... strength can be observed covering areas from a few square meters to hundreds of square meters. When such features appear below buildings or roads it can produce catastrophic collapse. The changes of rock properties near the earth surface can be determined by geophysical measurements due to changes...

... of'Technology; Delft, Netherlands Abstract: The objective of our research is to obtain rock properties from acoustic measurements performed with acoustic tools in the borehole. To avoid the problems encountered in the field a laboratory measurement set-up, a borehole simulator and artificial reservoir rock have...

... and to determine rock properties. In a competent rock, the chances of recovery of intact core are relatively high, so rock properties can be determined in a biaxial compression test. In a closely jointed rock, however, the chances of recovery of intact core are much less. Even if overcoring has been successful...

... workings the lowest rock strength was observed on their contour. Rock strenght increased, with the distance from the contour being increased. To choose the type of support and to solve some other problems it is impotant to know changes of rock properties in time their stability. In this connection we...