ROCK MECHANICS · SUBSURFACE ENERGY

Shangtong Yang

Professor

Professor, China University of Mining and Technology, Xuzhou, China

Reader, University of Strathclyde, Glasgow, UK

We research subsurface energy flow through natural and engineered rock systems

Academic Service

Academic committees

Co-Chair, ISRM Commission on Subsurface Energy Storage
Member, International Advisory Committee of 16th International Conference on Fracture (ICF-16)
Member, International Scientific Committee of 10th International Symposium on Life-Cycle Civil Engineering (IALCCE 2027)
Member, International Scientific Committee of 9th International Symposium on Life-Cycle Civil Engineering (IALCCE 2025)
Member, ASCE Engineering Mechanics Institute UK Programme Committee
Fellow, UK Higher Education Association

Editorial service

Editorial board member, International Journal of Rock Mechanics and Mining Sciences
Editorial board member, Scientific Reports
Guest editor, Tunnelling and Underground Space Technology, special issue in New Advances in Underground Energy Storage Systems
Guest editor, Journal of Rock Mechanics and Geotechnical Engineering, special issue in Theory and Intelligent Control Technology of Dynamic Disasters in Deep Earth Resource Development
Guest editor, Deep Underground Science and Engineering, special issue in Geoenergy and Subsurface Engineering toward Net Zero: Recent Advances and Emerging Applications

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Research

Rock fatigue and fracture

In-situ XCT DVC analysis

We investigate how internal microcracking and local deformation govern the macroscopic failure and hysteresis of crystalline rock. In-situ X-ray computed tomography (XCT), quantitative void segmentation and digital volume correlation (DVC) connect evolving three-dimensional crack networks with internal strain fields. Through uniaxial compression of fine granite, we have revealed the nucleation of isolated microcracks followed by unstable coalescence, with damage evolving from predominantly inclined cracking towards a stronger contribution from load-parallel cracks near failure [paper]. Moreover, a complete cycle of Loading–unloading–reloading observations link the mechanical hysteresis to delayed strain release in dilation zones associated with shear cracking, and reveal additional damage before the previous peak load is regained [paper]. These observations underpin micromechanical models of damage accumulation and rock fatigue.

Fatigue constitutive modelling

We have developed constitutive descriptions that connect cyclic loading histories to progressive damage and fracture in rocks and other quasi-brittle materials. An S–N-based fatigue degradation law was first coupled with a fluid cohesive crack model for hydraulic rock fracture [paper]. The subsequent nonlinear cyclic cohesive zone model distinguishes fatigue driven irreversible displacement from static damage induced stiffness loss, with fatigue evolution governed by the current stress and damage state [paper]. Validation against concrete three-point bending tests reproduces crack initiation, stable growth and rapid fracture, and captures loading sequence effects that linear cumulative damage rules cannot represent. Together, these developments can provide a framework for modelling fatigue-controlled fracture across quasi-brittle materials.

Hydraulic stimulation technologies

Fatigue-inspired hydraulic pulse stimulation

We explore how controlled hydraulic pulses can initiate rock fractures at lower pressure while managing subsequent crack growth. A finite element framework couples S–N based fatigue degradation, cohesive fracture, fluid flow and pore pressure, validated against laboratory pulsating fracture results [paper]. In the modelled cases, pulses reduce breakdown pressure by 10–18% over 10–4,000 cycles of applied pressure. The simulations also show that pressure controlled pulses can drive rapid crack growth after initiation. A three stage strategy is proposed to switch from high frequency pressure pulses to flow controlled cyclic injection, then lowers frequency while increasing the flow as the fracture extends. The resulting simulations demonstrate slower and steadier propagation and identify how injection control can exploit fatigue without losing control of fracture growth.

Near-wellbore fracture control and natural fracture activation

We investigate how well construction, perforations and existing fractures shape hydraulic stimulation near the wellbore. A coupled analytical–numerical model represents pressure transmission through the casing–cement–rock system, while a hydro-mechanical mixed-mode cohesive model incorporates frictional slip on natural fractures [paper]. The studies show that larger pressure transmission reduces near-wellbore fracture deflection but raises breakdown pressure. Hydraulic–natural fracture interactions reproduce crossing, deflection and offsetting; deflection is shear-dominated, and the outcome depends on approach angle, fracture strength, in-situ stress and injection conditions. In the simulated near-wellbore configurations, low injection rates can favour the natural fracture activation, providing a mechanistic basis for well design and stimulation planning [paper].

Subsurface energy storage systems

Lined rock caverns energy storage

We assess the integrity of lined rock caverns by resolving interactions between the steel barrier, concrete lining and fractured host rock. A phase-field framework combines mixed-mode cracking, frictional contact, steel plasticity, discrete fracture networks and spatial material variability [paper]. The simulations reveal a design trade-off: stronger concrete improves overall confinement but can concentrate cracking and transfer local strain into the steel lining. Fracture connectivity controls how damage spreads into the rock, while greater burial depth increases confinement and suppresses crack opening. Pressure–depth maps quantify these competing effects and support site specific operating limits.

Thermal energy storage

We connect the energy performance of subsurface thermal stores with the durability of their containment materials. Lifetime thermo-economic modelling couples flooded mineshaft water, surrounding ground and district-heating demand: in the cost-optimal scenarios studied, daily-to-weekly operation keeps heat losses below 10% of input energy, whereas seasonal storage incurs much larger losses [paper]. Complementary thermo-chemical experiments investigate mortar lining under 15–55 °C cycling and 3 wt.% sulphate exposure. The combined conditions produce severe accelerated deterioration, with leaching and ettringite formation creating depth dependent stiffness and thermal deformation that promote cracking during cooling [paper]. These studies show why operational optimisation and material degradation must be evaluated together when planning longer service life thermal storage.

Whole life-cycle management and AI application

Environmental deterioration and performance evolution

We develop mechanistic models linking environmental deterioration to cracking and serviceability loss in reinforced concrete structures. A von Mises-based corrosion model developed describes the non-uniform growth of rust around reinforcement and supplies expansion to mesoscale fracture models containing aggregates, mortar and interfacial transition zones [paper]. The simulations capture microcrack initiation at interfaces, coalescence into surface cracks, and toughening through crack deflection, aggregate bridging and microcrack shielding. Mixed-mode analysis shows that a uniform-corrosion assumption can delay predicted surface cracking and underestimate crack width, particularly for thicker covers [paper]. These results can provide a basis for interpreting damage evolution and assessing the durability of concrete infrastructure and containment systems.

Machine-learning inspired analysis

We combine physics based fracture simulations with machine learning for parameter identification and time-dependent reliability assessment. An artificial neural network trained on mesoscale tensile simulations inversely identifies concrete interface strength and fracture energy from measured stress–displacement curves, reproducing the RILEM benchmark across different aggregate arrangements [paper]. A complementary surrogate-assisted reliability framework links non-uniform corrosion, crack width predictions and Monte Carlo sampling to estimate serviceability failure over time [paper]. In the worked example, accounting for non-uniform corrosion shortens the remaining safe life after corrosion initiation by about 32% relative to a conventional uniform model. These approaches translate detailed mechanics into efficient tools for material calibration and maintenance decisions, within the validated modelling conditions.

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Recent journal publications

* Corresponding author

2026

Journal of Energy Storage, 2026, 182, 124673

Deterioration mechanisms under combined low-amplitude thermal-fatigue and sulphate attack of concrete lining materials for underground thermal energy storage

Wang H., Yang S.*, Flude S., Burnside N., Mukherjee I., Ewe W.E., Flett G., Tuohy P., Dassow J., Molnar I., Shipton Z.K..

Shangtong Yang

Academic Service

Academic committees

Editorial service

Research

Rock fatigue and fracture

In-situ XCT DVC analysis

Fatigue constitutive modelling

Hydraulic stimulation technologies

Fatigue-inspired hydraulic pulse stimulation

Near-wellbore fracture control and natural fracture activation

Subsurface energy storage systems

Lined rock caverns energy storage

Thermal energy storage

Whole life-cycle management and AI application

Environmental deterioration and performance evolution

Machine-learning inspired analysis

Recent journal publications

2026

2025

2024

Team

Postdoctoral researcher

Dr Dongsheng Chen

PhD students

Zhiming Feng

Jucan Yao

Kangda Chen

Tianran Lin

Bin Yao

Bo Yang

Ruiyu He

Master’s students

Yuhui Gong

Yunfei Yang

Tianle Zhu

Yilei Kong

Lujia Li

Zhenyu Wu

Past group members

Vacancy

Research opportunities

Contact & collaboration

Team@CUMT, Xuzhou, China