Two measurements, the indirect measurement with a dual-chambered FRI and the direct measurement with a field measurement of the Barton-Bandis model, for predicting hydraulic aperture at surface-exposed fractures in rock masses in situ are proposed in this study. An actual rock mass of jointed andesite rock on the Lan Yu site, Taiwan was studied. Results show that despite the substantial differences in the two techniques, results of the hydraulic aperture using the two measurements are comparable. The mean values appear to have the same order. This may be due to the fact that the fractures measured are relatively large (eg = 172 μm in the Barton-Bandis model and eg = 191 μm in the FRI experiment) and smooth (JRC = 3-05). The results are expected to be less favourable for tighter, rougher fracture. Although this work represents the estimated and comparable methods of the hydraulic aperture using the direct and indirect measurements, the true field condition can seldom be estimated exactly. In practice, estimation of the hydraulic aperture of a fractured rock mass cannot be based solely on surface-exposed rock fracture. Other in-situ hydraulic tests or tracer tests should be used to increase the validity of the results.
All Science Journal Classification (ASJC) codes
- Geotechnical Engineering and Engineering Geology
- Earth and Planetary Sciences (miscellaneous)