Research Projects

Internal erosion is a major cause of failure in embankment dams and flood protection structures worldwide. India has over 5,000 dams, many built using locally available geomaterials. Given the scale and criticality of this infrastructure, mitigating internal erosion is essential to ensure the long-term safety of embankment dams. Internal erosion is traditionally viewed as backward erosion or piping. However, recent understanding highlights that piping is only one mechanism. Other forms, particularly internal instability, involve the gradual migration of fines from the dam body, altering permeability and potentially triggering sinkholes or structural collapse. Unlike piping and surface scour, which can often be mitigated by design features, internal instability is less understood and harder to detect or control. Current field evaluations predominantly rely on geometric criteria based on particle size distribution, as reflected in Indian and international standards. However, emerging research emphasizes that internal instability is also governed by mechanical and hydraulic factors, particularly the load-sharing role of fines, stress state, and evolving pore structure. Despite these advances, current design approaches neglect mechanical and hydraulic criteria, stress state effects, and how these factors evolve under seasonal variations, which is particularly relevant for dams built along non-perennial river systems common in India. This proposal addresses these gaps through a multi-scale study of internal erosion, guided by three key objectives: (1) to investigate how stress state and principal stress orientation influence the initiation and progression of internal instability and associated mechanical behavior using advanced Hollow Cylinder Torsional testing, (2) to evaluate the effect of seasonal drying-wetting cycles on internal instability using a custom-designed experimental setup that simulates field-relevant boundary conditions. (3) to examine how pore structure and micro-structural features like force chains and fabric anisotropy evolve under varied stress paths, hydraulic conditions, and drying-wetting cycles using micro-CT, and to link these changes to field-relevant factors such as particle gradation, critical hydraulic gradients and stress state. The experimental program will thus be integrated with advanced image-based analysis, enabling a multi-scale investigation of internal instability. The final outcome will be a fabric-informed, multi-criterion framework for internal instability assessment that integrates geometric, mechanical, hydraulic, and stress path influences, including seasonal variations effects. The applicant brings relevant expertise in pore-scale modeling of two-phase flow and internal processes in granular media, while the mentor is a leading expert in image-based soil characterization in India. This collaboration promises impactful outcomes for improving the resilience of India’s dam infrastructure.