One of the most common ways to measure deformation and strength characteristics of rocks in-situ is the pressuremeter test. This method involves loading of the wellbore wall with the stress through the impermeable membrane. Lame's elastic solution for thick-walled cylinder subjected to high internal pressure is used to estimate Young's modulus of the rock mass at a certain Poisson's ratio, which is taken from the reference book, measured on the core material in the laboratory or calculated from the elastic wave velocities. The disadvantages of this approach include a significant difference in the estimates of the elasticity modulus depending on the chosen method of research that results in incorrect calculations of the rock massif deformation characteristics. This work is aimed at improving the reliability of the borehole measurements of elastic modulus in the rocks through the pressuremeter and hydraulic fracturing data sharing. The idea of the developed method is to use two different and independent data sets: the first one is obtained from standard deformation studies in well while the second one describes the behaviour of the same well with fracture formed in the direction of the maximum compressive stress. The difference in the geometrical arrangement of loading systems leads to different dependencies between the involved characteristics; joint processing of the results will give the values of Young's modulus and Poisson's ratio of the enclosing rocks. To implement this method a new type of downhole equipment is developed. II consists of an automatic delivery system that allows carrying out measurements in long inseam boreholes at a considerable distance from the underground workings without usage of drill rods.


The widely used method of studying the deformation properties of rocks and soils in situ is pressuremeter test (Clarke, 1996; Amadei et al., 1995). The results are used in calculations of the stability and designing of underground constructions, predicting of geodynamic events.

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