What is the basis for this classification system?

The code is based on the classical rock load classification system proposed by Karl von Terzaghi for estimating loads on tunnel supports.

What is 'Squeezing Rock' according to this code?

It's rock that slowly advances into an excavation, like a tunnel, without a perceptible increase in volume. The code distinguishes between moderate depth (Class VI) and great depth (Class VII).

Is this code used for designing rock slopes?

It can be used for a preliminary qualitative assessment of the rock mass forming the slope, but specific slope stability analysis methods are required for design.

Does this standard replace newer methods like RMR?

No, it has not been formally replaced. However, in practice, RMR (IS 13365) and the Q-system are more commonly used for detailed engineering design due to their quantitative nature.

IS 10042

: 1981

Code of practice for rock mass classification for civil engineering works

CurrentSpecializedCode of PracticeGeotechnical · Surveying and Geotechnical Investigation

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This code provides a standardized method for classifying rock masses for civil engineering projects, particularly for assessing conditions in tunnels and underground excavations. The classification is based on Terzaghi's classic rock load theory, categorizing rock based on its structural features, such as jointing and behavior under load (e.g., squeezing or swelling).

Provides systems and guidelines for classification of rock masses based on engineering properties for civil engineering applications.

Quick Reference Values

Class IHard and intact rock

Class IIHard stratified or schistose rock

Class IIIMassive, moderately jointed rock

Class IVModerately blocky and seamy rock

Class VCrushed but chemically intact rock

Class VISqueezing rock, moderate depth

Class VIISqueezing rock, great depth

Class VIIISwelling rock

Practical Notes

This code is based on Terzaghi's classification system, which is foundational but largely qualitative and developed for steel-supported tunnels. It requires considerable geological experience to apply correctly.

For modern quantitative design, this system is often supplemented or superseded by the Rock Mass Rating (RMR) system (IS 13365 Part 1) or the Tunnelling Quality Index (Q-system).

The classification provides a framework for preliminary assessment and communication but does not yield direct engineering parameters for design.