Assessment of Existing Bulkhead Walls for Dredging Impacts-Paper

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The paper presents a systematic approach to assessing existing bulkhead walls before dredging. Dredging removes soil that provides passive support at the wall’s toe, potentially increasing bending moments and anchor forces and causing local or global instability. These risks are especially difficult to assess for older walls with missing or incomplete construction records.<br /><br />Assessment begins with a review of available drawings, historical records, surveys, maps, and site information. Field inspections and measurements establish wall geometry, condition, corrosion, anchor configuration, shoreline slopes, and nearby loads. Where information remains uncertain, investigations may include land- and water-side borings, Standard Penetration Tests, undisturbed sampling, laboratory and in-situ soil testing, bathymetric or lidar surveys, parallel seismic testing to estimate pile length, and ground-penetrating radar to locate buried anchors and utilities. Historical steel properties should be considered when evaluating older walls.<br /><br />Analysis should account for variation in geometry, materials, soil conditions, and loading along the wall. Limit-equilibrium methods assess local stability, structural capacity, and global stability; nonlinear finite-difference or finite-element methods can better estimate soil–structure interaction and deformation near sensitive facilities. Key scenarios include existing conditions, each dredging stage, the final post-dredging condition, and—where relevant—rapid water-level changes such as seiche events. Both drained and undrained soil behavior may need evaluation.<br /><br />If the wall cannot safely accommodate dredging, potential measures include staged dredging and backfilling, added anchors or bracing, toe supports, or construction of a replacement wall. The preferred solution depends on site conditions, access, utilities, structural condition, and constructability. The paper emphasizes integrating investigation methods and engineering analyses to manage uncertainty and develop safe, practical dredging and stabilization plans.

Keywords

bulkhead walls

dredging

wall stability

anchor forces

soil investigation

structural assessment

finite element analysis

limit equilibrium

bathymetric survey

staged dredging