Gray, I 2017, 'Effective stress in rock', in J Wesseloo (ed.), Deep Mining 2017: Proceedings of the Eighth International Conference on Deep and High Stress Mining, Australian Centre for Geomechanics, Perth, pp. 199-207, https://doi.org/10.36487/ACG_rep/1704_12_Gray (https://papers.acg.uwa.edu.au/p/1704_12_Gray/) Abstract: This paper looks at what is the meaning of effective stress in rock and how it is measured. The paper examines the field measurement of stress in intact and jointed systems including fluid pressure and how it acts within the matrix and joints. How the fluid pressure acts varies between rock types and structure. The processes of stress measurement by overcoring and hydrofracture are considered and the benefits and deficiencies of each system discussed. The determination of Biot’s poroelastic coefficient and how this relates to a fractured system are discussed. The importance of effective stress on failures within rock are considered. Keywords: stress, fluid, pressure, rock, effective, poroelastic, joints, Biot