Research

Environmentally Enhanced Cracking

Cracking is ubiquitous in a geomaterial when it is subject to an environmental perturbation. Controlling environmentally assisted subcritical crack growth is the key enabler to a safe and active geo-energy adaptation to Climate Change, particularly in the strategic areas of unconventional shale hydrocarbon recovery, Carbon Capture Utilisation and Storage (CCUS) and enhanced geothermal systems (EGS). The aim of these applications is commonly to achieve an enhanced permeability and injectivity in the formation by the stimulation of hydro-fracturing. To maximize the effectiveness of the technique and meanwhile limit the extent of chemical footprint, a sophisticated understanding of the feedback between the mechanics of a geomaterial and the surrounding environment it is subject to is required. We develop modelling approaches on the effect of chemical environment on subcritical cracking in a stressed geomaterial at multiple scales, considering chemo-plasticity, chemo-elasticity and chemical ductilization.

Related papers:

Single fluid-driven crack propagation in analogue rock assisted by chemical environment
J. Chen^# and M. Hu^*. Geomechanics for Energy and the Environment, 2024. doi.org/10.1016/j.gete.2023.100526

Chemo-hydro-mechanics in a reactive rock under cylindrical fluid pressurization
X. Tang^# and M. Hu^*. Computers and Geotechnics, 2023. doi.org/10.1016/j.compgeo.2023.105637

A Reactive-Chemo-Mechanical Model for Weak Acid-Assisted Cavity Expansion in Carbonate Rocks
X. Tang^# and M. Hu^*. Rock Mechanics and Rock Engineering, 2022. doi.org/10.1007/s00603-022-03077-2

Modeling of subcritical cracking in acidized carbonate rocks via coupled chemo-elasticity
M. Hu^* and T. Hueckel. Geomechanics for Energy and the Environment, 2019. doi.org/10.1016/j.gete.2019.01.003

Influence of stress field anisotropy on drilling-induced tensile fracture
M. Hu^*, M. Veveakis, and K. Regenauer-Lieb. Environmental Geotechnics, 2018. doi.org/10.1680/jenge.17.00064

Environmentally enhanced crack propagation in a chemically degrading isotropic shale
M. Hu^* and T. Hueckel. Géotechnique, 2013. doi.org/10.1680/geot.SIP13.P.020

Bio-mediated Soils

Bio-improvement has emerged as a promising alternative approach for soil strengthening in recent years. Microbially induced carbonate precipitation (MICP), as the primary focus of research among all bio-inspired methods in the field of geo-environmental and geotechnical engineering, has achieved significant development from laboratory experiments to field tests as it is suitable for large-scale application, environment-friendly, energy-efficient, introducing minimal disturbance to the local ecology. We focus on the long-term resilience of a load-bearing MICP-treated soil, and hence take into account the influence of environmental acidification. We found with laboratory experiments that bio-cemented samples appear to be more “resilient” to an acidified aqueous environment in terms of less strength degradation in comparison to natural carbonate-rich rocks. We also found that by tuning the calcium carbonate content the bio-cemented specimen is likely to exhibit a ductile failure mode. Our current focus includes utilizing electro-chemical methods to enhance the bio-mediated mass precipitation, towards stronger and more resilient new geomaterials.

Related papers:

AC-assisted Microbially Induced Carbonate Precipitation for Soil Reinforcement: An Experimental Study
A. Tian^#, X. Tang^#, J. Chen^#, and M. Hu^*. Geomechanics for Energy and the Environment, 2024. doi.org/10.1016/j.gete.2024.100609

On the resilience of bio-cemented silica sands in chemically reactive environment
X. Tang^# and M. Hu^*. Geomechanics for Energy and the Environment, 2024. doi.org/10.1016/j.gete.2023.100527

Cross-diffusion Waves in Porous Media

Related papers:

Inversion of fluid-release rates from episodic tremor and slip signals in subduction zones via a coarse-grained reaction diffusion model
Q. Sun^#, K. Regenauer-Lieb, and M. Hu^*. Physics of the Earth and Planetary Interiors, 2024. doi.org/10.1016/j.pepi.2024.107223

Onsager’s reciprocal relationship applied to multiphysics poromechanics
K. Regenauer-Lieb^*, and M. Hu^*. Forces in Mechanics, 2023. doi.org/10.1016/j.finmec.2023.100213

Cross-scale dynamic interactions in compacting porous media as a trigger to pattern formation
M. Hu^*, Q. Sun^#, C. Schrank, and K. Regenauer-Lieb. Geophysical Journal International, 2022. doi.org/10.1093/gji/ggac115

Cross-diffusion waves resulting from multiscale, multiphysics instabilities: application to earthquakes
K. Regenauer-Lieb, M. Hu, C. Schrank, X. Chen, S.P. Clavijo, U. Kelka, A. Karrech, O. Gaede, T. Blach, H. Roshan, A.B. Jacquey, P. Szymczak, and Q. Sun^#. Solid Earth, 2021. doi.org/10.5194/se-12-1829-2021

Cross-diffusion waves resulting from multiscale, multi-physics instabilities: theory
K. Regenauer-Lieb, M. Hu, C. Schrank, X. Chen, S.P. Clavijo, U. Kelka, A. Karrech, O. Gaede, T. Blach, H. Roshan, and A.B. Jacquey. Solid Earth, 2021. doi.org/10.5194/se-12-869-2021

Cross-diffusion waves in hydro-poro-mechanics
M. Hu^*, C. Schrank, and K. Regenauer-Lieb. Journal of the Mechanics and Physics of Solids, 2020. doi.org/10.1016/j.jmps.2019.05.015

Multi-physics Instability in Geomaterials

The concept of tapping the Earth’s heat for generation of electricity or direct heating and cooling has charmed the modern-day civil engineers, for its clean, environment-friendly, renewable features. The conventional technique of hydraulic stimulation refers to generating a large tensile fracture with secondary fractures distributed around the primary fracture. Recently, shear stimulation as a less intrusive method has gained substantial attention, which creates a complex inter-connected fracture network around the injection hole that consists of generation and reactivation of shear cracks, covering reservoirs of a wide range permeability. We investigate the inception and growth of localized shear deformation around a cavity from a perspective of material bifurcation, extending the slip-line field into the Multiphysics realm. By relaxing the isothermal conditions, we derive temperature-dependent bifurcation criterion for the shear banding mode and infer the favoured injection conditions for shear stimulation at various depth.

Related papers:

A new mechanism for mineralizing systems based on cnoidal wave instabilities
C. Liu^#, V.M. Calo, L. Tannock, K. Regenauer-Lieb, and M. Hu^*. In review. 10.22541/essoar.169755035.59807837/v1

Understanding Earthquake Precursors: From Subcritical Instabilities to Catastrophic Events
K. Regenauer-Lieb and M. Hu^*. Physica Scripta, 2024. 10.1088/1402-4896/ad36f2

A thermodynamically based Modified Cam‐Clay model for post‐bifurcation behavior of deformation bands
Q. Sun^#, X. Chen, K. Regenauer-Lieb, and M. Hu^*. Journal of Geophysical Research: Solid Earth, 2024. doi.org/10.1029/2023JB028100

Emergence of precursor instabilities in geo-processes: Insights from dense active matter
K. Regenauer-Lieb and M. Hu^*. Heliyon, 2023. doi.org/10.1016/j.heliyon.2023.e22701

Shear instability in geothermal fields under hydromechanical feedback
J. Chen^#, X. Tang^#, and M. Hu^*. Geophysics, 2023. doi.org/10.1190/geo2022-0630.1

The dynamic evolution of compaction bands in highly porous carbonates: the role of local heterogeneity for nucleation and propagation
X. Chen, H. Roshan, A. Lv, M. Hu, and K. Regenauer-Lieb. Progress in Earth and Planetary Science, 2020. doi.org/10.1186/s40645-020-00344-0

The dynamic evolution of permeability in compacting carbonates: phase transition and critical points
X. Chen, K. Regenauer-Lieb, A. Lv, M. Hu, and H. Roshan. Transport in Porous Media, 2020. doi.org/10.1007/s11242-020-01493-y

Entropic limit analysis applied to radial cavity expansion problems
M. Hu^* and K. Regenauer-Lieb. Frontiers in Materials, 2018. doi.org/10.3389/fmats.2018.00047

The role of temperature in shear instability and bifurcation of internally pressurized deep boreholes
M. Hu^*, M. Veveakis, T. Poulet, and K. Regenauer-Lieb. Rock Mechanics and Rock Engineering, 2017. doi.org/10.1007/s00603-017-1291-2

Pattern Formation in Geo-systems

Self-organizing diffusion-reaction systems naturally form complex patterns under far-from-equilibrium conditions. Two representative patterns are rhythmic Liesegang stripes and fractal dendrites. However, the underlying mechanism for selecting the vastly different mineral precipitation patterns remains unclear. We use a phase-field model to reveal the mechanisms driving pattern selection in mineral precipitation and to invert for the important process parameters originating from the intrinsic material properties, such as the self-diffusivity ratio and mobility of rocks.

Others

Related papers:

Bidirectional Polytope Trees to Optimal Formation Path Planning for Reconfigurable Modular Robots
W. Lu and M. Hu. IEEE Transactions on Intelligent Vehicles, 2024. 10.1109/TIV.2024.3467948

Deciphering Immunodiffusion: In Silico Optimization for Faster Protein Diagnostics
C. Liu^#, S. Corrie, K. Regenauer-Lieb, and M. Hu^*. Talanta, 2024. doi.org/10.1016/j.talanta.2024.126385

Disturbance-aware reinforcement learning for rejecting excessive disturbances
W. Lu and M. Hu^*. Robotics and Autonomous Systems, 2023. doi.org/10.1016/j.robot.2022.104341

Reinforcement Learning for Autonomous Underwater Vehicles via Data-Informed Domain Randomization
W. Lu^*, K. Cheng, and M. Hu^*. Applied Sciences, 2023. doi.org/10.3390/app13031723

Markovian-Jump Reinforcement Learning for Autonomous Underwater Vehicles under Disturbances with Abrupt Changes
W. Lu^*, Y, Huang, and M. Hu^*. Journal of Marine Science and Engineering, 2023. doi.org/10.3390/jmse11020285

Zn(II) Removal with Activated Firmiana Simplex Leaf: Kinetics and Equilibrium Studies
Q. Tang, X. Tang, Z. Li, Y. Wang, M. Hu, X. Zhang, and Y. Chen. Journal of Environmental Engineering, 2012. dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000471

Removal of Cd(II) from aqueous solution with activated Firmiana Simplex Leaf: Behaviors and affecting factors
Q. Tang, X. Tang, M. Hu, Z. Li, Y. Chen, and P. Lou. Journal of Hazardous Materials, 2010. dx.doi.org/10.1016/j.jhazmat.2010.02.062