Russian State Geological Prospecting University of S. Ordzhonikidze, Moscow, Russia:

O. S. Bryukhovetskiy, Head of Center of Scientific, Technical and Environmental Evaluation of Mining and Geological Operations, Professor, Doctor of Engineering Sciences, bos.rggru@mail.ru
Yu. A. Borovkov, Professor, Doctor of Engineering Sciences
I. Yu. Naydenko, Associate Professor, Candidate of Engineering Sciences

One of the jet technologies is hydraulic borehole mining successfully applied at the stage of lifting big process mineral samples. A common geomechanical factor for erodible minerals is their structural strength value that should be not higher than 7 MPa for the existing models of borehole jets. This article proposes the method to determine basic geomechanical parameters of thin holes made by borehole jets. Washing-out is carried out by free jets in dried excavation zone with hydraulic elevation of slurry. This creates favorable conditions for the next fill of the holes with an anti-seepage material. The geomechanical calculation is based on a rheological model. Thin holes are used in construction of seepage or anti-seepage walls, in recovery or enhancement of well production, and in soil reinforcement. The authors analyze interaction between parameters of a thin hole such as length, width and tolerance time. Aimed at the local improvement of ecological situation at Orsknefteorgsintez refiner, anti-seepage curtains 110 m long, 15–20 m high and 5–230 m deep have been created. As a consequence, fluid loss gradient has decreased more than by an order of magnitude. Based on the performed analysis, the following conclusions have been drawn: 01–0.3 wide holes have no influence on next deformation behavior and temporal stability; within the current limit of time taken by drivage, assembling-disassembling and backfilling, stability of walls in a hole, including close-spaced holes inside a depth interval studied, is guaranteed; it is possible to implement hydraulicking in two boreholes with close-spaced thin holes not wider than 0.2 m.

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