Analyzing Wall Failure in Mud-Capped Dredge Pits along the Louisiana Continental Shelf

Document Type

Conference Proceeding

Publication Date

1-1-2025

Abstract

Offshore sediments serve as valuable sand resources essential for nourishment and restoration projects in coastal Louisiana. However, dredging of these offshore sediments creates dredge pits that gradually fill with fine materials, and the stability of these pit walls poses potential geohazards to nearby offshore infrastructure. In this study, a recent wall failure within the Sandy Point dredge pits, located near the Mississippi River Delta Front (MRDF), is investigated. Situated in a dynamic sedimentary environment and repeatedly impacted by storms, Sandy Point has experienced significant effects from multiple hurricanes in recent years. The primary objective of this research is to conduct a slope stability analysis to determine the causes of the collapse. To achieve this, bathymetric data, subbottom profiling, and core samples are integrated to analyze the wall failure. High-resolution subbottom and bathymetric data collected before and after the failure allow for precise delineation of the failure plane and analysis of subsurface changes linked to instability. Sediment cores collected from the pit edges are used to determine sediment shear strength through Triaxial testing, providing critical geotechnical parameters for the analysis. An inverse analysis is then performed to identify potential triggers, including hurricane-induced wave loading and progressive sediment weakening. This study offers valuable insights into the stability challenges facing dredge pits in hurricane-prone regions, supporting enhanced risk assessment and management strategies for coastal sediment management and restoration projects.

Publication Source (Journal or Book title)

Geotechnical Special Publication

First Page

57

Last Page

66

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