Cellular Sheet Pile Retaining Walls with Unconnected Tail Walls

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Solution Overview

Problem

Conventional sheet pile retaining systems face high construction costs, instability due to deep toe embedment requirements, and vulnerability to scour and seismic events, especially in harsh marine environments like Alaska.

Innovation Solution

A cellular sheet pile retaining system with unconnected tail walls, where the tail walls are deeper and longer than the face walls, providing additional anchoring support and reducing the distance they extend from the face wall, thus enhancing stability and reducing material needs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If tied back sheet pile walls are used with deep toe embedment, then lateral retaining strength is improved, but construction complexity and cost increase due to excavation and deep anchoring requirements

Engineering Contradiction:

Improvelateral retaining strengthVSAvoidconstruction complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The retaining wall is divided into modular cellular compartments formed by interconnected sheet piles. Each cell can be independently constructed and filled, allowing progressive installation without requiring deep excavation or complex anchoring systems. The modular approach breaks down the complex task of creating a deep-founded wall into simpler, sequential cell construction steps.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of relying solely on deep vertical embedment for stability, the system utilizes the horizontal dimension by creating interconnected cellular structures. The cells are filled with backfill material that provides mass and stability, transferring loads through the cellular network rather than requiring each individual pile to be deeply embedded like traditional tied-back walls.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Strength

If closed cell flat sheet pile structures are used, then retaining support is improved, but construction cost increases due to multiple templates and close tolerances

Engineering Contradiction:

Improveretaining supportVSAvoidconstruction cost

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The sheet pile structure incorporates flexible connections and adaptable cellular configurations that can accommodate field variations without requiring strict adherence to predetermined templates. The system allows for dynamic adjustment during construction, eliminating the need for multiple rigid templates and close tolerance requirements while maintaining structural integrity.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system allows variation in cell geometry, size, and configuration based on site conditions rather than requiring uniform closed-cell structures. By changing parameters such as cell dimensions, arrangement patterns, and sheet pile orientations, the system achieves retaining support with simpler construction procedures and reduced template requirements.

Inventive Principle:

Principle #35Parameter changes

3Strength

If tied back walls are used, then load capacity is improved, but vulnerability to scour and seismic failure increases due to exposed connections

Engineering Contradiction:

Improveload capacityVSAvoidvulnerability to scour and seismic failure

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The sheet piles are interconnected to form continuous cellular structures where the walls of adjacent cells are joined together. This merging creates a unified, interlocked system that distributes seismic forces and resists scour across the entire structure rather than leaving isolated vulnerable connection points. The interconnected cells work together as a single structural unit, improving overall reliability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The cellular configuration with interlocked walls transforms potential vulnerability points into strength zones. The connections between cells, which could be weak points in traditional structures, become reinforced through the interlocking action and shared load paths. The system converts what would be vulnerable exposed connections into protected, load-distributing joints within the cellular network.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS11149395B2Cellular sheet pile retaining systems with unconnected tail walls, and associated methods of use

Publication Date: 2021.10.19 PND ENGINEERS

AI summary

Embodiments of the disclosure are directed to cellular sheet pile retaining wall systems with unconnected tail walls, and associated methods of use and manufacture. In one embodiment, a retaining system includes a face wall having a plurality of interconnected face wall sheet piles. The individual face wall sheet piles have a first length and extend a first depth into soil, and the face wall sheet piles form an exterior surface facing an exterior environment. The system also includes a tail wall including a plurality of interconnected tail wall sheet piles extending from the face wall away from the exterior environment. The individual tail wall sheet piles have a second length greater than the first length, and the individual tail sheet wall piles extend a second depth into the soil that is greater than the first depth.