1st Edition
Practical Design of Ground Improvement with Rigid Inclusions
1. Rigid inclusion ground improvement system
1.1 The system and its components
1.2 Types of rigid inclusions
1.3 Interaction mechanisms
1.4 Identification of weak soils
1.5 Applications
1.6 Limitations
References
2. European regulations for ground improvement design
2.1 Introduction
2.2 Determination of the geotechnical category
2.3 Ground description
2.3.1 Ground Model and Geotechnical Design Model
2.3.2 Ground property values
2.4 Design verification
2.4.1 Limit states and their verification
2.4.2 Verification of ULS by the partial factor method
2.4.3 Verification of ULS by numerical methods
2.4.4 Verification of SLS
2.5 Traffic load models for geotechnical structures
2.5.1 Road traffic
2.5.2 Rail traffic
2.6 Design service life of geotechnical structures
References
3. Design of the rigid inclusion system
3.1 General guidance
3.1.1 Scope and context of ground improvement design
3.1.2 Practical flowcharts for the verification of ULS
3.1.3 Road traffic load models for embankments
3.1.4 Serviceability criteria for embankments
3.2 RI system geometry
3.2.1 Embankments
3.2.1.1 Arrangement of RIs
3.2.1.2 Embankment height
3.2.1.3 Pre-estimation of system geometry
3.2.2 Foundations and slabs-on-grade
3.2.3 Rigid inclusions
3.2.4 Caps
3.2.5 Load transfer platform
3.3 Working platform
3.4 Rigid inclusions
3.4.1 Selection of inclusion type
3.4.2 Numerical modelling of inclusions
3.4.3 Equivalent inclusion parameters in plane strain
3.4.4 External compressive resistance
3.4.4.1 Representative resistance
3.4.4.2 Design resistance
3.4.4.3 Group of inclusions
3.4.5 Structural resistance
3.4.5.1 Flexural behaviour
3.4.5.2 Concrete inclusions (EN 1992-1-1)
3.4.5.3 Mortar, grout or other concrete inclusions
3.4.5.4 Stabilised soil inclusions (EN 1997-3:2025)
3.4.5.5 Buckling resistance
3.4.5.6 Impact of geometrical imperfections
3.4.6 Reinforcement
3.4.7 Stability of fresh inclusion shaft
3.5 Ground–inclusion interaction under static loads
3.5.1 Vertical and moment loading
3.5.1.1 Load transfer functions
3.5.1.2 Load Transfer Method
3.5.1.3 Subgrade reaction coefficients
3.5.1.4 Moment loading
3.5.2 Lateral loading
3.6 Caps
3.7 Load transfer above inclusions
3.7.1 Load transfer platform (LTP)
3.7.1.1 Platform materials
3.7.1.2 Bearing resistance beneath rigid loading
3.7.1.3 Bearing resistance beneath flexible loading
3.7.2 Engineered fill/LTP with basal reinforcement
3.7.2.1 General load distribution scheme
3.7.2.2 Concentric Arches model
3.7.2.3 Klobe method
3.7.2.4 Extended load transfer model
3.8 Basal reinforcement
3.8.1 General guidance
3.8.1.1 Material options and product limitations
3.8.1.2 Vertical positioning and layering
3.8.2 Resultant tensile force
3.8.3 Design tensile force
3.8.4 Geosynthetic reinforcement
3.8.4.1 Basic design guidance
3.8.4.2 Tensile strength
3.8.4.3 Pull-out resistance
3.8.4.4 Anchorage length
3.8.4.5 Laying and joining
3.8.5 Steel mesh reinforcement
3.8.5.1 Basic design guidance
3.8.5.2 Tensile strength
3.8.5.3 Pull-out resistance
3.8.5.4 Laying and joining
3.9 RI system stability and compressive bearing resistance
3.9.1 Overall stability
3.9.2 Compressive resistance
3.10 Transition zones and buried utilities
3.11 Seismic design
3.11.1 General remarks
3.11.2 Seismic loading mechanisms
3.11.3 Soil-structure interaction analysis methods
3.11.4 Example of kinematic analysis with nonlinear bending
References
4. Lessons learned
4.1 Introduction
4.2 Working platform performance and consequences
4.2.1 Influence on occupational safety and rigid inclusion quality
4.2.2 Effects of excessive working platform heave
4.2.3 Effects of excessive working platform settlement
4.3 Potential construction defects in inclusions
4.3.1 Installation- and soil-related damage
4.3.2 Inclusion head formation
4.3.3 Installation of steel reinforcement
4.4 Damage to geosynthetic basal reinforcement
4.5 Examples of excessive deformations
4.5.1 Differential settlement of pavements
4.5.2 Settlement of a bioreactor
4.5.3 Settlement above wildlife culverts
4.5.4 Lack of control of ground improvement extent
4.5.5 Settlement at transition between different ground improvement methods
4.5.6 Lateral displacement of pad foundations with an LTP
4.5.7 Deformations of a high retaining MSE wall
4.6 Consequences of excavation base heave
4.7 Instability of embankments
4.7.1 Embankment failure at construction stage
4.7.2 Failure due to adjacent excavation
4.7.3 Good practices in embankment construction
4.7.4 Delayed collapse of a motorway embankment
4.8 Adverse effects of ground improvement on nearby structures
4.8.1 Displacement of a bridge abutment during construction
4.8.2 Displacement of piled pad foundations
4.9 Conditions associated with increased risk
References
5. Worked design examples
5.1 Introduction
5.2 Example A – Pad foundation
5.3 Example B – Road embankment on soft soil
5.4 Example C – Industrial floor supported on DSM columns.
Index
Biography
Michał Topolnicki graduated from the Faculty of Hydro-Engineering at the Gdańsk University of Technology in 1974, obtaining his PhD with honours from the same faculty in 1982. From 1982 to 1987, he was a research fellow at the Institute of Soil and Rock Mechanics at the University of Karlsruhe, where he published a habilitation thesis in the field of experimental and theoretical soil mechanics, which was awarded by the Polish Academy of Sciences in 1988. Upon returning to his home university, he was promoted to university professor in 1991 and to full professor in 2004. From 1994 to1998, he also ran his own design and management business, and, from 1996, was involved in the early development of the Keller branch in Poland. From 1999 to 2013, he was the CEO and chief designer at Keller Polska. From 2007 he was also responsible for the North East Europe region. In 2014, he became director of large projects at Keller Holding GmbH, overseeing the tendering and risk assessment of major construction projects. Since retiring in 2015, he has worked as a senior technical adviser to Keller and is now professor emeritus at his alma mater.
Michal has authored and co-authored several books and many publications, and is internationally recognised as an expert in ground improvement. He was involved in establishing design and execution guidelines for rigid inclusions and soil mixing in Poland, and in drafting the revised EN 14679. He co-chaired the last two International Conference on Deep Mixing, held in 2021 and 2025. At the ICSMGE conference in Sydney in 2022, he delivered the Louis Ménard Honorary Lecture on ground improvement. At the ECSMGE conference in Lisbon in 2024, he presented the keynote lecture on the interdependence between structural and geotechnical design.
