Engineering Properties of Rocks
Preface
For different reasons, it is often difficult for rock engineers to directly obtain the specific design parameter(s) of interest. As an alternative, they use the typical values or empirical correlations of similar rocks to estimate the specific parameter(s) of interest indirectly. For example, the unconfined compressive strength (UCS) of intact rock is widely used in designing surface and underground structures. The procedure for measuring UCS has been standardized by both the American Society for Testing and Materials (ASTM) and the International Society for Rock Mechanics (ISRM). Although the method is relatively simple, it is time consuming and expensive; also, it requires well-prepared rock cores, which is often difficult or even impossible for weak rocks.
Therefore, indirect tests are often conducted to estimate the UCS by using empirical correlations, such as point load, Schmidt hammer, sound velocity and impact strength tests. Another example is the determination of the deformation modulus of rock masses. Rock masses usually contain discontinuities. To obtain realistic values of rock mass deformation modulus, in situ tests, such as plate bearing, flat jack, pressure chamber, borehole jacking and dilatometer tests, need be conducted. The in situ tests, however, are time-consuming, expensive and, in some cases, even impossible to carry out. Therefore, the deformation modulus of rock masses is often estimated indirectly from correlations with classification indices such as RQD (Rock Quality Designation), RMR (Rock Mass Rating), Q (Q-System) and GSI (Geological Strength Index).
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Preface
For different reasons, it is often difficult for rock engineers to directly obtain the specific design parameter(s) of interest. As an alternative, they use the typical values or empirical correlations of similar rocks to estimate the specific parameter(s) of interest indirectly. For example, the unconfined compressive strength (UCS) of intact rock is widely used in designing surface and underground structures. The procedure for measuring UCS has been standardized by both the American Society for Testing and Materials (ASTM) and the International Society for Rock Mechanics (ISRM). Although the method is relatively simple, it is time consuming and expensive; also, it requires well-prepared rock cores, which is often difficult or even impossible for weak rocks.
Therefore, indirect tests are often conducted to estimate the UCS by using empirical correlations, such as point load, Schmidt hammer, sound velocity and impact strength tests. Another example is the determination of the deformation modulus of rock masses. Rock masses usually contain discontinuities. To obtain realistic values of rock mass deformation modulus, in situ tests, such as plate bearing, flat jack, pressure chamber, borehole jacking and dilatometer tests, need be conducted. The in situ tests, however, are time-consuming, expensive and, in some cases, even impossible to carry out. Therefore, the deformation modulus of rock masses is often estimated indirectly from correlations with classification indices such as RQD (Rock Quality Designation), RMR (Rock Mass Rating), Q (Q-System) and GSI (Geological Strength Index).
Download
http://s18.alxa.net/s18/srvs2/01/Eng...s.of.Rocks.rar