Punching Analysis of Underlying Karst Rock Foundation Considering Self-Weight of Rock Mass

Author(s):  
Ze-yu Liu ◽  
Yong Lei ◽  
Hao Tan
Keyword(s):  
2021 ◽  
Vol 8 (3) ◽  
Author(s):  
Ivan Khokhlov ◽  
Mikhail Zertsalov

Interaction peculiarities of a single unit bored pile with the surrounding rock mass under the horizontal load effect, as well as loss mechanism of piles bearing capacity, are considered. The article presents the numerical modeling results and a method developed on their basis for calculating piles in rocky soils under the horizontal load effect under the spatial elastic-plastic problem conditions, with the account of the contact behavior between the pile and the rock mass. The study of the single unit bored pile interaction and the surrounding rock mass under the horizontal and moment loads effect was carried out based on the numerical models’ analysis of the piles and the surrounding rock mass in a spatial setting using the finite element method. The use of regression analysis methods made it possible, to obtain parametric equations, based on the numerical modeling obtained results, that connected the studied response functions (bearing capacity and horizontal displacement of the pile) from preselected independent factors reflecting the geomechanical properties of the body and the design piles peculiarities. The developed calculation method allows at the preliminary design stage to estimate the horizontal pile displacement value, as well as its bearing capacity. Also, using the proposed technique, it is possible to make a piles load test schedule, which can be used in the field observation preparation at the design stage. The relevance of the topic is due to the fact that in modern construction practice, bored piles are used to transfer to the foundation significant loads, on the rock foundation from structures for various purposes, including transport (bridges and overpasses piers’ foundations, etc.).


Author(s):  
Suihan Zhang ◽  
Fredrik Johansson ◽  
Håkan Stille

AbstractGrout curtains are commonly constructed under dams to reduce the seepage through the rock foundation. In the design of grout curtains, empirical methods have mainly been used since the introduction of dam foundation grouting. Although empirical methods have been used with success in several projects, they have their limitations, such as poor control of the grout spread, only an indirect consideration of the threat of internal erosion of fracture infillings in the grouted zones, and the risk of hydraulic jacking. This paper presents a theory-based design methodology for grout curtains under dams founded on rock. In the design methodology, the grout curtain is designed as a structural component of the dam. The risk of erosion of fracture infilling material is explicitly accounted for along with the reduction of the hydraulic conductivity of the rock mass, and an optimization of the total uplift force. By applying the proposed design methodology, engineers can create a design better adapted to the prevailing geological and hydrogeological conditions in the rock mass, resulting in more durable grout curtains. The proposed methodology also enables cost and time estimates to be calculated for the grout curtain’s construction. Applying the principles of the observational method during the grouting execution also allows the design to be modified via predefined measures if the initial design is found to be unsuitable.


Vestnik MGSU ◽  
2016 ◽  
pp. 116-125
Author(s):  
Sergey Nikolaevich Chernyshev ◽  
Tat’yana Valentinovna Zommer ◽  
Andrey Aleksandrovich Lavrusevich

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.


2015 ◽  
Vol 35 ◽  
pp. 132-135
Author(s):  
Matteo Fiorucci ◽  
Roberto Iannucci ◽  
Luca Lenti ◽  
Anotnella Paciello ◽  
Alberto Prestininzi ◽  
...  

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