This article addresses the issue of tunnel collapses caused by the cracking of steel fiber-reinforced shotcrete (SRA), which compromises the stability of linings by exposing the fibers to corrosive agents, leading to oxidation and loss of load-bearing capacity. As a solution, it proposes optimizing the mixtures by combining steel fibers with polypropylene micro-synthetic fibers (SRH), evaluating their performance compared to SRA in terms of cracking and compressive strength. To simulate real conditions, the properties of fresh concrete were adjusted in the laboratory, and the mixtures were sprayed onto panels following EFNARC guidelines. Compressive strength was assessed by extracting cores from sprayed blocks and testing molded specimens. The results show that SRH mixtures do not exhibit visible cracks, unlike SRA, which shows cracking. Regarding strength, both designs exceeded 40 MPa at 21 days in molded specimens, while cores reached 33 MPa at 14 days, complying with the Chilean Shotcrete Guide and EFNARC. The study concludes that SRA offers better initial performance up to 7 days but presents visible cracking. In contrast, SRH mixtures achieve adequate early-age strength and higher long-term resistance without cracking, validating their effectiveness as a viable alternative to mitigate tunnel collapses.