Determination of rock quality designation (RQD) in metamorphic rocks: a case study (Bayburt-Kırklartepe Dam)

Alemdağ, Selçuk; Sarı, Mahmut; Şeren, A.

doi:10.1007/s10064-022-02675-2

Cited by 15 publications

(3 citation statements)

References 17 publications

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“…Hasan et al 1 estimated RQD of tuff rocks using ERT measurements in Huizhou (China). Alemdag et al 48 determined RQD in metamorphic rocks of Bayburt-Kırklartepe Dam (Turkey) using P wave velocity (V p ) of SRT method. Johora et al 49 used artificial neural networks (ANNs) to predict geotechnical parameters from seismic wave velocity.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of rock mass units using a non-invasive geophysical approach

Hasan,

Shang,

Meng

2023

Sci Rep

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Thorough and accurate assessment of rock mass units is important for development of engineering infrastructures and groundwater resources assessments. Rock mass units are widely evaluated by reliable geomechanical parameters namely rock quality designation (RQD) and rock core index (RCI). Conventionally, these parameters are acquired via an extensive number of geotechnical tests. Such tests, however, suffer efficiency for data coverage, cost, equipment and topographic constrictions, and hence cause ambiguity in geological models for a detailed evaluation of rock mass integrity. Conversely, geophysical surveys offer fast, more user-friendly, less invasive, more cost-effective and less time-consuming approach for geological investigations. The past research confirms a useful link between geophysical and geotechnical parameters. But, none of the past studies provides a suitable and generalized relation between these parameters which can reduce geotechnical model uncertainty mostly caused by inadequate data and subsurface heterogeneity. This paper proposes a meaningful and feasible method to obtain geomechanical parameters using a certain number of drillings and geophysical data of four different sites. Based on electrical resistivity obtained from electrical resistivity tomography (ERT) and controlled-source audio-frequency magneto telluric (CSAMT), this research provides the general and adaptable formulas for geotechnical parameter estimation and reduces geological model uncertainty for more detailed 2D/3D imaging of RQD and RCI covering the whole sites where even no drilling data exists. Thus, the investigated sites are assessed laterally and vertically along each geophysical profile via distinct value ranges of geological parameters for a thorough and reliable evaluation of rock mass units in highly heterogeneous setting. Our research reduces the ambiguity caused by structural heterogeneities and scarce data, fills the gap between inadequate well tests and the true geological models, and gives new insights into the rock mass units for proper engineering design and groundwater exploitation.

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Section: Introductionmentioning

confidence: 99%

Evaluation of rock mass units using a non-invasive geophysical approach

Hasan,

Shang,

Meng

2023

Sci Rep

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“…Apart from seismic properties, the electrical resistivity of rocks is also well-distinguished, because in fractured rocks it derives from joint network and clay mineralization [17,18]. Compared with the traditional geotechnical approaches, geophysical methods provide non-destructive volumetric measurement, in a fast, user friendly and inexpensive way [19,20].…”

Section: Introductionmentioning

confidence: 99%

“…The exponent is a variable and must be determined on a case-by-case basis. Through trial and error, it was concluded that the best approximate fit for the considered data for exponent is 0.26 [20].…”

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confidence: 99%

Borehole Analysis with the Modification of RQD Value

Somodi,

Vásárhelyi

2023

Geotechnics

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The most common classification method of drill cores is the Rock Quality Designation (RQD) value, which indicates the percentage of rock cores longer than 10 cm in a given core section. This core logging procedure is the basic parameter in the most useful rock mass classification methods like Rock Mass Rate (RMR) and Rock Mass Quality (Q). It is also used to determine the Geological Strength Index (GSI), which has become widely used in the last 20 years. One of the basic problems of the RQD value is that it does not distinguish different rock cores longer than 10 cm (100% is obtained for one piece of 1 m length and 10 pieces of 10 cm length) and a uniform result is obtained for shorter units. In this paper, the so-called Integrated RQD (Int_RQD) factor is introduced to eliminate these problems and to provide a better description of fracture density in the core logging procedure. As it uses the original core logging procedure, historical RQD data can also be reevaluated. Considering that RQD is an input parameter for most rock engineering classifications, these systems such as GSI can be reviewed based on the new RQD definition proposed herein.

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