An Innovative Tubular Standing Support Incorporating PVC and FRP Composites: Laboratory Tests

The importance of developing innovative support structure for underground mines has drawn much attention with the depletion of shallow resources. This paper presents a hybrid tubular standing support consisting of an exterior container made of the polyvinyl chloride (PVC) and fibre-reinforced polymer (FRP) while the infill is the coal rejects based backfill material. The FRP jacket featured with the high strength-to-weight ratio is attached on the exterior surface of the PVC tube with the large rupture strain to provide confinement to infilled backfill material. A series of laboratory tests were conducted on this FRP-PVC tubular standing support (FPTSS) with different FRP thickness. Meanwhile, the FRP tubular standing support and the PVC tubular standing support with the sole confining material were also prepared and tested. Tests results showed that the FPTSS specimen exhibited the typical strain hardening behaviour attributed to the effective confinement provided by the combined container. It is also indicated that the enhancement of either the compressive strength or the axial deformation ability is closely related to FRP thickness. The other comparative advantage of FPTSS obtained from this research is its ductile post-peak behaviour after the rupture of the exterior FRP jacket, indicating the importance of using PVC tube in FPTSS. Except for its superior compressive behaviour, the cost effectiveness and ease of construction of FPTSS are also attractive from the design aspect.