STUDY OF INFLUENCE OF «PILE–SOIL» SYSTEM PARAMETERS ON THE ACOUSTIC SIGNAL DYNAMIC ATTRIBUTES USING NUMERICAL MODELLING

Abstract

The relevance of the researchis caused by necessity to improve the efficiency of using non-destructive pile testing methods. The directions of research in this area are to determine the capabilities and limitations of standard approaches and to propose the new methods that allow obtaining new information about the structures. The robust estimation of pile integrity and bearing capacity obtained at the stage of quality control of the structures prior to their commissioning minimizes the subsequent risks of capital expenditures for eliminating emergency consequences.Common geophysical quality testing methods are designed to study the material of structures. The modification of the low strain impact method described in the publication suggests using additional information extracted from acoustic signals for a comparative assessment of the contact conditions of piles. This allows meeting the requirements of GOST 5686-2012 «Soils. Methods of field testing by piles» on the conducting static load tests, increasing the predictive efficiency of the complex of field tests in capital construction. The main aim of the research is to study the general patterns in the behavior of the sonic signal dynamic attributes associated with the features of the «pile–soil» system. Objects of the research are reinforced concrete piles and other deep foundations. Methods: low strain impact method; attributes analysis of acoustic signal, numerical modelling of elastic waves propagation. Results.The authors have proposed the technique for comparative assessment of contact conditions, based on the analysis of alow strain impact method signals using the dynamic attributes of the normalized spectrum square and the average-weighted frequency. Nine series of numerical models were compiled describing common «pile–soil» systems. A three-dimensional numerical simulation was performed, attributes were calculated for the obtained synthetic signals and attribute diagrams were constructed. Conclusions are drawn about the influence of changes in the parameters of the «pile–soil» system on the behavior of dynamic response attributes.

Keywords

• pile testing
• low strain impact method
• acoustic emission
• acoustic contact
• bearing capacity
• numerical simulation
• non-destructive testing