INSIDE Innovations on Stability Improvements

enabling Dyke Elevations

Dr P.R. Smith

A competition organised by:

The Problem

• Climate change leading to a rise of water level and hence need to raise dykes.

• Downstream reinforcement not desirable because of buildings.

• Upstream reinforcement not desirable because of the policy of ‘Space for the River’.

The Problem

Help! Is there nobody with a better solution?

Reference Location: Opperduit on River Nederlek

Situation circa1850

Situation today

The Challenge: Macro-stability

Loss of stability due to dyke raising and uplift during high water

The Challenge: Soil Profile

Typical soil profile of West Holland: 12 m weak cohesive soil on top of Pleistocene sand

Selection Criteria

• Minimum safety-factor of 1.2.

• Feasibility (materials, life span 50 to 100 years).

• Quality control methods for Mix In Place (MIP).

• Compatible with surroundings.

• Control and maintenance (sustainability).

• Cost

• Research Method Statement.

... AND THE WINNER IS....

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The consortium consists of:

2001 - Preliminary design

2002 - Final design (advanced modelling) - Validation phase (laboratory testing)

2003 - Practical phase (trial location, monitoring)

2004 - Evaluation phase (results published)

If feasible: technique implemented in Dutch design codes

The prize: Assessment of feasibility of MIP technique

The Solution

The Solution

•Location of MIP in toe or dyke slope.

•Influence on displacements (resistance against shear forces).

• Anchored in Pleistocene sand.

• Control over horizontal water flow.

Alternative arrangements of MIP Columns

3-D view Top View

Arching effect in MIP columns

Final Design: Advanced Modelling

PLAXIS 2-D: • interaction of soil with columns• shear strength of columns• inclination of columns• location of columns• displacements• groundwater flow

PLAXIS 3-D:

• arching in soil

Remaining Work

• 2002 - Final design (advanced modelling)

- Validation phase (laboratory testing)

• 2003 - Practical phase (trial location, monitoring)

• 2004 - Evaluation phase (results published)

INSIDE - Innovative Dyke Reinforcement - MIP

Thinking in all dimensions !

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