Experimental Investigation on the Dynamic Mechanical Properties of the Combination of Surrounding Rock and Primary Support
In tunnel construction engineering,the surrounding rock and primary support are usually exposed to the complex loadings,such as explosion impact and excavation disturbance.The structural stability is an important reference for engineering designing.The sandstone and mortar are used to prepare the equal proportion specimens of primary support and surrounding rock in this paper.The dynamic tests are carried out by using variable diameter Hopkinson experimental system.The dynamic properties and failure characteristics of the combination structure under impact loads are studied.The influence of the radial thickness of the primary support and surrounding rock on the failure mode of the combination are analyzed.Results show that the thickness of mortar has a significant effect on the stress-strain and failure characteristics of the combination.The stress-time curves show bimodal characteristics because of the existence the mortar,and while the thickness of mortar and sandstone is consistent,the second peak of the stress increases significantly.The cracks firstly occurr in the interface between sandstone and mortar,and then spread around the specimen causing macroscopic tensile failure further.The research shows an importantly referential significance for the designing and the optimizing of tunnel engineering.
the surrounding structure of tunnelimpact loaddynamic mechanica testdynamic strengthfailure mode
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