Abstract：The mechanism of the truss supporting loose roof is studied through physical simulation tests. Two arches named the first arch and the second arch are found in loose roof in simulation tests. The simplified mechanics model of the truss supporting loose roof is set up according to test results and in virtue of some theory. The two arches of truss supporting loose roof are studied thoroughly in theory. The deduced calculation formula provides calculation methods and theoretical references for parameters designs of truss supporting loose roof and is of important maturational meaning to practice.
