Overcome numerical modelling limitations

A packaged constitutive model to overcome the limitations of standard continuum approaches

Key features and benefits of the IUCM

50x

Faster modelling times

Construction time is generally reduced from 20 – 100 hours to 0.5 – 2 hours.

200

Validated cases worldwide

The method has been extensively validated using several well-documented and well-known mining case histories.

Less expertise needed

StopeX is made for everyday geotechnical engineering, working seamlessly with your existing data and familiar software

A unified material model that gathers the most notable recent advances in rock mechanics

IUCM was developed with the intention to address the limitations of the current material models used for rock mechanics. The role of a material model is to implicitly represent the underlying failure mechanisms that are in place without explicitly including the micro-structures, block interactions, or the fracturing process.

Therefore, a suitable material model is one that can correctly represent the primary controlling mechanisms that occur during the process of rock mass loading and failure.

Actual

Model

Peak Criterion

The IUCM employs the Hoek-Brown criterion to determine the instantaneous Mohr-Coulomb parameters, cohesion and friction,at each level of confining stress. The IUCM follows a simple computation procedure that uses the initialised pre-mining or induced stresses in a numerical model to obtain the instantaneous Mohr-Coulomb parameters. In the IUCM, the instantaneous peak Mohr-Coulomb parameters are updated in real-time as the model cycles and as new phases of confinement are formed owing to damage in nearby ones or new excavations.

Post Peak Criterion

Once the peak strength of a rock mass is reached, it fails andenters its post-peak state. If the loading condition continues, therock mass will eventually reach its ultimate or residual strength. The importance of apost-peak failure criterion becomes more pronounced when thestress over strength ratio of a rock mass increases.

The linear nature of the residual envelope in the IUCM, replicates cohesionand friction-softening at low confinement andcohesion-softening and friction-hardening under high confinement. This allows progressivefailure to occur near the boundary of the excavation while limiting the propagation of yield or plasticity zonesaway from the excavation boundaries, as observed in severalcase histories.

Elastic Softening

When rock undergoes failure and continuous loading, voids are generated within the rock mass. The greater the porosity of the rock mass, the lower its elastic modulus. The drop in rock mass modulus can significantly affect the redistribution of stresses around a failed area and the subsequent phases of induced confinement.

The impact of modulus-softening can be more pronounced in situations where significant rock mass yield or deformation is expected, for example in high-stress conditions, caving, or deep open pit mining.

Post-failure dilatancy

Dilatancy has a significant impact on the evolution and progression of damage in the post-failure state of a rock mass. In the IUCM, for simplicity and to reduce the number of required inputs, the decay of dilation with increasing plastic deformation is replicated through a fundamental understanding that the dilation angle is at its peak when the volumetric strain is negligible and tends to zero, once the maximum possible volumetric strain is reached in the model.

Strength Anisotropy

Strength anisotropy is perhaps one of the most important but commonly neglected mechanical properties that exists in some rock types. In the IUCM, the strength anisotropy feature is only applicable for rock types that have the ‘intact rock anisotropy’ characteristic and therefore exhibit directional dependency at both small and large scales.

In the IUCM Anisotropy is included through the application of a Hoek-Brown failure envelope for the anisotropy plane as well as the main rock matrix.