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Abstract

The basic type of rock mass reinforcement method for both preparatory and operational workings in underground metal ore mines, both in Poland and in different countries across the world, is the expansion shell or adhesive-bonded rock bolt. The article discusses results of static loading test of the expansion shell rock bolts equipped with originally developed deformable component. This component consists of two profiled rock bolt washers, two disk springs, and three guide bars. The disk spring and disk washer material differs in stiffness. The construction materials ensure that at first the springs under loading are partially compressed, and then the rock bolt washer is plastically deformed. The rock bolts tested were installed in blocks simulating a rock mass with rock compressive strength of 80 MPa. The rock bolt was loaded statically until its ultimate loading capacity was exceeded. The study presents the results obtained under laboratory conditions in the test rig allowing testing of the rock bolts at their natural size, as used in underground metal ore mines. The stress-strain/displacement characteristics of the expansion shell rock bolt with the deformable component were determined experimentally. The relationships between the geometric parameters and specific strains or displacements of the bolt rod were described, and the percentage contribution of those values in total displacements, resulting from the deformation of rock bolt support components (washer, thread) and the expansion shell head displacements, were estimated. The stiffness of the yielded and stiff bolts was empirically determined, including stiffness parameters of every individual part (deformable component, steel rod). There were two phases of displacement observed during the static tension of the rock bolt which differed in their intensity.

Construction and Building Materials 95 788 – 801 https://doi.org/10.1016/J.CONBUILDMAT.2015.07.055 Brown, W. F., & Srawley, J. E. (1966). Plane Strain Crack Toughness Testing of High Strength Metallic Materials Philadelphia: ASTM International. https://doi.org/10.1520/STP410-EB Brown W. F. & Srawley J. E. 1966 Plane Strain Crack Toughness Testing of High Strength Metallic Materials Philadelphia ASTM International https://doi.org/10.1520/STP410-EB Contrafatto, L., & Cosenza, R. (2014). Behaviour of post-installed adhesive anchors in natural stone. Construction and

specifically, this study is concerned with the numerical simulation of the behavior of a lunar regolith backfill retained by concrete walls, which ideally could allow a better soil deposition and compaction, in order to make either a cover for a lunar base or a road for rovers. The reason for a regolith layer covering the lunar base is the environment in which it would be built [ 7 ] : continuous solar and cosmic radiation, extremes in temperature and radiation, meteorites [ 8 ] , abrasive and adhesive dust. It appears that at least 2.5 m of regolith cover would be