The correlations between three different methods of measuring brittleness and both drillability and borability were statistically investigated using the raw data obtained from the experimental works of different researchers.
Strong exponential relationships between the penetration rates of tunnel boring machine (TBM) and the brittleness of B1 (the ratio of compressive strength to tensile strength) and B2 (the ratio of compressive strength minus tensile strength to compressive strength plus tensile strength) were found. There is no correlation between the penetration rates of the diamond drilling tool and the brittleness values. Strong exponential correlations exist between the penetration rates of rotary drills and the brittleness of B1 and B2. However, no correlation between the penetration rate of rotary drills and the brittleness of B3 (the product of percentage of fines in impact strength test and compressive strength) was found. The penetration rate of percussive drills does not exhibit a correlation with the brittleness of B1 and B2, but the penetration rate of percussive drills is strongly correlated with the brittleness of B3.
It was concluded that each method of measuring brittleness has its usage in rock excavation depending on practical utility. 相似文献
Measures of local relief, regional relief, and slope were calculated from digital elevation models (DEMs) for 50 bedrock units in the Ridge and Valley and Blue Ridge provinces of Tennessee. Each of these measures was normalized and the three were then averaged to produce the erosional resistance index (ERI). Bedrock units with higher ERI values include coarse clastics, intermediate clastics, and metaplutonics. Units with lower values include shales, limestones, limestones plus dolostones, and carbonates plus fine clastics. Dolostones tend to have intermediate values. The calculated ERI values were compared with subjective ratings by a geologist with decades of field experience in east Tennessee. Generally, the agreement between the two ratings was good, the most glaring exception being several shales with improbably high ERI values. These turned out to be thin units cropping out beneath very hard sandstones, allowing them to stand higher and steeper than would otherwise be possible. A systematic method for detecting such erroneously high ERI values is suggested. Inspection of a drainage map superimposed on the geology map shows that in a given area, streams tend to flow on rock units with the lowest ERI values. In addition, statistical analysis shows that bedrock units with the lowest ERI values are, on average, almost three times closer to the nearest stream and six times as likely to have streams flowing on them than are units with highest values. Further, the effect of ERI on stream location is strongest for streams with drainage areas between 1 and 30 km2. Thus, small streams appear to be subject to greater lithologic control than are larger streams. 相似文献
