This fully funded PhD position at Université Grenoble Alpes, supported by the Marie Skłodowska-Curie COFUND (PhD@Tec21), investigates the biogeomechanics of root growth in soils, with a particular focus on the multiscale hydromechanics at the root-soil interface. The project aims to bridge biophysics and soil mechanics by developing a unified multiscale and multiphysics model to describe the hydro-mechanical behavior of the root-soil system. Research will be conducted jointly at the 3SR laboratory (Geomechanics group) and the LIPhy laboratory (MC2 group) on the Grenoble campus. The 3SR group offers expertise in soil hydro-mechanics, granular and porous media, and advanced 3D imaging, while LIPhy specializes in the biophysics of living systems and modeling of cell and tissue dynamics. The PhD student will work closely with five researchers from these labs, benefiting from their technical support and collaborative environment. The project is structured around two main research axes: (1) studying the dynamics of water transport from soil to root, including the effects of mucilage and the extension of poromechanical models, and (2) investigating the multiscale mechanical interactions between roots and soil, modeling how cell-level processes affect root elongation and soil deformation. The research will involve advanced numerical simulations (FEM, DEM), analytical modeling, and validation using 4D X-ray and neutron tomography. Applications of this research include sustainable agriculture (root water uptake, soil compaction), civil engineering (bio-inspired soil stabilization), and robotics (soil-penetrating robots). The position offers a 36-month full-time contract with a competitive salary (gross 2,669 EUR/month, net 2,050–2,152 EUR/month), full social security, health insurance, doctoral training, and opportunities for secondments at partner institutions in the UK, Netherlands, Spain, and Italy. Additional benefits include access to high-quality research facilities, 120 hours of doctoral courses and workshops, networking events, and support from the UGA International Student Office. Visa fees and registration to the UGA Doctoral School are covered, and the program is open to all nationalities. Eligibility criteria require a Master's degree or equivalent by the application deadline, strong background in relevant fields (continuum mechanics, multiphysics, geomechanics, biophysics, biomechanics), skills in numerical methods (FEM, MPM, DEM), analytical developments, and 3D imaging. Excellent English proficiency is mandatory. Applicants must not have resided in France for more than 12 months in the past three years and must not already hold a doctoral degree. The application deadline is 28 February 2026, with the position starting on 1 October 2026. For more information and to apply, visit the PhD@Tec21 website.