Method of determining the filtration heterogeneity of a rock mass of hydraulic structure foundation
Authors: Chernyshev Sergey Nikolaevich , Zommer Tat’yana Valentinovna , Lavrusevich Andrey Aleksandrovich 
Published: September 2016

N THE ARTICLE THE AUTHOR’S TECHNIQUE OF ESTIMATING THE FLOW HETEROGENEITY OF A ROCK MASS OF WATERWORKS FOUNDATION IS CONSIDERED. THE METHOD FOR ALLOCATING THE ENGINEERING-GEOLOGICAL ELEMENTS ON THE BASIS OF THE FILTRATION HETEROGENEITY OF ROCKY SOILS IS UPDATED ON THE EXAMPLE OF BOGUCHANSKAYA HPP ON THE ANGARA RIVER. THE AUTHORS INVESTIGATED THE APPLICABILITY OF THE PROPOSED METHODS FOR DETERMINING THE FILTRATION INHOMOGENEITY OF A ROCK FOUNDATION OF HYDRAULIC STRUCTURES IN ORDER TO BETTER HIGHLIGHT THE ENGINEERING-GEOLOGICAL ELEMENTS ON THE EXAMPLE OF THE BOGUCHANY HYDROELECTRIC COMPLEX. WHEN ANALYZING THE FACTUAL MATERIAL BY THE RESULTS OF ABOUT 1000 FILTRATION EXPERIMENTS FROM GEOLOGICAL CONSIDERATIONS AND IN ORDER TO SEPARATE THE DATA, WE HAVE IDENTIFIED THREE ROCKY SOIL MASSES. THE FIRST MASSIF IS THE RIGHT BANK OF THE FOLDED THICKNESS OF SEDIMENTARY ROCKS THAT SLOPE TOWARDS THE RIVER AND IS SUBJECT TO SIGNIFICANT SUPERGENE CHANGES. THE SECOND MASSIF INCLUDES UNDERFLOW AND LEFT-COAST SEDIMENTARY ROCKS, WHICH ARE LESS ALTERED BY SUPERGENE PROCESSES THAN THE RIGHT COAST FOR A NUMBER OF REASONS. THE THIRD ARRAY CONSISTS OF DOLERITE UNDER THE RIVERBED AND ON THE RIGHT BANK. FOR THESE THREE ARRAYS ACCORDING TO THE RESULTS OF THE FILTRATION EXPERIMENTS, WE HAVE BUILT HISTOGRAMS OF THE DISTRIBUTION OF LGQ AND DIFFERENTIAL CURVES OF DISTRIBUTION OF THE SPECIFIC ABSORPTION FOR DOLERITES IN THE AREA KODINSKY OF THE BOGUCHANSKAYA HPP. THEN IN THE HISTOGRAM WE IDENTIFIED THE CORRESPONDING VALUES OF THE MODAL COMPONENTS OF THE DISTRIBUTION AND FOUND THE STATISTICAL CHARACTERISTICS FOR EACH OF THE SELECTED DISTRIBUTIONS, AS WELL AS THE MEAN VALUE AND THE VARIANCE. FOR FURTHER OPERATIONS, WE COMPUTED THE STANDARD DEVIATION S FOR EACH OF THE DISTRIBUTIONS. THE DEGREE OF FRACTURE IS EVALUATED BY TAKING INTO ACCOUNT THE INDICATOR OF PERMEABILITY, THEREFORE, THE MAIN GEOLOGICAL CHARACTERISTICS OF THE CRACKS ARE THEIR WIDTH AND LENGTH, AND ONLY AFTER ALL THIS WILL TAKE INTO ACCOUNT THEIR FREQUENCY. THEN WE BEGIN SEARCHING THE LOCATIONS ON A SECTION OF FRACTURE ZONES, WHICH CORRESPOND TO THE COMPONENTS IN THE DISTRIBUTION FORMULA. SO WE DISTINGUISH THE SUMMANDS OF THE SUM ON THE FORMULA DISTRIBUTION: FOR SEDIMENTARY ROCKS OF THE RIVERBED - 3; FOR DOLERITE - 3; FOR A MASSIF OF SEDIMENTARY ROCKS ON THE RIGHT BANK WITH THE MOST COMPLEX STRUCTURE - 6 ZONES WITH DIFFERENT FRACTURE. THE DETERMINATION OF ZONES WITH DIFFERENT FRACTURING IN ACCORDANCE WITH THE DESCRIBED PROCEDURE ALLOWED US TO CONSTRUCT A RESULTING FILTRATION SECTION FOR THE THREE MASSIFS. AS A RESULT, ACCORDING TO THE ABOVE METHOD, BASED ON THE ANALYSIS OF FACTUAL MATERIAL, INCLUDING THE RESULTS OF NUMEROUS FILTRATION EXPERIMENTS, THE AUTHORS CONSTRUCTED THE RESULTING FILTRATION HYDROGEOLOGICAL SECTION. THIS TECHNIQUE IS STATISTICAL AND GENETIC IN NATURE, THEREFORE IT SEEMS MORE EFFECTIVE COMPARED WITH THE METHOD OF REGRESSION ANALYSIS RECOMMENDED IN THE APPENDIX TO SNIP. THUS, THE PROPOSED FORMALIZED METHODOLOGY FOR THE SEPARATION OF ROCK SOILS LOCATED AT THE BASE OF HPP TO INDIVIDUAL ENGINEERING-GEOLOGICAL ELEMENTS ACCORDING TO THE RESULTS OF EXPERIMENTAL MASS FILTRATION TESTING OF DRILLING WELLS HAS ALLOWED US TO ISOLATE THE HETEROGENEOUS FRACTURE PERMEABILITY AND GEOTECHNICAL ELEMENTS IN THE BASIS OF HPP (IN THE CASE OF THE BOGUCHANSKAYA HPP, WE HAVE IDENTIFIED 11 ENGINEERING-GEOLOGICAL ELEMENTS), AND ALLOWED US TO FIND THE BOUNDARIES OF ENGINEERING-GEOLOGICAL ELEMENTS IN GEOLOGICAL CROSS-SECTIONS. IN ADDITION, WE DETERMINED THE EFFECTIVE VALUES OF FILTRATION COEFFICIENT FOR EACH ENGINEERING-GEOLOGICAL ELEMENT INDICATING THE CONFIDENCE INTERVALS FOR THE MEAN VALUE AT THE 95 % CONFIDENCE LEVEL.