## About Professor Itai Einav

**Rather than looking directly at practice, and only then at fundamentals, I work the other way around, inevitably targeting a wider range of applications by thinking out of the box.**

Professor Einav's research focuses on the fundamentals of granular, cellular and random materials, and addresses wide range of applications in geoscience, mining and mineral processing, pharmaceutics, materials, etc.

Material characterisation: I created a suite of thermo- and micro- mechanical tools to address fundamental questions in soil mechanics. I used these tools to make three fundamental advances. First, I demonstrated that in strain space, the yield surfaces of granular materials are non-convex, and that this is due to the nonlinear relations which describe intergranular contact mechanics. Second, I provided a robust micromechanical interpretation of the field variables in general random media, including soil, bone and paper, which explained the origin of kinematic hardening. Third, I established a ‘breakage mechanics’ theory for modelling confined comminution; this provided the first continuum approach to allow the prediction of evolving grain-size distribution in brittle granular materials. I recently announced a further advance, ‘breakage soil mechanics’. This was a specific application of the theory that explained three aspects of granular soil behaviour from a physical basis: the dependence on the initial granular grading and void ratio of (i) yielding and (ii) critical state; and the connection between isotropic hardening and particle fracture. Applied geomechanics: I solved a significant offshore problem by establishing energy-based variational principles for piles in elastoplastic soil, which overcame the disadvantages of using FEM calculations for investigating the behaviour of piles under general loading conditions. Of particular significance were our principles for analysing changes from ‘east–west’ to ‘north–south’ loading, since such continual changes over a long period may lead to earlier failure than conventionally understood. I developed a novel approach for solving penetration problems, combining the upper-bound and strain-path methods. I showed that the bearing capacity of full-flow penetrometers, such as T-bar and ball, must be interpreted in relation to strain rates and degradation effects, and that conventionally used bearing capacity factors can be wrong by as much as half to three times.

### Selected publications

**Itai****Einav**, Julio Valdes. 2008. On comminution and yield in brittle granular mixtures.*J. Mech. Phys. Solids.*In press (doi:10.1016/j.jmps.2008.02.002). Extended the breakage theory to predict (i) yield of granular mixtures based on the mineral contents and (ii) the grain size reduction of the individual mineral particles.**Itai Einav**. 2007. Breakage mechanics. Part I: Theory.*J. Mech. Phys. Solids.***55**(6), 1274-1297. (Part II: Modelling granular materials.*J. Mech. Phys. Solids.***55**(6), 1298-1320.)**Itai Einav**. 2007. Fracture propagation in brittle granular matter.*Proc. Roy. Soc. A.*463, 2087, pp., 3021-3035. Used breakage mechanics to establish the concept of critical comminution pressure for granular materials, complementing the work by AA Griffith for near-continuous solids.**Itai****Einav**. 2007. Soil mechanics: breaking ground.*Phil Trans Roy. Soc. A*, 365, 1861, pp., 2985-3002. Triennial Series, Christmas Issue (invited). A simple model of soil mechanics that explained three intrinsic aspects of soil behaviour that arise from the evolving fabric of particles.**Itai****Einav**, John P. Carter. 2007. On convexity, normality, pre-consolidation pressure and singularities of geomaterials.*Granular Matter.*Vol. 9, No. 1-2, pp., 87-96. The yield surfaces of granular materials in strain space are non-convex, given the nonlinear law that govern the interaction between particles.**Itai****Einav**, Ian F. Collins. 2007. A thermo-mechanical framework of plasticity based on probabilistic micro-mechanics.*J. Mech. Mater. Struct,*(invited paper, in press, accepted 15-5-2007)*.*A novel framework of characterisation for random materials based on the statistics of distributed strengths in a representative volume element.**Itai****Einav**, Mark F. Randolph. 2006. Effect of strain rate on mobilised strength and thickness of curved shear bands.*Géotechnique*Vol. 56, No. 7, pp., 501-504. A closed-form solution for normally consolidated clays.**Itai****Einav**, Mark F.*Int. J. Num. Meth. Engng.*Vol. 63(14). pp., 1991-2016 (Invited paper, 6 Nov 2003). A new approach to analyse the steady-state flow of soil surrounding a penetrating object in relation to cumulative degradation and strain-rate hardening.- Ian F. Collins,
**Itai****Einav**. 2005. On the validity of elastic/plastic decompositions in soil mechanics.*Proceeding of Symposium on**Elastoplasticity*. Kyushu University, Japan, T. Tanaka and T. Okayasu (eds), pp., 193-200. Proof of invalidity in the general granular case, given that nonlinear contact law governs the interaction between particles. **Itai****Einav**. 2005. Energy and variational principles for piles in dissipative soil.*Géotechnique*. Vol. 55(7), pp., 515-525. A new methodology to study the behaviour of piles in elastoplastic soils.