EXPERIMENTAL AND NUMERICAL ANALYSES OF A DEEP FOUNDATION CONTAINING A SINGLE DEFECTIVE PILE

Abstract

UNDERSTANDING OF FOUNDATION SYSTEMS IN TERMS OF SOIL-STRUCTURE INTERACTION HAS RECEIVED MUCH ATTENTION DUE PRIMARILY TO THE ADOPTED TECHNICAL APPROACH OF ANALYSIS, WHICH CAN BE READILY USED IN PRACTICAL DESIGN APPLICATIONS. HOWEVER, METHODOLOGIES FOR CALCULATING PILED FOUNDATIONS ARE COMPLEX SINCE THE SIMULTANEOUS (VARIABLE) INTERACTIONS AMONG THE BLOCK, PILES AND SURROUNDING SOIL SHOULD BE TAKEN INTO ACCOUNT. THEREFORE, IN ADDITION TO THE DISCUSSIONS ON CONSTRUCTION, INSTRUMENTATION, TESTING AND SIMULATION OF A DEFECTIVE PILE, THIS PAPER DISCUSSES THE PRACTICAL ISSUES ARISING FROM THE OBSERVED NUMERICAL AND EXPERIMENTAL OUTCOMES. THE MAIN ISSUES DISCUSSED IN THIS PAPER REFER TO AS THE DECREASE IN LOAD CAPACITY OF BORED INSTRUMENTED PILES WHEN SUBJECTED TO A STRUCTURAL DEFECT. THE STUDY CONSIDERED THE PERFORMANCE OF LABORATORY TESTS AND NUMERICAL ANALYSES USING THREE-DIMENSIONAL FINITE ELEMENTS; AND IN THE TEST, A BLOCK WAS FOUNDED ON THE TOP OF A DEFECTIVE PILE AND SUBJECTED TO A SLOW STATIC LOAD TEST. AS PREDICTED BY THE NUMERICAL ANALYSES, THE DEFECTIVE REGION STRUCTURALLY FAILED WHEN, DURING THE FIRST LOAD INCREMENT, IT WAS MOBILIZED BY A PRESCRIBED VERTICAL THRESHOLD LOAD. IT HAS BEEN ALSO OBSERVED THAT GIVEN THE PRESENCE OF THE DEFECT, THE FAILURE LOAD OF THE SYSTEM HAS DECREASED FROM 190 KN TO 110 KN, I.E. AROUND 40% REDUCTION OF THE INTACT REFERENCE VALUE. USING THE DATA OBTAINED BY NUMERICAL ANALYSIS, LABORATORY TEST, AND FIELD APPLICATION, IT WAS POSSIBLE THAT THE RESULTS WERE SATISFACTORY AND REASONABLE, ENHANCING OUR UNDERSTANDING OF THIS COMPLEX FOUNDATION SYSTEM’S BEHAVIOR, ESPECIALLY IN THE PRESENCE OF A DEFECTIVE PILE.