**1. Introduction**

Hydraulic fracturing (HF) has been widely used in the oil & gas (O&G) and mining industry: in O&G to stimulate reservoirs [1] and in mining, primarily to initiate caving and to improve fragmentation (e.g. [2-4]). Attempts have also been made to initiate slip on faults or shears [5] and research including mine-backs of hydraulically fractured zones has been conducted [6,7] in order to better understand the characteristics of the propagated hydraulic fractures. However, to the authors' knowledge, although there are many anecdotal indications of hydraulically induced changes to rock mass properties and stress, hydraulic fracturing has so far not been successful in inducing sufficient changes in the in situ or mining-induced stress field to be of practical value for risk mitigation related to violent seismic energy release in deep and high stress mining. It is speculated that the latter can only be achieved by the stimulation, mobilisation and enhancement of a natural fracture network rather than by solely generating a new system of induced hydraulic fractures. Hence, an innovative testing program, focussed on natural fracture network stimulation and the development of these techniques for stress management purposes is pursued. The mobilisation and development of a fracture network is also relevant for the optimal exploitation of tight gas or oil shale reservoirs, which closely resemble hard-rock situations (low permeability block, naturally fractured, stiff, low to moderate Poisson's ratio, etc.). The success of the proposed hydraulic injection program will be investigated during a mine-back test, and the results applied to mining and O&G applications.

In this paper, the results of the experimental design phase, outlining objectives and justifica‐ tions for planned experimental layouts, are presented. Preliminary plans for the first minethrough trial at Newcrest Mining's Cadia East mine in New South Wales, Australia are described.
