Geological hazards are changing. ‘Emerging Geohazards’ are hazards that, based on the current state of science, are unlikely to happen! They though take place, claim lives and damage the built environment! These new hazards are mainly driven by anthropogenic (i.e. man-made) alterations to the total environment (atmosphere, biosphere, lithosphere) as the consequence of urban sprawl, and degradation of ground natural functions (i.e. ecosystem service provision). Footprints of man-made ground disturbance are ubiquitous in soil fabric, fatigue, and formation of non-authigenic complex cementitious minerals, all causing uncertainty, anomalies, and variability of soil properties. In this, the grand challenge is that while the identity of many young non-authigenic mineral forms and their association with geohazards may be known, in many cases their function in today’s active total environment remains obscure. I study these new mineral forms, their metastability, and interconnected hazards that are caused by them.
In doing so, I study the mechanisms of problems at micro scale. I do this to collect geochemical, micromorphological, and microstructural data at particle-level. The data is then translated into structure-based micromechanical models, some that I have developed over the past years. This helps me to associate the macro-scale testing data with micro-scale events.
This approach allows the design and testing of bespoke preventive and corrective measures which in the majority of cases include chemical modifications at particle-level. Such modifications are made through changes to soils’ pore fluid (through controlled soil gassing, electrokinetics, …), injection of low-viscose grouts, or deep-mixing for new developments. Additives include a range of Organic (e.g. Pectin-rich plants and food production wastes), Biogenic (e.g. decayed plant rootlets), Pseudo-Biogenic (or new young polymorphs, call these Anthroportācarbs), Inorganic (nano-silica hydrosols, polybutadiene, polyisoperne, elastomers and styrene-butadiene) solid matters, many of which present naturally in shallow grounds. In this, I share an interest with academics studying nature-inspired self-healing technologies. My overarching vision is developing, measuring, and deploying a set of proxy parameters of soil to make a more informed decision in choice and implementation of ground engineering techniques, to revitalize and restore the symbiosis between natural systems and engineering interventions, and to ensure interventions are adaptable to emerging environments.
I have also some interest in computational geomechanics: Probablisitic analysis of deep excavations (combining statistical methods such as Random Field, Monte Carlo, or Point Estimate, and Finite Element analysis); and also the development of hybrid Finite Element – Finite Difference codes for deformation analysis of fractured rocks, an example being the Continuum Analysis 2D, a non-commercial TMU code first developed in 1996 (BHRC Report no. 262, 1997) and then updated by myself and my partners. The CA2 offers dynamic stress-strain analysis and crack propagation through solid-fluid interaction and ideally suits the design of underground structures and hydro-fracture.
My current emphasis is on improving our probabilistic models. I believe that ground mechanical properties and hydraulic actions (i.e. groundwater flow) in urban settings are highly variable and only a stochastic analytical framework can offer an accurate prediction of ground movements caused by excavation, tunneling, or earthworks.