Research on hydraulic heaves at excavations with surcharge filters

摘要

When designing deep excavation pits next to waterways that are still being operated, verifying hydraulic heave safety is crucial to determine the necessary length of the pit walls. To reduce their embedment depth, a surcharge filter can be installed. However, studies based on numerical groundwater computations show that verification standards for hydraulic heave safety are not applicable for excavation pits with an installed surcharge filter. Standard approaches neglect significant vertical flow below the wall toe. A method which considers these flow forces was developed based on the numerical flow computations to determine reliably the necessary thickness of the surcharge filter. To examine this theoretical approach and the failure mechanism, several laboratory tests were performed which were evaluated with various methods.