Failure analysis of rock with filled and unfilled flaws under excavation stress path

Abstract

Rock masses with filled flaws play the main bearing role after excavation of pre-grouting roadway. In this study, the excavation stress path was obtained by numerical simulation, and rocks with filled flaws were loaded under the conventional compression and excavation stress path respectively. The failure process was simultaneously monitored by digital image correlation method and acoustic emission equipment. The results showed that the three simultaneous changes were caused by the excavation stress path: 1) compaction; 2) non-uniform change in strength near the flaws; 3) pre-cracking occurs at the flaw tip. Compaction decreased the crack initiation angle of resin-filled specimens. Variations in strength near the flaw resulted in the alternate appearance of tensile and compressive deformation in unfilled specimens near the long side of the flaw. The deformation in cement-filled specimens changed from sudden to progressive, whereas that in resin-filled specimens was the opposite. Pre-cracking weakened the unfilled specimens and changed the propagation direction of shear cracks in cement-filled specimens.

Keywords

excavation stress path / filled flaws / grouting / crack propagation

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