The experience of geotechnical constructions and testing of piling foundations of megastructures on problematical soil ground of Kazakhstan

Currently, in the city of Astana, the construction of a Light Rail Transit (LRT) system is underway. This LRT project involves the development of an elevated dual-track railway line. The first phase includes the construction of a 22.4 km long overhead bridge with 18 stations. The foundation of the bridge consists of bored piles with diameters ranging from 1.0 to 1.5 meters and lengths between 8 and 35 meters. Ensuring the integrity of these deep foundations is of critical importance. Two non-destructive methods are commonly employed for quality control: the Low Strain Integrity Test (LSIT) and Cross-Hole Sonic Logging (CSL). This paper aims to analyze the advantages and limitations of both methods, using real-case applications from the construction of the LRT and other major infrastructure projects in Astana. The study includes the results of load testing on large-diameter bored piles, particularly those used in the Expo 2017 development. Static pile load testing remains the most reliable method to evaluate the load-settlement behavior of foundation piles. Test results from three different methods—Static Compression Load Test (ASTM), Static Load Test (GOST), and O-Cell Test (ASTM)—are presented and compared. The paper highlights the experience gained from applying these methods on piles with diameters of 1000 mm and depths of 31.5 m under challenging soil conditions. Based on the findings, practical recommendations are proposed for pile testing methods suitable for geotechnical conditions in Kazakhstan.