PERFORMANCE OF SHALLOW FOUNDATIONS ON WATER-SATURATED CLAY SOILS AND THEIR REINFORCEMENT USING MICROPILES: A CASE STUDY IN ASTANA

Abstract

The relevance of this topic stems from the need to ensure the reliable performance of shallow foundations in conditions of weak, water-saturated clay soils and high groundwater levels, which are characteristic of the northern regions of Kazakhstan. The objective of this study is to investigate the performance characteristics of shallow foundations and to evaluate the effectiveness of their reinforcement using micropiles in complex engineering-geological conditions. The scientific novelty of the study lies in a comprehensive approach that includes field surveys, analytical calculations using the BASE software package, and numerical modeling in the PLAXIS 2D environment for a real-world site, taking into account the interaction of the “subgrade–foundation” system under high groundwater levels. The calculations showed that the existing strip foundations are operating near the ultimate limit state in terms of deformation (K = 0.98), while a sufficient safety margin remains in terms of strength (K = 0.79). Numerical modeling showed that foundation deformations are primarily determined by the compressibility of the upper weak soil layer. The use of micropiles significantly reduces settlement and redistributes stresses to deeper and stronger layers. Numerical modelling showed that the maximum settlement of the existing foundation reached about 40 mm. After reinforcement with micropiles, settlement decreased to 3.3 mm, demonstrating a substantial improvement in foundation performance. The results confirm the effectiveness of micropiles for strengthening shallow foundations in weak soils and high groundwater conditions. The proposed approach can be applied to the design and rehabilitation of buildings in complex engineering-geological and urban environments.