Study On Mechanical Performances Of Concrete-filled Steel Tube Support

The deformation control of roadway in soft rock is a difficult task in the world in mining engineering, and the deformation is large and long time is needed until stability. Therefore,the yielding ribs have been extensively adopted in soft surrounding rock. However, the yieldable steel ribs cannot provide sufficient ultimate strength with the application in practical engineering. Further, the yielding mechanism for ribs is also unstable, which depends on the friction between different units. Therefore, in this study, a concrete filled steel tubular structure with yielding connects is suggested as a high strength-yielding support system.The mechanical performance of the arc shape support system of the concrete filled steel tubular is investigated in this paper by experiments validation and numerical simulation.Following conclusions can be drawn:(1) The load-displacement responses of this suggested support system is investigated. A numerical model is firstly developed based on the plastic-damaged mode for concrete and the bilinearity model for steel tube. Then the numerical model is verified by the lab tests that the numerical results agree well with the test ones. A parametric study, including arc diameter,tube thickness, concrete strength, is discussed in details. The results indicate that the strength of the support system increases by increasing tube thickness and concrete strength. However,the strength decreases as increasing the arc diameter.(2) Investigation of the yielding performances of the porous steel connect is conducted.The influences of pore ratio, pore shape, pore array pitch and connect dimensions on the yielding behaviors are found. The results indicate the yielding strength increases by increasing the pore array pitch and connect dimensions while decreases as the pore ratio.(3) The mechanical performances of the concrete filled steel tubular system with yielding connects is further studied. The parametric studies of pore ratio, pore array pitch, concrete strength, tube thickness and friction coefficient on the load-displacement curves is discussed in details. The higher values of tube thickness, concrete strength, pore array pitch and friction coefficient can enhance the support strength while support strength can decrease as in creasing the pore ratio.