INSIDE Innovations on Stability Improvements enabling Dyke Elevations

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 today Situation circa 1850

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. . The consortium consists of: . The prize: Assessment of feasibility of MIP technique 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 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 Arching effect in MIP columns Top View

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 !