کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5787040 1641105 2017 15 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
In-situ GPR test for three-dimensional mapping of the dielectric constant in a rock mass
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات فیزیک زمین (ژئو فیزیک)
پیش نمایش صفحه اول مقاله
In-situ GPR test for three-dimensional mapping of the dielectric constant in a rock mass
چکیده انگلیسی


- Insertion of steel rods, acting as synthetic reflectors, in a vertical face of a rock mass
- The velocity of propagation was modeled in pathways from the hyperbolic reflections.
- The dielectric constant was modeled and mapped for a volumetric rock mass.
- The dielectric constant randomly varies in the micro and macro scale of a rock mass.
- The proposed method can be useful in signal processing programs.

The Ground Penetrating Radar (GPR) is used to detect subsurface anomalies in several applications. The more the velocity of propagation or the dielectric constant is estimated accurately, the more the detection of anomalies at true subsurface depth can be accurately obtained. Since many GPR applications are performed in rock mass with non-homogeneous discontinuous nature, errors in estimating a bulk velocity of propagation or dielectric constant are possible. This paper presents a new in-situ GPR test for mapping the dielectric constant variability in a rock mass. The main aim is to investigate to what extent the dielectric constant is variable in the micro and macro scale of a typical rock mass and to give attention to GPR users in rock mass mediums. The methodology of this research is based on the insertion of steel rods in a rock mass, thus acting as reflectors. The velocity of propagation can be then modeled, from hyperbolic reflections, in the form of velocity pathways from antenna positions to a buried rod. Each pathway is characterized by discrete points which are assumed in three dimensions as centers of micro cubic rock mass. This allows converting the velocity of propagation into a dielectric constant for mapping and modeling the dielectric constant in a volumetric rock mass using a volumetric data visualization software program (Voxler). In a case study, 6 steel drilling rods were diagonally inserted in a vertical face of a bench in a sandstone quarry. Five equally spaced parallel lines, almost perpendicular to the orientations of the rods, were surveyed by a dual frequency GPR antenna of 200 and 600 MHz. The results show that the dielectric constant is randomly varied within the micro and macro scale either in single radargrams or in the volumetric rock mass. The proposed method can be useful if considered in signal processing software programs, particularly in presence of subsurface utilities with known geometry and dimension, allowing converting double travel time, through portions of a radargram, into more reliable depths using discrete dielectric constant values instead of one value for a whole radargram.

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ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Applied Geophysics - Volume 146, November 2017, Pages 1-15
نویسندگان
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