Abstract
In shotcrete lining design there are a number of analysis methods available to estimate the ultimate point load resistance. However, little experimental evidence is available to confirm the validity of these estimates. To address this deficit, a series of full-scale load tests were undertaken on macro-synthetic fibre reinforced shotcrete (MSFRS) linings constructed in an underground coal mine in Queensland, and steel fibre reinforced shotcrete (SFRS) linings constructed as part of a tunnel project under construction in Sydney, Australia. Areas of lining were tested to destruction to identify the point load resistance. All the tests reported in this paper involved predominantly flexural failure of the shotcrete lining.The tests comprised regions of ∼70–100 mm thick FRS lining with bolts placed orthogonally at ∼1000–2500 mm centres. Load was applied using an inflatable lifting bag with a load capacity of about 500kN and maximum displacement capacity of 150 mm. Although the FRS used in the trials displayed post-crack strain-softening behaviour in accompanying ASTM C1550 tests, all the in situ tests resulted in strain-hardening behaviour with no evidence of a dip in load resistance upon cracking of the concrete matrix. The peak load resistance was many times greater than the load resistance measured at first crack, which was confirmed with numerical and analytical modelling. Substantial post-peak ductility was noted in all the tests.
Published Version
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