Predicting the Schmidt hammer values of in-situ intact rock from core sample values

摘要

It was known that there are strong correlations between Schmidt hammer value and cutting rate of roadheaders and TBMs. But, these Schmidt hammer values are usually based on field test. When only core samples values are available, it is needed to change this value in to the in-situ intact rock value for the prediction of cutting rate of roadheaders or TBMs. For the derivation of the equations that change the core sample value in to the in situ intact rock value, different rock types were tested both in the field and in the laboratory by N-type Schmidt hammer. In the test, three different rebound-testing methods were applied on any rock type. The test results were interpreted statistically and significant linear relationships were found between in situ and laboratory Schmidt hammer values for all the test procedures employed. Therefore, the derived regression equations can practically be used for the prediction purposes with acceptable accuracy. Since all the testing in this research were made with the hammer held vertically downward and at right angles to horizontal rock faces, regression equations derived is valid for this case only.Since the rock types tested are hard rocks, further research is necessary to check the validity of the derived equations for soft rock.