IS 13063:1991 is the Indian Standard (BIS) for the structural safety of buildings on shallow foundations on rocks. This code provides guidelines for ensuring the structural safety of buildings founded on shallow foundations resting on rock. It covers site investigation, determination of rock properties, and methods for calculating bearing capacity and permissible settlement. The code addresses both intact and jointed rock masses, offering presumptive values and analytical methods for foundation design.
Code of practice for the structural safety of buildings on shallow foundations on rocks
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Design Philosophy | Working Stress Method (WSM) with a global factor of safety. | Limit State Design (LSD) with partial factors of safety. | EN 1997-1:2004 |
| Factor of Safety on Bearing Capacity | A minimum global Factor of Safety of 3.0 is recommended. | A partial factor on bearing resistance (γR) of 1.4 is applied for Ultimate Limit State (ULS) in Design Approach 1, Combination 2. | EN 1997-1:2004 |
| Presumptive Bearing Value (Hard, sound rock) | 3.2 MPa (3300 kN/m²) for 'Hard rock without lamination and defects' (as per referenced National Building Code of India). | 0.57 MPa (12,000 psf) for 'Crystalline bedrock'. The US code values are typically more conservative. | IBC 2021 |
| Permissible Total Settlement (on Rock) | 12 mm for both isolated footings and rafts (as per referenced IS 1904). | Typically limited to 25 mm (1 inch), but must be determined based on the structure's tolerance to movement as a Serviceability Limit State. | Canadian Foundation Engineering Manual |
| Rock Classification (High Strength) | High Strength Rock: Uniaxial Compressive Strength (UCS) of 100-200 MPa (as per related Indian standards like IS 12070). | Very Strong Rock: UCS of 100-250 MPa. | EN ISO 14689-1:2018 |
| Consideration of Rock Quality Designation (RQD) | Recommended as a measure of rock mass quality. RQD > 75% indicates good quality rock. | Used widely as a key input parameter for rock mass classification systems (e.g., RMR, Q-system) which are then used to estimate strength and modulus. | General practice in Eurocode 7 / CFEM |