About Compression Fracture

The paper discusses fracture processes occurring under compressive loads. The processes are considered from two points of view: (i) compression fracture mechanisms and their effect on the strength and fracture resistance of the material, and (ii) the effect of geometric constraints on the stress-strain state and fracture conditions of bodies (natural objects) with cracks and crack-like defects. These are particularly the effects associated with crack surface contact, friction, and loading history. Fracture structures are described which form in the conditions of high-rate compression under extreme loads typical of tectonic processes and deep hydrocarbon production. The structures include crack-like compaction regions in highly porous brittle materials (rocks) formed under compression, which present a new form of quasi-brittle mode I fracture (a compression crack). A method is proposed for estimating the effective strength of compressed bodies with one dimension (thickness) being much smaller than the other two and that have through-thickness variable properties and/or composition. As an example, the ice cover strength with respect to longitudinal compression is considered taking into account a partial loss of the ice bearing capacity. The influence of geometric constraints on the fracture mechanisms in fractured thin bodies is discussed. It is shown that the compression fracture of bodies with elongated through holes (or crack-like defects), whose length is much larger than the body thickness, occurs by a mechanism induced by the overlapping of crack surfaces.