Numerical and Experimental Investigation of Mortar Placement Dynamics in Drilling Slurry for Cast-in-Place Concrete Piles

Abstract

This study investigates the dynamics of mortar placement in drilling slurry environments, a critical aspect of cast-in-place concrete piling. Mortar placement is affected by interactions with drilling slurry and sediment deposits, posing challenges such as segregation, void formation, and reduced structural integrity. This study uses experimental and numerical methods, integrating the moving particle semi-implicit (MPS) method, to simulate mortar–slurry interactions and validate the results with laboratory-scale tests. Controlled experiments replicated field conditions using drilling slurry with varying rheological properties and sediment content. The tests revealed that a portion of drilling slurry remained near the borehole wall, forming weak zones at the mortar–slurry interface. Additionally, convection currents influenced sediment redistribution, resulting in the accumulation of fine particles in the upper layers of the pile. Interface analysis indicated that these weak zones exhibited reduced compressive strength due to drilling slurry entrapment. Numerical simulations captured these dynamics and provided high-resolution visualizations of mortar–slurry interactions under realistic boundary conditions. The MPS simulations demonstrated that optimizing the tremie pipe placement could reduce sediment contamination by 25%–30%, improving structural integrity. This study highlights the importance of maintaining slurry quality and optimizing placement parameters, such as tremie pipe positioning and flow rates, to mitigate defects. Future work will focus on refining numerical models, real-time monitoring of grout quality, and sustainable construction practices. By addressing these challenges, this research contributes to more reliable and environmentally friendly geotechnical engineering solutions.