The Geological Strength Index (GSI) system, proposed in 1994 by

Evert Hoek Evert Hoek FREng (born in 1933 in Southern Rhodesia, now Zimbabwe) is a Zimbabwean-Canadian Mechanical Engineer specialized Geotechnical Engineering and a leading international expert in rock mechanics. Hoek began his research for Rock Mechanics i ...

, is used for the estimation of the rock mass strength and the rock mass deformation modulus. The GSI system concentrates on the description of two factors, rock structure and block surface conditions. The guidelines given by the GSI system are for the estimation of the peak strength parameters of jointed rock masses. There are no guidelines given by the GSI, or by any other system, for the estimation of the rock mass’ residual strength that yield consistent results. Another method is that defined in the work of Cole & Stroud whereby the basic strength, in

Newtons The newton (symbol: N) is the unit of force in the International System of Units (SI). It is defined as 1 kg⋅m/s, the force which gives a mass of 1 kilogram an acceleration of 1 metre per second per second. It is named after Isaac Newton in r ...

, and the shear strength in Kg/cm2, can be estimated empirically by varied responses to hammer, knife & finger nail.https://gndec.ac.in/~igs/ldh/conf/2009/articles/T11_08.pdf

References

Hoek, E. (1994) "Strengths of rock and rock masses" ISRM News Journal, 2(2): 4–16.

References

Further reading