Instrumented Bidirectional Load Test to 157000kN for Deep Foundation Design

Abstract

Accurate assessment of the soil-pile structure interaction and distribution of soil resistance along the shaft is complex and indispensable in any civil engineering construction project. The invention and use of the Bi-Directional Static Load Test (BDSLT), a self-balanced biaxial test method, for the high capacity static load testing of deep bored piles gives an innovative and powerful quality control tool to check the initial pile design. BDSLT is now becoming common practice around the Middle East and global construction industry, more convenient, economical, safe and accurate than traditional top-down loading tests. The specially designed, calibrated, sacrificial hydraulic jacks, can be installed at the tip or within the desired stratum at any elevation on the reinforcement cage of a bored pile. It offers the required static loading virtually to any high loads without any overhead load frame or other external reaction systems. An attempt has been made to check the initial pile design values and the results of subsequent BDSLT carriedout for a 2000mm diameter deep foundation pile using bi-directional sacrificial jacks and Geokon embedded vibrating strain gauges to a test load of 157000kN at the proposed mixed-use high-rise tower project in Dubai, United Arab Emirates. The results show that the test pile was capable of sustaining ultimate shaft capacity due to the high shaft friction in the rock strata at a small settlement. This paper describes the installation and instrumentation of the pile, data analysis, and unambiguous information obtained, which can be directly applied to the permanent pile design procedure.