The book Rock Engineering was published in June 2010. It is a must for those working in geo-planning of underground rock construction, as it presents the use of geological data from investigations through planning to construction. Correct use of rock engineering tools plays an important part in the book. More information can be found in Information

Uncertainties and tunnelling risks

The rockmasses surrounding an underground opening form a complex structure. Interpretations and extrapolations made to work out the geological setting, as well as extrapolation from the known conditions in the surface to the unknown along the tunnel, may introduce considerable uncertainties. Although extensive field investigation and good quality descriptions will enable the engineering geologist to predict the behaviour of a tunnel more accurately, it cannot remove the risk of encountering unexpected features.

Characterization and RockMass index (RMi)

In contrast to most other materials used for construction purposes, the quality of the rockmass is based on observations and evaluations rather than test results. This causes great challenges in the characterization of the parameters of the complex construction material called rockmass. Contrary to civil engineering and mining, the construction materials (rockmasses) in underground excavations are not characterized by their strength properties. As a consequence of this, the RockMass index (RMi) has been developed, with input of the geological parameters that have the greatest influence on rockmass strength.

Rock engineering and classification systems

An important requirement for all rock engineering is that the method or tool used, adequately covers the behaviour of the ground surrounding the tunnel or cavern. Frequently, rock engineering is based on observations, experience and personal judgement, where rockmass classification systems play an important role. How can such systems be applied correctly? What are the limitations?

Quotation

Important quotations will be presented here from time to time

Karl Terzaghi:
Even a very comprehensive and appropriately conducted geological survey of the site of a proposed tunnel cannot accomplish more than a very crude estimate of the length of the tunnel sections in which each of the principal types of rock conditions will be encountered. Further differentiation cannot be expected. Hence, even if methods for accurately computing the rock load under given rock conditions were available, they would have very little practical value on account of the inevitable uncertainties associated with predicting the rock conditions.