use - Part 2: Use of explosives
A comprehensive standard on explosives use that includes specific criteria for controlling ground vibration and airblast.
Key Differences
≠IS 6922:1973 provides Peak Particle Velocity (PPV) limits that are largely independent of the vibration's frequency. Modern standards like USBM RI 8507 and DIN 4150-3 use frequency-dependent PPV limits, which are more stringent at low frequencies (below 10-15 Hz) and more permissive at higher frequencies.
≠The Indian standard does not provide specific quantitative limits for airblast overpressure, focusing solely on ground vibration. In contrast, standards like AS 2187.2 provide explicit decibel (dBL) limits for airblast to prevent window damage and public annoyance.
≠IS 6922 is based on research and data from before 1973. International standards have been updated with data from extensive studies using modern instrumentation, leading to more refined damage criteria and prediction models.
≠The classification of structures in IS 6922 is quite general (e.g., 'Houses', 'Industrial buildings'). DIN 4150-3 offers a more detailed classification system (e.g., 'Buildings used for commercial purposes', 'Dwellings', 'Buildings sensitive to vibration') which allows for more tailored limit values.
Key Similarities
≈All standards universally adopt Peak Particle Velocity (PPV) as the primary indicator for assessing the potential for ground vibration to cause structural damage.
≈The concept of 'scaled distance' (a function of the distance from the blast and the explosive charge weight) is a fundamental tool used in all standards for predicting vibration levels and planning blasts.
≈The fundamental objective across IS 6922 and its international counterparts is the same: to provide a scientific and engineering basis for conducting blasting operations safely, without causing damage to nearby structures.
≈All standards differentiate between types of structures, applying more conservative (lower) vibration limits to sensitive or historically important buildings compared to standard residential or industrial structures.
Parameter Comparison
Parameter
IS Value
International
Source
PPV Limit for Residential Structures
5-12 mm/s, depending on building type and foundation. It is not frequency-dependent.
Varies with frequency, e.g., 5 mm/s below 10 Hz, ramping up to 20 mm/s between 10-50 Hz.
DIN 4150-3
Frequency Dependency of Limits
Not explicitly defined; provides fixed PPV values.
Explicitly defined; a graphical chart or tiered system where allowable PPV increases with frequency.
Often uses or refers to cube root scaling (Charge Weight^0.33) as a common alternative, while emphasizing site-specific regression analysis.
General practice, e.g., AS 2187.2
Airblast Overpressure Limit
Not specified.
115 dBL (general recommended limit for sensitive areas).
AS 2187.2-2006
Damage Threshold for Cosmetic Cracks
Implicit in the PPV limits (e.g., exceeding 8-12 mm/s for houses may cause damage).
Guide value is 15 mm/s at 4 Hz, increasing to 50 mm/s at 40 Hz and above for intermittent vibration.
BS 7385-2
⚠ Verify details from original standards before use
Key Values5
Quick Reference Values
PPV for no damage (well-designed structures)25 mm/s
PPV for minor damage threshold (residential)10 - 12.5 mm/s
PPV for severe damage threshold (residential)20 - 25 mm/s
PPV for safe limit (sensitive heritage structures)2.0 - 2.5 mm/s
General safe limit adopted for residential buildings5 mm/s
Key Formulas
v = K * (R / Q^0.5)^-B — Ground vibration propagation formula, where v is PPV, R is distance, Q is charge weight, and K and B are site constants.
Tables & Referenced Sections
Key Tables
Table 1 - Damage Criteria for Various Types of Structures due to Short-Term Blasting Vibrations
Key Clauses
Clause 3 - Notations and Definitions
Clause 4 - Damage Criteria
Clause 5 - Procedure for forecasting damage
Appendix A - Propagation of Ground Motion
Frequently Asked Questions3
What is the safe vibration limit for a typical residential house?+
A PPV of 5 mm/s is a commonly adopted safe limit to avoid even minor cosmetic cracks. The threshold for minor cracking is 10-12.5 mm/s according to Table 1.
How is vibration intensity measured for this code?+
Vibration intensity is measured as Peak Particle Velocity (PPV) in mm/s, using a seismograph placed on the ground near the structure's foundation. (Clause 3.2)
What is 'scaled distance' in blasting?+
Scaled distance is a term that combines distance (R) and explosive charge weight (Q) into a single parameter, typically R/√Q. It is used in the propagation formula to predict PPV. (Appendix A)