VERIFICATION OF THE ACCURACY OF THE MODEL FOR PREDICTING STRENGTH OF SEDIMENTARY ROCKS OF SOUTHERN YAKUTIA BASED ON GEOMETRIC ELECTROMAGNETIC INDUCTION SOUNDING
L.G. Neradovskii
Melnikov Permafrost Institute, Siberian Branch of the Russian Academy of Sciences, Yakutsk, Russia
Keywords: model for Neryungri City, sedimentary rocks, rock mass and laboratory samples, saturated rock strength, geometric electromagnetic induction sounding, verification, error
Abstract
This article discusses the results of retrospective verification of the strength prediction model for saturated rocks of southern Yakutia. The model was developed for the geotechnical conditions of the city of Neryungri. The input data for the model consisted of the decay rate coefficients of the harmonic field of a vertical magnetic dipole measured at a 1.125 MHz frequency using the geometric electromagnetic induction sounding method. The error of model predictions was close to the allowable error of ±20 % for average laboratory estimates of rock sample strength and ranged from ±16.8 to ±33.5 % for different site conditions with a probability of about 70 %. The total error of the model at this probability is 27.2 % with maximum outliers overestimating the laboratory strength of weak rocks by 120.5 % or underestimating the strength of strong rocks by 86.8 %. The model predictions were more accurate (errors of 22.8 and 21.9 %) for the rock masses composed predominantly of moderately strong (15-50 MPa) and strong (50-120 MPa) rocks. The statistical results indicate that the model is regionally representative and can be applied in the areas of warm and cold permafrost sedimentary rocks of southern Yakutia for rapid, cost-effective terrain evaluation by rock strength.
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