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501.
Determination of joint roughness coefficient (JRC) for slope stability analysis: a case study from the Gold Coast area, Australia 总被引:1,自引:1,他引:1
Surface roughness of rock discontinuities is an important factor that determines the strength characteristics of rock mass. Joint roughness coefficient (JRC), which is typically measured by means of Barton’s combs in the field, is widely used to describe the joint roughness. However, this traditional method of measurement can be rather subjective, labor-intensive and time consuming. In contrast, photogrammetry can provide an alternative method to obtain relatively simple and fast measurements of JRC based on high resolution 3D models. However, the reliability of such measurements still remains an issue as the results from photogrammetry can be affected by the quality of images. This study seeks to clarify whether photogrammetry can produce accurate measurements of JRC that can be used to assess the stability of slopes. A rock slope with a recent wedge failure in the Gold Coast area, Australia was selected for this purpose, and three different methods such as manual measurements, photogrammetry, and tilt tests were employed to determine the JRC. The obtained results showed some discrepancy in the values of JRC obtained from these three different measurements. In particular, the JRC obtained using the Barton’s comb had slightly higher values compared to those determined through the photogrammetry method while the tilt test results tended to yield overestimated values of JRC. Computer analysis using Universal Distinct Element Code was also performed to study the effect of JRC variation on the slope stability. It was found that an increase in the JRC led to an increase in the safety factor of the slope. 相似文献
502.
The relationship of soil gas radon Rn222 and indoor radon was studied within the Quaternary fluvial sediments of the Czech Republic. The processing of data selection
from the radon database of the Czech Geological Survey and indoor radon data (database of the National Radiation Protection
institute) has proved the concentration dependence of radon in Quaternary fluvial sediments on deeper bedrock. The ArcGIS
processing was accompanied by the field verification in five profiles, intersecting the granitoid Central Bohemian Plutonic
Complex and its rim rock types. Both theoretical and experimental results show dependence of soil gas radon and indoor radon
concentrations in Quaternary fluvial sediments on deeper geological basement, thus leading to the conclusion that the lateral
transport of Quaternary sediments does not play such a dominant role in radon concentrations, as was thought previously. This
fact will enable to determine precisely the radon index of Quaternary sediments (in the Czech radon mapping classified as
an intermediate index) into three categories according to the lithology of their geological basement. 相似文献
503.
Monika E. Bailey George A. Isaac Ismail Gultepe Ivan Heckman Janti Reid 《Pure and Applied Geophysics》2014,171(1-2):257-276
An automated short-range forecasting system, adaptive blending of observations and model (ABOM), was tested in real time during the 2010 Vancouver Olympic and Paralympic Winter Games in British Columbia. Data at 1-min time resolution were available from a newly established, dense network of surface observation stations. Climatological data were not available at these new stations. This, combined with output from new high-resolution numerical models, provided a unique and exciting setting to test nowcasting systems in mountainous terrain during winter weather conditions. The ABOM method blends extrapolations in time of recent local observations with numerical weather predictions (NWP) model predictions to generate short-range point forecasts of surface variables out to 6 h. The relative weights of the model forecast and the observation extrapolation are based on performance over recent history. The average performance of ABOM nowcasts during February and March 2010 was evaluated using standard scores and thresholds important for Olympic events. Significant improvements over the model forecasts alone were obtained for continuous variables such as temperature, relative humidity and wind speed. The small improvements to forecasts of variables such as visibility and ceiling, subject to discontinuous changes, are attributed to the persistence component of ABOM. 相似文献